Study on Transformer Magnetic Biasing Control Method for AC Power Supplies

This paper presents a novel transformer magnetic biasing control method for high-power high-performance AC power supplies. Serious consequences due to magnetic biasing and several methods to overcome magnetic biasing are first discussed. The causes of the transformer magnetic biasing are then analyzed in detail. The proposed method is based on a high-pass filter inserted in the forward path and the feedforward control. Without testing magnetic biasing of transformer, this method can eliminate magnetic biasing of transformer completely in real-time waveform feedback control systems though the zero error of the Hall effect sensors varies with time and temperature. The method has already been employed in a 90KVA AC power supply. It is shown that it offers improved performance over existing ones. In this method, no sensors are used such that the zero error of the Hall effect sensors has not any influence on the system. It is simple to design and implement. Furthermore, the method is suitable for various power applications.

Emergency management of nursing human resources and supplies to respond to coronavirus disease 2019 epidemic

Objective:To introduce the emergency management of nursing human resources and supplies of a large general hospital when facing the outbreak of coronavirus disease 2019(COVID-19).Method:The Nursing Department of the hospital fully executed its functional authority to establish a three-level echelon of sustainable support,allocate human recourses dynamically,organize pre-service training,supervise the key working steps,formulate positive incentive methods,and deploy medical supplies scientifically.Result:By taking these strategies,the hospital effectively improved the coping capacity of the nursing team and played a positive role in the prevention and treatment of COVID-19.Conclusion:The emergency management of nursing human resources and material resources for COVID-19 of the hospital is successful.But several deficiencies were identified as well,which indicated that the hospital needs to establish an efficient emergency management system,and pay attention to the practice of nursing emergency plans to enhance coping capacities in public health emergencies.

Reducing the minimum output power of soft-switching inverter arc welding power supplies

The full-bridge zero-voltage and zero-current switching inverter, which can adjust the output power by keeping the duty-cycle of lagging arm constant, changing the duty-cycle of leading arm, is a common circuit topology of soft-switching inverter arc welding power supplies. However, the output power still remains a certain value when the duty-cycle of leading arm decreases to zero. The working-mode of soft-switching inverter and the waveforms of major parameters with the condition of duty-cycle of leading arm being zero are studied in this paper. U-1 characteristic experiments prove that the minimum output power of soft-switching circuit, which depends on the charged voltage of capacitors in parallel with leading arm, can be decreased by reducing the duty-cycle of lagging arm. By switching working-modes between half-bridge and full-bridge, the output power can swing from zero to the power rating.

Applications of Green Design in Office Supplies

Humans' immoderate exploit of natural resources causes a crisis to their own living environment. Besides the hazards from industry and agriculture production process, a large of garbage produced in people's daily work also destroy the ecological environment. Everyday office supplies consume considerably increasing resources. Green design indicates people's reflection on the worse environment and ecology inflicted by modern technological culture. Therefore, applying green design to office supplies, big resources consumers, has a profound and practical meaning in improving our living environment.

Effects of O_(2) addition on the plasma uniformity and reactivity of Ar DBD excited by ns pulsed and AC power supplies

Dielectric barrier discharges(DBDs)have been widely used in ozone synthesis,materials surface treatment,and plasma medicine for their advantages of uniform discharge and high plasmachemical reactivity.To improve the reactivity of DBDs,in this work,the O_(2) is added into Ar nanosecond(ns)pulsed and AC DBDs.The uniformity and discharge characteristics of Ar ns pulsed and AC DBDs with different O_(2) contents are investigated with optical and electrical diagnosis methods.The DBD uniformity is quantitatively analyzed by gray value standard deviation method.The electrical parameters are extracted from voltage and current waveforms separation to characterize the discharge processes and calculate electron density n_(e).The optical emission spectroscopy is measured to show the plasma reactivity and calculate the trend of electron temperature T_(e) with the ratio of two emission lines.It is found that the ns pulsed DBD has a much better uniformity than AC DBD for the fast rising and falling time.With the addition of O_(2),the uniformity of ns pulsed DBD gets worse for the space electric field distortion by O_(2)^(-),which promotes the filamentary formation.While,in AC DBD,the added O_(2) can reduce the intensity of filaments,which enhances the discharge uniformity.The ns pulsed DBD has a much higher instantaneous power and energy efficiency than AC DBD.The ratio of Ar emission intensities indicates that the T_(e) drops quickly with the addition of O_(2) both ns pulsed and AC DBDs and the ns pulsed DBD has an obvious higher T_(e) and n_(e) than AC DBD.The results are helpful for the realization of the reactive and uniform low temperature plasma sources.

Analysis and design of over-current limit control strategies applied in aeronautical power supplies

Some Over-Current Limit Control strategies are analyzed and designed to meet the demands of high reliability and rapid dynamic response in the aeronautical power supply applications. The control schemes are both effective in DC-DC converters and DC-AC converters. Controller models are set up, and the over-current limit operation principles of analogy and digital control are analyzed too. An 800VA aeronautical power supply bas been constructed to verify the performance of the proposed control strategy in various cases such as the sudden load change and the constant load. The analysis and experiments confirm the advantages of the proposed over-current limit strategies as follows： simple,effective and reliable.

Design method for transistor-inverted welding power supplies

From the viewpoint of reliability and practicability, a general design method and the related considerationsfor transistor- inverted welding power supplies are proposed in this paper. The detail contents are composed of the choice ofinverters, the choice and protection of transistors, the determination of inverting frequency, the design of transformers,and the choice of output rectifiers and rectifying diodes. Besides, a concrete design example of the transistor-invertedpower supply for plasma arc cutting is introduced.

Overview of Circuit Topologies for Inductive Pulsed Power Supplies

The pulsed power supply(PPS)is one important component in the electromagnetic launch system.The inductive PPSs have attracted researchers’attentions with the major advantages of high energy storage density(over the capacitive PPSs)as well as simple structure and easy control(over the rotating mechanical PPSs).As for the inductive PPSs,the circuit topology of the basic module will directly determine the comprehensive performance of the whole system.From the perspectives of working principles,strengths,weaknesses,and comprehensive performance,this paper presents a historical and technical review of the major circuit topologies for the inductive PPSs.

Strategies for Improving Gas Supplies for Sustainable Power Generation in Ghana

Technologies for gas conversion have attracted more serious attention, but energy efficiency, supply deficiencies, as well as other risks undermining the gas supply industry, make it difficult to achieve sustainability in gas supply in Ghana. This study explored strategies for improving supplies for sustainable power generation in Ghana. Specifically, the study investigates the risks associated with the gas supply industry and also investigates strategies for improving gas supplies in Ghana. A descriptive study that applied both qualitative and quantitative tools was applied to data collection and analysis to allow for an in-depth analysis of the findings of the research. The population was concentrated on the regulators (Energy Commission) and consumers (VRA and Sunon Asogli, and GNGC/Eni in the supply domains. In all, 357 population was targeted with a sample of 151. Probability (simple random sampling) and non-probability (purposive) sampling approaches were applied to source participants for the study. Statistical inferential tools that guided the analysis included means, standard deviation, Relative Importance Index (RII). The study identified issues of power sector debt due to the weak financial background of the gas supply sector, poor infrastructure, issues of corruption created by delays, poor transparency and weak regulatory framework as key risk factors in the gas supply industry in Ghana. The study also concluded that strategies to support the drive to achieve sustainability in the gas supply industry should involve a planned action towards providing regular and improved infrastructure in transportation and gas supply pipelines to enhance the visibility of the local gas industry and to also meet both domestic and industrial demand for gas products. Again, there should be the establishment and maintenance of functional gas-related policies and regulators, as well as an emergency supply plan to address any shocks that may tend to impact the gas supply industry in Ghana.

Roles and contributions of developing country vaccine manufacturers to global vaccine supplies

Developing Country Vaccine Industry represented by Developing Country Vaccine Manufacturer Network has a track record of manufacturing high quality vaccines.The timely and consistently supplies by DCVMN has led to significant progress in expanding the coverage of vaccine globally,resulting in the prevention of more than 2 million death annually.The contributions of industry to polio eradication,meningitis epidemic,pandemic influenza,MMR vaccination and DPTbased combination vaccines have created a significant impact on global health indicators[1].

Air-Water Cooling System for Switch-Mode Power Supplies

The results are presented of an experimental investigation of heat transfer in an air-liquid cooling system for a Switch-Mode Power Supply (SMPS) for TV digital power amplifiers. Since these SMPSs are characterized by high power and high compactness, thereby making the standard cooling techniques difficult to be used, a new cooling system is developed, using water and air as the cooling media. The active components (MOSFETs) are cooled with a liquid cold-plate, the passive ones (condensers, transformers, coils) with an air flow, in turn cooled by the cold-plate. By inserting the cooling system in an experimental tool where it is possible to control the cooling water, measurements are made of temperature in the significant points of the SMPS. The electric efficiency is also measured. The evaluation of the thermal performance of this cooling system is useful in order to limit its maximum operational temperature. The efficacy of the cooling system is demonstrated;the trends of efficiency and power dissipation are evidenced.

Farm produce prices rise on reduced supplies

Xinhua reported on March 20 that prices of major farm produce monitored by the government rose as snow falls interrupted supplies,the Ministry of Commerce said.The wholesale prices of 18 staple vegetables rose 3.2 percent from one week earlier,and the prices have increased 9.

Design of a System for Auto-patrolling Power Supplies and Displaying Beam Status In HIRFL

A practical application for patrolling the device’s status and displalying beam status of HIRFL has been described.With regard to the kinds of the controlled devices,the system consists of two parts:First,the alarm system is applied to monitor all power supplies,which are decomposed into six groups in accordance with their positions for the convenience of user’s operation.The amount of magnet lens and power supplies of

CSR Pulsed Switching Power Supplies

In 2001, CSR power supply system made a great progress. Three prototypes were designed for CSR quadruple and correct magnet. Three different companies provided the three prototypes, but the same circuit-chopper were employed. The simplified diagram is showed in Fig.1. All pulsed switching power supply prototypes were tested successfully before the end of 2001.

ZTE Supplies Comprehensive Range of Communications Solutions for Beijing 2008 Olympic Games

ZTE Corporation,a leading global provider of telecommunications equipment and network solutions,supplied a comprehensive range of

Spatio-temporal evolution of the coordinated development of high-tech industry agglomeration and resource-environmental carrying capacity in the Yellow River Basin

Under the background of new infrastructure,the Yellow River Basin’s superior growth cannot be separated originating with the synergistic effect of scientific and technological inventiveness and ecological civilization construction.In light of the coupling coordination analysis of the coordination effect of provincial high-tech industry agglomeration and resource carrying capacity in the Yellow River Basin from 2009 to 2021,The evolution of the geographical and temporal pattern of development was investigated using the Moran index and kernel density estimation.The results show that the agglomeration of high-tech industries in the Yellow River Basin presents a development trend of seek improvement in stability,and there is a good coupling and coordination throughout the progression of scientific and technological innovation and the loading capacity of the resource,from the viewpoint of a time series.From the perspective of spatial pattern distribution,the whole basin aims at the lower reaches,accelerates the optimization of digital industry and promotes Yellow River Basin development of superior quality through innovation support and increase of input,and based on policy guidance.

Sustainable reputation of lithium-ion battery supplier and its impact on transaction equilibrium in the electric vehicle supply chain

In the lithium-ion battery(LIB)supply-chain,transactions involve several rounds of ordering,production and delivery between LIB suppliers and electric vehicle(EV)manufacturers.The sustainable performance of LIB suppliers,related to various characteristics,significantly affects the participants’sustainable reputations.The EV-LIB supply-chain transaction mechanism is explored from the perspective of the exchange economy comprehensively addressing both short-term economic profit and long-term sustainable reputation.Specifically,a“profit-reputation”utility function is proposed to reflect participants’expectations regarding cooperation profit and sustainable reputation.Additionally,an Edgeworth box model is developed to describe the participant’s balance determinations as a contract curve,revealing the Pareto conditions for mutually beneficial transactions based on sustainable performance.Furthermore,several principal-agent models are established to analyze the equilibrium of sustainable transactions within the EV-LIB supply-chain under varying dominance scenarios.A case study of an EV-LIB transaction is conducted to demonstrate the feasibility and effectiveness.This study aims to assist supply chain managers,researchers and decision-makers in exploring the role of participant’s sustainable reputation and its influence on supply-chain transaction and equilibrium,particularly in the context of designing cooperative contracts and negotiation process to foster sustainable supply chains.

Strategic equilibrium price analysis and numerical simulation of preponderant high-tech metal mineral resources

Based on exploitation compensation value system of preponderant high-tech metal mineral resources and distortion of pricing mechanism, social utility function was constructed to modify decision utility function of developers, and was extended to Stackelberg production decision model of preponderant high-tech metal mineral resources development. Analyzing the influences on market monopoly, output and price decision-making exerted by altruistic preferences, inequity aversion and sequential reciprocity fairness belief equilibrium, game fairness equilibrium which is significant in experimental economics can be obtained and verified by numerical simulation. In process of strategic pricing, method that uses the variation of producer surplus to measure strategic value from psychological preferences was proposed for the first time and technical support to improve exploitation compensation value system of preponderant metal mineral resources was available.