With the rural concealed communication cable as the study object, the shielding effectiveness of different slot shapes was analyzed by using LBEM （linear boundary element method）. The engineering example results sho...With the rural concealed communication cable as the study object, the shielding effectiveness of different slot shapes was analyzed by using LBEM （linear boundary element method）. The engineering example results showed that for twocore shielded cable, the coupling capacitance of trapezoid slots （asymmetric and symmetric） changed the most, followed by rectangular slots （asymmetric and symmetric）, and the changes of wedge slots were the smallest, but the change tenden- cies were consistent. In addition, with the increase of slot width of different slots, the coupling capacitance of tow-cored shielded cable showed small change.展开更多
The construction of a new socialist countryside is a strategic focus of future economic and social development of our country, including the construction of rural power grids under the new urbanization and development...The construction of a new socialist countryside is a strategic focus of future economic and social development of our country, including the construction of rural power grids under the new urbanization and development, it has played a crucial role in supporting and promoting. Due to historical reasons, China has not yet formed a sound and sustainable development of rural power system and management system. In order to meet the requirements under the new urbanization of rural construction, we provide a solid foundation for the development of new rural construction, and long-term development of rural electricity has become an urgent need to study the issue. At present, the reform in the field of rural electrification, rural power enterprise management, rural power system and other existing research we have conducted a preliminary study, but overall, the research in this area is still in the exploratory stage, we need a more systematic and in-depth research and discussion.展开更多
Incorporating modem and advanced technology （various electronic devices） to excavational machinery led to become more efficient, better quality and cost effective. The continuous development of equipment is also ver...Incorporating modem and advanced technology （various electronic devices） to excavational machinery led to become more efficient, better quality and cost effective. The continuous development of equipment is also very important in the earth moving procedures which require significant time and expense to achieve the so-called ＂precision agriculture＂ or rather ＂precise management of agricultural inputs＂. One of the ＂precision agricultural＂ works is the land leveling. In recent years, land leveling is done with the use of a scraper （blade） mounted on the agricultural tractor. An electronic system controls the height of the blade automatically, without any operator intervention. In this paper, the field efficiency of the tractor MF6290, of 135 Hp horsepower, is calculated with a leveling blade of 4 m width, in the land leveling of rice cultivation, and in the rotation of different crops in different land preparation conditions （initial and final slope） in the area of Thessaloniki, northern Greece. The raw data revealed that the performance of the tractor ranged from 0.402 to 0.82 lha/h, on a slope 0%, while for surfaces with different initial and final slope, it ranged from 0.107 to 0.118 ha/h.展开更多
Battery based standalone SHS （solar home systems） are installed in Malawi to expedite rural electrification. A study was conducted to analyze the performance of SHS in low and high insolation areas of Malawi. It is ...Battery based standalone SHS （solar home systems） are installed in Malawi to expedite rural electrification. A study was conducted to analyze the performance of SHS in low and high insolation areas of Malawi. It is found that if the system is designed in accordance to procedures stipulated in Malawi standards, then it is capable of operating annually with mean performance ratio of 0.68, PV array production factor of 0.88 and system efficiency of 78% indicating a good system performance. The system is more reliable in high insulation areas （loss of load probability = 0.09） and when the battery charging is given priority during daytime, the overall system＇s reliability is improved by 40%. However, if the system is under-designed its performance ratio is reduced considerably and the system becomes less reliable. In overall, SHS in Malawi perform reliably if the system is well designed and maintained.展开更多
The economic benefits of insect-resistant genetically modified(GM) crops have been well documented, but the impact of such crops and the consequent reduction in pesticide use on farmers' health remains largely unk...The economic benefits of insect-resistant genetically modified(GM) crops have been well documented, but the impact of such crops and the consequent reduction in pesticide use on farmers' health remains largely unknown. Through the analysis of the data collected from the physical examination from farmers in China, we show that GM rice significantly reduces pesticide use and the resultant not only visible but also invisible adverse effects on farmers' neurological, hematological, and electrolyte system. Hence, the commercialization of GM rice is expected to improve the health of farmers in developing countries, where pesticide application is necessary to mitigate crop loss.展开更多
This study aims to develop a water turbine suitable for ultra-low heads in open channels, with the end goal being the effective utilization of unutilized hydroelectric energy in agricultural water channels. We perform...This study aims to develop a water turbine suitable for ultra-low heads in open channels, with the end goal being the effective utilization of unutilized hydroelectric energy in agricultural water channels. We performed tests by applying a cross-flow runner to an open channel as an undershot water turbine while attempting to simplify the structure and eliminate the casing. We experimentally investigated the flow fields and performance of water tur- bines in states where the flow rate was constant for the undershot cross-flow water turbine mentioned above. In addition, we compared existing undershot water turbines with our undershot cross-flow water turbine after at- taching a bottom plate to the runner. From the results, we were able to clarify the following. Although the effec- tive head for cross-flow runners with no bottom plate was lower than those found in existing runners equipped with a bottom plate, the power output is greater in the high rotational speed range because of the high turbine ef- ficiency. Also, the runner with no bottom plate differed from rtmners that had a bottom plate in that no water was being wound up by the blades or retained between the blades, and the former received twice the flow due to the flow-through effect. As a result, the turbine efficiency was greater for runners with no bottom plate in the full ro- tational speed range compared with that found in runners that had a bottom plate.展开更多
基金Supported by the Science and Technology Program of the Education Department of Shaanxi Provincial Government(09JK378)the Key Scientific Research Fund of Shaanxi University of Technology(SLGKY12-02)~~
文摘With the rural concealed communication cable as the study object, the shielding effectiveness of different slot shapes was analyzed by using LBEM （linear boundary element method）. The engineering example results showed that for twocore shielded cable, the coupling capacitance of trapezoid slots （asymmetric and symmetric） changed the most, followed by rectangular slots （asymmetric and symmetric）, and the changes of wedge slots were the smallest, but the change tenden- cies were consistent. In addition, with the increase of slot width of different slots, the coupling capacitance of tow-cored shielded cable showed small change.
文摘The construction of a new socialist countryside is a strategic focus of future economic and social development of our country, including the construction of rural power grids under the new urbanization and development, it has played a crucial role in supporting and promoting. Due to historical reasons, China has not yet formed a sound and sustainable development of rural power system and management system. In order to meet the requirements under the new urbanization of rural construction, we provide a solid foundation for the development of new rural construction, and long-term development of rural electricity has become an urgent need to study the issue. At present, the reform in the field of rural electrification, rural power enterprise management, rural power system and other existing research we have conducted a preliminary study, but overall, the research in this area is still in the exploratory stage, we need a more systematic and in-depth research and discussion.
文摘Incorporating modem and advanced technology （various electronic devices） to excavational machinery led to become more efficient, better quality and cost effective. The continuous development of equipment is also very important in the earth moving procedures which require significant time and expense to achieve the so-called ＂precision agriculture＂ or rather ＂precise management of agricultural inputs＂. One of the ＂precision agricultural＂ works is the land leveling. In recent years, land leveling is done with the use of a scraper （blade） mounted on the agricultural tractor. An electronic system controls the height of the blade automatically, without any operator intervention. In this paper, the field efficiency of the tractor MF6290, of 135 Hp horsepower, is calculated with a leveling blade of 4 m width, in the land leveling of rice cultivation, and in the rotation of different crops in different land preparation conditions （initial and final slope） in the area of Thessaloniki, northern Greece. The raw data revealed that the performance of the tractor ranged from 0.402 to 0.82 lha/h, on a slope 0%, while for surfaces with different initial and final slope, it ranged from 0.107 to 0.118 ha/h.
文摘Battery based standalone SHS （solar home systems） are installed in Malawi to expedite rural electrification. A study was conducted to analyze the performance of SHS in low and high insolation areas of Malawi. It is found that if the system is designed in accordance to procedures stipulated in Malawi standards, then it is capable of operating annually with mean performance ratio of 0.68, PV array production factor of 0.88 and system efficiency of 78% indicating a good system performance. The system is more reliable in high insulation areas （loss of load probability = 0.09） and when the battery charging is given priority during daytime, the overall system＇s reliability is improved by 40%. However, if the system is under-designed its performance ratio is reduced considerably and the system becomes less reliable. In overall, SHS in Malawi perform reliably if the system is well designed and maintained.
基金supported by the International Development Research Center(106160-002)the National Natural Science Foundation of China(71333013,71210004)National Key Program on Genetically Modified New Varieties(2011ZX08015-002A)
文摘The economic benefits of insect-resistant genetically modified(GM) crops have been well documented, but the impact of such crops and the consequent reduction in pesticide use on farmers' health remains largely unknown. Through the analysis of the data collected from the physical examination from farmers in China, we show that GM rice significantly reduces pesticide use and the resultant not only visible but also invisible adverse effects on farmers' neurological, hematological, and electrolyte system. Hence, the commercialization of GM rice is expected to improve the health of farmers in developing countries, where pesticide application is necessary to mitigate crop loss.
文摘This study aims to develop a water turbine suitable for ultra-low heads in open channels, with the end goal being the effective utilization of unutilized hydroelectric energy in agricultural water channels. We performed tests by applying a cross-flow runner to an open channel as an undershot water turbine while attempting to simplify the structure and eliminate the casing. We experimentally investigated the flow fields and performance of water tur- bines in states where the flow rate was constant for the undershot cross-flow water turbine mentioned above. In addition, we compared existing undershot water turbines with our undershot cross-flow water turbine after at- taching a bottom plate to the runner. From the results, we were able to clarify the following. Although the effec- tive head for cross-flow runners with no bottom plate was lower than those found in existing runners equipped with a bottom plate, the power output is greater in the high rotational speed range because of the high turbine ef- ficiency. Also, the runner with no bottom plate differed from rtmners that had a bottom plate in that no water was being wound up by the blades or retained between the blades, and the former received twice the flow due to the flow-through effect. As a result, the turbine efficiency was greater for runners with no bottom plate in the full ro- tational speed range compared with that found in runners that had a bottom plate.
