期刊文献+
共找到3,415篇文章
< 1 2 171 >
每页显示 20 50 100
基于迭代Reference Governor的自由活塞发动机活塞运动控制 被引量:2
1
作者 宫洵 胡云峰 +1 位作者 杨荣彬 陈虹 《控制理论与应用》 EI CAS CSCD 北大核心 2017年第2期188-196,共9页
精确的活塞运动控制是实现自由活塞发动机(free piston engine,FPE)安全可靠运行的前提,本文的主要研究内容是带有约束的FPE活塞运动控制.根据活塞运动控制问题描述,建立了FPE面向控制的非线性离散模型;设计状态反馈控制器,通过控制循... 精确的活塞运动控制是实现自由活塞发动机(free piston engine,FPE)安全可靠运行的前提,本文的主要研究内容是带有约束的FPE活塞运动控制.根据活塞运动控制问题描述,建立了FPE面向控制的非线性离散模型;设计状态反馈控制器,通过控制循环喷油量使活塞运动位置跟踪期望值;针对电磁负载变化引起的活塞运动瞬态波动超出安全约束的问题,考虑闭环系统非线性隐式的特点,在不改变原状态反馈控制的框架下,提出基于牛顿迭代的Reference Governor来调节负载,保证系统运动满足安全约束.所提出的控制方法为带有约束FPE活塞运动控制提供解决方案的同时,扩展了Reference Governor算法在隐式系统的应用.通过MATLAB与AMESim联合仿真验证了控制方法的有效性. 展开更多
关键词 自由活塞发动机 活塞运动控制 Referencegovernor 约束
下载PDF
Electro-acupuncture at Conception and Governor vessels and transplantation of umbilical cord bloodderived mesenchymal stem cells for treating cerebral ischemia/reperfusion injury 被引量:14
2
作者 Haibo Yu Pengdian Chen +4 位作者 Zhuoxin Yang Wenshu Luo Min Pi Yonggang Wu Ling Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第1期84-91,共8页
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 als... 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. 展开更多
关键词 nerve regeneration acupuncture human umbilical cord blood-derived mesenchymalstem cells ELECTRO-ACUPUNCTURE cerebral ischemia/reperfusion vascular endothelial growth factor angiogenesis Conception vessel governor vessel modified neurological severity score NSFC grant neural regeneration
下载PDF
Effects of decompression joint Governor Vessel electro-acupuncture on rats with acute upper cervical spinal cord injury 被引量:8
3
作者 Yan-Lei Wang Ying-Na Qi +5 位作者 Wei Wang Chun-Ke Dong Ping Yi Feng Yang Xiang-Sheng Tang Ming-Sheng Tan 《Neural Regeneration Research》 SCIE CAS CSCD 2018年第7期1241-1246,共6页
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 treatme... 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. 展开更多
关键词 nerve regeneration acute spinal cord injury decompression governor Vessel electroacupuncture platelet-activating factor apoptosis methylprednisolone caspase family upper cervical spine animal model Basso Beattie and Bresnahan locomotor scale neural regeneration
下载PDF
A Practical Approach of Developing Mathematical Model for All Speed Governors 被引量:3
4
作者 王永生 Dennis N.Assanis 张煜盛 《Journal of Shanghai Jiaotong university(Science)》 EI 2005年第2期175-181,共7页
The paper introduced a special approach for diesel’s all-speed-governor modeling, which, in some cases, could solve the knotty problem frequently met in computer simulation of diesel propulsion system or diesel gener... The paper introduced a special approach for diesel’s all-speed-governor modeling, which, in some cases, could solve the knotty problem frequently met in computer simulation of diesel propulsion system or diesel generating set. Suppose that it is hard to get a control-oriented governor mathematical model when the general approaches, the analytical approach or the experimental approach, are applied, and that an open-loop step response of the diesel engine and its system is available by means of computer simulation, the critical three parameters of a governor mathematical model, the proportional gain K_p, integral time constant K_i, and derivative time constant K_d, can be determined by use of PID tuning method which are widely applied in industrial process control. This paper discussed the train of thought of the approach, precondition, procedure, several modifications of the classical PID model, and some points for attention. A couple of case studies were given to demonstrate the effectiveness of this approach. 展开更多
关键词 computer simulation mathematical model diesel engine speed governor PID controller
下载PDF
Present Status of Solid Waste Management at Babylon Governorate, Iraq 被引量:5
5
作者 Ali Chabuk Nadhir Al-Ansari +2 位作者 Hussain Musa Hussain Sven Knutsson Roland Pusch 《Engineering(科研)》 2015年第7期408-423,共16页
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 prod... 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. 展开更多
关键词 BABYLON governorate SOLID WASTE MANAGEMENT WASTE DISPOSAL SITES Iraq
下载PDF
CLINICAL STUDIES ON CEREBRAL INFARCTION TREATED WITHACUPUNCTURE AT ACUPOINTS OF GOVERNOR MERIDIAN 被引量:1
6
作者 许能贵 张闻东 梁兴伦 《World Journal of Acupuncture-Moxibustion》 1997年第3期21-25,共5页
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 ... 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. 展开更多
关键词 ACUPUNCTURE ACUPOINTS of governor MERIDIAN Cerebral INFARCTION
下载PDF
Effect of Nonlinearities in Turbine Governor System on Torsional Oscillation Stability 被引量:1
7
作者 于达仁 鲍文 徐基豫 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1997年第2期25-29,共5页
There are several different nonlinearities in the turbine governor system, such as insensitivity, saturation of servo system, and frequency modulation dead band, which reduce the interaction between the governor syste... There are several different nonlinearities in the turbine governor system, such as insensitivity, saturation of servo system, and frequency modulation dead band, which reduce the interaction between the governor system and torsional oscillation, and thereby improve the torsional oscillation stability of shafts. This paper suggests intentional incorporation of appropriate nonlinearities in the governor system to improve the torsional oscillation stability of shafts. 展开更多
关键词 TURBINE governor NONLINEARITY torsional OSCILLATION
下载PDF
Assessment of the Hydrogeochemical Characteristics of Groundwater Resources at some Wadis in the East of El Minia Governorate,Eastern Desert,Egypt 被引量:1
8
作者 Alzahraa Abo HABIBAH Kamal DAHAB +2 位作者 Ashraf SHABANA Samir KAMH Hekmat IBRAHIM 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2022年第3期1082-1097,共16页
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 ... 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. 展开更多
关键词 GROUNDWATER limestone aquifers El Minia governorate Eastern Desert
下载PDF
A Century of Monitoring Urban Growth in Menofya Governorate, Egypt, Using Remote Sensing and Geographic Information Analysis 被引量:1
9
作者 Islam Abou El-Magd Ahmed Hasan Abdelfatah El Sayed 《Journal of Geographic Information System》 2015年第4期402-414,共13页
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 tempo... 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. 展开更多
关键词 URBAN Growth GIS REMOTE Sensing Modelling Menofya governorate EGYPT
下载PDF
MODELING AND IMPLEMENTATION OF SPEED GOVERNOR FOR THE HYBRID ELECTRIC VEHICLE ENGINE 被引量:1
10
作者 Feng Qishan Zhang Jianwu Yin Chengliang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2005年第4期603-608,共6页
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-cylinde... 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. 展开更多
关键词 Digital speed governor Engine dynamic model Slider-crank mechanism Hybrid electric vehicle (HEV)
下载PDF
CLINICAL OBSERVATION ON TREATMENT OF 205 CASES OF CERVICAL SPONDYLOPATHY BY ACUPUNCTURE AND MOXIBUSTION ON THE GOVERNOR VESSEL OF THE NECK
11
作者 龚维义 储浩然 《World Journal of Acupuncture-Moxibustion》 1996年第4期3-7,共5页
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 t... 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. 展开更多
关键词 Cervical SPONDYLOPATHY Acup and MOX therapy governor vessel NECK
下载PDF
从governor与governess的区别谈起
12
作者 陆琳 《大学英语》 2004年第5期30-30,共1页
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... 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. 展开更多
关键词 governor GOVERNESS 区别 英语 语义 用法 词汇
下载PDF
Study on Calibrating of Electronic Governors
13
作者 黄千 黄英 张付军 《Journal of Beijing Institute of Technology》 EI CAS 2009年第3期288-292,共5页
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 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. 展开更多
关键词 power machinery engineering control strategy cascade control electronic governor
下载PDF
Analysis of Nonlinear Characteristics of Turbine Governor and Its Impact on Power System Oscillation
14
作者 Ge Jin Hanting Yan +2 位作者 Shaoxiang Deng Xiaomei Chen Zexiang Cai 《Energy and Power Engineering》 2013年第4期746-750,共5页
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 situ... 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. 展开更多
关键词 TURBINE governor Modeling NONLINEAR Characteristics POWER System OSCILLATION
下载PDF
Experimental Study of a Modified Command Governor Adaptive Controller for Depth Control of an Unmanned Underwater Vehicle
15
作者 Charita D.Makavita Shantha G.Jayasinghe +1 位作者 Hung D.Nguyen Dev Ranmuthugala 《Journal of Marine Science and Application》 CSCD 2021年第3期504-523,共20页
Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with param... Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications. 展开更多
关键词 Command governor adaptive control Measurement noise Time delay Transient tracking Unmanned underwater vehicles ROBUSTNESS
下载PDF
Recent Activities of the Board of Governors of Acta Materialia Inc.
16
《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2008年第5期389-390,共2页
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
关键词 over Recent Activities of the Board of governors of Acta Materialia Inc GOLD
下载PDF
Measuring the Public Awareness toward Household Waste Management in Muharraq Governorate-Kingdom of Bahrain
17
作者 S. Y. Abbas K. Kirwan D. Lu 《Journal of Environmental Protection》 2020年第3期196-214,共19页
Municipal Solid Waste (MSW) generation is growing rapidly as compared to the rate of urbanization. Household waste management is considered a highly challenging task for Bahrain’s policy-makers, urban planners and mu... Municipal Solid Waste (MSW) generation is growing rapidly as compared to the rate of urbanization. Household waste management is considered a highly challenging task for Bahrain’s policy-makers, urban planners and municipalities due to rising population, burgeoning growth rate of waste generation, limited availability of land and scarce waste disposal sites. Public awareness represents a key enabler in order to succeed any sustainable waste management practice in the country. The survey aimed at gauging public awareness about household waste management in Muharraq Governorate and explored if there are any correlations between educational level, gender, occupation and age and area of living with the level of public awareness as well as its three components: knowledge, attitude and behaviour of the people in Muharraq Governorate. The results indicated the total awareness is significantly different across different age levels and nationality. Moreover, it shows a high public awareness toward household waste management among people in Muharraq Governorate, which indicated that the society is aware and has the basics to build on in terms of sustainable waste management practices and technologies adoption, which may help overcome the possible social barrier represented by low public awareness. 展开更多
关键词 PUBLIC AWARENESS HOUSEHOLD Waste MANAGEMENT ATTITUDE Behaviour KINGDOM of Bahrain Muharraq governorate
下载PDF
Francis Turbine and Governor Improved Models Considering Step Closing Law of Guide Vanes for Power System Stability Analysis
18
作者 Yuheng Tang 《Journal of Power and Energy Engineering》 2014年第9期125-131,共7页
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,... 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. 展开更多
关键词 FRANCIS TURBINE governor Actuating Mechanism STEP CLOSING LAW Improved Models Power System Stability Analysis
下载PDF
Impact of Islanding on Governor Signal of Distributed Resources
19
作者 Mahdi Ghadiri Ali Moeini Hossein Yassami 《Journal of Electromagnetic Analysis and Applications》 2011年第2期56-64,共9页
Technical and economical impacts of distributed resources have encouraged big industry managers and distribution systems’ owners to utilize small type of electric generations. One important preventive issue to develo... Technical and economical impacts of distributed resources have encouraged big industry managers and distribution systems’ owners to utilize small type of electric generations. One important preventive issue to develop these units is islanding situation. Expert diagnosis system is needed to distinguish network cut off from normal occurrences. It should detect islanding in time to disconnect the unit and prevent any additional failures in equipment. An important part of synchronous generator is automatic load-frequency controller (ALFC). This controller is designed properly to respond to load variations and to fix frequency at constant value when working alone as an islanding system and to control output power when operating in parallel with the main. In this paper, a new approach based on monitoring ALFC re-sponse with regard to input signal to governor is introduced. Numbers of initial crossing value are introduced as an index for islanding detection. Simulation results show that input signal to governor has different characteristics in common disturbances. 展开更多
关键词 Automatic Load Frequency CONTROLLER Distributed Generation governor ISLANDING Detection INITIAL VALUE CROSSING
下载PDF
Knowledge &Utilization of Long Lasting Impregnated Nets among Housewives in Al Moneera City and Al Koozi Villages, Hodieda Governorate, Republic of Yemen 2007
20
作者 Nahid A. Baktayan Ali M. Assabri +1 位作者 Belquis A. Farea Arwa A. Farea 《Health》 2021年第3期306-322,共17页
Malaria is considered as one of the main health problem in the Republic of Yemen. In February 2006 National Malaria Control Program started freely distribution of Long Lasting Impregnated Nets (LLINs) for vulnerable g... Malaria is considered as one of the main health problem in the Republic of Yemen. In February 2006 National Malaria Control Program started freely distribution of Long Lasting Impregnated Nets (LLINs) for vulnerable groups to malaria infection (pregnant women and children under 5 years). After one year of distribution, there is a need to measure the use rate among vulnerable groups and explore factors affecting their use. The aim of the study was to investigate the use rate of long lasting impregnated nets among children under five years and pregnant women in Al Moneera city and Al Koozi villages of Hodieda governorate. <strong>Methodology:</strong> Cross section study with multistage sample, Random selection of one urban and one rural locality. 768 housewives were interviewed, proportionally allocated sample according to the number of vulnerable groups in each locality. Systematic random sample to select households. <strong>Results:</strong> The use rate of LLINs for vulnerable groups was 74.3% CI (71.2 - 77.4). There was no statistically significant association between the use of LLINs and residence, also with ages of housewives, occupation, type of house, but there is strong statistically significant association between use of LLINs and having correct information about how to use and to take care of them P value < 0.001, also with educational status of housewives;P value 0.03 and educational status of fathers;P value 0.01. (84%) have correct information about how to use and take care of LLINs and the main source of information was health workers who distributed them. Only 13.4% realized pregnant women as a vulnerable group to malaria infection while about 77.9% realized children as a vulnerable group to malaria infection. The main reason of LLINs use (84.8%) was protection from nuisance of insects. <strong>Conclusion and recommendations: </strong>There is shortage in the information about the protective effect of LLINs from malaria infection and the main reason of using them is protection from nuisance of insects. There is a need to increase health awareness about the role of LLINs in malaria prevention. 展开更多
关键词 Vulnerable Groups to Malaria Infection Long-Lasting Impregnated Nets (LLINs) Use Rate Housewives Al Moneera City and Al Koozi Villages Hodieda governorate Yemen
下载PDF
上一页 1 2 171 下一页 到第
使用帮助 返回顶部