To overcome the issues of high cost and continuous cropping obstacles in facility cultivation of Panax notoginseng_ F. H. Chen, satisfy the market demand, save the production cost, improve the utilization rate of fore...To overcome the issues of high cost and continuous cropping obstacles in facility cultivation of Panax notoginseng_ F. H. Chen, satisfy the market demand, save the production cost, improve the utilization rate of forest land, increase the in-come of forest farmers and protect the ecological environment, the cultivation tech-niques of high-quality P. notoginseng seedlings from Wenshan, Yunnan under four kinds of forests (walnut forest, China fir forest, grape forest and kiwi forest) were in-vestigated in this study. The results showed that the height growth, crown diameter, survival rate and 3-year-old tuber weight of P. notoginseng_under walnut forest were higher than those under the other three kinds of forests; the height growth, crown diameter, survival rate and 3-year-old tuber weight of P. notoginseng under China fir forest were higher than those under grape forest and kiwi forest; and the crown di-ameter and survival rate under grape forest were higher, and the height growth and tuber weight under grape forest were lower than those under kiwi forest. Walnut is a broad-leaved deciduous tree species, so large-scale cultivation of P. notoginseng_should be conducted under broadleaf deciduous forest with canopy density around 0.8, taking advantage of the cool environment and rich humus layer under forest. This cultivation technology could save labor, shade, fertilizer and other costs, and accord with the ecological habit and the growth rules of P. notoginseng, thus im-proving yield and achieving high economic benefit.展开更多
To solve the contradiction between supply and demand of land, the con- struction of land resource security guarantee system is an important part to coordi- nate the economic development and cultivated land protection ...To solve the contradiction between supply and demand of land, the con- struction of land resource security guarantee system is an important part to coordi- nate the economic development and cultivated land protection in the core grain pro- duction region. Based on the deep analysis on the land resources characteristics and problems using the combined method of literature review method with qualita- tive and quantitative analysis, we constructed the land resource security system for different categories according to the land use principles of optimization, intensivism, improvement, and overall planning, and proposed the corresponding supporting mea- sures. The results showed that controlling the new increase, promoting the reclama- tion and improvement of land are the basis for land resource security, clearing the idle, improving the utilization rate of stock are the core of the efficient use of land resources, and establishing a unified urban and rural construction land market is the key to promoting the economical and intensive utilization of land resources, provid- ing scientific basis for the sustainable utilization of land resources in the core grain production regions.展开更多
In order to simulate the evolution of affordable housing land use a dynamic model that combines cellular automata CA and a multi-agent system MAS is established.This paper aims to utilize the approach of decision fact...In order to simulate the evolution of affordable housing land use a dynamic model that combines cellular automata CA and a multi-agent system MAS is established.This paper aims to utilize the approach of decision factors on site selection of affordable housing through a literature review to construct a hierarchy model of those factors identifying the weight of each factor by an analytic hierarchy process AHP .Based on those weight factors the CA-MAS model is designed. Nanjing city is taken as an example to verify the feasibility of the model.The results show that the CA-MAS model is pragmatic and effective in simulating evolution of affordable housing land use which also promotes the fundamental understanding and perception of the development of affordable housing and urbanization.展开更多
The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Z...The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Zoige wetland mainly focus on the macro features of the wetland,while the influence of the surrounding faults on the Zoige wetland degradation is rarely studied.This study uses terrain data to analyze the cover change and the water loss caused by the Wqie-Seji fault based on the distributed hydrological model.The simulated water loss demonstrates that the Normalized Difference Vegetation Index(NDVI) is the most important factor for inducing water loss.The fault is also a factor that cannot be neglected,which has caused 33% of the wetland water loss.Therefore,it is of importance to study the influence of the fault on the wetland degradation.展开更多
When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is...When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.展开更多
Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based ...Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based upon a discernible matrix of the fractal dimension associated with line currents.The method builds on existing selective protection methods.Faulted feeders are distinguished using differences in the zero-sequence transient current fractal dimension.The current signals were first processed through a fast Fourier transform and then the characteristics of a faulted line were identified using a discernible matrix.The method of calculation is illustrated.The results show that the method involves simple calculations, is easy to do and is highly accurate.It is, therefore, suitable for distribution networks having different neutral grounding modes.展开更多
Lifelines, such as pipeline, transportation, communication, electric transmission and medical rescue systems, are complicated networks that always distribute spatially over large geological and geographic units. The q...Lifelines, such as pipeline, transportation, communication, electric transmission and medical rescue systems, are complicated networks that always distribute spatially over large geological and geographic units. The quantification of their reliability under an earthquake occurrence should be highly regarded, because the performance of these systems during a destructive earthquake is vital in order to estimate direct and indirect economic losses from lifeline failures, and is also related to laying out a rescue plan. The research in this paper aims to develop a new earthquake reliability calculation methodology for lifeline systems. The methodology of the network reliability for lifeline systems is based on fault tree analysis (FTA) and geological information system (GIS). The interactions existing in a lifeline system ale considered herein. The lifeline systems are idealized as equivalent networks, consisting of nodes and links, and are described by network analysis in GIS. Firstly, the node is divided into two types: simple node and complicated node, where the reliability of the complicated node is calculated by FTA and interaction is regarded as one factor to affect performance of the nodes. The reliability of simple node and link is evaluated by code. Then, the reliability of the entilre network is assessed based on GIS and FTA. Lastly, an illustration is given to show the methodology.展开更多
As the highest and most extensive plateau on earth, the Tibetan Plateau has strong thermo- dynamic effect, which not only affects regional climate around the plateau but precipitation patterns of scattered meteorologi...As the highest and most extensive plateau on earth, the Tibetan Plateau has strong thermo- dynamic effect, which not only affects regional climate around the plateau but precipitation patterns of scattered meteorological also temperature and itself. However, due to stations, its spatial precipitation pattern and, especially, the mechanism behind are poorly understood. The availability of spatially consistent satellite-derived precipitation data makes it possible to get accurate precipitation pattern in the plateau, which could help quantitatively explore the effect and mechanism of mass elevation effect on precipitation pattern. This paper made full use of TMPA 3B43 V7 monthly precipitation data to track the trajectory of precipitation and identified four routes (east, southeast, south, west directions) along which moisture-laden air masses move into the plateau. We made the assumption that precipitation pattern is the result interplay of these four moisture- laden air masses transportation routes against the distances from moisture sources and the topographic barriers along the routes. To do so, we developed a multivariate linear regression model with the spatial distribution of annual mean precipitation as the dependent variable and the topographical barriers to these four moisture sources as independent variables. The result shows that our model could explain about 7o% of spatial variation of mean annual precipitation pattern in the plateau; the regression analysis also shows that the southeast moisture source (the Bay of Bengal) contributes the most (32.56%) to the rainfall pattern of the plateau; the east and the south sources have nearly the same contribution, 23.59% and 23.48%, respectively; while the west source contributes the least, only 2o.37%. The findings of this study can greatly improve our understanding of mass elevation effect on spatial precipitation pattern.展开更多
The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding curren...The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.展开更多
One of the major challenges in reservoir characterization is to estimate the effective porosity and the permeability of the reservoir due to reservoir heterogeneity. Often, the vertical and the horizontal permeabiliti...One of the major challenges in reservoir characterization is to estimate the effective porosity and the permeability of the reservoir due to reservoir heterogeneity. Often, the vertical and the horizontal permeabilities are not considered separately in 3D geo-cellular models and in the reservoir simulations. Conventional reservoir modeling extrapolates all of the small-scale data to full-field scale data without considering the impact of the small-scale geological details, and therefore carries forward inherent errors into the reservoir predictions as a consequence of ignoring the reservoir heterogeneity. Most reservoirs are geologically complex and heterogeneous and that greatly influences reservoir performance. A case study is taken from a CHOPS (cold heavy oil production with sands) field. An innovative method of reservoir heterogeneity estimation has been introduced to illustrate the complex reservoir heterogeneity honouring all of the small-scale geological details in the 3D geological model. This detailed near-wellbore modeling through a synthetic core can provide the realistic quantitative volumetric assumption of the production prediction and improve the EOR (enhanced oil recovery) processes.展开更多
A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in this paper.A special d...A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in this paper.A special diagnostic signal current is injected into the fault distribution system,and then it is detected at the outlet terminals to identify the fault line and at the sectionalizing or branching point along the fault line to locate the fault section.The method has been put into application in actual distribution network and field experience shows that it can identify the fault line and locate the fault section correctly and effectively.展开更多
An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence netwo...An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence network as fault-location model in which the source impedance at the remote end is not involved, ef-fectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The algorithm achieves accurate location by measuring only one local end data and is used in a procedure that provides automatic determination of faulted types and phases, and does not require the engineer to specify them. Simulation results showed the effectiveness of the algorithm under the condition of double phase-to-earth fault.展开更多
This paper presents a new earth-fault detection algorithm for unearthed (isolated) and compensated neutral medium voltage (MV) networks. The proposed algorithm is based on capacitance calculation from transient im...This paper presents a new earth-fault detection algorithm for unearthed (isolated) and compensated neutral medium voltage (MV) networks. The proposed algorithm is based on capacitance calculation from transient impedance and dominant transient frequency. The Discrete Fourier Transform (DFT) method is used to determine the dominant transient frequency. The values of voltage and current earth modes are calculated in the period of the dominant transient frequency, then the transient impedance can be determined, from which we can calculate the earth capacitance. The calculated capacitance gives an indication about if the feeder is faulted or not. The algorithm is less dependent on the fault resistance and the faulted feeder parameters; it mainly depends on the background network. The network is simulated by ATP/EMTP program. Several different fault conditions are covered in the simulation process, different fault inception angles, fault locations and fault resistances.展开更多
In this paper, we demonstrate the high resolution seismic reflection data for a depth range of several hundred meters across the Fenhe fault in Taiyuan city, China. In combination with the relevant borehole logs, thes...In this paper, we demonstrate the high resolution seismic reflection data for a depth range of several hundred meters across the Fenhe fault in Taiyuan city, China. In combination with the relevant borehole logs, these data provide useful constraints on the accurate position, geometry and deformation rate of the fault, as well as the kinematics of recent fault motion. The high resolution seismic reflection profiling revealed that the western branch of the Fenhe fault is a high angle, eastward dipping, oblique normal fault, and cutting up to the lower part of the Quaternary system. It was revealed that the top breaking point of this fault is at a depth of ~70m below the ground surface. A borehole log across the Fenhe fault permitted us to infer that there are two high angle, oppositely dipping, oblique normal faults. The eastem branch lies beneath the eastern embankment of the Fenhe river, dipping to the west and cutting into the Holocene late Pleistocene strata with a maximum vertical offset of ~8m. Another borehole log across the northern segment of the Fenhe fault indicates that the western branch of this fault has cut into the Holocene late Pleistocene strata with a maximum vertical offset of ~6m. The above mentioned data provide a minimum average Pleistocene Holocene vertical slip rate of 0 06~0 08mm/a and a maximum average large earthquake recurrence interval of 5 0~6 7ka for the Fenhe fault.展开更多
The paper looks at some bridge structures from ancient aqueducts to the most recent viaducts since people have always built structures that help them to cross terrain obstacles such as rivers, ravines and hills. Their...The paper looks at some bridge structures from ancient aqueducts to the most recent viaducts since people have always built structures that help them to cross terrain obstacles such as rivers, ravines and hills. Their primary goal has functionality and efficiency rather than aesthetic considerations and, yet from a time perspective, they still impress with their beauty and perfection. Gradually, architects began to take care of the form of bridges, as in the case of the Rialto Bridge in Venice. Nowadays, the most renowned architects, with Norman Foster in the lead, take up the design of bridge "architecture". Although technical solutions remain top priority, aesthetic qualities are widely recognized and appreciated.展开更多
Micro-seismic phenomena, occurring when rock masses are subjected to forces and failures, allow the determination of their unstable states and failure zones by analyzing micro-seismic signals. We first present the pri...Micro-seismic phenomena, occurring when rock masses are subjected to forces and failures, allow the determination of their unstable states and failure zones by analyzing micro-seismic signals. We first present the principles of micro-seismic monitoring and location, as well as an underground explosion-proof micro-seismic monitoring system. Given a practical engineering application, we describe the application of micro-seismic monitoring technology in determining the height of a "two-zone" overburden, i.e., a caving zone and a fracture zone, the width of a coal-pillar section and the depth of failure of a floor. The workfaces monitored accomplished safe and highly efficient mining based on our micro-seismic monitoring results and provide direct proof of the reliability and validity of micro-seismic monitoring technology.展开更多
In order to fulfill the needs of life-support oxygen supply during the development of plateau mineral resources,four oxygen supply patterns suitable for the plateau mine in specific environment were developed:tunnel f...In order to fulfill the needs of life-support oxygen supply during the development of plateau mineral resources,four oxygen supply patterns suitable for the plateau mine in specific environment were developed:tunnel face diffusive oxygen supply,tunnel oxygen-bar car,carried oxygen cylinder and portable oxygen generator. Through the study of safety oxygen supply experiments in low- pressure plateau areas,the mathematical relationship between maximum integration of secure oxygen volume and altitude has been achieved. Oxygen supply safety control should follow this relationship in plateau mines during the time of executing tunnel face or in room air diffusive oxygen supply. The application results of life-support oxygen supplement technologies in the development of mineral resources in high altitude areas show that the oxygen supply for tunneling miners in plateau mines can not only effectively enhance the oxygen saturation,reduce the pulse rate and the breath rate per minute,but also improve various symptoms caused by altitude hypoxia and high-intensity physical labor.展开更多
Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to oc...Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to occur on the system. Different types of studies are usually done on electric power systems to determine how the system behaves before, during and after a fault condition. The behaviour of variables of interest such as currents, voltage, rotor angle and active and reactive power under fault conditions are studied and observed to help determine possible causes of faults in a power system. The objective of this paper is to investigate a fault that occurred on the 330 kV transmission line between Ruacana power station and Omburu sub-station, the fault caused all the generators at Ruacana power station to trip and consequently caused a blackout at the power station that lasted for 6 h. Preliminary findings showed that the observed fault was an earth fault but the exact type of earth fault was however not known at the time. This research investigation sets out to determine the exact fault that occurred; the most probable cause of the fault, and propose possible solutions to prevent reoccurrence of such a fault. The section of the power network in which the fault occurred was modelled using DigSilent Power Factory software tool, and transient fault analysis was carried out on the model for different fault conditions. Results obtained were then compared with data obtained from NamPower records to ascertain the type of fault.展开更多
The Tianjin fault includes South Tianjin fault and North Tianjin fault. Based on the results of artificial seismic exploration,four borehole profiles were laid out respectively west of Jinghai county town,Chaomidian v...The Tianjin fault includes South Tianjin fault and North Tianjin fault. Based on the results of artificial seismic exploration,four borehole profiles were laid out respectively west of Jinghai county town,Chaomidian village of Xiqing district,Xiaonanhe village of Xiqing district and Zhutoudian village of Ninghe county,to implement the exploration of these faults. Through identification of microfossils,the locations of marine beds in boreholes were obtained in this work,and through stratigraphic dating,the ages of the first,second and third marine beds were determined. Through strata correlation with the marine beds as key marker beds and integrating with the test results of paleo geomagnetism of boreholes BZ2 and TN3,the activity in the North and South Tianjin faults was analyzed and studied. The results indicate that there is no evidence of movement of the South Tianjin fault since the Late Pleistocene,but may have had weak activity before the Middle Pleistocene. No evidence of activity in the North Tianjin fault was found since the Late Pleistocene either,but might have been active in the early stage of the Early Pleistocene. These show that the activity of the South Tianjin fault is stronger than that of the North Tianjin fault. At the same time,we find that the second,third and fourth marine beds are lacking to some extent in different areas. So,before they are used in strata correlation, the age of marine beds must be determined,otherwise the results of strata correlation may lead to errors. For the second marine bed,where there has been dispute about its age,we consider the age to be about 70ka.展开更多
To meet the demand of raw material, i.e., wood, from the available sources always remained a big challenge for paper industries since the last two decades. For a sustainable supply of raw material in future, major pla...To meet the demand of raw material, i.e., wood, from the available sources always remained a big challenge for paper industries since the last two decades. For a sustainable supply of raw material in future, major plantation activities were undertaken by paper industries, like West Coast Paper Mills Limited (WCPM), by constituting a society, i.e., Society for Afforestation, Research and Allied Works (SARA), Dandeli in 2001. The main aim was to promote afforestation programme through major plantations activities on the degraded lands (under rainfed condition) and to generate employments and capacity building. The WCPM is a leading paper manufacturing industry of the country (under the flagship of Bangur group) located at the bank of Kali River in Dandeli of Uttar Kannada district in State Karnataka. To date, company through SARA has raised captive plantations on more than 50,000 acres of degraded land by farmers in different districts of Maharashtm, Karnataka, Andhra Pradesh and Tamilnadu States under Captive Plantation Project through Contract for Farming (CFF) since 2006 under a simple agreement period of only five years. After five years, society arranged to harvest the first rotation crop of the farmer of 2006, 2007, 2008, 2009 plantations and paid the amount of the crop directly to farmers. SARA has a mutual contract with WCPM for purchasing pulpwood. With this, farmers are getting full amount of their crop harvested after five years without any hurdle through SARA. SARA did all the expenditures, i.e., from land development, plantation and harvesting. Under its agroforestry plantation programme, superior planting material of various pulpwood species suited to particular area, i.e., Eucalyptus, Subabul, Casuarina and Acacia were planted on farmer's land. Farmers were also encouraged for intercropping, like maize, peanut (groundnut), chilly, tomato and ginger with plantations. Apart from this, SARA is also providing free fodder to the livestock of farmers. Various types of fodder species such as Stylosanthes scabra, S. hamata are grown with plantation. SARA has also set up its own hi-tech clonal nursery developing around 5-6 millions of clonal ramets every year through clonal propagation technology. Till date, SARA has received 0.15 million ton (MT) of pulpwood from the plantations on farmer's land with a yield of 25-30 MT/acre. This type of activities will prove a boon for farmers as well as for industry, when raw material is going to be short in India. It will also conserve our natural resources, high conservative valued forests (HCVF) and will reduce the pressure on forest for wood. In addition, this will maintain the balance between environment and nature. To meet the requirement of pulpwood for industry, this type of plantation activities will open new ways for industry to secure raw material for future use. Also, this would be helpful to enhance productivity and generate employments for rural communities to improve their living standard and capacity building.展开更多
基金Supported by Central Financial Forestry Science and Technology Extension Project of China([2016]XT001)Science and Technology Development Project of Hunan Province(S2014F209021)~~
文摘To overcome the issues of high cost and continuous cropping obstacles in facility cultivation of Panax notoginseng_ F. H. Chen, satisfy the market demand, save the production cost, improve the utilization rate of forest land, increase the in-come of forest farmers and protect the ecological environment, the cultivation tech-niques of high-quality P. notoginseng seedlings from Wenshan, Yunnan under four kinds of forests (walnut forest, China fir forest, grape forest and kiwi forest) were in-vestigated in this study. The results showed that the height growth, crown diameter, survival rate and 3-year-old tuber weight of P. notoginseng_under walnut forest were higher than those under the other three kinds of forests; the height growth, crown diameter, survival rate and 3-year-old tuber weight of P. notoginseng under China fir forest were higher than those under grape forest and kiwi forest; and the crown di-ameter and survival rate under grape forest were higher, and the height growth and tuber weight under grape forest were lower than those under kiwi forest. Walnut is a broad-leaved deciduous tree species, so large-scale cultivation of P. notoginseng_should be conducted under broadleaf deciduous forest with canopy density around 0.8, taking advantage of the cool environment and rich humus layer under forest. This cultivation technology could save labor, shade, fertilizer and other costs, and accord with the ecological habit and the growth rules of P. notoginseng, thus im-proving yield and achieving high economic benefit.
文摘To solve the contradiction between supply and demand of land, the con- struction of land resource security guarantee system is an important part to coordi- nate the economic development and cultivated land protection in the core grain pro- duction region. Based on the deep analysis on the land resources characteristics and problems using the combined method of literature review method with qualita- tive and quantitative analysis, we constructed the land resource security system for different categories according to the land use principles of optimization, intensivism, improvement, and overall planning, and proposed the corresponding supporting mea- sures. The results showed that controlling the new increase, promoting the reclama- tion and improvement of land are the basis for land resource security, clearing the idle, improving the utilization rate of stock are the core of the efficient use of land resources, and establishing a unified urban and rural construction land market is the key to promoting the economical and intensive utilization of land resources, provid- ing scientific basis for the sustainable utilization of land resources in the core grain production regions.
基金The National Social Science Foundation of China(No.14AJY013)the Scientific Innovation Research of College Graduates in Jiangsu Province(No.CXLX13_126)
文摘In order to simulate the evolution of affordable housing land use a dynamic model that combines cellular automata CA and a multi-agent system MAS is established.This paper aims to utilize the approach of decision factors on site selection of affordable housing through a literature review to construct a hierarchy model of those factors identifying the weight of each factor by an analytic hierarchy process AHP .Based on those weight factors the CA-MAS model is designed. Nanjing city is taken as an example to verify the feasibility of the model.The results show that the CA-MAS model is pragmatic and effective in simulating evolution of affordable housing land use which also promotes the fundamental understanding and perception of the development of affordable housing and urbanization.
基金supported by the National Key Project of Scientific and Technical Supporting Programs of the Ministry of Science&Technology of China(Grant No.2007BAC18B01)the Project of Ministry of Environmental Protection of China(Grant No.200809086),the Project of Ministry of Environmental Protection of China(Grant No.200909060)the Project of Scientific Research and Technological Development of Guangxi(Grant NO.GKG1140002-2-4)
文摘The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Zoige wetland mainly focus on the macro features of the wetland,while the influence of the surrounding faults on the Zoige wetland degradation is rarely studied.This study uses terrain data to analyze the cover change and the water loss caused by the Wqie-Seji fault based on the distributed hydrological model.The simulated water loss demonstrates that the Normalized Difference Vegetation Index(NDVI) is the most important factor for inducing water loss.The fault is also a factor that cannot be neglected,which has caused 33% of the wetland water loss.Therefore,it is of importance to study the influence of the fault on the wetland degradation.
文摘When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.
基金Project 50504015 supported by the National Natural Science Foundation of Chinathe Youth Science and Technology Research Program of China University of Mining and Technology (0C060996)
文摘Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based upon a discernible matrix of the fractal dimension associated with line currents.The method builds on existing selective protection methods.Faulted feeders are distinguished using differences in the zero-sequence transient current fractal dimension.The current signals were first processed through a fast Fourier transform and then the characteristics of a faulted line were identified using a discernible matrix.The method of calculation is illustrated.The results show that the method involves simple calculations, is easy to do and is highly accurate.It is, therefore, suitable for distribution networks having different neutral grounding modes.
基金Sponsored by the Natural Science Foundation of China (Grant No.50278028) the Scientific Research Foundation of Harbin Institute of Technology(Grant No.HIT200079).
文摘Lifelines, such as pipeline, transportation, communication, electric transmission and medical rescue systems, are complicated networks that always distribute spatially over large geological and geographic units. The quantification of their reliability under an earthquake occurrence should be highly regarded, because the performance of these systems during a destructive earthquake is vital in order to estimate direct and indirect economic losses from lifeline failures, and is also related to laying out a rescue plan. The research in this paper aims to develop a new earthquake reliability calculation methodology for lifeline systems. The methodology of the network reliability for lifeline systems is based on fault tree analysis (FTA) and geological information system (GIS). The interactions existing in a lifeline system ale considered herein. The lifeline systems are idealized as equivalent networks, consisting of nodes and links, and are described by network analysis in GIS. Firstly, the node is divided into two types: simple node and complicated node, where the reliability of the complicated node is calculated by FTA and interaction is regarded as one factor to affect performance of the nodes. The reliability of simple node and link is evaluated by code. Then, the reliability of the entilre network is assessed based on GIS and FTA. Lastly, an illustration is given to show the methodology.
基金funded by the National Natural Science Foundation of China(Grant Nos.41421001 and 41030528)
文摘As the highest and most extensive plateau on earth, the Tibetan Plateau has strong thermo- dynamic effect, which not only affects regional climate around the plateau but precipitation patterns of scattered meteorological also temperature and itself. However, due to stations, its spatial precipitation pattern and, especially, the mechanism behind are poorly understood. The availability of spatially consistent satellite-derived precipitation data makes it possible to get accurate precipitation pattern in the plateau, which could help quantitatively explore the effect and mechanism of mass elevation effect on precipitation pattern. This paper made full use of TMPA 3B43 V7 monthly precipitation data to track the trajectory of precipitation and identified four routes (east, southeast, south, west directions) along which moisture-laden air masses move into the plateau. We made the assumption that precipitation pattern is the result interplay of these four moisture- laden air masses transportation routes against the distances from moisture sources and the topographic barriers along the routes. To do so, we developed a multivariate linear regression model with the spatial distribution of annual mean precipitation as the dependent variable and the topographical barriers to these four moisture sources as independent variables. The result shows that our model could explain about 7o% of spatial variation of mean annual precipitation pattern in the plateau; the regression analysis also shows that the southeast moisture source (the Bay of Bengal) contributes the most (32.56%) to the rainfall pattern of the plateau; the east and the south sources have nearly the same contribution, 23.59% and 23.48%, respectively; while the west source contributes the least, only 2o.37%. The findings of this study can greatly improve our understanding of mass elevation effect on spatial precipitation pattern.
基金The financial support from the National Natural Science Foundation of China (No. 51107143)
文摘The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.
文摘One of the major challenges in reservoir characterization is to estimate the effective porosity and the permeability of the reservoir due to reservoir heterogeneity. Often, the vertical and the horizontal permeabilities are not considered separately in 3D geo-cellular models and in the reservoir simulations. Conventional reservoir modeling extrapolates all of the small-scale data to full-field scale data without considering the impact of the small-scale geological details, and therefore carries forward inherent errors into the reservoir predictions as a consequence of ignoring the reservoir heterogeneity. Most reservoirs are geologically complex and heterogeneous and that greatly influences reservoir performance. A case study is taken from a CHOPS (cold heavy oil production with sands) field. An innovative method of reservoir heterogeneity estimation has been introduced to illustrate the complex reservoir heterogeneity honouring all of the small-scale geological details in the 3D geological model. This detailed near-wellbore modeling through a synthetic core can provide the realistic quantitative volumetric assumption of the production prediction and improve the EOR (enhanced oil recovery) processes.
基金Postdoctoral Foundation of China(No.20070410755)PAN Zhencun,born in 1962,male,postdoctor researcher.
文摘A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in this paper.A special diagnostic signal current is injected into the fault distribution system,and then it is detected at the outlet terminals to identify the fault line and at the sectionalizing or branching point along the fault line to locate the fault section.The method has been put into application in actual distribution network and field experience shows that it can identify the fault line and locate the fault section correctly and effectively.
文摘An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence network as fault-location model in which the source impedance at the remote end is not involved, ef-fectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The algorithm achieves accurate location by measuring only one local end data and is used in a procedure that provides automatic determination of faulted types and phases, and does not require the engineer to specify them. Simulation results showed the effectiveness of the algorithm under the condition of double phase-to-earth fault.
文摘This paper presents a new earth-fault detection algorithm for unearthed (isolated) and compensated neutral medium voltage (MV) networks. The proposed algorithm is based on capacitance calculation from transient impedance and dominant transient frequency. The Discrete Fourier Transform (DFT) method is used to determine the dominant transient frequency. The values of voltage and current earth modes are calculated in the period of the dominant transient frequency, then the transient impedance can be determined, from which we can calculate the earth capacitance. The calculated capacitance gives an indication about if the feeder is faulted or not. The algorithm is less dependent on the fault resistance and the faulted feeder parameters; it mainly depends on the background network. The network is simulated by ATP/EMTP program. Several different fault conditions are covered in the simulation process, different fault inception angles, fault locations and fault resistances.
文摘In this paper, we demonstrate the high resolution seismic reflection data for a depth range of several hundred meters across the Fenhe fault in Taiyuan city, China. In combination with the relevant borehole logs, these data provide useful constraints on the accurate position, geometry and deformation rate of the fault, as well as the kinematics of recent fault motion. The high resolution seismic reflection profiling revealed that the western branch of the Fenhe fault is a high angle, eastward dipping, oblique normal fault, and cutting up to the lower part of the Quaternary system. It was revealed that the top breaking point of this fault is at a depth of ~70m below the ground surface. A borehole log across the Fenhe fault permitted us to infer that there are two high angle, oppositely dipping, oblique normal faults. The eastem branch lies beneath the eastern embankment of the Fenhe river, dipping to the west and cutting into the Holocene late Pleistocene strata with a maximum vertical offset of ~8m. Another borehole log across the northern segment of the Fenhe fault indicates that the western branch of this fault has cut into the Holocene late Pleistocene strata with a maximum vertical offset of ~6m. The above mentioned data provide a minimum average Pleistocene Holocene vertical slip rate of 0 06~0 08mm/a and a maximum average large earthquake recurrence interval of 5 0~6 7ka for the Fenhe fault.
文摘The paper looks at some bridge structures from ancient aqueducts to the most recent viaducts since people have always built structures that help them to cross terrain obstacles such as rivers, ravines and hills. Their primary goal has functionality and efficiency rather than aesthetic considerations and, yet from a time perspective, they still impress with their beauty and perfection. Gradually, architects began to take care of the form of bridges, as in the case of the Rialto Bridge in Venice. Nowadays, the most renowned architects, with Norman Foster in the lead, take up the design of bridge "architecture". Although technical solutions remain top priority, aesthetic qualities are widely recognized and appreciated.
基金supported by the National Basic Research Program of China (No. 2010CB226805)the National Natural Science Foundation of China (No. 50874103)+1 种基金the State Laboratory Fund (No. SKLGDUEK0905)the Talent Introduction Fund of Anhui University of Science & Technology
文摘Micro-seismic phenomena, occurring when rock masses are subjected to forces and failures, allow the determination of their unstable states and failure zones by analyzing micro-seismic signals. We first present the principles of micro-seismic monitoring and location, as well as an underground explosion-proof micro-seismic monitoring system. Given a practical engineering application, we describe the application of micro-seismic monitoring technology in determining the height of a "two-zone" overburden, i.e., a caving zone and a fracture zone, the width of a coal-pillar section and the depth of failure of a floor. The workfaces monitored accomplished safe and highly efficient mining based on our micro-seismic monitoring results and provide direct proof of the reliability and validity of micro-seismic monitoring technology.
基金"973"National Key Basic Research and Development Program(No.2012CB518202)Project of Qinghai Development of Science and Technology(No.2011-N-150)
文摘In order to fulfill the needs of life-support oxygen supply during the development of plateau mineral resources,four oxygen supply patterns suitable for the plateau mine in specific environment were developed:tunnel face diffusive oxygen supply,tunnel oxygen-bar car,carried oxygen cylinder and portable oxygen generator. Through the study of safety oxygen supply experiments in low- pressure plateau areas,the mathematical relationship between maximum integration of secure oxygen volume and altitude has been achieved. Oxygen supply safety control should follow this relationship in plateau mines during the time of executing tunnel face or in room air diffusive oxygen supply. The application results of life-support oxygen supplement technologies in the development of mineral resources in high altitude areas show that the oxygen supply for tunneling miners in plateau mines can not only effectively enhance the oxygen saturation,reduce the pulse rate and the breath rate per minute,but also improve various symptoms caused by altitude hypoxia and high-intensity physical labor.
文摘Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to occur on the system. Different types of studies are usually done on electric power systems to determine how the system behaves before, during and after a fault condition. The behaviour of variables of interest such as currents, voltage, rotor angle and active and reactive power under fault conditions are studied and observed to help determine possible causes of faults in a power system. The objective of this paper is to investigate a fault that occurred on the 330 kV transmission line between Ruacana power station and Omburu sub-station, the fault caused all the generators at Ruacana power station to trip and consequently caused a blackout at the power station that lasted for 6 h. Preliminary findings showed that the observed fault was an earth fault but the exact type of earth fault was however not known at the time. This research investigation sets out to determine the exact fault that occurred; the most probable cause of the fault, and propose possible solutions to prevent reoccurrence of such a fault. The section of the power network in which the fault occurred was modelled using DigSilent Power Factory software tool, and transient fault analysis was carried out on the model for different fault conditions. Results obtained were then compared with data obtained from NamPower records to ascertain the type of fault.
基金funded by National Development and Reform Commission (NDRC)the People's Republic of China as the project"Experimental Exploration of Active Faults in Urban Area"(Grant No 20041138)
文摘The Tianjin fault includes South Tianjin fault and North Tianjin fault. Based on the results of artificial seismic exploration,four borehole profiles were laid out respectively west of Jinghai county town,Chaomidian village of Xiqing district,Xiaonanhe village of Xiqing district and Zhutoudian village of Ninghe county,to implement the exploration of these faults. Through identification of microfossils,the locations of marine beds in boreholes were obtained in this work,and through stratigraphic dating,the ages of the first,second and third marine beds were determined. Through strata correlation with the marine beds as key marker beds and integrating with the test results of paleo geomagnetism of boreholes BZ2 and TN3,the activity in the North and South Tianjin faults was analyzed and studied. The results indicate that there is no evidence of movement of the South Tianjin fault since the Late Pleistocene,but may have had weak activity before the Middle Pleistocene. No evidence of activity in the North Tianjin fault was found since the Late Pleistocene either,but might have been active in the early stage of the Early Pleistocene. These show that the activity of the South Tianjin fault is stronger than that of the North Tianjin fault. At the same time,we find that the second,third and fourth marine beds are lacking to some extent in different areas. So,before they are used in strata correlation, the age of marine beds must be determined,otherwise the results of strata correlation may lead to errors. For the second marine bed,where there has been dispute about its age,we consider the age to be about 70ka.
文摘To meet the demand of raw material, i.e., wood, from the available sources always remained a big challenge for paper industries since the last two decades. For a sustainable supply of raw material in future, major plantation activities were undertaken by paper industries, like West Coast Paper Mills Limited (WCPM), by constituting a society, i.e., Society for Afforestation, Research and Allied Works (SARA), Dandeli in 2001. The main aim was to promote afforestation programme through major plantations activities on the degraded lands (under rainfed condition) and to generate employments and capacity building. The WCPM is a leading paper manufacturing industry of the country (under the flagship of Bangur group) located at the bank of Kali River in Dandeli of Uttar Kannada district in State Karnataka. To date, company through SARA has raised captive plantations on more than 50,000 acres of degraded land by farmers in different districts of Maharashtm, Karnataka, Andhra Pradesh and Tamilnadu States under Captive Plantation Project through Contract for Farming (CFF) since 2006 under a simple agreement period of only five years. After five years, society arranged to harvest the first rotation crop of the farmer of 2006, 2007, 2008, 2009 plantations and paid the amount of the crop directly to farmers. SARA has a mutual contract with WCPM for purchasing pulpwood. With this, farmers are getting full amount of their crop harvested after five years without any hurdle through SARA. SARA did all the expenditures, i.e., from land development, plantation and harvesting. Under its agroforestry plantation programme, superior planting material of various pulpwood species suited to particular area, i.e., Eucalyptus, Subabul, Casuarina and Acacia were planted on farmer's land. Farmers were also encouraged for intercropping, like maize, peanut (groundnut), chilly, tomato and ginger with plantations. Apart from this, SARA is also providing free fodder to the livestock of farmers. Various types of fodder species such as Stylosanthes scabra, S. hamata are grown with plantation. SARA has also set up its own hi-tech clonal nursery developing around 5-6 millions of clonal ramets every year through clonal propagation technology. Till date, SARA has received 0.15 million ton (MT) of pulpwood from the plantations on farmer's land with a yield of 25-30 MT/acre. This type of activities will prove a boon for farmers as well as for industry, when raw material is going to be short in India. It will also conserve our natural resources, high conservative valued forests (HCVF) and will reduce the pressure on forest for wood. In addition, this will maintain the balance between environment and nature. To meet the requirement of pulpwood for industry, this type of plantation activities will open new ways for industry to secure raw material for future use. Also, this would be helpful to enhance productivity and generate employments for rural communities to improve their living standard and capacity building.