Measurement of mean excitation energy by energy loss

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发电机失磁保护阻抗元件定值整定的再讨论——对2007年版《IEEE Guide for AC Generator Protection》的斟酌

发电机失磁保护阻抗元件定值整定中,始终存在防误动和加速动作的矛盾。根据理论分析和运行实践,认为解决矛盾应从阻抗平面的R轴方向扩大阻抗动作区,即将理论上的汽轮发电机静稳边界功角90°,减小为实用的静稳边界功角55°～65°,与此同时,增设无功反向元件。从-X轴方向扩大动作区,以求加速失磁保护动作的做法,缺乏理论依据且欠有实效。

发电机失磁保护定值整定的讨论--对2007年版《IEEE Guide for AC Generator Protection》的斟酌

对2007年版《IEEE Guide for AC Generator Protection》中失磁保护定值整定的几个问题提出不同意见。明确指出:发电机失磁故障必有滑差(s),其平均异步阻抗Xd(js)Xd(s=0),失磁保护中的阻抗元件下端定值为-Xd,已有足够余度,不应该是-(1.1～1.25)Xd;在P-Q坐标与R-X坐标的转换公式中,U值应由"失磁保护动作滞后于低励限制线(UEL)"原则来确定,不应主观选择0.95UN。

Saturated hydrogen saline protects against noise-induced hearing loss

Objective To study effects of saturated hydrogen saline in preventing noise-induced hearing loss. Methods Fifteen guinea pigs were randomly divided into 3 groups （5 each）, group one was for control, group two was treated with normal saline and group three was treated with saturated hydrogen saline, which was given intraperitoneally at 1 hour before noise exposure at 1 ml/100 g. One hundred rounds of impulse noise （ 157 dB SPL peak） were delivered as noise exposure. Immediately after exposure to impulse noise and on Days 1, 2, 4 and 8 following exposure, auditory brainstem response （ABR） thresholds were measured. Outer hair cell morphological changes and sueeinate dehydrogenase （SDH） activity were examined on Day 8 post-exposure. Results Immediately after noise exposure, ABR thresholds in saturated hydrogen saline treated animals were lower than the non-treated animals （P 〈 0.05 ）. Microscopy showed little SDH staining, cell swelling and irregular cell arrangement in the non-treated or normal saline treated animals. Whereas in the saturated hydrogen saline treated animals, there was deep SDH staining with significantly reduced cell loss and more regular cellular arrangement compared to the other two groups. The surviving cells counts was 45.17 ±12.15 for non-treated animals, 44.50 ±10.02 for normal saline treated animals and,116.50±2.38 for animals treated with saturated hydrogen saline. While the count was similar between non-treated and normal saline treated animals, it was significantly higher in saturated sions Intraperitoneal injection of saturated hydrogen saline damage. hydrogen saline treated animals （P 〈 0.05）. Concluappears to protect the cochlea against noise-induced damage.

Islanding Protection and Islanding Detection in Low Voltage CIGRE Distribution Network with Distributed Generations

The Power Quality (PQ), security, reliability etc., are the prime objectives of the power system. The protection is developed in such a way that it should be selective, fast, reliable and the cost effective. The study about the islanding protection in Low Voltage (LV) CIGRE distribution and networks like this has been proposed in this paper. This is achieved by developing the protection against the short circuit faults which might appear at the Medium Voltage (MV) bus. The protection of the network with significant penetration of the Distributed Generations (DGs) is a complicated process. The DG units which are directly connected to the grid such as synchronous or induction generators contribute large short power, whereas the DG units which are connected to the grid via inverters carry small amount of the short circuit power. This creates the problems in the protection of the network. If the proper protection coordination measures have not been taken, it might cause the mal-function of the protection devices which put the portion of the power network into the security threats. The selection of the islanding protection devices in this paper is made to protect the network against bi-directional currents at the time of short circuit fault. The LV CIGRE distribution network will enter into islanding if a fault is cleared at the MV bus by the proposed islanding protection devices. It is therefore, essential to detect the islanding in the CIGRE power network. The detection of the island in this network is another major objective of this paper. The detection of the island is proposed by using the technique which is based on the voltage phase angle difference. The simulations are carried out by using DIgSILENT power factory software version 15.0.

Two Degree-of-Freedom Dynamic Theoretical Model on Tile Thermal Protection System

In order to study the dynamic behaviors of the thermal protection system(TPS)and dynamic strength of the strain-isolation-pad(SIP),a two degree-of-freedom dynamic theoretical model is presented under the acoustic excitation and base excitation. The tile and SIP are both considered as the elastic body and simplified as a mass point,a linear spring and a damping element. The theoretical solutions are derived,and the reasonability of theoretical model is verified by comparing the theoretical results with the numerical results. Finally,the influences on the dynamic responses of TPS by the structural damping coefficient of TPS,elasticity modulus and thickness of SIP are analyzed.The results show that the material with higher damping,and SIP with thicker size and lower elastic modulus should be considered to reduce the dynamic responses and intensify the security of TPS. The researches provide a theoretical reference for studying the dynamic behaviors of TPS and the dynamic strength of SIP. Besides,the dynamic theoretical model can be used as a quick analysis tool for analyzing the dynamic responses of TPS during the initial design phase.

Information system for emergence decision on the protection against earthquake and disaster reduction in Shanghai City──Application of GIS

For meeting the need of rapid development of economy in Shanghai and the protection against earthquake and disaster reduction in the mega city, it is necessary to build a information system for emergence decision on the protection against earthquake and disaster reduction in the city. In this paper, GIS is applied to 'the information system for emergence decision on the protection against earthquake and disaster reduction in Shanghai City (Baoshan experiment region)'. We introduce to the structure and effect of each functional module in this information system. This information system consists of 7 functional modules:background information of seismology and geology, subsystem for rapid evaluation of damage loss from earthquake, subsystem for the decisive information on earthquake emergence, information query, maintenance and management of system, help, quit. The key parts of this information system are the subsystem for rapid evaluation of damage loss from earthquake and the subsystem for the decisive information on earthquake emergence. Also, this paper introduces to the application of technology of color infra-red aerial photograph remote sensing to this information system.

Application of Temporary Technology for Soil and Water Conservation in Crop Protection

The increasing of highway engineering construction makes soil and water loss surrounding highway and also influences the growth of crops around, To control soil and water loss, new engineering measures are put forward to protect soil and water and prevent crops from being damaged.

Simulation Study of Electron Beam Induced Surface Plasmon Excitation at Nanoparticles

Phenomenon of localized surface plasmon excitation at nanostructured materials has attracted much attention in recent decades for their wide applications in single molecule detection,surface-enhanced Raman spectroscopy and nano-plasmonics.In addition to the excitation by external light field,an electron beam can also induce the local surface plasmon excitation.Nowadays,electron energy loss spectroscopy(EELS)technique has been increasingly employed in experiment to investigate the surface excitation characteristics of metallic nanoparticles.However,a present theoretical analysis tool for electromagnetic analysis based on the discrete dipole approximation(DDA)method can only treat the case of excitation by light field.In this work we extend the DDA method for the calculation of EELS spectrum for arbitary nanostructured materials.We have simulated EELS spectra for different incident locations of an electron beam on a single silver nanoparticle,the simulated results agree with an experimental measurement very well.The present method then provides a computation tool for study of the local surface plasmon excitation of metallic nanoparticles induced by an electron beam.

Design and Research of Efficient Adaptive Spray Plant Protection UAV

When the plant protection UAV is spraying on plants, the operator usually performs visual inspection on the vertical distance between the UAV and the plant to adjust the spray height to complete the application. Visual inspection by human eyes is easy to cause the error of spray deposition and deposition density. In order to improve the full utilization of drugs and the spraying efficiency of plant protection UAV, an efficient adaptive spray plant protection UAV was designed, and the vertical distance from the UAV to the plant was collected by ultrasonic wave. Meantime, the plant density was detected in real time, and the flight attitude of plant protection UAV and application rate of spray nozzle were automatically adjusted. The experimental results showed that the designed highly efficient adaptive spray plant protection UAV had fast response speed, precise spray location and less drug loss.

Ideas of establishing the information system for emergence decisions on the protection against earthquakes and disaster reduction in cities (application of GIS)

ith urban reformation and opening becoming deeper,the work of protection against earthquake and disaster reduction would be more important.In this paper,some ideas are suggested about establishing the information system for emergency decisions on protection against earthquake and disaster reduction in cities .The information system mainly includes a subsystem for rapid evaluation of damage loss from earthquake (which includes input of seismic information,distribution of earthquake intensity,evaluation of seismic fragility on all social factors and etc.) and a subsystem for the decisive information of seismic emergency(which mainly includes project of disaster relief,project of personnel evacuation,dangerous degree warning for the dangerous articlesstoring places and protection measures against them,assistant decision on fire due to earthquake,location of headquarter for providing disaster relief,and etc.). It is thought that the data investigation and collection about all kinds of buildings(including lifeline engineering)are the most important and difficult work as establishing this system.

Study on the Determination of the Significant National Seismic Monitoring and Protection Regions

The paper describes firstly the principles and scientific train of thought involved in determining the significant seismic monitoring and protection regions (SSMPR) in China. The principles include the gradation principle, i.e. the national level SSMPR and the provincial level SSMPR, the principle of highlighting priorities, namely, the area of an SSMPR should be a fraction of the total area of the country or of the respective province, but the earthquake losses incurred in SSMPR should be a major proportion of the national or provincial ones. The scientific train of thought adopted is to determine the SSMPR on the basis of seismic hazard assessment and loss estimation. Secondly, it reviews the achievements in determining the SSMPRs for the period from 1996 to 2005. The result shows that 10 strong earthquakes occurred during that period in the areas with earthquake monitoring and prediction capability available on the Chinese continent, 8 of which occurred in SSMPRs with the economic loss and death toll accounting for 67% and 92% of the total loss on the Chinese mainland. Lastly, the paper introduces preparatory research for determining the SSMPR for the period from 2006 to 2020, including decade-scale mid-and long-range seismic risk assessment based on seismology, seismogeology, geodesy, earthquake engineering, sociology and stochastics and so on, and the national seismic risk probability map, the seismic hazard (intensity) map, earthquake disaster losses map and the comprehensive seismic risk index, etc. obtained for the period of 2006 to 2020.

The Double Excitation： A Solution to Improve Energetic Performances of High Power Synchronous Machines

DFSM （doubly fed synchronous machine） presents several advantages such as efficiency improvement, weight reduction and increase of the utilization factor （kW/kg）. In this paper the authors focus on impact of the DFSM on the efficiency and machine weight in comparison to conventional synchronous generator with wound rotor. Different topologies of DFSM are briefly described and the different methods and models for performances prediction are presented.

Influence of DFIG Wind Turbine Protection and Control during Voltage Dip on Circuit Breaker Operation

This paper analyzes a DFIG （doubly fed induction generator） WT （wind turbine） fault current after a symmetrical network voltage dip. The goal is to identify the factors determining how fast the first zero crossings of the fault current occur. This is an important subject because the ftmdamental property of the CB （circuit breaker） is that it breaks the current when the current is very near zero. The study was conducted using a hardware-in-the-loop test environment constructed using two real time simulators （dSPACE and RTDS） and a commercial protection relay. It is found that the reactive current injection during a voltage dip demanded by the grid codes enhances the operation of the WT protection because the zero crossings of the currents through CB are attained earlier. In addition, the size of the crowbar resistance has a significant influence on the zero crossings.

Energy loss of degrader in SC200 proton therapy facility

The proton beam energy determines the range of particles and thus where the dose is deposited. According to the depth of tumors, an energy degrader is needed to modulate the proton beam energy in proton therapy facilities based on cyclotrons, because the energy of beam extracted from the cyclotron is fixed. The energy loss was simulated for the graphite degrader used in the beamline at the superconducting cyclotron of 200 MeV in Hefei(SC200). After adjusting the mean excitation energy of the graphite used in the degrader to 76 eV, we observed an accurate match between the simulations and measurements.We also simulated the energy spread of the degraded beam and the transmission of the degrader using theoretical formulae. The results agree well with the Monte Carlo simulation.

QUANTUM-CHEMICAL MODIFICATIONS OF SURFACE:NEW METHODS FOR PROTECTING MATERIALS FROM CORROSION

A new method of corrosion-resistant coating of technical iron is presented. Processing by vibrationally excited hydrogen molecules of the iron surface covered with oxide film of α-Fe2 03 results in modification of surface by creating a film of amorphous iron on it. The presence of iron films with crystalline and amorphous phases, having the different Fermi levels, leads to formation of potential differences between them. This potential difference is opposite to the external electric field, resulting in decrease of anode current and increase of corrosion resistance.

The Extent and Effectiveness of Protected Areas in the Russian Federation

To tackle environmental challenges and in particular,the problems associated with the high demand for forests and resources,the consequence of which is the degradation of ecological systems,Russia has developed the biggest network of specially protected natural areas in the world.Although the scale of SPNA may look impressive,a recent comprehensive study of the period from 2001 to 2018 brought the spotlight on protected areas in Russia experiencing significant tree loss annually.Since Russia is confronting unprecedented fires that break records every year,the problem of preserving rare animal and plant species,their habitats,and natural ecosystems is acute.This paper is intended to assess the extent and effectiveness of SPNAs with regard to wilderness conservation in the Russian Federation based on the latest data;the main focus being on the period of 2014—2019,before and after the launch of the environmental safety strategies,along with additional analysis of available data for the following year of 2020.With due consideration of unique geographical,economic,and socio-cultural circumstances,as well as historical background and legislative reality of SPNAs in Russia,we have conducted a statistical analysis of data from the official annual reports from the Federal State Statistics Service on SPNAs by territories and significance,expenditures on maintenance and ecotourism,followed by RGB analysis of satellite imagery via means of GIS software for visualization of obtained data and further analytics.Despite the growth of the SPNA network in Russia,resulting in an astonishing 2402 Mha in 2020,an estimated 4 Mha of tree loss accounted for SPNAs over the period of 2014—2019,and 134 Mha in 2020 alone.Our findings indicate a need for the application of a comprehensive GIS approach for further development and effective management of the SPNA network in Russia.Furthermore,the results include recommendations on legislative changes,engagement of locals in SPNA protection,and popularization of ecotourism,all of which can be valuable for policymakers and SPNA development.

Reimagining the Visceral Protective Layer with Tailored Manipulation: A Case Report

The visceral protective layer is a standard component of the ABTHERATM systems for temporary abdominal closures. Nonetheless, there are circumstances where the standard, fenestrated visceral protective layer is too large to be successfully applied into every patient’s open abdomen, such as within the abdomen of a child, smaller adult or a patient with previously placed ostomies or drains. The fenestrated, visceral protective layer may require alterations or tailoring for adequate deployment instead of placing the bulk of the visceral protective layer entirely into the open abdomen for temporary abdominal closure. This case report illustrates how the visceral protective layer can be adapted or “reimagined” to conform to a patient with unique or complex abdominal domain features when utilizing the ABTHERATM device prior to facial closure or abdominal wall reconstruction. Photographs are utilized in a step-by-step fashion to aid the clinician in these detailed maneuvers.

某冶金制造企业噪声暴露对听力水平的影响

目的探讨冶金制造业噪声暴露对听力水平的影响。方法对某企业245名噪声暴露工人及51名行政人员进行双耳0.5~8 kHz纯音气导听阈测试,检测工作场所噪声8 h等效声级,统计分析不同工种工人听力阈值。结果噪声暴露工人0.5~8 kHz听力阈值均显著高于行政人员;听力受损主要发生在4、6 kHz;听力阈值与工龄、年龄正相关,40岁以上、6年以上工龄,工人双耳4、6 kHz听力阈值均高于40 dB HL。结论噪声暴露工人4、6 kHz听力损伤最明显,年龄、工龄、噪声暴露强度是听力受损的危险因素。应加强噪声源的控制,重视耳塞等防护措施,并减少噪声暴露时间。

高频多谐波激励下计及趋肤效应的软磁带材磁滞及损耗特性预测

软磁材料的非线性磁化特性使得软磁带材涡流场分布及其损耗特性分析十分困难。为此,该文采用分段线性的方法对基本磁化曲线进行逼近,基于麦克斯韦方程在每个线性段进行推导,得到单频正弦激励下软磁带材中与涡流损耗相对应的平均磁场强度Hcl表达式,并提出相应的参数辨识方法。进而,基于场分离技术与损耗分离的一致性原理,建立场分离形式的高频动态磁滞模型。根据实际应用中的高次谐波特征,基于磁导率的近似线性特征和场量的叠加原理,构造描述多谐波激励下与涡流损耗相对应磁场强度Hcl的解析表达式,并进一步提出软磁带材在复杂多谐波激励下的动态磁滞预测模型。通过实验结果与仿真结果的对比,验证该文所提方法的有效性和准确性。