Water supply is the primary element of an urban system. Due to rapid urbanization and water scarcity, maintaining a stable and safe water supply has become a challenge to many cities, whereas a large amount of water i...Water supply is the primary element of an urban system. Due to rapid urbanization and water scarcity, maintaining a stable and safe water supply has become a challenge to many cities, whereas a large amount of water is lost from the pipes of distribution systems. Water leakage is not only a waste of water resources, but also incurs great socio-economic costs. This article presents a comprehensive review on the potential water leakage control approaches and specifically discusses the benefits of each to environmental conservation. It is concluded that water leakage could be further reduced by improving leakage detection capability through a combination of predictive modeling and monitoring instruments, optimizing pipe maintenance strategy, and developing an instant pressure regulation system. The environment could benefit from these actions because of water savings and the reduction of energy consumption as well as greenhouse gas emissions.展开更多
Leakage control in deep oil and gas wells is challenging,often leading to increased costs.In this study,a low-density,high-pressure resistant and thermally stable epoxy resin(BEPD)was synthesized by ring opening of 2,...Leakage control in deep oil and gas wells is challenging,often leading to increased costs.In this study,a low-density,high-pressure resistant and thermally stable epoxy resin(BEPD)was synthesized by ring opening of 2,2-bis(4-epoxypropoxyphenyl)propane cured with 1,8-diaminonaphthalene.The material was thoroughly characterized using fourier-transform infrared spectroscopy,a universal testing machine,thermogravimetric analysis,and density testing.Comprehensive experimental and simulation analyses were conducted to evaluate BEPD's dispersion stability,its impact on the rheological properties of drilling fluid,and its effectiveness as a leakage control agent.It exhibits a high compressive strength(250.12 MPa)and a thermal decomposition temperature of 337.75℃,making it suitable for high-temperature environments.Its irregular particle shape ensures a strong bond with surrounding strata,forming a stable plugging layer.With a density of 1.09 g/cm^(3),BEPD disperses well in plugging slurry,reducing sedimentation.At dosages between 1%and 4%,it doesn't significantly affect the rheology of the slurry and effectively prevents sedimentation.BEPD particles effectively plugged fractures ranging from 1 to 4 mm,withstanding pressures up to 11.5 MPa.This performance is due to its unique particle size distribution,where larger particles act as bridges and smaller particles fill gaps,forming a dense plugging layer.BEPD shows potential as a highly effective material for improving leakage control in deep well applications.展开更多
Unaided authentication services provide the flexibility to login without being dependent on any additional device.The power of recording attack resilient unaided authentication services(RARUAS)is undeniable as,in some...Unaided authentication services provide the flexibility to login without being dependent on any additional device.The power of recording attack resilient unaided authentication services(RARUAS)is undeniable as,in some aspects,they are even capable of offering better security than the biometric based authentication systems.However,high login complexity of these RARUAS makes them far from usable in practice.The adopted information leakage control strategies have often been identified as the primary cause behind such high login complexities.Though recent proposals have made some significant efforts in designing a usable RARUAS by reducing its login complexity,most of them have failed to achieve the desired usability standard.In this paper,we have introduced a new notion of controlling the information leakage rate.By maintaining a good security standard,the introduced idea helps to reduce the login complexity of our proposed mechanism—named as Textual-Graphical Password-based Mechanism or TGPM,by a significant extent.Along with resisting the recording attack,TGPM also achieves a remarkable property of threat detection.To the best of our knowledge,TGPM is the first RARUAS,which can both prevent and detect the activities of the opportunistic recording attackers who can record the complete login activity of a genuine user for a few login sessions.Our study reveals that TGPM assures much higher session resiliency compared to the existing authentication services,having the same or even higher login complexities.Moreover,TGPM stores the password information in a distributed way and thus restricts the adversaries to learn the complete secret from a single compromised server.A thorough theoretical analysis has been performed to prove the strength of our proposal from both the security and usability perspectives.We have also conducted an experimental study to support the theoretical argument made on the usability standard of TGPM.展开更多
In this paper,a controllable leakage flux reverse salient permanent magnet synchronous motor(CLF-RSPMSM)is designed,which has the advantages of wide speed range and low irreversible demagnetization risk.Firstly,the pr...In this paper,a controllable leakage flux reverse salient permanent magnet synchronous motor(CLF-RSPMSM)is designed,which has the advantages of wide speed range and low irreversible demagnetization risk.Firstly,the principle of controllable leakage flux and reverse saliency effect is introduced,and the design of the rotor flux barrier is emphatically discussed.Secondly,multiple design variables are stratified by the comprehensive sensitivity method,and the main variables are screened out.Then the relationship between the main variables and the optimization goal is discussed according to the response surface diagram.Thirdly,a sequential nonlinear programming algorithm(SNP)is used to optimize the three optimization objectives comprehensively.Finally,the electromagnetic performance of the proposed motor is compared with the initial IPM motor,the mechanical strength of the proposed rotor is analyzed,and the results verify the effectiveness of the design and optimization method of the proposed motor.展开更多
基金supported by the National Natural Sciences Foundation of China(No.51309216)the Ministry of Sciences and Technology of the People’s Republic of China(No.2012ZX07408-002)
文摘Water supply is the primary element of an urban system. Due to rapid urbanization and water scarcity, maintaining a stable and safe water supply has become a challenge to many cities, whereas a large amount of water is lost from the pipes of distribution systems. Water leakage is not only a waste of water resources, but also incurs great socio-economic costs. This article presents a comprehensive review on the potential water leakage control approaches and specifically discusses the benefits of each to environmental conservation. It is concluded that water leakage could be further reduced by improving leakage detection capability through a combination of predictive modeling and monitoring instruments, optimizing pipe maintenance strategy, and developing an instant pressure regulation system. The environment could benefit from these actions because of water savings and the reduction of energy consumption as well as greenhouse gas emissions.
基金supported by the Open Fund of State Key Laboratory Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)(No.PLN2022-22,PLN2022-32)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(No.2020CX040102,2020CX040201)+1 种基金Special Projects of Central Government Guiding Development of Local Science and Technology,China(No.2023ZYD0033)Natural Science Foundation of Sichuan Province(No.2025ZNSFSC0377).
文摘Leakage control in deep oil and gas wells is challenging,often leading to increased costs.In this study,a low-density,high-pressure resistant and thermally stable epoxy resin(BEPD)was synthesized by ring opening of 2,2-bis(4-epoxypropoxyphenyl)propane cured with 1,8-diaminonaphthalene.The material was thoroughly characterized using fourier-transform infrared spectroscopy,a universal testing machine,thermogravimetric analysis,and density testing.Comprehensive experimental and simulation analyses were conducted to evaluate BEPD's dispersion stability,its impact on the rheological properties of drilling fluid,and its effectiveness as a leakage control agent.It exhibits a high compressive strength(250.12 MPa)and a thermal decomposition temperature of 337.75℃,making it suitable for high-temperature environments.Its irregular particle shape ensures a strong bond with surrounding strata,forming a stable plugging layer.With a density of 1.09 g/cm^(3),BEPD disperses well in plugging slurry,reducing sedimentation.At dosages between 1%and 4%,it doesn't significantly affect the rheology of the slurry and effectively prevents sedimentation.BEPD particles effectively plugged fractures ranging from 1 to 4 mm,withstanding pressures up to 11.5 MPa.This performance is due to its unique particle size distribution,where larger particles act as bridges and smaller particles fill gaps,forming a dense plugging layer.BEPD shows potential as a highly effective material for improving leakage control in deep well applications.
文摘Unaided authentication services provide the flexibility to login without being dependent on any additional device.The power of recording attack resilient unaided authentication services(RARUAS)is undeniable as,in some aspects,they are even capable of offering better security than the biometric based authentication systems.However,high login complexity of these RARUAS makes them far from usable in practice.The adopted information leakage control strategies have often been identified as the primary cause behind such high login complexities.Though recent proposals have made some significant efforts in designing a usable RARUAS by reducing its login complexity,most of them have failed to achieve the desired usability standard.In this paper,we have introduced a new notion of controlling the information leakage rate.By maintaining a good security standard,the introduced idea helps to reduce the login complexity of our proposed mechanism—named as Textual-Graphical Password-based Mechanism or TGPM,by a significant extent.Along with resisting the recording attack,TGPM also achieves a remarkable property of threat detection.To the best of our knowledge,TGPM is the first RARUAS,which can both prevent and detect the activities of the opportunistic recording attackers who can record the complete login activity of a genuine user for a few login sessions.Our study reveals that TGPM assures much higher session resiliency compared to the existing authentication services,having the same or even higher login complexities.Moreover,TGPM stores the password information in a distributed way and thus restricts the adversaries to learn the complete secret from a single compromised server.A thorough theoretical analysis has been performed to prove the strength of our proposal from both the security and usability perspectives.We have also conducted an experimental study to support the theoretical argument made on the usability standard of TGPM.
基金This work was supported by the National Natural Science Foundation of China under Grant no.52067008in part by the Plan Project of Jiangxi Province of P.R.China under grant no.GJJ160598 and 20181BAB206035,and in part by the Program of Qingjiang Excellent Young Talents.
文摘In this paper,a controllable leakage flux reverse salient permanent magnet synchronous motor(CLF-RSPMSM)is designed,which has the advantages of wide speed range and low irreversible demagnetization risk.Firstly,the principle of controllable leakage flux and reverse saliency effect is introduced,and the design of the rotor flux barrier is emphatically discussed.Secondly,multiple design variables are stratified by the comprehensive sensitivity method,and the main variables are screened out.Then the relationship between the main variables and the optimization goal is discussed according to the response surface diagram.Thirdly,a sequential nonlinear programming algorithm(SNP)is used to optimize the three optimization objectives comprehensively.Finally,the electromagnetic performance of the proposed motor is compared with the initial IPM motor,the mechanical strength of the proposed rotor is analyzed,and the results verify the effectiveness of the design and optimization method of the proposed motor.
