Optimal work-rest schedules under prolonged vibration.
This research was conducted for the purpose of studying the performance and recovery characteristics of men when subjected to low-level, whole-body vertical sinusoidal vibration for durations of one to two hours. Several male subjects performed a vertical compensatory tracking task using a CKT display according to three work-rest schedules under both normal and vibratory environments. The vibratory environment was that of vertical sinusoidal vibration with a frequency of.5 cps and an amplitude- of 0-08 inches resulting in an acceleration intensity of approximately 0.20 g. The working period was divided into equal intervals during which performance was continuously monitored. Decrement of performance was measured using absolute error score. Results and conclusions are presented regarding performance decrement and recovery under varying work-rest schedules. Optimum work-rest schedules and implications of control tasks under a vibratory environment are discussed.
Beurteilung der Beanspruchung des Menschen bei unterbrochener Schwingungsexposition
SummaryThe psychophysical reactions to stochastic vibrations transmitted in vertical direction to sitting man are investigated in simulated experiments under laboratory conditions. In the framework of an appropriate concept of assessment, indicators related to bottleneck situations in functional systems of the organism for activity and strain measurements allow the evaluation of the recreation efficiency of interruptions in exposure time. The special meaning of the distribution and thus the frequency rate of the interruptions can be illustrated particularly by the variance in time of the strain processes of selected muscles. Between the degree of muscle fatique and the period of uninterrupted exposure time (expressed in “exposition-interruption-distribution”) a significant correlation results so that numerous interruptions of vibration exposure should be considered as a profitable guideline for work design with respect to ergonomics.ZusammenfassungIn Simulationsexperimenten unter Laborbedingungen werden die psychophysischen Auswirkungen vertikaler regelloser Schwingungsbelastung des sitzenden Menschen untersucht. Im Rahmen eines geeigneten Beurteilungskonzeptes gestattet die Kombination von engpa\orientiert ausgewÄhlten AktivitÄts- und Beanspruchungsme\grö\en auch die Beurteilung der Erholungswirksamkeit von Expositionszeitunterbrechungen. Insbesondere die zeitvarianten Beanspruchungsprozesse ausgewÄhlter Muskeln weisen auf die Bedeutung der Verteilung und damit der HÄufigkeit der Unterbrechungen hin. Es ergibt sich ein gesicherter Zusammenhang zwischen dem Grad der Muskelermüdung und der Dauer der ununterbrochenen Expositionszeit, ausgedrückt durch die „Expositions-Unterbrechungs-Verteilung“, so da\ hÄufige Unterbrechungen der Schwingungsexposition als ergonomisch günstige Gestaltungsma\nahmen anzusehen sind.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.