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Effect of High Temperature on Outcrossing Characteristics at the Fertility Sensitive Period of Photo-thermo Sensitive Genic Male Sterile (PTGMS) Rice Lines
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作者 王明 刘烨 +6 位作者 张海清 刘爱民 肖层林 唐荣 杨永标 蒋凌云 李雪雪 《Agricultural Science & Technology》 CAS 2017年第11期2019-2025,共7页
Four sterile lines (Peiai64S, Y58S, Guangzhan 63-2S and H638S) and the restoring line R527 were used as materials. Five temperature gradients (24, 27, 30, 33 and 36 ℃ in artificial climate chamber) and the natura... Four sterile lines (Peiai64S, Y58S, Guangzhan 63-2S and H638S) and the restoring line R527 were used as materials. Five temperature gradients (24, 27, 30, 33 and 36 ℃ in artificial climate chamber) and the natural temperature (as control) were treated to the four sterile lines for 6 d in the fertility sensitive period of heading to flowering stage, respectively, to study the effects of temperature on physiological biochemical characteristics of young panicles and outcrossing characteristics. The results showed that the percentages of exerted stigma of Peiai 64S and Y58S were the highest at 27 ℃, which were 86.81% and 86.06%, respectively, while the percentages of exerted stigma of Guangzhan 63-2S and H638S were the highest at 24 ℃, which were 76.24% and 81.76%, respectively; the stigma viability of Peiai 64S, Y58S, Guangzhan 63-2S and H638S were the best at 24 ℃, which were 1.96, 2.12, 1.74 and 1.94, respectively; the outcrossing rates of Peiai 64S, Guangzhan 63-2S and H638S were the highest at 24 ℃, which were 58.87%, 54.22% and 50.50%, respectively, while the outcrossing rate of Y58S was the highest at 27 ℃, which was 58.96%; and the contents of peroxidase (POD) of the four sterile lines increased significantly at 33 ℃ compared with the control, while the contents of malondialdehyde (MDA) and proline increased significantly at 36 ℃ compared with the control. There were differences in temperature sensitivity between the male sterile lines, and the 24 ℃ treatment during the sensitive period was the best for the fertility sensitive period of Peiai 64S, while 27 ℃ was the best temperature for Y58S, Gangzhan 63-2S and H638S. 展开更多
关键词 RICE Photo-thermo sensitive male sterile line Fertility sensitive period Temperature Outcrossing characteristics Physiological and biochemical characteristics
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Minimization of Electric Power Losses on 132 kV and 220 kV Uganda Electricity Transmission Lines
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作者 Ounyesiga Living Stephen Ndubuisi Nnamchi +2 位作者 Kelechi John Ukagwu Abubakar Abdulkarim Zaid Oluwadurotimi Jagun 《Energy and Power Engineering》 CAS 2023年第2期127-150,共24页
The classical minimization of power losses in transmission lines is dominated by artificial intelligence techniques, which do not guarantee global optimum amidst local minima. Revolutionary and evolutionary techniques... The classical minimization of power losses in transmission lines is dominated by artificial intelligence techniques, which do not guarantee global optimum amidst local minima. Revolutionary and evolutionary techniques are encumbered with sophisticated transformations, which weaken the techniques. Power loss minimization is crucial to the efficient design and operation of power transmission lines. Minimization of losses is one way to meet steady grid supply, especially at peak demand. Thus, this paper has presented a gradient technique to obtain optimal variables and values from the power loss model, which efficiently minimizes power losses by modifying the traditional power loss model that combines Ohm and Corona losses. Optimality tests showed that the unmodified model does not support the minimization of power losses on transmission lines as the Hessian matrix portrayed the maximization of power losses. However, the modified model is consistent with the gradient method of optimization, which yielded optimum variables and values from the power loss model developed in this study. The unmodified (modified) models for Bujagali-Kawanda 220 kV and Masaka West-Mbarara North 132 kV transmission lines in Uganda showed maximum power losses of 0.406 (0.391) and 0.452 (0.446) kW/km/phase respectively. These results indicate that the modified model is superior to the unmodified model in minimizing power losses in the transmission lines and should be implemented for the efficient design and operation of power transmission lines within and outside Uganda for the same transmission voltages. 展开更多
关键词 MinIMIZATION Power losses Transmission lines Corona and Ohms losses Transmission Model
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The Analysis on the Temporal and Spatial Variation of Strong Precipitation Caused Flood and Agricultural Disaster Loss in Huaihe River Basin of Anhui Province during Meiyu Period of 2007 被引量:1
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作者 YU Jia-cheng1,WU Chang-chun1,HUANG Xiao-yan1,HE Yong-qing1,YU Yang2,WANG Sheng2,GUO Xiu-yun2,WANG Hua3 1.Anhui Agricultural University,Hefei 230036,China 2.Anhui Meteorological Bureau,Hefei 230061,China 3.Anhui Civil Affairs Bureau,Hefei 230061,China 《Meteorological and Environmental Research》 CAS 2011年第7期87-90,共4页
[Objective] The research aimed to analyze temporal and spatial variation of strong precipitation caused flood and agricultural disaster loss in Huaihe River basin of Anhui Province during Meiyu period of 2007.[Method]... [Objective] The research aimed to analyze temporal and spatial variation of strong precipitation caused flood and agricultural disaster loss in Huaihe River basin of Anhui Province during Meiyu period of 2007.[Method] On the basis of rainfalls of each station in Huaihe River basin of Anhui,rainfall data during Meiyu period of 2007 and flood disaster data in the same period,the temporal and spatial distribution characteristics of strong precipitation caused flood during Meiyu period of 2007 and its harm on agriculture were analyzed.The variation rule,distribution characteristics of strong precipitation during Meiyu period in Huaihe River basin of Anhui and its relationship with agricultural disaster loss were discussed.[Result] During Meiyu period of 2007 in Huaihe River basin of Anhui,the rainstorm was more,and the rainfall was large.The precipitation variation showed 'three-peak' trend.Rainfall in Huaihe River basin during Meiyu period of 2007 was greatly more than that homochronously in Yangtze River basin.The rain area over 400.0 mm during Meiyu period mainly located in Huaihe River basin,and the rain area over 600.0 mm mainly located from area along Huaihe River to central Huaibei.The rainfall during Meiyu period gradually decreased toward south and north by the north bank of Huaihe River as the symmetry axis.The rainfall in area along Huaihe River showed wavy distribution in east-west direction.The flood disaster loss index and disaster area of crops in Huaihe River basin of Anhui both increased as rainfall in Meiyu period.[Conclusion] The research provided theoretical basis for flood prevention,disaster reduction and agricultural flood-avoiding development in Huaihe River basin. 展开更多
关键词 Huaihe River basin of Anhui Province Meiyu period of 2007 Strong precipitation caused flood Temporal and spatial distribution Agricultural disaster loss Characteristic analysis China
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The Difference of the Copy Number Variation and Loss of Heterozygosity of Human Lung Large Cell Cancer Cell Line with Different Metastatic Potential
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作者 Bin HU Xiaoming QIU Ting WANG Yu FAN Li MA Jun CHEN Sen WEI Zhigang LI Hongyu LIU Haisu WAN Zhihao WU Qinghua ZHOU 《中国肺癌杂志》 CAS 2009年第6期512-514,共3页
Background and Objective It has been proven that copy number gain/or loss (copy number variation CNV) in uences gene expression and result in phenotypic variation by
关键词 肺癌 癌细胞 CNV 治疗 疗效
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Experimental Study of Current Loss of Stainless Steel Magnetically Insulated Transmission Line with Current Density at MA/cm Level 被引量:2
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作者 吴撼宇 曾正中 +1 位作者 王亮平 郭宁 《Plasma Science and Technology》 SCIE EI CAS CSCD 2014年第6期625-628,共4页
A magnetically insulated transmission line (MITL) is used to transmit high power electric pulses in large pulse power systems. However, current loss is unavoidable, especially when the current density is up to 1 MA/... A magnetically insulated transmission line (MITL) is used to transmit high power electric pulses in large pulse power systems. However, current loss is unavoidable, especially when the current density is up to 1 MA/cm. In the paper, the current loss of an MITL made of stainless steel, which is usually used in large pulse power generators, is experimentally studied, and possible mechanisms to explain the current loss of the MITL are analyzed and discussed. From the experimental results, the relationship between loss current density and input current density follows approximately a power law. The loss is also related to the configuration of the MITL. 展开更多
关键词 magnetically insulated transmission line current loss current density ION
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Flood risk assessment of check dams in the Wangmaogou watershed on the Loess Plateau of China
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作者 GAO Ze-chao SHI Peng +4 位作者 LI Zhan-bin LI Peng BAI Lu-lu JIA Yi-li CUI Lin-zhou 《Journal of Mountain Science》 SCIE CSCD 2023年第12期3631-3647,共17页
Check dams have been widely used in China’s Loess Plateau region due to their effectiveness in erosion and flood control.However,the safety and stability of the check dam decrease with the operation process,which inc... Check dams have been widely used in China’s Loess Plateau region due to their effectiveness in erosion and flood control.However,the safety and stability of the check dam decrease with the operation process,which increases the probability of dam failure during flood events and threatens local residents’ life and property.Thus,this study simulated flood process of the check dam failure in the Wangmaogou watershed in Yulin City,Shaanxi Province,China,calculated different types of inundation losses based on the flood inundation area within the watershed,and determined the number of key flood protection check dams by classifying the flood risk levels of the check dams.The results showed that 5 dams in the watershed were subject to overtopping during different rainfall return periods,which was related to their flood discharge capacity.Dam failure flood process showed a rapid growth trend followed by slow decrease,and the time of flood peak advanced with increase in the return period.After harmonization of evaluation scales,the magnitude of flood inundation losses can be ranked as:economic losses(212.409 million yuan) > life losses(10.368 million yuan) > ecological losses(6.433 million yuan).The risk value for both individual dams and the whole dam system decreases as the return period increases.The number of key flood protection check dams in the Wangmaogou watershed was 2,3,3,3,4,and 5 for floods with return periods of 10,20,30,50,100,and 200 years,respectively.The results provided a theoretical basis for the safe operation and risk evaluation of check dams in the Loess Plateau Hills watershed. 展开更多
关键词 Check dam Return period Flood control risk Dam failure inundation loss
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Energy Loss Analysis of Distributed Rooftop Photovoltaics in Industrial Parks
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作者 Yu Xiao Kai Li +2 位作者 HongqiaoHuang Haibo Tan Hua Li 《Energy Engineering》 EI 2023年第2期511-527,共17页
The analysis of the loss of distributed photovoltaic power generation systems involves the interests of energy users,energy-saving service companies,and power grid companies,so it has always been the focus of the indu... The analysis of the loss of distributed photovoltaic power generation systems involves the interests of energy users,energy-saving service companies,and power grid companies,so it has always been the focus of the industry and society in some manner or another.However,the related analysis for an actual case that considers different cooperative corporations’benefits is lacking in the presently available literature.This paper takes the distributed rooftop photovoltaic power generation project in an industrial park as the object,studies the analysis and calculation methods of line loss and transformer loss,analyzes the change of transformer loss under different temperatures and different load rates,and compares the data and trend of electricity consumption and power generation in industrial parks before and after the photovoltaic operation.This paper explores and practices the analysis method of the operating loss of distributed photovoltaic power generation and provides an essential reference for the benefit analysis and investment cost estimation of distributed photovoltaic power generation systems in industrial parks.The analyzed results reveal that the change loss is stable after the photovoltaic is connected,and there is no additional transformer loss.And before and after the photovoltaic system installation,there was no significant change in the total monthly data difference between the total meter and the sub-meter. 展开更多
关键词 Distributed photovoltaic generation line loss transformer loss power generation
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Spatial distribution and driving factors of sediment net nitrogen mineralization in riparian zone of the Three Gorges Reservoir
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作者 JIA Kai-tao HE Li-ping +4 位作者 WANG Ke-hong YU Zhi-guo LIANG Li-jiao YU Zhuo-lin LIN Jun-jie 《Journal of Mountain Science》 SCIE CSCD 2023年第2期381-390,共10页
Inorganic nitrogen(N)loss through sediment N mineralization is important for eutrophication surrounding riparian zone.Sediment physicochemical properties have been changed at water-level elevation in riparian zone of ... Inorganic nitrogen(N)loss through sediment N mineralization is important for eutrophication surrounding riparian zone.Sediment physicochemical properties have been changed at water-level elevation in riparian zone of the Three Gorges Reservoir(TGR)due to differences in hydrological stress and human activity intensity.However,spatial distribution and driving factor of net N mineralization rate(Nmin)and its temperature sensitivity(Q10)based on the changes in sediment physicochemical properties are still unclear at waterlevel elevation in the riparian zone.A total of 132 sediment samples in the riparian zone were collected including 11 transections and 12 water-level elevations on basin scale of the TGR during drying period,to conduct a 28-day incubation at 15℃,22℃,29℃and 36℃.Nmin,total N(TN)and substrate quality(SQ)increased with water-level elevation,while Q10 showed an opposite trend(P<0.001).Results of the structural equation model showed that water-level elevation had direct positive effects on TN and SQ(P<0.01).In addition,TN was the major factor that had a direct positive effect on Nmin,and SQ was the crucial factor that had a direct negative effect on Q10(P<0.001).In conclusion,increases in TN and SQ were major driving factors of Nmin and its Q10 at water-level elevation,respectively,in riparian zone of the TGR during drying period. 展开更多
关键词 inorganic nitrogen loss Sediment physicochemical properties Drying period Substrate quality Net nitrogen mineralization rate Temperature sensitivity
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ANTIPLANE PROBLEMS OF PERIODICAL RIGID LINE INCLUSIONS BETWEEN DISSIMILAR ANISOTROPIC MATERIALS 被引量:1
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作者 LIU You-wen(刘又文) 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2001年第10期1149-1154,共6页
The antiplane shear problems of periodical rigid line inclusions between dissimilar anisotropic materials are dealt with. By using the complex variable method, the closed form solutions are obtained. The stress distri... The antiplane shear problems of periodical rigid line inclusions between dissimilar anisotropic materials are dealt with. By using the complex variable method, the closed form solutions are obtained. The stress distribution in the immediate vicinity of the rigid line is examined. The corresponding formulation between dissimilar isotropic materials and in homogeneous anisotropic medium can be derived from the special cases of those in the present paper, and the limit conditions are in agreement with the previously known results. 展开更多
关键词 anisotropic materials interface fracture periodical rigid line inclusions antiplane shear
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Link Budget Design for RF Line-of-Sight via Theoretical Propagation Prediction 被引量:1
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作者 Anwar H. Ibrahim Mohammed F. Alsharekh +2 位作者 Mohammed S. Almanee Abdulrahman S. Al-Turki Muhammed Islam 《International Journal of Communications, Network and System Sciences》 2019年第1期11-17,共7页
Line-of-sight (LOS) link planning condition has been observed to have effects on the atmospheric factor which cause crucial signal loss. The main objective of the planning was to improve a set of a link using point to... Line-of-sight (LOS) link planning condition has been observed to have effects on the atmospheric factor which cause crucial signal loss. The main objective of the planning was to improve a set of a link using point to point condition to assist the performance in emerging its strategy for handling the fixed WLAN service. The purpose of this paper is to provide a quick description of various propagation loss mechanisms on Link Budget Tool (LBT). LBT is customized to create point to point link for local area network (LAN) through radio frequency range operating between 2.400 GHz and 5.800 GHz. This software is able to define the effect of signal loss and expected performances according to the distances between link propagation conditions based on a number of system parameters. 展开更多
关键词 Path loss (PL) line of SIGHT (LOS) Microwave LinK BUDGET (MLB) LinK Planning (LP)
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Distortionless Lossy Transmission Lines Terminated by in Series Connected <i>RCL</i>-Loads 被引量:1
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作者 Vasil G. Angelov Marin Hristov 《Circuits and Systems》 2011年第4期297-310,共14页
The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutr... The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutral equation is reduced. Sufficient conditions for the existence and uniqueness of periodic regimes are formulated. The proof is based on the finding out of suitable operator whose fixed point is a periodic solution of the neutral equation. The method has a good rate of convergence of the successive approximations even for high frequencies. 展开更多
关键词 lossY Transmission line RCL-Nonlinear Loads Fixed POinT periodIC Solution
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ANALYSIS OF OPEN MICROSTRIP STRUCTURES BY USING DIAKOPTIC METHOD OF LINES COMBINED WITH PERIODIC BOUNDARY CONDITIONS
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作者 Zhu Hanqing Fang Dagang Long Yi(Department of Electronic Engineering, Nanjing University of Science and Technology, Nanjing 210094) 《Journal of Electronics(China)》 1998年第1期90-96,共7页
This paper presents the analysis of open microstrip structures by using diakoptic method of lines (ML) combined with periodic boundary conditions (PBC). The parameters of microstrip patch are obtained from patch curre... This paper presents the analysis of open microstrip structures by using diakoptic method of lines (ML) combined with periodic boundary conditions (PBC). The parameters of microstrip patch are obtained from patch current excited by plane wave. Impedance matrix elements are computed by using fast Fourier transform(FFT), and reduced equation is solved by using diakoptic technique. Consequently, the computing time is reduced significantly. The convergence property of simulating open structure by using PBC and the comparison of the computer time between using PBC and usual absorbing boundary condition (ABC) show the validity of the method proposed in this paper. Finally, the resonant frequency of a microstrip patch is computed. The numerical results obtained are in good agreement with those published. 展开更多
关键词 OPEN MICROSTRIP structures Method of lineS periodIC boundary conditions Fast FOURIER TRANSFORM Diakoptic technique
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Investigation on current loss of high-power vacuum transmission lines with coaxial-disk transitions by particle-in-cell simulations
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作者 Wei LUO Jianwei ZHANG +4 位作者 Yongdong LI Hongguang WANG Chunliang LIU Pengfei ZHANG Fan GUO 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第11期177-184,共8页
Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines(MITLs),resulting in disturbed electron flow and non-negligible current los... Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines(MITLs),resulting in disturbed electron flow and non-negligible current loss.In this paper,3 D particle-in-cell simulations are conducted with UNPIC-3 d to investigate the current loss mechanism and the influence of the input parameters of the coaxial-disk transition on current loss in an MITL system.The results reveal that the magnetic field non-uniformity causes major current loss in the MITL after the coaxialdisk transition,and the non-uniformity decreases with the distance away from the transition.The uniformity of the magnetic field is improved when increasing the number of feed lines of a linear transformer driver-based accelerator with coaxial-disk transitions.The number of input feed lines should be no less than four in the azimuthal distribution to obtain acceptable uniformity of the magnetic field.To make the ratio of the current loss to the total current of the accelerator less than 2%at peak anode current,the ratio of the current in each feed line to the total current should be no less than 8%. 展开更多
关键词 magnetically insulated transmission line coaxial-disk transition current loss
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The Effect of Photon Flux Density and Lighting Period on Growth,Flowering,Powdery Mildew and Water Relations of Miniature Roses 被引量:1
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作者 Leiv M.Mortensen 《American Journal of Plant Sciences》 2014年第13期1813-1818,共6页
Miniature roses (Rosa sp.) were grown at 100 and 150 μmol m-2·s-1 photon flux densities (PFD) with 16, 20 and 24 h·day-1 lighting periods (LP) in a greenhouse compartment in midwinter at latitude 59° n... Miniature roses (Rosa sp.) were grown at 100 and 150 μmol m-2·s-1 photon flux densities (PFD) with 16, 20 and 24 h·day-1 lighting periods (LP) in a greenhouse compartment in midwinter at latitude 59° north. The study included 10 different treatments and six rose cultivars, altogether 900 plants. The 16 and 20 h LP were applied with or without a dark period of 8 and 4 h·day-1, respectively, by timing the LP in relation to daylight that lasted for 7 - 8 h. Number of days until flowering decreased with an increase in PFD and in LP up to 24 day-1 and was unaffected by the timing of the 16 and 20 h·day-1 LP. Number of flowers and plant dry weight increased 20% to 30% by increasing the PFD. Plant dry weight increased by increasing the LP from 16 to 20 h·day-1 (about 25%), but no effect was found with a further increase to 24 h·day-1. Mean growth rate until flowering increased 30% to 40% by increasing the PFD or by increasing the LP from 16 to 20 h day-1, while little effect was found by a further increase to 24 h·day-1. Increasing the photosynthetic active radiation (PAR) by increasing the LP from 16 to 20 h·day-1 increased the growth rate more than increasing the PFD did. Three of the cultivars were tested for water loss after the detachment of some leaves. Leaves that had developed without a dark period showed a considerably higher water loss than the treatments that included a dark period of 4 or 8 h·day-1. The keeping quality at indoor conditions, however, was unaffected by the treatment due to sufficient watering. Powdery mildew developed significantly more on plants grown with a dark period of 8 h as compared with the other treatments. It was concluded that 20 h·day-1 LP including a dark period of 4 h·day-1 and a PFD of at least 150 μmol·m-2·s-1 should be applied to miniature roses during the winter months in order to effectively produce miniature pot roses with a high quality. 展开更多
关键词 FLOWERinG GROWTH Keeping Life Leaf Water loss Lighting period Miniature Rose Photon Flux Density(PFD) Photosynthetic Active Radiation(PAR) Powdery Mildew
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Semi-Markovian Model of Two-Line Queuing System with Losses 被引量:2
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作者 Yuriy E. Obzherin 《Intelligent Information Management》 2016年第2期17-26,共10页
In the present paper, to build model of two-line queuing system with losses GI/G/2/0, the approach introduced by V.S. Korolyuk and A.F. Turbin, is used. It is based on application of the theory of semi-Markov processe... In the present paper, to build model of two-line queuing system with losses GI/G/2/0, the approach introduced by V.S. Korolyuk and A.F. Turbin, is used. It is based on application of the theory of semi-Markov processes with arbitrary phase space of states. This approach allows us to omit some restrictions. The stationary characteristics of the system have been defined, assuming that the incoming flow of requests and their service times have distributions of general form. The particular cases of the system were considered. The used approach can be useful for modeling systems of various purposes. 展开更多
关键词 Two-line Queuing System with losses Semi-Markov Process Stationary Distribution of Embedded Markov Chain Stationary Characteristics of System
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On-line Monitoring of Insulation Dielectric Loss Factor Based on Balance Principle
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作者 Tianxiang CHEN Zhenhua SHAO +1 位作者 Shaozhen QIN Hong TIAN 《电力系统自动化》 EI CSCD 北大核心 2013年第21期180-183,共4页
关键词 介质损耗因数 平衡原则 在线监测 绝缘 相位误差 高精确度 电流传感器 位移传感器
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On-Line Suppression of Periodic Noises in Evoked Potentials
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作者 周卫 袁孝如 《The Journal of Biomedical Research》 CAS 1994年第1期1-4,共4页
Under clinical conditions,the major components of noises in human evoked potentialsare periodic impulses,such as power interferences, system oscillations. Reducing their effects by analogfilter is inevitably associate... Under clinical conditions,the major components of noises in human evoked potentialsare periodic impulses,such as power interferences, system oscillations. Reducing their effects by analogfilter is inevitably associated with the distortions of the signal of interest.In this paper,a new approachto suppress periodic noises is presented using time-domain operators which are applied on the individualdigitized responses before averaging.A new algorithm for real time processing is developed.The effectiveness of the algorithm in dealing with simulated as well as actual evoked responses is demonstrated.The results show that this algorithm has good performance in periodic noise suppression and has zerophase shift, thus it is very suitable to be implemented on biomedical instrumentations used inclinical setups. 展开更多
关键词 evoked potentials on-line suppression of periodic noise
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Improved Method of Power Loss and Electric Field Calculations of HVAC Transmission Lines
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作者 DU Zhiye RUAN Jiangjun JIN Shuo HUANG Guodong ZHU Lin 《高电压技术》 EI CAS CSCD 北大核心 2013年第10期2365-2371,共7页
An improved method for calculating the corona power loss and the ground-level electric field on HVAC transmission lines induced by corona is proposed.Based on a charge simulation method combined with a method of succe... An improved method for calculating the corona power loss and the ground-level electric field on HVAC transmission lines induced by corona is proposed.Based on a charge simulation method combined with a method of successive images,the proposed method has the number and location of the simulated charges not arbitrary.When the surface electric field of a conductor exceeds the onset value,charges are emitted from corona into the space around,and the space ions and the surface charges on each sub-conductor are simulated by using the images of the other sub-conductors.The displacements of the space ions are calculated at every time step during corona periods in both the positive and the negative half cycles.Several examples are calculated by using the proposed method,and the calculated electric field at the ground level and the corona power loss agree well with previous measurements.The results show that simulating 12 charges in each conductor during 600 time steps in one cycle takes less time while guarantees the accuracy.The corona discharge from a 220 kV transmission line enhances slightly(less than 2%) the electric field at the ground level,but this effect is little from a 500 kV line.The improved method is a good compromise between the time cost and the accuracy of calculation. 展开更多
关键词 位移计算 表面电场 功率损耗 输电线路 HVAC 模拟电荷法 500千伏线路 电晕放电
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基于K-Means聚类和Boosting算法的配电网线损计算方法
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作者 马芳 张晨晖 《通信电源技术》 2024年第1期1-3,共3页
传统线损计算方法所需电气参数较多且计算过程烦琐,导致配电网线损计算结果精度较低,因此提出了一种基于K-Means聚类和Boosting算法的配电网线损计算方法。先采用K-Means聚类算法挖掘配电网的线路负荷有功电量、线路负荷无功电量、线路... 传统线损计算方法所需电气参数较多且计算过程烦琐,导致配电网线损计算结果精度较低,因此提出了一种基于K-Means聚类和Boosting算法的配电网线损计算方法。先采用K-Means聚类算法挖掘配电网的线路负荷有功电量、线路负荷无功电量、线路长度及线路负载率等电气特征指标,再将电气特征指标作为Boosting算法线损预测模型的输入数据,经过模型训练完成配电网线损的预测计算。实验结果表明,该设计方法的线损计算值与真实值之间的误差仅为4.27%,具有较高的配电网线损计算精度。 展开更多
关键词 K-MEANS聚类 BOOSTinG算法 配电网线损 线损计算
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Analysis and Application of the Synthetic Relative Measuring Method in On-Line Monitoring for Capacitive Equipment in Power Systems
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作者 Qing Guo Li-Jun Qin Hua-Wei Jin 《Journal of Electronic Science and Technology》 CAS 2011年第3期270-277,共8页
On-line measurement for dielectric loss angle can effectively monitor the insulation condition of capacitive equipment in power systems. Synthetic relative measuring methods not only markedly overcome the shortcomings... On-line measurement for dielectric loss angle can effectively monitor the insulation condition of capacitive equipment in power systems. Synthetic relative measuring methods not only markedly overcome the shortcomings of traditional absolute measuring methods but also greatly improve the accuracy of dielectric loss angle measurement. However, synthetic relative measuring methods based on two or three pieces of capacitive equipment do not have the characteristic of generality. In this paper, a principle of synthetic relative measuring method is presented. The example of application for synthetic relative methods based on three and four pieces of capacitive equipment running in the same phase is taken to present the failure judgment matrices for N pieces of equipment. According to these matrices, the fault condition of N pieces of capacitive equipment can be watched, which is more general. Then some problems needing to be concerned along with two diagnostic methods used in diagnostic system are introduced. Finally, two programmable flow charts for the two methods are given and corresponding examples demonstrate their feasibility in practice. 展开更多
关键词 index Terms-Capacitive equipment dielectric loss angle on-line monitoring synthetic relative measuring method failure judgment matrix.
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