Aiming at mitigating multipath effect in dynamic global positioning system （GPS） satellite navigation applications, an approach based on channel blind equalization and real-time recursive least square （RLS） algori...Aiming at mitigating multipath effect in dynamic global positioning system （GPS） satellite navigation applications, an approach based on channel blind equalization and real-time recursive least square （RLS） algorithm is proposed, which is an application of the wireless communication channel equalization theory to GPS receiver tracking loops. The blind equalization mechanism builds upon the detection of the correlation distortion due to multipath channels; therefore an increase in the number of correlator channels is required compared with conventional GPS receivers. An adaptive estimator based on the real-time RLS algorithm is designed for dynamic estimation of multipath channel response. Then, the code and carrier phase receiver tracking errors are compensated by removing the estimated multipath components from the correlators＇ outputs. To demonstrate the capabilities of the proposed approach, this technique is integrated into a GPS software receiver connected to a navigation satellite signal simulator, thus simulations under controlled dynamic multipath scenarios can be carried out. Simulation results show that in a dynamic and fairly severe multipath environment, the proposed approach achieves simultaneously instantaneous accurate multipath channel estimation and significant multipath tracking errors reduction in both code delay and carrier phase.展开更多
Increasing urbanization in the cities of northern Mexico reflects a general trend to increased temperatures, so it is likely that heat waves amplify the frequency and intensity in urban centers, mainly located in arid...Increasing urbanization in the cities of northern Mexico reflects a general trend to increased temperatures, so it is likely that heat waves amplify the frequency and intensity in urban centers, mainly located in arid and semiarid as Mexicali city with extremely arid climate, very hot in summer and cold and rainy in winter. Mexicali, Baja California, Mexico is located at N32°38＇ and W115°20＇. The urban area is expanded over 14,890 hectares, with a population rise the 689,775. In the last four decades has experienced an accelerated industrial growth and mismatched land uses, for example： most of the industrial parks were established before the 1980 in what was the outskirts of the city, but nowadays practically are inside of the urban area contributing to the increase the urban temperature. The heat islands profile shows that are intensified in industrial areas as well as trade and services. The preliminary scenarios of climate change for Mexicali indicate that for the decade of 2080 the temperature will increase between 4.2℃ and 4.4℃. This paper addresses in a simulation context, an industrial and commercial city sector and their ability to implement urban heat island mitigation strategies. The simulation of this process requires several spatial analysis tools and specific knowledge about the processes that increase urban temperatures. In this work, only land use, land cover and buildings are considered. The proposed method takes into account the actual spatial organization to analyze trends for the proposed growth areas.展开更多
At present,shale gas exploration and development in China is faced with some problems,such as the imperfect evaluation system of reservoir effectiveness and the limitations of reservoir evaluation system on efficient d...At present,shale gas exploration and development in China is faced with some problems,such as the imperfect evaluation system of reservoir effectiveness and the limitations of reservoir evaluation system on efficient development of shale gas.In order to improve the content and the standard of reservoir evaluation,this paper analyzed the shortcomings and challenges in the static evaluation of shale gas reservoirs on the basis of existing reservoir evaluation,and established a method for evaluating shale gas reservoir effectiveness and a scheme for classifying pore systems.Then,the dynamic evaluation parameters after shale fracturing and their effects on drainage and production measures were discussed.In addition,the potential evaluation parameters of“automatic mitigating water blocking”were studied,and a comprehensive reservoir evaluation system of“staticedynamic”combination was established.And the following research results were obtained.First,new challenges to the shale gas reservoir evaluation are emerged as the lack of in-depth study on“reservoir effectiveness,dynamic evaluation parameter system after fracturing and drainage and production measures after fracturing”,which leads to the serious lag of existing shale gas reservoir evaluation system behind production.Second,the evaluation of reservoir effectiveness is mainly presented as the evaluation on the lower limit of effective porosity,and is embodied in the influence of clay bound water and unconnected pores on the development of shale gas.Third,the development of shale gas reservoir evaluation follows the trend of refining the static reservoir evaluation parameters,defining the potential evaluation indexes of“automatic mitigating water blocking”and establishing the reservoir comprehensive evaluation system of“staticedynamic”combination.Fourth,a post-frac dynamic evaluation system is determined for the potential evaluation indexes of“automatic mitigating water blocking”(e.g.,wettability,water imbibition retention capacity,water imbibition expansion mode,expansion rate,and water imbibition cracking capacity).Fifth,a reservoir evaluation idea is put forward that“static evaluation of shale gas reservoir is the foundation and postfrac dynamic evaluation is the complement”,and a comprehensive reservoir evaluation system is established of“staticedy-namic”combination suitable for the evaluation of marine shale gas reservoirs in China.展开更多
The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset fron...The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset frontal vehicle-to-vehicle collision. A unique 6-degree-of- freedom （6-DOF） vehicle dynamics/crash mathematical model and a simplified lumped mass occupant model are developed. The first model is used to define the vehicle body crash parameters and it integrates a vehicle dynamics model with a vehicle front-end structure model. The second model aims to predict the effect of VDCS on the kinematics of the occupant. It is shown from the numerical simulations that the vehicle dynamics/crash response and occupant behaviour can be captured and analysed quickly and accurately. Yurthermore, it is shown that the VDCS can affect the crash characteristics positively and the occupant behaviour is improved.展开更多
基金co-supported by National Natural Science Foundation of China (No. 61101075)the Pre-research Foundation (No. 9140A24040710HK0126)Fundament Research Funds for the Central Universities (YWF-11-02-176)
文摘Aiming at mitigating multipath effect in dynamic global positioning system （GPS） satellite navigation applications, an approach based on channel blind equalization and real-time recursive least square （RLS） algorithm is proposed, which is an application of the wireless communication channel equalization theory to GPS receiver tracking loops. The blind equalization mechanism builds upon the detection of the correlation distortion due to multipath channels; therefore an increase in the number of correlator channels is required compared with conventional GPS receivers. An adaptive estimator based on the real-time RLS algorithm is designed for dynamic estimation of multipath channel response. Then, the code and carrier phase receiver tracking errors are compensated by removing the estimated multipath components from the correlators＇ outputs. To demonstrate the capabilities of the proposed approach, this technique is integrated into a GPS software receiver connected to a navigation satellite signal simulator, thus simulations under controlled dynamic multipath scenarios can be carried out. Simulation results show that in a dynamic and fairly severe multipath environment, the proposed approach achieves simultaneously instantaneous accurate multipath channel estimation and significant multipath tracking errors reduction in both code delay and carrier phase.
文摘Increasing urbanization in the cities of northern Mexico reflects a general trend to increased temperatures, so it is likely that heat waves amplify the frequency and intensity in urban centers, mainly located in arid and semiarid as Mexicali city with extremely arid climate, very hot in summer and cold and rainy in winter. Mexicali, Baja California, Mexico is located at N32°38＇ and W115°20＇. The urban area is expanded over 14,890 hectares, with a population rise the 689,775. In the last four decades has experienced an accelerated industrial growth and mismatched land uses, for example： most of the industrial parks were established before the 1980 in what was the outskirts of the city, but nowadays practically are inside of the urban area contributing to the increase the urban temperature. The heat islands profile shows that are intensified in industrial areas as well as trade and services. The preliminary scenarios of climate change for Mexicali indicate that for the decade of 2080 the temperature will increase between 4.2℃ and 4.4℃. This paper addresses in a simulation context, an industrial and commercial city sector and their ability to implement urban heat island mitigation strategies. The simulation of this process requires several spatial analysis tools and specific knowledge about the processes that increase urban temperatures. In this work, only land use, land cover and buildings are considered. The proposed method takes into account the actual spatial organization to analyze trends for the proposed growth areas.
基金supported by the National Natural Science Foundation of China"Characterization of the Nanopore Structure and Research on Seepage in Shale Reservoir"(No.:51674044)the Applied Basic Research Project of the Sichuan Province"Research on Intelligent Evaluation System for Key Production Zone of Marine Shale Gas(Provincial Significant Project)"(No.:2019YJ0346)+1 种基金the Significant Emerging Enginecring Project of the Sichuan Province"Research on the method of evaluating the effectiveness of fracturing the shak gas reservoir on the basis of fracturing fluid flow-back law"(No.:2019JDRC0095)the Overseas Expertise Introduction Project for Discipline Innovation(111 project)"Base of Overseas Expertise Introduction for Discipline Innovation of High-Efficiency Development of Deep-Layer Marine Shale Gas"(No.:D18016).
文摘At present,shale gas exploration and development in China is faced with some problems,such as the imperfect evaluation system of reservoir effectiveness and the limitations of reservoir evaluation system on efficient development of shale gas.In order to improve the content and the standard of reservoir evaluation,this paper analyzed the shortcomings and challenges in the static evaluation of shale gas reservoirs on the basis of existing reservoir evaluation,and established a method for evaluating shale gas reservoir effectiveness and a scheme for classifying pore systems.Then,the dynamic evaluation parameters after shale fracturing and their effects on drainage and production measures were discussed.In addition,the potential evaluation parameters of“automatic mitigating water blocking”were studied,and a comprehensive reservoir evaluation system of“staticedynamic”combination was established.And the following research results were obtained.First,new challenges to the shale gas reservoir evaluation are emerged as the lack of in-depth study on“reservoir effectiveness,dynamic evaluation parameter system after fracturing and drainage and production measures after fracturing”,which leads to the serious lag of existing shale gas reservoir evaluation system behind production.Second,the evaluation of reservoir effectiveness is mainly presented as the evaluation on the lower limit of effective porosity,and is embodied in the influence of clay bound water and unconnected pores on the development of shale gas.Third,the development of shale gas reservoir evaluation follows the trend of refining the static reservoir evaluation parameters,defining the potential evaluation indexes of“automatic mitigating water blocking”and establishing the reservoir comprehensive evaluation system of“staticedynamic”combination.Fourth,a post-frac dynamic evaluation system is determined for the potential evaluation indexes of“automatic mitigating water blocking”(e.g.,wettability,water imbibition retention capacity,water imbibition expansion mode,expansion rate,and water imbibition cracking capacity).Fifth,a reservoir evaluation idea is put forward that“static evaluation of shale gas reservoir is the foundation and postfrac dynamic evaluation is the complement”,and a comprehensive reservoir evaluation system is established of“staticedy-namic”combination suitable for the evaluation of marine shale gas reservoirs in China.
基金the Egyptian government and the Faculty of Engineering,Ain Shams University for supporting this research
文摘The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset frontal vehicle-to-vehicle collision. A unique 6-degree-of- freedom （6-DOF） vehicle dynamics/crash mathematical model and a simplified lumped mass occupant model are developed. The first model is used to define the vehicle body crash parameters and it integrates a vehicle dynamics model with a vehicle front-end structure model. The second model aims to predict the effect of VDCS on the kinematics of the occupant. It is shown from the numerical simulations that the vehicle dynamics/crash response and occupant behaviour can be captured and analysed quickly and accurately. Yurthermore, it is shown that the VDCS can affect the crash characteristics positively and the occupant behaviour is improved.
