Circuit for clamping bridge over-voltages in a voltage-fed quasi Z-source converter

Unlike the voltage source converter, the Z-source converter can boost as well as buck the input voltage. However, the presence of physically large components in the impedance network introduces large parasitic inductances into power device commutation paths. This leads to consequent overvoltages at power device turn-off. A simple circuit for addressing this is presented. Practical results are given for a voltage-fed quasi- Z-source inverter with discontinuous input current

High-Efficiency NPC Multilevel Converter Using Super-Junction MOSFETs

Super-junction MOSFETs exhibit low on-state resistances and low switching losses. However, the reverse recovery behavior of their intrinsic diodes and their output capacitance characteristics make their deployment in freewheeling locations challenging. In this paper, a new snubber circuit arrangement has been proposed for a three-level converter to minimize the effect of the output capacitance. This is used in conjunction with diode deactivation circuitry to address the diode recovery behavior. Results are given for a three-phase three-level neutral point clamped converter running from an input voltage of 720 V and supplying a 3-kVA load. The converter operates with no forced cooling and efficiency is estimated at 99.3%. Apart from lower energy consumption, an advantage of high efficiency is a reduced converter mass due to reduced cooling requirements

A national multiple baseline cohort study of mental health conditions in early adolescence and subsequent educational outcomes in New Zealand

Young people experiencing mental health conditions are vulnerable to poorer educational outcomes for many reasons, including: social exclusion, stigma, and limited in-school support. Using a near-complete New Zealand population administrative database, this prospective cohort study aimed to quantify differences in educational attainment (at ages 15-16 years) and school suspensions (over ages 13-16 years), between those with and without a prior mental health condition. The data included five student cohorts, each starting secondary school from 2013 to 2017 respectively (N=272,901). Both internalising and externalising mental health conditions were examined. Overall, 6.8% had a mental health condition. Using adjusted modified Poisson regression analyses, those with prior mental health conditions exhibited lower rates of attainment (IRR=0.87, 95% CI 0.86-0.88) and higher rates of school suspensions (IRR=1.63, 95% CI 1.57-1.70) by age 15-16 years. Associations were stronger among those exhibiting behavioural conditions, compared to emotional conditions, in line with previous literature. These findings highlight the importance of support for young people experiencing mental health conditions at this crucial juncture in their educational pathway. While mental health conditions increase the likelihood of poorer educational outcomes, deleterious outcomes were not a necessary sequalae. In this study, most participants with mental health conditions had successful educational outcomes

A nod in the wrong direction : Does nonverbal feedback affect eyewitness confidence in interviews?

Eyewitnesses can be influenced by an interviewer's behaviour and report information with inflated confidence as a result. Previous research has shown that positive feedback administered verbally can affect the confidence attributed to testimony, but the effect of non-verbal influence in interviews has been given little attention. This study investigated whether positive or negative non-verbal feedback could affect the confidence witnesses attribute to their responses. Participants witnessed staged CCTV footage of a crime scene and answered 20 questions in a structured interview, during which they were given either positive feedback (a head nod), negative feedback (a head shake) or no feedback. Those presented with positive non-verbal feedback reported inflated confidence compared with those presented with negative non-verbal feedback regardless of accuracy, and this effect was most apparent when participants reported awareness of the feedback. These results provide further insight into the effects of interviewer behaviour in investigative interviewsPeer reviewedFinal Accepted Versio

Potential of Water and Salt Yields From Surface Runoff on Public Lands in the Price River Basin

The report examines possible sources of dissolved salts in the Price River basin. Ephemeral and intermittent streams contributed dissolved salts and are the focus of the study. Seven subwatersheds and the Price River at Heiner are investigated to examine the effects of existing watershed characteristics on runoff and dissolved salts production. Alternatley, the report examines the effects of specific land treatments on surface runoff quantity and quality. Various instrumentation techniques are evalauted to help improve future data collected capabilities in intermittent channels. The examination of the data reveals various trends that might be considered for further investigation in subsequent studies

Grazing Management of Tagasaste (Chamaecytisus Proliferus) for Sheep and Cattle Production in Southern Australia

Direct grazing of hedgerows of tagasaste (Chamaecytisus proliferus) by sheep or cattle appear to be very robust systems. Tagasaste persists under a continuous grazing regime with cattle such that plant regrowth maintained between 5 and 10 cm in length produces in excess of 215 kg of animal liveweight/ha/year. This level of production is also sustained within a rotational grazing regime. Under both grazing systems cattle production within a year is highly seasonal, with liveweight gains from young cattle peaking at 1.0-1.5 kg/head/day in winter and spring, but dropping to maintenance only by late summer-autumn. Sheep, like cattle, can be grazed on tagasaste at any time of the year, however their different grazing habits demand sheep be used in an intensive, short-term grazing system for approximately 30 days at a time on any one stand of tagasaste

Performance of an Evaporative Cooling System in a Gestation House

This field study was conducted to determine the effectiveness of an evaporative pad cooler for modifying the environment in a gestation house in Kentucky and to compare the measured results with the calculated performance of evaporative cooling systems. The building used in the study was a 68-crate gestation house, as described in Figure 1. The building was oriented east-west and was well insulated. There were no windows in the facility. It was fully occupied, throughout the study, with sows with an average weight of 350 lbs. A negative pressure system was used to ventilate the building with a 36 single-speed exhaust fan located in the east end wall (Figure 1). A 4\u27 x 12\u27 evaporative pad was located in the west end wall adjacent to the air intake. Shutters were mounted on the outside of the building to provide shade for the pads and to protect them during inclement weather

The heterogeneous OH oxidation of palmitic acid in single component and internally mixed aerosol particles: vaporization, secondary chemistry, and the role of particle phase

International audienceWe studied the OH oxidation of submicron aerosol particles consisting of pure palmitic acid (PA) or thin (near monolayer) coatings of PA on aqueous and effloresced inorganic salt particles. Experiments were performed as a function of particle size and OH exposure using a continuous-flow photochemical reaction chamber coupled to a chemical ionization mass spectrometer (CIMS) system, for detection of gas and particle-bound organics, and a DMA/CPC for monitoring particle size distributions. The loss rate of PA observed for pure PA aerosols and PA on crystalline NaCl aerosols indicates that the OH oxidation of PA at the gas-aerosol interface is efficient. The pure PA oxidation data are well represented by a model consisting of four main processes: 1) surface-only reactions between OH and palmitic acid, 2) secondary reactions between palmitic acid and OH oxidation products, 3) volatilization of condensed-phase mass, and 4) a surface renewal process. Using this model we infer a value of ?OH between 0.8 and 1. The oxidation of palmitic acid in thin film coatings of salt particles is also efficient, though the inferred ?OH is lower, ranging from ~0.3 (+0.1/?0.05) for coatings on solid NaCl and ~0.05 (±0.01) on aqueous NaCl particles. These results, together with simultaneous data on particle size change and volatilized oxidation products, provide support for the ideas that oxidative aging of aliphatic organic aerosol is a source of small oxidized volatile organic compounds (OVOCs), and that OH oxidation may initiate secondary condensed-phase reactions