Effect of Nonlinearities in Turbine Governor System on Torsional Oscillation Stability

ＥｆｅｃｔｏｆＮｏｎｌｉｎｅａｒｉｔｉｅｓｉｎＴｕｒｂｉｎｅＧｏｖｅｒｎｏｒＳｙｓｔｅｍｏｎＴｏｒｓｉｏｎａｌＯｓｃｉｌａｔｉｏｎＳｔａｂｉｌｉｔｙＹＵＤａｒｅｎ（于达仁）ＢＡＯＷｅｎ（鲍文）ＸＵＪｉｙｕ（徐基豫）Ｄｅｐｔ．ｏｆＰｏｗｅｒＥｎｇｉｎ...

Analysis of Nonlinear Characteristics of Turbine Governor and Its Impact on Power System Oscillation

In this paper, the model of turbine governor?based on the physical principles is constituted to improve the accuracy of power system dynamic simulation, making the results of simulation consistent with the actual situation. The unit and grid coupling model which reflects the interaction between thermal system of power plant and power system is built using EMTDC/PSCAD. The influence of nonlinear characteristics on the valve opening and the steam turbine mechanical power is also analyzed in this paper. The results of simulation show that the improper setting of parameters reflecting nonlinear characteristics of turbine governor can lead to the cyclical oscillations of the valve opening and the?steam turbine mechanical power, and even can lead to the power oscillation persistently. The research achievements in this paper have a certain reference value on exploring the causes of power oscillation from the prime mover.

Francis Turbine and Governor Improved Models Considering Step Closing Law of Guide Vanes for Power System Stability Analysis

The Francis turbine governing system models in PSD-BPA can’t precisely reflect the actual characteristics. Endeavor was done in this paper to solve the problem. An improved model of actuating mechanism was developed, which could reflect the step closing characteristic of hydro guide vanes. The effect of the inflection point value of actuating mechanism on load rejection was analyzed based on simulation. The non-linear Francis turbine model with power versus gate position module was researched in this paper. Based on field test, comparisons of simulation results with measured data were presented. The analysis demonstrates that the improved models of Francis turbine and governor proposed in this paper are more realistic than the models of BPA, and can be applied in power system simulation analysis better.

调压井底孔对水轮机调节系统过渡过程的影响

调压井是水电站建设的重要工程措施,本文在对带调压井的水轮机调节系统开展的计算分析中,采用流量、力矩的特征矩阵法描述水轮机特性、详细考虑了水轮机调速器非线性特性(如主配压阀速度特性、接力器开关时间整定引起的严重的非线性特性等),用实际甩负荷过渡过程算例说明调压井底孔阻尼对水轮机调节系统振荡特性的衰减、调压井内水位涌升的重要影响。

乾隆时期督抚题调制度谫论

乾隆时期,清廷构建了较为完备的督抚题调制度,乾隆帝一方面出于地方治理的现实需求,在构建稳定制度体系的同时也给予督抚一定合理的运作空间,在一定程度上赋予了题调制度较大的弹性空间。另一方面,督抚题调权力的行使,也被置于吏部核查的制度之下,呈现出皇帝、督抚、吏部三者之间权力交织、相互博弈的政治格局。随着督抚用人环境日渐紧张,乾隆初期构建的相对有序的督抚题调制度也日渐被破坏,“率请捐复”“私下调署”之风愈演愈烈,成为清代后期地方督抚势力上升的一个重要诱因。

财政分权、粮食安全省长责任制与粮食生产

财政分权作为调控地方资源配置的重要制度安排和国家治理的重要手段,对治理成效的影响日益凸显,对地方粮食生产的作用不可忽视。在理论分析基础上,基于2004—2020年中国31个省份(不含港澳台地区)的面板数据,实证检验财政分权对粮食生产的影响,并分析粮食安全省长责任制对上述两者关系的调节作用。结果发现,财政分权显著削弱了粮食生产;粮食安全省长责任制对财政分权与粮食生产之间的调节关系存在区域异质性,有效抑制了财政分权对粮食主产区、中部和西部地区粮食生产的削弱,但加剧了财政分权对非主产区和东部地区粮食生产的削弱。为稳定各地粮食生产、保障国家粮食安全,提出三方面政策建议:一是优化财政分权制度,加强地方支粮财政支出;二是优化粮食安全省长责任制内容,提高地方粮食生产;三是加大地方考核中粮食安全权重,提高地方抓粮积极性。

从“征伐”到“坐镇”:明代宣大总督的设置过程

明代的宣大总督并非只是简单地设置与裁撤,而是经历了派遣、设置与派遣反复、定设的演变过程。定设之前的宣大总督,置身于京营征伐体制之中,监军太监、总督文臣、征伐总兵三者共同负责征伐事务,但这一体制运行成本高昂,遂有设置总督文臣于边地先期措理边务、京营出征待定的举措。随着京营的日益衰弱和边军实力的增强,京营的出征变得没有必要,总督文臣最终定设于宣大山西地区。

灯泡贯流式水轮发电机组调速器液压油外泄监测报警系统探讨

本研究旨在设计一种基于灯泡贯流式水轮发电机组调速器液压油外泄漏监测报警系统,以解决水轮机调速器液压油外泄漏所带来的危害。介绍了灯泡贯流式水轮发电机组调速器液压系统的原理及构成;分析了调速器液压系统液压油外泄漏的特征及危害。设计了一种监测报警系统,阐述了其工作原理、构成、功能、特点及调试方法,并总结了研究的主要观点和意义。

Electro-acupuncture at Conception and Governor vessels and transplantation of umbilical cord bloodderived mesenchymal stem cells for treating cerebral ischemia/reperfusion injury

Mesenchymal stem cell transplantation is a novel means of treating cerebral ischemia/reper- fusion, and can promote angiogenesis and neurological functional recovery. Acupuncture at Conception and Governor vessels also has positive effects as a treatment for cerebral ischemia/ reperfusion. Therefore, we hypothesized that electro-acupuncture at Conception and Governor vessels plus mesenchymal stem cell transplantation may have better therapeutic effects on the promotion of angiogenesis and recovery of neurological function than either treatment alone. In the present study, human umbilical cord blood-derived mesenchymal stem cells were isolated, cultured, identified and intracranially transplanted into the striatum and subcortex of rats at 24 hours following cerebral ischemia/reperfusion. Subsequently, rats were electro-acupunctured at Conception and Governor vessels at 24 hours after transplantation. Modified neurological severity scores and immunohistochemistry findings revealed that the combined interventions of electro-acupuncture and mesenchymal stem cell transplantation clearly improved neurological impairment and up-regulated vascular endothelial growth factor expression around the isch- emic focus. The combined intervention provided a better outcome than mesenchymal stem cell transplantation alone. These findings demonstrate that electro-acupuncture at Conception and Governor vessels and mesenchymal stem cell transplantation have synergetic effects on promot- ing neurological function recovery and angiogenesis in rats after cerebral ischemia/reperfusion.

Effects of decompression joint Governor Vessel electro-acupuncture on rats with acute upper cervical spinal cord injury

Decompression is the major therapeutic strategy for acute spinal cord injury,but there is some debate about the time window for decompression following spinal cord injury.An important goal and challenge in the treatment of spinal cord injury is inhibiting or reversing secondary injury.Governor Vessel electroacupuncture can improve symptoms of spinal cord injury by inhibiting cell apoptosis and improving the microenvironment of the injured spinal cord.In this study,Governor Vessel electroacupuncture combined with decompression at different time points was used to treat acute spinal cord injury.The rat models were established by inserting a balloon catheter into the atlanto-occipital space.The upper cervical spinal cord was compressed for 12 or 48 hours prior to decompression.Electroacupuncture was conducted at the acupoints Dazhui（GV14） and Baihui（GV 20）（2 Hz,15 minutes） once a day for 14 consecutive days.Compared with decompression alone,hind limb motor function recovery was superior after decompression for 12 and 48 hours combined with electroacupuncture.However,the recovery of motor function was not significantly different at 14 days after treatment in rats receiving decompression for 12 hours.Platelet-activating factor levels and caspase-9 protein expression were significantly reduced in rats receiving electroacupuncture compared with decompression alone.These findings indicate that compared with decompression alone,Governor Vessel electroacupuncture combined with delayed decompression（48 hours） is more effective in the treatment of upper cervical spinal cord injury.Governor Vessel electroacupuncture combined with early decompression（12 hours） can accelerate the recovery of nerve movement in rats with upper cervical spinal cord injury.Nevertheless,further studies are necessary to confirm whether it is possible to obtain additional benefit compared with early decompression alone.

Present Status of Solid Waste Management at Babylon Governorate, Iraq

Babylon Governorate covers an area of 5315 km2 with a population that reaches about 1,974,490 inhabitants in the central part of Iraq. Iraq produced 31,000 tons/day solid waste in 2013. The Governorate of Babylon produces annual 483,221 tons of solid waste. Management of collection and disposal of waste in Babylon Governorate is done through open dumping of waste and poor collection process. These sites do not conform to the scientific and environmental criteria applied in the selection of landfill sites. To find out how much solid waste is expected in the future, two methods were used to calculate the population growth in Babylon Governorate to the year 2030. The results showed that the total waste in 2030 will be 761,104 tons and 943055 tons while the cumulated quantity of solid waste expected till 2030 was 12,494,521 tons and 14,095,437 tons according to the first and second methods respectively.

CLINICAL STUDIES ON CEREBRAL INFARCTION TREATED WITHACUPUNCTURE AT ACUPOINTS OF GOVERNOR MERIDIAN

In this paper, 148 cases of cerebral infarction were treated with acupuncture at acupoints of Governor meridian (treatment group), and the other 97 cases were treated simultaneously with conventional body acupuncture (control group). The results show that the marked improvement rate was 42. 6 % and the total effective rate was 96. 6 % in the treatment group; while in the control group, the marked improvement rate and the total effective rate were 28. 9 % and 89. 1 % respectively.It suggests that the therapeutic effect in the treatment group is better than that of the control group.The roles of regulation and ameliorating hemorheology of acupuncture at acupoints of Governor meridian are the foundation of its treatment mechanism.

Assessment of the Hydrogeochemical Characteristics of Groundwater Resources at some Wadis in the East of El Minia Governorate,Eastern Desert,Egypt

The El Minia governorate lies within the Nile Valley,surrounded by calcareous plateaus to the east and west.The present study focuses on the hydrogeochemistry of the Eocene limestone aquifer at some wadis in the east El Minia governorate,Eastern Desert,Egypt.Hydrogeologically,two main aquifers are encountered in the study area,namely the Maghagha marly limestone and the Samalut chalky limestone aquifers.The Maghagha aquifer is composed of alternating layers of marly limestone and shale with thicknesses ranging from 3.49 m to 177.05 m and a groundwater depth ranging from 8.5 m to 59.27 m which reflects low groundwater potentiality.The groundwater salinity representing this aquifer ranges from 603.5 mg/L to 978.5 mg/L,reflecting fresh water type.Samalut aquifer is made up of chalky,cavernous and fractured limestone with thickness ranging from 30 m to 205 m and groundwater depth ranging from 9 m to 86.77 m,which indicates good groundwater potential.The groundwater salinity of the concerned aquifer ranges from 349.7 mg/L to 2043.9 mg/L,reflecting fresh to possibly brackish water types.Groundwater in the study area is of meteoric water origin;recent recharge is mainly controlled through the presence of fractures and their densities.The majority of groundwater samples in the study area are suitable for drinking and irrigation purposes.

A Century of Monitoring Urban Growth in Menofya Governorate, Egypt, Using Remote Sensing and Geographic Information Analysis

Urban growth is a global phenomenon mainly driven by the overpopulation growth particularly in developing countries like Egypt. Pattern and extent of urban growth could be monitored and modelled on a spatial and temporal dimension. GIS and remote sensing data along with other thematic maps were used to analyze the urban growth, pattern and extent in the last century in one of the biggest governorates at the heart of the Nile Delta of Egypt. Both spatial and temporal analyses enabled to identify the pattern of urban growth and subsequently project the nature of future growth. However, the overall urban growth in the last century was 12 times the original built up areas in 1910;the third stage from 1950 to 1972 was the highest stage of urban growth with 124% increase of the built-up area. The dominant pattern of urban growth was linear along highways and railways with majority to the North, North East and North West directions. The study developed a spatial model to project urban growth by 2027, indicating that urban growth in the Menofya Governorate would be continued at the same directions with the same pattern with an estimated increase of 33%. The study provided an understanding of the controlling factors which drove the urban growth along this long time.

MODELING AND IMPLEMENTATION OF SPEED GOVERNOR FOR THE HYBRID ELECTRIC VEHICLE ENGINE

A speed control analysis for an in-line gasoline fueled internal combustion （IC） engine is presented for the purpose of alleviation of high frequency oscillations in engine revolutions. A dynamic cylinder-by-cylinder model is proposed, base on slider-crank mechanism, which is extended to develop a digital governor providing a high fidelity estimation of rotary speed oscillation for hybrid vehicle engines. A modified PID controller that P and I gain is placed in feedback path is also described for hybrid electric vehicle （HEV） engine speed regulation, By comparison between measured and estimated signals, it is demonstrated that a good agreement has been achieved and the governor behaves an excellent damping speed ripple.

从governor与governess的区别谈起

英语中有这样一些词，它们成对，且在语义上相等，只不过一个专指男性．另一个专指女性。这些词就是我们所熟悉的sex—paired words。如：host—hostess，actor-actress，husband—wife．hero—heroine等。这些词不仅在语义上相等，而且存使用中具有对称性.

CLINICAL OBSERVATION ON TREATMENT OF 205 CASES OF CERVICAL SPONDYLOPATHY BY ACUPUNCTURE AND MOXIBUSTION ON THE GOVERNOR VESSEL OF THE NECK

This article involves 325 patients suffering from cervical spondylopathy,amongthem 205 cases were treated by acupuncture and moxibustion on the governor vessel of the neck（treatment group）,the other 120 cases were treated by common acupuncture（control group）.Itwas observed that the cure rate,the total effective rate was 91.2％,98.5％ in the treatmentgroup,and 55.8％,87.5％ in the control group.There were statistically significant differences（P【0.01）in the cure rate and total effective rate between the two groups.It is concluded thatacupuncture and moxibustion on the governor vessel of the neck may improve Yang Qi circulationwithin the Dumai and promote the micro-circulation in the diseased areas.Thus it evidently in-creases the therapeutic effects.

Study on Calibrating of Electronic Governors

The control parameters of electronic governor that influence the transient characteristics of the engine are analyzed.An electric control unit was developed and the control parameters were calibrated on the test bench.The initial value of integral term and the maximum output of rack position proportion,integration and derivation（PID）controller affect the step and triangle response drastically.Through correcting the proportional term and integral term of speed PID controller,the dynamic speed drop and speed overshoot are improved.A property control strategy for cold starting an engine is set,and the calibration process indicates that the fuel injected into the cylinder per cycle and the desired speed ascend rate drastically affect the start transient process.

Recent Activities of the Board of Governors of Acta Materialia Inc.

July 2007-July 2008 This report highlights the actions, discussions, and the general activities of the Board of the Governors of Acta Materialia Inc. over the past year. It covers the Board

Research on the Influence Factors and Coordinated Control Strategies between Unit and Grid for Isolated Power System

As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated system operation. This paper analyzes the power grid side and unit side influence factors on the isolated power system. The dynamic models which are suitable for islanding operation are applied to simulate and analyze the stability and dynamic characteristics of the isolated power system under the conditions of different load disturbances and governor parameters. With considering the differences of frequency characteristics between the interconnected and isolated power system, the adjusting and optimization methods of under frequency load shedding are proposed to meet the frequency stability requirements simultaneously in the two cases. Not only proper control strategies of the power plant but the settings of their parameters are suggested to improve the operation stability of the isolated power system. To confirm the correctness and effectiveness of the method mentioned above, the isolated system operation test was conducted under the real power system condition, and the results show that the proposed coordinated control strategies can greatly improve stability of the isolated power system.