title: Rectifier

text: With the advent of diodes and thyristors, these circuits have become less popular and the three-phase bridge circuit has become the most common circuit.


title: Rectifier

text: For an uncontrolled three-phase bridge rectifier, six diodes are used, and the circuit again has a pulse number of six. For this reason, it is also commonly referred to as a six-pulse bridge. The B6 circuit can be seen simplified as a series connection of two three-pulse center circuits.


title: Rectifier

text: For low-power applications, double diodes in series, with the anode of the first diode connected to the cathode of the second, are manufactured as a single component for this purpose. Some commercially available double diodes have all four terminals available so the user can configure them for single-phase split supply use, half a bridge, or three-phase rectifier.


title: Rectifier

text: For higher-power applications, a single discrete device is usually used for each of the six arms of the bridge. For the very highest powers, each arm of the bridge may consist of tens or hundreds of separate devices in parallel (where very high current is needed, for example in aluminium smelting) or in series (where very high voltages are needed, for example in high-voltage direct current power transmission).


title: Rectifier

text: The pulsating DC voltage results from the differences of the instantaneous positive and negative phase voltages formula_3, phase-shifted by 30°:


title: Rectifier

text: The ideal, no-load average output voltage formula_11 of the B6 circuit results from the integral under the graph of a DC voltage pulse with the period duration of formula_12 (from 60° to 120°) with the peak value formula_13:


title: Rectifier

text: If the three-phase bridge rectifier is operated symmetrically (as positive and negative supply voltage), the center point of the rectifier on the output side (or the so-called isolated reference potential) opposite the center point of the transformer (or the neutral conductor) has a potential difference in the form of a triangular common-mode voltage. For this reason, these two centers must never be connected to each other, otherwise short-circuit currents would flow. The ground of the three-phase bridge rectifier in symmetrical operation is thus decoupled from the neutral conductor or the earth of the mains voltage. Powered by a transformer, earthing of the center point of the bridge is possible, provided that the secondary winding of the transformer is electrically isolated from the mains voltage and the star point of the secondary winding is not on earth. In this case, however, (negligible) leakage currents are flowing over the transformer windings.


title: Rectifier

text: The common-mode voltage is formed out of the respective average values of the differences between the positive and negative phase voltages, which form the pulsating DC voltage. The peak value of the delta voltage formula_17 amounts ¼ of the peak value of the phase input voltage formula_2 and is calculated with formula_2 minus half of the DC voltage at 60° of the period:


title: Rectifier

text: The RMS value of the common-mode voltage is calculated from the form factor for triangular oscillations:


title: Rectifier

text: If the circuit is operated asymmetrically (as a simple supply voltage with just one positive pole), both the positive and negative poles (or the isolated reference potential) are pulsating opposite the center (or the ground) of the input voltage analogously to the positive and negative waveforms of the phase voltages. However, the differences in the phase voltages result in the six-pulse DC voltage (over the duration of a period). The strict separation of the transformer center from the negative pole (otherwise short-circuit currents will flow) or a possible grounding of the negative pole when powered by an isolating transformer apply correspondingly to the symmetrical operation.


title: Rectifier

text: The controlled three-phase bridge rectifier uses thyristors in place of diodes. The output voltage is reduced by the factor cos(α):


title: Rectifier

text: The above equations are only valid when no current is drawn from the AC supply or in the theoretical case when the AC supply connections have no inductance. In practice, the supply inductance causes a reduction of DC output voltage with increasing load, typically in the range 10–20% at full load.


title: Rectifier

text: The effect of supply inductance is to slow down the transfer process (called commutation) from one phase to the next. As result of this is that at each transition between a pair of devices, there is a period of overlap during which three (rather than two) devices in the bridge are conducting simultaneously. The overlap angle is usually referred to by the symbol μ (or u), and may be 20 30° at full load.


title: Rectifier

text: The overlap angle μ is directly related to the DC current, and the above equation may be re-expressed as:


title: Rectifier

text: Although better than single-phase rectifiers or three-phase half-wave rectifiers, six-pulse rectifier circuits still produce considerable harmonic distortion on both the AC and DC connections. For very high-power rectifiers the twelve-pulse bridge connection is usually used. A twelve-pulse bridge consists of two six-pulse bridge circuits connected in series, with their AC connections fed from a supply transformer that produces a 30° phase shift between the two bridges. This cancels many of the characteristic harmonics the six-pulse bridges produce.


title: Rectifier

text: The 30-degree phase shift is usually achieved by using a transformer with two sets of secondary windings, one in star (wye) connection and one in delta connection.


title: Rectifier

text: The simple half-wave rectifier can be built in two electrical configurations with the diodes pointing in opposite directions, one version connects the negative terminal of the output direct to the AC supply and the other connects the positive terminal of the output direct to the AC supply. By combining both of these with separate output smoothing it is possible to get an output voltage of nearly double the peak AC input voltage. This also provides a tap in the middle, which allows use of such a circuit as a split rail power supply.


title: Rectifier

text: A variant of this is to use two capacitors in series for the output smoothing on a bridge rectifier then place a switch between the midpoint of those capacitors and one of the AC input terminals. With the switch open, this circuit acts like a normal bridge rectifier. With the switch closed, it acts like a voltage doubling rectifier. In other words, this makes it easy to derive a voltage of roughly 320 V (±15%, approx.) DC from any 120 V or 230 V mains supply in the world, this can then be fed into a relatively simple switched-mode power supply. However, for a given desired ripple, the value of both capacitors must be twice the value of the single one required for a normal bridge rectifier; when the switch is closed each one must filter the output of a half-wave rectifier, and when the switch is open the two capacitors are connected in series with an equivalent value of half one of them.


title: Rectifier

text: Cascaded diode and capacitor stages can be added to make a voltage multiplier (Cockroft-Walton circuit). These circuits are capable of producing a DC output voltage potential up to about ten times the peak AC input voltage, in practice limited by current capacity and voltage regulation issues. Diode voltage multipliers, frequently used as a trailing boost stage or primary high voltage (HV) source, are used in HV laser power supplies, powering devices such as cathode ray tubes (CRT) (like those used in CRT based television, radar and sonar displays), photon amplifying devices found in image intensifying and photo multiplier tubes (PMT), and magnetron based radio frequency (RF) devices used in radar transmitters and microwave ovens. Before the introduction of semiconductor electronics, transformerless vacuum tube receivers powered directly from AC power sometimes used voltage doublers to generate roughly 300 VDC from a 100–120 V power line.


title: Rectifier

text: Several ratios are used to quantify the function and performance of rectifiers or their output, including transformer utilization factor (TUF), conversion ratio ("η"), ripple factor, form factor, and peak factor. The two primary measures are DC voltage (or offset) and peak-peak ripple voltage, which are constituent components of the output voltage.


title: Rectifier

text: Conversion ratio (also called "rectification ratio", and confusingly, "efficiency") "η" is defined as the ratio of DC output power to the input power from the AC supply. Even with ideal rectifiers, the ratio is less than 100% because some of the output power is AC power rather than DC which manifests as ripple superimposed on the DC waveform. The ratio can be improved with the use of smoothing circuits which reduce the ripple and hence reduce the AC content of the output. Conversion ratio is reduced by losses in transformer windings and power dissipation in the rectifier element itself. This ratio is of little practical significance because a rectifier is almost always followed by a filter to increase DC voltage and reduce ripple. In some three-phase and multi-phase applications the conversion ratio is high enough that smoothing circuitry is unnecessary.


title: Rectifier

text: In other circuits, like filament heater circuits in vacuum tube electronics where the load is almost entirely resistive, smoothing circuitry may be omitted because resistors dissipate both AC and DC power, so no power is lost.


title: Rectifier

text: Three-phase rectifiers, especially three-phase full-wave rectifiers, have much greater conversion ratios because the ripple is intrinsically smaller.


title: Rectifier

text: The transformer utilization factor (TUF) of a rectifier circuit is defined as the ratio of the DC power available at the input resistor to the AC rating of the output coil of a transformer.


title: Rectifier

text: A real rectifier characteristically drops part of the input voltage (a voltage drop, for silicon devices, of typically 0.7 volts plus an equivalent resistance, in general non-linear)—and at high frequencies, distorts waveforms in other ways. Unlike an ideal rectifier, it dissipates some power.


title: Rectifier

text: An aspect of most rectification is a loss from the peak input voltage to the peak output voltage, caused by the built-in voltage drop across the diodes (around 0.7 V for ordinary silicon p–n junction diodes and 0.3 V for Schottky diodes). Half-wave rectification and full-wave rectification using a center-tapped secondary produces a peak voltage loss of one diode drop. Bridge rectification has a loss of two diode drops. This reduces output voltage, and limits the available output voltage if a very low alternating voltage must be rectified. As the diodes do not conduct below this voltage, the circuit only passes current through for a portion of each half-cycle, causing short segments of zero voltage (where instantaneous input voltage is below one or two diode drops) to appear between each "hump".


title: Rectifier

text: Peak loss is very important for low voltage rectifiers (for example, 12 V or less) but is insignificant in high-voltage applications such as HVDC power transmission systems.


title: Rectifier

text: Non-linear loads like rectifiers produce current harmonics of the source frequency on the AC side and voltage harmonics of the source frequency on the DC side, due to switching behavior.


title: Rectifier

text: While half-wave and full-wave rectification deliver unidirectional current, neither produces a constant voltage. There is a large AC ripple voltage component at the source frequency for a half-wave rectifier, and twice the source frequency for a full-wave rectifier. Ripple voltage is usually specified peak-to-peak. Producing steady DC from a rectified AC supply requires a smoothing circuit or filter. In its simplest form this can be just a capacitor (functioning as both a smoothing capacitor as well as a reservoir, buffer or bulk capacitor), choke, resistor, Zener diode and resistor, or voltage regulator placed at the output of the rectifier. In practice, most smoothing filters utilize multiple components to efficiently reduce ripple voltage to a level tolerable by the circuit.


title: Rectifier

text: The filter capacitor releases its stored energy during the part of the AC cycle when the AC source does not supply any power, that is, when the AC source changes its direction of flow of current.


title: Rectifier

text: The above diagram shows reservoir performance from a near zero impedance source, such as a mains supply. As the rectifier voltage increases, it charges the capacitor and also supplies current to the load. At the end of the quarter cycle, the capacitor is charged to its peak value Vp of the rectifier voltage. Following this, the rectifier voltage starts to decrease to its minimum value Vmin as it enters the next quarter cycle. This initiates the discharge of the capacitor through the load.


title: Rectifier

text: The size of the capacitor C is determined by the amount of ripple r that can be tolerated, where r=(Vp-Vmin)/Vp.


title: Rectifier

text: These circuits are very frequently fed from transformers, and have significant resistance. Transformer resistance modifies the reservoir capacitor waveform, changes the peak voltage, and introduces regulation issues.


title: Rectifier

text: For a given load, sizing of a smoothing capacitor is a tradeoff between reducing ripple voltage and increasing ripple current. The peak current is set by the rate of rise of the supply voltage on the rising edge of the incoming sine-wave, reduced by the resistance of the transformer windings. High ripple currents increase IR losses (in the form of heat) in the capacitor, rectifier and transformer windings, and may exceed the ampacity of the components or VA rating of the transformer. Vacuum tube rectifiers specify the maximum capacitance of the input capacitor, and SS diode rectifiers also have current limitations. Capacitors for this application need low ESR, or ripple current may overheat them. To limit ripple voltage to a specified value the required capacitor size is proportional to the load current and inversely proportional to the supply frequency and the number of output peaks of the rectifier per input cycle. Full-wave rectified output requires a smaller capacitor because it is double the frequency of half-wave rectified output. To reduce ripple to a satisfactory limit with just a single capacitor would often require a capacitor of impractical size. This is because the ripple current rating of a capacitor does not increase linearly with size and there may also be height limitations. For high current applications banks of capacitors are used instead.


title: Rectifier

text: It is also possible to put the rectified waveform into a choke-input filter. The advantage of this circuit is that the current waveform is smoother: current is drawn over the entire cycle, instead of being drawn in pulses at the peaks of AC voltage each half-cycle as in a capacitor input filter. The disadvantage is that the voltage output is much lower – the average of an AC half-cycle rather than the peak; this is about 90% of the RMS voltage versus formula_40 times the RMS voltage (unloaded) for a capacitor input filter. Offsetting this is superior voltage regulation and higher available current, which reduce peak voltage and ripple current demands on power supply components. Inductors require cores of iron or other magnetic materials, and add weight and size. Their use in power supplies for electronic equipment has therefore dwindled in favour of semiconductor circuits such as voltage regulators.


title: Rectifier

text: In cases where ripple voltage is insignificant, like battery chargers, the input filter may be a single series resistor to adjust the output voltage to that required by the circuit. A resistor reduces both output voltage and ripple voltage proportionately. A disadvantage of a resistor input filter is that it consumes power in the form of waste heat that is not available to the load, so it is employed only in low current circuits.


title: Rectifier

text: To further reduce ripple, the initial filter element may be followed by additional alternating series and shunt filter components, or by a voltage regulator. Series filter components may be resistors or chokes; shunt elements may be resistors or capacitors. The filter may raise DC voltage as


title: Rectifier

text: well as reduce ripple. Filters are often constructed from pairs of series/shunt components called RC (series resistor, shunt capacitor) or LC (series choke, shunt capacitor) sections. Two common filter geometries are known as Pi (capacitor, choke, capacitor) and T (choke, capacitor, choke) filters.


title: Rectifier

text: Sometimes the series elements are resistors - because resistors are smaller and cheaper - when a lower DC output is desirable or permissible. Another


title: Rectifier

text: kind of special filter geometry is a series resonant choke or tuned choke filter. Unlike the other filter geometries which are low-pass filters, a resonant choke filter is a band-stop filter: it is a parallel combination of choke and capacitor which resonates at the frequency of the ripple voltage, presenting a very high impedance to the ripple. It may be followed by a shunt capacitor to complete the filter.


title: Rectifier

text: A more usual alternative to additional filter components, if the DC load requires very low ripple voltage, is to follow the input filter with a voltage regulator. A voltage regulator operates on a different principle than a filter, which is essentially a voltage divider that shunts voltage at the ripple frequency away from the load. Rather, a regulator increases or decreases current supplied to the load in order to maintain a constant output voltage.


title: Rectifier

text: A simple passive shunt voltage regulator may consist of a series resistor to drop source voltage to the required level and a Zener diode shunt with reverse


title: Rectifier

text: voltage equal to the set voltage. When input voltage rises, the diode dumps current to maintain the set output voltage. This kind of regulator is usually employed only in low voltage, low current circuits because Zener diodes have both voltage and current limitations. It is also very inefficient, because it dumps excess current, which is not available to the load.


title: Rectifier

text: A more efficient alternative to a shunt voltage regulator is an active voltage regulator circuit. An active regulator employs reactive components to store and discharge energy, so that most or all current supplied by the rectifier is passed to the load. It may also use negative and positive feedback in conjunction with at least one voltage amplifying component like a transistor to maintain output voltage when source voltage drops. The input filter must prevent the troughs of the ripple dropping below the minimum voltage required by the regulator to produce the required output voltage. The regulator serves both to significantly reduce the ripple and to deal with variations in supply and load characteristics.


title: Rectifier

text: The primary application of rectifiers is to derive DC power from an AC supply (AC to DC converter). Rectifiers are used inside the power supplies of virtually all electronic equipment. AC/DC power supplies may be broadly divided into linear power supplies and switched-mode power supplies. In such power supplies, the rectifier will be in series following the transformer, and be followed by a smoothing filter and possibly a voltage regulator.


title: Rectifier

text: Converting DC power from one voltage to another is much more complicated. One method of DC-to-DC conversion first converts power to AC (using a device called an inverter), then uses a transformer to change the voltage, and finally rectifies power back to DC. A frequency of typically several tens of kilohertz is used, as this requires much smaller inductance than at lower frequencies and obviates the use of heavy, bulky, and expensive iron-cored transformers. Another method of converting DC voltages uses a charge pump, using rapid switching to change the connections of capacitors; this technique is generally limited to supplies up to a couple of watts, owing to the size of capacitors required.


title: Rectifier

text: Rectifiers are also used for detection of amplitude modulated radio signals. The signal may be amplified before detection. If not, a very low voltage drop diode or a diode biased with a fixed voltage must be used. When using a rectifier for demodulation the capacitor and load resistance must be carefully matched: too low a capacitance makes the high frequency carrier pass to the output, and too high makes the capacitor just charge and stay charged.


title: Rectifier

text: Rectifiers supply polarized voltage for welding. In such circuits control of the output current is required; this is sometimes achieved by replacing some of the diodes in a bridge rectifier with thyristors, effectively diodes whose voltage output can be regulated by switching on and off with phase-fired controllers.


title: Rectifier

text: Thyristors are used in various classes of railway rolling stock systems so that fine control of the traction motors can be achieved. Gate turn-off thyristors are used to produce alternating current from a DC supply, for example on the Eurostar Trains to power the three-phase traction motors.


title: Rectifier

text: Before about 1905 when tube-type rectifiers were developed, power conversion devices were purely electro-mechanical in design. Mechanical rectifiers used some form of rotation or resonant vibration driven by electromagnets, which operated a switch or commutator to reverse the current.


title: Rectifier

text: These mechanical rectifiers were noisy and had high maintenance requirements, including lubrication and replacement of moving parts due to wear. Opening mechanical contacts under load resulted in electrical arcs and sparks that heated and eroded the contacts. They also were not able to handle AC frequencies above several thousand cycles per second.


title: Rectifier

text: To convert alternating into direct current in electric locomotives, a synchronous rectifier may be used. It consists of a synchronous motor driving a set of heavy-duty electrical contacts. The motor spins in time with the AC frequency and periodically reverses the connections to the load at an instant when the sinusoidal current goes through a zero-crossing. The contacts do not have to "switch" a large current, but they must be able to "carry" a large current to supply the locomotive's DC traction motors.


title: Rectifier

text: These consisted of a resonant reed, vibrated by an alternating magnetic field created by an AC electromagnet, with contacts that reversed the direction of the current on the negative half cycles. They were used in low power devices, such as battery chargers, to rectify the low voltage produced by a step-down transformer. Another use was in battery power supplies for portable vacuum tube radios, to provide the high DC voltage for the tubes. These operated as a mechanical version of modern solid state switching inverters, with a transformer to step the battery voltage up, and a set of vibrator contacts on the transformer core, operated by its magnetic field, to repeatedly break the DC battery current to create a pulsing AC to power the transformer. Then a second set of rectifier contacts on the vibrator rectified the high AC voltage from the transformer secondary to DC.


title: Rectifier

text: A "motor-generator set", or the similar "rotary converter", is not strictly a rectifier as it does not actually "rectify" current, but rather "generates" DC from an AC source. In an "M-G set", the shaft of an AC motor is mechanically-coupled to that of a DC generator. The DC generator produces multiphase alternating currents in its armature windings, which a commutator on the armature shaft converts into a direct current output; or a homopolar generator produces a direct current without the need for a commutator. M-G sets are useful for producing DC for railway traction motors, industrial motors and other high-current applications, and were common in many high-power DC uses (for example, carbon-arc lamp projectors for outdoor theaters) before high-power semiconductors became widely available.


title: Rectifier

text: The electrolytic rectifier was a device from the early twentieth century that is no longer used. A home-made version is illustrated in the 1913 book "The Boy Mechanic" but it would be suitable for use only at very low voltages because of the low breakdown voltage and the risk of electric shock. A more complex device of this kind was patented by G. W. Carpenter in 1928 (US Patent 1671970).


title: Rectifier

text: When two different metals are suspended in an electrolyte solution, direct current flowing one way through the solution sees less resistance than in the other direction. Electrolytic rectifiers most commonly used an aluminum anode and a lead or steel cathode, suspended in a solution of triammonium orthophosphate.


title: Rectifier

text: The rectification action is due to a thin coating of aluminium hydroxide on the aluminum electrode, formed by first applying a strong current to the cell to build up the coating. The rectification process is temperature-sensitive, and for best efficiency should not operate above 86 °F (30 °C). There is also a breakdown voltage where the coating is penetrated and the cell is short-circuited. Electrochemical methods are often more fragile than mechanical methods, and can be sensitive to usage variations, which can drastically change or completely disrupt the rectification processes.


title: Rectifier

text: Similar electrolytic devices were used as lightning arresters around the same era by suspending many aluminium cones in a tank of triammonium orthophosphate solution. Unlike the rectifier above, only aluminium electrodes were used, and used on A.C., there was no polarization and thus no rectifier action, but the chemistry was similar.


title: Rectifier

text: The modern electrolytic capacitor, an essential component of most rectifier circuit configurations was also developed from the electrolytic rectifier.


title: Rectifier

text: The development of vacuum tube technology in the early 20th century resulted in the invention of various tube-type rectifiers, which largely replaced the noisy, inefficient mechanical rectifiers.


title: Rectifier

text: A rectifier used in high-voltage direct current (HVDC) power transmission systems and industrial processing between about 1909 to 1975 is a "mercury-arc rectifier" or "mercury-arc valve". The device is enclosed in a bulbous glass vessel or large metal tub. One electrode, the cathode, is submerged in a pool of liquid mercury at the bottom of the vessel and one or more high purity graphite electrodes, called anodes, are suspended above the pool. There may be several auxiliary electrodes to aid in starting and maintaining the arc. When an electric arc is established between the cathode pool and suspended anodes, a stream of electrons flows from the cathode to the anodes through the ionized mercury, but not the other way (in principle, this is a higher-power counterpart to flame rectification, which uses the same one-way current transmission properties of the plasma naturally present in a flame).


title: Rectifier

text: These devices can be used at power levels of hundreds of kilowatts, and may be built to handle one to six phases of AC current. Mercury-arc rectifiers have been replaced by silicon semiconductor rectifiers and high-power thyristor circuits in the mid 1970s. The most powerful mercury-arc rectifiers ever built were installed in the Manitoba Hydro Nelson River Bipole HVDC project, with a combined rating of more than 1 GW and 450 kV.


title: Rectifier

text: The General Electric Tungar rectifier was a mercury vapor (ex.:5B24) or argon (ex.:328) gas-filled electron tube device with a tungsten filament cathode and a carbon button anode. It operated similarly to the thermionic vacuum tube diode, but the gas in the tube ionized during forward conduction, giving it a much lower forward voltage drop so it could rectify lower voltages. It was used for battery chargers and similar applications from the 1920s until lower-cost metal rectifiers, and later semiconductor diodes, supplanted it. These were made up to a few hundred volts and a few amperes rating, and in some sizes strongly resembled an incandescent lamp with an additional electrode.


title: Rectifier

text: The 0Z4 was a gas-filled rectifier tube commonly used in vacuum tube car radios in the 1940s and 1950s. It was a conventional full-wave rectifier tube with two anodes and one cathode, but was unique in that it had no filament (thus the "0" in its type number). The electrodes were shaped such that the reverse breakdown voltage was much higher than the forward breakdown voltage. Once the breakdown voltage was exceeded, the 0Z4 switched to a low-resistance state with a forward voltage drop of about 24 V.


title: Rectifier

text: The thermionic vacuum tube diode, originally called the Fleming valve, was invented by John Ambrose Fleming in 1904 as a detector for radio waves in radio receivers, and evolved into a general rectifier. It consisted of an evacuated glass bulb with a filament heated by a separate current, and a metal plate anode. The filament emitted electrons by thermionic emission (the Edison effect), discovered by Thomas Edison in 1884, and a positive voltage on the plate caused a current of electrons through the tube from filament to plate. Since only the filament produced electrons, the tube would only conduct current in one direction, allowing the tube to rectify an alternating current.


title: Rectifier

text: Thermionic diode rectifiers were widely used in power supplies in vacuum tube consumer electronic products, such as phonographs, radios, and televisions, for example the All American Five radio receiver, to provide the high DC plate voltage needed by other vacuum tubes. "Full-wave" versions with two separate plates were popular because they could be used with a center-tapped transformer to make a full-wave rectifier. Vacuum tube rectifiers were made for very high voltages, such as the high voltage power supply for the cathode ray tube of television receivers, and the kenotron used for power supply in X-ray equipment. However, compared to modern semiconductor diodes, vacuum tube rectifiers have high internal resistance due to space charge and therefore high voltage drops, causing high power dissipation and low efficiency. They are rarely able to handle currents exceeding 250 mA owing to the limits of plate power dissipation, and cannot be used for low voltage applications, such as battery chargers. Another limitation of the vacuum tube rectifier is that the heater power supply often requires special arrangements to insulate it from the high voltages of the rectifier circuit.


title: Rectifier

text: The crystal detector was the earliest type of semiconductor diode. Invented by Jagadish Chandra Bose and developed by G. W. Pickard starting in 1902, it was a significant improvement over earlier detectors such as the coherer. The crystal detector was widely used prior to vacuum tubes becoming available. One popular type of crystal detector, often called a "cat's whisker detector", consists of a crystal of some semiconducting mineral, usually galena (lead sulfide), with a light springy wire touching its surface. Its fragility and limited current capability made it unsuitable for power supply applications. In the 1930s, researchers miniaturized and improved the crystal detector for use at microwave frequencies.


title: Rectifier

text: Once common until replaced by more compact and less costly silicon solid-state rectifiers in the 1970s, these units used stacks of oxide-coated metal plates and took advantage of the semiconductor properties of selenium or copper oxide. While selenium rectifiers were lighter in weight and used less power than comparable vacuum tube rectifiers, they had the disadvantage of finite life expectancy, increasing resistance with age, and were only suitable to use at low frequencies. Both selenium and copper oxide rectifiers have somewhat better tolerance of momentary voltage transients than silicon rectifiers.


title: Rectifier

text: Typically these rectifiers were made up of stacks of metal plates or washers, held together by a central bolt, with the number of stacks determined by voltage; each cell was rated for about 20 V. An automotive battery charger rectifier might have only one cell: the high-voltage power supply for a vacuum tube might have dozens of stacked plates. Current density in an air-cooled selenium stack was about 600 mA per square inch of active area (about 90 mA per square centimeter).


title: Rectifier

text: Silicon diodes are the most widely used rectifiers for lower voltages and powers, and have largely replaced other rectifiers. Due to their substantially lower forward voltage (0.3V versus 0.7V for silicon diodes) germanium diodes have an inherent advantage over silicon diodes in low voltage circuits.


title: Rectifier

text: In high-power applications, from 1975 to 2000, most mercury valve arc-rectifiers were replaced by stacks of very high power thyristors, silicon devices with two extra layers of semiconductor, in comparison to a simple diode.


title: Rectifier

text: In medium-power transmission applications, even more complex and sophisticated voltage sourced converter (VSC) silicon semiconductor rectifier systems, such as insulated gate bipolar transistors (IGBT) and gate turn-off thyristors (GTO), have made smaller high voltage DC power transmission systems economical. All of these devices function as rectifiers.


title: Rectifier

text: Active rectification is a technique for improving the efficiency of rectification by replacing diodes with actively controlled switches such as transistors, usually power MOSFETs or power BJTs. Whereas normal semiconductor diodes have a roughly fixed voltage drop of around 0.5-1 volts, active rectifiers behave as resistances, and can have arbitrarily low voltage drop.


title: Rectifier

text: Historically, vibrator driven switches or motor-driven commutators have also been used for mechanical rectifiers and synchronous rectification.


title: Rectifier

text: Active rectification has many applications. It is frequently used for arrays of photovoltaic panels to avoid reverse current flow that can cause overheating with partial shading while giving minimum power loss.


title: Rectifier

text: A major area of research is to develop higher frequency rectifiers, that can rectify into terahertz and light frequencies. These devices are used in optical heterodyne detection, which has myriad applications in optical fiber communication and atomic clocks. Another prospective application for such devices is to directly rectify light waves picked up by tiny antennas, called nantennas, to produce DC electric power. It is thought that arrays of antennas could be a more efficient means of producing solar power than solar cells.


title: Rectifier

text: A related area of research is to develop smaller rectifiers, because a smaller device has a higher cutoff frequency. Research projects are attempting to develop a unimolecular rectifier, a single organic molecule that would function as a rectifier.


title: Susan Hayward

text: Susan Hayward (born Edythe Marrenner; June 30, 1917 – March 14, 1975) was an American film actress, best known for her film portrayals of women that were based on true stories.


title: Susan Hayward

text: After working as a fashion model for the Walter Thornton Model Agency, Hayward traveled to Hollywood in 1937 to audition for the role of Scarlett O'Hara. She secured a film contract and played several small supporting roles over the next few years.


title: Susan Hayward

text: By the late 1940s, the quality of her film roles improved, and she achieved recognition for her dramatic abilities with the first of five Academy Award for Best Actress nominations for her performance as an alcoholic in "Smash-Up, the Story of a Woman" (1947). Hayward's success continued through the 1950s as she received nominations for "My Foolish Heart" (1949), "With a Song in My Heart" (1952), and "I'll Cry Tomorrow" (1955), winning the Academy Award for her portrayal of death row inmate Barbara Graham in "I Want to Live!" (1958). For her performance in "I'll Cry Tomorrow" she won the Cannes Film Festival Award for Best Actress.


title: Susan Hayward

text: After Hayward's second marriage and subsequent move to Georgia, her film appearances became infrequent; although she continued acting in film and television until 1972. She died in 1975 of brain cancer.


title: Susan Hayward

text: Hayward was born Edythe Marrenner on June 30, 1917, in the Brooklyn borough of New York City, the youngest of three children to Ellen (née Pearson; 1888–1958) and Walter Marrenner (1879–1938). Her mother was of Swedish descent. She had an older sister, Florence, and an older brother, Walter, Jr. In 1924, Marrenner was hit by a car, suffering a fractured hip and broken legs that put her in a partial body cast with the resulting bone setting leaving her with a distinctive hip swivel later in life.


title: Susan Hayward

text: Hayward was educated at Public School 181 and graduated from the Girls' Commercial High School in June 1935 (later renamed Prospect Heights High School). According to the Erasmus Hall High School alumni page, Hayward attended that school in the mid-1930s, although she only recollected swimming at the pool for a dime during hot summers in Flatbush, Brooklyn. During her high school years, she acted in various school plays, and was named "Most Dramatic" by her class.


title: Susan Hayward

text: Hayward began her career as a model, traveling to Hollywood in 1937 to try out for the role of Scarlett O'Hara in "Gone with the Wind". Though Hayward did not get the part, she was used for other actors' screen tests by David Selznick and received a contract at Warner Bros.


title: Susan Hayward

text: Talent agent Max Arnow changed Marrenner's name to Susan Hayward once she started her six-month contract for $50 a week with Warner's. Hayward had bit parts in "Hollywood Hotel" (1937), "The Amazing Dr. Clitterhouse" (1938) (her part was edited out), and "The Sisters" (1938), as well as in a short, "Campus Cinderella" (1938).


title: Susan Hayward

text: Hayward's first sizeable role was with Ronald Reagan in "Girls on Probation" (1938), where she was a strong 10th in billing. She was also in "Comet Over Broadway" (1938), but returned to unbilled and began posing for pinup "cheesecake" publicity photos, something she and most actresses despised, but under her contract she had no choice. With Hayward's contract at Warner Bros. finished, she moved on to Paramount Studios.


title: Susan Hayward

text: In 1939, Paramount Studios signed her to a $250 per week contract. Hayward had her first breakthrough in the part of Isobel in "Beau Geste" (1939) opposite Gary Cooper and Ray Milland. She held the small, but important, haunting love of youth role as recalled by the Geste brothers while they searched for a valuable sapphire known as "the blue water" during desert service in the Foreign Legion; the film was hugely successful.


title: Susan Hayward

text: Paramount put Hayward as the second lead in "Our Leading Citizen" (1939) with Bob Burns and she then supported Joe E. Brown in "$1000 a Touchdown" (1939).


title: Susan Hayward

text: Hayward went to Columbia for a supporting role alongside Ingrid Bergman in "Adam Had Four Sons" (1941), then to Republic Pictures for "Sis Hopkins" (1941) with Judy Canova and Bob Crosby. Back at Paramount, she had the lead in a "B" film, "Among the Living" (1941).


title: Susan Hayward

text: Cecil B. De Mille gave her a good supporting role in "Reap the Wild Wind" (1942), to costar with Milland, John Wayne and Paulette Goddard. She was in the short "A Letter from Bataan" (1942) and supported Goddard and Fred MacMurray in "The Forest Rangers" (1942).


title: Susan Hayward

text: Hayward costarred in "I Married a Witch" (1942) with Fredric March and Veronica Lake, as the fiancé of Wallace Wooly (March) before Lake's witch reappears from a Puritanical stake burning 300 years earlier. The film served as inspiration for the 1960s TV series "Bewitched" and was based on an unfinished novel by Thorne Smith. It was made for Paramount but was sold to United Artists. She was next in Paramount's all-star musical review "Star Spangled Rhythm" (1943) that also featured its nonmusical contract players.


title: Susan Hayward

text: Hayward appeared with William Holden in "Young and Willing" (1943), a Paramount film distributed by UA. She was in Republic's "Hit Parade of 1943" (1943), her singing voice dubbed by Jeanne Darrell.


title: Susan Hayward

text: Sam Bronston borrowed her for "Jack London" (1943) at UA. At Republic she was Wayne's love interest in "The Fighting Seabees" (1944), the biggest budgeted film in that company's history.


title: Susan Hayward

text: She starred in the film version of "The Hairy Ape" (1944) for UA. Back at Paramount she was Loretta Young's sister in "And Now Tomorrow" (1944). She then left the studio.


title: Susan Hayward

text: RKO gave Hayward her first top billing in "Deadline at Dawn" (1946), a Clifford Odets written Noir film, which was Harold Clurman's only movie as director.


title: Susan Hayward

text: After the war, Hayward's career took off when producer Walter Wanger signed her for a seven-year contract at $100,000 a year. Her first film was "Canyon Passage" (1946).


title: Susan Hayward

text: In 1947, she received the first of five Academy Award nominations for her role as an alcoholic nightclub singer based on Dixie Lee in "Smash-Up, the Story of a Woman", her second film for Wanger. Although it was not well received by critics, it was popular with audiences and a box office success, launching Hayward as a star.


title: Susan Hayward

text: RKO used her again for "They Won't Believe Me" (1947). She subsequently worked for Wanger on "The Lost Moment" (1948) and "Tap Roots" (1948). Both films lost money but the latter was widely seen.


title: Susan Hayward

text: At Universal Hayward was in "The Saxon Charm" (1948) and she did "Tulsa" (1949) for Wanger. Both films were commercial disappointments.


title: Susan Hayward

text: Hayward went over to 20th Century Fox to make "House of Strangers" (1949) for director Joseph Mankiewicz, beginning a long association with that studio.


title: Susan Hayward

text: Sam Goldwyn borrowed her for "My Foolish Heart" (1949), which earned her an Oscar nomination, then she went back to Fox for "I'd Climb the Highest Mountain" (1951), which was a hit.


title: Susan Hayward

text: She stayed at that studio to make the western "Rawhide" (1951) with Tyrone Power, and the romantic drama "I Can Get It for You Wholesale" (1951).


title: Susan Hayward

text: Hayward then starred in three massive successes: "David and Bathsheba" (1951) with Gregory Peck, the most popular film of the year; "With a Song in My Heart" (1952), a biopic of Jane Froman, which earned her an Oscar nomination; and "The Snows of Kilimanjaro" (1952), with Peck and Ava Gardner.


title: Susan Hayward

text: RKO borrowed Hayward for "The Lusty Men" (1952) with Robert Mitchum, then she went back to Fox for "The President's Lady" (1953), playing Rachel Jackson alongside Charlton Heston; "White Witch Doctor" (1953) again a costar with Mitchum; "Demetrius and the Gladiators" (1954), as Messalina; "Garden of Evil" (1954) with Gary Cooper and Richard Widmark; and "Untamed" (1955) with Tyrone Power. Hayward then starred with Clark Gable in "Soldier of Fortune" (1955), a CinemaScope film that was a box office miss.


title: Susan Hayward

text: MGM hired Hayward to play the alcoholic showgirl/actress Lillian Roth in "I'll Cry Tomorrow" (1955), based on Roth's best-selling autobiography of the same title, for which she received a Cannes award. It was a major financial success.


title: Susan Hayward

text: Although Hayward never truly became known as a singer—she disliked her own singing–she portrayed singers in several films. However, in "I'll Cry Tomorrow"—whose vocals were once widely attributed to professional ghost singer Marni Nixon—Hayward sang the vocals undubbed and appears on the soundtrack. Hayward performed in the musical biography of singer Jane Froman in the 1952 film, "With a Song in My Heart", a role which won her the Golden Globe for Best Actress Actress In A Leading Role – Musical Or Comedy. Jane Froman's voice was recorded and used for the film as Hayward acted out the songs.


title: Susan Hayward

text: In 1956, she was cast by Howard Hughes to play Bortai in the historical epic "The Conqueror", as John Wayne's leading lady. It was critically deprecated but a commercial success. She did a comedy with Kirk Douglas, "Top Secret Affair" (1956) which flopped.


title: Susan Hayward

text: Hayward's last film with Wanger, "I Want to Live!" (1958), in which she played death row inmate Barbara Graham, was a critical and commercial success and won Hayward the Academy Award for Best Actress for her portrayal. Many movie pundits have referred to her performance in I Want To Live as the greatest Hollywood acting performance ever, of any actress, of all time. Bosley Crowther of "The New York Times" wrote that her performance was "so vivid and so shattering ... Anyone who could sit through this ordeal without shivering and shuddering is made of stone." Hayward received 37% of the film's net profits.


title: Susan Hayward

text: Hayward made "Thunder in the Sun" (1959) with Jeff Chandler, a mediocre wagon train picture about French Basque pioneers, which was a modest success financially, and then "Woman Obsessed" (1959) at Fox.


title: Susan Hayward

text: In 1961, Hayward starred as a shrewd working girl who becomes the wife of the state's next governor (Dean Martin) and ultimately takes over the office herself in "Ada". The same year, she played Rae Smith in Ross Hunter's lavish remake of "Back Street", which also starred John Gavin and Vera Miles. Neither film was particularly successful; nor were "I Thank a Fool" (1962) at MGM, "Stolen Hours" (1963), and "Where Love Has Gone" (1964), which co-starred Bette Davis.


title: Susan Hayward

text: Hayward was reunited with Joseph Mankiewicz in "The Honey Pot" (1967). Then she replaced Judy Garland as Helen Lawson in the film adaptation of Jacqueline Susann's "Valley of the Dolls" (1967), which drew terrible reviews but made money at the box office.


title: Susan Hayward

text: She received good reviews for her performance at Caesars Palace in the Las Vegas production of "Mame" that opened in December 1968. She was replaced by Celeste Holm in March 1969 after her voice gave out and she had to leave the production.


title: Susan Hayward

text: She appeared in the TV movie "Heat of Anger" (1972) and the western film "The Revengers" (1972) with William Holden.


title: Susan Hayward

text: Her final film role was as Dr. Maggie Cole in the 1972 made-for-TV drama "Say Goodbye, Maggie Cole". Intended to be the pilot episode for a television series, "Maggie Cole" was never produced because of Hayward's failing health. Her last public appearance was at the Academy Awards telecast in 1974 to present the Best Actress award despite being very ill. With Charlton Heston's support, she was able to present the award.


title: Susan Hayward

text: During World War II, Hayward supported the war effort by volunteering at the Hollywood Canteen, where she met her first husband, actor Jess Barker. They married on July 23, 1944, and on February 19, 1945, fraternal twin sons named Gregory and Timothy were born. The marriage was turbulent, with a judge granting an interlocutory divorce decree on August 17, 1954. During the contentious divorce proceedings, Hayward stayed in the United States rather than join the Hong Kong location shoot for the film "Soldier of Fortune." She shot her scenes on a sound stage with co-star Clark Gable in Hollywood. A few brief, distant scenes of Gable and a Hayward double walking near landmarks in Hong Kong were combined with the indoor shots. By April 1955, the stress of divorce proceedings and overwork prompted a suicide attempt.


title: Susan Hayward

text: In 1957, Hayward married Floyd Eaton Chalkley, commonly known as Eaton Chalkley, a successful Georgia rancher and businessman who had worked as a federal agent. The marriage was a happy one. They lived on a farm near Carrollton, Georgia, and owned property across the state line in Cleburne County, just outside Heflin, Alabama. She became a popular figure in the area in the late 1950s. In December 1964, she and her husband were baptized Catholic by Father Daniel J. McGuire at SS. Peter and Paul's Roman Catholic Church on Larimer Avenue, in the East Liberty section of Pittsburgh, fulfilling a promise made in China to McGuire, that if she ever converted, he would be the one to baptize her. Chalkley died on January 9, 1966. Hayward went into mourning and did little acting for several years. She took up residence in Florida, because she preferred not to live in her Georgia home without her husband.


title: Susan Hayward

text: Before her Catholic baptism, Hayward had been a proponent of astrology. She particularly relied on the advice of Carroll Righter, who called himself "the Gregarious Aquarius" and the self-proclaimed "Astrologer to the Stars", who informed her that the optimal time to sign a film contract was exactly 2:47 a.m., causing her to set her alarm for 2:45 so she could be sure to obey his instructions.


title: Susan Hayward

text: Hayward's doctor found a lung tumor in March 1972 that metastasized, and after a seizure in April 1973, she was diagnosed with brain metastases. On March 14, 1975, she suffered a seizure in her Beverly Hills home and died at the age of 57. A funeral service was held on March 16 at Our Lady of Perpetual Help Roman Catholic Church in Carrollton, Georgia. Hayward's body was buried in the church's cemetery.


title: Susan Hayward

text: Theories about the radioactive fallout from atmospheric atomic bomb tests surround the making of "The Conqueror" in St. George, Utah. Several production members, including Hayward, John Wayne, Agnes Moorehead, Pedro Armendáriz (who committed suicide after a diagnosis of cancer), and director Dick Powell later succumbed to cancer and cancer-related illnesses. As ascertained by "People" magazine in 1980, out of a cast and crew totaling 220 people, 91 of them developed some form of cancer, and 46 had died of the disease.


title: Grade (climbing)

text: In rock climbing, mountaineering, and other climbing disciplines, climbers give a grade to a climbing route or boulder problem, intended to describe concisely the difficulty and danger of climbing it. Different types of climbing (such as sport climbing, bouldering or ice climbing) each have their own grading systems, and many nationalities developed their own, distinctive grading systems.


title: Grade (climbing)

text: There are a number of factors that contribute to the difficulty of a climb, including the technical difficulty of the moves, the strength, stamina and level of commitment required, and the difficulty of protecting the climber. Different grading systems consider these factors in different ways, so no two grading systems have an exact one-to-one correspondence.


title: Grade (climbing)

text: Climbing grades are inherently subjective. They may be the opinion of one or a few climbers, often the first ascensionist or the authors of a guidebook. A grade for an individual route also may be a consensus reached by many climbers who have climbed the route. While grades are usually applied fairly consistently across a climbing area, there are often perceived differences between grading at different climbing areas. Because of these variables, a given climber might find a route to be either easier or more difficult than expected for the grade applied.


title: Grade (climbing)

text: In 1894, the Austrian mountaineer Fritz Benesch introduced the first known grading system for rock climbing. The Benesch scale had seven levels of difficulty, with level VII the easiest and level I the most difficult. Soon more difficult climbs were made, which originally were graded level 0 and 00. In 1923, the German mountaineer Willo Welzenbach compressed the scale and turned the order around, so that level 00 became level IV–V. This "Welzenbach scale" was adopted in 1935 by French mountaineers like Lucien Devies, Pierre Allain and Armand Charlet for routes in the Western Alps and finally in 1947 in Chamonix by the Union Internationale des Associations d'Alpinisme. It prevailed internationally and was renamed in 1968 as the UIAA scale. Originally a 6-grade scale, it has been officially open-ended since 1979.


title: Grade (climbing)

text: For free climbing, there are many different grading systems varying according to country. They include:


title: Grade (climbing)

text: The Yosemite Decimal System (YDS) of grading routes was initially developed as the Sierra Club grading system in the 1930s to rate hikes and climbs in the Sierra Nevada range. The rock climbing portion was developed at Tahquitz Rock in southern California by members of the Rock Climbing Section of the Angeles Chapter of the Sierra Club in the 1950s. It quickly spread to Canada and the rest of the Americas.


title: Grade (climbing)

text: Originally a single-part classification system, grade and protection rating categories were added later. The new classifications do not apply to every climb and usage varies widely.


title: Grade (climbing)

text: When a route also involves aid climbing, its unique aid designation can be appended to the YDS free climbing rating. For example, the North America Wall on El Capitan would be classed "VI, 5.8, A5[2]", or Medlicott Dome – Bachar/Yerian 5.11c (X,***)


title: Grade (climbing)

text: The system consists of five classes indicating the technical difficulty of the hardest section. Class 1 is the easiest and consists of walking on even terrain. Class 5 is climbing on vertical or near-vertical rock, and requires skill and a rope to proceed safely. Un-roped falls would result in severe injury or death. Originally, Class 6 was used to grade aid climbing. However, the separate A (aid) rating system became popular instead.


title: Grade (climbing)

text: The original intention was that the classes would be subdivided decimally, so that a route graded 4.5 would be a scramble halfway between 4 and 5, and 5.9 would be the hardest rock climb. Increased standards and improved equipment meant that climbs graded 5.9 in the 1960s are now only of moderate difficulty. Rather than regrade all climbs each time standards improve, additional grades were added at the top—originally only 5.10, but it soon became apparent that an open-ended system was needed, and further grades of 5.11, 5.12, etc. were added, and thus the system is no longer decimal.


title: Grade (climbing)

text: While the top grade was 5.10, a large range of climbs in this grade was completed, and climbers realized a subdivision of the upper grades was required. Letter grades were added for climbs at 5.10 and above by adding a letter "a" (easiest), "b", "c", or "d" (hardest).


title: Grade (climbing)

text: The system originally considered only the technical difficulty of the hardest move on a route. For example, a route of mainly 5.7 moves but with one 5.11b move would be graded 5.11b and a climb that consisted of 5.11b moves all along its route would also be 5.11b. Modern application of climbing grades, especially on climbs at the upper end of the scale (>5.10), also consider how sustained or strenuous a climb is, in addition to the difficulty of the single hardest move.


title: Grade (climbing)

text: The YDS system involves an optional Roman numeral grade that indicates the length and seriousness of the route. The Grade is more relevant to mountaineering and big wall climbing, and usually not stated when talking about short rock climbs. The grades range from grade I to VI spanning a one-hour climb to a multi-day climb respectively.


title: Grade (climbing)

text: III: Requires most of a day perhaps including the approach, which may require winter travel skills (possible avalanche terrain, placing descent anchors). The East Buttress route on Mount Whitney is a grade III, yet it requires of technical climbing and a total vertical gain of over from trail head to summit. Only a minority of climbers, the most fit and seasoned, could do this route car to car in a day. Other grade III climbs, such as Cathedral Peak in Tuolumne, are typically done in one day.


title: Grade (climbing)

text: IV: A multipitch route at higher altitude or remote location, which may involve multi-hour approaches in serious alpine terrain. A predawn start is usually indicated, and unforeseen delays can lead to unplanned bivouacs high on the route.


title: Grade (climbing)

text: V: A multi-day climbing adventure for all but an elite few. The route Dark Star, on Temple Crag, is grade V and involves a approach and over , 30 pitches of technical climbing.


title: Grade (climbing)

text: VI: A multi-day climbing adventure for (nearly) all. Peter Croft saves this grade for the full Palisade Traverse, a massive route which includes six summits and miles of technical climbing. He states, "This is the only route in this book that I haven't completed in a single push, although I've done all the crux sections at various times." Although most grade VIs are alpine climbs, The Nose on El Capitan is an example of a technical grade VI route. It has of either very hard technical climbing or easier aid climbing and takes most climbers 2–7 days, although a few climbers have freed it in a day, and more have aided it in a day.


title: Grade (climbing)

text: An optional protection rating indicates the spacing and quality of the protection available, for a well-equipped and skilled leader. The letter codes chosen were, at the time, identical to the American system for rating the content of movies. Grades range from solid protection, G (Good), to no protection, X. The G and PG (Pretty Good) ratings are often left out, as being typical of normal, everyday climbing. PG13 ratings are occasionally included. R (Run-out) and X (eXtreme) climbs are usually noted as a caution to the unwary leader. Application of protection ratings varies widely from area to area and from guidebook to guidebook.


title: Grade (climbing)

text: The British grading system for traditional climbs, also known as the UK grading system, used in Great Britain and Ireland, has (in theory) two parts: the adjectival grade and the technical grade.


title: Grade (climbing)

text: Sport climbing in Britain and Ireland uses the French grading system, often prefixed with the letter "F".


title: Grade (climbing)

text: The adjectival grade attempts to assess the overall difficulty of the climb – taking into account all factors which lend difficulty to a pitch including technical difficulty, sustainedness, protection quality, rock quality, exposure and other less tangible aspects – for a climber leading the route on sight in traditional style. It thus resembles mountaineering grades such as the International French Adjectival System. The adjectival grade appears to have been introduced in the early 20th century by O. G. Jones, who classified climbs as “Easy”; “Moderate”; “Difficult” or “Exceptionally Severe”. Increasing standards have several times led to extra grades being added. The adjectival grades are as follows:


title: Grade (climbing)

text: Increasing standards in the 1970s resulted in the adoption of Pete Botterill's proposal that the Extremely Severe grade be subdivided in an open-ended fashion into E1 (easiest), E2, E3 and so on. The E-grade is still an estimation of overall difficulty experienced by a climber leading a route on-sight.


title: Grade (climbing)

text: In 2006 the hardest grade claimed was E11 for "Rhapsody" on Dumbarton Rock, climbed by Dave MacLeod, featured French 8c/+ climbing with the potential of a 20-metre fall onto a small wire. In August 2008, MacLeod completed a new project close to Tower Ridge on Ben Nevis called 'Echo Wall'. He left the route ungraded, saying only that it was 'harder than Rhapsody'. Many climbers consider such high grades provisional, as the climbs have not yet been achieved on-sight/ground-up.


title: Grade (climbing)

text: The grade "XS" (occasionally qualified by Mild [MXS] and Hard [HXS]) is sometimes used for eXtremely Severe rock climbs when a high proportion of the challenge is due to objective dangers, typically loose or crumbling rock, rather than technical difficulty.


title: Grade (climbing)

text: The technical grade attempts to assess only the technical climbing difficulty of the hardest move or short sequence of moves on the route, without regard to the danger of the move or the stamina required if there are several such moves in a row. Technical grades are open-ended, starting at 1 and subdivided into "a", "b" and "c", but are rarely used below 3c. The technical grade was originally a bouldering grade introduced from Fontainebleau by French climbers.


title: Grade (climbing)

text: Usually the technical grade increases with the adjectival grade, but a hard technical move that is well protected (that is, notionally safe) may not raise the standard of the adjectival grade very much. VS 4c might be a typical grade for a route. VS 4a might indicate very poor protection (easy moves, but no gear) or extremely sustained (every move is 4a and the climbing is steep/strenuous whilst reasonably protected), while VS 5b would usually indicate one crux move of 5b that is the first move or very well protected and the rest of the climb without much difficulty. On multi-pitch routes it is usual to give the overall climb an adjectival grade and each pitch a separate technical grade (such as HS 4b, 4a).


title: Grade (climbing)

text: The UIAA grading system is mostly used for short rock routes in Germany, Austria, Switzerland, Czech Republic, Slovakia and Hungary. On long routes it is often used in the Alps and Himalaya. Using Roman numerals, it was originally intended to run from I (easiest) to VI (hardest), but as with all other grading systems, improvements to climbing standards have led to the system being open-ended after the grade VII was accepted in 1977. An optional + or − may be used to further differentiate difficulty. As of 2016, the hardest climbs are XII.


title: Grade (climbing)

text: In the '70s, in Poland, the UIAA scale was in use, when climbing limestone rocks near Cracow, where Polish sport climbing was developed. Grade-I route was considered a walk, while Grade-VI was described as "hardest". As climbing level was growing, the scale seemed more and more inadequate. Famous climber and alpinist Wojciech Kurtyka proposed an extension to the scale. Simpler routes were described as it was before - using Roman numerals. Harder ones - using Arabic numerals after Roman VI. Hence, after traditional VI+ came VI.1, VI.1+, VI.2 and so on. Currently, the hardest route graded in Cracow Scale is "Stal Mielec" in Mamutowa cave, Jura Krakowsko-Czestochowska, graded as VI.8+.


title: Grade (climbing)

text: In Sweden, Norway, and Finland, they originally used the UIAA scale. But since it was thought that 6+ would be the definition of how hard humans could climb, no climber wanted to put up this grade, leaving the entire scale very sand-bagged compared to the UIAA scale. To show that it is a Scandinavian grade, Arabic numerals are used (e.g. 5, 6, 7), and for UIAA graded climbs in Scandinavia, Roman numerals are used (e.g. V, VI, VII). In some guide books, where many Germans have done the first ascent, the UIAA scale is used for those climbs, and where the first ascent is done by a Scandinavian, the Scandinavian scale is used. The only way to know how the climb is rated is to know whether the first person to ascend was German or Scandinavian. In sport climbing the French scale is pretty common (especially for the hardest grades), or both scales are used in the guide book, with the other scale in parentheses, i.e. 6+ (6b).


title: Grade (climbing)

text: The Saxon grading system () is used in the Free State of Saxony in Germany and in a derivative form in some areas in the Czech Republic under the name (). It was developed in the beginning of the 20th century for the formidable Saxon Switzerland climbing region and was gradually adopted within other climbing areas in the region, such as Bohemian Switzerland, Bohemian Paradise, Lusatian Mountains, and the Zittau Mountains.


title: Grade (climbing)

text: Due to the climbing particularities of the region and the territorial and political division of Germany in 1945–1990 the system developed independently from other grading systems in Germany. During this time it was also sometimes referred to as the "East German System".


title: Grade (climbing)

text: The Saxon grades use Roman numerals to denote the level of difficulty and subdivisions from grade VII onwards with the aid of the letter "a", "b" and "c"; "XIc" is currently the highest grade. In addition the system accounts for horizontal jumps with Arabic numerals between 1 and 7.


title: Grade (climbing)

text: The French numerical system (distinct from the adjectival system, described later) rates a climb according to the overall technical difficulty and strenuousness of the route. Grades start at 1 (very easy) and the system is open-ended. Each numerical grade can be subdivided by adding a letter ("a", "b" or "c"). Examples: 2, 4, 4b, 6a, 7c. An optional + may be used to further differentiate difficulty. For example, these routes are sorted by ascending difficulty: 5c+, 6a, 6a+, 6b, 6b+. Although some countries in Europe use a system with similar grades but not necessarily matching difficulties, the French system remains the main system used in the vast majority of European countries and in many international events outside the US.


title: Grade (climbing)

text: The Brazilian grade system for sport climbing is similar to the French system, but uses roman numerals with a few adjustments: grades I to II are very easy (II being a very steep, but almost walkable route), III to V are easy (III being the grade most indoor gyms use as a starting point for beginners) and it progresses till the maximum grade of XIII, as of 2020. Grades below VII are subdivided differently depending on the geographical location of the crag:


title: Grade (climbing)

text: The Brazilian system has a remarkably detailed grading system for traditional climbing, which due to the geology in the country consists mostly of long, bolted/mixed routes instead of pure crack climbing. The basic structure is given in the example below.


title: Grade (climbing)

text: It is important to keep in mind that all the items in the grading system are independent. One can then have grades like "D4 4º VIIc A3 E3", or "D1 7º VIIc (A0/VIIIb) E1". The first route takes a whole day to be climbed, mostly on easy terrain, but with some serious aid and a very hard crux (when compared to the general grade) that cannot be bypassed by aiding. The second route, on the other hand, has much harder free climbing than the first one, but is safer, shorter and a crux that can be aid climbed as an A0.


title: Grade (climbing)

text: The Ewbank system, used in Australia, New Zealand, and South Africa, was developed in the mid 1960s by John Ewbank. Ewbank also developed an open ended “M” system for aid climbing. The numerical Ewbank system is open-ended, starting from 1, which one can (at least in theory) walk up, to the six climbs located in Australia given the hardest currently confirmed grade of 35. South African and Australian grades differ by 1 or 2 grade points.


title: Grade (climbing)

text: The Ewbank system is not intended to simply grade the hardest individual move on a climb though the grading system is often described this way. Ewbank explained "Grading takes the following into consideration: Technical difficulty, exposure, length, quality of rock, protection and other smaller factors. As these are more or less all related to each other, I have rejected the idea of 3 or 4 grades, i.e. one for exposure, one for technical difficulty, one for protection etc. Instead the climb is given its one general grading, and if any of the other factors is outstanding, this is stated verbally in the short introduction to that climb"


title: Grade (climbing)

text: The current practice is to make mention of all factors affecting the climber's experience (exposure, difficulty of setting protection or outright lack of protection) in the description of the climb contained in the guide.


title: Grade (climbing)

text: Researchers have demonstrated that the difficulty of climbing routes can be predicted using statistical models and machine learning techniques. A Bradley-Terry model based on historical ascents generated ratings on an interval scale that were correlated with grades from the Ewbank system. A different approach, using a variable-order Markov model with a description of the sequence of climbing moves, was unable to correctly predict difficulty.


title: Grade (climbing)

text: There are several systems in use to grade mountain climbs. Alpine mountaineering routes are usually graded based on all of their different aspects, as they can be very diverse. Thus, a mountain route may be graded 5.6 (rock difficulty), A2 (aid difficulty), WI3 (ice climbing difficulty), M5 * (mixed climbing difficulty), 70 degrees (steepness), (length), VI (commitment level), and many other factors. See also Summitpost Alpine Grades.


title: Grade (climbing)

text: In contrast to the French numerical system (described earlier), the French adjectival alpine system evaluates the overall difficulty of a route, taking into consideration the length, difficulty, exposure and commitment-level of the route (i.e., how hard it may be to retreat). The overall grade combines altitude; length and difficulty of approach and descent; number of difficult pitches and how sustained they are; exposure; and quality of rock, snow and ice. These are, in increasing order:


title: Grade (climbing)

text: Often a + (pronounced "Sup" for "supérieur") or a − (pronounced "Inf" for "inférieur") is placed after the grade to indicate if a particular climb is at the lower or upper end of that grade (e.g., a climb slightly harder than "PD+" might be "AD−").


title: Grade (climbing)

text: In communist times, alpine climbs were graded in a system adapting Russian grades to local conditions, by leaving out route altitude and approach difficulties (since all Romanian alpine climbs are accessible in a day, and below 2600m).


title: Grade (climbing)

text: However, the system has two large problems. The first is the obscure mix of technical difficulty and length/commitment, which leads to highly different routes, even in the same area, having the same grade; for example, in Bicaz, both Creasta Estica a Pietrei Altarului, a beginner-friendly ridge with five out of six pitches of UIAA 4 terrain (assuming the one aid move is taken as such) and one of easy UIAA 6, and Fisura Centrala, a two-pitch UIAA 7 crack climb, are 4As. The second is the integration with the Communist-era competitional system that led to grades varying quite a bit from area to area – a Bicaz 6 will be easier than a Bucegi 6, for example. Because of this, modern documentation also usually contains the UIAA/French free-climbing rating of the crux of the route, as well as the aid-climbing rating (in the original aid-climbing grading system) + the mandatory climbing rating – so, for example, the direct Fisura Albastra is a 8+ (6+ A1).


title: Grade (climbing)

text: An alpine grading system adapted from the grades used in the Aoraki/Mt Cook Region is widely used in New Zealand for alpine routes in the North and South islands. Grades currently go from 1–7. The grading system is open ended; harder climbs are possible. Factors which determine grade are (in descending order of contributing weight): technical difficulty, objective danger, length and access.


title: Grade (climbing)

text: In the Alaskan grading system, mountaineering climbs range from grade 1–6, and factor in difficulty, length, and commitment. The hardest, longest routes are Alaskan grade 6. The system was first developed by Boyd N. Everett, Jr. in 1966, and is supposed to be particularly adapted to the special challenges of Alaskan climbing. Here is a summary of Alaska grade descriptors, adapted (and greatly simplified) from "Alaska: A Climbing Guide", by Michael Wood and Colby Coombs (The Mountaineers, 2001):


title: Grade (climbing)

text: A plus (+) may be added to indicate somewhat higher difficulty. For example, the West Buttress Route on Denali is graded 2+ in the above-mentioned guidebook.


title: Grade (climbing)

text: Importantly, even an Alaska Grade 1 climb may involve climbing on snow and glaciers in remote locations and cold weather.


title: Grade (climbing)

text: In post USSR countries, there is Russian grading system, it includes range from grade 1A–6B, and factor in difficulty, altitude, length, and commitment like in Alaskan.


title: Grade (climbing)

text: This system measures the difficulty of routes on water ice. The WI scale spans grades from 1 to 7. There also exists a rating scale for Alpine Ice (compacted snow or glacial ice) that has the same rating system as the "WI" system, but is instead denoted by "AI." The primary difference between the two is the density of the ice, Water Ice being much more dense.


title: Grade (climbing)

text: WI2 – low-angled (60 degree consistent ice), with good technique can be easily climbed with one ice axe. Grades beyond this generally require the use of two ice tools.


title: Grade (climbing)

text: WI3 – generally sustained in the 60–70 degree range with occasional near-vertical steps up to 4 metres (Cascade Waterfall, Banff; This House of Sky, Ghost River)


title: Grade (climbing)

text: WI4 – near-vertical steps of up to 10 metres, generally sustained climbing requiring placing protection screws from strenuous stances (Professor's Falls, Banff; Weeping Wall Left, Icefields Parkway, Banff; Silk Tassle, Yoho; Moonlight & Snowline, Kananskis)


title: Grade (climbing)

text: WI5 – near-vertical or vertical steps of up to 20 metres, sustained climbing requiring placing multiple protection screws from strenuous stances with few good rests (Carlsberg Column, Field; The Sorcerer, Ghost River; Bourgeau Left Hand, Banff)


title: Grade (climbing)

text: WI5+ – highly technical WI5 (Oh le Tabernac, Icefield Parkway; Hydrophobia, Ghost River; Sacre Bleu, Banff)


title: Grade (climbing)

text: WI6 – vertical climbing for the entire pitch (e.g. 30–60 metres) with no rests. Requires excellent technique and/or a high level of fitness (The Terminator, Banff; Nemesis, Kootenay Park; Whiteman Falls, Kananaskis Country; Riptide, Banff)


title: Grade (climbing)

text: WI6+ – vertical or overhanging with no rests, and highly technical WI6 (Fosslimonster, Norway; French Maid, Yoho; French Reality, Kootenay Park)


title: Grade (climbing)

text: WI7–WI9 – sustained and overhanging with no rests. Rare and widely accepted testpieces. Note that routes (e.g. Sea of Vapours, Banff; Riptide, Icefield Parkway, Banff) have been assigned WI7− to WI7+ but have been subsequently downgraded in later years as they don't meet the strict criteria of difficulty.


title: Grade (climbing)

text: Modern ice-climbers have established even more severe grades for waterfall ice climbs that are largely severely overhanging, notable milestones being:


title: Grade (climbing)

text: WI12 – "Interstellar Spice" (first W12 climbed by Tim Emmett and Klemen Premrl in 2016 at Helmcken Falls).


title: Grade (climbing)

text: This measures the difficulty of mixed climbs combining ice and rock. Mixed climbs have recently been climbed and graded as high as M14.


title: Grade (climbing)

text: In the British Isles, the Scottish winter grading system is used for both ice and mixed climbs. Originally the system had just an overall grade given in Roman numerals running up to VI, but this has been refined and extended. Routes are given two grades, essentially equivalent to the adjectival and technical grades used in British traditional climbing. Overall difficulty is signified by a Roman numeral, and the technical difficulty of the hardest move or section of the climb is graded with an Arabic numeral. For routes of grade I – III, the technical grade is usually omitted unless it is 4 or greater. As with other grading systems, advances in climbing have led to the acceptance of an open-ended grading system (the new grades previously finished at IX, 9), and climbs have now been graded up to XII, 12.


title: Grade (climbing)

text: Aid climbs are graded A0 to A5 depending on the reliability of the gear placements and the consequences of a fall. New routes climbed today are often given a “New Wave” grade using the original symbols but with new definitions. Depending on the area in question, the letter “A” may mean that the use of pitons (or other gear that requires the use of a hammer) is needed to ascend the route. The letter “C” explicitly indicates that the route can be climbed clean (clean climbing) without the use of a hammer.


title: Grade (climbing)

text: The 'C' scale adopts "New Wave" definitions. Clean aiding is aid climbing without the use of bolting gear, pitons or other gear that scars the rock or becomes fixed after the ascent. Most difficult aid climbs still require pitons or other techniques using a hammer, and are thus rated on the "New Wave" 'A' scale past a certain point.


title: Grade (climbing)

text: As mentioned above, grading is a subjective task and no two grading systems have an exact one-to-one correspondence. Therefore, there is not a perfect agreement in the literature about grading system comparisons or conversion rules.


title: Grade (climbing)

text: The British Adj grades (E) do not grade only the hardness of the climb but the overall feel of the route, i.e., how hard gear is to place, how good is the gear, how high up is the first piece of gear, the possibility and severity of a ground fall, and how dangerous the climb is. All these factors are regarded when giving it the grade.


title: Grade (climbing)

text: The following grades are used for rating boulder problems throughout the world. Although fundamental differences in climbing style make direct comparison between bouldering and route climbing difficult, the colors in the above and below tables correspond to roughly equivalent sets of grades.


title: Paz de la Huerta

text: María de la Paz Elizabeth Sofía Adriana de la Huerta y Bruce (; born September 3, 1984), known professionally as Paz de la Huerta, is an American actress and model. She had roles in the films "The Cider House Rules" (1999) and "A Walk to Remember" (2002), and played Lucy Danziger in the HBO drama series "Boardwalk Empire".


title: Paz de la Huerta

text: De la Huerta was raised by her mother, with her older sister, in the New York City neighborhood of SoHo, located in Lower Manhattan. Her parents are Spanish nobleman Íñigo de la Huerta y Ozores, 14th Duke of Mandas, Grandee of Spain and Judith Bruce. De la Huerta was born with recurrent cystic hygroma under her arm, which she has had treated with multiple surgeries. Her mother worked as an authority on birth control and women's issues in Third World countries.


title: Paz de la Huerta

text: She attended private Saint Ann's School in the New York City borough of Brooklyn, with fellow student and future fashion designer, Zac Posen, for whom she has since modeled. She also attended the performing arts camp Buck's Rock. De la Huerta spent summers with her father in Spain while attending high school.


title: Paz de la Huerta

text: De la Huerta began modeling in her adolescence and became a runway model before transitioning into film. She made her film debut with a small role in the 1998 romantic comedy "The Object of My Affection", and the next year appeared opposite Michael Caine and Charlize Theron in "The Cider House Rules". In 2002, she appeared opposite Shane West and Mandy Moore in "A Walk to Remember", an American coming-of-age romantic drama film based on the Nicholas Sparks novel.


title: Paz de la Huerta

text: In 2007, de la Huerta was cast in the role of Linda for the film "Enter the Void", a psychedelic melodrama set in neon-lit nightclub environments of Tokyo. Director Gaspar Noé found her after holding auditions in New York City. "I met Paz and I really liked her. She had the profile for the character because she likes screaming, crying, showing herself naked—all the qualities for it."


title: Paz de la Huerta

text: In 2009, de la Huerta was cast in the HBO pilot "Boardwalk Empire", set in Atlantic City during the Prohibition era, as Enoch "Nucky" Thompson's mistress, a former Ziegfeld Follies dancer.


title: Paz de la Huerta

text: "Boardwalk Empire" was renewed for a second season, with de la Huerta returning as Lucy. Discussing the second season she said; "The first season was very different from the second season. With the first season, nobody really knew how the show was going to be received. With the second season, we had gotten lots of accolades and great reviews, so it was work, work, work, where we were shooting two episodes at a time."


title: Paz de la Huerta

text: After the second season ended, de la Huerta and fellow co-stars Michael Pitt, Aleksa Palladino, and Dabney Coleman all departed the cast. In 2012, she commented on her departure from the series, stating she wanted to put her focus on other things.


title: Paz de la Huerta

text: In 2013, she commented on how she would like to return to the hit series. "I’m still close with the producers. Terry (Terence Winter) always says it's possible for me to come back." Also adding; "I would love to come back with Lucy as a loving, doting mother."


title: Paz de la Huerta

text: In 2011, Lana Del Rey, an American singer, received widespread attention when the music video for her single "Video Games" became a viral internet sensation. The video—directed and edited by Del Rey—included paparazzi footage of de la Huerta falling down while intoxicated. When asked if she was upset about the video, de la Huerta stated, "No, no. I don't get hung up about anything really. That's insignificant. I didn't really care."


title: Paz de la Huerta

text: In April 2011, she was sued by MTV reality show actress Samantha Swetra after an altercation at a bar. De la Huerta was arrested, issued a desk appearance ticket, and released. In July 2011, she pleaded guilty to harassment and, in exchange, misdemeanor charges against her were reduced to a non-criminal violation. A judge ordered her to complete 12 weeks of alcohol counseling, one day of community service, and to stay away from Swetra.


title: Paz de la Huerta

text: In July 2011, de la Huerta signed on to play Abby Russell, the protagonist in the horror film "Nurse 3D". A sequel for "Nurse" had been rumored by de la Huerta on her Twitter page with her stating that "Nurse 2" would start shooting soon. However, In 2015, it was reported that de la Huerta was suing the filmmakers, for ruining her career and injuring her when a speeding ambulance driven by a stunt driver struck her while shooting.


title: Paz de la Huerta

text: In 2014, she completed filming in Las Vegas for the movie "Death in the Desert", cast as Margo and co-starring with Michael Madsen and Shayla Beesley. She also had a supporting role in the Canadian horror film "The Editor". She later appeared in Louis Theroux's 2015 documentary "My Scientology Movie" when she "crashed" an interview.


title: Paz de la Huerta

text: The next year, de la Huerta played Pepper in the drama film "Bare", opposite Dianna Agron. The film follows a young woman living in a small desert town in Nevada, who becomes romantically involved with a female drifter who leads her into a life of drugs, stripping, and psychedelic spiritual experiences.


title: Paz de la Huerta

text: Director Natalia Leite wanted to cast two women who were willing to be totally raw and exposed on camera in the leading roles. She stated: "I wanted to find two women who were very different from each other to put those two contrasting energies together." The film had a world premiere at the Tribeca Film Festival on April 19, 2015. Frank Scheck of "The Hollywood Reporter" wrote that de la Huerta was perfectly cast for her role as Pepper, though the film has a "mundane storyline." John Stewart of The Slanted wrote, "The film is an wonderful departure for Glee’s Dianna Agron and her performance with Paz de la Huerta is sure to spark a lot more work in the future for both rising stars."


title: Paz de la Huerta

text: De la Huerta, at the height of the Me Too movement, said in an interview with "Vanity Fair" that movie mogul Harvey Weinstein raped her on two occasions in 2010, once after demanding to enter her apartment and have a drink, and once showing up after she had been subjected to repeated phone calls and had been drinking. De la Huerta came forward to police in 2017, within the New York state statute of limitations for rape in the first degree, and the New York District Attorney's Office was considering bringing charges against Weinstein. While charges have yet to be filed in de la Huerta's case, Weinstein has been charged in New York with the rape of another woman. More than 75 women have accused Weinstein of sexual abuse; he has denied all allegations.


title: Paz de la Huerta

text: In November 2018, de la Huerta filed a $60 million lawsuit in Los Angeles Superior Court accusing Weinstein of raping her in 2010 and then embarking on a campaign of harassment that she contends damaged her career.


title: Paz de la Huerta

text: De la Huerta lived in New York City in an apartment on Gay Street, and then moved into an apartment adjacent to her mother in the Tribeca neighborhood. She has a cobra tattooed on one leg and a crown on an arm, the latter as a tribute to her lineage.


title: Tiffany Young

text: Stephanie Young Hwang (born August 1, 1989), known professionally as Tiffany or Tiffany Young, is an American singer-songwriter. Born and raised in California, she was discovered by South Korean entertainment agency SM Entertainment at the age of fifteen and subsequently moved to South Korea. After two years of training, Young debuted as a member of girl group Girls' Generation (and later its subgroup Girls' Generation-TTS) in August 2007, which went on to become one of the best-selling artists in South Korea and one of South Korea's most popular girl groups worldwide.


title: Tiffany Young

text: In 2016, Young became the second Girls' Generation member to debut as a soloist with the release of her first extended play "I Just Wanna Dance". Although Young remains a member of Girls' Generation, she left SM Entertainment in October 2017. She is currently based in Los Angeles for her solo career. She joined Paradigm Talent Agency and signed with record label Transparent Arts prior to the release of her 2019 extended play "Lips on Lips".


title: Tiffany Young

text: Tiffany Young was born Stephanie Young Hwang on August 1, 1989, in San Francisco, California. Her family consists of her father, an older sister, and an older brother. Her mother died when she was 12 years old, and she is estranged from her father. She grew up in Diamond Bar, California, and was inspired by K-pop artist BoA. Encouraged by her brother, at the age of 15, Young participated in a singing contest. She was spotted by a local SM Entertainment representative, auditioned, and was accepted as a trainee. She moved to South Korea three weeks later.


title: Tiffany Young

text: Young attended Korea Kent Foreign School and was trained at SM Entertainment for almost four years. She officially debuted as a member of South Korean girl group Girls' Generation in August 2007. The singer adopted the stage name Tiffany, the name her mother initially wanted to name her at birth. Besides Girls' Generation, Young‘s early solo work mostly involved songs recorded for side projects and original soundtracks. Throughout her career, she also participated as the host for several television programs. In early 2008, Young was diagnosed with vocal nodules and had to receive medical treatment. The symptoms relapsed in 2009 and 2010 in which the singer had to take a short break from her activities. Young acknowledged her voice became "huskier" and "more mature" as a result.


title: Tiffany Young

text: In December 2011–January 2012, Young debuted as a musical actress through a lead role in the Korean adaptation of musical "Fame". She played the character Carmen Diaz, a performing arts student who "hopes to rise to stardom by working tirelessly on her craft". In April 2012, a Girls' Generation subgroup named TTS was formed with Young and fellow members Taeyeon and Seohyun. Their debut EP, "Twinkle", debuted at number one on the Gaon Album Chart and went on to become the eighth highest selling album of the year in South Korea with over 140,000 copies sold. The subgroup went on to release two more EPs: "Holler" (2014) and "Dear Santa" (2015). In November 2013, Young participated as a contestant in the SBS' reality program "Fashion King Korea" – a program where South Korean celebrities team up with the nation's top designers to compete in fashion challenges and missions. The singer was paired with designer Ji Il-geun and finished the program in third place.


title: Tiffany Young

text: During the summer of 2015, Young began work on a solo record, with the mentality of it being the "transition into the next chapter of [her] music career." She participated in writing music since 2014, calling it "nerve-wrecking [sic] to put out music [she's] written on [her] own." Young named Girls' Generation's Taeyeon as "a big part" that helped her throughout the preparation process for the album. The two singers have been known to be best friends since Young‘s arrival in South Korea in 2004. The album, titled "I Just Wanna Dance", was released in May 2016, making Young the second Girls' Generation member to have a solo debut. Her album met with mixed but generally favorable reviews. "Billboard"s Tamar Herman called the album an "audible canvas to paint a new image for [Young]", elaborating that it "showcases [her] range as an artist." The album, having a more American influence than typical K-pop, debuted at number three on both the "Billboard" World Albums Chart and South Korea's Gaon Album Chart. It sold 61,409 physical copies and was chosen by "Billboard" as the seventh best K-pop album of 2016. The lead single, and title track, "I Just Wanna Dance" debuted at number 10 on both the "Billboard" World Digital Songs Chart and the Gaon Digital Chart. In June 2016, the follow-up single "Heartbreak Hotel", featuring Simon Dominic, was released through SM Station digital music platform. To accompany her solo releases, Young held a series of small concerts titled "Weekend" during the same month.


title: Tiffany Young

text: In August 2016 during the SMTown Live concert in Tokyo, Young posted photos that involved use of the Japanese flag and Rising Sun Flag imagery to indicate her whereabouts on her social media accounts to interact with fans. Though there was no evidence of ill-intentions, this caused heavy criticism from the Korean public as the timing coincided with Korean Liberation Day, stirring a historical war wound sentiment. This event caused her to step down from "Sister's Slam Dunk", a KBS2 variety show that she participated in at that time. Young expressed regret for her actions in two handwritten apologies posted to her social media accounts, acknowledging her lack of history knowledge. After the controversial blunder, some media spoke out in defense of Young, while others questioned the misogyny within Korean society, arguing that it can be "unforgiving" towards a female artist while a male counterpart would not receive the same treatment if the same event had occurred.


title: Tiffany Young

text: In October 2016, Young featured on the Far East Movement single "Don't Speak" for their "Identity" album. In an interview with "Billboard", the hip-hop group said that working with Young "really opened our eyes", commenting on "how versatile her range is as a singer."


title: Tiffany Young

text: Young left SM Entertainment in October 2017 and her future activities with Girls' Generation remain in discussion. She moved back to Los Angeles to study acting and pursue a solo singing career.


title: Tiffany Young

text: On March 14, 2018, Young released a cover of "Remember Me," the theme song of the Pixar film "Coco", as a single under the stage name Tiffany Young. In June 2018, it was announced that she would be debuting in the United States under Paradigm Talent Agency. She signed with Transparent Arts as her new record label, with "Over My Skin" as her first U.S. solo single.


title: Tiffany Young

text: Young collaborated with and was made the face for H&M's Autumn 2018 campaign. To coincide with their Divided Music fall campaign, Young released her second U.S. single, "Teach You", which was released on September 28, 2018. In October 2018, Young was the first female K-pop artist to walk the red carpet of the American Music Awards. She released a holiday single, "Peppermint", on November 30, 2018.


title: Tiffany Young

text: On January 9, 2019, Young announced her next single, "Born Again," which would be released on January 24 as the lead single of her next EP, entitled "Lips on Lips"; the single was moved one day later, on January 25, with Fernando Garibay confirmed as the song's producer. The music video of "Born Again" was released alongside the single on January 25. The EP's title track was released as the second single on February 14. "Lips on Lips" was released on February 22 and featured songwriting collaborations with artists such as Babyface.


title: Tiffany Young

text: "Lips on Lips" debuted at number nine on "Billboard"'s Heatseekers Albums chart and number thirty on the Independent Albums chart, with 1,000 copies downloaded and 380,000 on-demand audio streams. The EP also peaked at number eight at the Gaon Album Chart, and was certified Platinum in South Korea a week after its release. She promoted the EP through her Lips on Lips Mini Showcase Tour, which spanned eight dates around North America in March 2019. She won Best Solo Breakout at the 2019 iHeartRadio Music Awards, which aired on March 14, 2019.


title: Tiffany Young

text: Young released a new single, "Magnetic Moon", on August 2, coinciding with her Open Hearts Eve concert in Seoul on the next day, as well as another concert in Bangkok on August 17. Subsequently, she embarked on the Magnetic Moon Tour from October to November 2019, which covered eighteen tour stops in North America.


title: Tiffany Young

text: On February 16, 2021, Young was cast as Roxie Hart in the South-Korean production of the Broadway musical "Chicago". To win the role, Young participated in an open audition from which only 22 actors were selected from over a thousand applicants. Young stated that she dreamed of being a musical actress and that Roxie is one of the top three roles she wanted to play.


title: Tiffany Young

text: On June 29, 2021, it was announced that Young would be making her acting debut as supporting role in upcoming JTBC's "Reborn Rich" television series.


title: Tiffany Young

text: Tiffany is an open supporter of the LGBT community. In 2018, she wrote a love letter to the LGBTQ community for Gay Pride Month, stating that she is inspired by the themes the community and that the yearly Pride March "speaks truth on how this world can grow to be a better place". During Pride Month 2021, Tiffany joined Seoul-based LGBT collective Neon Milk along with other queer entertainers to dance to Girls' Generation's 2007 song "Into the New World", now a protest anthem in South Korea. Neon Milk have used the song as their anthem every year for Pride. She later reaffirmed her support for the community on the televised newscast JTBC Newsroom.


title: Metal Gear Solid 3: Snake Eater

text: Metal Gear Solid 3: Snake Eater is a 2004 stealth game developed by Konami Computer Entertainment Japan and published by Konami. It was released in late 2004 in North America and Japan, then in early 2005 in Europe and Australia, originally for the PlayStation 2. It was the fifth "Metal Gear" game written and directed by Hideo Kojima and serves as a prequel to the entire "Metal Gear" series. An expanded edition, titled Metal Gear Solid 3: Subsistence, was released in Japan in late 2005, then in North America, Europe and Australia in 2006. A remastered version of the game was later included in the "Metal Gear Solid HD Collection" for the PlayStation 3, PlayStation Vita and Xbox 360, while a reworked version, titled Metal Gear Solid: Snake Eater 3D, was released for the Nintendo 3DS in 2012.


title: Metal Gear Solid 3: Snake Eater

text: Set in 1964, 31 years before the events of the original "Metal Gear", the story centers on the FOX operative codenamed Naked Snake as he attempts to rescue Russian rocket scientist Nikolai Stepanovich Sokolov, sabotage an experimental superweapon, and assassinate his defected former boss. While previous games were set in a primarily urban environment, "Snake Eater" adopts a 1960s Soviet jungle setting, with the high tech, near-future trappings of previous "Metal Gear Solid" games replaced with wilderness. While the environment has changed, the game's focus remains on stealth and infiltration, while retaining the series' self-referential, fourth-wall-breaking sense of humor. The story of "Snake Eater" is told through numerous cutscenes and radio conversations.


title: Metal Gear Solid 3: Snake Eater

text: Considered one of the greatest video games of all time, "Metal Gear Solid 3" was met with critical acclaim and was a commercial success, having sold more than four million copies worldwide .