Analysis of S^p_q current systems by using corrected geomagnetic coordinate

The S^p_q equivalent current system of the quiet day geomagnetic variation in the polar region is very complicated. It is composed of several currents, such as the ionospheric dynamo current and the auroral electrojet caused by the field aligned current. S p q is unsymmetrical in both polar regions. In this paper, the S p q current systems are analyzed in the corrected geomagnetic coordinates (CGM) instead of the conventional geomagnetic coordinates (GM), and the symmetries of the S p q current in different systems are compared. Then the causes of S p q asymmetry in the GM coordinates are discussed; the effects of each component in S p q are determined.

Current Situation of China's Automotive Industry Enterprises

Atpresent,thereare122completevehiclemanufacturersinChina,vehiclemanufacturersandover3000autoparts/componentsenterprises.149ofthemarejointventures.Thereare1.98millionemployeesintheindustrywith180.9billionyUanfixedassetsand123billionyuannetvalue.Atthee...

Current Situation of China's Thermal Power Generation Equipment & Its Development Perspective

1. The present manufacturing situation of China’s thermal power generation equipment By the year 1995. development of China’s electric power industry has experienced a course of a hundred years. Over a period of the initial 50 years. China’s development of electric power was slow. At the time of 1949, the total installed capacity in China was 1,850 MW and the electricity generated was only 4.3 billion kWh. During the past 46 years after 1949, her

Current Situation and the Outlook of China＇s Natural Gas Industry

Core indicators of China’s natural gas industry in 2016In 2016,China produced 132.82 bcm of natural gas and 1.61bcm of coal-to-gas,production amounts that were 1.5%and 15.8%higher than those of the previous year,respectively.The imported gas volume was 38.34bcm through pipeline(up 9.0%from the previous year)and 33.74 bcm via LNG facilities(up 30.6%from

The Current State of China's Freshwater Resources and Related Suggestions

China has many lakes, marshlands and rivers. Due to their uneven geographical distribution and varied degrees of salinity, their exploitable freshwater resources are limited. In the wake of the highspeed growth of national economy in recent years, human infringement upon their natural settings has been increasingly intense, leading to the degeneration of China's lacustrine ecosystems and the degradation of their surrounding environments. Lakes are shrinking and becoming more saline. In arid and semi-arid inland areas, some of them have even disappeared. In addition, lake water pollution and eutrophication in densely populated areas are getting worse, resulting in serious water shortages in some places. Silt deposition in lake basins, water surface shrinkage caused by hectic and irrational reclamation for farmland, the prevalence of flooding and water-logging calamities and ecosystem depletion caused by predatory exploitation of fishery resources, all of these have become restrictive factors in regional sustainable development. The author of this article suggests measures for the protection and sustainable exploitation of limnetic settings in China.

Current Situations and Problems of Logistics for Guangxi Fresh Agricultural Products in the New Period and Recommendations

In recent years,Guangxi realized consecutive bumper harvests in fresh agricultural products,leading increase of logistics demand;logistics infrastructure begins to take shape,and logistics of fresh agricultural products takes on diversified development form with wholesale market as main form. However,traditional fresh agricultural products are not selling well and it lacks construction of supply chain; the construction of logistics information system for fresh agricultural products lags behind; organizational level of production and operation of fresh agricultural products is low. Through analyzing current situations and existing problems of logistics of Guangxi fresh agricultural products in the new period( 21 st century),this paper came up with recommendations for developing logistics of fresh agricultural products of Guangxi. Government should increase policy and financial support,build and manage supply chain of fresh agricultural products,accelerate construction of logistics information system for agricultural products,and improve organizational level of logistics of fresh agricultural products,to ensure healthy development of logistics of fresh agricultural products in Guangxi.

Current Situations of Competitive Scientific Research Projects for Agri-scientific Research Institutions: A Case Study of Tropical Crops Genetic Resources Institute of Chinese Academy of Tropical Agricultural Sciences

This paper collected and arranged competitive scientific research projects undertaken by Tropical Crops Genetic Resources Institute of Chinese Academy of Tropical Agricultural Sciences in 2003-2014. Through statistical analysis on quantity of projects,funded amount,age of person responsible,professional title of person responsible,academic degree of person responsible,research object,it discussed relevant characteristics and rules. Finally,it came up with pertinent measures and recommendations,in the hope of providing services for decision-making and scientific and technological management.

基于剩余电流和不平衡电流突变向量比的TN-C-S系统漏电故障检测方法

TN-C-S系统在我国应用广泛,但由于固有剩余电流大,无法区分负荷投切和故障引起的剩余电流变化,漏电总保和中保无法投运,存在安全隐患。针对该问题,提出一种基于剩余电流和不平衡电流突变量之比的漏电故障保护方法。首先,分析剩余电流回路,剩余电流和不平衡电流突变量之比在单相接地故障发生时刻突变,在负荷投切时不变。其次,基于中性线阻抗和接地阻抗不会发生突变的特征,计算故障电流突变量幅值,以故障电流突变量幅值越限作为故障判别依据,实现漏电故障检测。仿真及试验证明,所提方法可有效区分负荷投切和漏电故障,实现大幅值固有剩余电流下的漏电故障检测,在单支路和多支路系统中的检测灵敏度分别为70、150 mA,满足TN-C-S系统多级漏电保护的灵敏度要求。

基于频率切换的S/LCL补偿恒流恒压型WPT系统研究

由于传统的插入式系统结构繁杂且频繁插拔容易发生电火花等危险,因此无线电能传输(wireless power transfer,WPT)系统凭借其固有的优势得到了广泛的研究,逐渐融入各种工业应用中.为了确保电池的性能及使用寿命,有效地为电池提供所需的恒定充电电流和恒定充电电压是非常必要的.然而在充电过程中,电池的等效电阻会发生显著变化从而导致系统很难在近似零相位角(zero phase angle,ZPA)运行下同时实现与负载无关的恒流输出和恒压输出.鉴于此,提出1种基于S/LCL补偿的WPT系统,该系统可以在2个固定频率下实现具有ZPA运行的恒流和恒压输出.最后,搭建了1台恒流充电为3 A和恒压充电为80 V的验证性实验样机,验证了所设计的WPT系统的正确性和可行性.

Analysis On the Current Status and Future Development Trend of China's Lithium Industry

Recently,the 2016 Lithium Industry Forum,an event hosted by the China Nonferrous Metals Industry Association Lithium Branch,opened in Xining,Qinghai Province.Li Bingxin,Deputy Secretary-general of the China Nonferrous Metals Industry Association Lithium Branch,shared the operation

Magnetite Quartzite-Type Iron Ores – China's Most Important Current Iron Ore Source

China is abundant in iron-ore resources, with proven ore reserves of 576.62×10^8 t and proven reserves of 210×10^8 t, containing an average iron content of 33%. However, the rich iron-ore reserves of 10.85×10^8 t only account for 1.9% of all proven reserves. China＇s iron-ore resources are characterized by many lean ores and a few rich ones.

EFFECT OF DIFFERENT WAVEFORM'S ALTERNATING CURRENT ON THE INCISION'S SENSITIVITY

Compared with the conventionally used i=iosinωt alternating current, using asymmetric triangular and pulse wave as input signals can greatly enhance the incision's sensitivity of 'dE/dt-E'oscillogram.

Investigation on 10/350 Crowbar Pulse Current Circuit

Structure of main air discharging switch and a crowbar TVS （triggered vacuum switch） are designed and their triggering characteristics are investigated. The experimental results showed that for TVS the operating voltage range is from 1.3 kV to 120 kV, its maximum delay time is 400 ns and its jitter is 4-10 ns. Based on these results the crowbar 10/350μs （i.e., with a front time of 10μs and a duration of 350 μs） pulse current circuit and its controlling circuit are designed. With a 10μF stored capacitor C and a 6 μF waveform forming induction, a pulse current is generated with a maximum of 100 kA, front time of 10 ns and duration of 350μs. This pulse waveform can be used for testing SPD （surge protective devices）.

Consistency evaluation of the current distribution of short-circuit tests in AT feeding systems for high-speed railways

To improve the accuracy of fault location system, several short-circuit tests need to be conducted before being brought into service in autotransformer （AT） feeding systems for high-speed railways in China. However, no systematic algorithm yet exists to evaluate the consistency of the current distribution of short-circuit tests. A methodology is proposed in this paper to address this problem. Based on Kirchhoff’s current law and the generalized method of symmetrical components, the current deviations of the AT feeding systems are analysed and then normalized with the short-circuit current as they vary greatly with systems and short-circuit sites. It is also found that the short-circuit current varies with the calculation methods, and its unbiased standard deviation also reflects the consistency of the short-circuit test. The mean and maximum of the current deviations, as well as the unbiased standard deviation of the short-circuit current, show the consistency of the short-circuit test from different aspects,although the last two items are highly relevant. Therefore, a unified evaluation index is defined as the sum of the three items, and then applied in two case studies to test its performance. The results show that, the proposed index canclearly distinguish the consistency of the short-circuit tests and may be used to sort the short-circuit tests for fault location systems. Besides, some short-circuit tests may have very poor consistency indices, and thus are not applicable to the tuning of fault location systems. In the authors’ opinion, the determination of the threshold of the proposed index needs further investigation.

Discussions on China's Current Economic Situation

It can be certain that the series of related policies will create a breakthrough in China’s economy.The inflation rate in China is low at present, and this is the right moment to adopta currency policy to raise directly the income of peasants and low-income families.

基于频率切换的LCC-S型IPT系统恒流/恒压输出研究

为实现感应电能传输(Inductive Power Transfer,IPT)系统在变负载条件下的恒流/恒压高效输出,提出一种基于频率切换的LCC-S型IPT系统参数配置及优化方法。从LCC-S补偿拓扑入手,分别得到系统恒流或恒压零相位角(Zero Phase Angle,ZPA)输出的条件方程,并推导了电流增益、电压增益与系统参数之间的定量关系;进一步通过定义系统的输出增益比,分析了恒流/恒压模式下输出增益、负载电阻与整体效率的关系;在此基础上,通过选取最佳的输出增益值,使得系统整体效率达到了全局最大化。仿真结果表明,负载电阻在3~300Ω的变化范围内包括恒流/恒压模式切换瞬间都能保持稳定的输出,并且恒流/恒压模式下均能实现ZPA运行,同时系统整体效率都维持在90%以上。

REALIZATION OF THE RMB'S CONVERTIBILITY UNDER THE CURRENT ACCOUNT AND ITS INFLUENCE

It was approved by the State Council in I984 to establish economicand technological development zones in 14 coastal port cities tofunction as windows for those cities to attract foreign investment,introduce advanced technology and management methods andexpand the export-oriented economy.Since 1992,18 other developmentzones have been approved by the Council,increasing the number ofsuch zones to 32.

Josephson Current in f-Wave Superconductor/f-Wave Superconductor Junctions

We study the temperature T and the phase of the Josephson critical current I(φ)by taking into account theroughness scattering effect at inerface in an f-wave superconductor(S)/Insulator layer(I)/f-wave superconductor(S)junction.It is found that the Josephson critical currents in f-wave S/f-wave S,the barrier strength and the roughnessstrength at inerface always suppress the Andreev reflection.When α=β,the phase dependence of the Josephson currentI(φ)between two f-wave S is predicted to be simφ;particularly,when α≠β,the phase dependence of the Josephsoncurrent I(φ)between two f-wave superconductors is not predicted to be sin φ and with the barrier strength increasing,the period of the I((φ)turns decrease.

基于LCC-S补偿式谐振拓扑的锂电池WPT系统研究

无线电能传输(wireless power transfer,WPT)系统具有安全、可靠、方便等优点。文章在分析WPT系统锂离子电池内阻及其典型充电方式的基础上,通过对WPT原理和谐振拓扑结构的研究,提出了基于LCC-S补偿式谐振拓扑的WPT系统。在电池等效负载变化的情况下,通过合理的参数设计,LCC-S补偿式谐振拓扑结构可以分别实现与负载无关的恒流模式和恒压模式,无需切换拓扑结构。在理论分析的基础上,设计了系统的参数,并通过MATLAB仿真系统搭建仿真模型,验证了研究中的恒流模式和恒压模式。