On the basis of comparative analysis on the vegetable input-output efficiency of suburban and rural areas in 2011- 2012,this paper made co-integration test,impulse response and variance decomposition for the vegetable...On the basis of comparative analysis on the vegetable input-output efficiency of suburban and rural areas in 2011- 2012,this paper made co-integration test,impulse response and variance decomposition for the vegetable input-output relationship of suburban areas in 1998-2012. Comparative analysis indicated that the vegetable input-output benefit of suburban area declines,while that of rural area rises; empirical analysis indicated that there is a long-term stable relationship between labor cost of vegetable planting and vegetable income and between material cost of vegetable planting and vegetable income,but the vegetable income itself has certain lag effect,followed by material cost,and the labor cost has minimum influence. Finally,it came up with recommendations for improving suburban vegetable input-output relationship,including improving vegetable input security mechanism,improving farmers' quality and innovation ability,and increasing technological input.展开更多
为了解决工业发展导致的灌区土壤投入品残留污染问题,给出一种基于地理信息系统(geographic information system,GIS)的土壤污染监测预警系统。该系统结合VOC-PF1型传感器、STM32主控芯片和GSM通信模块,实现了高效的数据采集和通信功能...为了解决工业发展导致的灌区土壤投入品残留污染问题,给出一种基于地理信息系统(geographic information system,GIS)的土壤污染监测预警系统。该系统结合VOC-PF1型传感器、STM32主控芯片和GSM通信模块,实现了高效的数据采集和通信功能。通过反距离加权(inverse distance weighted,IDW)插值法进行空间分析,并设立预警阈值,实现对灌区土壤投入品残留污染的实时监测和预警。实验结果表明:该系统的监测精度高达98%,监测时长最高为49 s,具有很高的实用性和效率。研究结果不仅为灌区土壤投入品残留污染监测提供了有效手段,也为环境保护和农业可持续发展提供有力支持。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
基金Supported by Special Project for Vegetable Innovation Team Construction of Shandong Modern Agriculture Industrial Technology System(SDAIT-02-022-13)
文摘On the basis of comparative analysis on the vegetable input-output efficiency of suburban and rural areas in 2011- 2012,this paper made co-integration test,impulse response and variance decomposition for the vegetable input-output relationship of suburban areas in 1998-2012. Comparative analysis indicated that the vegetable input-output benefit of suburban area declines,while that of rural area rises; empirical analysis indicated that there is a long-term stable relationship between labor cost of vegetable planting and vegetable income and between material cost of vegetable planting and vegetable income,but the vegetable income itself has certain lag effect,followed by material cost,and the labor cost has minimum influence. Finally,it came up with recommendations for improving suburban vegetable input-output relationship,including improving vegetable input security mechanism,improving farmers' quality and innovation ability,and increasing technological input.
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.
