A novel dynamic software allocation algorithm suitable for pervasive computing environments is proposed to minimize power consumption of mobile devices. Considering the power cost incurred by the computation, communic...A novel dynamic software allocation algorithm suitable for pervasive computing environments is proposed to minimize power consumption of mobile devices. Considering the power cost incurred by the computation, communication and migration of software components, a power consumption model of component assignments between a mobile device and a server is set up. Also, the mobility of components and the mobility relationships between components are taken into account in software allocation. By using network flow theory, the optimization problem of power conservation is transformed into the optimal bipartition problem of a flow network which can be partitioned by the max-flow rain-cut algorithm. Simulation results show that the proposed algorithm can save si^nificantlv more energy than existing algorithms.展开更多
The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytica...The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends.展开更多
In order to improve the energy efficiency of large-scale data centers, a virtual machine(VM) deployment algorithm called three-threshold energy saving algorithm(TESA), which is based on the linear relation between the...In order to improve the energy efficiency of large-scale data centers, a virtual machine(VM) deployment algorithm called three-threshold energy saving algorithm(TESA), which is based on the linear relation between the energy consumption and(processor) resource utilization, is proposed. In TESA, according to load, hosts in data centers are divided into four classes, that is,host with light load, host with proper load, host with middle load and host with heavy load. By defining TESA, VMs on lightly loaded host or VMs on heavily loaded host are migrated to another host with proper load; VMs on properly loaded host or VMs on middling loaded host are kept constant. Then, based on the TESA, five kinds of VM selection policies(minimization of migrations policy based on TESA(MIMT), maximization of migrations policy based on TESA(MAMT), highest potential growth policy based on TESA(HPGT), lowest potential growth policy based on TESA(LPGT) and random choice policy based on TESA(RCT)) are presented, and MIMT is chosen as the representative policy through experimental comparison. Finally, five research directions are put forward on future energy management. The results of simulation indicate that, as compared with single threshold(ST) algorithm and minimization of migrations(MM) algorithm, MIMT significantly improves the energy efficiency in data centers.展开更多
Baseband design and implementation for micro/pico base stations (mBS) in 5G ultra-dense network (UDN) is studied. Low cost is an essential requirement for mBS baseband in UDN. Digital baseband cost of ASIC/ASIP (...Baseband design and implementation for micro/pico base stations (mBS) in 5G ultra-dense network (UDN) is studied. Low cost is an essential requirement for mBS baseband in UDN. Digital baseband cost of ASIC/ASIP (Application Specific Integrated Circuit / Instruction-set processor) is of the most uncertainty in roBS system. However. the actual costs and hardware feasibility of the baseband are yet unknown to network deployers and researchers. In this paper, we studied the baseband hardware system design and implementation for low-cost roBS. We analyzed popular baseband algorithms and architectures for both full-digital and hybrid beamforming (BF) for UDN. We then proposed feasible chip-level solutions for the baseband with up to 128-antenna BS system, and estimated their implementation cost. Results show that among lull-digital BF algorithms, zero-forcing is a choice of high performance and low cost; for hybrid BF, 4×32 architecture (32 RF chains) provides good reduction in baseband cost with acceptable performance loss, thus it can be a preferable solution under low cost consider- ation. The proposed system planning method can also be used for the design of other related systems.展开更多
In orthogonal frequency division multiple access(OFDMA) based femtocell networks,the co-tier interference among femto base stations(FBS) becomes important in multiuser and densely deployed environment.In order to miti...In orthogonal frequency division multiple access(OFDMA) based femtocell networks,the co-tier interference among femto base stations(FBS) becomes important in multiuser and densely deployed environment.In order to mitigate the co-tier interference and enhance the system total throughput,this paper proposed a best effort spectrum allocation scheme based on the extension of graph theory.In the scheme,a controller was proposed to collect the channel state information(CSI)of all femtocell user equipments(FUEs) in a certain range.Then,the controller evaluated the signal-to-interference Ratio(SIR) of each FUE and determined the set of its interference neighbors.By calculating the received power matrix(RPM) among FUEs and building interference graph matrix(IGM),different spectrum resource blocks(RBs) were assigned to the users with interference relation,while users without interference relation shared the same RBs,which could increase the spectrum efficiency.Simulation results show that the proposed algorithm can significantly improve the RB usage efficiency compared with the basic graph coloring theory,and more than 80% improvement can be acquired in dense deployment scenario.Besides,the throughput of both cell edge macro user equipments(MUEs) and cell edge FUEs is guaranteed on the premise of low interference.展开更多
The potential role of formal structural optimization was investigated for designing foldable and deployable structures in this work.Shape-sizing nested optimization is a challenging design problem.Shape,represented by...The potential role of formal structural optimization was investigated for designing foldable and deployable structures in this work.Shape-sizing nested optimization is a challenging design problem.Shape,represented by the lengths and relative angles of elements,is critical to achieving smooth deployment to a desired span,while the section profiles of each element must satisfy structural dynamic performances in each deploying state.Dynamic characteristics of deployable structures in the initial state,the final state and also the middle deploying states are all crucial to the structural dynamic performances.The shape was represented by the nodal coordinates and the profiles of cross sections were represented by the diameters and thicknesses.SQP(sequential quadratic programming) method was used to explore the design space and identify the minimum mass solutions that satisfy kinematic and structural dynamic constraints.The optimization model and methodology were tested on the case-study of a deployable pantograph.This strategy can be easily extended to design a wide range of deployable structures,including deployable antenna structures,foldable solar sails,expandable bridges and retractable gymnasium roofs.展开更多
Submersible buoy systems are widely used for oceanographic research,ocean engineering and coastal defense.Severe sea environment has obvious effects on the dynamics of submersible buoy systems.Huge tension can occur a...Submersible buoy systems are widely used for oceanographic research,ocean engineering and coastal defense.Severe sea environment has obvious effects on the dynamics of submersible buoy systems.Huge tension can occur and may cause the snap of cables,especially during the deployment period.This paper studies the deployment dynamics of submersible buoy systems with numerical and experimental methods.By applying the lumped mass approach,a three-dimensional multi-body model of submersible buoy system is developed considering the hydrodynamic force,tension force and impact force between components of submersible buoy system and seabed.Numerical integration method is used to solve the differential equations.The simulation output includes tension force,trajectory,profile and dropping location and impact force of submersible buoys.In addition,the deployment experiment of a simplified submersible buoy model was carried out.The profile and different nodes' velocities of the submersible buoy are obtained.By comparing the results of the two methods,it is found that the numerical model well simulates the actual process and conditions of the experiment.The simulation results agree well with the results of the experiment such as gravity anchor's location and velocities of different nodes of the submersible buoy.The study results will help to understand the conditions of submersible buoy's deployment,operation and recovery,and can be used to guide the design and optimization of the system.展开更多
The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum mod...The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.展开更多
the Information-Centric Networking(ICN) paradigm is proved to have the advantages of decreasing data delivery latency, enhancing user mobility, etc. However, current implementations of ICN require changing the infrast...the Information-Centric Networking(ICN) paradigm is proved to have the advantages of decreasing data delivery latency, enhancing user mobility, etc. However, current implementations of ICN require changing the infrastructure of Internet, which hinders its deployment and development. Meanwhile, Software Defined Networking(SDN) emerges as a viable solution to facilitate the deployment of new network paradigm without disrupting production traffic by decoupling the control plane from data forwarding plane. In this paper, the essential properties which reflect ICN working principles are summarized, and a framework called SDICN is designed in accordance to the SDN philosophy. The algorithmic frameworks of SDICN which can satisfy the essential properties are designed based on the programmability and virtualization functions of SDN. Based on Open Flow and data center technology, a prototype of SDICN is implemented. By comparing the performance with the CCNx, the SDICN is proved to be feasibility and availability.展开更多
Aimed at the problem of unbalanced energy existed in sensor networks, the clustered method is employed to enhance the efficient utilization of limited energy resources of the deployed sensor nodes. In this paper, we d...Aimed at the problem of unbalanced energy existed in sensor networks, the clustered method is employed to enhance the efficient utilization of limited energy resources of the deployed sensor nodes. In this paper, we describe the network lifetime as a function of the communication and data aggregation energy consumption and analyze the lifetime of different transmission schemes in the homogeneous and heterogeneous sensor networks. The analysis carried out in this paper can provide the guidelines for network deployment and protocol design in the future applications.展开更多
A new passive method for automatic dis-covery and bcation of network failure is proposed. This method employs a passive measurement to collect infonmtion and events from network traffic, and em-ploys a rrodel-based re...A new passive method for automatic dis-covery and bcation of network failure is proposed. This method employs a passive measurement to collect infonmtion and events from network traffic, and em-ploys a rrodel-based reasoning system to detect and locate network faults. Measurement points are de-ployed in a backbone network to capture the traffic and then evaluate the Quality of Service (QoS) metrics of end-to-end IP conversations. A muting rrodel is al-so established for the observed network to simulate the attributes and activities of reuters and links. This muting model also deduces the muting path for each IP conversation, and thus the QoS metrics of IP con-versations are mapped into the metrics of paths. With the inforrmtion of shared links of overlapping paths and network torrography technique, the QoS metrics of links can also be estimated, and the poorly rated links are picked out as failure points. This method is imple-mented in a tool named FaultMan, which is deployed in a campus network. Test results have shown its availa-bility in rriddle-scale networks.展开更多
This paper describes the deployment optimization technology and the cross-layer design of a surveil-lance WSN system applied in relic protection.Facing the typical technical challenges in the applicationcontext of rel...This paper describes the deployment optimization technology and the cross-layer design of a surveil-lance WSN system applied in relic protection.Facing the typical technical challenges in the applicationcontext of relic protection,we firstly propose a deployment technology based on ant colony optimization al-gorithm(DT-ACO)to overcome the difficulties in communication connectivity and sensing coverage.Meanwhile,DT-ACO minimizes the overall cost of the system as much as possible.Secondly we proposea novel power-aware cross-layer scheme(PACS)to facilitate adjustable system lifetime and surveillanceaccuracy.The performance analysis shows that we achieve lower device cost,significant extension of thesystem lifetime and improvement on the data delivery rate compared with the traditional methods.展开更多
Deepwater deployment of offshore structures in different sea states was investigated. The whole deployment system was modeled as a lumped mass model, and discretization scheme for cable geometry and methodology for ca...Deepwater deployment of offshore structures in different sea states was investigated. The whole deployment system was modeled as a lumped mass model, and discretization scheme for cable geometry and methodology for calculating the internal and external force acting on deploying cable were presented. The deployment model suitable for the time-varying length of deploying cable was specified. The free-surface flow fields together with the ship motions were used to calculate dynamic tension in the deploying cable during deployment of the structure. The deployment of deep sea mining system which was a typical subsea working system was employed. Based on lumped mass analysis model and parameters of deep sea mining system, numerical simulations were performed, and dynamic load and dynamic amplification factor(DAF) with different cable parameters, deploying velocities and sea states were obtained. It is shown that cable parameters and amplitudes of ocean waves can significantly influence the dynamic load and DAF, and the time-varying natural period of deploying system is a dominant factor, while the effect of deploying velocity is not obvious.展开更多
With increasing deployment of Web services, the research on the dependability and availability of Web service composition becomes more and more active. Since unexpected faults of Web service composition may occur in d...With increasing deployment of Web services, the research on the dependability and availability of Web service composition becomes more and more active. Since unexpected faults of Web service composition may occur in different levels at runtime, log analysis as a typical data- driven approach for fault diagnosis is more applicable and scalable in various architectures. Considering the trend that more and more service logs are represented using XML or JSON format which has good flexibility and interoperability, fault classification problem of semi-structured logs is considered as a challenging issue in this area. However, most existing approaches focus on the log content analysis but ignore the structural information and lead to poor performance. To improve the accuracy of fault classification, we exploit structural similarity of log files and propose a similarity based Bayesian learning approach for semi-structured logs in this paper. Our solution estimates degrees of similarity among structural elements from heterogeneous log data, constructs combined Bayesian network (CBN), uses similarity based learning algorithm to compute probabilities in CBN, and classifies test log data into most probable fault categories based on the generated CBN. Experimental results show that our approach outperforms other learning approaches on structural log datasets.展开更多
Aortic valve stenosis is the most common valve disease in the western world. Over the past few years the number of aortic valve replacement (AVR) interventions has increased with outcomes that have been improved des...Aortic valve stenosis is the most common valve disease in the western world. Over the past few years the number of aortic valve replacement (AVR) interventions has increased with outcomes that have been improved despite increasing age of patients and increasing bur- den of comorbidities. However, despite such excellent results and its well-established position, conventional AVR has undergone great de- velopment over the previous two decades. Such progress, by way of less irtvasive incisions and use of new technologies, including tran- scatheter aortic valve implantation and sutureless valve prostheses, is intended to reduce the traumatic impact of the surgical procedure, thus fulfilling lower risk patients' expectations on the one hand, and extending the operability toward increasingly high-risk patients on the other. Sutureless and rapid deployment aortic valves are biological, pericardial prostheses that anchor within the aortic annulus with no more than three sutures. The sutureless prostheses, by avoiding the passage and the tying of the sutures, significantly reduce operative times and may improve outcomes. However, there is still a paucity of robust, evidence-based data on the role and performance of sutureless AVR. Therefore, strongest long-term data, randomized studies and registry data are required to adequately assess the durability and long-term outcomes of sutureless aortic valve replacement.展开更多
Femtocell is a promising technology for improving indoor coverage and offloading the macrocell.Femtocells tend to be densely deployed in populated areas such as the dormitories.However,the inter-tier interference seri...Femtocell is a promising technology for improving indoor coverage and offloading the macrocell.Femtocells tend to be densely deployed in populated areas such as the dormitories.However,the inter-tier interference seriously exists in the co-channel Densely Deployed Femtocell Network(DDFN).Since the Femtocell Access Points(FAPs) are randomly deployed by their customers,the interference cannot be predicted in advance.Meanwhile,new characteristics such as the short radius of femtocell and the small number of users lead to the inefficiency of the traditional frequency reuse algorithms such as Fractional Frequency Reuse(FFR).Aiming for the downlink interference coordination in the DDFN,in this paper,we propose a User-oriented Graph based Frequency Allocation(UGFA)algorithm.Firstly,we construct the interference graph for users in the network.Secondly,we study the conventional graph based resources allocation algorithm.Then an improved two steps graph based frequency allocation mechanism is proposed.Simulation results show that UGFA has a high frequency reuse ratio mean while guarantees a better throughput.展开更多
In cloud computing,the number of replicas and deployment strategy have extensive impacts on user's requirement and storage efficiency.Therefore,in this paper,a new definition of file access popularity according to...In cloud computing,the number of replicas and deployment strategy have extensive impacts on user's requirement and storage efficiency.Therefore,in this paper,a new definition of file access popularity according to users' preferences,and its prediction algorithm are provided to predict file access trend with historical data.Files are sorted by priority depending on their popularity.A mathematical model between file access popularity and the number of replicas is built so that the reliability is increased efficiently.Most importantly,we present an optimal strategy of dynamic replicas deployment based on the file access popularity strategy with the overall concern of nodes' performance and load condition.By this strategy,files with high priority will be deployed on nodes with better performance therefore higher quality of service is guaranteed.The strategy is realized in the Hadoop platform.Performance is compared with that of default strategy in Hadoop and CDRM strategy.The result shows that the proposed strategy can not only maintain the system load balance,but also supply better service performance,which is consistent with the theoretical analysis.展开更多
In light of demands for wireless monitoring and the characteristics of wireless channel,a complete deployment method containing channel survey,path loss estimation,and gradient grade of wireless relay nodes is propose...In light of demands for wireless monitoring and the characteristics of wireless channel,a complete deployment method containing channel survey,path loss estimation,and gradient grade of wireless relay nodes is proposed.It can be proved by experiments that under the premise of meeting the requirements of real-time and redundant-topology,the total number of relay nodes could be minimized by using the proposed method.展开更多
基金The National Natural Science Foundation of China(No60503041)the Science and Technology Commission of ShanghaiInternational Cooperation Project (No05SN07114)
文摘A novel dynamic software allocation algorithm suitable for pervasive computing environments is proposed to minimize power consumption of mobile devices. Considering the power cost incurred by the computation, communication and migration of software components, a power consumption model of component assignments between a mobile device and a server is set up. Also, the mobility of components and the mobility relationships between components are taken into account in software allocation. By using network flow theory, the optimization problem of power conservation is transformed into the optimal bipartition problem of a flow network which can be partitioned by the max-flow rain-cut algorithm. Simulation results show that the proposed algorithm can save si^nificantlv more energy than existing algorithms.
基金Project(60873081)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0787)supported by Program for New Century Excellent Talents in UniversityProject(11JJ1012)supported by the Natural Science Foundation of Hunan Province,China
文摘The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends.
基金Project(61272148) supported by the National Natural Science Foundation of ChinaProject(20120162110061) supported by the Doctoral Programs of Ministry of Education of China+1 种基金Project(CX2014B066) supported by the Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(2014zzts044) supported by the Fundamental Research Funds for the Central Universities,China
文摘In order to improve the energy efficiency of large-scale data centers, a virtual machine(VM) deployment algorithm called three-threshold energy saving algorithm(TESA), which is based on the linear relation between the energy consumption and(processor) resource utilization, is proposed. In TESA, according to load, hosts in data centers are divided into four classes, that is,host with light load, host with proper load, host with middle load and host with heavy load. By defining TESA, VMs on lightly loaded host or VMs on heavily loaded host are migrated to another host with proper load; VMs on properly loaded host or VMs on middling loaded host are kept constant. Then, based on the TESA, five kinds of VM selection policies(minimization of migrations policy based on TESA(MIMT), maximization of migrations policy based on TESA(MAMT), highest potential growth policy based on TESA(HPGT), lowest potential growth policy based on TESA(LPGT) and random choice policy based on TESA(RCT)) are presented, and MIMT is chosen as the representative policy through experimental comparison. Finally, five research directions are put forward on future energy management. The results of simulation indicate that, as compared with single threshold(ST) algorithm and minimization of migrations(MM) algorithm, MIMT significantly improves the energy efficiency in data centers.
基金supporting from National High Technical Research and Development Program of China(863 program)2014AA01A705 is sincerely acknowledged by authors
文摘Baseband design and implementation for micro/pico base stations (mBS) in 5G ultra-dense network (UDN) is studied. Low cost is an essential requirement for mBS baseband in UDN. Digital baseband cost of ASIC/ASIP (Application Specific Integrated Circuit / Instruction-set processor) is of the most uncertainty in roBS system. However. the actual costs and hardware feasibility of the baseband are yet unknown to network deployers and researchers. In this paper, we studied the baseband hardware system design and implementation for low-cost roBS. We analyzed popular baseband algorithms and architectures for both full-digital and hybrid beamforming (BF) for UDN. We then proposed feasible chip-level solutions for the baseband with up to 128-antenna BS system, and estimated their implementation cost. Results show that among lull-digital BF algorithms, zero-forcing is a choice of high performance and low cost; for hybrid BF, 4×32 architecture (32 RF chains) provides good reduction in baseband cost with acceptable performance loss, thus it can be a preferable solution under low cost consider- ation. The proposed system planning method can also be used for the design of other related systems.
基金supported by the National Key Technology R&D Program of China(2012ZX03001031-004)the Fundamental Research Funds for the Central Universities (BUPT 2013RC0111)
文摘In orthogonal frequency division multiple access(OFDMA) based femtocell networks,the co-tier interference among femto base stations(FBS) becomes important in multiuser and densely deployed environment.In order to mitigate the co-tier interference and enhance the system total throughput,this paper proposed a best effort spectrum allocation scheme based on the extension of graph theory.In the scheme,a controller was proposed to collect the channel state information(CSI)of all femtocell user equipments(FUEs) in a certain range.Then,the controller evaluated the signal-to-interference Ratio(SIR) of each FUE and determined the set of its interference neighbors.By calculating the received power matrix(RPM) among FUEs and building interference graph matrix(IGM),different spectrum resource blocks(RBs) were assigned to the users with interference relation,while users without interference relation shared the same RBs,which could increase the spectrum efficiency.Simulation results show that the proposed algorithm can significantly improve the RB usage efficiency compared with the basic graph coloring theory,and more than 80% improvement can be acquired in dense deployment scenario.Besides,the throughput of both cell edge macro user equipments(MUEs) and cell edge FUEs is guaranteed on the premise of low interference.
基金Project(030103) supported by the Weaponry Equipment Pre-Research Key Foundation of ChinaProject(69982009) supported by the National Natural Science Foundation of China
文摘The potential role of formal structural optimization was investigated for designing foldable and deployable structures in this work.Shape-sizing nested optimization is a challenging design problem.Shape,represented by the lengths and relative angles of elements,is critical to achieving smooth deployment to a desired span,while the section profiles of each element must satisfy structural dynamic performances in each deploying state.Dynamic characteristics of deployable structures in the initial state,the final state and also the middle deploying states are all crucial to the structural dynamic performances.The shape was represented by the nodal coordinates and the profiles of cross sections were represented by the diameters and thicknesses.SQP(sequential quadratic programming) method was used to explore the design space and identify the minimum mass solutions that satisfy kinematic and structural dynamic constraints.The optimization model and methodology were tested on the case-study of a deployable pantograph.This strategy can be easily extended to design a wide range of deployable structures,including deployable antenna structures,foldable solar sails,expandable bridges and retractable gymnasium roofs.
基金supported by the Program for Excellent University Talents in New Century (NCET-12-0500)the National Natural Science Foundation of China (No.51175484)+2 种基金the Science Foundation of Shandong Province (No.ZR2010EM052)the support of the Project 111 (No.B14028)the Key Ocean Engineering Laboratory of Shandong Province
文摘Submersible buoy systems are widely used for oceanographic research,ocean engineering and coastal defense.Severe sea environment has obvious effects on the dynamics of submersible buoy systems.Huge tension can occur and may cause the snap of cables,especially during the deployment period.This paper studies the deployment dynamics of submersible buoy systems with numerical and experimental methods.By applying the lumped mass approach,a three-dimensional multi-body model of submersible buoy system is developed considering the hydrodynamic force,tension force and impact force between components of submersible buoy system and seabed.Numerical integration method is used to solve the differential equations.The simulation output includes tension force,trajectory,profile and dropping location and impact force of submersible buoys.In addition,the deployment experiment of a simplified submersible buoy model was carried out.The profile and different nodes' velocities of the submersible buoy are obtained.By comparing the results of the two methods,it is found that the numerical model well simulates the actual process and conditions of the experiment.The simulation results agree well with the results of the experiment such as gravity anchor's location and velocities of different nodes of the submersible buoy.The study results will help to understand the conditions of submersible buoy's deployment,operation and recovery,and can be used to guide the design and optimization of the system.
基金Projects(50935002, 11002039) supported by the National Natural Science Foundation of ChinaProject(HIT.KLOF.2009062) supported by Key Laboratory Opening Funding of Aerospace Mechanism and Control Technology,Chinasupport by "111 Project" (Grant No.B07018)
文摘The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.
基金supported by the State Key Development Program for Basic Research of China under Grant No.2012CB315806National Natural Science Foundation of China(No.61379149,No.61402521 and No.61103225)+1 种基金Natural Science Foundation of Jiangsu(BK 20140070,BK20140068)Jiangsu Future Network Innovation Institute Research Project on Future Networks(BY2013095-1-06)
文摘the Information-Centric Networking(ICN) paradigm is proved to have the advantages of decreasing data delivery latency, enhancing user mobility, etc. However, current implementations of ICN require changing the infrastructure of Internet, which hinders its deployment and development. Meanwhile, Software Defined Networking(SDN) emerges as a viable solution to facilitate the deployment of new network paradigm without disrupting production traffic by decoupling the control plane from data forwarding plane. In this paper, the essential properties which reflect ICN working principles are summarized, and a framework called SDICN is designed in accordance to the SDN philosophy. The algorithmic frameworks of SDICN which can satisfy the essential properties are designed based on the programmability and virtualization functions of SDN. Based on Open Flow and data center technology, a prototype of SDICN is implemented. By comparing the performance with the CCNx, the SDICN is proved to be feasibility and availability.
基金Sponsored by the Shanghai Leading Academic Discipline Project (Grant No.S30108 and 08DZ2231100)Shanghai Education Committee (Grant No.09YZ33)+1 种基金Shanghai Science Committee(Grant No.08220510900)Key Lab Fund of SIMIT
文摘Aimed at the problem of unbalanced energy existed in sensor networks, the clustered method is employed to enhance the efficient utilization of limited energy resources of the deployed sensor nodes. In this paper, we describe the network lifetime as a function of the communication and data aggregation energy consumption and analyze the lifetime of different transmission schemes in the homogeneous and heterogeneous sensor networks. The analysis carried out in this paper can provide the guidelines for network deployment and protocol design in the future applications.
基金supported by the National Basic Research Program under Grant No. G1999032707the National High Technology Research and Development Program of China under Grant No. 2008AA01A303the Supporting Program of the"Eleventh Five-year Plan"for Sci & Tech Research of China under Grant No. 2008BAH37B03
文摘A new passive method for automatic dis-covery and bcation of network failure is proposed. This method employs a passive measurement to collect infonmtion and events from network traffic, and em-ploys a rrodel-based reasoning system to detect and locate network faults. Measurement points are de-ployed in a backbone network to capture the traffic and then evaluate the Quality of Service (QoS) metrics of end-to-end IP conversations. A muting rrodel is al-so established for the observed network to simulate the attributes and activities of reuters and links. This muting model also deduces the muting path for each IP conversation, and thus the QoS metrics of IP con-versations are mapped into the metrics of paths. With the inforrmtion of shared links of overlapping paths and network torrography technique, the QoS metrics of links can also be estimated, and the poorly rated links are picked out as failure points. This method is imple-mented in a tool named FaultMan, which is deployed in a campus network. Test results have shown its availa-bility in rriddle-scale networks.
基金Supported by the National High Technology Research and Development Programme of China ( No. 2006AA01Z215)the National Natural Science Foundation of China (No. 60572060+2 种基金 60533110)the National Basic Research Program of China (973)( No. 2006CB303000)the CAS Innovation Proiect (No. KGCX2-YW-110-3)
文摘This paper describes the deployment optimization technology and the cross-layer design of a surveil-lance WSN system applied in relic protection.Facing the typical technical challenges in the applicationcontext of relic protection,we firstly propose a deployment technology based on ant colony optimization al-gorithm(DT-ACO)to overcome the difficulties in communication connectivity and sensing coverage.Meanwhile,DT-ACO minimizes the overall cost of the system as much as possible.Secondly we proposea novel power-aware cross-layer scheme(PACS)to facilitate adjustable system lifetime and surveillanceaccuracy.The performance analysis shows that we achieve lower device cost,significant extension of thesystem lifetime and improvement on the data delivery rate compared with the traditional methods.
基金Project(51305463) supported by the National Natural Science Foundation of China
文摘Deepwater deployment of offshore structures in different sea states was investigated. The whole deployment system was modeled as a lumped mass model, and discretization scheme for cable geometry and methodology for calculating the internal and external force acting on deploying cable were presented. The deployment model suitable for the time-varying length of deploying cable was specified. The free-surface flow fields together with the ship motions were used to calculate dynamic tension in the deploying cable during deployment of the structure. The deployment of deep sea mining system which was a typical subsea working system was employed. Based on lumped mass analysis model and parameters of deep sea mining system, numerical simulations were performed, and dynamic load and dynamic amplification factor(DAF) with different cable parameters, deploying velocities and sea states were obtained. It is shown that cable parameters and amplitudes of ocean waves can significantly influence the dynamic load and DAF, and the time-varying natural period of deploying system is a dominant factor, while the effect of deploying velocity is not obvious.
基金This work is partially supported by National Basic Research Priorities Programme (No. 2013CB329502), Na-tional Natural Science Foundation of China (No. 61472468, 61502115), General Research Fund of Hong Kong (No. 417112), and Fundamental Research Funds for the Central Universities (No. 3262014T75, 3262015T20, 3262015T70, 3262016T31).
文摘With increasing deployment of Web services, the research on the dependability and availability of Web service composition becomes more and more active. Since unexpected faults of Web service composition may occur in different levels at runtime, log analysis as a typical data- driven approach for fault diagnosis is more applicable and scalable in various architectures. Considering the trend that more and more service logs are represented using XML or JSON format which has good flexibility and interoperability, fault classification problem of semi-structured logs is considered as a challenging issue in this area. However, most existing approaches focus on the log content analysis but ignore the structural information and lead to poor performance. To improve the accuracy of fault classification, we exploit structural similarity of log files and propose a similarity based Bayesian learning approach for semi-structured logs in this paper. Our solution estimates degrees of similarity among structural elements from heterogeneous log data, constructs combined Bayesian network (CBN), uses similarity based learning algorithm to compute probabilities in CBN, and classifies test log data into most probable fault categories based on the generated CBN. Experimental results show that our approach outperforms other learning approaches on structural log datasets.
文摘Aortic valve stenosis is the most common valve disease in the western world. Over the past few years the number of aortic valve replacement (AVR) interventions has increased with outcomes that have been improved despite increasing age of patients and increasing bur- den of comorbidities. However, despite such excellent results and its well-established position, conventional AVR has undergone great de- velopment over the previous two decades. Such progress, by way of less irtvasive incisions and use of new technologies, including tran- scatheter aortic valve implantation and sutureless valve prostheses, is intended to reduce the traumatic impact of the surgical procedure, thus fulfilling lower risk patients' expectations on the one hand, and extending the operability toward increasingly high-risk patients on the other. Sutureless and rapid deployment aortic valves are biological, pericardial prostheses that anchor within the aortic annulus with no more than three sutures. The sutureless prostheses, by avoiding the passage and the tying of the sutures, significantly reduce operative times and may improve outcomes. However, there is still a paucity of robust, evidence-based data on the role and performance of sutureless AVR. Therefore, strongest long-term data, randomized studies and registry data are required to adequately assess the durability and long-term outcomes of sutureless aortic valve replacement.
基金supported by the National Natural Science Foundation of China under Grant No.61372092the China National Science and Technology Major Projects on New Generation Broadband Wireless Mobile Communications Network under Grants No.2011ZX03005-004,No.2012ZX03001029-003,No.2012ZX03001008-003
文摘Femtocell is a promising technology for improving indoor coverage and offloading the macrocell.Femtocells tend to be densely deployed in populated areas such as the dormitories.However,the inter-tier interference seriously exists in the co-channel Densely Deployed Femtocell Network(DDFN).Since the Femtocell Access Points(FAPs) are randomly deployed by their customers,the interference cannot be predicted in advance.Meanwhile,new characteristics such as the short radius of femtocell and the small number of users lead to the inefficiency of the traditional frequency reuse algorithms such as Fractional Frequency Reuse(FFR).Aiming for the downlink interference coordination in the DDFN,in this paper,we propose a User-oriented Graph based Frequency Allocation(UGFA)algorithm.Firstly,we construct the interference graph for users in the network.Secondly,we study the conventional graph based resources allocation algorithm.Then an improved two steps graph based frequency allocation mechanism is proposed.Simulation results show that UGFA has a high frequency reuse ratio mean while guarantees a better throughput.
基金Supported by the National Natural Science Foundation of China(No.61170209,61272508,61202432,61370132,61370092)
文摘In cloud computing,the number of replicas and deployment strategy have extensive impacts on user's requirement and storage efficiency.Therefore,in this paper,a new definition of file access popularity according to users' preferences,and its prediction algorithm are provided to predict file access trend with historical data.Files are sorted by priority depending on their popularity.A mathematical model between file access popularity and the number of replicas is built so that the reliability is increased efficiently.Most importantly,we present an optimal strategy of dynamic replicas deployment based on the file access popularity strategy with the overall concern of nodes' performance and load condition.By this strategy,files with high priority will be deployed on nodes with better performance therefore higher quality of service is guaranteed.The strategy is realized in the Hadoop platform.Performance is compared with that of default strategy in Hadoop and CDRM strategy.The result shows that the proposed strategy can not only maintain the system load balance,but also supply better service performance,which is consistent with the theoretical analysis.
基金provided by the Natinal Basic Research Program of China(No.2012CB026000)
文摘In light of demands for wireless monitoring and the characteristics of wireless channel,a complete deployment method containing channel survey,path loss estimation,and gradient grade of wireless relay nodes is proposed.It can be proved by experiments that under the premise of meeting the requirements of real-time and redundant-topology,the total number of relay nodes could be minimized by using the proposed method.