The quality change of cultivated land resources requires the scientific deployment of monitoring areas.In this study,Yuzhou City is taken as an example to divide the quality monitoring control areas through the study ...The quality change of cultivated land resources requires the scientific deployment of monitoring areas.In this study,Yuzhou City is taken as an example to divide the quality monitoring control areas through the study of natural quality,utilization level,income level,and utilization characteristics,etc.Compared with the traditional administrative unit division or cultivated land quality division method,the regional homogeneity of this study is stronger,and there are quality differences between regions.It provides precondition and precision guarantee for the monitoring of cultivated land quality.展开更多
Based on the sheet, scanning electron microscope and high pressure mercury analysis method, this paper takes Jiyuan oilfield-Ma Jia mountain district 4 5 sandstone reservoir as the research object, from the reservoir ...Based on the sheet, scanning electron microscope and high pressure mercury analysis method, this paper takes Jiyuan oilfield-Ma Jia mountain district 4 5 sandstone reservoir as the research object, from the reservoir petrology, pore type and porosity, permeability, the system analyzed the reservoir characteristics and its control factors. The results show that the sandstone in the 4 5 section of Baoziwan-Majiashan area of Jiyuan oilfield is fine in size and high in filling content. The pore types were dominated by intergranular pores and dissolved pores, with a low face rate. The reservoir property is relatively poor, with mean porosity of 11.11% and mean permeability of 1.16 × 10<sup>−</sup><sup>3</sup> µm<sup>2</sup>. In the low porous, low otonic background, the development of relatively high pore hypertonic areas. Compaction and cementation should play a destructive role in reservoir properties, and dissolution should play a positive role in reservoir properties. Compaction adjusts the migration of clay minerals and miscellaneous bases in the original sediment in the study area, greatly reducing the porosity and permeability of the reservoir;the development of the cement cement, carbonate cementation and some quartz secondary compounds reduces the storage space;the dissolution effect, especially the secondary dissolution pores of the reservoir, which obviously improves the properties of the reservoir.展开更多
The situation of occurrence and hazards by Tetranychus truncatus and T. urticae on corns in test garden of Agricultural College of Yanbian University were narrated in detail. The characteristics of distribution and da...The situation of occurrence and hazards by Tetranychus truncatus and T. urticae on corns in test garden of Agricultural College of Yanbian University were narrated in detail. The characteristics of distribution and damage by T. truncates and T. urticae, morphological characteristics, the rule of currencies and its relation- ship with environment were summarized, and the methods of comprehensive treat- ment were put out, which could effectively control the hazard degree of T. truncates and T. urticae on corns.展开更多
Taking state-controlled section of Xuzhou Peiyan river as an example,the current water quality was monitored,and the cause of over water quality standard was analyzed.The results showed that the pollutants of Peiyan r...Taking state-controlled section of Xuzhou Peiyan river as an example,the current water quality was monitored,and the cause of over water quality standard was analyzed.The results showed that the pollutants of Peiyan river were mainly from the urban river segment,and the immediate cause of over standard was tributary pollutants in urban river segment with the runoff into rivers.So we should strengthen the maintenance of drainage control and gate-han,accelerate the construction of urban wastewater treatment facilities and supporting pipe network,promote rural decentralized sewage treatment,prevent and control livestock and poultry pollution,pesticides and fertilizers pollution,and intercept non-point source pollution by using eco-technology.展开更多
In order to control the air pollution caused by ships and improve ambient air quality,China set up three domestic emission control areas(DECAs)in 2015 in the Pearl River Delta,the Yangtze River Delta and Bohai Rim(Bei...In order to control the air pollution caused by ships and improve ambient air quality,China set up three domestic emission control areas(DECAs)in 2015 in the Pearl River Delta,the Yangtze River Delta and Bohai Rim(Beijing-Tianjin-Hebei)waters.In order to meet the emission requirements established at the 70th meeting of the Marine Environmental Protection Committee(MEPC),China intends to apply for the establishment of three international Emission Control Area(ECA)in 2030 for these DECAs.This paper discusses existing technologies to reduce emissions of nitrogen oxides(NOx)and sulphur oxides(SOx),and examines the abatement costs for the shipping industry in the year 2030 to comply with this action.Based on an examination of the literature and data collected for this study,four traditional alternatives,low-sulphur fuel,sulphur scrubbers/exhaust gas cleaning systems(EGCS),selective catalytic reduction(SCR),and exhaust gas recirculation,are analyzed.The analysis finds that switching to low-sulphur fuel is the best technical solution for SOx emission reduction,and the installation of SCR is the best technology for reducing nitrogen.In addition to traditional emission reduction technologies,the use of shore power facilities and liquefied natural gas(LNG),two alternatives welcomed by China’s green shipping industry,are also considered in this paper.The expected average abatement cost of these alternatives in the year 2030 are USD 2.866 billion,0.324 billion,1.071 billion,0.402 billion,0.232 billion and 0.34 billion,respectively.展开更多
In this study,two integrated game models are developed to explore the possible economic and environmental consequences of Emission control areas(ECA)regulations.Moreover,the analytical solutions compared with a benchm...In this study,two integrated game models are developed to explore the possible economic and environmental consequences of Emission control areas(ECA)regulations.Moreover,the analytical solutions compared with a benchmark case are derived.We find that vessel speed and SO_(2)emissions will decrease under the ECA regulations.However,shipping company’s level of competition has no effect on the equivalent speed.The equivalent freight volume to be reduced or increased is determined by the additional operational cost per voyage due to ECA regulations.Numerical study and sensitivity analysis reveal that the vessel speed and SO_(2)emission reduction are very sensitive to the inventory costs of intransit cargo.Furthermore,if low-sulphur marine gas oil is used throughout the voyage,the SO_(2)emission reduction may be greater than 80%,with a low impact on the shipping company’s profit.Thus,considering the environmental effects,much stricter limits can be set in the future.展开更多
Wide area damping controller(WADC) is usually utilized to damp interarea low frequency oscillation in power system. However, conventional WADC design method neglects the influence of signal transmission delay and damp...Wide area damping controller(WADC) is usually utilized to damp interarea low frequency oscillation in power system. However, conventional WADC design method neglects the influence of signal transmission delay and damping performance of WADC designed by the conventional method may deteriorate or even has no effect when signal transmission delay is beyond delay margin, an index that denotes delay endurance degree of power system. Therefore, a new design method for WADC under the condition of expected damping factor and required signal transmission delay is presented in this work. An improved delay margin with less conservatism is derived by adopting a new Lyapunov-Krasovskii function and more compact bounding technique on the derivative of Lyapunov-Krasovskii functional. The improved delay margin, which constructs the correlation of damping factor and signal transmission delay, can be used to design WADC. WADC designed by the proposed method can ensure that power system satisfies expected damping factor when WADC input signal is delayed within delay margin. Satisfactory test results demonstrate the effectiveness of the proposed method.展开更多
This paper reviews the research work done on the Reliability Analysis of Controller Area Network (CAN) based systems. During the last couple of decades, real-time researchers have extended schedulability analysis to a...This paper reviews the research work done on the Reliability Analysis of Controller Area Network (CAN) based systems. During the last couple of decades, real-time researchers have extended schedulability analysis to a mature technique which for nontrivial systems can be used to determine whether a set of tasks executing on a single CPU or in a distributed system will meet their deadlines or not [1-3]. The main focus of the real-time research community is on hard real-time systems, and the essence of analyzing such systems is to investigate if deadlines are met in a worst case scenario. Whether this worst case actually will occur during execution, or if it is likely to occur, is not normally considered. Reliability modeling, on the other hand, involves study of fault models, characterization of distribution functions of faults and development of methods and tools for composing these distributions and models in estimating an overall reliability figure for the system [4]. This paper presents the research work done on reliability analysis developed with a focus on Controller-Area-Network-based automotive systems.展开更多
This paper is devoted to investigate the robust H∞sliding mode load frequency control(SMLFC) of multi-area power system with time delay. By taking into account stochastic disturbances induced by the integration of re...This paper is devoted to investigate the robust H∞sliding mode load frequency control(SMLFC) of multi-area power system with time delay. By taking into account stochastic disturbances induced by the integration of renewable energies,a new sliding surface function is constructed to guarantee the fast response and robust performance, then the sliding mode control law is designed to guarantee the reach ability of the sliding surface in a finite-time interval. The sufficient robust frequency stabilization result for multi-area power system with time delay is presented in terms of linear matrix inequalities(LMIs). Finally,a two-area power system is provided to illustrate the usefulness and effectiveness of the obtained results.展开更多
The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator cont...The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator control scheme. To this end, we consider a nonlinear interconnected model for multiarea power systems which also include uncertainties and timevarying communication delays. The design procedure is formulated using semi-definite programming and linear matrix inequality(LMI) method. The solution of the proposed LMIs returns necessary parameters for the tracking controllers such that the impact of model uncertainty and load disturbances are minimized. The proposed controllers are capable of receiving all or part of subsystems information, whereas the outputs of each controller are local. These controllers are designed such that the resilient stability of the overall closed-loop system is guaranteed. Simulation results are provided to verify the effectiveness of the proposed scheme. Simulation results quantify that the distributed(and decentralized) controlled system behaves well in presence of large parameter perturbations and random disturbances on the power system.展开更多
Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out ...Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations.Wide area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote location.Communication failure is one of the disastrous phenomena in a communication channel.In this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area mode.The proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is lost.The time delay is an unwanted phenomenon that degrades the performance of the controllers.The unified Smith predictor approach is used to design a Hm controller to handle the time delay.Kundur's two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed controller.From the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.展开更多
The Controller Area Network (CAN) is a well established control network for automotive and automation control applications. Time-Triggered Controller Area Network (TTCAN) is a recent development which introduces a ses...The Controller Area Network (CAN) is a well established control network for automotive and automation control applications. Time-Triggered Controller Area Network (TTCAN) is a recent development which introduces a session layer,for message scheduling,to the existing CAN standard,which is a two layer standard comprising of a physical layer and a data link layer. TTCAN facilitates network communication in a time-triggered fashion,by introducing a Time Division Multiple Access style communication scheme. This allows deterministic network behavior,where maximum message latency times can be quantified and guaranteed. In order to solve the problem of determinate time latency and synchronization among several districted units in one auto panel CAN systems,this paper proposed a prototype design implementation for a shared-clock scheduler based on PIC18F458 MCU. This leads to improved CAN system performance and avoid the latency jitters and guarantee a deterministic communication pattern on the bus. The real runtime performance is satisfied.展开更多
Based on the production data of a large number of surface drainage wells in the Huainan mining area,the present study shows that four types of typical production characteristics for relieved methane wells are recogniz...Based on the production data of a large number of surface drainage wells in the Huainan mining area,the present study shows that four types of typical production characteristics for relieved methane wells are recognized,of which the stable type for production and gas concentration is the most dominate,as determined by a comprehensive study on the volume and concentration of drained gases, as well as the stress changes of rocks influenced by mining.Some influence factors for the productive differences of the drainage wells were also been discussed.The results indicate that protective coal-seam mining has a significant effect on overlying strata,which promotes the development of pores and fractures of coal reservoirs for methane desorption and migration;however,the production and the stability of drainage wells are affected by deformation and damage of the overlying strata.The second distribution of strata stress is caused by mining engineering,and if the stress load is larger than the carrying capacity of the extraction well,the gas production would be influenced by the drainage well that has been damaged by rock movement.Furthermore,the case damage occurs first in the weak, lithologic interface by its special mechanical properties.The stability of drainage wells and the production status are also influenced by the different drilling techniques,uneven distribution of gas concentration,and combination of gob gas and methane from the protected layer.展开更多
The number of smokers in Chinese rural areas is more than 200 million, which is twice that in cities. It is very significant to carry out tobacco control interventions in rural areas. We performed this community inter...The number of smokers in Chinese rural areas is more than 200 million, which is twice that in cities. It is very significant to carry out tobacco control interventions in rural areas. We performed this community intervention study to evaluate the efficacy of village-based health education of tobacco control on the male current smoking rate in rural areas. The population of this study was the males above 15 years old from 6 villages in rural areas. The villages were randomly assigned to intervention group or control group(3 villages in each group). Self-designed smoking questionnaire was applied. The intervention group received the village-based health education of tobacco control for one year. The primary outcome measurement was the male current smoking rate. In the baseline investigation, completed surveys were returned by 814 male residents from the control group and 831 male residents from the intervention group. The male current smoking rate in the control group and the intervention group was 61.2% and 58.5%, respectively, before intervention. There was no significant difference between these two groups(P〉0.05). After one-year intervention, the current smoking rate in the intervention group(51.2%) was significantly lower than that in the control group(62.8%)(P〈0.001). Our study suggested that the village-based health education of tobacco control was effective in lowering the male current smoking rate in rural areas, which could be a suitable and feasible way for tobacco control in the Chinese rural areas.展开更多
The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Fo...The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated.Shale cores underwent laboratory testing,which included the evaluation of total organic carbon(TOC),vitrinite reflectance(Ro),whole-rock X-ray diffraction(XRD),pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM).Based on the results of natural gamma ray spectrum logging,conventional logging,imaging logging,and seismic coherence properties,the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively.The results showed that(1)layer No.4(WF2-LM4)of the Wufeng-Longmaxi Formation has a Th/U ratio<2 and a Th/K ratio of 3.5–12.Graptolites and pyrite are relatively abundant in the shale core,indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2)The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen.There is a good correlation among TOC,Ro,gas content,and brittle minerals;the fracturing property(brittleness)is 57.3%.Organic and inorganic pores are moderately developed.A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3)The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects,and it is poorly preserved.The DY2 well is located far from the Qiyueshan Fault.Large faults are absent,and upward fractures in the Longmaxi Formation are poorly developed.The well is affected by low tectonic deformation intensity,and it is well preserved.(4)The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning.The thickness of the high-quality shale interval(WF2-LM4)is relatively small,which may be an important reason for the unstable production of shale gas thus far.Based on the systematic analysis of the geological factors controlling high-yield shale gas enrichment in the Dingshan area,and the comparative analysis with the surrounding typical exploration areas,the geological understanding of marine shale gas enrichment in southern China has been improved.Therefore,this study can provide a useful reference for shale gas exploration and further development.展开更多
This paper firstly reviews the recent development in power system protection and control, with special attention paid to the wide-area and integrated protection, in order to look into future development of integration...This paper firstly reviews the recent development in power system protection and control, with special attention paid to the wide-area and integrated protection, in order to look into future development of integration of protection and control for smart grids. This paper mainly reports on the development of integrated wide area protection and control for power systems. The concept of integrated wide area protection and control is introduced, in which a hierarchical protection and control system provides the protection and control of wide area or regional power substations/ plants and their associated power network. The system is mainly divided into three levels, the local, the substation/plant and the wide area/regional protection and control. The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between the levels. One of the core elements in the system is the synchronised wide area communication network between the substations and the protection and control system, in which latest communication technology is employed. Another important player in the system is the wide area synchronized protection and control information platform, which not only enables the fusion three line of defence for power system protection and control, but also provides a perfect tool for the application of cloud computing to substations and power networks.展开更多
Analysis and study of clastic and clay minerals of surface sediments and their chemical composition in the sea area northwest of the Antarctic Peninsula enable the authors to divide this area basically into four miner...Analysis and study of clastic and clay minerals of surface sediments and their chemical composition in the sea area northwest of the Antarctic Peninsula enable the authors to divide this area basically into four mineralogical provinces : (1) the mineral ogical province of coast and island shelf of the Southern Shetland Islands, (2) the mineral ogical province of the eastern Bransfield Strait, (3) the mineral ogical province of the western Bransfield Strait, and (4) the mineral ogical province of the western Antarctic Peninsula. Finally, the relationships between the mineral distribution and geologic ,structure, material sources, glaciers, currents, and environments are briefly described.展开更多
Historically,frequent and heavy snow disaster(SD)has caused serious livestock death and casualties,resulting in a devastating impact on animal husbandry development in the Three Rivers Source Region(TRSR).From winter ...Historically,frequent and heavy snow disaster(SD)has caused serious livestock death and casualties,resulting in a devastating impact on animal husbandry development in the Three Rivers Source Region(TRSR).From winter in 2018 to spring in 2019,the largest SD occurred in this area over the past 10 years,especially in core zones of the Lancang River Source Region.Field research results show that the main causes of the major SD include weak infrastructure(i.e.,roads,communications,warm sheds,and insufficient forage reserve),low rate of domestic animals for sale before the SD,and low loss settlement rate.SD occurrence could furtherly reduce the ability of disaster prevention,mitigation and relief of disaster loss.In the future,heavily affected SD areas should improve the forecasting ability of snowfall incidents,strengthen infrastructure construction,implement grass and livestock balance strategies,optimize livestock structure,improve loss settlement rate,and develop a modern compound model of animal husbandry development model that combines breeding,slaughtering and deep processing of animal product.展开更多
A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power system...A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power systems worldwide and has led to operation of power systems closer to their stability limits and to power exchange in new patterns. These issues, as well as the on-going worldwide trend towards deregulation of the entire industry on the one hand and the increased need for accurate and better network monitoring on the other hand, force power utilities exposed to this pressure to demand new solutions for wide area monitoring, protection and control. Wide-area monitoring, protection, and control require communicating the specific-node information to a remote station but all information should be time synchronized so that to neutralize the time difference between information. It gives a complete simultaneous snap shot of the power system. The conventional system is not able to satisfy the time-synchronized requirement of power system. Phasor Measurement Unit (PMU) is enabler of time-synchronized measurement, it communicate the synchronized local information to remote station.展开更多
基金Supported by Basic Scientific Research Project of Henan Academy of Sciences(220601065)Henan Youth Science Fund Project(212300410168)。
文摘The quality change of cultivated land resources requires the scientific deployment of monitoring areas.In this study,Yuzhou City is taken as an example to divide the quality monitoring control areas through the study of natural quality,utilization level,income level,and utilization characteristics,etc.Compared with the traditional administrative unit division or cultivated land quality division method,the regional homogeneity of this study is stronger,and there are quality differences between regions.It provides precondition and precision guarantee for the monitoring of cultivated land quality.
文摘Based on the sheet, scanning electron microscope and high pressure mercury analysis method, this paper takes Jiyuan oilfield-Ma Jia mountain district 4 5 sandstone reservoir as the research object, from the reservoir petrology, pore type and porosity, permeability, the system analyzed the reservoir characteristics and its control factors. The results show that the sandstone in the 4 5 section of Baoziwan-Majiashan area of Jiyuan oilfield is fine in size and high in filling content. The pore types were dominated by intergranular pores and dissolved pores, with a low face rate. The reservoir property is relatively poor, with mean porosity of 11.11% and mean permeability of 1.16 × 10<sup>−</sup><sup>3</sup> µm<sup>2</sup>. In the low porous, low otonic background, the development of relatively high pore hypertonic areas. Compaction and cementation should play a destructive role in reservoir properties, and dissolution should play a positive role in reservoir properties. Compaction adjusts the migration of clay minerals and miscellaneous bases in the original sediment in the study area, greatly reducing the porosity and permeability of the reservoir;the development of the cement cement, carbonate cementation and some quartz secondary compounds reduces the storage space;the dissolution effect, especially the secondary dissolution pores of the reservoir, which obviously improves the properties of the reservoir.
文摘The situation of occurrence and hazards by Tetranychus truncatus and T. urticae on corns in test garden of Agricultural College of Yanbian University were narrated in detail. The characteristics of distribution and damage by T. truncates and T. urticae, morphological characteristics, the rule of currencies and its relation- ship with environment were summarized, and the methods of comprehensive treat- ment were put out, which could effectively control the hazard degree of T. truncates and T. urticae on corns.
文摘Taking state-controlled section of Xuzhou Peiyan river as an example,the current water quality was monitored,and the cause of over water quality standard was analyzed.The results showed that the pollutants of Peiyan river were mainly from the urban river segment,and the immediate cause of over standard was tributary pollutants in urban river segment with the runoff into rivers.So we should strengthen the maintenance of drainage control and gate-han,accelerate the construction of urban wastewater treatment facilities and supporting pipe network,promote rural decentralized sewage treatment,prevent and control livestock and poultry pollution,pesticides and fertilizers pollution,and intercept non-point source pollution by using eco-technology.
基金The Second National Census of Pollution Sources Mobile Source Census Technical Specifications and Organization and Implementation(2018-033-B-021)。
文摘In order to control the air pollution caused by ships and improve ambient air quality,China set up three domestic emission control areas(DECAs)in 2015 in the Pearl River Delta,the Yangtze River Delta and Bohai Rim(Beijing-Tianjin-Hebei)waters.In order to meet the emission requirements established at the 70th meeting of the Marine Environmental Protection Committee(MEPC),China intends to apply for the establishment of three international Emission Control Area(ECA)in 2030 for these DECAs.This paper discusses existing technologies to reduce emissions of nitrogen oxides(NOx)and sulphur oxides(SOx),and examines the abatement costs for the shipping industry in the year 2030 to comply with this action.Based on an examination of the literature and data collected for this study,four traditional alternatives,low-sulphur fuel,sulphur scrubbers/exhaust gas cleaning systems(EGCS),selective catalytic reduction(SCR),and exhaust gas recirculation,are analyzed.The analysis finds that switching to low-sulphur fuel is the best technical solution for SOx emission reduction,and the installation of SCR is the best technology for reducing nitrogen.In addition to traditional emission reduction technologies,the use of shore power facilities and liquefied natural gas(LNG),two alternatives welcomed by China’s green shipping industry,are also considered in this paper.The expected average abatement cost of these alternatives in the year 2030 are USD 2.866 billion,0.324 billion,1.071 billion,0.402 billion,0.232 billion and 0.34 billion,respectively.
文摘In this study,two integrated game models are developed to explore the possible economic and environmental consequences of Emission control areas(ECA)regulations.Moreover,the analytical solutions compared with a benchmark case are derived.We find that vessel speed and SO_(2)emissions will decrease under the ECA regulations.However,shipping company’s level of competition has no effect on the equivalent speed.The equivalent freight volume to be reduced or increased is determined by the additional operational cost per voyage due to ECA regulations.Numerical study and sensitivity analysis reveal that the vessel speed and SO_(2)emission reduction are very sensitive to the inventory costs of intransit cargo.Furthermore,if low-sulphur marine gas oil is used throughout the voyage,the SO_(2)emission reduction may be greater than 80%,with a low impact on the shipping company’s profit.Thus,considering the environmental effects,much stricter limits can be set in the future.
基金Project(51007042) supported by the National Natural Science Foundation of China
文摘Wide area damping controller(WADC) is usually utilized to damp interarea low frequency oscillation in power system. However, conventional WADC design method neglects the influence of signal transmission delay and damping performance of WADC designed by the conventional method may deteriorate or even has no effect when signal transmission delay is beyond delay margin, an index that denotes delay endurance degree of power system. Therefore, a new design method for WADC under the condition of expected damping factor and required signal transmission delay is presented in this work. An improved delay margin with less conservatism is derived by adopting a new Lyapunov-Krasovskii function and more compact bounding technique on the derivative of Lyapunov-Krasovskii functional. The improved delay margin, which constructs the correlation of damping factor and signal transmission delay, can be used to design WADC. WADC designed by the proposed method can ensure that power system satisfies expected damping factor when WADC input signal is delayed within delay margin. Satisfactory test results demonstrate the effectiveness of the proposed method.
文摘This paper reviews the research work done on the Reliability Analysis of Controller Area Network (CAN) based systems. During the last couple of decades, real-time researchers have extended schedulability analysis to a mature technique which for nontrivial systems can be used to determine whether a set of tasks executing on a single CPU or in a distributed system will meet their deadlines or not [1-3]. The main focus of the real-time research community is on hard real-time systems, and the essence of analyzing such systems is to investigate if deadlines are met in a worst case scenario. Whether this worst case actually will occur during execution, or if it is likely to occur, is not normally considered. Reliability modeling, on the other hand, involves study of fault models, characterization of distribution functions of faults and development of methods and tools for composing these distributions and models in estimating an overall reliability figure for the system [4]. This paper presents the research work done on reliability analysis developed with a focus on Controller-Area-Network-based automotive systems.
基金supported in part by the National Natural Science Foundation of China(61673161)the Natural Science Foundation of Jiangsu Province of China(BK20161510)+2 种基金the Fundamental Research Funds for the Central Universities of China(2017B13914)the 111 Project(B14022)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘This paper is devoted to investigate the robust H∞sliding mode load frequency control(SMLFC) of multi-area power system with time delay. By taking into account stochastic disturbances induced by the integration of renewable energies,a new sliding surface function is constructed to guarantee the fast response and robust performance, then the sliding mode control law is designed to guarantee the reach ability of the sliding surface in a finite-time interval. The sufficient robust frequency stabilization result for multi-area power system with time delay is presented in terms of linear matrix inequalities(LMIs). Finally,a two-area power system is provided to illustrate the usefulness and effectiveness of the obtained results.
文摘The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator control scheme. To this end, we consider a nonlinear interconnected model for multiarea power systems which also include uncertainties and timevarying communication delays. The design procedure is formulated using semi-definite programming and linear matrix inequality(LMI) method. The solution of the proposed LMIs returns necessary parameters for the tracking controllers such that the impact of model uncertainty and load disturbances are minimized. The proposed controllers are capable of receiving all or part of subsystems information, whereas the outputs of each controller are local. These controllers are designed such that the resilient stability of the overall closed-loop system is guaranteed. Simulation results are provided to verify the effectiveness of the proposed scheme. Simulation results quantify that the distributed(and decentralized) controlled system behaves well in presence of large parameter perturbations and random disturbances on the power system.
基金support by the Central Power Research Institute,India(CPRI/RD/RSOP/GRANT/2015)
文摘Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations.Wide area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote location.Communication failure is one of the disastrous phenomena in a communication channel.In this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area mode.The proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is lost.The time delay is an unwanted phenomenon that degrades the performance of the controllers.The unified Smith predictor approach is used to design a Hm controller to handle the time delay.Kundur's two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed controller.From the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.
文摘The Controller Area Network (CAN) is a well established control network for automotive and automation control applications. Time-Triggered Controller Area Network (TTCAN) is a recent development which introduces a session layer,for message scheduling,to the existing CAN standard,which is a two layer standard comprising of a physical layer and a data link layer. TTCAN facilitates network communication in a time-triggered fashion,by introducing a Time Division Multiple Access style communication scheme. This allows deterministic network behavior,where maximum message latency times can be quantified and guaranteed. In order to solve the problem of determinate time latency and synchronization among several districted units in one auto panel CAN systems,this paper proposed a prototype design implementation for a shared-clock scheduler based on PIC18F458 MCU. This leads to improved CAN system performance and avoid the latency jitters and guarantee a deterministic communication pattern on the bus. The real runtime performance is satisfied.
基金supported by the National High Technology Research and Development Program of China (863)(grant no.2007AA06Z220)Important Project of the Ministry of Education(grant no.307014)the Huainan Mining Group program
文摘Based on the production data of a large number of surface drainage wells in the Huainan mining area,the present study shows that four types of typical production characteristics for relieved methane wells are recognized,of which the stable type for production and gas concentration is the most dominate,as determined by a comprehensive study on the volume and concentration of drained gases, as well as the stress changes of rocks influenced by mining.Some influence factors for the productive differences of the drainage wells were also been discussed.The results indicate that protective coal-seam mining has a significant effect on overlying strata,which promotes the development of pores and fractures of coal reservoirs for methane desorption and migration;however,the production and the stability of drainage wells are affected by deformation and damage of the overlying strata.The second distribution of strata stress is caused by mining engineering,and if the stress load is larger than the carrying capacity of the extraction well,the gas production would be influenced by the drainage well that has been damaged by rock movement.Furthermore,the case damage occurs first in the weak, lithologic interface by its special mechanical properties.The stability of drainage wells and the production status are also influenced by the different drilling techniques,uneven distribution of gas concentration,and combination of gob gas and methane from the protected layer.
文摘The number of smokers in Chinese rural areas is more than 200 million, which is twice that in cities. It is very significant to carry out tobacco control interventions in rural areas. We performed this community intervention study to evaluate the efficacy of village-based health education of tobacco control on the male current smoking rate in rural areas. The population of this study was the males above 15 years old from 6 villages in rural areas. The villages were randomly assigned to intervention group or control group(3 villages in each group). Self-designed smoking questionnaire was applied. The intervention group received the village-based health education of tobacco control for one year. The primary outcome measurement was the male current smoking rate. In the baseline investigation, completed surveys were returned by 814 male residents from the control group and 831 male residents from the intervention group. The male current smoking rate in the control group and the intervention group was 61.2% and 58.5%, respectively, before intervention. There was no significant difference between these two groups(P〉0.05). After one-year intervention, the current smoking rate in the intervention group(51.2%) was significantly lower than that in the control group(62.8%)(P〈0.001). Our study suggested that the village-based health education of tobacco control was effective in lowering the male current smoking rate in rural areas, which could be a suitable and feasible way for tobacco control in the Chinese rural areas.
基金The Open Fund (PLC20180404) of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology)The Open Fund (PLN 201718) of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University)The Open Fund(SEC-2018-04)of Collaborative Innovation Center of Shale Gas Resources and Environment (Southwest Petroleum University)
文摘The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated.Shale cores underwent laboratory testing,which included the evaluation of total organic carbon(TOC),vitrinite reflectance(Ro),whole-rock X-ray diffraction(XRD),pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM).Based on the results of natural gamma ray spectrum logging,conventional logging,imaging logging,and seismic coherence properties,the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively.The results showed that(1)layer No.4(WF2-LM4)of the Wufeng-Longmaxi Formation has a Th/U ratio<2 and a Th/K ratio of 3.5–12.Graptolites and pyrite are relatively abundant in the shale core,indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2)The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen.There is a good correlation among TOC,Ro,gas content,and brittle minerals;the fracturing property(brittleness)is 57.3%.Organic and inorganic pores are moderately developed.A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3)The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects,and it is poorly preserved.The DY2 well is located far from the Qiyueshan Fault.Large faults are absent,and upward fractures in the Longmaxi Formation are poorly developed.The well is affected by low tectonic deformation intensity,and it is well preserved.(4)The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning.The thickness of the high-quality shale interval(WF2-LM4)is relatively small,which may be an important reason for the unstable production of shale gas thus far.Based on the systematic analysis of the geological factors controlling high-yield shale gas enrichment in the Dingshan area,and the comparative analysis with the surrounding typical exploration areas,the geological understanding of marine shale gas enrichment in southern China has been improved.Therefore,this study can provide a useful reference for shale gas exploration and further development.
文摘This paper firstly reviews the recent development in power system protection and control, with special attention paid to the wide-area and integrated protection, in order to look into future development of integration of protection and control for smart grids. This paper mainly reports on the development of integrated wide area protection and control for power systems. The concept of integrated wide area protection and control is introduced, in which a hierarchical protection and control system provides the protection and control of wide area or regional power substations/ plants and their associated power network. The system is mainly divided into three levels, the local, the substation/plant and the wide area/regional protection and control. The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between the levels. One of the core elements in the system is the synchronised wide area communication network between the substations and the protection and control system, in which latest communication technology is employed. Another important player in the system is the wide area synchronized protection and control information platform, which not only enables the fusion three line of defence for power system protection and control, but also provides a perfect tool for the application of cloud computing to substations and power networks.
文摘Analysis and study of clastic and clay minerals of surface sediments and their chemical composition in the sea area northwest of the Antarctic Peninsula enable the authors to divide this area basically into four mineralogical provinces : (1) the mineral ogical province of coast and island shelf of the Southern Shetland Islands, (2) the mineral ogical province of the eastern Bransfield Strait, (3) the mineral ogical province of the western Bransfield Strait, and (4) the mineral ogical province of the western Antarctic Peninsula. Finally, the relationships between the mineral distribution and geologic ,structure, material sources, glaciers, currents, and environments are briefly described.
基金supported by Open-ended Fund of Qinghai Province Key Laboratory of Physical Geography and Environmental Process(2018-QZH-K01)National Natural Science Foundation of China(41701505,41871064)the foundation of PHD development in Yichun University(201-3360118009)
文摘Historically,frequent and heavy snow disaster(SD)has caused serious livestock death and casualties,resulting in a devastating impact on animal husbandry development in the Three Rivers Source Region(TRSR).From winter in 2018 to spring in 2019,the largest SD occurred in this area over the past 10 years,especially in core zones of the Lancang River Source Region.Field research results show that the main causes of the major SD include weak infrastructure(i.e.,roads,communications,warm sheds,and insufficient forage reserve),low rate of domestic animals for sale before the SD,and low loss settlement rate.SD occurrence could furtherly reduce the ability of disaster prevention,mitigation and relief of disaster loss.In the future,heavily affected SD areas should improve the forecasting ability of snowfall incidents,strengthen infrastructure construction,implement grass and livestock balance strategies,optimize livestock structure,improve loss settlement rate,and develop a modern compound model of animal husbandry development model that combines breeding,slaughtering and deep processing of animal product.
文摘A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power systems worldwide and has led to operation of power systems closer to their stability limits and to power exchange in new patterns. These issues, as well as the on-going worldwide trend towards deregulation of the entire industry on the one hand and the increased need for accurate and better network monitoring on the other hand, force power utilities exposed to this pressure to demand new solutions for wide area monitoring, protection and control. Wide-area monitoring, protection, and control require communicating the specific-node information to a remote station but all information should be time synchronized so that to neutralize the time difference between information. It gives a complete simultaneous snap shot of the power system. The conventional system is not able to satisfy the time-synchronized requirement of power system. Phasor Measurement Unit (PMU) is enabler of time-synchronized measurement, it communicate the synchronized local information to remote station.