Aiming at the load imbalance and poor scalability in single-tier Web server clusters, an efficient load balancing ap- proach is proposed for constructing an N-hierarchical （multi-tier） Web server cluster. In each la...Aiming at the load imbalance and poor scalability in single-tier Web server clusters, an efficient load balancing ap- proach is proposed for constructing an N-hierarchical （multi-tier） Web server cluster. In each layer, multiple load balancers are set to receive the user requests simultaneously, and different load bal- ancing algorithms are used to construct the high-scalable Web cluster system. At the same time, an improved load balancing al- gorithm is proposed, which can dynamically calculate weights according to the utilization of the server resources, and reasonably distribute the loads for each server according to the load status of the servers. The experimental results show that the proposed ap- proach can greatly decrease the load imbalance among the Web servers and reduce the response time of the entire Web cluster system.展开更多
During the past decade,rapid advances in wireless communication technologies have made it possible for users to access desired services using hand-held devices.Service providers have hosted multiple servers to ensure ...During the past decade,rapid advances in wireless communication technologies have made it possible for users to access desired services using hand-held devices.Service providers have hosted multiple servers to ensure seamless online services to end-users.To ensure the security of this online communication,researchers have proposed several multi-server authentication schemes incorporating various cryptographic primitives.Due to the low power and computational capacities of mobile devices,the hash-based multi-server authenticated key agreement schemes with offline Registration Server(RS)are the most efficient choice.Recently,Kumar-Om presented such a scheme and proved its security against all renowned attacks.However,we find that their scheme bears an incorrect login phase,and is unsafe to the trace attack,the Session-Specific Temporary Information Attack(SSTIA),and the Key Compromise Impersonation Attack(KCIA).In fact,all of the existing multi-server authentication schemes(hash-based with offline RS)do not withstand KCLA.To deal with this situation,we propose an improved hash-based multi-server authentication scheme(with offline RS).We analyze the security of the proposed scheme under the random oracle model and use the t4Automated Validation of Internet Security Protocols and Applications''(AVISPA)tool.The comparative analysis of communication overhead and computational complexity metrics shows the efficiency of the proposed scheme.展开更多
How to use Microsoft SQL(structured query language) Server efficiently on net is analyzed. And the key technology about how to use ADO to manage SQL server databases and their devices and how to remotely trigger off t...How to use Microsoft SQL(structured query language) Server efficiently on net is analyzed. And the key technology about how to use ADO to manage SQL server databases and their devices and how to remotely trigger off the SQL server database on net for improving query speed are mainly discussed in this paper.展开更多
In cloud data centers,the consolidation of workload is one of the phases during which the available hosts are allocated tasks.This phenomenon ensures that the least possible number of hosts is used without compromise ...In cloud data centers,the consolidation of workload is one of the phases during which the available hosts are allocated tasks.This phenomenon ensures that the least possible number of hosts is used without compromise in meeting the Service Level Agreement(SLA).To consolidate the workloads,the hosts are segregated into three categories:normal hosts,under-loaded hosts,and over-loaded hosts based on their utilization.It is to be noted that the identification of an extensively used host or underloaded host is challenging to accomplish.Thresh-old values were proposed in the literature to detect this scenario.The current study aims to improve the existing methods that choose the underloaded hosts,get rid of Virtual Machines(VMs)from them,andfinally place them in some other hosts.The researcher proposes a Host Resource Utilization Aware(HRUAA)Algorithm to detect those underloaded and place its virtual machines on different hosts in a vibrant Cloud environment.The mechanism presented in this study is contrasted with existing mechanisms empirically.The results attained from the study estab-lish that numerous hosts can be shut down,while at the same time,the user's workload requirement can also be met.The proposed method is energy-efficient in workload consolidation,saves cost and time,and leverages active hosts.展开更多
The manfully packaging the content of the web server for down loading is much inefficient.The paper introduced a Web server agent for packaging automitization, which makes self-organization of the content of the pages...The manfully packaging the content of the web server for down loading is much inefficient.The paper introduced a Web server agent for packaging automitization, which makes self-organization of the content of the pages and free the site administrator from the heavy burden of the manually packaging the web pages downloaded by web browsers. An example was illustrated to show the details of the solution, which was implemented in J2EE architecture.展开更多
The utilization of nuclear power will persist as a prominent energy source in the foreseeable future.However,it presents substantial challenges concerning waste disposal and the potential emission of untreated radioac...The utilization of nuclear power will persist as a prominent energy source in the foreseeable future.However,it presents substantial challenges concerning waste disposal and the potential emission of untreated radioactive substances,such as radioactive 129I and 131I.The transportation of radioactive iodine poses a significant threat to both the environment and human health.Nevertheless,effectively,rapidly removing iodine ion from water using porous adsorbents remains a crucial challenge.In this work,three kinds of multiple sites porous organic polymers(POPs,POP-1,POP-2,and POP-3)have been developed using a monomer pre-modification strategy for highly efficient and fast I_(3) absorption from water.It is found that the POPs exhibited exceptional performance in terms of I3 adsorption,achieving a top-performing adsorption capacity of 5.25 g g^(-1) and the fastest average adsorption rate(K_(80%)=4.25 g g^(-1) h^(-1))with POP-1.Moreover,POP-1 exhibited exceptional capacity for the removal of I3 fromflowing aqueous solutions,with 95%removal efficiency observed even at 0.0005 mol L^(-1).Such results indicate that this material has the potential to be utilized for the emergency preparation of potable water in areas contaminated with radioactive iodine.The adsorption process can be effectively characterized by the Freundlich model and the pseudo-second-order model.The exceptional I_(3) absorption capacity is primarily attributed to the incorporation of a substantial number of active adsorption sites,including bromine,carbonyl,and amide groups.展开更多
High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for t...High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for their use.Here,this issue is addressed by creating a composite ink that combines Pb_(2)Ru_(2)O_(6) and TiB_(2) using polysilazane(PSZ)as a binder.After direct writing and annealing the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film at 800℃ in air,the resulting thin film exhibits a low temperature coefficient of resistance(TCR)of only 281 ppm/℃ over a wide temperature range from 100℃ to 700℃,while also demonstrating high sensitivity with a gauge factor approaching 19.8.This exceptional performance is attributed to the intrinsic properties of Pb_(2)Ru_(2)O_(6),which has positive TCR at high temperature,and TiB2,which has negative TCR at high temperature.Combining these materials reduces the overall TCR of the film.Tests showed that the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film maintains stable strain responses and significant signal output even under varying temperature.These findings provide valuable insights for developing high-temperature strain sensors with low TCR and high sensitivity,highlighting their potential for applications in high-temperature strain measurements.展开更多
We study a novel replication mechanism to ensure service continuity against multiple simultaneous server failures.In this mechanism,each item represents a computing task and is replicated intoξ+1 servers for some int...We study a novel replication mechanism to ensure service continuity against multiple simultaneous server failures.In this mechanism,each item represents a computing task and is replicated intoξ+1 servers for some integerξ≥1,with workloads specified by the amount of required resources.If one or more servers fail,the affected workloads can be redirected to other servers that host replicas associated with the same item,such that the service is not interrupted by the failure of up toξservers.This requires that any feasible assignment algorithm must reserve some capacity in each server to accommodate the workload redirected from potential failed servers without overloading,and determining the optimal method for reserving capacity becomes a key issue.Unlike existing algorithms that assume that no two servers share replicas of more than one item,we first formulate capacity reservation for a general arbitrary scenario.Due to the combinatorial nature of this problem,finding the optimal solution is difficult.To this end,we propose a Generalized and Simple Calculating Reserved Capacity(GSCRC)algorithm,with a time complexity only related to the number of items packed in the server.In conjunction with GSCRC,we propose a robust replica packing algorithm with capacity optimization(RobustPack),which aims to minimize the number of servers hosting replicas and tolerate multiple server failures.Through theoretical analysis and experimental evaluations,we show that the RobustPack algorithm can achieve better performance.展开更多
Data privacy leakage has always been a critical concern in cloud-based Internet of Things(IoT)systems.Dynamic Symmetric Searchable Encryption(DSSE)with forward and backward privacy aims to address this issue by enabli...Data privacy leakage has always been a critical concern in cloud-based Internet of Things(IoT)systems.Dynamic Symmetric Searchable Encryption(DSSE)with forward and backward privacy aims to address this issue by enabling updates and retrievals of ciphertext on untrusted cloud server while ensuring data privacy.However,previous research on DSSE mostly focused on single keyword search,which limits its practical application in cloud-based IoT systems.Recently,Patranabis(NDSS 2021)[1]proposed a groundbreaking DSSE scheme for conjunctive keyword search.However,this scheme fails to effectively handle deletion operations in certain circumstances,resulting in inaccurate query results.Additionally,the scheme introduces unnecessary search overhead.To overcome these problems,we present CKSE,an efficient conjunctive keyword DSSE scheme.Our scheme improves the oblivious shared computation protocol used in the scheme of Patranabis,thus enabling a more comprehensive deletion functionality.Furthermore,we introduce a state chain structure to reduce the search overhead.Through security analysis and experimental evaluation,we demonstrate that our CKSE achieves more comprehensive deletion functionality while maintaining comparable search performance and security,compared to the oblivious dynamic cross-tags protocol of Patranabis.The combination of comprehensive functionality,high efficiency,and security makes our CKSE an ideal choice for deployment in cloud-based IoT systems.展开更多
The Internet of Things(IoT)and allied applications have made real-time responsiveness for massive devices over the Internet essential.Cloud-edge/fog ensembles handle such applications'computations.For Beyond 5 th ...The Internet of Things(IoT)and allied applications have made real-time responsiveness for massive devices over the Internet essential.Cloud-edge/fog ensembles handle such applications'computations.For Beyond 5 th Generation(B5G)communication paradigms,Edge Servers(ESs)must be placed within Information Communication Technology infrastructures to meet Quality of Service requirements like response time and resource utilisation.Due to the large number of Base Stations(BSs)and ESs and the possibility of significant variations in placing the ESs within the IoTs geographical expanse for optimising multiple objectives,the Edge Server Placement Problem(ESPP)is NP-hard.Thus,stochastic evolutionary metaheuristics are natural.This work addresses the ESPP using a Particle Swarm Optimization that initialises particles as BS positions within the geography to maintain the workload while scanning through all feasible sets of BSs as an encoded sequence.The Workload-Threshold Aware Sequence Encoding(WTASE)Scheme for ESPP provides the number of ESs to be deployed,similar to existing methodologies and exact locations for their placements without the overhead of maintaining a prohibitively large distance matrix.Simulation tests using open-source datasets show that the suggested technique improves ESs utilisation rate,workload balance,and average energy consumption by 36%,17%,and 32%,respectively,compared to prior works.展开更多
本文在AJAX理念的指导下,针对WebGIS的不足之处,设计与实现了城市交通矢量WebGIS原型系统。原型系统以ArcGIS Server WebADF框架为核心构建地图引擎,以AJAX开源引擎ExtJS作为前端辅助工具实现查询以及统计分析功能。试验表明,基于AJAX...本文在AJAX理念的指导下,针对WebGIS的不足之处,设计与实现了城市交通矢量WebGIS原型系统。原型系统以ArcGIS Server WebADF框架为核心构建地图引擎,以AJAX开源引擎ExtJS作为前端辅助工具实现查询以及统计分析功能。试验表明,基于AJAX的富客户端WebGIS架构减轻了服务器端的负载,提升了客户端的运行效率,更加高效地提供了Web地理信息服务。展开更多
ArcGIS Server是ESRI公司基于IT工业标准推出的企业级WebGIS应用平台,它支持GIS功能集中管理和多用户负载均衡。ArcGIS Server GIS服务器运行机制复杂,部署基于ArcGIS Server API开发的Web应用程序或Web服务程序,需要考虑Web服务器、GI...ArcGIS Server是ESRI公司基于IT工业标准推出的企业级WebGIS应用平台,它支持GIS功能集中管理和多用户负载均衡。ArcGIS Server GIS服务器运行机制复杂,部署基于ArcGIS Server API开发的Web应用程序或Web服务程序,需要考虑Web服务器、GIS服务器和数据库服务器的配置和部署。本文通过研究ArcGIS Server的分布式体系结构和GIS服务器的运行机制,同时根据可用的硬件和软件资源,采取合理的服务器配置策略,以达到合理利用资源和有效发挥系统性能的目的。展开更多
基金Supported by the National Natural Science Foundation of China(61073063,61173029,61272182 and 61173030)the Ocean Public Welfare Scientific Research Project of State Oceanic Administration of China(201105033)National Digital Ocean Key Laboratory Open Fund Projects(KLDO201306)
文摘Aiming at the load imbalance and poor scalability in single-tier Web server clusters, an efficient load balancing ap- proach is proposed for constructing an N-hierarchical （multi-tier） Web server cluster. In each layer, multiple load balancers are set to receive the user requests simultaneously, and different load bal- ancing algorithms are used to construct the high-scalable Web cluster system. At the same time, an improved load balancing al- gorithm is proposed, which can dynamically calculate weights according to the utilization of the server resources, and reasonably distribute the loads for each server according to the load status of the servers. The experimental results show that the proposed ap- proach can greatly decrease the load imbalance among the Web servers and reduce the response time of the entire Web cluster system.
文摘During the past decade,rapid advances in wireless communication technologies have made it possible for users to access desired services using hand-held devices.Service providers have hosted multiple servers to ensure seamless online services to end-users.To ensure the security of this online communication,researchers have proposed several multi-server authentication schemes incorporating various cryptographic primitives.Due to the low power and computational capacities of mobile devices,the hash-based multi-server authenticated key agreement schemes with offline Registration Server(RS)are the most efficient choice.Recently,Kumar-Om presented such a scheme and proved its security against all renowned attacks.However,we find that their scheme bears an incorrect login phase,and is unsafe to the trace attack,the Session-Specific Temporary Information Attack(SSTIA),and the Key Compromise Impersonation Attack(KCIA).In fact,all of the existing multi-server authentication schemes(hash-based with offline RS)do not withstand KCLA.To deal with this situation,we propose an improved hash-based multi-server authentication scheme(with offline RS).We analyze the security of the proposed scheme under the random oracle model and use the t4Automated Validation of Internet Security Protocols and Applications''(AVISPA)tool.The comparative analysis of communication overhead and computational complexity metrics shows the efficiency of the proposed scheme.
文摘How to use Microsoft SQL(structured query language) Server efficiently on net is analyzed. And the key technology about how to use ADO to manage SQL server databases and their devices and how to remotely trigger off the SQL server database on net for improving query speed are mainly discussed in this paper.
文摘In cloud data centers,the consolidation of workload is one of the phases during which the available hosts are allocated tasks.This phenomenon ensures that the least possible number of hosts is used without compromise in meeting the Service Level Agreement(SLA).To consolidate the workloads,the hosts are segregated into three categories:normal hosts,under-loaded hosts,and over-loaded hosts based on their utilization.It is to be noted that the identification of an extensively used host or underloaded host is challenging to accomplish.Thresh-old values were proposed in the literature to detect this scenario.The current study aims to improve the existing methods that choose the underloaded hosts,get rid of Virtual Machines(VMs)from them,andfinally place them in some other hosts.The researcher proposes a Host Resource Utilization Aware(HRUAA)Algorithm to detect those underloaded and place its virtual machines on different hosts in a vibrant Cloud environment.The mechanism presented in this study is contrasted with existing mechanisms empirically.The results attained from the study estab-lish that numerous hosts can be shut down,while at the same time,the user's workload requirement can also be met.The proposed method is energy-efficient in workload consolidation,saves cost and time,and leverages active hosts.
文摘The manfully packaging the content of the web server for down loading is much inefficient.The paper introduced a Web server agent for packaging automitization, which makes self-organization of the content of the pages and free the site administrator from the heavy burden of the manually packaging the web pages downloaded by web browsers. An example was illustrated to show the details of the solution, which was implemented in J2EE architecture.
基金support from the National Natural Science Foundation of China(No.22273016,22273017,22233006)Plan for Henan Province University Science and Technology Innovation Team(No.25IRTSTHN002)+1 种基金Young Backbone Teacher Training Program of Henan Province(2023GGJS036)the 111 project(No.D17007).
文摘The utilization of nuclear power will persist as a prominent energy source in the foreseeable future.However,it presents substantial challenges concerning waste disposal and the potential emission of untreated radioactive substances,such as radioactive 129I and 131I.The transportation of radioactive iodine poses a significant threat to both the environment and human health.Nevertheless,effectively,rapidly removing iodine ion from water using porous adsorbents remains a crucial challenge.In this work,three kinds of multiple sites porous organic polymers(POPs,POP-1,POP-2,and POP-3)have been developed using a monomer pre-modification strategy for highly efficient and fast I_(3) absorption from water.It is found that the POPs exhibited exceptional performance in terms of I3 adsorption,achieving a top-performing adsorption capacity of 5.25 g g^(-1) and the fastest average adsorption rate(K_(80%)=4.25 g g^(-1) h^(-1))with POP-1.Moreover,POP-1 exhibited exceptional capacity for the removal of I3 fromflowing aqueous solutions,with 95%removal efficiency observed even at 0.0005 mol L^(-1).Such results indicate that this material has the potential to be utilized for the emergency preparation of potable water in areas contaminated with radioactive iodine.The adsorption process can be effectively characterized by the Freundlich model and the pseudo-second-order model.The exceptional I_(3) absorption capacity is primarily attributed to the incorporation of a substantial number of active adsorption sites,including bromine,carbonyl,and amide groups.
基金the National Key Research and Development Program of China(Grant No.2021YFB2012100)the Major Science and Technology Projects in Fujian Province(Grant No.2023HZ021005)+1 种基金the Open Project Program of Fujian Key Laboratory of Special Intelligent Equipment Measurement and Control(Grant No.FJIES2023KF06)the Industry-University-Research Co-operation Fund of the Eighth Research Institute of China Aerospace Science and Technology Corporation(Grant No.SAST2023-061).
文摘High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for their use.Here,this issue is addressed by creating a composite ink that combines Pb_(2)Ru_(2)O_(6) and TiB_(2) using polysilazane(PSZ)as a binder.After direct writing and annealing the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film at 800℃ in air,the resulting thin film exhibits a low temperature coefficient of resistance(TCR)of only 281 ppm/℃ over a wide temperature range from 100℃ to 700℃,while also demonstrating high sensitivity with a gauge factor approaching 19.8.This exceptional performance is attributed to the intrinsic properties of Pb_(2)Ru_(2)O_(6),which has positive TCR at high temperature,and TiB2,which has negative TCR at high temperature.Combining these materials reduces the overall TCR of the film.Tests showed that the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film maintains stable strain responses and significant signal output even under varying temperature.These findings provide valuable insights for developing high-temperature strain sensors with low TCR and high sensitivity,highlighting their potential for applications in high-temperature strain measurements.
基金supported in part by the National Key R&D Program of China under No.2023YFB2703800the National Science Foundation of China under Grants U22B2027,62172297,62102262,61902276 and 62272311+3 种基金Tianjin Intelligent Manufacturing Special Fund Project under Grants 20211097the China Guangxi Science and Technology Plan Project(Guangxi Science and Technology Base and Talent Special Project)under Grant AD23026096(Application Number 2022AC20001)Henan Provincial Natural Science Foundation of China under Grant 622RC616CCF-Nsfocus Kunpeng Fund Project under Grants CCF-NSFOCUS202207。
文摘We study a novel replication mechanism to ensure service continuity against multiple simultaneous server failures.In this mechanism,each item represents a computing task and is replicated intoξ+1 servers for some integerξ≥1,with workloads specified by the amount of required resources.If one or more servers fail,the affected workloads can be redirected to other servers that host replicas associated with the same item,such that the service is not interrupted by the failure of up toξservers.This requires that any feasible assignment algorithm must reserve some capacity in each server to accommodate the workload redirected from potential failed servers without overloading,and determining the optimal method for reserving capacity becomes a key issue.Unlike existing algorithms that assume that no two servers share replicas of more than one item,we first formulate capacity reservation for a general arbitrary scenario.Due to the combinatorial nature of this problem,finding the optimal solution is difficult.To this end,we propose a Generalized and Simple Calculating Reserved Capacity(GSCRC)algorithm,with a time complexity only related to the number of items packed in the server.In conjunction with GSCRC,we propose a robust replica packing algorithm with capacity optimization(RobustPack),which aims to minimize the number of servers hosting replicas and tolerate multiple server failures.Through theoretical analysis and experimental evaluations,we show that the RobustPack algorithm can achieve better performance.
基金supported in part by the Major Science and Technology Projects in Yunnan Province(202202AD080013)King Khalid University for funding this work through Large Group Project under grant number RGP.2/373/45.
文摘Data privacy leakage has always been a critical concern in cloud-based Internet of Things(IoT)systems.Dynamic Symmetric Searchable Encryption(DSSE)with forward and backward privacy aims to address this issue by enabling updates and retrievals of ciphertext on untrusted cloud server while ensuring data privacy.However,previous research on DSSE mostly focused on single keyword search,which limits its practical application in cloud-based IoT systems.Recently,Patranabis(NDSS 2021)[1]proposed a groundbreaking DSSE scheme for conjunctive keyword search.However,this scheme fails to effectively handle deletion operations in certain circumstances,resulting in inaccurate query results.Additionally,the scheme introduces unnecessary search overhead.To overcome these problems,we present CKSE,an efficient conjunctive keyword DSSE scheme.Our scheme improves the oblivious shared computation protocol used in the scheme of Patranabis,thus enabling a more comprehensive deletion functionality.Furthermore,we introduce a state chain structure to reduce the search overhead.Through security analysis and experimental evaluation,we demonstrate that our CKSE achieves more comprehensive deletion functionality while maintaining comparable search performance and security,compared to the oblivious dynamic cross-tags protocol of Patranabis.The combination of comprehensive functionality,high efficiency,and security makes our CKSE an ideal choice for deployment in cloud-based IoT systems.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through the Large Research Project under grant number RGP2/603/46。
文摘The Internet of Things(IoT)and allied applications have made real-time responsiveness for massive devices over the Internet essential.Cloud-edge/fog ensembles handle such applications'computations.For Beyond 5 th Generation(B5G)communication paradigms,Edge Servers(ESs)must be placed within Information Communication Technology infrastructures to meet Quality of Service requirements like response time and resource utilisation.Due to the large number of Base Stations(BSs)and ESs and the possibility of significant variations in placing the ESs within the IoTs geographical expanse for optimising multiple objectives,the Edge Server Placement Problem(ESPP)is NP-hard.Thus,stochastic evolutionary metaheuristics are natural.This work addresses the ESPP using a Particle Swarm Optimization that initialises particles as BS positions within the geography to maintain the workload while scanning through all feasible sets of BSs as an encoded sequence.The Workload-Threshold Aware Sequence Encoding(WTASE)Scheme for ESPP provides the number of ESs to be deployed,similar to existing methodologies and exact locations for their placements without the overhead of maintaining a prohibitively large distance matrix.Simulation tests using open-source datasets show that the suggested technique improves ESs utilisation rate,workload balance,and average energy consumption by 36%,17%,and 32%,respectively,compared to prior works.
文摘本文在AJAX理念的指导下,针对WebGIS的不足之处,设计与实现了城市交通矢量WebGIS原型系统。原型系统以ArcGIS Server WebADF框架为核心构建地图引擎,以AJAX开源引擎ExtJS作为前端辅助工具实现查询以及统计分析功能。试验表明,基于AJAX的富客户端WebGIS架构减轻了服务器端的负载,提升了客户端的运行效率,更加高效地提供了Web地理信息服务。
文摘ArcGIS Server是ESRI公司基于IT工业标准推出的企业级WebGIS应用平台,它支持GIS功能集中管理和多用户负载均衡。ArcGIS Server GIS服务器运行机制复杂,部署基于ArcGIS Server API开发的Web应用程序或Web服务程序,需要考虑Web服务器、GIS服务器和数据库服务器的配置和部署。本文通过研究ArcGIS Server的分布式体系结构和GIS服务器的运行机制,同时根据可用的硬件和软件资源,采取合理的服务器配置策略,以达到合理利用资源和有效发挥系统性能的目的。
