The methods of estimating the minimum allowed value of IFOV (instantaneous field of view) of the detector in a rosette scan system are investigated. The common method for the estimation of IFOV is described. A new met...The methods of estimating the minimum allowed value of IFOV (instantaneous field of view) of the detector in a rosette scan system are investigated. The common method for the estimation of IFOV is described. A new method which uses the maximum distance between two neighboring petals as the estimated value of IFOV is developed and a comparison between the common method and the new method is given. It is concluded that the minimum allowed value of IFOV of rosette scanning is over estimated by the common method while this value can be calculated accurately with the new method.展开更多
The law of variation of deep rock stress in gravitational and tectonic stress fields is analyzed based on the Hoek-Brown strength criterion. In the gravitational stress field,the rocks in the shallow area are in an el...The law of variation of deep rock stress in gravitational and tectonic stress fields is analyzed based on the Hoek-Brown strength criterion. In the gravitational stress field,the rocks in the shallow area are in an elastic state and the deep,relatively soft rock may be in a plastic state. However,in the tectonic stress field,the relatively soft rock in the shallow area is in a plastic state and the deep rock in an elastic state. A method is proposed to estimate stress values in coal and soft rock based on in-situ measurements of hard rock. Our estimation method relates to the type of stress field and stress state. The equations of rock stress in various stress states are presented for the elastic,plastic and critical states. The critical state is a special stress state,which indicates the conversion of the elastic to the plastic state in the gravitational stress field and the conversion of the plastic to the elastic state in the tectonic stress field. Two cases stud-ies show that the estimation method is feasible.展开更多
A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay ...A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay arrivals of surface-bottom reflection and bottom-surface reflection intersect at the source depth. Two hydrophones deployed vertically with a certain interval are required at least. If the receiver depths are known, the pair of time delays can be used to estimate the source depth. With the proposed method the source depth can be estimated successfully in a moderate range in the deep ocean without complicated matched-field calculations in the simulations and experiments.展开更多
The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of ...The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of extended targets are investigated. It is demonstrated by simulations that the target length measured by the bistatic H RRP is more meaningful and accurate than that by the monostatic HRRP,though the monostatic H RRP has been well developed and widely used in target recognizing and classification. The estimation results of a cone shaped target are present and compared at the end of the paper. To assure the reliability of the simulation,the bistatic H RRP is obtained through the scattering field data calculated by a fullwave numerical method,FE-BI-MLFMA.展开更多
In recent years,great breakthroughs have been made in the exploration and development of natural gas in deep coal-rock reservoirs in Junggar,Ordos and other basins in China.In view of the inconsistency between the ind...In recent years,great breakthroughs have been made in the exploration and development of natural gas in deep coal-rock reservoirs in Junggar,Ordos and other basins in China.In view of the inconsistency between the industrial and academic circles on this new type of unconventional natural gas,this paper defines the concept of"coal-rock gas"on the basis of previous studies,and systematically analyzes its characteristics of occurrence state,transport and storage form,differential accumulation,and development law.Coal-rock gas,geologically unlike coalbed methane in the traditional sense,occurs in both free and adsorbed states,with free state in abundance.It is generated and stored in the same set of rocks through short distance migration,occasionally with the accumulation from other sources.Moreover,coal rock develops cleat fractures,and the free gas accumulates differentially.The coal-rock gas reservoirs deeper than 2000 m are high in pressure,temperature,gas content,gas saturation,and free-gas content.In terms of development,similar to shale gas and tight gas,coal-rock gas can be exploited by natural formation energy after the reservoirs connectivity is improved artificially,that is,the adsorbed gas is desorbed due to pressure drop after the high-potential free gas is recovered,so that the free gas and adsorbed gas are produced in succession for a long term without water drainage for pressure drop.According to buried depth,coal rank,pressure coefficient,reserves scale,reserves abundance and gas well production,the classification criteria and reserves/resources estimation method of coal-rock gas are presented.It is preliminarily estimated that the coal-rock gas in place deeper than 2000 m in China exceeds 30×10^(12)m^(3),indicating an important strategic resource for the country.The Ordos,Sichuan,Junggar and Bohai Bay basins are favorable areas for large-scale enrichment of coal-rock gas.The paper summarizes the technical and management challenges and points out the research directions,laying a foundation for the management,exploration,and development of coal-rock gas in China.展开更多
In recent years,demands for car transportation by a ship have been increasing with favorable economic conditions in auto sector,and the need of a pure car carrier(PCC) has grown quickly.A PCC needs huge parking space ...In recent years,demands for car transportation by a ship have been increasing with favorable economic conditions in auto sector,and the need of a pure car carrier(PCC) has grown quickly.A PCC needs huge parking space but smaller displacement since a car is comparatively light for its volume.As a result,almost all PCCs have wide breadth,shallow draft and huge structure above the water surface.These features cause some technical issues of a PCC,like lack of stability,effect of strong winds on its resistance,difficulty of course keeping in rough seas,difficulty of berthing in strong winds,and so on.To overcome these technical issues,one of the authors has proposed a new concept for a PCC.This is a trimaran PCC which has very limited transverse bulkheads in the center hull by using two side hulls as fenders.In the present research,wind forces acting on a scale model of the trimaran PCC were measured in the towing tank with a wind generator at Osaka Prefecture University.Furthermore,in order to clarify the characteristics of wind pressure on the trimaran,height and width of tunnels which are between a main hull and side hulls were changed.And then,in order to imitate a real ship,we used wind reduction technology of corner-cut design for accommodation house of the ship.Moreover,the wind pressure acting on the trimaran was compared with that on a mono-hull PCC.Using these experimental and theoretical results,an estimation method of wind pressure acting on the trimaran PCC is deduced.展开更多
With the recent advent of Intelligent Transporta- tion Systems （ITS）, and their associated data collection and archiving capabilities, there is now a rich data source for transportation professionals to develop capa...With the recent advent of Intelligent Transporta- tion Systems （ITS）, and their associated data collection and archiving capabilities, there is now a rich data source for transportation professionals to develop capacity values for their own jurisdictions. Unfortunately, there is no consensus on the best approach for estimating capacity from ITS data. The motivation of this paper is to compare and contrast four of the most popular capacity estimation techniques in terms of （1） data requirements, （2） modeling effort required, （3） esti- mated parameter values, （4） theoretical background, and （5） statistical differences across time and over geographically dispersed locations. Specifically, the first method is the maximum observed value, the second is a standard funda- mental diagram curve fitting approach using the popular Van Aerde model, the third method uses the breakdown identifi- cation approach, and the fourth method is the survival prob- ability based on product limit method. These four approaches were tested on two test beds： one is located in San Diego, California, U.S., and has data from 112 work days; the other is located in Shanghai, China, and consists of 81 work days. It was found that, irrespective of the estimation methodology and the definition of capacity, the estimated capacity can vary considerably over time. The second finding was that, as ex- pected, the different approaches yielded different capacity results. These estimated capacities varied by as much as 26 % at the San Diego test site and by 34 % at the Shanghai test site. It was also found that each of the methodologies has advantages and disadvantages, and the best method will be the function of the available data, the application, and the goals of the modeler. Consequently, it is critical for users of automatic capacity estimation techniques, which utilize ITS data, to understand the underlying assumptions of each of the different approaches.展开更多
Nowadays,mobile operators in China mainland are facing fierce competition from one to another,and their focus of customer competition has,in general,shifted from public to corporate customers.One big challenge in corp...Nowadays,mobile operators in China mainland are facing fierce competition from one to another,and their focus of customer competition has,in general,shifted from public to corporate customers.One big challenge in corporate customer management is how to identify fake corporate members and potential corporate members from corporate customers.In this study,we have proposed an identification method that combines the rule-based and probabilistic methods.Through this method,fake corporate members can be eliminated and external potential members can be mined.The experimental results based on the data obtained from a local mobile operator revealed that the proposed method can effectively and efficiently identify fake and potential corporate members.The proposed method can be used to improve the management of corporate customers.展开更多
文摘The methods of estimating the minimum allowed value of IFOV (instantaneous field of view) of the detector in a rosette scan system are investigated. The common method for the estimation of IFOV is described. A new method which uses the maximum distance between two neighboring petals as the estimated value of IFOV is developed and a comparison between the common method and the new method is given. It is concluded that the minimum allowed value of IFOV of rosette scanning is over estimated by the common method while this value can be calculated accurately with the new method.
基金Projects 40272114 and 40572160 supported by the National Natural Science Foundation of China
文摘The law of variation of deep rock stress in gravitational and tectonic stress fields is analyzed based on the Hoek-Brown strength criterion. In the gravitational stress field,the rocks in the shallow area are in an elastic state and the deep,relatively soft rock may be in a plastic state. However,in the tectonic stress field,the relatively soft rock in the shallow area is in a plastic state and the deep rock in an elastic state. A method is proposed to estimate stress values in coal and soft rock based on in-situ measurements of hard rock. Our estimation method relates to the type of stress field and stress state. The equations of rock stress in various stress states are presented for the elastic,plastic and critical states. The critical state is a special stress state,which indicates the conversion of the elastic to the plastic state in the gravitational stress field and the conversion of the plastic to the elastic state in the tectonic stress field. Two cases stud-ies show that the estimation method is feasible.
基金Supported by the National Natural Science Foundation of China under Grant No 11174235
文摘A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay arrivals of surface-bottom reflection and bottom-surface reflection intersect at the source depth. Two hydrophones deployed vertically with a certain interval are required at least. If the receiver depths are known, the pair of time delays can be used to estimate the source depth. With the proposed method the source depth can be estimated successfully in a moderate range in the deep ocean without complicated matched-field calculations in the simulations and experiments.
基金Supported by the National Natural Science Fundation of China(61001192)
文摘The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of extended targets are investigated. It is demonstrated by simulations that the target length measured by the bistatic H RRP is more meaningful and accurate than that by the monostatic HRRP,though the monostatic H RRP has been well developed and widely used in target recognizing and classification. The estimation results of a cone shaped target are present and compared at the end of the paper. To assure the reliability of the simulation,the bistatic H RRP is obtained through the scattering field data calculated by a fullwave numerical method,FE-BI-MLFMA.
基金Supported by the Prospective and Basic Research Project of PetroChina(2021DJ23)。
文摘In recent years,great breakthroughs have been made in the exploration and development of natural gas in deep coal-rock reservoirs in Junggar,Ordos and other basins in China.In view of the inconsistency between the industrial and academic circles on this new type of unconventional natural gas,this paper defines the concept of"coal-rock gas"on the basis of previous studies,and systematically analyzes its characteristics of occurrence state,transport and storage form,differential accumulation,and development law.Coal-rock gas,geologically unlike coalbed methane in the traditional sense,occurs in both free and adsorbed states,with free state in abundance.It is generated and stored in the same set of rocks through short distance migration,occasionally with the accumulation from other sources.Moreover,coal rock develops cleat fractures,and the free gas accumulates differentially.The coal-rock gas reservoirs deeper than 2000 m are high in pressure,temperature,gas content,gas saturation,and free-gas content.In terms of development,similar to shale gas and tight gas,coal-rock gas can be exploited by natural formation energy after the reservoirs connectivity is improved artificially,that is,the adsorbed gas is desorbed due to pressure drop after the high-potential free gas is recovered,so that the free gas and adsorbed gas are produced in succession for a long term without water drainage for pressure drop.According to buried depth,coal rank,pressure coefficient,reserves scale,reserves abundance and gas well production,the classification criteria and reserves/resources estimation method of coal-rock gas are presented.It is preliminarily estimated that the coal-rock gas in place deeper than 2000 m in China exceeds 30×10^(12)m^(3),indicating an important strategic resource for the country.The Ordos,Sichuan,Junggar and Bohai Bay basins are favorable areas for large-scale enrichment of coal-rock gas.The paper summarizes the technical and management challenges and points out the research directions,laying a foundation for the management,exploration,and development of coal-rock gas in China.
基金supported by the Sasakawa Scientific Research Grant from the Japan Science Society
文摘In recent years,demands for car transportation by a ship have been increasing with favorable economic conditions in auto sector,and the need of a pure car carrier(PCC) has grown quickly.A PCC needs huge parking space but smaller displacement since a car is comparatively light for its volume.As a result,almost all PCCs have wide breadth,shallow draft and huge structure above the water surface.These features cause some technical issues of a PCC,like lack of stability,effect of strong winds on its resistance,difficulty of course keeping in rough seas,difficulty of berthing in strong winds,and so on.To overcome these technical issues,one of the authors has proposed a new concept for a PCC.This is a trimaran PCC which has very limited transverse bulkheads in the center hull by using two side hulls as fenders.In the present research,wind forces acting on a scale model of the trimaran PCC were measured in the towing tank with a wind generator at Osaka Prefecture University.Furthermore,in order to clarify the characteristics of wind pressure on the trimaran,height and width of tunnels which are between a main hull and side hulls were changed.And then,in order to imitate a real ship,we used wind reduction technology of corner-cut design for accommodation house of the ship.Moreover,the wind pressure acting on the trimaran was compared with that on a mono-hull PCC.Using these experimental and theoretical results,an estimation method of wind pressure acting on the trimaran PCC is deduced.
文摘With the recent advent of Intelligent Transporta- tion Systems （ITS）, and their associated data collection and archiving capabilities, there is now a rich data source for transportation professionals to develop capacity values for their own jurisdictions. Unfortunately, there is no consensus on the best approach for estimating capacity from ITS data. The motivation of this paper is to compare and contrast four of the most popular capacity estimation techniques in terms of （1） data requirements, （2） modeling effort required, （3） esti- mated parameter values, （4） theoretical background, and （5） statistical differences across time and over geographically dispersed locations. Specifically, the first method is the maximum observed value, the second is a standard funda- mental diagram curve fitting approach using the popular Van Aerde model, the third method uses the breakdown identifi- cation approach, and the fourth method is the survival prob- ability based on product limit method. These four approaches were tested on two test beds： one is located in San Diego, California, U.S., and has data from 112 work days; the other is located in Shanghai, China, and consists of 81 work days. It was found that, irrespective of the estimation methodology and the definition of capacity, the estimated capacity can vary considerably over time. The second finding was that, as ex- pected, the different approaches yielded different capacity results. These estimated capacities varied by as much as 26 % at the San Diego test site and by 34 % at the Shanghai test site. It was also found that each of the methodologies has advantages and disadvantages, and the best method will be the function of the available data, the application, and the goals of the modeler. Consequently, it is critical for users of automatic capacity estimation techniques, which utilize ITS data, to understand the underlying assumptions of each of the different approaches.
基金supported by the Youth Research and Innovation Program in Beijing University of Posts and Telecommunications under Grants No. 2012RC1006,No. 2012RC1008the National Key Basic Research Program of China (973 Program) under Grant No.2012CB315805and the National Natural Science Foundation of China under Grant No.71172135
文摘Nowadays,mobile operators in China mainland are facing fierce competition from one to another,and their focus of customer competition has,in general,shifted from public to corporate customers.One big challenge in corporate customer management is how to identify fake corporate members and potential corporate members from corporate customers.In this study,we have proposed an identification method that combines the rule-based and probabilistic methods.Through this method,fake corporate members can be eliminated and external potential members can be mined.The experimental results based on the data obtained from a local mobile operator revealed that the proposed method can effectively and efficiently identify fake and potential corporate members.The proposed method can be used to improve the management of corporate customers.
