Analysis and modeling of novel brushless exciter based on hybrid excitation topology
The exciter is a key component of the synchronous generator system with self-excited initiation. Based on the topology of hybrid excitation, this paper proposes a novel brushless exciter, which is suitable for an isolated power system. The parameters of the exciter are calculated by the numerical method based on finite element model, and the state space model is established. The experimental researches are carried out on a 3 kW prototype.
A survey of the second-generation vessel integrated power system
The vessel integrated power system (IPS) is the third revolution in the naval vessel power which has evolved from wind power to steam power and then from steam power to nuclear power, marking the trend of naval vessel power. The first-generation IPS has been widely applied to engineering in many countries. However, there are some defects in it such as huge volume, heavy weight and low compatibility when the first-generation IPS is used in light ships, because its power density is limited by the properties of the electromagnetic materials, power electronics, etc. This paper has presented the concept and typical architecture of the second-generation IPS and its technical advantages, introduced several key technologies concerning the second-generation IPS that need a breakthrough according to the current technical level, and pointed out direction of the research and engineering application of the second-generation IPS.
Daily weather variables and affective disorder admissions to psychiatric hospitals
Numerous studies have reported that admission rates in patients with affective disorders are subject to seasonal variation. Notwithstanding, there has been limited evaluation of the degree to which changeable daily meteorological patterns influence affective disorder admission rates. A handful of small studies have alluded to a potential link between psychiatric admission rates and meteorological variables such as environmental temperature (heat waves in particular), wind direction and sunshine. We used the Kruskal-Wallis test, ARIMA and time-series regression analyses to examine whether daily meteorological variables—namely wind speed and direction, barometric pressure, rainfall, hours of sunshine, sunlight radiation and temperature—influence admission rates for mania and depression across 12 regions in Ireland over a 31-year period. Although we found some very weak but interesting trends for barometric pressure in relation to mania admissions, daily meteorological patterns did not appear to affect hospital admissions overall for mania or depression. Our results do not support the small number of papers to date that suggest a link between daily meteorological variables and affective disorder admissions. Further study is needed.