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Sample records for dynamic load balancing

  1. Distributed dynamic load balancing in wireless networks

    NARCIS (Netherlands)

    S.C. Borst (Sem); I. Saniee; P.A. Whiting

    2007-01-01

    htmlabstractSpatial and temporal load variations, e.g. flash overloads and traffic hot spots that persist for minutes to hours, are intrinsic features of wireless networks, and give rise to potentially huge performance repercussions. Dynamic load balancing strategies provide a natural mechanism for

  2. Dynamic Load Balancing using Graphics Processors

    Directory of Open Access Journals (Sweden)

    R Mohan

    2014-04-01

    Full Text Available To get maximum performance on the many-core graphics processors, it is important to have an even balance of the workload so that all processing units contribute equally to the task at hand. This can be hard to achieve when the cost of a task is not known beforehand and when new sub-tasks are created dynamically during execution. Both the dynamic load balancing methods using Static task assignment and work stealing using deques are compared to see which one is more suited to the highly parallel world of graphics processors. They have been evaluated on the task of simulating a computer move against the human move, in the famous four in a row game. The experiments showed that synchronization can be very expensive, and those new methods which use graphics processor features wisely might be required.

  3. An efficient dynamic load balancing algorithm

    Science.gov (United States)

    Lagaros, Nikos D.

    2014-01-01

    In engineering problems, randomness and uncertainties are inherent. Robust design procedures, formulated in the framework of multi-objective optimization, have been proposed in order to take into account sources of randomness and uncertainty. These design procedures require orders of magnitude more computational effort than conventional analysis or optimum design processes since a very large number of finite element analyses is required to be dealt. It is therefore an imperative need to exploit the capabilities of computing resources in order to deal with this kind of problems. In particular, parallel computing can be implemented at the level of metaheuristic optimization, by exploiting the physical parallelization feature of the nondominated sorting evolution strategies method, as well as at the level of repeated structural analyses required for assessing the behavioural constraints and for calculating the objective functions. In this study an efficient dynamic load balancing algorithm for optimum exploitation of available computing resources is proposed and, without loss of generality, is applied for computing the desired Pareto front. In such problems the computation of the complete Pareto front with feasible designs only, constitutes a very challenging task. The proposed algorithm achieves linear speedup factors and almost 100% speedup factor values with reference to the sequential procedure.

  4. A Dynamic Load Balancing Mechanism for Distributed Systems

    Institute of Scientific and Technical Information of China (English)

    蓝有然

    1996-01-01

    It is desirable in a distributed system to have the system load balanced evenly among the nodes so that the mean job response time is minimized.In this paper,we present a dynamic load balancing mechanism(DLB).It adopts a cntralized approach and is network topology independent.The DLB mechanism employs a set of threscholds which are automatically adjusted as the system load changes.It also provides a simple mechanism for the system to switch between periodic and instantaneous load balancing policies with ease.The performance of the proposed algorithm is evaluated by intensive simulations for various parameters.Te simulation results show that the mean job response time in a system implementing DLB algorithm is significantly lower than the same system without load balancings.Furthermore,compared with a previously proposed algorithm,DLB algorithm demonstrates improved performance,especially when the system is heavily loaded and the load is unevenly distributed.

  5. A Framework for Distributed Dynamic Load Balancing in Heterogeneous Cluster

    Directory of Open Access Journals (Sweden)

    Neeraj Nehra

    2007-01-01

    Full Text Available Distributed Dynamic load balancing (DDLB is an important system function destined to distribute workload among available processors to improve throughput and/or execution times of parallel computer in Cluster Computing. Instead of balancing the load in cluster by process migration, or by moving an entire process to a less loaded computer, we make an attempt to balance load by splitting processes into separate jobs and then balance them to nodes. In order to get target, we use mobile agent (MA to distribute load among nodes in a cluster. In this study, a multi-agent framework for load balancing in heterogeneous cluster is given. Total load on node is calculated using queue length which is measured as the total number of processes in queue. We introduce types of agents along with policies needed to meet the requirements of the proposed load-balancing. Different metrics are used to compare load balancing mechanism with the existing message passing technology. The experiment is carried out on cluster of PC's divided into multiple LAN's using PMADE (Platform for Mobile agent distribution and execution. Preliminary experimental results demonstrated that the proposed framework is effective than the existing ones.

  6. Performance Comparision of Dynamic Load Balancing Algorithm in Cloud Computing

    Directory of Open Access Journals (Sweden)

    Yogita kaushik

    2016-08-01

    Full Text Available Cloud computing as a distributed paradigm, it has the latent to make over a large part of the Cooperative industry. In cloud computing it’s automatically describe more technologies like distributed computing, virtualization, software, web services and networking. We review the new cloud computing technologies, and indicate the main challenges for their development in future, among which load balancing problem stands out and attracts our attention Concept of load balancing in networking and in cloud environment both are widely different. Load balancing in networking its complete concern to avoid the problem of overloading and under loading in any sever networking cloud computing its complete different its involves different elements metrics such as security, reliability, throughput, tolerance, on demand services, cost etc. Through these elements we avoiding various node problem of distributing system where many services waiting for request and others are heavily loaded and through these its increase response time and degraded performance optimization. In this paper first we classify algorithms in static and dynamic. Then we analyzed the dynamic algorithms applied in dynamics environments in cloud. Through this paper we have been show compression of various dynamics algorithm in which we include honey bee algorithm, throttled algorithm, Biased random algorithm with different elements and describe how and which is best in cloud environment with different metrics mainly used elements are performance, resource utilization and minimum cost. Our main focus of paper is in the analyze various load balancing algorithms and their applicability in cloud environment.

  7. Monitoring dynamic loads on wind tunnel force balances

    Science.gov (United States)

    Ferris, Alice T.; White, William C.

    1989-01-01

    Two devices have been developed at NASA Langley to monitor the dynamic loads incurred during wind-tunnel testing. The Balance Dynamic Display Unit (BDDU), displays and monitors the combined static and dynamic forces and moments in the orthogonal axes. The Balance Critical Point Analyzer scales and sums each normalized signal from the BDDU to obtain combined dynamic and static signals that represent the dynamic loads at predefined high-stress points. The display of each instrument is a multiplex of six analog signals in a way that each channel is displayed sequentially as one-sixth of the horizontal axis on a single oscilloscope trace. Thus this display format permits the operator to quickly and easily monitor the combined static and dynamic level of up to six channels at the same time.

  8. A New Fuzzy Approach for Dynamic Load Balancing Algorithm

    CERN Document Server

    Karimi, Abbas; Jantan, Adznan b; Ramli, A R; Saripan, M Iqbal b

    2009-01-01

    Load balancing is the process of improving the Performance of a parallel and distributed system through is distribution of load among the processors [1-2]. Most of the previous work in load balancing and distributed decision making in general, do not effectively take into account the uncertainty and inconsistency in state information but in fuzzy logic, we have advantage of using crisps inputs. In this paper, we present a new approach for implementing dynamic load balancing algorithm with fuzzy logic, which can face to uncertainty and inconsistency of previous algorithms, further more our algorithm shows better response time than round robin and randomize algorithm respectively 30.84 percent and 45.45 percent.

  9. A New Fuzzy Approach for Dynamic Load Balancing Algorithm

    Directory of Open Access Journals (Sweden)

    Abbas Karimi

    2009-10-01

    Full Text Available Load balancing is the process of improving the Performance of a parallel and distributed system through is distribution of load among the processors [1-2]. Most of the previous work in load balancing and distributed decision making in general, do not effectively take into account the uncertainty and inconsistency in state information but in fuzzy logic, we have advantage of using crisps inputs. In this paper,we present a new approach for implementing dynamic load balancing algorithm with fuzzy logic, which can face to uncertainty and inconsistency of previous algorithms, further more our algorithm shows better response time than round robin and randomize algorithm respectively 30.84% and 45.45%.

  10. Internet traffic load balancing using dynamic hashing with flow volume

    Science.gov (United States)

    Jo, Ju-Yeon; Kim, Yoohwan; Chao, H. Jonathan; Merat, Francis L.

    2002-07-01

    Sending IP packets over multiple parallel links is in extensive use in today's Internet and its use is growing due to its scalability, reliability and cost-effectiveness. To maximize the efficiency of parallel links, load balancing is necessary among the links, but it may cause the problem of packet reordering. Since packet reordering impairs TCP performance, it is important to reduce the amount of reordering. Hashing offers a simple solution to keep the packet order by sending a flow over a unique link, but static hashing does not guarantee an even distribution of the traffic amount among the links, which could lead to packet loss under heavy load. Dynamic hashing offers some degree of load balancing but suffers from load fluctuations and excessive packet reordering. To overcome these shortcomings, we have enhanced the dynamic hashing algorithm to utilize the flow volume information in order to reassign only the appropriate flows. This new method, called dynamic hashing with flow volume (DHFV), eliminates unnecessary flow reassignments of small flows and achieves load balancing very quickly without load fluctuation by accurately predicting the amount of transferred load between the links. In this paper we provide the general framework of DHFV and address the challenges in implementing DHFV. We then introduce two algorithms of DHFV with different flow selection strategies and show their performances through simulation.

  11. Dynamic Load Balancing Strategies for Parallel Reacting Flow Simulations

    Science.gov (United States)

    Pisciuneri, Patrick; Meneses, Esteban; Givi, Peyman

    2014-11-01

    Load balancing in parallel computing aims at distributing the work as evenly as possible among the processors. This is a critical issue in the performance of parallel, time accurate, flow simulators. The constraint of time accuracy requires that all processes must be finished with their calculation for a given time step before any process can begin calculation of the next time step. Thus, an irregularly balanced compute load will result in idle time for many processes for each iteration and thus increased walltimes for calculations. Two existing, dynamic load balancing approaches are applied to the simplified case of a partially stirred reactor for methane combustion. The first is Zoltan, a parallel partitioning, load balancing, and data management library developed at the Sandia National Laboratories. The second is Charm++, which is its own machine independent parallel programming system developed at the University of Illinois at Urbana-Champaign. The performance of these two approaches is compared, and the prospects for their application to full 3D, reacting flow solvers is assessed.

  12. Node reserve mechanism (over dynamic load-balancing)

    Energy Technology Data Exchange (ETDEWEB)

    Muniz, Francisco Junqueira; Azevedo, Carlos Vicente Goulart de; Dalle, Hugo Moura, E-mail: muniz@cdtn.br, E-mail: cvga@cdtn.br, E-mail: dallehm@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    Multiple-Instruction Multi-Data (MIMD) distributed-memory processing systems (such as an IBM like set of PCs, connected by a communication device) are since long time commercially available and in use. But many Research Institutions still use them as a mono-user facility: they are much more cost effective if used as a (multi-user) shared resource. However, the use of MIMD machines as a shared resource is often limited due to lack of an efficient, easy-to-use and on hand dynamic load-balancing technique. This work describes the arrangements that were made to establish the interface between a mechanism of processing power availability (resource determined from a shared computer facility) and simultaneous users, demand for resources. The key point is to allow the application designer to ask for (at once) as many nodes as he needs (a multi-reserve mechanism). The system runs over Linux/X86 computing nodes (a cluster). In order to show the interface functionality, the startup module of a MCNP package was modified in such a way that the multi-reserve node mechanism together with a multi-user dynamic load-balancing approach could be used. Nodes set demand is an intrinsic feature of MCNP package. Such modified MCNP package was successfully run over a dynamic load-balancing system. (author)

  13. Performance analysis of dynamic load balancing algorithm for multiprocessor interconnection network

    Directory of Open Access Journals (Sweden)

    M.U. Bokhari

    2016-09-01

    Full Text Available Multiprocessor interconnection network have become powerful parallel computing system for real-time applications. Nowadays the many researchers posses studies on the dynamic load balancing in multiprocessor system. Load balancing is the method of dividing the total load among the processors of the distributed system to progress task's response time as well as resource utilization whereas ignoring a condition where few processors are overloaded or underloaded or moderately loaded. However, in dynamic load balancing algorithm presumes no priori information about behaviour of tasks or the global state of the system. There are numerous issues while designing an efficient dynamic load balancing algorithm that involves utilization of system, amount of information transferred among processors, selection of tasks for migration, load evaluation, comparison of load levels and many more. This paper enlightens the performance analysis on dynamic load balancing strategy (DLBS algorithm, used for hypercube network in multiprocessor system.

  14. Dynamic load balancing algorithm for molecular dynamics based on Voronoi cells domain decompositions

    Energy Technology Data Exchange (ETDEWEB)

    Fattebert, J.-L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Richards, D.F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glosli, J.N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-12-01

    We present a new algorithm for automatic parallel load balancing in classical molecular dynamics. It assumes a spatial domain decomposition of particles into Voronoi cells. It is a gradient method which attempts to minimize a cost function by displacing Voronoi sites associated with each processor/sub-domain along steepest descent directions. Excellent load balance has been obtained for quasi-2D and 3D practical applications, with up to 440·106 particles on 65,536 MPI tasks.

  15. Energy Efficient Geographical Load Balancing via Dynamic Deferral of Workload

    CERN Document Server

    Adnan, Muhammad Abdullah; Gupta, Rajesh

    2012-01-01

    With the increasing popularity of Cloud computing and Mobile computing, individuals, enterprises and research centers have started outsourcing their IT and computational needs to on-demand cloud services. Recently geographical load balancing techniques have been suggested for data centers hosting cloud computation in order to reduce energy cost by exploiting the electricity price differences across regions. However, these algorithms do not draw distinction among diverse requirements for responsiveness across various workloads. In this paper, we use the flexibility from the Service Level Agreements (SLAs) to differentiate among workloads under bounded latency requirements and propose a novel approach for cost savings for geographical load balancing. We investigate how much workload to be executed in each data center and how much workload to be delayed and migrated to other data centers for energy saving while meeting deadlines. We present an offline formulation for geographical load balancing problem with dyna...

  16. Contribution of static and dynamic load balancing in a real-time distributed air defence simulation

    CSIR Research Space (South Africa)

    Duvenhage, B

    2008-05-01

    Full Text Available and Dynamic Load Balancing In A Real-Time Distributed Air Defence Simulation Mr Bernardt Duvenhage; Mr Jan J. Nel Council for Scientific and Industrial Research (CSIR) bduvenhage@csir.co.za, cnel@csir.co.za Abstract. Simulations with a large number... system. The measure to which dynamic load balancing could further enhance the performance is then explored. Such knowledge forms the basis for further load balance research. 1. INTRODUCTION The South African Council for Scientific and Industrial...

  17. Dynamic load balance scheme for the DSMC algorithm

    Science.gov (United States)

    Li, Jin; Geng, Xiangren; Jiang, Dingwu; Chen, Jianqiang

    2014-12-01

    The direct simulation Monte Carlo (DSMC) algorithm, devised by Bird, has been used over a wide range of various rarified flow problems in the past 40 years. While the DSMC is suitable for the parallel implementation on powerful multi-processor architecture, it also introduces a large load imbalance across the processor array, even for small examples. The load imposed on a processor by a DSMC calculation is determined to a large extent by the total of simulator particles upon it. Since most flows are impulsively started with initial distribution of particles which is surely quite different from the steady state, the total of simulator particles will change dramatically. The load balance based upon an initial distribution of particles will break down as the steady state of flow is reached. The load imbalance and huge computational cost of DSMC has limited its application to rarefied or simple transitional flows. In this paper, by taking advantage of METIS, a software for partitioning unstructured graphs, and taking the total of simulator particles in each cell as a weight information, the repartitioning based upon the principle that each processor handles approximately the equal total of simulator particles has been achieved. The computation must pause several times to renew the total of simulator particles in each processor and repartition the whole domain again. Thus the load balance across the processors array holds in the duration of computation. The parallel efficiency can be improved effectively. The benchmark solution of a cylinder submerged in hypersonic flow has been simulated numerically. Besides, hypersonic flow past around a complex wing-body configuration has also been simulated. The results have displayed that, for both of cases, the computational time can be reduced by about 50%.

  18. Dynamic load balance scheme for the DSMC algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jin; Geng, Xiangren; Jiang, Dingwu; Chen, Jianqiang [Computational Aerodynamics Institute of China Aerodynamics Research and Development Center, Mianyang, Sichuan, 621000 (China)

    2014-12-09

    The direct simulation Monte Carlo (DSMC) algorithm, devised by Bird, has been used over a wide range of various rarified flow problems in the past 40 years. While the DSMC is suitable for the parallel implementation on powerful multi-processor architecture, it also introduces a large load imbalance across the processor array, even for small examples. The load imposed on a processor by a DSMC calculation is determined to a large extent by the total of simulator particles upon it. Since most flows are impulsively started with initial distribution of particles which is surely quite different from the steady state, the total of simulator particles will change dramatically. The load balance based upon an initial distribution of particles will break down as the steady state of flow is reached. The load imbalance and huge computational cost of DSMC has limited its application to rarefied or simple transitional flows. In this paper, by taking advantage of METIS, a software for partitioning unstructured graphs, and taking the total of simulator particles in each cell as a weight information, the repartitioning based upon the principle that each processor handles approximately the equal total of simulator particles has been achieved. The computation must pause several times to renew the total of simulator particles in each processor and repartition the whole domain again. Thus the load balance across the processors array holds in the duration of computation. The parallel efficiency can be improved effectively. The benchmark solution of a cylinder submerged in hypersonic flow has been simulated numerically. Besides, hypersonic flow past around a complex wing-body configuration has also been simulated. The results have displayed that, for both of cases, the computational time can be reduced by about 50%.

  19. Dynamic Load Balancing Data Centric Storage for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Daesik Ko

    2010-11-01

    Full Text Available In this paper, a new data centric storage that is dynamically adapted to the work load changes is proposed. The proposed data centric storage distributes the load of hot spot areas to neighboring sensor nodes by using a multilevel grid technique. The proposed method is also able to use existing routing protocols such as GPSR (Greedy Perimeter Stateless Routing with small changes. Through simulation, the proposed method enhances the lifetime of sensor networks over one of the state-of-the-art data centric storages. We implement the proposed method based on an operating system for sensor networks, and evaluate the performance through running based on a simulation tool.

  20. A DYNAMIC LOAD BALANCING METHOD USING WORKSTATION PRIORITY

    Directory of Open Access Journals (Sweden)

    RAJKUMAR SHARMA,

    2011-04-01

    Full Text Available Load balancing is the task of distribution of application tasks to different processors in an efficient manner to minimize program execution time. It involves assigning work to each processor proportional to its computing power, hence minimizing the idle time and at the same time overload of work to the processor. In the Network of Workstations (NOWs based system, heterogeneity exists in processors, memory and networks parameters. In this paper, we introduce a workstation priority mechanism, which allots priority and an assignment factor to each workstation based on its computing power. The basic idea is to use this priority and assignment factor in allocating processors the tasks proportional to their performance. The major advantage of this technique is that all processors finish their tasks almost at same time, so as to minimize the occurrence of rebalancing state. This technique proves to be costeffective as the communication overheads are substantially reduced.

  1. Load Balancing Scientific Applications

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, Olga Tkachyshyn [Texas A & M Univ., College Station, TX (United States)

    2014-12-01

    The largest supercomputers have millions of independent processors, and concurrency levels are rapidly increasing. For ideal efficiency, developers of the simulations that run on these machines must ensure that computational work is evenly balanced among processors. Assigning work evenly is challenging because many large modern parallel codes simulate behavior of physical systems that evolve over time, and their workloads change over time. Furthermore, the cost of imbalanced load increases with scale because most large-scale scientific simulations today use a Single Program Multiple Data (SPMD) parallel programming model, and an increasing number of processors will wait for the slowest one at the synchronization points. To address load imbalance, many large-scale parallel applications use dynamic load balance algorithms to redistribute work evenly. The research objective of this dissertation is to develop methods to decide when and how to load balance the application, and to balance it effectively and affordably. We measure and evaluate the computational load of the application, and develop strategies to decide when and how to correct the imbalance. Depending on the simulation, a fast, local load balance algorithm may be suitable, or a more sophisticated and expensive algorithm may be required. We developed a model for comparison of load balance algorithms for a specific state of the simulation that enables the selection of a balancing algorithm that will minimize overall runtime.

  2. An Efficient and Scalable Content Based Dynamic Load Balancing Using Multiparameters on Load Aware Distributed Multi-Cluster Servers

    Directory of Open Access Journals (Sweden)

    T.N.Anitha

    2011-08-01

    Full Text Available Nowadays, more people are accessing the internet service for their daily activities. This dramatically increases requirement of server utilization, bandwidth requirement and resource availability. To serve this, cluster servers are used. But as number of users increases , several challenges are faced by cluster servers like congestion, delay in serving the request, load balancing ,heterogeneity and complexity of services. The existing dynamic load balancing does not scale up the performance in an Distributed heterogeneous environment. To avoid this, we propose an efficient and scalable content based Dynamic Load Balancing using multi parameters on load aware distributed multi-cluster servers. In this paper ,because of heterogeneity the Dynamic Load Balancing takes place based on client request category and dynamically estimating server workload using multi parameters like queue size, processing speed , bandwidth utilization etc on distributed multi clustered servers. Our simulation results shows that, the proposed method dynamically andefficiently balance the load to scale up the services , reducing response time, throughput on clustered servers.

  3. Applying graph partitioning methods in measurement-based dynamic load balancing

    Energy Technology Data Exchange (ETDEWEB)

    Bhatele, Abhinav [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fourestier, Sebastien [Univ. of Bordeaux (France). Bordeaux Lab. for Research in Computer Science; Menon, Harshitha [Univ. of Illinois, Urbana-Champaign, IL (United States); Kale, Laxmikant V. [Univ. of Illinois, Urbana-Champaign, IL (United States); Pellegrini, Francois [Univ. of Bordeaux (France). Bordeaux Lab. for Research in Computer Science

    2011-09-26

    Load imbalance leads to an increasing waste of resources as an application is scaled to more and more processors. Achieving the best parallel efficiency for a program requires optimal load balancing which is a NP-hard problem. However, finding near-optimal solutions to this problem for complex computational science and engineering applications is becoming increasingly important. Charm++, a migratable objects based programming model, provides a measurement-based dynamic load balancing framework. This framework instruments and then migrates over-decomposed objects to balance computational load and communication at runtime. This paper explores the use of graph partitioning algorithms, traditionally used for partitioning physical domains/meshes, for measurement-based dynamic load balancing of parallel applications. In particular, we present repartitioning methods developed in a graph partitioning toolbox called SCOTCH that consider the previous mapping to minimize migration costs. We also discuss a new imbalance reduction algorithm for graphs with irregular load distributions. We compare several load balancing algorithms using microbenchmarks on Intrepid and Ranger and evaluate the effect of communication, number of cores and number of objects on the benefit achieved from load balancing. New algorithms developed in SCOTCH lead to better performance compared to the METIS partitioners for several cases, both in terms of the application execution time and fewer number of objects migrated.

  4. CLUSTER OF WORKSTATIONS BASED ON DYNAMIC LOAD BALANCING FOR PARALLEL TREE COMPUTATION DEPTH-FIRST-SEARCH

    Institute of Scientific and Technical Information of China (English)

    加力; 陆鑫达; 张健

    2002-01-01

    The real problem in cluster of workstations is the changes in workstation power or number of workstations or dynmaic changes in the run-time behavior of the application hamper the efficient use of resources. Dynamic load balancing is a technique for the parallel implementation of problems, which generate unpredictable workloads by migration work units from heavily loaded processor to lightly loaded processors at run-time. This paper proposed an efficient load balancing method in which parallel tree computations depth-first-search (DFS) generates unpredictable, highly imbalance workloads and moves through different phases detectable at run-time, where dynamic load balancing strategy is applicable in each phase running under the MPI(message passing interface) and Unix operating system on cluster of workstations parallel platform computing.

  5. Two Stage Secure Dynamic Load Balancing Architecture for SIP Server Clusters

    Directory of Open Access Journals (Sweden)

    G. Vennila

    2014-08-01

    Full Text Available Session Initiation Protocol (SIP is a signaling protocol emerged with an aim to enhance the IP network capabilities in terms of complex service provision. SIP server scalability with load balancing has a greater concern due to the dramatic increase in SIP service demand. Load balancing of session method (request/response and security measures optimizes the SIP server to regulate of network traffic in Voice over Internet Protocol (VoIP. Establishing a honeywall prior to the load balancer significantly reduces SIP traffic and drops inbound malicious load. In this paper, we propose Active Least Call in SIP Server (ALC_Server algorithm fulfills objectives like congestion avoidance, improved response times, throughput, resource utilization, reducing server faults, scalability and protection of SIP call from DoS attacks. From the test bed, the proposed two-tier architecture demonstrates that the ALC_Server method dynamically controls the overload and provides robust security, uniform load distribution for SIP servers.

  6. Improving Performance of Dynamic Load Balancing among Web Servers by Using Number of Effective Parameters

    Directory of Open Access Journals (Sweden)

    Deepti Sharma

    2016-12-01

    Full Text Available Web application is being challenged to develop methods and techniques for large data processing at optimum response time. There are technical challenges in dealing with the increasing demand to handle vast traffic on these websites. As number of users‟ increases, several problems are faced by web servers like bottleneck, delayed response time, load balancing and density of services. The whole traffic cannot reside on a single server and thus there is a fundamental requirement of allocating this huge traffic on multiple load balanced servers. Distributing requests among servers in the web server clusters is the most important means to address such challenge, especially under intense workloads. In this paper, we propose a new request distribution algorithm for load balancing among web server clusters. The Dynamic Load Balancing among web servers take place based on user‟s request and dynamically estimating server workload using multiple parameters like processing and memory requirement, expected execution time and various time intervals. Our simulation results show that, the proposed method dynamically and efficiently balance the load to scale up the services, calculate average response time, average waiting time and server‟s throughput on different web servers. At the end of the paper, we presented an experimentation of running proposed system which proves the proposed algorithm is effic ient in terms of speed of processing, response time, server utilization and cost efficiency

  7. Dynamic Load Balancing Based on Restricted Multicast Tree in Homogeneous Multiprocessor Systems

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; SHI Feng; GAO Yu-jin

    2008-01-01

    To decrease the cost of exchanging load information among processors, a dynamic load-balancing (DLB) algorithm which adopts multicast tree technology is proposed. The multicast tree construction rules are also proposed to avoid wrongly transferred or redundant DLB messages due to the overlapping of multicast trees. The proposed DLB algorithm is distributed controlled, sender initiated and can help heavily loaded processors with complete distribution of redundant loads with minimum number of executions. Experiments were executed to compare the effects of the proposed DLB algorithm and other three ones, the results prove the effectivity and practicability of the proposed algorithm in dealing with great scale compute-intensive tasks.

  8. Efficient graph-based dynamic load-balancing for parallel large-scale agent-based traffic simulation

    NARCIS (Netherlands)

    Xu, Y.; Cai, W.; Aydt, H.; Lees, M.; Tolk, A.; Diallo, S.Y.; Ryzhov, I.O.; Yilmaz, L.; Buckley, S.; Miller, J.A.

    2014-01-01

    One of the issues of parallelizing large-scale agent-based traffic simulations is partitioning and load-balancing. Traffic simulations are dynamic applications where the distribution of workload in the spatial domain constantly changes. Dynamic load-balancing at run-time has shown better efficiency

  9. AN ADVANCED DYNAMIC FEEDBACK AND RANDOM DISPATCHING LOAD-BALANCING ALGORITHM FOR GMLC IN 3G

    Institute of Scientific and Technical Information of China (English)

    Liao Jianxin; Zhang Hao; Zhu Xiaomin

    2006-01-01

    Based on the system architecture and software structure of GMLC (Gateway Mobile Location Center) in 3G (third generation), a new dynamic load-balancing algorithm is proposed. It bases on dynamic feedback and imports the increment for admitting new request into the load forecast. It dynamically adjusts the dispatching probability according to the remainder process capability of each node. Experiments on the performance of algorithm have been carried out in GMLC and the algorithm is compared with Pick-KX algorithm and DFB (Dynamic FeedBack) algorithm in average throughput and average response time. Experiments results show that the average throughput of the proposed algorithm is about five percents higher than that of the other two algorithms and the average response time is four percents higher under high system loading condition.

  10. Portable Parallel Programming for the Dynamic Load Balancing of Unstructured Grid Applications

    Science.gov (United States)

    Biswas, Rupak; Das, Sajal K.; Harvey, Daniel; Oliker, Leonid

    1999-01-01

    The ability to dynamically adapt an unstructured -rid (or mesh) is a powerful tool for solving computational problems with evolving physical features; however, an efficient parallel implementation is rather difficult, particularly from the view point of portability on various multiprocessor platforms We address this problem by developing PLUM, tin automatic anti architecture-independent framework for adaptive numerical computations in a message-passing environment. Portability is demonstrated by comparing performance on an SP2, an Origin2000, and a T3E, without any code modifications. We also present a general-purpose load balancer that utilizes symmetric broadcast networks (SBN) as the underlying communication pattern, with a goal to providing a global view of system loads across processors. Experiments on, an SP2 and an Origin2000 demonstrate the portability of our approach which achieves superb load balance at the cost of minimal extra overhead.

  11. On—Line Predicting Behaviors of Jobs in Dynamic Load Balancing

    Institute of Scientific and Technical Information of China (English)

    鞠九滨; 徐高潮; 等

    1996-01-01

    A key issue of dynamic load balancing in a lossely coupled distributed system is selecting appropriate jobs to transfer.In this paper,a job selection policy based on on-line predicting behaviors of jobs is proposed.Tracing is used at the beginning of execution of a job to predict the approximate execution time and resource requirements of th job so as to make a correct decision about whether transferring the job is worthwhil.A dynamic load balancer using the job selection policy has been implemented.Experimental measurement results show that the policy proposed is able to improve mean response time of jobs and resource utilization of systems substantially.

  12. Parallel Cellular Automata-based simulation of laser dynamics using dynamic load balancing

    NARCIS (Netherlands)

    Guisado, J.L.; Fernández de Vega, F.; Jiménez Morales, F.; Iskra, K.A.; Sloot, P.M.A.; Garnica, Ó.

    2008-01-01

    In order to analyze the feasibility of executing a parallel bioinspired model of laser dynamics on a heterogeneous non-dedicated cluster, we evaluate its performance including artificial load to simulate other tasks or jobs submitted by other users. As the model is based on a synchronous cellular

  13. Parallel Cellular Automata-based simulation of laser dynamics using dynamic load balancing

    NARCIS (Netherlands)

    Guisado, J.L.; Fernández de Vega, F.; Jiménez Morales, F.; Iskra, K.A.; Sloot, P.M.A.; Garnica, Ó.

    2008-01-01

    In order to analyze the feasibility of executing a parallel bioinspired model of laser dynamics on a heterogeneous non-dedicated cluster, we evaluate its performance including artificial load to simulate other tasks or jobs submitted by other users. As the model is based on a synchronous cellular au

  14. Implementation Study of Dynamic Load Balancing Algorithm of Parallel Tree Computation on Clusters of Heterogeneous Workstation

    Institute of Scientific and Technical Information of China (English)

    Mohammed A.M. Ibrahim; Lu Xinda; M. SaifMokbel

    2005-01-01

    The rapid growth of interconnected high performance workstations has produced a new computing paradigm called clustered of workstations computing. In these systems load balance problem is a serious impediment to achieve good performance. The main concern of this paper is the implementation of dynamic load balancing algorithm,asynchronous Round Robin (ARR), for balancing workload of parallel tree computation depth-first-search algorithm on Cluster of Heterogeneous Workstations (COW) Many algorithms in artificial intelligence and other areas of computer science are based on depth first search in implicitty defined trees. For these algorithms a loadbalancing scheme is required, which is able to evenly distribute parts of an irregularly shaped tree over the workstations with minimal interprocessor communication and without prior knowledge of the tree's shape. For the( ARR ) algorithm only minimal interpreeessor communication is needed when necessary and it runs under the MPI (Message passing interface) that allows parallel execution on heterogeneous SUN cluster of workstation platform. The program code is written in C language and executed under UNIX operating system (Solaris version).

  15. Dynamic Allocation Method For Efficient Load Balancing In Virtual Machines For Cloud Computing Environment

    Directory of Open Access Journals (Sweden)

    Bhaskar. R

    2012-10-01

    Full Text Available This paper proposes a Dynamic resource allocation method for Cloud computing. Cloud computing is amodel for delivering information technology services in which resources are retrieved from the internetthrough web-based tools and applications, rather than a direct connection to a server. Users can set upand boot the required resources and they have to pay only for the required resources. Thus, in thefuture providing a mechanism for efficient resource management and assignment will be an importantobjective of Cloud computing. In this project we propose a method, dynamic scheduling andconsolidation mechanism that allocate resources based on the load of Virtual Machines (VMs onInfrastructure as a service (IaaS. This method enables users to dynamically add and/or delete one ormore instances on the basis of the load and the conditions specified by the user.Our objective is to develop an effective load balancing algorithm using Virtual Machine Monitoring tomaximize or minimize different performance parameters(throughput for example for the Clouds ofdifferent sizes (virtual topology de-pending on the application requirement.

  16. Dynamic task scheduling algorithm with load balancing for heterogeneous computing system

    Directory of Open Access Journals (Sweden)

    Doaa M. Abdelkader

    2012-07-01

    Full Text Available In parallel computation, the scheduling and mapping tasks is considered the most critical problem which needs High Performance Computing (HPC to solve it by breaking the problem into subtasks and working on those subtasks at the same time. The application sub tasks are assigned to underline machines and ordered for execution according to its proceeding to grantee efficient use of available resources such as minimize execution time and satisfy load balance between processors of the underline machine. The underline infrastructure may be homogeneous or heterogeneous. Homogeneous infrastructure could use the same machines power and performance. While heterogeneous infrastructure include machines differ in its performance, speed, and interconnection. According to work in this paper a new dynamic task scheduling algorithm for Heterogeneous called a Clustering Based HEFT with Duplication (CBHD have been developed. The CBHD algorithm is considered an amalgamation between the most two important task scheduling in Heterogeneous machine, The Heterogeneous Earliest Finish Time (HEFT and the Triplet Clustering algorithms. In the CBHD algorithm the duplication is required to improve the performance of algorithm. A comparative study among the developed CBHD, the HEFT, and the Triplet Cluster algorithms has been done. According to the comparative results, it is found that the developed CBHD algorithm satisfies better execution time than both HEFT algorithm and Triplet Cluster algorithm, and in the same time, it achieves the load balancing which considered one of the main performance factors in the dynamic environment.

  17. Dynamic load balancing of matrix-vector multiplications on roadrunner compute nodes

    Energy Technology Data Exchange (ETDEWEB)

    Sancho Pitarch, Jose Carlos [Los Alamos National Laboratory

    2009-01-01

    Hybrid architectures that combine general purpose processors with accelerators are being adopted in several large-scale systems such as the petaflop Roadrunner supercomputer at Los Alamos. In this system, dual-core Opteron host processors are tightly coupled with PowerXCell 8i processors within each compute node. In this kind of hybrid architecture, an accelerated mode of operation is typically used to offload performance hotspots in the computation to the accelerators. In this paper we explore the suitability of a variant of this acceleration mode in which the performance hotspots are actually shared between the host and the accelerators. To achieve this we have designed a new load balancing algorithm, which is optimized for the Roadrunner compute nodes, to dynamically distribute computation and associated data between the host and the accelerators at runtime. Results are presented using this approach for sparse and dense matrix-vector multiplications that show load-balancing can improve performance by up to 24% over solely using the accelerators.

  18. A Novel Dynamic Adjusting Algorithm for Load Balancing and Handover Co-Optimization in LTE SON

    Institute of Scientific and Technical Information of China (English)

    Wen-Yu Li; Xiang Zhang; Shu-Cong Jia; Xin-Yu Gu; Lin Zhang; Xiao-Yu Duan; Jia-Ru Lin

    2013-01-01

    With the development of mobile internet and multi-media service,advanced techniques need to be applied in wireless network to improve user experience.Long term evolution (LTE) systems,which can offer up to 100Mbps downlink date rates,have been deployed in USA and Korea.However,because plenty of complex physical layer algorithms are utilized,network planning and optimization become heavy burdens for LTE network operators.Self-organizing network (SON) is a promising method to overcome this problem by automatically selecting and adjusting key parameters in LTE systems.In this paper,we present a dynamic adjusting algorithm to improve both handover and load balancing performance by introducing a weighted co-satisfaction factor (CSF).Analysis and system level simulation are conducted to exhibit the performance improvement of the proposed scheme.Results show that the proposed method outperforms the conventional solutions in terms of the network handover success ratio and load balancing gains significantly.

  19. Mizan: A system for dynamic load balancing in large-scale graph processing

    KAUST Repository

    Khayyat, Zuhair

    2013-01-01

    Pregel [23] was recently introduced as a scalable graph mining system that can provide significant performance improvements over traditional MapReduce implementations. Existing implementations focus primarily on graph partitioning as a preprocessing step to balance computation across compute nodes. In this paper, we examine the runtime characteristics of a Pregel system. We show that graph partitioning alone is insufficient for minimizing end-to-end computation. Especially where data is very large or the runtime behavior of the algorithm is unknown, an adaptive approach is needed. To this end, we introduce Mizan, a Pregel system that achieves efficient load balancing to better adapt to changes in computing needs. Unlike known implementations of Pregel, Mizan does not assume any a priori knowledge of the structure of the graph or behavior of the algorithm. Instead, it monitors the runtime characteristics of the system. Mizan then performs efficient fine-grained vertex migration to balance computation and communication. We have fully implemented Mizan; using extensive evaluation we show that - especially for highly-dynamic workloads - Mizan provides up to 84% improvement over techniques leveraging static graph pre-partitioning. © 2013 ACM.

  20. Energy Efficient Cooperative Spectrum Sensing in Cognitive Radio Networks Using Distributed Dynamic Load Balanced Clustering Scheme

    Directory of Open Access Journals (Sweden)

    Muthukkumar R.

    2016-07-01

    Full Text Available Cognitive Radio (CR is a promising and potential technique to enable secondary users (SUs or unlicenced users to exploit the unused spectrum resources effectively possessed by primary users (PUs or licenced users. The proven clustering approach is used to organize nodes in the network into the logical groups to attain energy efficiency, network scalability, and stability for improving the sensing accuracy in CR through cooperative spectrum sensing (CSS. In this paper, a distributed dynamic load balanced clustering (DDLBC algorithm is proposed. In this algorithm, each member in the cluster is to calculate the cooperative gain, residual energy, distance, and sensing cost from the neighboring clusters to perform the optimal decision. Each member in a cluster participates in selecting a cluster head (CH through cooperative gain, and residual energy that minimises network energy consumption and enhances the channel sensing. First, we form the number of clusters using the Markov decision process (MDP model to reduce the energy consumption in a network. In this algorithm, CR users effectively utilize the PUs reporting time slots of unavailability. The simulation results reveal that the clusters convergence, energy efficiency, and accuracy of channel sensing increased considerably by using the proposed algorithm.

  1. Adaptive and Dynamic Load Balancing Methodologies For Distributed Environment: A Review

    Directory of Open Access Journals (Sweden)

    Sandip Kumar Goyal,

    2011-03-01

    Full Text Available Distributed network computing environments have become a cost effective and popular choice to achieve high performance and to solve large scale computation problems. Unlike past supercomputers, a cluster or grid or peer-to-peer (P2P system can be used as multipurpose computing platform to run diverse high performance parallel applications. Cluster computing environment consist of Personal Computers (PCs that are interconnected using high speed networks and are located at same location where as grid computing involves coupled and coordinated use of geographically distributed resources for purposes such as large scale computation and distributed data analysis. Peer-To-Peer is composed of participantsthat make a portion of their resources (such as processing power, disk storage, and network bandwidth available directly to their peers without intermediary network hosts or servers. Load Balancing (LB in a Distributed System is a process of sharing computational resources by transparently distributing system workload. A istributed computing system consists of software programs and data resources dispersed across independent devices. A workstation user may not use the machine all the time, but may require more than it can provide while actively working. Some devices may be heavily loaded, while other remains idle. Performance enhancement is one of the most important issues in DS. The performance of the system can often be improved to an acceptable level simply by distributing the load among the devices.

  2. A study on the Dynamic Load Balancing Model based on Main Load Information Table and the Load Balancing Algorithm%一种基于主负载信息表的动态负载平衡模型及其均衡算法研究

    Institute of Scientific and Technical Information of China (English)

    华强胜; 陈志刚; 李登

    2002-01-01

    The study on the static and dynamic load balancing algorithms has a history over three decades and it is stilla promising field. But because of the uncertainties between the dependencies of the parallel tasks and their communi-cation during the compile-time, researchers are more inclined to study the dynamic load balancing algorithms(DLB).There are almost four kinds of DLB algorithms including the centralized DLB, distributed DLB, global DLB and LocalDLB, all of them have their pros and cons. This paper addresses a new dynamic load balancing model based on theMain Load Information Table (MLIT) and its dynamic load balancing algorithm, it not only has the advantages thefour models above mentioned have, but it overcomes some of their disadvantages which lead to a poor performance,thus it boasts a better stability and security and in the end it can improve the performance of the system.

  3. Internet Load and Traffic Balancing

    Institute of Scientific and Technical Information of China (English)

    李文正; 郭巧; 郭为民

    2005-01-01

    Load and traffic balancing for the Internet are analyzed. An intelligent domain name system(DNS) policy for the control and management of content distribution networks (CDN) is presented. An CDNs network based Urtitech IntelliDNS is built, and performance of the network in realizing traffic and load balancing is measured. It is proved that CDNs provide a valuable service and the methods are feasible.

  4. Quasirandom Load Balancing

    CERN Document Server

    Friedrich, Tobias; Sauerwald, Thomas

    2010-01-01

    We propose a simple distributed algorithm for balancing indivisible tokens on graphs. The algorithm is completely deterministic, though it tries to imitate (and enhance) a random algorithm by keeping the accumulated rounding errors as small as possible. Our new algorithm surprisingly closely approximates the idealized process (where the tokens are divisible) on important network topologies. On d-dimensional torus graphs with n nodes it deviates from the idealized process only by an additive constant. In contrast to that, the randomized rounding approach of Friedrich and Sauerwald (2009) can deviate up to Omega(polylog(n)) and the deterministic algorithm of Rabani, Sinclair and Wanka (1998) has a deviation of Omega(n^{1/d}). This makes our quasirandom algorithm the first known algorithm for this setting which is optimal both in time and achieved smoothness. We further show that also on the hypercube our algorithm has a smaller deviation from the idealized process than the previous algorithms.

  5. Queuing delays in randomized load balanced networks

    NARCIS (Netherlands)

    Borst, S.C.; et al, not CWI

    2007-01-01

    Valiant’s concept of Randomized Load Balancing (RLB), also promoted under the name ‘two-phase routing’, has previously been shown to provide a cost-effective way of implementing overlay networks that are robust to dynamically changing demand patterns. RLB is accomplished in two steps; in the first s

  6. Equilibria in Load Balancing Games

    Institute of Scientific and Technical Information of China (English)

    Bo Chen

    2009-01-01

    A Nash equilibrium (NE) in a multi-agent game is a strategy profile that is resilient to unilateral deviations.A strong Nash equilibrium (SE) is one that is stable against coordinated deviations of any coalition.We show that,in the load balancing games,NEs approximate SEs in the sense that the benefit of each member of any coalition from coordinated deviations is well limited.Furthermore,we show that an easily recognizable special subset of NEs exhibit even better approximation of SEs.

  7. A New Load Balancing Scheme on Heterogeneous Database Cluster

    Institute of Scientific and Technical Information of China (English)

    GONG Weihua; WANG Yuanzhen

    2006-01-01

    In heterogeneous database cluster, the performance of load balancing is closely related to the computing capabilities of heterogeneous nodes and the different types of workloads. Thus, a method is introduced to evaluate the load status of nodes by the weighted load values with consideration of both the utilization of different resources and the workload types in a load balancer and an efficient and dynamic load balancing scheme is proposed for OLTP(online transaction processing) workloads to maximize the utilization of distributed resources and achieve better performance, which need not collect the feedback of load information from the lower nodes and effectively keeps from the data skew. The simulation results for OLTP services gained by TPC-C tool show that the dynamic weighted balancing policy leads to sub-linear throughput speedup and keeps the heterogeneous cluster well balanced.

  8. Large-scale Particle Simulations for Debris Flows using Dynamic Load Balance on a GPU-rich Supercomputer

    Science.gov (United States)

    Tsuzuki, Satori; Aoki, Takayuki

    2016-04-01

    Numerical simulations for debris flows including a countless of objects is one of important topics in fluid dynamics and many engineering applications. Particle-based method is a promising approach to carry out the simulations for flows interacting with objects. In this paper, we propose an efficient method to realize a large-scale simulation for fluid-structure interaction by combining SPH (Smoothed Particle Hydrodynamics) method for fluid with DEM (Discrete Element Method) for objects on a multi-GPU system. By applying space filling curves to decomposition of the computational domain, we are able to contain the same number of particles in each decomposed domain. In our implementation, several techniques for particle counting and data movement have been introduced. Fragmentation of the memory used for particles happens during the time-integration and the frequency of de-fragmentation is examined by taking account for computational load balance and the communication cost between CPU and GPU. A link-list technique of the particle interaction is introduced to save the memory drastically. It is found that the sorting of particle data for the neighboring particle list using linked-list method improves the memory access greatly with a certain interval. The weak and strong scalabilities for a SPH simulation using 111 Million particles was measured from 4 GPUs to 512 GPUs for three types of space filling curves. A large-scale debris flow simulation of tsunami with 10,368 floating rubbles using 117 Million particles were successfully carried out with 256 GPUs on the TSUBAME 2.5 supercomputer at Tokyo Institute of Technology.

  9. An Improved Hadoop Data Load Balancing Algorithm

    Directory of Open Access Journals (Sweden)

    Kun Liu

    2013-12-01

    Full Text Available Data load balancing is one of the key problems of big data technology. As a big data application, Hadoop has had many successful applications. HDFS is Hadoop Distributed File System and has the load balancing procedure which can balance the storage load on each machine. However, this method cannot balance the overload rack preferentially, and so it is likely to cause the breakdown of overload machines. In this paper, we focus on the overload machines and propose an improved algorithm for balancing the overload racks preferentially. The improved method constructs Prior Balance List list which includes overload machines, For Balance List list and NextForBalanceList list by many factors and balances among the racks selected from these lists firstly. Experiments show that the improved method can balance the overload racks in time and reduce the possibility of breakdown of these racks

  10. Consideration of Dynamical Balances

    Science.gov (United States)

    Errico, Ronald M.

    2015-01-01

    The quasi-balance of extra-tropical tropospheric dynamics is a fundamental aspect of nature. If an atmospheric analysis does not reflect such balance sufficiently well, the subsequent forecast will exhibit unrealistic behavior associated with spurious fast-propagating gravity waves. Even if these eventually damp, they can create poor background fields for a subsequent analysis or interact with moist physics to create spurious precipitation. The nature of this problem will be described along with the reasons for atmospheric balance and techniques for mitigating imbalances. Attention will be focused on fundamental issues rather than on recipes for various techniques.

  11. Load balancing in integrated optical wireless networks

    DEFF Research Database (Denmark)

    Yan, Ying; Dittmann, Lars; Wong, S-W.;

    2010-01-01

    In this paper, we tackle the load balancing problem in Integrated Optical Wireless Networks, where cell breathing technique is used to solve congestion by changing the coverage area of a fully loaded cell tower. Our objective is to design a load balancing mechanism which works closely with the in......In this paper, we tackle the load balancing problem in Integrated Optical Wireless Networks, where cell breathing technique is used to solve congestion by changing the coverage area of a fully loaded cell tower. Our objective is to design a load balancing mechanism which works closely...... issues are outlined and a cost function based optimization model is developed for power management. In particularly, two alternative feedback schemes are proposed to report wireless network status. Simulation results show that our proposed load balancing mechanism improves network performances....

  12. GENETIC ALGORITHM BASED CONCEPT DESIGN TO OPTIMIZE NETWORK LOAD BALANCE

    Directory of Open Access Journals (Sweden)

    Ashish Jain

    2012-07-01

    Full Text Available Multiconstraints optimal network load balancing is an NP-hard problem and it is an important part of traffic engineering. In this research we balance the network load using classical method (brute force approach and dynamic programming is used but result shows the limitation of this method but at a certain level we recognized that the optimization of balanced network load with increased number of nodes and demands is intractable using the classical method because the solution set increases exponentially. In such case the optimization techniques like evolutionary techniques can employ for optimizing network load balance. In this paper we analyzed proposed classical algorithm and evolutionary based genetic approach is devise as well as proposed in this paper for optimizing the balance network load.

  13. Load balancing in distributed framework for frequency based thread pools

    Directory of Open Access Journals (Sweden)

    Sheraz Ahmad

    2016-12-01

    Full Text Available The consequence of load balancing algorithms on a thread pool framework name is distributed load balancing frequency based optimization scheme (LDFBOS to increase its execution. Load balancing in distributed frequency based thread pool scheme is residential towards the ground of synchronizing overhead crude named LDFBOS in Java that slows down its execution due to framework exchange and synchronizing overhead in nodes, we are demonstrating the contrive and execution of load balancing in distributed frequency based thread pool LDFBOS to does usage from distributed in frequency based thread pool (DFBOS, synchronizing primitives that propose benefits of significant scalable moreover, dynamism. We have got resembled the execution of some schemes by Thread Pool Tester which is a Java application simulator and the consequence have demonstrated that load balancing in distributed frequency based thread pool LDFBOS exceeds preceding DFBOS scheme.

  14. Load Balancing Algorithm for Cache Cluster

    Institute of Scientific and Technical Information of China (English)

    刘美华; 古志民; 曹元大

    2003-01-01

    By the load definition of cluster, the request is regarded as granularity to compute load and implement the load balancing in cache cluster. First, the processing power of cache-node is studied from four aspects: network bandwidth, memory capacity, disk access rate and CPU usage. Then, the weighted load of cache-node is customized. Based on this, a load-balancing algorithm that can be applied to the cache cluster is proposed. Finally, Polygraph is used as a benchmarking tool to test the cache cluster possessing the load-balancing algorithm and the cache cluster with cache array routing protocol respectively. The results show the load-balancing algorithm can improve the performance of the cache cluster.

  15. 一种支持邻居负载感知的动态负载平衡扩散算法%Dynamic Load Balancing Diffusion Algorithm with Neighbors Loading Awareness

    Institute of Scientific and Technical Information of China (English)

    余鑫; 张斌

    2013-01-01

    Dynamic load balancing is the primary means to adjust load distribution of network nodes. Compared with other load balancing algorithm, diffusion algorithm has advantage of performing synchronously, low migrating cost without center bottleneck, and so on. The paper proposed a dynamic loading balancing diffusion algorithm with neighbors loading awareness(NLA-LB) to improve FOS diffusion algorithm. To realize convergence acceleration, sender initiated policy was adopted to establish a dynamic migrating group,and then information of neighbor loading was used to calculate loading exchanging impact factor. Experiment result shows that NLA-BA's convergence speed can be improved efficiently with lesser migrating cost.%动态负载平衡是网络节点之间负载分布调整的主要手段.负载平衡中的扩散算法与其他算法相比具有各节点同步执行,迁移开销较小、不存在中心节点瓶颈等优势.对FOS (First Order Scheme)扩散算法进行改进,提出了支持邻居负载感知的动态负载平衡扩散算法(NLA-LB).采用了发送者启动的策略来建立迁移组,利用节点的邻居负载信息计算负载交换的影响因子,以实现对FOS算法的加速改进.实验证明,该算法有效提升了收敛速度.

  16. Load balancing by redundant decomposition and maping

    NARCIS (Netherlands)

    de Ronde, J.F.; Schoneveld, A.; Sloot, P.M.A.

    1997-01-01

    In this paper a new methodology for load balancing parallel processes on parallel systems is proposed. The problem of load balancing is considered to be an NP-hard optimization task. Taking static parallel finite element applications as a case study, the benefits and losses that follow from applying

  17. Load balancing by redundant decomposition and maping

    NARCIS (Netherlands)

    de Ronde, J.F.; Schoneveld, A.; Sloot, P.M.A.

    1997-01-01

    In this paper a new methodology for load balancing parallel processes on parallel systems is proposed. The problem of load balancing is considered to be an NP-hard optimization task. Taking static parallel finite element applications as a case study, the benefits and losses that follow from applying

  18. LOW-COST HIGH PERFORMANCE CLUSTER OF WORK- STATIONS BASED ON DYNAMIC LOAD BALANCING FOR PARALLEL DEPTH-FIRST SEARCH(DFS)

    Institute of Scientific and Technical Information of China (English)

    加力; 陆鑫达

    2002-01-01

    This paper presented an idea to replace the traditionally expensive parallel machines by heterogeneous cluster of workstations. To emphasise the usability of cluster of workstations platform for parallel and distributed computing, also the paper presented the status report on the effort and experiences for the implementation of a dynamic load balancing for parallel tree computation depth-first-search (DFS) on the cluster of a workstations project. It compared the speedup performance obtained from our platform with that obtained from the traditional one.The speedup results show that cluster of workstations can be a serious alternative to the expensive parallel machines.

  19. A LOAD BALANCING MODEL USING FIREFLY ALGORITHM IN CLOUD COMPUTING

    Directory of Open Access Journals (Sweden)

    A. Paulin Florence

    2014-01-01

    Full Text Available Cloud computing is a model that points at streamlining the on-demand provisioning of software, hardware and data as services and providing end-users with flexible and scalable services accessible through the Internet. The main objective of the proposed approach is to maximize the resource utilization and provide a good balanced load among all the resources in cloud servers. Initially, a load model of every resource will be derived based on several factors such as, memory usage, processing time and access rate. Based on the newly derived load index, the current load will be computed for all the resources shared in virtual machine of cloud servers. Once the load index is computed for all the resources, load balancing operation will be initiated to effectively use the resources dynamically with the process of assigning resources to the corresponding node to reduce the load value. So, assigning of resources to proper nodes is an optimal distribution problem so that many optimization algorithms such as genetic algorithm and modified genetic algorithm are utilized for load balancing. These algorithms are not much effective in providing the neighbour solutions since it does not overcome exploration and exploration problem. So, utilizing the effective optimization procedure instead of genetic algorithm can lead to better load balancing since it is a traditional and old algorithm. Accordingly, I have planned to utilize a recent optimization algorithm, called firefly algorithm to do the load balancing operation in our proposed work. At first, the index table will be maintained by considering the availability of virtual servers and sequence of request. Then, load index will be computed based on the newly derived formulae. Based on load index, load balancing operation will be carried out using firefly algorithm. The performance analysis produced expected results and thus proved the proposed approach is efficient in optimizing schedules by balancing the

  20. User Demand Aware Grid Scheduling Model with Hierarchical Load Balancing

    Directory of Open Access Journals (Sweden)

    P. Suresh

    2013-01-01

    Full Text Available Grid computing is a collection of computational and data resources, providing the means to support both computational intensive applications and data intensive applications. In order to improve the overall performance and efficient utilization of the resources, an efficient load balanced scheduling algorithm has to be implemented. The scheduling approach also needs to consider user demand to improve user satisfaction. This paper proposes a dynamic hierarchical load balancing approach which considers load of each resource and performs load balancing. It minimizes the response time of the jobs and improves the utilization of the resources in grid environment. By considering the user demand of the jobs, the scheduling algorithm also improves the user satisfaction. The experimental results show the improvement of the proposed load balancing method.

  1. Load-balancing algorithms for climate models

    Energy Technology Data Exchange (ETDEWEB)

    Foster, I.T.; Toonen, B.R.

    1994-06-01

    Implementations of climate models on scalable parallel computer systems can suffer from load imbalances due to temporal and spatial variations in the amount of computation required for physical parameterizations such as solar radiation and convective adjustment. We have developed specialized techniques for correcting such imbalances. These techniques are incorporated in a general-purpose, programmable load-balancing library that allows the mapping of computation to processors to be specified as a series of maps generated by a programmer-supplied load-balancing module. The communication required to move from one map to another is performed automatically by the library, without programmer intervention. In this paper, we de scribe the load-balancing problem and the techniques that we have developed to solve it. We also describe specific load-balancing algorithms that we have developed for PCCM2, a scalable parallel implementation of the community Climate Model, and present experimental results that demonstrate the effectiveness of these algorithms on parallel computers.

  2. Load-balancing algorithms for climate models

    Science.gov (United States)

    Foster, I. T.; Toonen, B. R.

    Implementations of climate models on scalable parallel computer systems can suffer from load imbalances due to temporal and spatial variations in the amount of computation required for physical parameterizations such as solar radiation and convective adjustment. We have developed specialized techniques for correcting such imbalances. These techniques are incorporated in a general-purpose, programmable load-balancing library that allows the mapping of computation to processors to be specified as a series of maps generated by a programmer-supplied load-balancing module. The communication required to move from one map to another is performed automatically by the library, without programmer intervention. In this paper, we describe the load-balancing problem and the techniques that we have developed to solve it. We also describe specific load-balancing algorithms that we have developed for PCCM2, a scalable parallel implementation of the community climate model, and present experimental results that demonstrate the effectiveness of these algorithms on parallel computers.

  3. Cell Load Balancing in Heterogeneous Scenarios

    DEFF Research Database (Denmark)

    Eduardo, Simao; Rodrigues, Antonio; Mihovska, Albena D.

    2013-01-01

    Cell load imbalances in wireless networks degrade performance. Macro and small cell collocated deployments (heterogeneous scenario) constitutes a new problem for load balancing. This paper proposes a novel admission control algorithm for an optimal solution to the assignment of traffic flows...

  4. Improving load balance with flexibly assignable tasks

    Energy Technology Data Exchange (ETDEWEB)

    Pinar, Ali; Hendrickson, Bruce

    2003-09-09

    In many applications of parallel computing, distribution ofthe data unambiguously implies distribution of work among processors. Butthere are exceptions where some tasks can be assigned to one of severalprocessors without altering the total volume of communication. In thispaper, we study the problem of exploiting this flexibility in assignmentof tasks to improve load balance. We first model the problem in terms ofnetwork flow and use combinatorial techniques for its solution. Ourparametric search algorithms use maximum flow algorithms for probing on acandidate optimal solution value. We describe two algorithms to solve theassignment problem with \\logW_T and vbar P vbar probe calls, w here W_Tand vbar P vbar, respectively, denote the total workload and number ofproce ssors. We also define augmenting paths and cuts for this problem,and show that anyalgorithm based on augmenting paths can be used to findan optimal solution for the task assignment problem. We then consideracontinuous version of the problem, and formulate it as a linearlyconstrained optimization problem, i.e., \\min\\|Ax\\|_\\infty,\\; {\\rms.t.}\\;Bx=d. To avoid solving an intractable \\infty-norm optimization problem,we show that in this case minimizing the 2-norm is sufficient to minimizethe \\infty-norm, which reduces the problem to the well-studiedlinearly-constrained least squares problem. The continuous version of theproblem has the advantage of being easily amenable to parallelization.Our experiments with molecular dynamics and overlapped domaindecomposition applications proved the effectiveness of our methods withsignificant improvements in load balance. We also discuss how ourtechniques can be enhanced for heterogeneous systems.

  5. LEACH Algorithm Based on Load Balancing

    Directory of Open Access Journals (Sweden)

    Wangang Wang

    2013-09-01

    Full Text Available This paper discusses advantages of LEACH Algorithm and the existing improved model which takes the famous hierarchy clustering routing protocol LEACH Algorithm as researching object. Then the paper indicates the problem that in the algorithm capacity factor of cluster head node is not taken into account leading the structure of clusters to be not so reasonable. This research discusses an energy-uniform cluster and cluster head selecting mechanism in which “Pseudo cluster head” concept is introduced in order to coordinate with “Load Monitor” Mechanism and “Load Leisure” Mechanism to maintain load balancing of cluster head character and stability of network topology. On the basis of LEACH Protocol improving algorithm of LEACH-C, CEFL and DCHS. NS2 simulation instrument is applied to do simulation analysis on the improved algorithm. Simulation result shows that LEACH-P Protocol effectively increase energy utilization efficiency, lengthens network lifetime and balances network load.  

  6. Hydraulic balance by means of electromotoric HKV drives for dynamic load profiles; Hydraulischer Abgleich mittels elektromotorischer HKV-Antriebe fuer dynamische Lastprofile

    Energy Technology Data Exchange (ETDEWEB)

    Szendrei, Danny [Westsaechsische Hochschule Zwickau (Germany)

    2010-07-01

    To date, measures and concepts for saving energy become more and more important. The development of prices for conventional energy sources forces public and private households and businesses to changes in consumer behaviour and purchasing behaviour. Due to the structural infrastructure, the housing construction in communes strongly is affected by these developments. Nearly 35 % of the total energy demand in Europe account for heating of buildings generally. The most common type of heating system for heating of residential buildings is the central hot water heating in the two-tube version. It is assumed that nearly 90 % of the operated plants have a hydraulic unbalance. Additionally, balanced heating systems fulfil the desired efficiency only under certain, structural design conditions. The integration of the control of heating systems in the smart home infrastructure or KNX infrastructure enables a building-independent, tunable heat supply between buildings and consumption acquisition. The hydraulic system loads can be optimized simultaneously via the direct access to the control value. Thus, a homogeneous mass distribution over the plant can be guaranteed which is derived from the dynamic needs of the system users. These heat loads are calculated by the KNX system and the application of HeatingControl.

  7. Balancer effects in opinion dynamics

    CERN Document Server

    Cheon, Taksu

    2016-01-01

    We introduce a novel type of contrarian agent, the balancer, to Galam model of opinion dynamics, in order to account for the skepticism over one-sidedness and for the sense of fairness. We find that the inclusion of balancers along with floaters and inflexibles brings about a critical point on parametric plane of the dynamical system, which results in the new kind of stable final states of the opinion dynamics, that seem to capture several intriguing features found often in mature democracies.

  8. Load Balancing on Open Networks: A Mobile Agent Approach

    Directory of Open Access Journals (Sweden)

    R. B. Patel

    2006-01-01

    Full Text Available In order to disperse the load on a Web server, generally the server cluster is configured to distribute access requests, or mirror servers are distributed geographically on different networks. Use of the Internet and the World-Wide-Web (WWW has become widespread in recent years and mobile agent technology has proliferated at an equally rapid rate to evenly distribute the requests to web servers through load balancing. There are various loads balancing policies came into picture. Primitive one is Message Passing Interface (MPI. Its wide availability and portability make it an attractive choice, however the communication requirements are sometimes inconventior and inefficient when implementing the primitives provided by MPI. Mobile agent (MA based approach have the merits of high flexibility, efficiency, low network traffic, less communication latency as well as highly asynchronous. In this study we present dynamic load balancing using mobile agent technology in which when a node is overloaded, task migrates to less utilized nodes so as to share the workload. However, the decision of which nodes receive migrating task is made in real-time by design and implementation of a framework called Platform for Load balancing (PLB. It is implemented on PMADE (A Platform for Mobile Agent Distribution and Execution. PLB integrated web servers can dispatch MAs to retrieve load information and accomplish load redistribution on all servers. The performance evaluation demonstrates that the PLB framework provides a foundation to develop efficient load balancing schemes on wide range of web server systems from cluster to open network and the results of a comparison of PLB, with some existing ones, is also reported.

  9. Software agents for distributed load balancing

    Energy Technology Data Exchange (ETDEWEB)

    Wernstedt, F.; Davidsson, P. [Department of Systems and Software Engineering, School of Engineering, Blekinge Institute of Technology, Ronneby (Sweden)

    2004-07-01

    We present results from experiments where the effects of flow control at a single substation are compared to distributed flow control at multiple substations. The latter approach is made possible by equipping individual substations with some computing power and integrating them into a communications network. Software agents, who cooperate with other software agents (substations) and invoke time limited reductions to consumption, are embedded in each substation. The experiments show that it is possible to automatically load balance a small district heating network using agent technology, e.g., to perform automatic peak clipping and load shifting. (orig.)

  10. Manet Load Balancing Parallel Routing Protocol

    Directory of Open Access Journals (Sweden)

    Hesham Arafat Ali

    2012-07-01

    Full Text Available In recent years, multi-path routing protocols have attained more attention in mobile ad hoc networks as compared to other routing schemes due to their abilities and efficiency in improving bandwidth of communication, increasing delivery reliability, responding to congestion and heavy traffic. Several protocols have been developed to address multi path routing, but it always has a problem that the discovered paths may be not 100% disjoint and sending data is done in only one path until it's broken; the discovery of multiple paths also generates more overhead on the network. Load Balancing Parallel Routing Protocol [LBPRP] tried to solve previous multi path problems, distributing traffic among multiple paths sending data in parallel form as it uses all paths in the same time. We employed a simple test scenario to be sure of proposed model efficiency and to validate the proposed Load Balancing Parallel Routing Protocol. [LBPRP] will achieve load balancing in sending data, decreasing the end-to-end delay and increasing the packet delivery ratio and throughput, thus the performance of multi-path routing protocols can be improved consequently.

  11. 杆式应变天平变负载动态建模和分段动态补偿%Dynamic modeling and staged compensation of bar-shaped strain gauge balance with changing load

    Institute of Scientific and Technical Information of China (English)

    周全; 徐科军; 杨双龙

    2012-01-01

    杆式应变天平安装在飞行器模型中,用于测量飞行器模型在风洞实验中所受的空气动力和力矩.模型相当于天平的负载.为了研究负载对天平动态特性的影响,通过改变天平上的配重砝码质量,进行不同负载下的天平动态标定实验.采用OE模型描述在不同负载下,天平各通道的数学模型.根据模型得到动态特征参数.通过曲线拟合,表示天平特征参数与负载质量之间的变化规律.为了保证在不同负载下,天平均具有较好的动态响应性能,提出依据负载变化的分段动态补偿的思路,实现对不同负载实验数据的动态补偿,取得较好效果.%In the wind tunnel experiment, bar-shaped strain gauge balance installed in aircraft model is used to measure the aerodynamic forces and moments applied to the aircraft model. The aircraft model can be regarded as the load of the balance. In order to research the effect of load on the dynamic characteristic of the balance, the dynamic calibration experiments are conducted with different loads that are realized by changing weights. The system identification method based on output error model is adopted to describe the dynamic mathematical models for various channels of the balance with different loads. Their dynamic characteristic parameters are obtained according to the models. The curve fitting method is used to present the varying pattern between the characteristic parameters of the balance and the mass of loads. A kind of staged dynamic compensation solution is proposed to ensure good dynamic response performance under different loads. It implements the dynamic compensation for experimental data of different loads, and achieves good results.

  12. Cell Load Balancing in Heterogeneous Scenarios

    DEFF Research Database (Denmark)

    Eduardo, Simao; Rodrigues, Antonio; Mihovska, Albena D.

    2013-01-01

    Cell load imbalances in wireless networks degrade performance. Macro and small cell collocated deployments (heterogeneous scenario) constitutes a new problem for load balancing. This paper proposes a novel admission control algorithm for an optimal solution to the assignment of traffic flows....... It jointly performs congestion control and inter-cell interference avoidance by means of a utility describing the cell's channel. Centralized and uncoordinated schemes are studied. The first is defined as an integer linear program, while the second builds on the best channel utility developed for the first...... and combines it with a stochastic admission process. Based on simulation evaluation, it is shown that uncoordinated is near-optimal, while providing a viable solution for uncoordinated small cell deployments. Finally, the best utility developed proved better than the traditional power allocation....

  13. EVALUATION OF TWO-LEVEL GLOBAL LOAD BALANCING FRAMEWORK IN CLOUD ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Po-Huei Liang

    2015-05-01

    Full Text Available With technological advancements and constant changes of Internet, cloud computing has been today's trend. With the lower cost and convenience of cloud computing services, users have increasingly put their Web resources and information in the cloud environment. The availability and reliability of the client systems will become increasingly important. Today cloud applications slightest interruption, the impact will be significant for users. It is an important issue that how to ensure reliability and stability of the cloud sites. Load balancing would be one good solution. This paper presents a framework for global server load balancing of the Web sites in a cloud with two-level load balancing model. The proposed framework is intended for adapting an open-source load-balancing system and the framework allows the network service provider to deploy a load balancer in different data centers dynamically while the customers need more load balancers for increasing the availability.

  14. Static load balancing for CFD distributed simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chronopoulos, A T; Grosu, D; Wissink, A; Benche, M

    2001-01-26

    The cost/performance ratio of networks of workstations has been constantly improving. This trend is expected to continue in the near future. The aggregate peak rate of such systems often matches or exceeds the peak rate offered by the fastest parallel computers. This has motivated research towards using a network of computers, interconnected via a fast network (cluster system) or a simple Local Area Network (LAN) (distributed system), for high performance concurrent computations. Some of the important research issues arise such as (1) Optimal problem partitioning and virtual interconnection topology mapping; (2) Optimal execution scheduling and load balancing. CFD codes have been efficiently implemented on homogeneous parallel systems in the past. In particular, the helicopter aerodynamics CFD code TURNS has been implemented with MPI on the IBM SP with parallel relaxation and Krylov iterative methods used in place of more traditional recursive algorithms to enhance performance. In this implementation the space domain is divided into equal subdomain which are mapped to the processors. We consider the implementation of TURNS on a LAN of heterogeneous workstations. In order to deal with the problem of load balancing due to the different processor speeds we propose a suboptimal algorithm of dividing the space domain into unequal subdomains and assign them to the different computers. The algorithm can apply to other CFD applications. We used our algorithm to schedule TURNS on a network of workstations and obtained significantly better results.

  15. Static load balancing for CFD distributed simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chronopoulos, A T; Grosu, D; Wissink, A; Benche, M

    2001-01-26

    The cost/performance ratio of networks of workstations has been constantly improving. This trend is expected to continue in the near future. The aggregate peak rate of such systems often matches or exceeds the peak rate offered by the fastest parallel computers. This has motivated research towards using a network of computers, interconnected via a fast network (cluster system) or a simple Local Area Network (LAN) (distributed system), for high performance concurrent computations. Some of the important research issues arise such as (1) Optimal problem partitioning and virtual interconnection topology mapping; (2) Optimal execution scheduling and load balancing. CFD codes have been efficiently implemented on homogeneous parallel systems in the past. In particular, the helicopter aerodynamics CFD code TURNS has been implemented with MPI on the IBM SP with parallel relaxation and Krylov iterative methods used in place of more traditional recursive algorithms to enhance performance. In this implementation the space domain is divided into equal subdomain which are mapped to the processors. We consider the implementation of TURNS on a LAN of heterogeneous workstations. In order to deal with the problem of load balancing due to the different processor speeds we propose a suboptimal algorithm of dividing the space domain into unequal subdomains and assign them to the different computers. The algorithm can apply to other CFD applications. We used our algorithm to schedule TURNS on a network of workstations and obtained significantly better results.

  16. A comparative experiment in distributed load balancing

    KAUST Repository

    Randles, Martin

    2009-12-01

    The anticipated uptake of Cloud computing, built on the well-established research fields of web services, networks, utility computing, distributed computing and virtualisation, will bring many advantages in cost, flexibility and availability for service users. These benefits are expected to further drive the demand for cloud services, increasing both the cloud customer base and the scale of cloud installations. This has implications for many technical issues in such Service Oriented Architectures and Internet of Services (IoS) type applications; fault tolerance, high availability and scalability for examples. Central to these issues is the establishment of effective load balancing techniques. It is clear that the scale and complexity of these systems makes centralized individual assignment of jobs to specific servers infeasible; leading to the need for an effective distributed solution. This paper investigates three possible distributed solutions, which have been proposed for load balancing: An approach inspired by the foraging behaviour of the Honeybee, Biased Random Sampling and Active Clustering. © 2009 IEEE.

  17. Selective randomized load balancing and mesh networks with changing demands

    Science.gov (United States)

    Shepherd, F. B.; Winzer, P. J.

    2006-05-01

    We consider the problem of building cost-effective networks that are robust to dynamic changes in demand patterns. We compare several architectures using demand-oblivious routing strategies. Traditional approaches include single-hop architectures based on a (static or dynamic) circuit-switched core infrastructure and multihop (packet-switched) architectures based on point-to-point circuits in the core. To address demand uncertainty, we seek minimum cost networks that can carry the class of hose demand matrices. Apart from shortest-path routing, Valiant's randomized load balancing (RLB), and virtual private network (VPN) tree routing, we propose a third, highly attractive approach: selective randomized load balancing (SRLB). This is a blend of dual-hop hub routing and randomized load balancing that combines the advantages of both architectures in terms of network cost, delay, and delay jitter. In particular, we give empirical analyses for the cost (in terms of transport and switching equipment) for the discussed architectures, based on three representative carrier networks. Of these three networks, SRLB maintains the resilience properties of RLB while achieving significant cost reduction over all other architectures, including RLB and multihop Internet protocol/multiprotocol label switching (IP/MPLS) networks using VPN-tree routing.

  18. Load Balancing As A Service In Openstack-Liberty

    Directory of Open Access Journals (Sweden)

    Rashmi T V

    2015-08-01

    Full Text Available Cloud computing is a technology which provides computing resource on demand over the internet as a service. To meet this many opensource cloud operating system are provided for the tenants in order to get useful services from the cloud. There are many opensource cloud OS like AWS Open Shift HP OpenStack etc. Out of all these OpenStack comes with free of cost and it has got a huge community. It can be installed and deploy in private institution or company with free of cost. This paper provides a model and techniques for the dynamic load balancing in OpenStack for managing the trafficloads among the Virtual Machines. The main purpose is to increase the utilization of computing resources and minimize the traffic. Load Balancing as a Service is one of the main service in OpenStack Networking. OpenStack is an opensource platform which provides Infrastructure as a Service. It allows userstenants tocreate their own private clouds and to deploy Virtual Machines which manages different workloads. In this paper we provide an architecture of openstack LBaaS for dynamic load balancing in open stack cloud deployment.

  19. Scalable load-balance measurement for SPMD codes

    Energy Technology Data Exchange (ETDEWEB)

    Gamblin, T; de Supinski, B R; Schulz, M; Fowler, R; Reed, D

    2008-08-05

    Good load balance is crucial on very large parallel systems, but the most sophisticated algorithms introduce dynamic imbalances through adaptation in domain decomposition or use of adaptive solvers. To observe and diagnose imbalance, developers need system-wide, temporally-ordered measurements from full-scale runs. This potentially requires data collection from multiple code regions on all processors over the entire execution. Doing this instrumentation naively can, in combination with the application itself, exceed available I/O bandwidth and storage capacity, and can induce severe behavioral perturbations. We present and evaluate a novel technique for scalable, low-error load balance measurement. This uses a parallel wavelet transform and other parallel encoding methods. We show that our technique collects and reconstructs system-wide measurements with low error. Compression time scales sublinearly with system size and data volume is several orders of magnitude smaller than the raw data. The overhead is low enough for online use in a production environment.

  20. 一维高效动态负载平衡方法:多层均权法%High Efficient One Dimensional Dynamical Load Balancing Method: Multilevel Averaging Weight Method

    Institute of Scientific and Technical Information of China (English)

    莫则尧

    2001-01-01

    A Multilevel Averaging Weight (MAW) dynamic load balancing method suitable for both synchronous and heterogeneous parallel computing environments is presented in this paper to solve the one-dimensional dynamic load imbalance problems arising from the parallel Lagrange numerical simulation of multiple matters non-steady fluid dynamics. At first, a one-dimensional load imbalance model is designed to simplify the theoretical analysis for the robustness of MAW method. For this model, the defined domain is uniformly differenced into grid cells, and every grid cells is assumed to be processed with different CPU time. Given P processors, it is required to find the efficient domain decomposition strategy which can keep the loads among different subdomains assigned to individual processors balanced. Secondly, we present a load balancing method, Averaging Weight (AW) method. The theoretical analysis shows that, while the number the processors is equal to 2, AW method is very efficient to adjust the system form a very imbalanced state to a very balanced state in 2—4 iterations. It is unfortunately that this conclusion can not be generalized to be suitable for larger number of processors. In further, inherited form the idea of the AW method, we designed another load balancing method, Multilevel Averaging Weight method. The similar theoretical analysis shows that this method can adjust the load to be balanced in ClogP iterations for any number of processors, where P is the number of processors and C is the iterations using AW method while P=2. This result is usually enough to efficiently track fluctuations in the load imbalance as the parallel numerical simulation progresses. Moreover, both AW and MAW method are all suitable for both homogeneous and heterogeneous parallel computing environments. Thirdly, we organize the numerical experiments for three types of load balancing models, and gain the same conclusions coincided with that of the theoretical analysis. At last, we

  1. A grid-based virtual reactor: Parallel performance and adaptive load balancing

    NARCIS (Netherlands)

    Korkhov, V.V.; Krzhizhanovskaya, V.V.; Sloot, P.M.A.

    2008-01-01

    We address the problem of porting parallel distributed applications from static homogeneous cluster environments to dynamic heterogeneous Grid resources. We introduce a generic technique for adaptive load balancing of parallel applications on heterogeneous resources and evaluate it using a case

  2. Simulation model of load balancing in distributed computing systems

    Science.gov (United States)

    Botygin, I. A.; Popov, V. N.; Frolov, S. G.

    2017-02-01

    The availability of high-performance computing, high speed data transfer over the network and widespread of software for the design and pre-production in mechanical engineering have led to the fact that at the present time the large industrial enterprises and small engineering companies implement complex computer systems for efficient solutions of production and management tasks. Such computer systems are generally built on the basis of distributed heterogeneous computer systems. The analytical problems solved by such systems are the key models of research, but the system-wide problems of efficient distribution (balancing) of the computational load and accommodation input, intermediate and output databases are no less important. The main tasks of this balancing system are load and condition monitoring of compute nodes, and the selection of a node for transition of the user’s request in accordance with a predetermined algorithm. The load balancing is one of the most used methods of increasing productivity of distributed computing systems through the optimal allocation of tasks between the computer system nodes. Therefore, the development of methods and algorithms for computing optimal scheduling in a distributed system, dynamically changing its infrastructure, is an important task.

  3. A Dynamic and Heuristic Phase Balancing Method for LV Feeders

    Directory of Open Access Journals (Sweden)

    Samad Taghipour Boroujeni

    2016-01-01

    Full Text Available Due to the single-phase loads and their stochastic behavior, the current in the distribution feeders is not balanced. In addition, the single-phase loads are located in different positions along the LV feeders. So the amount of the unbalanced load and its location affect the feeder losses. An unbalanced load causes the feeder losses and the voltage drop. Because of time-varying behavior of the single-phase loads, phase balancing is a dynamic and combinatorial problem. In this research, a heuristic and dynamic solution for the phase balancing of the LV feeders is proposed. In this method, it is supposed that the loads’ tie could be connected to all phases through a three-phase switch. The aim of the proposed method is to make the feeder conditions as balanced as possible. The amount and the location of single-phase loads are considered in the proposed phase balancing method. Since the proposed method needs no communication interface or no remote controller, it is inexpensive, simple, practical, and robust. Applying this method provides a distributed and dynamic phase balancing control. In addition, the feasibility of reducing the used switches is investigated. The ability of the proposed method in the phase balancing of the LV feeders is approved by carrying out some simulations.

  4. Emergency Service Restoration and Load Balancing in Distribution Networks Using Feeder Loadings Balance Index

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sang Yule [Anyang University, Anyang (Korea); Jung, Ho Sung; Shin, Myong Chul [Natural Sciences Campus, Suwon (Korea)

    2002-05-01

    This paper presents an algorithm to obtain an approximate optimal solution for the service restoration and load balancing of large scale radial distribution system in a real-time operation environment. Since the problem is formulated as a combinatorial optimization problem, it is difficult to solve a large-scale combinatorial optimization problem accurately within the reasonable computation time. Therefore, in order to find an approximate optimal solution quickly, the authors proposed an algorithm which combines optimization called cyclic best-first search with heuristic based feeder loadings balance index for computational efficiency and robust performance. To demonstrate the validity of the proposed algorithm, numerical calculations are carried out the KEPCO's 108 bus distribution system. (author). 14 refs., 9 figs., 4 tabs.

  5. Dynamic balance in elite karateka.

    Science.gov (United States)

    Zago, Matteo; Mapelli, Andrea; Shirai, Yuri Francesca; Ciprandi, Daniela; Lovecchio, Nicola; Galvani, Christel; Sforza, Chiarella

    2015-12-01

    In karate, balance control represents a key performance determinant. With the hypothesis that high-level athletes display advanced balance abilities, the purpose of the current study was to quantitatively investigate the motor strategies adopted by elite and non-elite karateka to maintain balance control in competition. The execution of traditional karate techniques (kihon) in two groups of elite Masters (n = 6, 31 ± 19 years) and non-elite Practitioners (n = 4, 25 ± 9 years) was compared assessing body center of mass (CoM) kinematics and other relevant parameters like step width and angular joint behavior. In the considered kihon sequence, normalized average CoM height was 8% lower (p < 0.05), while CoM displacement in the horizontal direction was significantly higher in Masters than in Practitioners (2.5 vs. 1.9 m, p < 0.05), as well as CoM average velocity and rms acceleration (p < 0.05). Step width was higher in Masters in more than half of the sequence steps (p < 0.05). Results suggest that elite karateka showed a refined dynamic balance control, obtained through the increase of the base of support and different maneuvers of lower limbs. The proposed method could be used to objectively detect talented karateka, to measure proficiency level and to assess training effectiveness.

  6. Multipath Load Balancing Routing for Internet of Things

    Directory of Open Access Journals (Sweden)

    Chinyang Henry Tseng

    2016-01-01

    Full Text Available In the next-generation technology, Internet of Things (IoT, billions of smart objects will communicate with one another to make human lives more convenient. IoT is based on wireless sensor network (WSN, and Zigbee is one of the most popular WSN protocols. A mature IoT environment involves heavy WSN data transmission causing bottleneck problems. However, Zigbee’s AODV routing stack does not have load balance mechanism to handle bursty traffic. Therefore, we develop Multipath Load Balancing (MLB Routing to substitute Zigbee’s AODV routing. Our proposed MLB consists of two main designs: LAYER_DESIGN and LOAD_BALANCE. LAYER_DESIGN assigns nodes into different layers based on node distance to IoT gateway. Nodes can have multiple next-hops delivering IoT data. All neighboring layer nodes exchange flow information containing current load, used by LOAD_BALANCE to estimate future load of next-hops. With MLB, nodes can choose the neighbors with the least load as the next-hops and thus can achieve load balance and avoid bottlenecks. Compared with Zigbee’s AODV and multipath version AODV (AOMDV, experiment results demonstrate that MLB achieves better load balance, lower packet loss rate, and better routing connectivity ratio in both grid and random uniform topologies. MLB provides a more convincing routing solution for IoT applications.

  7. An Efficient Diffusion Load Balancing Algorithm in Distributed System

    Directory of Open Access Journals (Sweden)

    Rafiqul Z. Khan

    2014-07-01

    Full Text Available In distributed computing system some nodes are very fast and some are slow and during the computation many fast nodes become idle or under loaded while the slow nodes become over loaded due to the uneven distribution of load in the system. In distributed system, the most common important factor is the information collection about loads on different nodes. The success of load balancing algorithm depends on how quickly the information about the load in the system is collected by a node willing to transfer or accept load. In this paper we have shown that the number of communication overheads depends on the number of overloaded nodes present in the domain of an under loaded nodes and vice-versa. We have also shown that communication overhead for load balancing is always fairly less than KN but in worst case our algorithm’s complexity becomes equal to KN.

  8. 3patial Load Balancing in Nide-Area Wireless Networks

    Institute of Scientific and Technical Information of China (English)

    Kambiz Azarian; Ravindra Patwardhan; Chris Lott; Donna Ghosh; Radhika Gowaikar; Rashid Attar

    2011-01-01

    Load balancing is typically used in the frequency domain of cellular wireless networks to balance paging, access, and traffic load across the available bandwidth. In this paper, we extend load balancing into the spatial domain, and we develop two approaches--network load balancing and single-carrier multilink--for spatial load balancing. Although these techniques are mostly applied to cellular wireless networks and Wi-Fi networks, we show how they can be applied to EV-DO, a 3G cellular data network. When a device has more than one candidate server, these techniques can be used to determine the quality of the channel between a server and the device and to determine the Ipad on each server. The proposed techniques leverage the advantages of existing EV-DO network architecture and are fully backward compatible. Network operators can substantially increase network capacity and improve user experience by using these techniques. Combining load balancing in the frequency and spatial domains improves connectivity within a network and allows resources to be optimally allocated according to the p-fair criterion. Combined load balancing further improves performance.

  9. Partitioning based Approach for Load Balancing Public Cloud

    Directory of Open Access Journals (Sweden)

    T.V V S S C Divya

    2016-05-01

    Full Text Available Load Balancing Model Based on Cloud Partitioning for the Public Cloud environment has an important impact on the performance of network load. A cloud computing system which does not use load balancing has numerous drawbacks. Now-a-days the usage of internet and related resources has increased widely. Due to this there is tremendous increase in workload. So there is uneven distribution of this workload which results in server overloading and may crash. In such systems the resources are not optimally used. Due to this the performance degrades and efficiency reduces. Cloud computing efficient and improves user satisfaction. This project is a better load balance model for public cloud based on the cloud partitioning concept with a switch mechanism to choose different strategies for different situations. The algorithm applies the game theory for load balancing strategy to improve the efficiency in the public cloud environment

  10. Dynamic load balancing scheduling strategy against vulnerability in P2P sub-domain network%P2P分域网络动态负载均衡调度的抗脆弱性策略

    Institute of Scientific and Technical Information of China (English)

    王建勇; 李玉玲; 景秀; 刘峰

    2011-01-01

    The hubs in P2P network increase the network vulnerability.To reduce this kind of vulnerability, a dynamically scheduling strategy for network load balancing is proposed, in which, a P2P network is devided into several domains according to the physical location of P2P nodes, and then it designs a function which can quantify the load of nodes equitably and dynamically.When a consumer node sends a downloading request, the node with the smallest dynamic factor is selected as a server node, which can balance the load of P2P network effectively.Simulations show that this strategy can avoid the forming of hubs,enhance the robustness of network,and make P2P networks develop sustainably and healthily.%P2P网络中集散节点的存在加重了网络的脆弱性.提出一种动态负载均衡调度的抗脆弱性策略,该策略依据节点物理位置的邻近性对网络进行了分域,并设计出更为公平的函数对节点的负载进行动态的量化,当消费节点发出下载请求后,选择负载动态变化因子最小的节点作为服务节点,避免了单个节点负载猛增的情况,均衡了节点的负载.仿真证明该策略能有效抑制网络中集散节点的形成,增强网络的健壮性,从而达到保障P2P网络可持续健康发展的目的.

  11. Ant colony Optimization: A Solution of Load balancing in Cloud

    Directory of Open Access Journals (Sweden)

    Ratan Mishra

    2012-05-01

    Full Text Available As the cloud computing is a new style of computing over internet. It has many advantages along with some crucial issues to be resolved in order to improve reliability of cloud environment. These issues are related with the load management, fault tolerance and different security issues in cloud environment. In this paper the main concern is load balancing in cloud computing. The load can be CPU load, memory capacity, delay or network load. Load balancing is the process of distributing the load among various nodes of adistributed system to improve both resource utilization and job response time while also avoiding a situation where some of the nodes are heavily loaded while other nodes are idle or doing very little work. Load balancing ensures that all the processor in the system or every node in the network does approximately the equal amount of work at any instant of time. Many methods to resolve this problem has been came into existence like Particle Swarm Optimization, hash method, genetic algorithms and severalscheduling based algorithms are there. In this paper we are proposing a method based on Ant Colony optimization to resolve the problem of load balancing in cloud environment.

  12. The Study On Load Balancing Strategies In Distributed Computing System

    Directory of Open Access Journals (Sweden)

    Md. Firoj Ali

    2012-05-01

    Full Text Available A number of load balancing algorithms were developed in order to improve the execution of a distributed application in any kind of distributed architecture. Load balancing involves assigning tasks to each processor and minimizing the execution time of the program. In practice, it would be possible even to execute the applications on any machine of worldwide distributed systems. However, the ‘distributed system’ becomes popular and attractive with the introduction of the web. This results in a significant performance improvement for the users. This paper describes the necessary, newly developed, principal concepts for several load balancing techniques in a distributed computing environment. This paper also includes various types of load balancing strategies, their merits, demerits and comparison depending on certain parameters.

  13. An Efficient Load Balancing Mechanism in Distributed Virtual Environments

    National Research Council Canada - National Science Library

    Jang, Su Min; Yoo, Jae Soo

    2008-01-01

    .... An important issue in this system is effective scalability as the number of users increases. However, it is hard to provide suitable load balancing because of the unpredictable movements of users and hot‐spot locations...

  14. Efficient Approach for Load Balancing in Virtual Cloud Computing Environment

    Directory of Open Access Journals (Sweden)

    Harvinder singh

    2014-10-01

    Full Text Available Cloud computing technology is changing the focus of IT world and it is becoming famous because of its great characteristics. Load balancing is one of the main challenges in cloud computing for distributing workloads across multiple computers or a computer cluster, network links, central processing units, disk drives, or other resources. Successful load balancing optimizes resource use, maximizes throughput, minimizes response time, and avoids overload. The objective of this paper to propose an approach for scheduling algorithms that can maintain the load balancing and provides better improved strategies through efficient job scheduling and modified resource allocation techniques. The results discussed in this paper, based on existing round robin, least connection, throttled load balance, fastest response time and a new proposed algorithm fastest with least connection scheduling algorithms. This new algorithm identifies the overall response time and data centre processing time is improved as well as cost is reduced in comparison to the existing scheduling parameters.

  15. EFFICIENT APPROACH FOR LOAD BALANCING IN VIRTUAL CLOUD COMPUTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Harvinder Singh

    2015-10-01

    Full Text Available Cloud computing technology is changing the focus of IT world and it is becoming famous because of its great characteristics. Load balancing is one of the main challenges in cloud computing for distributing workloads across multiple computers or a computer cluster, network links, central processing units, disk drives, or other resources. Successful load balancing optimizes resource use, maximizes throughput, minimizes response time, and avoids overload. The objective of this paper to propose an approach for scheduling algorithms that can maintain the load balancing and provides better improved strategies through efficient job scheduling and modified resource allocation techniques. The results discussed in this paper, based on existing round robin, least connection, throttled load balance, fastest response time and a new proposed algorithm fastest with least connection scheduling algorithms. This new algorithm identifies the overall response time and data centre processing time is improved as well as cost is reduced in comparison to the existing scheduling parameters.

  16. Task Scheduling Based On Load Balancing Using Artificial Bee Colony In Cloud Computing Environment

    Directory of Open Access Journals (Sweden)

    Fatemeh Rastkhadiv

    2016-12-01

    Full Text Available Cloud computing is a development of distributed computing, parallel computing and grid computing. The aim of cloud computing is providing dynamic leasing of server capabilities as scalable, virtualized services to end users. Resource management as an important issue of cloud computing.Load balancing is a problem of resource management. Recently, Cloud schedulers based on bio-inspired and metaheuristic techniques have been proposed. A good task scheduler should adapt its scheduling strategy to the dynamic environment. Load balancing of nonpreemptive independent tasks on virtual machines is an important aspect of task scheduling in clouds.In this paper, wehave proposeda new cloud scheduler based on load balancing using by Artificial Bee Colonyalgorithm, one of the most popular bio-inspired technique. Artificial bee colony algorithm is an optimization metaheuristic algorithm based on a particular intelligent behavior of honey bee swarms. Our scheduler is designed to achieve well balanced load across virtual machines for maximizing the throughput and deliver to theminimum makespan. The experimental results simulatedusing Cloudsim shows its effectiveness to optimize load balancing and task scheduling compared with both of FCFS and ACO. Our proposed approach allows for more agile task handling while reducing task completion time. Our proposed approach reduces makespan and degree of imbalance.It distributes tasks and makes load balancing between virtual machines. Consequently the proposed algorithm increases performance and resource efficiency.

  17. CORBA负载平衡的研究%Study on CORBA Load Balancing

    Institute of Scientific and Technical Information of China (English)

    骆志刚; 唐雪飞; 刘锦德

    2000-01-01

    CORBA is a widely accepted distributed computing specification,on which interoperability between heterogeneous computer platforms can be accomplished. The performance of CORBA-based appiication system is strongly dependent on object location and manual assignment of objects is impractial.In order to improve performance of CORBA-based distributed system,load-balancing problem must be considered. Firstly,two approaches that can be used tO design load-balanced CORBA application are discussed in detail. On that basis ,a general model of dynamic load balancing based on trading service is proposed. Not only load balancing is implemented in this model ,but also the extension of trading service is transparent to application developers and the original applications can be integrated with it without any modification. At the end,analysis of scalability of this model is given.

  18. Novel load balancing DHT scheme for the heterogeneous system

    Institute of Scientific and Technical Information of China (English)

    Li Yujun; Lu Xianliang; Hou Mengshu

    2008-01-01

    The capacities of the nodes in the peer-to-peer system are strongly heterogeneous,hence one can benefit from distributing the load.based on the capacity of the nodes.At first a model is discussed to evaluate the load balancing of the heterogeneous system,and then a novel load balancing scheme is proposed based on the concept of logical servers and the randomized binary tree,and theoretical guarantees are given.Finally,the feasibility of the scheme using extensive simulations is proven.

  19. 基于规则的分层负载平衡调度模型%A Hierarchical Load Balancing Scheduling Model Based on Rules

    Institute of Scientific and Technical Information of China (English)

    李冬梅; 施海虎; 顾毓清

    2003-01-01

    On a massively parallel and distributed system and a network of workstations system, it is a critical problem to increase the utilization efficiency of resources and the answer speed of tasks by using effective load balancing scheduling strategy. This paper analyzes the scheduling strategy of dynamic load balancing and static load balancing,and then proposes a hierarchical load balancing scheduling model based on rules. Finally,making somecomparisons with Other scheduling models.

  20. Load-balancing algorithms for the parallel community climate model

    Energy Technology Data Exchange (ETDEWEB)

    Foster, I.T.; Toonen, B.R.

    1995-01-01

    Implementations of climate models on scalable parallel computer systems can suffer from load imbalances resulting from temporal and spatial variations in the amount of computation required for physical parameterizations such as solar radiation and convective adjustment. We have developed specialized techniques for correcting such imbalances. These techniques are incorporated in a general-purpose, programmable load-balancing library that allows the mapping of computation to processors to be specified as a series of maps generated by a programmer-supplied load-balancing module. The communication required to move from one map to another is performed automatically by the library, without programmer intervention. In this paper, we describe the load-balancing problem and the techniques that we have developed to solve it. We also describe specific load-balancing algorithms that we have developed for PCCM2, a scalable parallel implementation of the Community Climate Model, and present experimental results that demonstrate the effectiveness of these algorithms on parallel computers. The load-balancing library developed in this work is available for use in other climate models.

  1. COMPREHENSIVE STUDY ON LOAD BALANCING TECHNIQUES IN CLOUD

    Directory of Open Access Journals (Sweden)

    B S Rajeshwari

    2014-06-01

    Full Text Available Due to advancement in technology and growth in human society, it is necessary to work in an environment that reduces cost, utilizes resources effectively, reduces man power and minimizes space utilization. This led to the development of Cloud Computing technology. Cloud computing is a kind of distributed computing with a collection of computing resources located in distributed data centers. It provides massively scalable IT related capabilities to multiple external customers on “pay per use” concept using internet technologies. The increase in the web traffic and different services day by day makes load balancing a critical research topic. Load balancing is one of the central issues in cloud computing. It is the process of distributing the load optimally and evenly among various servers. Proper load balancing in cloud improves the performance factors such as resource utilization, job response time, scalability, throughput, system stability and energy consumption. Many researchers have proposed various load balancing techniques. This paper presents description of various existing centralized and distributed load balancing techniques in cloud environment.

  2. COMPREHENSIVE STUDY ON LOAD BALANCING TECHNIQUES IN CLOUD

    Directory of Open Access Journals (Sweden)

    B S Rajeshwari

    2015-11-01

    Full Text Available Due to advancement in technology and growth in human society, it is necessary to work in an environment that reduces cost, utilizes resources effectively, reduces man power and minimizes space utilization. This led to the development of Cloud Computing technology. Cloud computing is a kind of distributed computing with a collection of computing resources located in distributed data centers. It provides massively scalable IT related capabilities to multiple external customers on "pay per use" concept using internet technologies. The increase in the web traffic and different services day by day makes load balancing a critical research topic. Load balancing is one of the central issues in cloud computing. It is the process of distributing the load optimally and evenly among various servers. Proper load balancing in cloud improves the performance factors such as resource utilization, job response time, scalability, throughput, system stability and energy consumption. Many researchers have proposed various load balancing techniques. This paper presents description of various existing centralized and distributed load balancing techniques in cloud environment.

  3. Unstructured P2P Network Load Balance Strategy Based on Multilevel Partitioning of Hypergraph

    Science.gov (United States)

    Feng, Lv; Chunlin, Gao; Kaiyang, Ma

    2017-05-01

    With rapid development of computer performance and distributed technology, P2P-based resource sharing mode plays important role in Internet. P2P network users continued to increase so the high dynamic characteristics of the system determine that it is difficult to obtain the load of other nodes. Therefore, a dynamic load balance strategy based on hypergraph is proposed in this article. The scheme develops from the idea of hypergraph theory in multilevel partitioning. It adopts optimized multilevel partitioning algorithms to partition P2P network into several small areas, and assigns each area a supernode for the management and load transferring of the nodes in this area. In the case of global scheduling is difficult to be achieved, the priority of a number of small range of load balancing can be ensured first. By the node load balance in each small area the whole network can achieve relative load balance. The experiments indicate that the load distribution of network nodes in our scheme is obviously compacter. It effectively solves the unbalanced problems in P2P network, which also improve the scalability and bandwidth utilization of system.

  4. Efficient Load Balancing Routing Technique for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Mahdi Abdulkader Salem

    2016-05-01

    Full Text Available The mobile ad hoc network (MANET is nothing but the wireless connection of mobile nodes which provides the communication and mobility among wireless nodes without the need of any physical infrastructure or centralized devices such as access point or base station. The communication in MANET is done by routing protocols. There are different categories of routing protocols introduced with different goals and objectives for MANETs such as proactive routing protocols (e.g. DSDV, reactive routing protocols (e.g. ADOV, geographic routing protocols (e.g. GRP, hybrid routing protocols etc. There are two important research problems with such routing protocols to address such as efficient load balancing and energy efficiency. In this paper, we are focusing on evaluation and analysis of efficient load balancing protocol design for MANET. Inefficient load balancing technique results in increasing routing overhead, poor packet delivery ratio, and other Quality of Service (QoS parameters. In literature, there are a number of different methods proposed for improving the performance of routing protocols by efficient load balancing among mobile nodes communication. However, most of the methods suffer from various limitations. In this paper, we propose a novel technique for improved the QoS performance of load balancing approach as well as increasing the network lifetime. Evaluation of Network lifetime is out of scope of this paper.

  5. EFFICIENT VM LOAD BALANCING ALGORITHM FOR A CLOUD COMPUTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Jasmin James

    2012-09-01

    Full Text Available Cloud computing is a fast growing area in computing research and industry today. With the advancement of the Cloud, there are new possibilities opening up on how applications can be built and how different services can be offered to the end user through Virtualization, on the internet. There are the cloud service providers who provide large scaled computing infrastructure defined on usage, and provide the infrastructure services in a very flexiblemanner which the users can scale up or down at will. The establishment of an effective load balancing algorithm and how to use Cloud computing resources efficiently for effective and efficient cloud computing is one of the Cloud computing service providers’ultimate goals. In this paper firstly analysis of different Virtual Machine (VM load balancing algorithms is done. Secondly, a new VM load balancing algorithm has been proposed and implemented for an IaaS framework in Simulated cloud computing environment; i.e. ‘Weighted Active Monitoring Load Balancing Algorithm’ using CloudSimtools, for the Datacenter to effectively load balance requests between the available virtual machines assigning a weight, in order to achieve better performance parameters such as response time and Data processing time.

  6. Query Load Balancing For Visible Object Extraction

    DEFF Research Database (Denmark)

    Bukauskas, Linas; Bøhlen, Michael Hanspeter

    2004-01-01

    Interactive visual data explorations impose rigid real-time requirements on the extraction of visible objects. Often these requirements are met by deploying powerful hardware that maintains the entire data set in huge main memory structures. In this paper we propose an approach that retrieves...... objects along the path. The visible objects are retrieved incrementally, and it is possible to precisely control the query load and the number of retrieved objects. The minimal distance path method issues frequent queries and retrieves the lowest possible number of objects at each query point. The end...

  7. Dynamic load balancing based on restricted multicast tree in triplet-based hierarchical interconnection network%基三分层互连网络中基于受限多播树的动态负载平衡

    Institute of Scientific and Technical Information of China (English)

    刘滨; 石峰; 高玉金; 计卫星; 宋红

    2008-01-01

    To solve the load balancing problem in a triplet-based hierarchical interconnection network(THIN)system,a dynamic load balancing(DLB)algorithm-THINDLBA,which adopts multicast tree(MT)technology to improve the efficiency of interchanging load information,is presented.To support the algorithm,a complete set of DLB messages and a schema of maintaining DLB information in each processing node are designed.The load migration request messages from the heavily loaded node(HLN)are spread along an MT whose root is the HLN.And the lightly loaded nodes(LLNs) covered by the MT are the candidate destinations of load migration; the load information interchanged between the LLNs and the HLN can be transmitted along the MT.So the HLN can migrate excess loads out as many as possible during a one time execution of the THINDLBA,and its load state can be improved as quickly as possible.To avoid wrongly transmitted or redundant DLB messages due to MT overlapping,the MT construction is restricted in the design of the THINDLBA.Through experiments,the effectiveness of four DLB algorithms are compared,and the results show that the THINDLBA can effectively decrease the time costs of THIN systems in dealing with large scale compute-intensive tasks more than others.%为了解决基三分层互连网络(THIN)系统中的负载平衡问题,提出一种采用多播树技术提高节点间交换负载信息效率的动态负载平衡(DLB)算法--THINDLBA.设计了一套完整的DLB消息和各节点处的信息维护机制以辅助算法实现.重载节点的负载迁移请求消息沿着一棵以该节点为根的多播树传播,被该树覆盖的轻载节点均成为负载迁移的候选目标节点,可以沿着该树和重载节点交互负载信息,从而使重载节点能够在算法的一次执行中外迁最多的过载进程,尽快改善自身负载状态.算法设计中约束了多播树的构造过程,以避免因树间覆盖造成的消息误传或冗余.通过实验对比了4

  8. Dynamic Analysis of a Pendulum Dynamic Automatic Balancer

    Directory of Open Access Journals (Sweden)

    Jin-Seung Sohn

    2007-01-01

    Full Text Available The automatic dynamic balancer is a device to reduce the vibration from unbalanced mass of rotors. Instead of considering prevailing ball automatic dynamic balancer, pendulum automatic dynamic balancer is analyzed. For the analysis of dynamic stability and behavior, the nonlinear equations of motion for a system are derived with respect to polar coordinates by the Lagrange's equations. The perturbation method is applied to investigate the dynamic behavior of the system around the equilibrium position. Based on the linearized equations, the dynamic stability of the system around the equilibrium positions is investigated by the eigenvalue analysis.

  9. Load Balancing in Stochastic Networks: Algorithms, Analysis, and Game Theory

    Science.gov (United States)

    2014-04-16

    SECURITY CLASSIFICATION OF: The classic randomized load balancing model is the so-called supermarket model, which describes a system in which...balancing model is the so-called supermarket model, which describes a system in which customers arrive to a service center with n parallel servers according...significantly reduces the total cost to the system . In fact, for a given ? and marginal cost of sampling, the threshold supermarket model always outperforms the

  10. Load Balancing in Partner-Based Scheduling Algorithm for Grid Workflow

    Directory of Open Access Journals (Sweden)

    Muhammad Roman

    2016-05-01

    Full Text Available Automated advance reservation has the potential to ensure a good scheduling solution in computational Grids. To improve global throughput of Grid system and enhance resource utilization, workload has to be distributed among the resources of the Grid evenly. This paper discusses the problem of load distribution and resource utilization in heterogeneous Grids in advance reservation environment. We have proposed an extension of Partner Based Dynamic Critical Path for Grids algorithm named Balanced Partner Based Dynamic Critical Path for Grids (B-PDCPG that incorporates a hybrid and threshold based mechanism to achieve load balancing to an allowed value of variation in workload among the resources in Partner Based Dynamic Critical Path for Grids algorithm. The proposed load balancing technique uses Utilization Profiles to store the reservation details and check the loads from these profiles on each of the resources and links. The load is distributed among resources based on the processing element capacity and number of processing units on resources. The simulation results, using Gridsim simulation engine, show that the proposed technique has balanced the workload very effectively and has provided better utilization of resources while decreasing the workflow makespan.

  11. Geographic Load Balanced Routing in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Robin Guleria

    2013-06-01

    Full Text Available Recently the application domains of wireless sensor networks have grown exponentially. Traditional routing algorithm generates traffic related to route discovery to destination. Geographic routing algorithms exploit location information well but the problem of congestion and collision throttle its full employment for resource constrained wireless sensor networks. In this paper we present a Geographic Load Balanced Routing (GLBR, explores a technique Load balancing for WSNs which can be a viable solution to the challenges of geographic routing. Load balancing can be realized through two approaches. GLBR defines parameters based on communication overhead at sensor nodes and wireless link status through which load can be balanced across whole network. GLBR approach exploits the existing Geographic Routing approach i.e. Greedy forwarding by considering not only the distance between next hop and destination as single parameter for packet forwarding but also consider overhead at node. When load at a node is high GLBR looks for an alternate option for packet forwarding. Thus GLBR divert traffic to obviate congestion and hence avoid disconnections in the network.

  12. A novel load balancing method for hierarchical federation simulation system

    Science.gov (United States)

    Bin, Xiao; Xiao, Tian-yuan

    2013-07-01

    In contrast with single HLA federation framework, hierarchical federation framework can improve the performance of large-scale simulation system in a certain degree by distributing load on several RTI. However, in hierarchical federation framework, RTI is still the center of message exchange of federation, and it is still the bottleneck of performance of federation, the data explosion in a large-scale HLA federation may cause overload on RTI, It may suffer HLA federation performance reduction or even fatal error. Towards this problem, this paper proposes a load balancing method for hierarchical federation simulation system based on queuing theory, which is comprised of three main module: queue length predicting, load controlling policy, and controller. The method promotes the usage of resources of federate nodes, and improves the performance of HLA simulation system with balancing load on RTIG and federates. Finally, the experiment results are presented to demonstrate the efficient control of the method.

  13. A grid-based virtual reactor: Parallel performance and adaptive load balancing

    NARCIS (Netherlands)

    Korkhov, V.V.; Krzhizhanovskaya, V.V.; Sloot, P.M.A.

    2008-01-01

    We address the problem of porting parallel distributed applications from static homogeneous cluster environments to dynamic heterogeneous Grid resources. We introduce a generic technique for adaptive load balancing of parallel applications on heterogeneous resources and evaluate it using a case stud

  14. Scan-directed load balancing for highly-parallel mesh-connected computers. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Biagioni, E.S.; Prins, J.F.

    1991-07-01

    Scan Directed Load Balancing is a new, locality-preserving, dynamic load balancing algorithm for grid based computations on mesh connected parallel computers. Scans are used to efficiently determine what areas of the machine are heavily loaded and what areas are lightly loaded, and to organize the movement of data. Data is shifted along the mesh in a regular fashion to balance the load. The Locality Property of the algorithm guarantees that all the neighbors of a data point on the grid are stored either on the same processor, or on a processor that is directly connected to it. Scan Directed Load Balancing is applicable to both SIMD and MIMD mesh-connected parallel computers, and has been implemented on the MasPar MP-1. The authors present some theoretical bounds achieved by the algorithm as well as the algorithm's performance on a particular image processing problem, edge-directed diffusion. Their experiments show that the algorithm is effective in improving the load distribution for real problems, while the efficiency of the original grid-based computation is preserved by the locality property.

  15. Mobility-Aware and Load Balancing Based Clustering Algorithm for Energy Conservation in MANET

    Institute of Scientific and Technical Information of China (English)

    XU Li; ZHENG Bao-yu; GUO Gong-de

    2005-01-01

    Mobile ad hoc network (MANET) is one of wireless communication network architecture that has received a lot of attention. MANET is characterized by dynamic network topology and limited energy. With mobility-aware and load balancing based clustering algorithm (MLCA), this paper proposes a new topology management strategy to conserve energy. Performance simulation results show that the proposed MLCA strategy can balances the traffic load inside the whole network, so as to prolong the network lifetime, meanly, at the same time, achieve higher throughput ratio and network stability.

  16. Performance Evaluation of Modified AODV for Load Balancing

    Directory of Open Access Journals (Sweden)

    Amita Rani

    2007-01-01

    Full Text Available AODV is a prominent routing protocol for MANET that uses hop count as a path selection metric. However, AODV has no means to convey traffic load on current route. This study focuses on introducing a new metric, Aggregate Interface Queue Length (AIQL, in AODV in order to deal with load balancing issues. Performance evaluation through simulation shows that the modified code can perform better than the conventional AODV. We also evaluate the effect of interface queue length on normalized routing load, average throughput and average end-to-end delay.

  17. Architectural Review of Load Balancing Single System Image

    Directory of Open Access Journals (Sweden)

    B. S. Ahmed

    2008-01-01

    Full Text Available Problem statement: With the growing popularity of clustering application combined with apparent usability, the single system image is in the limelight and actively studied as an alternative solution for computational intensive applications as well as the platform for next evolutionary grid computing era. Approach: Existing researches in this field concentrated on various features of Single System Images like file system and memory management. However, an important design consideration for this environment is load allocation and balancing that is usually handled by an automatic process migration daemon. Literature shows that the design concepts and factors that affect the load balancing feature in an SSI system are not clear. Result: This study will review some of the most popular architecture and algorithms used in load balancing single system image. Various implementations from the past to present will be presented while focusing on the factors that affect the performance of such system. Conclusion: The study showed that although there are some successful open source systems, the wide range of implemented systems investigated that research activity should concentrate on the systems that have already been proposed and proved effectiveness to achieve a high quality load balancing system.

  18. A Hierarchical Load Balancing Policy for Grid Computing Environment

    Directory of Open Access Journals (Sweden)

    Said Fathy El Zoghdy

    2012-06-01

    Full Text Available With the rapid development of high-speed wide-area networks and powerful yet low-cost computational resources, grid computing has emerged as an attractive computing paradigm. It provides resources for solving large scientific applications. It is typically composed of heterogeneous resources such as clusters or sites at different administrative domains connected by networks with widely varying performance characteristics. The service level of the grid software infrastructure provides two essential functions for workload and resource management. To efficiently utilize the resources at these environments, effective load balancing and resource management policies are fundamentally important. This paper addresses the problem of load balancing and task migration in grid computing environments. We propose a fully decentralized two-level load balancing policy for computationally intensive tasks on a heterogeneous multi-cluster grid environment. It resolves the single point of failure problem which many of the current policies suffer from. In this policy, any site manager receives two kinds of tasks namely, remote tasks arriving from its associated local grid manager, and local tasks submitted directly to the site manager by local users in its domain, which makes this policy closer to reality and distinguishes it from any other similar policy. It distributes the grid workload based on the resources occupation ratio and the communication cost. The grid overall mean task response time is considered as the main performance metric that need to be minimized. The simulation results show that the proposed load balancing policy improves the grid overall mean task response time.

  19. Cloud Task Scheduling for Load Balancing based on Intelligent Strategy

    Directory of Open Access Journals (Sweden)

    Arabi E. keshk

    2014-04-01

    Full Text Available Cloud computing is a type of parallel and distributed system consisting of a collection of interconnected and virtual computers. With the increasing demand and benefits of cloud computing infrastructure, different computing can be performed on cloud environment. One of the fundamental issues in this environment is related to task scheduling. Cloud task scheduling is an NP-hard optimization problem, and many meta-heuristic algorithms have been proposed to solve it. A good task scheduler should adapt its scheduling strategy to the changing environment and the types of tasks. In this paper a cloud task scheduling policy based on ant colony optimization algorithm for load balancing compared with different scheduling algorithms has been proposed. Ant Colony Optimization (ACO is random optimization search approach that will be used for allocating the incoming jobs to the virtual machines. The main contribution of our work is to balance the system load while trying to minimizing the make span of a given tasks set. The load balancing factor, related to the job finishing rate, is proposed to make the job finishing rate at different resource being similar and the ability of the load balancing will be improved. The proposed scheduling strategy was simulated using Cloudsim toolkit package. Experimental results showed that, the proposed algorithm outperformed scheduling algorithms that are based on the basic ACO or Modified Ant Colony Optimization (MACO.

  20. Reimplementing the LBD DNS Load Balancer with concurrency in GO

    CERN Document Server

    CERN. Geneva

    2016-01-01

    Using the current configuration with 430 aliases, today’s implementation of the LBD DNS Load Balancer does one cycle through all aliases in around 240 seconds. We have a scalability limit of 300 seconds - that is the update period of most aliases. This talk will present a PoC showing how the time could be reduced to just 12 seconds.

  1. Beryllium strain under dynamic loading

    Directory of Open Access Journals (Sweden)

    Pushkov Victor

    2015-01-01

    Full Text Available There are some data (not much on dynamic characteristics of beryllium that are important, for example, when estimating construction performance at NPP emergencies. A number of data on stress-strain curves, spall strength, shear strength, fracture and structure responses of shock loaded beryllium have obtained in US and Russian laboratories. For today the model description of this complex metal behavior does not have a reasonable agreement with the experimental data, thus a wider spectrum of experimental data is required. This work presents data on dynamic compression-test diagrams of Russian beryllium. Experiments are performed using Hopkinson bar method (SHPB. Strain rates were ε ∼ 103 s−1.

  2. A strategy for load balancing in distributed storage systems

    CERN Document Server

    CERN. Geneva

    2012-01-01

    Distributed storage systems are critical to the operation of the WLCG. These systems are not limited to fulfilling the long term storage requirements. They also serve data for computational analysis and other computational jobs. Distributed storage systems provide the ability to aggregate the storage and IO capacity of disks and tapes, but at the end of the day IO rate is still bound by the capabilities of the hardware, in particular the hard drives. Throughput of hard drives has increased dramatically over the decades, however for computational analysis IOPS is typically the limiting factor. To maximize return of investment, balancing IO load over available hardware is crucial. The task is made complicated by the common use of heterogeneous hardware and software environments that results from combining new and old hardware into a single storage system. This paper describes recent advances made in load balancing in the dCache distributed storage system. We describe a set of common requirements for load balan...

  3. A Load Balance Routing Algorithm Based on Uneven Clustering

    Directory of Open Access Journals (Sweden)

    Liang Yuan

    2013-10-01

    Full Text Available Aiming at the problem of uneven load in clustering Wireless Sensor Network (WSN, a kind of load balance routing algorithm based on uneven clustering is proposed to do uneven clustering and calculate optimal number of clustering. This algorithm prevents the number of common node under some certain cluster head from being too large which leads load to be overweight to death through even node clustering. It constructs evaluation function which can better reflect residual energy distribution of nodes and at the same time constructs routing evaluation function between cluster heads which uses MATLAB to do simulation on the performance of this algorithm. Simulation result shows that the routing established by this algorithm effectively improves network’s energy balance and lengthens the life cycle of network.  

  4. Local Dynamic Stability Associated with Load Carrying

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2013-03-01

    Conclusion: Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying.

  5. Distributed Large Dataset Deployment with Improved Load Balancing and Performance

    Directory of Open Access Journals (Sweden)

    Siddharth Bhandari

    2016-08-01

    Full Text Available Cloud computing is a prototype for permitting universal, appropriate, on-demand network access. Cloud is a method of computing where enormously scalable IT-enabled proficiencies are delivered „as a service‟ using Internet tools to multiple outdoor clients. Virtualization is the establishment of a virtual form of something such as computing device or server, an operating system, or network devices and storage device. The different names for cloud data management are DaaS Data as a service, Cloud Storage, and DBaaS Database as a service. Cloud storage permits users to store data, information in documents formats. iCloud, Google drive, Drop box, etc. are most common and widespread cloud storage methods. The main challenges connected with cloud database are fault tolerance, scalability, data consistency, high availability and integrity, confidentiality and many more. Load balancing improves the performance of the data center. We propose an architecture which provides load balancing to the cloud database. We introduced a load balancing server which calculates the load of the data center using our proposed algorithm and distributes the data accordingly to the different data centers. Experimental results showed that it also improve the performance of the cloud system

  6. Asymmetry-aware load balancing for parallel applications in single-ISA multi-core systems

    Institute of Scientific and Technical Information of China (English)

    EunsungKIM; Hyeonsang EOM; Heon Y. YEOM

    2012-01-01

    Contemporary operating systems for single-ISA (instruction set architecture) multi-core systems attempt to distribute tasks equally among all the CPUs.This approach works relatively well when there is no difference in CPU capability.However,there are cases in which CPU capability differs from one another.For instance,static capability asymmetry results from the advent of new asymmetric hardware,and dynamic capability asymmetry comes from the operating system (OS) outside noise caused from networking or I/O handling.These asymmetries can make it hard for the OS scheduler to evenly distribute the tasks,resulting in less efficient load balancing.In this paper,we propose a user-level load balancer for parallel applications,called the ‘capability balancer',which recognizes the difference of CPU capability and makes subtasks share the entire CPU capability fairly.The balancer can coexist with the existing kernel-level load balancer without detrimenting the behavior of the kernel balancer.The capability balancer can fairly distribute CPU capability to tasks with very little overhead.For real workloads like the NAS Parallel Benchmark (NPB),we have accomplished speedups of up to 9.8% and 8.5% in dynamic and static asymmetries,respectively.We have also experienced speedups of 13.3 % for dynamic asymmetry and 24.1% for static asymmetry in a competitive environment.The impacts of our task selection policies,FIFO (first in,first out) and cache,were compared.The use of the cache policy led to a speedup of 5.3% in overall execution time and a decrease of 4.7% in the overall cache miss count,compared with the FIFO policy,which is used by default.

  7. Energy-Aware Load Balancing in Content Delivery Networks

    CERN Document Server

    Mathew, Vimal; Shenoy, Prashant

    2011-01-01

    Internet-scale distributed systems such as content delivery networks (CDNs) operate hundreds of thousands of servers deployed in thousands of data center locations around the globe. Since the energy costs of operating such a large IT infrastructure are a significant fraction of the total operating costs, we argue for redesigning CDNs to incorporate energy optimizations as a first-order principle. We propose techniques to turn off CDN servers during periods of low load while seeking to balance three key design goals: maximize energy reduction, minimize the impact on client-perceived service availability (SLAs), and limit the frequency of on-off server transitions to reduce wear-and-tear and its impact on hardware reliability. We propose an optimal offline algorithm and an online algorithm to extract energy savings both at the level of local load balancing within a data center and global load balancing across data centers. We evaluate our algorithms using real production workload traces from a large commercial ...

  8. Transcribing the balanced scorecard into system dynamics

    DEFF Research Database (Denmark)

    Nielsen, Steen; Nielsen, Erland Hejn

    2013-01-01

    the cause-and-effect relationships of an integrated BSC model. Including dynamic aspects of BSCs into the discussion is only in its infancy, so the aim of our work is also to contribute to both scholars’ and practitioners’ general understanding of how such delayed dynamic effects propagate through system......The purpose of this paper is to show how a System Dynamics Modelling approach can be integrated into the Balanced Scorecard (BSC) for a case company with special focus on the handling of causality in a dynamic perspective. The BSC model includes five perspectives and a number of financial and non...

  9. Efficient Load Balancing Techniques for Self-organizing Content Addressable Networks

    Directory of Open Access Journals (Sweden)

    Djelloul Boukhelef

    2010-03-01

    Full Text Available Balancing the load in a decentralized P2P systemis a challenging problem due to the dynamic nature of suchenvironment and the absence of global knowledge about theactual composition of the system.In this paper, we addressthe problem of load balancing in large scale and selforganizingP2P systems managing multidimensional data.We propose simple and efficient decentralized mechanismsto evenly distribute the data load among the participatingnodes in Content Addressable Networks. The basic idea isto enable a new node that joins the system to share the loadwith a heavily loaded node which is already in the system,such that the load is still evenly distributed among all theparticipating nodes. In the multiple random choices method,the new node probes the load of some existing nodes selecteduniformly at random, then chooses the heaviest node amongthem to share the load with. In this paper, we extend thismethod in three ways. First, the new node probes a poolof nodes proportional to the network size and composition.Specifically, the number of probed nodes is logarithmic tothe network size. This property enables to achieve a constantload imbalance factor which is very small without the needto estimate the network size. Second, the probed nodes arenot selected at random, but they are well spread over the keyspace; which enables a good estimation of the actual datadistribution and network composition, which enables to copewell with large-scale data imbalance. Third, the selection ofnodes to probe is restricted to the immediate and distantneighbors of a randomly chosen node. The cost incurred byour join-based load balancing method is very small, sinceall load information is piggybacked to periodic maintenancemessages exchanged between nodes and their neighbors.Unlike other methods, we do not make use of external indexnor assume any global knowledge. We also generalize thefirst method to enable locating a heavily loaded node througha sequential walk starting

  10. GRACOS: Scalable and Load Balanced P3M Cosmological N-body Code

    CERN Document Server

    Shirokov, A; Shirokov, Alexander; Bertschinger, Edmund

    2005-01-01

    We present a parallel implementation of the particle-particle/particle-mesh (P3M) algorithm for distributed memory clusters. The GRACOS (GRAvitational COSmology) code uses a hybrid method for both computation and domain decomposition. Long-range forces are computed using a Fourier transform gravity solver on a regular mesh; the mesh is distributed across parallel processes using a static one-dimensional slab domain decomposition. Short-range forces are computed by direct summation of close pairs; particles are distributed using a dynamic domain decomposition based on a space-filling Hilbert curve. A nearly-optimal method was devised to dynamically repartition the particle distribution so as to maintain load balance even for extremely inhomogeneous mass distributions. Tests using $800^3$ simulations on a 40-processor beowulf cluster showed good load balance and scalability up to 80 processes. We discuss the limits on scalability imposed by communication and extreme clustering and suggest how they may be remove...

  11. Dynamic balance abilities of collegiate men for the bench press.

    Science.gov (United States)

    Piper, Timothy J; Radlo, Steven J; Smith, Thomas J; Woodward, Ryan W

    2012-12-01

    This study investigated the dynamic balance detection ability of college men for the bench press exercise. Thirty-five college men (mean ± SD: age = 22.4 ± 2.76 years, bench press experience = 8.3 ± 2.79 years, and estimated 1RM = 120.1 ± 21.8 kg) completed 1 repetition of the bench press repetitions for each of 3 bar loading arrangements. In a randomized fashion, subjects performed the bench press with a 20-kg barbell loaded with one of the following: a balanced load, one 20-kg plate on each side; an imbalanced asymmetrical load, one 20-kg plate on one side and a 20-kg plate plus a 1.25-kg plate on the other side; or an imbalanced asymmetrical center of mass, 20-kg plate on one side and sixteen 1.25-kg plates on the other side. Subjects were blindfolded and wore ear protection throughout all testing to decrease the ability to otherwise detect loads. Binomial data analysis indicated that subjects correctly detected the imbalance of the imbalanced asymmetrical center of mass condition (p[correct detection] = 0.89, p < 0.01) but did not correctly detect the balanced condition (p[correct detection] = 0.46, p = 0.74) or the imbalanced asymmetrical condition (p[correct detection] = 0.60, p = 0.31). Although it appears that a substantial shift in the center of mass of plates leads to the detection of barbell imbalance, minor changes of the addition of 1.25 kg (2.5 lb) to the asymmetrical condition did not result in consistent detection. Our data indicate that the establishment of a biofeedback loop capable of determining balance detection was only realized under a high degree of imbalance. Although balance detection was not present in either the even or the slightly uneven loading condition, the inclusion of balance training for upper body may be futile if exercises are unable to establish such a feedback loop and thus eliciting an improvement of balance performance.

  12. A Comparative Study of Load Balancing Algorithms in Cloud Computing Environment

    OpenAIRE

    Katyal, Mayanka; Mishra, Atul

    2014-01-01

    Cloud Computing is a new trend emerging in IT environment with huge requirements of infrastructure and resources. Load Balancing is an important aspect of cloud computing environment. Efficient load balancing scheme ensures efficient resource utilization by provisioning of resources to cloud users on demand basis in pay as you say manner. Load Balancing may even support prioritizing users by applying appropriate scheduling criteria. This paper presents various load balancing schemes in differ...

  13. Population-based learning of load balancing policies for a distributed computer system

    Science.gov (United States)

    Mehra, Pankaj; Wah, Benjamin W.

    1993-01-01

    Effective load-balancing policies use dynamic resource information to schedule tasks in a distributed computer system. We present a novel method for automatically learning such policies. At each site in our system, we use a comparator neural network to predict the relative speedup of an incoming task using only the resource-utilization patterns obtained prior to the task's arrival. Outputs of these comparator networks are broadcast periodically over the distributed system, and the resource schedulers at each site use these values to determine the best site for executing an incoming task. The delays incurred in propagating workload information and tasks from one site to another, as well as the dynamic and unpredictable nature of workloads in multiprogrammed multiprocessors, may cause the workload pattern at the time of execution to differ from patterns prevailing at the times of load-index computation and decision making. Our load-balancing policy accommodates this uncertainty by using certain tunable parameters. We present a population-based machine-learning algorithm that adjusts these parameters in order to achieve high average speedups with respect to local execution. Our results show that our load-balancing policy, when combined with the comparator neural network for workload characterization, is effective in exploiting idle resources in a distributed computer system.

  14. Hybrid Bee Ant Colony Algorithm for Effective Load Balancing And ...

    African Journals Online (AJOL)

    PROF. OLIVER OSUAGWA

    Genetic Algorithm (MO-GA) for dynamic job scheduling ... selection of a data centre. 2.2 Load ... An artificial ant colony, that was capable of .... Scheduling in Hybrid Cloud,” International Journal of Engineering and Technology Volume 2. No.

  15. Scalable and balanced dynamic hybrid data assimilation

    Science.gov (United States)

    Kauranne, Tuomo; Amour, Idrissa; Gunia, Martin; Kallio, Kari; Lepistö, Ahti; Koponen, Sampsa

    2017-04-01

    Scalability of complex weather forecasting suites is dependent on the technical tools available for implementing highly parallel computational kernels, but to an equally large extent also on the dependence patterns between various components of the suite, such as observation processing, data assimilation and the forecast model. Scalability is a particular challenge for 4D variational assimilation methods that necessarily couple the forecast model into the assimilation process and subject this combination to an inherently serial quasi-Newton minimization process. Ensemble based assimilation methods are naturally more parallel, but large models force ensemble sizes to be small and that results in poor assimilation accuracy, somewhat akin to shooting with a shotgun in a million-dimensional space. The Variational Ensemble Kalman Filter (VEnKF) is an ensemble method that can attain the accuracy of 4D variational data assimilation with a small ensemble size. It achieves this by processing a Gaussian approximation of the current error covariance distribution, instead of a set of ensemble members, analogously to the Extended Kalman Filter EKF. Ensemble members are re-sampled every time a new set of observations is processed from a new approximation of that Gaussian distribution which makes VEnKF a dynamic assimilation method. After this a smoothing step is applied that turns VEnKF into a dynamic Variational Ensemble Kalman Smoother VEnKS. In this smoothing step, the same process is iterated with frequent re-sampling of the ensemble but now using past iterations as surrogate observations until the end result is a smooth and balanced model trajectory. In principle, VEnKF could suffer from similar scalability issues as 4D-Var. However, this can be avoided by isolating the forecast model completely from the minimization process by implementing the latter as a wrapper code whose only link to the model is calling for many parallel and totally independent model runs, all of them

  16. Balancing organization and flexibility in foraging dynamics.

    Science.gov (United States)

    Tabone, Michaelangelo; Ermentrout, Bard; Doiron, Brent

    2010-10-07

    Proper pattern organization and reorganization are central problems facing many biological networks which thrive in fluctuating environments. However, in many cases the mechanisms that organize system activity oppose those that support behavioral flexibility. Thus, a balance between pattern organization and pattern flexibility is critically important for overall biological fitness. We study this balance in the foraging strategies of ant colonies exploiting food in dynamic environments. We present discrete time and space simulations of colony activity that uses a pheromone-based recruitment strategy biasing foraging towards a food source. After food relocation, the pheromone must evaporate sufficiently before foraging can shift colony attention to a new food source. The amount of food consumed within the dynamic environment depends non-monotonically on the pheromone evaporation time constant-with maximal consumption occurring at a time constant which balances trail formation and trail flexibility. A deterministic, 'mean field' model of pheromone and foragers on trails mimics our colony simulations. This reduced framework captures the essence of the flexibility-organization balance, and relates optimal pheromone evaporation to the timescale of the dynamic environment. We expect that the principles exposed in our study will generalize and motivate novel analysis across a broad range systems biology.

  17. Load Balancing Fat-Tree on Long-Lived Flows:Avoiding Congestion in a Data Center Network

    Institute of Scientific and Technical Information of China (English)

    Wen Gao; Xuyan Li; Boyang Zhou; Chunming Wu

    2014-01-01

    In a data center network (DCN), load balancing is required when servers transfer data on the same path. This is necessary to avoid congestion. Load balancing is challenged by the dynamic transferral of demands and complex routing control. Because of the distributed nature of a traditional network, previous research on load balancing has mostly focused on improving the perfor-mance of the local network; thus, the load has not been optimally balanced across the entire network. In this paper, we propose a novel dynamic load-balancing algorithm for fat-tree. This algorithm avoids congestions to the great possible extent by searching for non-conflicting paths in a centralized way. We implement the algorithm in the popular software-defined networking architecture and evaluate the algorithm ’s performance on the Mininet platform. The results show that our algorithm has higher bisection band-width than the traditional equal-cost multi-path load-balancing algorithm and thus more effectively avoids congestion.

  18. Effect of Selected Balance Exercises on the Dynamic Balance of Children with Visual Impairments

    Science.gov (United States)

    Jazi, Shirin Davarpanah; Purrajabi, Fatemeh; Movahedi, Ahmadreza; Jalali, Shahin

    2012-01-01

    Introduction: Maintaining balance while walking is of utmost importance for individuals with visual impairments because deficits in dynamic balance have been associated with a high risk of falling. Thus, the primary aim of the study presented here was to determine whether balance training effects the dynamic balance of children with visual…

  19. Effect of Selected Balance Exercises on the Dynamic Balance of Children with Visual Impairments

    Science.gov (United States)

    Jazi, Shirin Davarpanah; Purrajabi, Fatemeh; Movahedi, Ahmadreza; Jalali, Shahin

    2012-01-01

    Introduction: Maintaining balance while walking is of utmost importance for individuals with visual impairments because deficits in dynamic balance have been associated with a high risk of falling. Thus, the primary aim of the study presented here was to determine whether balance training effects the dynamic balance of children with visual…

  20. LBR: Load Balancing Routing Algorithm for Wireless Sensor Networks

    Science.gov (United States)

    Daabaj, Khaled; Dixon, Mike; Koziniec, Terry

    2010-06-01

    Homogeneous wireless sensor networks (WSNs) are organized using identical sensor nodes, but the nature of WSNs operations results in an imbalanced workload on gateway sensor nodes which may lead to a hot-spot or routing hole problem. The routing hole problem can be considered as a natural result of the tree-based routing schemes that are widely used in WSNs, where all nodes construct a multi-hop routing tree to a centralized root, e.g., a gateway or base station. For example, sensor nodes on the routing path and closer to the base station deplete their own energy faster than other nodes, or sensor nodes with the best link state to the base station are overloaded with traffic from the rest of the network and experience a faster energy depletion rate than their peers. Routing protocols for WSNs are reliability-oriented and their use of reliability metric to avoid unreliable links makes the routing scheme worse. However, none of these reliability oriented routing protocols explicitly uses load balancing in their routing schemes. Since improving network lifetime is a fundamental challenge of WSNs, we present, in this chapter, a novel, energy-wise, load balancing routing (LBR) algorithm that addresses load balancing in an energy efficient manner by maintaining a reliable set of parent nodes. This allows sensor nodes to quickly find a new parent upon parent loss due to the existing of node failure or energy hole. The proposed routing algorithm is tested using simulations and the results demonstrate that it outperforms the MultiHopLQI reliability based routing algorithm.

  1. Framework to Solve Load Balancing Problem in Heterogeneous Web Servers

    CERN Document Server

    Sharma, Ms Deepti

    2011-01-01

    For popular websites most important concern is to handle incoming load dynamically among web servers, so that they can respond to their client without any wait or failure. Different websites use different strategies to distribute load among web servers but most of the schemes concentrate on only one factor that is number of requests, but none of the schemes consider the point that different type of requests will require different level of processing efforts to answer, status record of all the web servers that are associated with one domain name and mechanism to handle a situation when one of the servers is not working. Therefore, there is a fundamental need to develop strategy for dynamic load allocation on web side. In this paper, an effort has been made to introduce a cluster based frame work to solve load distribution problem. This framework aims to distribute load among clusters on the basis of their operational capabilities. Moreover, the experimental results are shown with the help of example, algorithm...

  2. Cell Load Balancing Schemes for Uncoordinated Heterogeneous Deployment

    DEFF Research Database (Denmark)

    Mihaylov, Mihail; Mihovska, Albena D.; Poulkov, Vladimir

    2013-01-01

    This paper proposes an energy consumption improvement algorithm based on a coefficient determining the reliability of offloading users to a new base station (BS) regarding the additional power needed for them to be compensated during an offload from pico BS (PBS) to macro BS (MBS) in uncoordinated...... deployment of heterogeneous networks (HetNet). The aim of the presented idea is to obtain a cell load balancing scheme and a benchmarking criteria for calculating the efficiency and reliability of taking energy saving management actions, before offloading a user from the BSs leading to an improved energy...

  3. Enhanced active dynamic balancing of the planar robots using a three-rotating-bar balancer

    Directory of Open Access Journals (Sweden)

    Kun Wang

    2016-04-01

    Full Text Available The concept of full compensation against the resultant shaking forces and moments for arbitrary robots using a single active dynamic balancing mechanism is first addressed. And the application principle and general balancing conditions of the active dynamic balancing mechanism are presented. With the purpose of providing detailed description of these problems, a compact planar 3-degree-of-freedom active dynamic balancing mechanism is proposed. The active balancer is composed of three independent rotating bars with their respective actuators. The rotations of the three bars could change their center of gravity positions and then generate balancing forces for the unbalanced robots. Moreover, the changing of the angular acceleration of the bars can also generate a dynamic torque to balance the shaking moment. In order to present more detail of the balancing theory, the structure and kinematic and dynamic analysis of the proposed balancing mechanism are given. Finally, numerical examples illustrate the effectiveness of the proposed three-rotating-bar balancer.

  4. Sustainable Load-Balancing Scheme for Inter-Sensor Convergence Processing of Routing Cooperation Topology

    Directory of Open Access Journals (Sweden)

    Hyun-Woo Kim

    2016-05-01

    Full Text Available Recent advancements in Information Technology (IT have sparked the creation of numerous and diverse types of devices and services. Manual data collection measurement methods have been automated through the use of various wireless or wired sensors. Single sensor devices are included in smart devices such as smartphones. Data transmission is critical for big data collected from sensor nodes, such as Mobile Sensor Nodes (MSNs, where sensors move dynamically according to sensor mobility, or Fixed Sensor Nodes (FSNs, where sensor locations are decided by the users. False data transfer processing of big data results in topology lifespan reduction and data transfer delays. Hence, a variety of simulators and diverse load-balancing algorithms have been developed as protocol verification tools for topology lifespan maximization and effective data transfer processing. However, those previously developed simulators have limited functions, such as an event function for a specific sensor or a battery consumption rate test for sensor deployment. Moreover, since the previous load-balancing algorithms consider only the general traffic distribution and the number of connected nodes without considering the current topology condition, the sustainable load-balancing technique that takes into account the battery consumption rate of the dispersed sensor nodes is required. Therefore, this paper proposes the Sustainable Load-balancing Scheme (SLS, which maximizes the overall topology lifespan through effective and sustainable load-balancing of data transfer among the sensors. SLS is capable of maintaining an effective topology as it considers both the battery consumption rate of the sensors and the data transfer delay.

  5. The Dynamic Balancer electrical safety systems

    Energy Technology Data Exchange (ETDEWEB)

    Konkel, H.

    1997-12-01

    The Pantex Plant Dynamic Balancer is used to identify physical imbalance in some weapon systems. This study was conducted at the request of the US Department of Energy/Albuquerque Operations Office (USDOE/AL) Dynamic Balancer Project Team to identify the electrical conditions required for motor over-speed to occur and to discuss the functions of the various electrical protective features associated with the Dynamic Balancer (DB). As is shown through the development of a fault tree, numerous electrical and human failures are required for over-speed conditions to occur. As directed by the Project Team, no effort was made to develop detailed fault trees for all electrical systems, to quantify basic events in the fault tree, or to develop accident scenarios leading to or resulting from over-speed. The Pantex Building 12-60, Bay 2, facility electrical circuits and grounding are described, and potential hazards are discussed. DB motor over-speed is a safety concern, and therefore, the controls that limit this condition are described and discussed in detail. Other safety-significant electrical circuits are discussed as well. These safety systems also are described in the facility Basis for Interim Operation. A potential for a motor over-speed that is not sensed by the standard safety protective systems does exist. This fault pathway is discussed, and recommendations to mitigate its effect are made.

  6. Transcribing the balanced scorecard into system dynamics

    DEFF Research Database (Denmark)

    Nielsen, Steen; Nielsen, Erland Hejn

    2013-01-01

    The purpose of this paper is to show how a System Dynamics Modelling approach can be integrated into the Balanced Scorecard (BSC) for a case company with special focus on the handling of causality in a dynamic perspective. The BSC model includes five perspectives and a number of financial and non......-financial measures. The overall idea of BSC is to make the strategy operational, as proposed by Kaplan and Norton (2007) and to use the strategy for simulation. Our results indicate that a company may gain great insight from simulation studies. The hypothesised model may be used as the first step in quantifying...... the cause-and-effect relationships of an integrated BSC model. Including dynamic aspects of BSCs into the discussion is only in its infancy, so the aim of our work is also to contribute to both scholars’ and practitioners’ general understanding of how such delayed dynamic effects propagate through system...

  7. Load Balancing in Local Computational Grids within Resource Allocation Process

    Directory of Open Access Journals (Sweden)

    Rouhollah Golmohammadi

    2012-11-01

    Full Text Available A suitable resource allocation method in computational grids should schedule resources in a way that provides the requirements of the users and the resource providers; i.e., the maximum number of tasks should be completed in their time and budget constraints and the received load be distributed equally between resources. This is a decision-making problem, while the scheduler should select a resource from all ones. This process is a multi criteria decision-making problem; because of affect of different properties of resources on this decision. The goal of this decision-making process is balancing the load and completing the tasks in their defined constraints. The proposed algorithm is an analytic hierarchy process based Resource Allocation (ARA method. This method estimates a value for the preference of each resource and then selects the appropriate resource based on the allocated values. The simulations show the ARA method decreases the task failure rate at least 48% and increases the balance factor more than 3.4%.

  8. Strength of concrete structures under dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Kumpyak, O. G., E-mail: ogkumpyak@yandex.ru; Galyautdinov, Z. R., E-mail: gazr@yandex.ru; Kokorin, D. N., E-mail: kokorindenn@yandex.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation)

    2016-01-15

    The use of elastic supports is one the efficient methods of decreasing the dynamic loading. The paper describes the influence of elastic supports on the stress-strain state of steel concrete structures exposed to one-time dynamic loading resulting in failure. Oblique bending beams on elastic supports and their elastic, elastoplastic, and elastoplastic consolidation behavior are considered in this paper. For numerical calculations the developed computer program is used based on the finite element method. Research findings prove high efficiency of elastic supports under dynamic loading conditions. The most effective behavior of elastic supports is demonstrated at the elastoplastic stage. A good agreement is observed between the theoretical and experimental results.

  9. Experimental Performances Analysis of Load Balancing Algorithms in IEEE 802.11

    CERN Document Server

    Salah, Hamdi; Rached, Tourki

    2009-01-01

    In IEEE 802.11, load balancing algorithms (LBA) consider only the associated stations to balance the load of the available access points (APs). However, although the APs are balanced, it causes a bad situation if the AP has a lower signal length (SNR) less than the neighbor APs. So, balance the load and associate one mobile station to an access point without care about the signal to noise ratio (SNR) of the AP cause possibly an unforeseen QoS, such as the bit rate, the end to end delay, the packet loss. In this way, we study an improvement load balancing algorithm with SNR integration at the selection policy.

  10. Dynamic Multi-class Network Loading Problem

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The dynamic network loading problem (DNLP) consists in determining on a congested network, timedependent arc volumes, together with arc and path travel times, given the time varying path flow departure rates over a finite time horizon. The objective of this paper is to present the formulation of an analytical dynamic multiclass network loading model. The model does not require the assumption of the FIFO condition. The existence of a solution to the model is shown.

  11. A DYNAMIC LOAD BALANCING STRATEGY OF META-DATA SERVER SYSTEM BASED ON DIRECTORY MIGRATION AND REPLICATION%基于目录迁移与复制的元数据服务系统动态负载均衡策略

    Institute of Scientific and Technical Information of China (English)

    毕鹏飞; 马良荔; 李刚

    2012-01-01

    Traditional load balancing strategy of state-based meta-data service system usually uses directory migration strategy to achieve the object of a balanced state. But this strategy makes the system easy to produce jitter rising from a new unbalanced state. This paper presents a dynamic load balancing strategy for meta-data service system, it combines the directory migration and directory replication and effectively solves the defect of traditional way in likely causing jitter due to only using directory migration for load balancing, and therefore improves the efficiency and stability of the system.%传统的基于状态的元数据服务系统负载均衡策略通常采用目录迁移策略来达到均衡的目的,然而这种策略易使系统进入新的不均衡状态而产生“抖动”现象.提出一种将目录迁移与目录复制相结合的元数据服务系统动态负载均衡策略,有效解决了传统的单一利用目录迁移来进行负载均衡容易造成“抖动”的缺陷,提高了系统的效率和稳定性.

  12. Load balancing in highly parallel processing of Monte Carlo code for particle transport

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Kenji; Takemiya, Hiroshi [Japan Atomic Energy Research Inst., Tokyo (Japan); Kawasaki, Takuji [Fuji Research Institute Corporation, Tokyo (Japan)

    2001-01-01

    In parallel processing of Monte Carlo(MC) codes for neutron, photon and electron transport problems, particle histories are assigned to processors making use of independency of the calculation for each particle. Although we can easily parallelize main part of a MC code by this method, it is necessary and practically difficult to optimize the code concerning load balancing in order to attain high speedup ratio in highly parallel processing. In fact, the speedup ratio in the case of 128 processors remains in nearly one hundred times when using the test bed for the performance evaluation. Through the parallel processing of the MCNP code, which is widely used in the nuclear field, it is shown that it is difficult to attain high performance by static load balancing in especially neutron transport problems, and a load balancing method, which dynamically changes the number of assigned particles minimizing the sum of the computational and communication costs, overcomes the difficulty, resulting in nearly fifteen percentage of reduction for execution time. (author)

  13. BALANCE

    Science.gov (United States)

    Carmichael, H.

    1953-01-01

    A torsional-type analytical balance designed to arrive at its equilibrium point more quickly than previous balances is described. In order to prevent external heat sources creating air currents inside the balance casing that would reiard the attainment of equilibrium conditions, a relatively thick casing shaped as an inverted U is placed over the load support arms and the balance beam. This casing is of a metal of good thernnal conductivity characteristics, such as copper or aluminum, in order that heat applied to one portion of the balance is quickly conducted to all other sensitive areas, thus effectively preventing the fornnation of air currents caused by unequal heating of the balance.

  14. Combined Load Diagram for a Wind Tunnel Strain-Gage Balance

    Science.gov (United States)

    Ulbrich, N.

    2010-01-01

    Combined Load Diagrams for Direct-Read, Force, and Moment Balances are discussed in great detail in the paper. The diagrams, if compared with a corresponding combined load plot of a balance calibration data set, may be used to visualize and interpret basic relationships between the applied balance calibration loads and the load components at the forward and aft gage of a strain-age balance. Lines of constant total force and moment are identified in the diagrams. In addition, the lines of pure force and pure moment are highlighted. Finally, lines of constant moment arm are depicted. It is also demonstrated that each quadrant of a Combined Load Diagram has specific regions where the applied total calibration force is at, between, or outside of the balance gage locations. Data from the manual calibration of a Force Balance is used to illustrate the application of a Combined Load Diagram to a realistic data set.

  15. A single-stage optical load-balanced switch for data centers.

    Science.gov (United States)

    Huang, Qirui; Yeo, Yong-Kee; Zhou, Luying

    2012-10-22

    Load balancing is an attractive technique to achieve maximum throughput and optimal resource utilization in large-scale switching systems. However current electronic load-balanced switches suffer from severe problems in implementation cost, power consumption and scaling. To overcome these problems, in this paper we propose a single-stage optical load-balanced switch architecture based on an arrayed waveguide grating router (AWGR) in conjunction with fast tunable lasers. By reuse of the fast tunable lasers, the switch achieves both functions of load balancing and switching through the AWGR. With this architecture, proof-of-concept experiments have been conducted to investigate the feasibility of the optical load-balanced switch and to examine its physical performance. Compared to three-stage load-balanced switches, the reported switch needs only half of optical devices such as tunable lasers and AWGRs, which can provide a cost-effective solution for future data centers.

  16. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 and described further in 1972. Several authors have refined this method over...... Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work...

  17. Description and development of the means of a model experiment for load balancing in distributed computing systems

    Science.gov (United States)

    Nagiyev, A. E.; Sherstnyova, A. I.; Botygin, I. A.; Galanova, N. Y.

    2016-06-01

    The results of the statistical model experiments research of various load balancing algorithms in distributed computing systems are presented. Software tools were developed. These tools, which allow to create a virtual infrastructure of distributed computing system in accordance with the intended objective of the research focused on multi-agent and multithreaded data processing were developed. A diagram of the control processing of requests from the terminal devices, providing an effective dynamic horizontal scaling of computing power at peak loads, is proposed.

  18. Scheduling algorithms for saving energy and balancing load

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, Antonios

    2012-08-03

    In this thesis we study problems of scheduling tasks in computing environments. We consider both the modern objective function of minimizing energy consumption, and the classical objective of balancing load across machines. We first investigate offline deadline-based scheduling in the setting of a single variable-speed processor that is equipped with a sleep state. The objective is that of minimizing the total energy consumption. Apart from settling the complexity of the problem by showing its NP-hardness, we provide a lower bound of 2 for general convex power functions, and a particular natural class of schedules called s{sub crit}-schedules. We also present an algorithmic framework for designing good approximation algorithms. For general convex power functions our framework improves the best known approximation-factor from 2 to 4/3. This factor can be reduced even further to 137/117 for a specific well-motivated class of power functions. Furthermore, we give tight bounds to show that our framework returns optimal s{sub crit}-schedules for the two aforementioned power-function classes. We then focus on the multiprocessor setting where each processor has the ability to vary its speed. Job migration is allowed, and we again consider classical deadline-based scheduling with the objective of energy minimization. We first study the offline problem and show that optimal schedules can be computed efficiently in polynomial time for any convex and non-decreasing power function. Our algorithm relies on repeated maximum flow computations. Regarding the online problem and power functions P(s) = s{sup {alpha}}, where s is the processor speed and {alpha} > 1 a constant, we extend the two well-known single-processor algorithms Optimal Available and Average Rate. We prove that Optimal Available is {alpha}{sup {alpha}}-competitive as in the single-processor case. For Average Rate we show a competitive factor of (2{alpha}){sup {alpha}}/2 + 1, i.e., compared to the single

  19. Load Balancing Based on Anycast and Pseudo-Mobility in IPv6

    Institute of Scientific and Technical Information of China (English)

    FENGYanjun; SONGCheng; KANZhigang; MAJian; YERunguo

    2004-01-01

    We proposed a new Load balancing mechanism, called LBAM (Load balancing based on anycast and pseudo-mobility in IPv6), by which sessions can be distributed across a pool of servers for maximum performance. Load balancing is needed in many fields, such as Web server, FTP (File transfer protocol) server and NAT-PT (Network address translation-protocol translation) gateway, and there exist several approaches for load balancing. However, current approaches have problems such as poor scalability, inability to balance session flow,long latency time, and topological constraint on server pools. In this paper, we describe how LBAM works in principle without the above problems. We also present our simulation work using NS-2 and discuss performance comparison between LBAM and other load balancing mechanisms. The results show that LBAM has very advanced performance and scalability. Finally, the ubiquitous applications of LBAM in NGI (Next generation Internet) are presented.

  20. A Load Balancing Algorithm Based on Maximum Entropy Methods in Homogeneous Clusters

    Directory of Open Access Journals (Sweden)

    Long Chen

    2014-10-01

    Full Text Available In order to solve the problems of ill-balanced task allocation, long response time, low throughput rate and poor performance when the cluster system is assigning tasks, we introduce the concept of entropy in thermodynamics into load balancing algorithms. This paper proposes a new load balancing algorithm for homogeneous clusters based on the Maximum Entropy Method (MEM. By calculating the entropy of the system and using the maximum entropy principle to ensure that each scheduling and migration is performed following the increasing tendency of the entropy, the system can achieve the load balancing status as soon as possible, shorten the task execution time and enable high performance. The result of simulation experiments show that this algorithm is more advanced when it comes to the time and extent of the load balance of the homogeneous cluster system compared with traditional algorithms. It also provides novel thoughts of solutions for the load balancing problem of the homogeneous cluster system.

  1. Behaviour of Soil Subjected to Dynamic Loads

    DEFF Research Database (Denmark)

    Bødker, L.

    1998-01-01

    Many geotechnical problems involve design of dynamically loaded foundations. The design criterion fr dynamically loaded foundations is often described in terms of limiting values for the displacements. The displacements in the soil are normally very small when dealing with dynamically loaded...... foundations, and hence it is necessary to know the deformation properties for the soil at very low strain level. The main topic of the project is to increase the knowledge of the behaviour of Danish soils at small strain levels and to extend the laboratory facilities to deal with testing at small strains....... The soil behaviour at very small strain levels is non-linear, and the most common testing technique for this situation is the resonant column technique. One of the aims of this project is to install, check, get familiar with and perform tests on different kinds of Danish soils in a new Drnevich...

  2. 基于动态负载均衡的层次性移动 IPv6路由优化方案%DYNAMIC LOAD BALANCING BASED HMIPv6 ROUTE OPTIMIZATION SCHEME

    Institute of Scientific and Technical Information of China (English)

    范祚至; 张曦煌

    2014-01-01

    Aiming at when MBIPv6 network is overload,there is MAP load distribution imbalance problem,the paper proposes a dynamic MAP load scheduling scheme.In the new scheme,through an introduced computing model,MAP takes bandwidth usage situation as parameters to calculate current load.When network load distribution imbalance is detected,it refers to MN mobile trends to schedule loads among MAPs to properly distribute computing resources in the network in order to optimize network performance.Simulation results illustrate that the scheme can effectively improve the network's entire service quality,shorten communication delay and decrease packet loss rate during the communication process.%针对层次性移动 IPv6网络负载过重时存在的 MAP 负载分配失衡的问题,提出一种动态的 MAP 负载调度方案。方案中,MAP 通过提出的计算模型,以带宽使用情况作为参数计算当前的负载。当检测到网络负载分配失衡时,根据 MN 的移动趋向调度 MAP 之间的负载,使网络中的计算资源合理分配,优化网络性能。仿真结果表明,该方案能有效地改善网络的整体服务质量,降低通信时延和减少通信过程中的丢包率。

  3. Priority-rotating DBA with adaptive load balance for reconfigurable WDM/TDM PON

    Science.gov (United States)

    Xia, Weidong; Gan, Chaoqin; Xie, Weilun; Ni, Cuiping

    2015-12-01

    To the wavelength-division multiplexing/time-division multiplexing passive optical network (WDM/TDM PON) architecture that implements wavelength sharing and traffic redirection, a priority-rotating dynamic bandwidth allocation (DBA) algorithm is proposed in this paper. The priority of each ONU is set and rotated to meet the bandwidth demand and guarantee the fairness among optical network units (ONUs). The bandwidth allocation for priority queues is employed to avoid bandwidth monopolization and over-allocation. The bandwidth allocation for high-loaded situation and redirected traffic are discussed to achieve adaptive load balance over wavelengths and among ONUs. The simulation results show a good performance of the proposed algorithm in throughput rate and average packet delay.

  4. Load Balancing in Cloud Computing Environment Using Improved Weighted Round Robin Algorithm for Nonpreemptive Dependent Tasks.

    Science.gov (United States)

    Devi, D Chitra; Uthariaraj, V Rhymend

    2016-01-01

    Cloud computing uses the concepts of scheduling and load balancing to migrate tasks to underutilized VMs for effectively sharing the resources. The scheduling of the nonpreemptive tasks in the cloud computing environment is an irrecoverable restraint and hence it has to be assigned to the most appropriate VMs at the initial placement itself. Practically, the arrived jobs consist of multiple interdependent tasks and they may execute the independent tasks in multiple VMs or in the same VM's multiple cores. Also, the jobs arrive during the run time of the server in varying random intervals under various load conditions. The participating heterogeneous resources are managed by allocating the tasks to appropriate resources by static or dynamic scheduling to make the cloud computing more efficient and thus it improves the user satisfaction. Objective of this work is to introduce and evaluate the proposed scheduling and load balancing algorithm by considering the capabilities of each virtual machine (VM), the task length of each requested job, and the interdependency of multiple tasks. Performance of the proposed algorithm is studied by comparing with the existing methods.

  5. A Multiconstrained Grid Scheduling Algorithm with Load Balancing and Fault Tolerance.

    Science.gov (United States)

    Keerthika, P; Suresh, P

    2015-01-01

    Grid environment consists of millions of dynamic and heterogeneous resources. A grid environment which deals with computing resources is computational grid and is meant for applications that involve larger computations. A scheduling algorithm is said to be efficient if and only if it performs better resource allocation even in case of resource failure. Allocation of resources is a tedious issue since it has to consider several requirements such as system load, processing cost and time, user's deadline, and resource failure. This work attempts to design a resource allocation algorithm which is budget constrained and also targets load balancing, fault tolerance, and user satisfaction by considering the above requirements. The proposed Multiconstrained Load Balancing Fault Tolerant algorithm (MLFT) reduces the schedule makespan, schedule cost, and task failure rate and improves resource utilization. The proposed MLFT algorithm is evaluated using Gridsim toolkit and the results are compared with the recent algorithms which separately concentrate on all these factors. The comparison results ensure that the proposed algorithm works better than its counterparts.

  6. A Multiconstrained Grid Scheduling Algorithm with Load Balancing and Fault Tolerance

    Directory of Open Access Journals (Sweden)

    P. Keerthika

    2015-01-01

    Full Text Available Grid environment consists of millions of dynamic and heterogeneous resources. A grid environment which deals with computing resources is computational grid and is meant for applications that involve larger computations. A scheduling algorithm is said to be efficient if and only if it performs better resource allocation even in case of resource failure. Allocation of resources is a tedious issue since it has to consider several requirements such as system load, processing cost and time, user’s deadline, and resource failure. This work attempts to design a resource allocation algorithm which is budget constrained and also targets load balancing, fault tolerance, and user satisfaction by considering the above requirements. The proposed Multiconstrained Load Balancing Fault Tolerant algorithm (MLFT reduces the schedule makespan, schedule cost, and task failure rate and improves resource utilization. The proposed MLFT algorithm is evaluated using Gridsim toolkit and the results are compared with the recent algorithms which separately concentrate on all these factors. The comparison results ensure that the proposed algorithm works better than its counterparts.

  7. Dynamic Gust Load Analysis for Rotors

    Directory of Open Access Journals (Sweden)

    Yuting Dai

    2016-01-01

    Full Text Available Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.

  8. Selecting boundary conditions in physiological strain analysis of the femur: Balanced loads, inertia relief method and follower load.

    Science.gov (United States)

    Heyland, Mark; Trepczynski, Adam; Duda, Georg N; Zehn, Manfred; Schaser, Klaus-Dieter; Märdian, Sven

    2015-12-01

    Selection of boundary constraints may influence amount and distribution of loads. The purpose of this study is to analyze the potential of inertia relief and follower load to maintain the effects of musculoskeletal loads even under large deflections in patient specific finite element models of intact or fractured bone compared to empiric boundary constraints which have been shown to lead to physiological displacements and surface strains. The goal is to elucidate the use of boundary conditions in strain analyses of bones. Finite element models of the intact femur and a model of clinically relevant fracture stabilization by locking plate fixation were analyzed with normal walking loading conditions for different boundary conditions, specifically re-balanced loading, inertia relief and follower load. Peak principal cortex surface strains for different boundary conditions are consistent (maximum deviation 13.7%) except for inertia relief without force balancing (maximum deviation 108.4%). Influence of follower load on displacements increases with higher deflection in fracture model (from 3% to 7% for force balanced model). For load balanced models, follower load had only minor influence, though the effect increases strongly with higher deflection. Conventional constraints of fixed nodes in space should be carefully reconsidered because their type and position are challenging to justify and for their potential to introduce relevant non-physiological reaction forces. Inertia relief provides an alternative method which yields physiological strain results.

  9. GRACOS: Scalable and Load Balanced P3M Cosmological N-body Code

    Science.gov (United States)

    Shirokov, Alexander; Bertschinger, Edmund

    2010-10-01

    The GRACOS (GRAvitational COSmology) code, a parallel implementation of the particle-particle/particle-mesh (P3M) algorithm for distributed memory clusters, uses a hybrid method for both computation and domain decomposition. Long-range forces are computed using a Fourier transform gravity solver on a regular mesh; the mesh is distributed across parallel processes using a static one-dimensional slab domain decomposition. Short-range forces are computed by direct summation of close pairs; particles are distributed using a dynamic domain decomposition based on a space-filling Hilbert curve. A nearly-optimal method was devised to dynamically repartition the particle distribution so as to maintain load balance even for extremely inhomogeneous mass distributions. Tests using 800(3) simulations on a 40-processor beowulf cluster showed good load balance and scalability up to 80 processes. There are limits on scalability imposed by communication and extreme clustering which may be removed by extending the algorithm to include adaptive mesh refinement.

  10. Material properties under intensive dynamic loading

    CERN Document Server

    Cherne, Frank J; Zhernokletov, Mikhail V; Glushak, B L; Zocher, Marvin A

    2007-01-01

    Understanding the physical and thermomechanical response of materials subjected to intensive dynamic loading is a challenge of great significance in engineering today. This volume assumes the task of gathering both experimental and diagnostic methods in one place, since not much information has been previously disseminated in the scientific literature.

  11. A novel load balanced energy conservation approach in WSN using biogeography based optimization

    Science.gov (United States)

    Kaushik, Ajay; Indu, S.; Gupta, Daya

    2017-09-01

    Clustering sensor nodes is an effective technique to reduce energy consumption of the sensor nodes and maximize the lifetime of Wireless sensor networks. Balancing load of the cluster head is an important factor in long run operation of WSNs. In this paper we propose a novel load balancing approach using biogeography based optimization (LB-BBO). LB-BBO uses two separate fitness functions to perform load balancing of equal and unequal load respectively. The proposed method is simulated using matlab and compared with existing methods. The proposed method shows better performance than all the previous works implemented for energy conservation in WSN

  12. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    2005-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coe±cients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 [1]and described further in 1972 [2]. Several authors have re¯ned this method...... seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coe±cients of the bearing could be used to ¯nd the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for ¯nding the damping coe±cients in this work...

  13. Effect of Aerobic Loading on Static Balance in Young Athletes

    Science.gov (United States)

    Akyüz, Öznur

    2017-01-01

    The fact that balances can also be a factor in performance distinction between athletes in athletic skills, and is considered to provide positive acceleration for physical development in which motor skills are exhibited. Human's skill to ensure balance can be defined as a determinant factor in development of other motor skills. From this point of…

  14. Assessment of the Uniqueness of Wind Tunnel Strain-Gage Balance Load Predictions

    Science.gov (United States)

    Ulbrich, N.

    2016-01-01

    A new test was developed to assess the uniqueness of wind tunnel strain-gage balance load predictions that are obtained from regression models of calibration data. The test helps balance users to gain confidence in load predictions of non-traditional balance designs. It also makes it possible to better evaluate load predictions of traditional balances that are not used as originally intended. The test works for both the Iterative and Non-Iterative Methods that are used in the aerospace testing community for the prediction of balance loads. It is based on the hypothesis that the total number of independently applied balance load components must always match the total number of independently measured bridge outputs or bridge output combinations. This hypothesis is supported by a control volume analysis of the inputs and outputs of a strain-gage balance. It is concluded from the control volume analysis that the loads and bridge outputs of a balance calibration data set must separately be tested for linear independence because it cannot always be guaranteed that a linearly independent load component set will result in linearly independent bridge output measurements. Simple linear math models for the loads and bridge outputs in combination with the variance inflation factor are used to test for linear independence. A highly unique and reversible mapping between the applied load component set and the measured bridge output set is guaranteed to exist if the maximum variance inflation factor of both sets is less than the literature recommended threshold of five. Data from the calibration of a six{component force balance is used to illustrate the application of the new test to real-world data.

  15. Dynamic queuing transmission model for dynamic network loading

    DEFF Research Database (Denmark)

    Raovic, Nevena; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2017-01-01

    This paper presents a new macroscopic multi-class dynamic network loading model called Dynamic Queuing Transmission Model (DQTM). The model utilizes ‘good’ properties of the Dynamic Queuing Model (DQM) and the Link Transmission Model (LTM) by offering a DQM consistent with the kinematic wave theory...... and allowing for the representation of multiple vehicle classes, queue spillbacks and shock waves. The model assumes that a link is split into a moving part plus a queuing part, and p that traffic dynamics are given by a triangular fundamental diagram. A case-study is investigated and the DQTM is compared...

  16. A Discussion of Spatial Load Balancing Algorithms%空间负载平衡探讨

    Institute of Scientific and Technical Information of China (English)

    赵晓晖; 方裕; 赵家敏; 马艳

    2011-01-01

    Spatial load balancing is the important resource management module in distributed GIS, which can make the system better availability, reliability and high performance. To design and use spatial load balancing algorithms is a key research direction of the current distributed GIS. First,this paper introduces the definition and classification of spatial load balancing,and gives the six elements of a spatial load balancing algorithm. Secondly,the paper discusses three kinds of spatial load balancing algorithms:the basic spatial load balancing algorithms,the spatial load balancing algorithms based on grid,and the spatial load balancing algorithms based on simulation.Thirdly, this paper compares and analyzes the advantages and disadvantages of each kind of spatial load balancing algorithms,and divides these researches into four groups: the classical spatial load balancing algorithms, the application of new information technologies, the integration between spatial lookup algorithms and the mechanism of spatial references, and the combination of simulation and geometry. In addition, the paper presents that these above algorithms are preliminary and they do not lucubrate or make in-depth analysis. And the paper gives examples of spatial data migration and spatial multi-layer application to show the importance of the study on spatial load balancing and the complication of implementing the spatial load balancing. In conclusion,the paper also points out the existing problem and discusses the direction of future research.%设计、应用合理的空间负载平衡算法是当前分布式地理信息系统研究的一个重要方向.该文介绍了空间负载平衡的基本概念,给出了空间负载平衡的基本算法和改进算法及其空间应用研究现状.对于各种算法进行对比讨论,分析其优劣,指出存在的问题和未来研究的方向.

  17. Nonlinear dynamical characteristics of bed load motion

    Institute of Scientific and Technical Information of China (English)

    BAI; Yuchuan; XU; Haijue; XU; Dong

    2006-01-01

    Bed forms of various kinds that evolve naturally on the bottom of sandy coasts and rivers are a result of the kinematics of bed load transport. Based on the group motion of particles in the bed load within the bottom layer, a study on the nonlinear dynamics of bed load transport is presented in this paper. It is found that some development stages, such as the initiation, the equilibrium sediment transport, and the transition from a smooth bed to sand dunes, can be accounted for by different states in the nonlinear system of the bed load transport. It is verified by comparison with experimental data reported by Laboratoire Nationae D'Hydraulique, Chatou, France, that the evolution from a smooth bed to sand dunes is determined by mutation in the bed load transport. This paper presents results that may offer theoretical explanations to the experimental observations. It is also an attempt to apply the state-of-the-art nonlinear science to the classical sediment transport mechanics.

  18. On dynamic loads in parallel shaft transmissions. 2: Parameter study

    Science.gov (United States)

    Lin, Edward Hsiang-Hsi; Huston, Ronald L.; Coy, John J.

    1987-01-01

    Solutions to the governing equations of a spur gear transmission model, developed in NASA TM-100180 (AVSCOM TM-87-C-2), are presented. Factors affecting the dynamic load are identified. It is found that the dynamic load increases with operating speed up to a system natural frequency. At operating speeds beyond the natural frequency the dynamic load decreases dramatically. Also. it is found that the applied load and shaft inertia have little effect on the dynamic load. Damping and friction decrease the dynamic load. Finally, tooth stiffness has a significant effect on dynamic loading; the higher the stiffness, the lower the dynamic loading. Also, the higher the stiffness the higher the rotating speed required for dynamic response.

  19. Assessment of New Load Schedules for the Machine Calibration of a Force Balance

    Science.gov (United States)

    Ulbrich, N.; Gisler, R.; Kew, R.

    2015-01-01

    New load schedules for the machine calibration of a six-component force balance are currently being developed and evaluated at the NASA Ames Balance Calibration Laboratory. One of the proposed load schedules is discussed in the paper. It has a total of 2082 points that are distributed across 16 load series. Several criteria were applied to define the load schedule. It was decided, for example, to specify the calibration load set in force balance format as this approach greatly simplifies the definition of the lower and upper bounds of the load schedule. In addition, all loads are assumed to be applied in a calibration machine by using the one-factor-at-a-time approach. At first, all single-component loads are applied in six load series. Then, three two-component load series are applied. They consist of the load pairs (N1, N2), (S1, S2), and (RM, AF). Afterwards, four three-component load series are applied. They consist of the combinations (N1, N2, AF), (S1, S2, AF), (N1, N2, RM), and (S1, S2, RM). In the next step, one four-component load series is applied. It is the load combination (N1, N2, S1, S2). Finally, two five-component load series are applied. They are the load combination (N1, N2, S1, S2, AF) and (N1, N2, S1, S2, RM). The maximum difference between loads of two subsequent data points of the load schedule is limited to 33 % of capacity. This constraint helps avoid unwanted load "jumps" in the load schedule that can have a negative impact on the performance of a calibration machine. Only loadings of the single- and two-component load series are loaded to 100 % of capacity. This approach was selected because it keeps the total number of calibration points to a reasonable limit while still allowing for the application of some of the more complex load combinations. Data from two of NASA's force balances is used to illustrate important characteristics of the proposed 2082-point calibration load schedule.

  20. A Performance Comparison of Stability, Load-Balancing and Power-Aware Routing Protocols for Mobile Ad Hoc Networks

    Science.gov (United States)

    2010-06-01

    and on-demand protocols like the Dynamic Source Routing (DSR) [5], Ad hoc On-demand Distance Vector ( AODV ) routing [6], Location-aided Routing (LAR...minimum residual battery power of a node in the route . MMBCR can be implemented on the top of any on-demand routing protocol like DSR, AODV and etc...Comparison of Stability, Load-Balancing and Power-Aware Routing Protocols for Mobile Ad Hoc Networks Natarajan Meghanathan1 and Leslie C. Milton2

  1. Modelling and Analysis of a New Piezoelectric Dynamic Balance Regulator

    Directory of Open Access Journals (Sweden)

    Mu-Xun Xu

    2012-11-01

    Full Text Available In this paper, a new piezoelectric dynamic balance regulator, which can be used in motorised spindle systems, is presented. The dynamic balancing adjustment mechanism is driven by an in-plane bending vibration from an annular piezoelectric stator excited by a high-frequency sinusoidal input voltage. This device has different construction, characteristics and operating principles than a conventional balance regulator. In this work, a dynamic model of the regulator is first developed using a detailed analytical method. Thereafter, MATLAB is employed to numerically simulate the relations between the dominant parameters and the characteristics of the regulator based on thedynamic model. Finally, experimental measurements are used to certify the validity of the dynamic model. Consequently, the mathematical model presented and analysed in this paper can be used as a tool for optimising the design of a piezoelectric dynamic balance regulator during steady state operation.

  2. Valiant load-balanced robust routing under hose model for WDM mesh networks

    Science.gov (United States)

    Zhang, Xiaoning; Li, Lemin; Wang, Sheng

    2006-09-01

    In this paper, we propose Valiant Load-Balanced robust routing scheme for WDM mesh networks under the model of polyhedral uncertainty (i.e., hose model), and the proposed routing scheme is implemented with traffic grooming approach. Our Objective is to maximize the hose model throughput. A mathematic formulation of Valiant Load-Balanced robust routing is presented and three fast heuristic algorithms are also proposed. When implementing Valiant Load-Balanced robust routing scheme to WDM mesh networks, a novel traffic-grooming algorithm called MHF (minimizing hop first) is proposed. We compare the three heuristic algorithms with the VPN tree under the hose model. Finally we demonstrate in the simulation results that MHF with Valiant Load-Balanced robust routing scheme outperforms the traditional traffic-grooming algorithm in terms of the throughput for the uniform/non-uniform traffic matrix under the hose model.

  3. The pathogenesis of tendinopathy: balancing the response to loading

    DEFF Research Database (Denmark)

    Magnusson, S Peter; Jørgensen, Henning Langberg; Kjaer, Michael

    2010-01-01

    , such as tendinopathy, which is characterized by pain during activity, localized tenderness upon palpation, swelling and impaired performance. Tendon histological changes include reduced numbers and rounding of fibroblasts, increased content of proteoglycans, glycosaminoglycans and water, hypervascularization......, thus implying that one or more 'weak links' are present in the structure. Understanding how tendon tissue adapts to mechanical loading will help to unravel the pathogenesis of tendinopathy.......Tendons are designed to withstand considerable loads. Mechanical loading of tendon tissue results in upregulation of collagen expression and increased synthesis of collagen protein, the extent of which is probably regulated by the strain experienced by the resident fibroblasts (tenocytes...

  4. Dynamical Models Explaining Social Balance and Evolution of Cooperation

    CERN Document Server

    Traag, V A; De Leenheer, P

    2013-01-01

    In social networks with positive and negative links the dominant theory of explaining its structure is that of social balance. The theory states that a network is balanced if its triads are balanced. Such a balanced network can be split into (at most) two opposing factions with positive links within a faction and negative links between them. Although inherently dynamical, the theory has long remained static, with a focus on finding such partitions. Recently however, a dynamical model was introduced which was shown to converge to a socially balanced state for certain symmetric initial conditions. Here we show this does not hold for general (non-symmetric) initial conditions. We propose an alternative model and show that it does converge to a socially balanced state generically. Moreover, in a basic model of evolution of cooperation of indirect reciprocity, the alternative model has an evolutionary advantage compared to the earlier model. The principal difference between the two models can be understood in term...

  5. Internet流量与负载均衡的研究%Internet Load and Traffic Balancing

    Institute of Scientific and Technical Information of China (English)

    李文正; 郭巧; 郭为民

    2005-01-01

    Load and traffic balancing for the Internet are analyzed. An intelligent domain name system(DNS) policy for the control and management of content distribution networks (CDN) is presented. An CDNs network based Unitech IntelliDNS is built, and performance of the network in realizing traffic and load balancing is measured. It is proved that CDNs provide a valuable service and the methods are feasible.

  6. Document distribution algorithm for load balancing on an extensible Web server architecture

    OpenAIRE

    Ng, CP; Wang, CL

    2001-01-01

    Access latency and load balancing are the two main issues in the design of clustered Web server architecture for achieving high performance. We propose a novel document distribution algorithm for load balancing on a cluster of distributed Web servers. We group Web pages that are likely to be accessed during a request session into a migrating unit, which is used as the basic unit of document placement. A modified binning algorithm is developed to distribute the migrating units among the Web se...

  7. Dynamic ice loads on conical structures

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Two series of model tests were performed to observe the dynamic ice loads on conical structures.The variable testing parameters include the water line diameter of the model cone and ice parameters.During small water line diameter tests,two-time breaking is found to be the typical failure of ice on steep conical structure,and also be controlled by other factors,such as ice speed and the cone angle.During big water line diameter tests,the ice sheet failed nonsimultaneously around the cone.Several independe...

  8. DYNAMICAL BALANCE STUDY OF RING REDUCER

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The basic structure of epicyclical gear transmission with inner teeth of single-ring, double-ring, three-ring and four-ring reducer are analyzed. The force analysis model of ring reducer is built. Following this, it is concluded that the present ring reducers have the problem that the inertia force or the inertia moment is lopsided. On the base of analysis and calculation the balanced ring reducer which can realize the balance of inertia force and inertia moment is brought forward, and so is its concrete realizing step. The specimen of the balanced ring reducer is designed and manufactured; the experiment is carried out on the gear transmission test bench. Compared with other ring reducer of the same power, the balanced ring reducer has many advantages, such as low vibration noise, low cost and less production difficulty and less heat. It is the substitute of other ring reducer of the same kind. Therefore, it has important theoretic significance and highly practical engineering value.

  9. Loading dynamics of a sliding DNA clamp.

    KAUST Repository

    Cho, Won-Ki

    2014-05-22

    Sliding DNA clamps are loaded at a ss/dsDNA junction by a clamp loader that depends on ATP binding for clamp opening. Sequential ATP hydrolysis results in closure of the clamp so that it completely encircles and diffuses on dsDNA. We followed events during loading of an E. coli β clamp in real time by using single-molecule FRET (smFRET). Three successive FRET states were retained for 0.3 s, 0.7 s, and 9 min: Hydrolysis of the first ATP molecule by the γ clamp loader resulted in closure of the clamp in 0.3 s, and after 0.7 s in the closed conformation, the clamp was released to diffuse on the dsDNA for at least 9 min. An additional single-molecule polarization study revealed that the interfacial domain of the clamp rotated in plane by approximately 8° during clamp closure. The single-molecule polarization and FRET studies thus revealed the real-time dynamics of the ATP-hydrolysis-dependent 3D conformational change of the β clamp during loading at a ss/dsDNA junction.

  10. An Efficient Adaptive Load Balancing Algorithm for Cloud Computing Under Bursty Workloads

    Directory of Open Access Journals (Sweden)

    S. F. Issawi

    2015-06-01

    Full Text Available Cloud computing is a recent, emerging technology in the IT industry. It is an evolution of previous models such as grid computing. It enables a wide range of users to access a large sharing pool of resources over the internet. In such complex system, there is a tremendous need for an efficient load balancing scheme in order to satisfy peak user demands and provide high quality of services. One of the challenging problems that degrade the performance of a load balancing process is bursty workloads. Although there are a lot of researches proposing different load balancing algorithms, most of them neglect the problem of bursty workloads. Motivated by this problem, this paper proposes a new burstness-aware load balancing algorithm which can adapt to the variation in the request rate by adopting two load balancing algorithms: RR in burst and Random in non-burst state. Fuzzy logic is used in order to assign the received request to a balanced VM. The algorithm has been evaluated and compared with other algorithms using Cloud Analyst simulator. Results show that the proposed algorithm improves the average response time and average processing time in comparison with other algorithms.

  11. Exercise, muscle, and the applied load-bone strength balance.

    Science.gov (United States)

    Giangregorio, L; El-Kotob, R

    2017-01-01

    A fracture occurs when the applied load is greater than the bone can withstand. Clinical practice guidelines for the management of osteoporosis include recommendations for exercise; one of the few therapies where the proposed anti-fracture mechanisms that include effects on both bone strength and applied loads, where applied loads can come in the form of a fall, externally applied loads, body weight, or muscle forces. The aim of this review is to provide an overview of the clinical evidence pertaining to the potential efficacy of exercise for preventing fractures in older adults, including its direct effects on outcomes along the causal pathway to fractures (e.g., falls, posture, bone strength) and the indirect effects on muscle or the muscle-bone relationship. The evidence is examined as it pertains to application in clinical practice. Considerations for future research are discussed, such as the need for trials in individuals with low bone mass or students that evaluate whether changes in muscle mediate changes in bone. Future trials should also consider adequacy of calorie or protein intake, the confounding effect of exercise-induced weight loss, or the most appropriate therapeutic goal (e.g., strength, weight bearing, or hypertrophy) and outcome measures (e.g., fracture, disability, cost-effectiveness).

  12. A LIMITED RESOURCE VECTOR LOAD-BALANCING ALGORITHM FOR SOFTSWITCH-BASED HETEROGENEOUS CLUSTERED MEDIA SERVER

    Institute of Scientific and Technical Information of China (English)

    Wu Naixing; Liao Jianxin; Zhu Xiaomin

    2006-01-01

    Based on the system feature of softswitch-based heterogeneous clustered media server, this paper proposed a limited resource vector load-balancing algorithm. The purpose of the algorithm was to balance the load of clusters by utilizing all system resources effectively and to avoid violent shaking of the system performance. A lot of simulations on the Petri net model of load balance system are conducted and the algorithm is compared with some traditional algorithms on balancing ability for heterogeneity, system throughput, request response time and performance stability. The results of simulations show that the algorithm achieves system higher performance and it has excellent ability to deal with the heterogeneity of clustered media server.

  13. Load-Balance Policy in Two Level-Cluster File System

    Institute of Scientific and Technical Information of China (English)

    LIU Yuling; SONG Weiwei; MA Xiaoxue

    2006-01-01

    In this paper, we explored a load-balancing algorithm in a cluster file system contains two levels of metadata-server,primary-level server quickly distributestasks to second-level servers depending on the closest load-balancing information. At the same time, we explored a method which accurately reflect I/O traffic and storage of storage-node: computing the heat-value of file, according to which we realized a more logical storage allocation. According to the experiment result, we conclude that this new algorithm shortens the executing time of tasks and improves the system performance compared with other load algorithm.

  14. Hip joint contact loads in older adults during recovery from forward loss of balance by stepping.

    Science.gov (United States)

    Graham, David F; Modenese, Luca; Trewartha, Grant; Carty, Christopher P; Constantinou, Maria; Lloyd, David G; Barrett, Rod S

    2016-09-06

    Hip joint contact loads during activities of daily living are not generally considered high enough to cause acute bone or joint injury. However there is some evidence that hip joint loads may be higher in stumble recovery from loss of balance. A common laboratory method used to evaluate balance recovery performance involves suddenly releasing participants from various static forward lean magnitudes (perturbation intensities). Prior studies have shown that when released from the same perturbation intensity, some older adults are able to recover with a single step, whereas others require multiple steps. The main purpose of this study was to use a musculoskeletal model to determine the effect of three balance perturbation intensities and the use of single versus multiple recovery steps on hip joint contact loads during recovery from forward loss of balance in community dwelling older adults (n=76). We also evaluated the association of peak hip contact loads with perturbation intensity, step length and trunk flexion angle at foot contact at each participant׳s maximum recoverable lean angle (MRLA). Peak hip joint contact loads were computed using muscle force estimates obtained using Static Optimisation and increased as lean magnitude was increased and were on average 32% higher for Single Steppers compared to Multiple Steppers. At the MRLA, peak hip contact loads ranged from 4.3 to 12.7 body weights and multiple linear stepwise regression further revealed that initial lean angle, step length and trunk angle at foot contact together explained 27% of the total variance in hip joint contact load. Overall findings indicated that older adults experience peak hip joint contact loads during maximal balance recovery by stepping that in some cases exceeded loads reported to cause mechanical failure of cadaver femurs. While step length and trunk flexion angle are strong predictors of step recovery performance they are at best moderate predictors of peak hip joint loading.

  15. Relationship between Postural Sway and Dynamic Balance in Stroke Patients.

    Science.gov (United States)

    Cho, Kihun; Lee, Kyoungsuk; Lee, Byungjoon; Lee, Hwangjae; Lee, Wanhee

    2014-12-01

    [Purpose] The purpose of the current study was to investigate the relationship between postural sway and dynamic balance in post stroke patients. [Subjects] Thirty-one stroke patients (20 men and 11 women; age 64.25 years; stroke duration 12.70 months; MMSE-K score 26.35) participated in this study. [Methods] This study applied a cross-sectional design. A Good Balance system was used for measurement of the postural sway velocity (anteroposterior and mediolateral) and velocity moment of subjects under the eyes open and eyes closed conditions in a standing posture. The postural sway of subjects was measured under two surface conditions (stable and unstable surfaces). [Results] On the unstable surface (foam), no significant correlation was observed between postural sway and dynamic balance except for the berg balance scale (BBS) score and anteroposterior postural sway velocity under the eyes open condition, anteroposterior postural sway velocity under the eyes closed condition, and postural sway velocity moment. In addition, in the stable condition, no significant correlation was observed between postural sway and dynamic balance. [Conclusion] Our results indicate that a decrease in postural sway does not necessarily reflect improvement of dynamic balance ability. We believe that this finding may be useful in balance rehabilitation for prevention of falls after a stroke.

  16. A Reliable Semi-Distributed Load Balancing Architecture of Heterogeneous Wireless Networks

    CERN Document Server

    Alam, Md Golam Rabiul; Nower, Naushin; Khan, Mohammed Shafiul Alam

    2012-01-01

    Now a day's Heterogeneous wireless network is a promising field of research interest. Various challenges exist in this hybrid combination like load balancing, resource management and so on. In this paper we introduce a reliable load balancing architecture for heterogeneous wireless communications to ensure certain level of quality of service. To conquer the problem of centralized and distributed design, a semi distributed load balancing architecture for multiple access networks is introduced. In this grid based design multiple Load and Mobile Agent Management Units is incorporated. To prove the compactness of the design, integrated reliability, signalling overhead and total processing time is calculated. And finally simulation result shows that overall system performance is improved by enhancing reliability, reducing signalling overhead and processing time.

  17. Effects of feed loading on nitrogen balances and fish performance in replicated recirculating aquaculture systems

    DEFF Research Database (Denmark)

    Pedersen, Lars-Flemming; Suhr, Karin Isabel; Dalsgaard, Anne Johanne Tang

    2012-01-01

    /L at steady state, and the concentration of nitrogenous compounds and organic matter were all positively correlated to feed loading.The TAN loading to the RAS from the specific feed type was assessed in a separate mass-balance study and used as input in a descriptive mathematical model (AQUASIM® software......This study investigated the effects of applying four fixed feed loadings to three replicated recirculating aquaculture systems (RAS) on water quality changes, nitrogenous balances and growth performance of rainbow trout (Oncorhynchus mykiss).Feed loadings ranged from 1.6 to 6.3kgfeed/m3 make......) developed to simulate processes affecting N mass-balances in the RAS. Nitrification kinetic rate constants were applied to the biofilter, and fractions of nitrifiers in suspended solids in the water phase were estimated based on existing information from waste water treatment processes. Two model scenarios...

  18. NEW TYPE OF VIBRATION STRUCTURE OF VERTICAL DYNAMIC BALANCING MACHINE

    Institute of Scientific and Technical Information of China (English)

    Li Dinggen; Cao Jiguang; Chen Chuanyao; Wang Junwen

    2004-01-01

    A new type of vibration structure of vertical dynamic balancing machine is designed, which is based on the analysis for swing frame of a traditional vertical dynamic balancing machine. The static unbalance and couple unbalance can be separated effectively by using the new machine with the new swing frame. By building the dynamics model, the advantages of the new structure are discussed in detail. The modal and harmonic response are analyzed by using the ANSYS7.0. By comparing the finite element modal analysis with the experimental modal analysis, the natural frequencies and vibration modes are found out. There are many spring boards in the new swing frame. Their stiffness is different and assort with each other. Furthermore, there are three sensors on the measurement points. Therefore, the new dynamic balancing machine can measure the static unbalance and couple unbalance directly, and the influence between them is faint. The new structure has the function of belt-strain compensation to improve the measurement precision. The practical result indicates that the new vertical dynamic balancing machine is suitable for inertial measurement of flying objects, and can overcome the shortcomings of traditional double-plane vertical dynamic balancing machines. The vertical dynamic balancing machine with the new vibration structure can be widely used in the future applications. The modeling and analysis of the new vibration structure provide theoretic instruction and practical experience for designing new type of vertical dynamic balancing machines. Based on the design principles such as stiffness-matching, frequency-adjacence and strain-compensation and so on, various new type of vibration structures can be designed.

  19. Static and dynamic balance deficiencies in chronic low back pain.

    Science.gov (United States)

    Tsigkanos, Christos; Gaskell, Lynne; Smirniotou, Athanasia; Tsigkanos, Georgios

    2016-11-21

    According to previously conducted studies, people with Low Back Pain (LBP) present with static balance deficiencies. The aim of the present study was to compare static, as well as dynamic balance ability between Chronic Low Back Pain (CLBP) and healthy subjects. The CLBP group comprised 17 subjects and the control group of 16 subjects, matched for age, BMI and gender. The protocol applied compared the balance ability when performing the Star Excursion Balance Test (SEBT) and the static 1-leg stance position. The innovation introduced in the protocol was that the participants performed not only the static 1-leg stance, but also the dynamic SEBT on a force plate which recorded the target sway (TS), i.e. the Center of Pressure (CoP) excursion. The CLBP group had significantly reduced performance in SEBT, coupled with greater static and dynamic TS values. Age and especially BMI also bear a significant effect on SEBT execution. The inclusion of SEBT and TS derived scores in a stepwise logistic regression equation lead to the correct classification of 85% of the subjects. Dynamic and static balance ability provide supplementary information for the identification of the presence of CLBP, with dynamic balance being more instrumental.

  20. Dynamic balancing with rotating radial electromagnetic force

    Institute of Scientific and Technical Information of China (English)

    李勇; 陆永平

    2004-01-01

    A method of producing rotating radial electromagnetic force with a separable structure is proposed,and an experimental model was designed on which open loop vibration control experiments were carried out. Experimental results prove that the electromagnetic force designed has a constant magnitude and an uniform speed,and the idea of using an electromagnetic force as an active control in automatic balancing is correct in principle,and practicable in engineering.

  1. User Association for Load Balancing in Heterogeneous Cellular Networks

    CERN Document Server

    Ye, Qiaoyang; Chen, Yudong; Al-Shalash, Mazin; Caramanis, Constantine; Andrews, Jeffrey G

    2012-01-01

    For small cell technology to significantly increase the capacity of tower-based cellular networks, mobile users will need to be actively pushed onto the more lightly loaded tiers (corresponding to, e.g., pico and femtocells), even if they offer a lower instantaneous SINR than the macrocell base station (BS). Optimizing a function of the long-term rates for each user requires (in general) a massive utility maximization problem over all the SINRs and BS loads. On the other hand, an actual implementation will likely resort to a simple biasing approach where a BS in tier j is treated as having its SINR multiplied by a factor A_j>=1, which makes it appear more attractive than the heavily-loaded macrocell. This paper bridges the gap between these approaches through several physical relaxations of the network-wide optimal association problem, whose solution is NP hard. We provide a low-complexity distributed algorithm that converges to a near-optimal solution with a theoretical performance guarantee, and we observe ...

  2. System Dynamics Modelling for a Balanced Scorecard

    DEFF Research Database (Denmark)

    Nielsen, Steen; Nielsen, Erland Hejn

    2008-01-01

    Purpose - To construct a dynamic model/framework inspired by a case study based on an international company. As described by the theory, one of the main difficulties of BSC is to foresee the time lag dimension of different types of indicators and their combined dynamic effects. Design/methodology...

  3. Load Balancing in a Networked Environment through Homogenization

    CERN Document Server

    Hossain, M Shahriar; Deb, Debzani; Khan, Kazi Muhammad Najmul Hasan; Joarder, Md Mahbubul Alam

    2011-01-01

    Distributed processing across a networked environment suffers from unpredictable behavior of speedup due to heterogeneous nature of the hardware and software in the remote machines. It is challenging to get a better performance from a distributed system by distributing task in an intelligent manner such that the heterogeneous nature of the system do not have any effect on the speedup ratio. This paper introduces homogenization, a technique that distributes and balances the workload in such a manner that the user gets the highest speedup possible from a distributed environment. Along with providing better performance, homogenization is totally transparent to the user and requires no interaction with the system.

  4. Biologically inspired load balancing mechanism in neocortical competitive learning

    Directory of Open Access Journals (Sweden)

    Amir eTal

    2014-03-01

    Full Text Available A unique delayed self-inhibitory pathway mediated by layer 5 Martinotti Cells was studied in a biologically inspired neural network simulation. Inclusion of this pathway along with layer 5 basket cell lateral inhibition caused balanced competitive learning, which led to the formation of neuronal clusters as were indeed reported in the same region. Martinotti pathway proves to act as a learning conscience, causing overly successful regions in the network to restrict themselves and let others fire. It thus spreads connectivity more evenly throughout the net and solves the dead unit problem of clustering algorithms in a local and biologically plausible manner

  5. Effects of Dynamic Neuromuscular Analysis Training on Static and Dynamic Balance in Indian Female Basketball Players

    Directory of Open Access Journals (Sweden)

    Archna Sharma

    2013-04-01

    Full Text Available The aim of this paper was to investigate the effects of dynamic neuromuscular analysis on static and dynamic balance of Indian state level female athletes. It was hypothesized that the training protocol would improve both static and dynamic components of the balance, improving dynamic balance more than static. A total of 43 randomly selected state level female basketball players aged 16 -18 years participated in the study. The subjects were further divided into two groups, viz. Dynamic Neuromuscular Analysis (DNA group (n=23 and control group (n = 20. Pre and post static balance was tested to all the subjects by Stork Balance Test (SBT and Balance Error Scoring System (BESS, and dynamic balance was measured by Star Excursion Balance Test (SEBT. DNA intervention of 90 minutes was given for 6 weeks while the control group followed traditional training. Results showed a significant improvement both in static and dynamic balance (p<0.001. It might be concluded that 6 week DNA training designed for the prevention of ACL injuries could also improve both static and dynamic balance in Indian female basketball players.

  6. Aggregated Residential Load Modeling Using Dynamic Bayesian Networks

    Energy Technology Data Exchange (ETDEWEB)

    Vlachopoulou, Maria; Chin, George; Fuller, Jason C.; Lu, Shuai

    2014-09-28

    Abstract—It is already obvious that the future power grid will have to address higher demand for power and energy, and to incorporate renewable resources of different energy generation patterns. Demand response (DR) schemes could successfully be used to manage and balance power supply and demand under operating conditions of the future power grid. To achieve that, more advanced tools for DR management of operations and planning are necessary that can estimate the available capacity from DR resources. In this research, a Dynamic Bayesian Network (DBN) is derived, trained, and tested that can model aggregated load of Heating, Ventilation, and Air Conditioning (HVAC) systems. DBNs can provide flexible and powerful tools for both operations and planing, due to their unique analytical capabilities. The DBN model accuracy and flexibility of use is demonstrated by testing the model under different operational scenarios.

  7. Co-operative Scheduled Energy Aware Load-Balancing technique for an Efficient Computational Cloud

    Directory of Open Access Journals (Sweden)

    T R V Anandharajan

    2011-03-01

    Full Text Available Cloud Computing in the recent years has been taking its evolution from the scientific to the non scientific and commercial applications. Power consumption and Load balancing are very important and complex problem in computational Cloud. A computational Cloud differs from traditional high-performance computing systems in the heterogeneity of the computing nodes, as well as the communication links that connect the different nodes together. Load Balancing is a very important component in the commodity services based cloud computing. There is a need to develop algorithms that can capture this complexity yet can be easily implemented and used to solve a wide range of load-balancing scenarios in a Data and Computing intensive applications. In this paper, we propose to find the best EFFICIENT cloud resource by Co-operative Power aware Scheduled Load Balancing solution to the Cloud load-balancing problem. The algorithm developed combines the inherent efficiency of the centralized approach, energy efficient and the fault-tolerant nature of the distributed environment like Cloud.

  8. Evaluation Of Scheduling And Load Balancing Techniques In Mobile Grid Architecture

    Directory of Open Access Journals (Sweden)

    Debabrata Singh

    2011-09-01

    Full Text Available Recent advances in mobile communications and computing are strong interest of the scientific community in the Grid have led to research into the Mobile Grid. Based on a realistic Mobile Grid architecture we formulate the problem of job scheduling and load balancing techniques in a mobile environment and performance metrics. We extended the work by introducing a new scheduling policy and load balancing policy based on the notion of installments and intra cluster load balancing algorithm and continue the evaluation of the expanded set of scheduling and load balancing strategies in an effort to overcome the intermittent character of connectivity in a mobile environment. On real wireless traces, we demonstrated the superiority of the proposed policy, and showed the feasibility of a Mobile Grid system and design the efficient scheduling and load balancing policies subject to the underlying mobility were based a small part of the offered resources is wasted and a small part of the workload has to be processed again .The size of the installments increases as the size of the aborted fragments of the workload increases.

  9. ELBA: A New Efficient Load-Balancing Association in IEEE 802.15.4-Based Wireless Sensor Networks

    Science.gov (United States)

    Lee, Jae-Hyung; Kim, Dong-Sung; Shin, Soo-Young

    In this letter, a novel association method called ELBA (efficient load balancing association) is proposed for improved load balancing in IEEE 802.15.4-based WSNs (wireless sensor networks). ELBA adds new nodes to the network in an efficient load-balancing manner by exploiting not only RSSI (received signal strength indicator), which is used in the standard, but also traffic-load, the number of allocated GTSs (guaranteed time slots), and the number of parent nodes and child nodes. Simulation results show that ELBA offers better performance in load balancing and preventing congestion.

  10. A unified algorithm for mobility load balancing in 3GPP LTE multi-cell networks

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; LIU Nan; LI ZhiHang; WU Ping; PAN ZhiWen; YOU XiaoHu

    2013-01-01

    3GPP long term evolution (LTE) is a promising candidate for the next-generation wireless network, which is expected to achieve high spectrum efficiency by using advanced physical layer techniques and flat network structures. However, the LTE network still faces the problem of load imbalance as in GSM/WCDMA networks, and this may cause significant deterioration of system performance. To deal with this problem, mobility load balancing (MLB) has been proposed as an important use case in 3GPP self-organizing network (SON), in which the serving cell of a user can be selected to achieve load balancing rather than act as the cell with the maximum received power. Furthermore, the LTE network aims to serve users with different quality-of-service (QoS) requirements, and the network-wide objective function for load balancing is distinct for different kinds of users. Thus, in this paper, a unified algorithm is proposed for MLB in the LTE network. The load balancing problem is first formulated as an optimization problem with the optimizing variables being cell-user connections. Then the complexity and overhead of the optimal solution is analyzed and a practical and distributed algorithm is given. After that, the proposed algorithm is evaluated for users with different kinds of QoS requirements, i.e., guaranteed bit rate (GBR) users with the objective function of load balance index and non-GBR (nGBR) users with the objective function of total utility, respectively. Simulation results show that the proposed algorithm leads to significantly balanced load distribution for GBR users to decrease the new call blocking rate, and for nGBR users to improve the cell-edge throughput at the cost of only slight deterioration of total throughput.

  11. E2AODV Protocol for Load Balancing in Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    R. S.D. Wahida Banu

    2012-01-01

    Full Text Available Problem statement: In mobile ad hoc networks there are a number of challenges in providing quality of service routing with energy efficiency and load balancing. Most routing protocols do not consider the problem of load balance. A routing protocol called energy Efficient Ad-hoc on Demand Vector (E2AODV is proposed. It addresses the quality of service issues such as throughput, end to end delay, load distribution and energy. Approach: This study presents a scheme to balance the load with energy efficiency considering both congestion and the nodes energy usage. A threshold value was used to judge if intermediate node was overloaded, variable and changing along with nodes interface queue length around the backward path. Results: The routing protocol called energy Efficient Ad hoc on Demand Vector (E2AODV that is intended to provide a reliable transmission with low energy consumption was compared with Ad-hoc on Demand Vector (AODV in terms of the packet delivery ratio, average end to end delay, load distribution and node energy consumption. Conclusion/Recommendation: E2AODV protocol chooses an optimum path with low energy usage. It provides a better scheme to balance the load with energy efficiency and packet delivery ratio. It can be further enhanced as a secure routing protocol for mobile ad-hoc networks.

  12. Dynamic Response of Axially Loaded Euler-Bernoulli Beams

    DEFF Research Database (Denmark)

    Bayat, M.; Barari, Amin; Shahidi, M.

    2011-01-01

    The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical...

  13. Dynamic workload balancing of parallel applications with user-level scheduling on the Grid

    CERN Document Server

    Korkhov, Vladimir V; Krzhizhanovskaya, Valeria V

    2009-01-01

    This paper suggests a hybrid resource management approach for efficient parallel distributed computing on the Grid. It operates on both application and system levels, combining user-level job scheduling with dynamic workload balancing algorithm that automatically adapts a parallel application to the heterogeneous resources, based on the actual resource parameters and estimated requirements of the application. The hybrid environment and the algorithm for automated load balancing are described, the influence of resource heterogeneity level is measured, and the speedup achieved with this technique is demonstrated for different types of applications and resources.

  14. On the dynamic effects during under-balanced drilling operations and their prevention

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.; Rommetveit, R.; Maglione, R.; Bijleveld, A.; Gazaniol, D.

    1997-12-31

    In most under-balanced drilling (UBD) operations, the under-balanced condition must be generated artificially by injecting gas into the well. Due to the high compressibility nature of the gaseous phase and interruptions to the system, the flowing system is a non-steady state one, especially when jointed pipes are used. This is experienced by the varying liquid and gas flow-out rates, and spikes in the bottom hole pressure. These dynamic pressures have been observed and documented in field UBD operations. This publication presents an extensive examination of the dynamic effects during an under-balanced operation, and it discusses measures that are necessary to avoid the excessive peak loading of the surface facilities, the excessive wellhead pressure, and accidental overbalanced situations downhole. 9 refs., 7 figs., 2 tabs.

  15. A Novel Approach of Load Balancing in Cloud Computing using Computational Intelligence

    Directory of Open Access Journals (Sweden)

    Shabnam Sharma

    2016-02-01

    Full Text Available Nature Inspired Meta-Heuristic algorithms are proved to be beneficial for solving real world combinatorial problems such as minimum spanning tree, knapsack problem, process planning problems, load balancing and many more. In this research work, existing meta-heuristic approaches are discussed. Due to astonishing feature of echolocation, bat algorithm has drawn major attention in recent years and is applicable in different applications such vehicle routing optimization, time-tabling in railway optimization problems, load balancing in cloud computing etc. Later, the biological behaviour of bats is explored and various areas of further research are discussed. Finally, the main objective of the research paper is to propose an algorithm for one of the most important application, which is load balancing in cloud computing environment.

  16. A Universal Tare Load Prediction Algorithm for Strain-Gage Balance Calibration Data Analysis

    Science.gov (United States)

    Ulbrich, N.

    2011-01-01

    An algorithm is discussed that may be used to estimate tare loads of wind tunnel strain-gage balance calibration data. The algorithm was originally developed by R. Galway of IAR/NRC Canada and has been described in the literature for the iterative analysis technique. Basic ideas of Galway's algorithm, however, are universally applicable and work for both the iterative and the non-iterative analysis technique. A recent modification of Galway's algorithm is presented that improves the convergence behavior of the tare load prediction process if it is used in combination with the non-iterative analysis technique. The modified algorithm allows an analyst to use an alternate method for the calculation of intermediate non-linear tare load estimates whenever Galway's original approach does not lead to a convergence of the tare load iterations. It is also shown in detail how Galway's algorithm may be applied to the non-iterative analysis technique. Hand load data from the calibration of a six-component force balance is used to illustrate the application of the original and modified tare load prediction method. During the analysis of the data both the iterative and the non-iterative analysis technique were applied. Overall, predicted tare loads for combinations of the two tare load prediction methods and the two balance data analysis techniques showed excellent agreement as long as the tare load iterations converged. The modified algorithm, however, appears to have an advantage over the original algorithm when absolute voltage measurements of gage outputs are processed using the non-iterative analysis technique. In these situations only the modified algorithm converged because it uses an exact solution of the intermediate non-linear tare load estimate for the tare load iteration.

  17. Dynamic buckling of stiffened plates subjected to explosion impact loads

    Science.gov (United States)

    Wang, J.; Guo, J.; Yao, X. L.; Zhang, A. M.

    2017-01-01

    The dynamic buckling characteristics and criteria of a ship's structural stiffened plate subjected to underwater explosion impact loads are investigated in this study. Using the structural deformations observed in the experiments of underwater explosions against a plated grillage model, the mode shapes of the dynamic buckling were obtained. Through the construction of a computational model of stiffened plates subjected to an underwater explosion shock wave, the impact load was theoretically calculated and transformed into a rectangular pulse. According to the different response patterns of stiffened plates under different impact loads, a dynamic buckling criterion for the stiffened plates subjected to an explosion shock wave was proposed. Additionally, the static buckling phenomenon in the stiffened plates was analysed based on the minimum excess principle. In combination with the dynamic buckling criterion, the effects of various stiffening configurations on the dynamic and static buckling loads are discussed. The calculation results show that when the equivalent rectangular pulse is 2-3 times that of the static buckling load, the responses of the stiffened plates under the original shock load and the equivalent rectangular pulse are virtually identical. The impact load amplitude is the primary influencing factor in the dynamic buckling of stiffened plates subjected to underwater explosive impact loads. The stiffened plate aspect ratio has a substantial influence on the dynamic load factor. The analytical method and results are presented, which can be used to design stiffened optimum hull structures to enhance the dynamic load carrying capacity to withstand underwater shock damage.

  18. Inverse Force Determination on a Small Scale Launch Vehicle Model Using a Dynamic Balance

    Science.gov (United States)

    Ngo, Christina L.; Powell, Jessica M.; Ross, James C.

    2017-01-01

    A launch vehicle can experience large unsteady aerodynamic forces in the transonic regime that, while usually only lasting for tens of seconds during launch, could be devastating if structural components and electronic hardware are not designed to account for them. These aerodynamic loads are difficult to experimentally measure and even harder to computationally estimate. The current method for estimating buffet loads is through the use of a few hundred unsteady pressure transducers and wind tunnel test. Even with a large number of point measurements, the computed integrated load is not an accurate enough representation of the total load caused by buffeting. This paper discusses an attempt at using a dynamic balance to experimentally determine buffet loads on a generic scale hammer head launch vehicle model tested at NASA Ames Research Center's 11' x 11' transonic wind tunnel. To use a dynamic balance, the structural characteristics of the model needed to be identified so that the natural modal response could be and removed from the aerodynamic forces. A finite element model was created on a simplified version of the model to evaluate the natural modes of the balance flexures, assist in model design, and to compare to experimental data. Several modal tests were conducted on the model in two different configurations to check for non-linearity, and to estimate the dynamic characteristics of the model. The experimental results were used in an inverse force determination technique with a psuedo inverse frequency response function. Due to the non linearity, the model not being axisymmetric, and inconsistent data between the two shake tests from different mounting configuration, it was difficult to create a frequency response matrix that satisfied all input and output conditions for wind tunnel configuration to accurately predict unsteady aerodynamic loads.

  19. Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics

    Directory of Open Access Journals (Sweden)

    Zhigang Shen

    2012-08-01

    Full Text Available The impacts of ventilation ratio and vent balance on cooling load and air flow of naturally ventilated attics are studied in this paper using an unsteady computational fluid dynamics (CFD model. Buoyancy-driven turbulent ventilations in attics of gable-roof residential buildings are simulated for typical summer conditions. Ventilation ratios from 1/400 to 1/25 combined with both balanced and unbalanced vent configurations are investigated. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively insensitive to the variations in ventilation ratio and vent configuration. The predicted temperature fields are characterized by thermal stratification, except for the soffit regions. It is demonstrated that an increase in ventilation ratio will reduce attic cooling load. Compared with unbalanced vent configurations, balanced attic ventilation is shown to be the optimal solution in both maximizing ventilating flow rate and minimizing cooling load for attics with ventilation ratio lower than 1/100. For attics with ventilation ratios greater than 1/67, a configuration of large ridge vent with small soffit vent favors ventilating air flow enhancement, while a configuration of small ridge vent with large soffit vent results in the lowest cooling energy consumption.

  20. New hose materials for dynamic loads

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, P.; Weber, J.; Wohlfarth, L. [Volkswagen AG, Wolfsburg (Germany)

    2001-07-01

    Dynamically stressed hoses continue to represent a challenge in the various areas where they are used in the automobile. This is true not only as regards the selection of suitable hose materials but also the necessary reinforcement technology. This is due to increasing requirements for temperature and chemical resistance resulting from new and further developments in the field of engines and assemblies. In addition to the 'classic' hose materials with internal and external elastomeric layers in conjunction with reinforcing elements (for example, servo hose or brake hose materials), the beginning of the 1990s saw increasing interest on the part of the automotive industry in hose and pipe materials made of thermoplastic elastomers (for example, TEEE) in the fields of intake and crankcase ventilation as well as plastic / rubber composite concepts for hoses. These plastic / rubber composite designs in particular are to be regarded as tailor-made problem solutions for specific functional and environmental aspects (minimisation of the permeation / emission of liquid or gaseous substances) in conjunction with a dynamic load-bearing capacity. (orig.)

  1. Plant water balance with tritiated water-tracing dynamical method

    Institute of Scientific and Technical Information of China (English)

    曾文炳; 颉红梅; 魏宝文; 陈荷生; 冯金朝; 董家伦

    1996-01-01

    The conception of "metabolic pool" is introduced and an ecosystem model consisting of sand body metabolic pool, plant metabolic pool, atmospheric pool and their corresponding channels is established. In addition, the input and output terms of water balance including plant transpiration etc. are measured by tritiated water-tracing dynamical method, etc. and thus a water balance table is obtained. Finally, the plant water balance in the steppified desert environment of the Shapotou area at southeastern fringe of Tengger Desert in China is comprehensively analysed.

  2. Dynamic loads in the glove machine due to the carriages reciprocating motion and the dynamic load reduction

    OpenAIRE

    2014-01-01

    This research is devoted to analyzing the dynamic loads generated in the glove machine at reciprocating motion of knitting and intermediate carriages. Proposed is a method for determining the maximum dynamic loads in the glove machine carriages’ drive. It is noted that the dynamic loads reduction can be achieved by equipping the drive with energy accumulation and compensation units, in which quality it is expedient to use the cylindrical compression springs. The obtained dependence allows to ...

  3. Implementation of GAMMON - An efficient load balancing strategy for a local computer system

    Science.gov (United States)

    Baumgartner, Katherine M.; Kling, Ralph M.; Wah, Benjamin W.

    1989-01-01

    GAMMON (Global Allocation from Maximum to Minimum in cONstant time), an efficient load-balancing algorithm, is described. GAMMON uses the available broadcast capability of multiaccess networks to implement an efficient search technique for finding hosts with maximal and minimal loads. The search technique has an average overhead which is independent of the number of participating stations. The transition from the theoretical concept to a practical, reliable, and efficient implementation is described.

  4. Load Balancing in WDM Optical Networks with and without Wavelength-Continuity Constraints

    Institute of Scientific and Technical Information of China (English)

    刘逢清; 曾庆济; 杨旭东; 朱栩; 肖石林

    2003-01-01

    In practical optical networks, there is often the same number of wavelengths in a fiber. But if it is notcarefully designed, there will be much difference in link load among different fibers, and unnecessary wavelengthswill be needed. This paper investigated this load balancing issues to minimize the wavelength requirements. BothInteger Linear Programming (ILP) and heuristic algorithms were presented to solve such a problem in WDM opti-cal networks with or without wavelength-continuity constraints.

  5. Dynamic loadings of deepwater spar palatform - A case study

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Narasimhan, M.C.; Ambulgekar, P.P.

    Various wave loadings are considered separately on the deepwater Spar platform, with the wave propagation along x-axis and dynamic analyses are carried out at 1150m water depth using Newmark- beta approach The dynamic responses along six degrees...

  6. Dynamic loads in the glove machine due to the carriages reciprocating motion and the dynamic load reduction

    Directory of Open Access Journals (Sweden)

    Vitaliy V. Chaban

    2014-12-01

    Full Text Available This research is devoted to analyzing the dynamic loads generated in the glove machine at reciprocating motion of knitting and intermediate carriages. Proposed is a method for determining the maximum dynamic loads in the glove machine carriages’ drive. It is noted that the dynamic loads reduction can be achieved by equipping the drive with energy accumulation and compensation units, in which quality it is expedient to use the cylindrical compression springs. The obtained dependence allows to determine the necessary stiffness of compression springs (energy accumulating and compensating units, at which the dynamic loads due to the carriages masses’ inertia can be almost completely eliminated.

  7. Utilizing hydropower for load balancing non-storable renewable energy sources - technical and environmental challenges

    Science.gov (United States)

    Alfredsen, K. T.; Killingtveit, A.

    2011-12-01

    lead to more dynamic water temperatures and alter the interaction with the adjacent hyporheic zone. Frequent drying and wetting may impact the aquatic ecosystem e.g. through stranding of fish, and it may increase erosion and sediment transport in receiving reservoirs and rivers. During winter, most Norwegian systems currently adapt releases to prevent unstable ice conditions and ice runs and a more intermittent production schedule may lead to more unstable ice conditions. More transient flow may also have implications in the transfer tunnels and new methods are needed to monitor conditions to avoid turbine damage and loss of production. As a part of the Norwegian governments focus on developing renewable energy, a number of research centers for environmentally friendly energy production were created in 2009. For one of these centers, Center for environmentally design of renewable energy (CEDREN), one of the main objectives is to study the use of the Norwegian hydropower system for large scale peaking and load balancing, and to provide means of mitigating possible unwanted impacts. We will present data on how increased load balancing will influence the Norwegian hydropower system and an overview of challenges and possible solutions that the new operational strategy may incur.

  8. Dynamic Response of Axially Loaded Euler-Bernoulli Beams

    DEFF Research Database (Denmark)

    Bayat, M.; Barari, Amin; Shahidi, M.

    2011-01-01

    expressions for geometrically nonlinear vibration of beams are provided. The effect of vibration amplitude on the nonlinear frequency is discussed. Comparison between Energy Balance Method results and those available in literature demonstrates the accuracy of this method. In Energy Balance Method contrary...... to the conventional methods, only one iteration leads to high accuracy of the solutions which are valid for a wide range of vibration amplitudes.......The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical...

  9. Design and Analysis of Adaptive Load Balancing Approach in Cloud Infrastructure

    Directory of Open Access Journals (Sweden)

    N.R. Ram Mohan

    2014-08-01

    Full Text Available In this study an Adaptive Load Balancing (ALB approach is developed to effectively balance the load distributed across the cloud servers to minimize bandwidth and energy consumption on service provisioning. Cloud computing infrastructure has evolved as highly scalable services with massive computation power and storage capability with the resources being provided as service by the cloud environment and guarantees the Service Level Agreement (SLA. However, the needs of the subscribers have grown to an extent that there requires a big active platform for load balancing even if the resources are shared. Besides, the cloud computing paradigm also needs to optimally balance the load at the middle of the servers in order to avoid hotspot and improve resource utility. To perform energy conservation in cloud infrastructures, the use of chronological traffic data from data centers uses a service request prediction model. Collaborative provable data possession scheme adopt Homomorphic verifiable responses and hash index hierarchy but the drawback is that the match index structure are not matched properly with clustering model. Different level of power tariffs and requests made to the servers affect the decisions, where to serve the cluster needs. SLA Laws on privacy includes a factor that decides whether the loads can be moved in or out of a cluster, whereas they affect the overall energy consumption. ALB approach balances the load from every cluster group by minimizing the bandwidth and energy consumption. With repetitive query messaging, ALB collects the information about the current load of other group and then computes the average energy and bandwidth consumption of each group. The ALB Approach not only balances the energy consumption but also enhances the utilization of resources with minimal bandwidth usage. Extensive level of experimental studies is conducted to illustrate the efficiency and effectiveness of the proposed method. An experimental

  10. Dynamic calibration and validation of an accelerometer force balance for hypersonic lifting models.

    Science.gov (United States)

    Singh, Prakash; Trivedi, Sharad; Menezes, Viren; Hosseini, Hamid

    2014-01-01

    An accelerometer-based force balance was designed and developed for the measurement of drag, lift, and rolling moment on a blunt-nosed, flapped delta wing in a short-duration hypersonic shock tunnel. Calibration and validation of the balance were carried out by a convolution technique using hammer pulse test and surface pressure measurements. In the hammer pulse test, a known impulse was applied to the model in the appropriate direction using an impulse hammer, and the corresponding output of the balance (acceleration) was recorded. Fast Fourier Transform (FFT) was operated on the output of the balance to generate a system response function, relating the signal output to the corresponding load input. Impulse response functions for three components of the balance, namely, axial, normal, and angular, were obtained for a range of input load. The angular system response function was corresponding to rolling of the model. The impulse response functions thus obtained, through dynamic calibration, were operated on the output (signals) of the balance under hypersonic aerodynamic loading conditions in the tunnel to get the time history of the unknown aerodynamic forces and moments acting on the model. Surface pressure measurements were carried out on the model using high frequency pressure transducers, and forces and moments were deduced thereon. Tests were carried out at model angles of incidence of 0, 5, 10, and 15 degrees. A good agreement was observed among the results of different experimental methods. The balance developed is a comprehensive force/moment measurement device that can be used on complex, lifting, aerodynamic geometries in ground-based hypersonic test facilities.

  11. Social Balance on Networks: The Dynamics of Friendship and Enmity

    CERN Document Server

    Antal, T; Redner, S

    2006-01-01

    How do social networks evolve when both friendly and unfriendly relations exist? Here we propose a simple dynamics for social networks in which the sense of a relationship can change so as to eliminate imbalanced triads--relationship triangles that contains 1 or 3 unfriendly links. In this dynamics, a friendly link changes to unfriendly or vice versa in an imbalanced triad to make the triad balanced. Such networks undergo a dynamic phase transition from a steady state to "utopia"--all friendly links--as the amount of network friendliness is changed. Basic features of the long-time dynamics and the phase transition are discussed.

  12. A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs

    Science.gov (United States)

    Sivakumar, B.; Bhalaji, N.; Sivakumar, D.

    2014-01-01

    In mobile ad hoc networks connectivity is always an issue of concern. Due to dynamism in the behavior of mobile nodes, efficiency shall be achieved only with the assumption of good network infrastructure. Presence of critical links results in deterioration which should be detected in advance to retain the prevailing communication setup. This paper discusses a short survey on the specialized algorithms and protocols related to energy efficient load balancing for critical link detection in the recent literature. This paper also suggests a machine learning based hybrid power-aware approach for handling critical nodes via load balancing. PMID:24790546

  13. A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs

    Directory of Open Access Journals (Sweden)

    B. Sivakumar

    2014-01-01

    Full Text Available In mobile ad hoc networks connectivity is always an issue of concern. Due to dynamism in the behavior of mobile nodes, efficiency shall be achieved only with the assumption of good network infrastructure. Presence of critical links results in deterioration which should be detected in advance to retain the prevailing communication setup. This paper discusses a short survey on the specialized algorithms and protocols related to energy efficient load balancing for critical link detection in the recent literature. This paper also suggests a machine learning based hybrid power-aware approach for handling critical nodes via load balancing.

  14. A survey on investigating the need for intelligent power-aware load balanced routing protocols for handling critical links in MANETs.

    Science.gov (United States)

    Sivakumar, B; Bhalaji, N; Sivakumar, D

    2014-01-01

    In mobile ad hoc networks connectivity is always an issue of concern. Due to dynamism in the behavior of mobile nodes, efficiency shall be achieved only with the assumption of good network infrastructure. Presence of critical links results in deterioration which should be detected in advance to retain the prevailing communication setup. This paper discusses a short survey on the specialized algorithms and protocols related to energy efficient load balancing for critical link detection in the recent literature. This paper also suggests a machine learning based hybrid power-aware approach for handling critical nodes via load balancing.

  15. Response of Rubble Foundation to Dynamic Loading

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Ibsen, Lars Bo

    1993-01-01

    The soil beneath vertical monolithic structures is subjected to a combination of static load due to the submerged weight of the structure and stochastic non-stationary loads as a result of the wave loads on the vertical wall. The stress conditions in the soil below a foundation exposed to both st...

  16. Response of Rubble Foundation to Dynamic Loading

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Ibsen, Lars Bo

    1994-01-01

    The soil beneath vertical monolithic structures is subjected to a combination of static load due to the submerged weight of the structure and stochastic non-stationary loads as a result of the wave loads on the vertical wall. The stress conditions in the soil below a foundation exposed to both st...

  17. Rethinking the neurological examination II: dynamic balance assessment

    Directory of Open Access Journals (Sweden)

    Péricles A. Maranhão-Filho

    2011-12-01

    Full Text Available The authors propose that the neurological exam needs reevaluation with respect to the dynamic balance test (walking. Validated tests such as: preferred and maximum gait speed, dynamic gait index, five-times-sit-to-stand test, timed up & go cognitive and manual, should be part of the neurological examination routine. In the neurological exam of older patients, these same bedside tests bring the plus of evaluation the risk of occasional falling.

  18. Dynamically-Loaded Hardware Libraries (HLL) Technology for Audio Applications

    DEFF Research Database (Denmark)

    Esposito, A.; Lomuscio, A.; Nunzio, L. Di

    2016-01-01

    In this work, we apply hardware acceleration to embedded systems running audio applications. We present a new framework, Dynamically-Loaded Hardware Libraries or HLL, to dynamically load hardware libraries on reconfigurable platforms (FPGAs). Provided a library of application-specific processors,...

  19. Dynamically-Loaded Hardware Libraries (HLL) Technology for Audio Applications

    DEFF Research Database (Denmark)

    Esposito, A.; Lomuscio, A.; Nunzio, L. Di

    2016-01-01

    In this work, we apply hardware acceleration to embedded systems running audio applications. We present a new framework, Dynamically-Loaded Hardware Libraries or HLL, to dynamically load hardware libraries on reconfigurable platforms (FPGAs). Provided a library of application-specific processors...

  20. A Location Selection Policy of Live Virtual Machine Migration for Power Saving and Load Balancing

    Directory of Open Access Journals (Sweden)

    Jia Zhao

    2013-01-01

    Full Text Available Green cloud data center has become a research hotspot of virtualized cloud computing architecture. And load balancing has also been one of the most important goals in cloud data centers. Since live virtual machine (VM migration technology is widely used and studied in cloud computing, we have focused on location selection (migration policy of live VM migration for power saving and load balancing. We propose a novel approach MOGA-LS, which is a heuristic and self-adaptive multiobjective optimization algorithm based on the improved genetic algorithm (GA. This paper has presented the specific design and implementation of MOGA-LS such as the design of the genetic operators, fitness values, and elitism. We have introduced the Pareto dominance theory and the simulated annealing (SA idea into MOGA-LS and have presented the specific process to get the final solution, and thus, the whole approach achieves a long-term efficient optimization for power saving and load balancing. The experimental results demonstrate that MOGA-LS evidently reduces the total incremental power consumption and better protects the performance of VM migration and achieves the balancing of system load compared with the existing research. It makes the result of live VM migration more high-effective and meaningful.

  1. Design and implementation of web server soft load balancing in small and medium-sized enterprise

    Science.gov (United States)

    Yan, Liu

    2011-12-01

    With the expansion of business scale, small and medium-sized enterprises began to use information platform to improve their management and competition ability, the server becomes the core factor which restricts the enterprise's infomationization construction. This paper puts forward a suitable design scheme for small and medium-sized enterprise web server soft load balancing, and proved it effective through experiment.

  2. A location selection policy of live virtual machine migration for power saving and load balancing.

    Science.gov (United States)

    Zhao, Jia; Ding, Yan; Xu, Gaochao; Hu, Liang; Dong, Yushuang; Fu, Xiaodong

    2013-01-01

    Green cloud data center has become a research hotspot of virtualized cloud computing architecture. And load balancing has also been one of the most important goals in cloud data centers. Since live virtual machine (VM) migration technology is widely used and studied in cloud computing, we have focused on location selection (migration policy) of live VM migration for power saving and load balancing. We propose a novel approach MOGA-LS, which is a heuristic and self-adaptive multiobjective optimization algorithm based on the improved genetic algorithm (GA). This paper has presented the specific design and implementation of MOGA-LS such as the design of the genetic operators, fitness values, and elitism. We have introduced the Pareto dominance theory and the simulated annealing (SA) idea into MOGA-LS and have presented the specific process to get the final solution, and thus, the whole approach achieves a long-term efficient optimization for power saving and load balancing. The experimental results demonstrate that MOGA-LS evidently reduces the total incremental power consumption and better protects the performance of VM migration and achieves the balancing of system load compared with the existing research. It makes the result of live VM migration more high-effective and meaningful.

  3. Uncertainty analysis on simple mass balance model to calculate critical loads for soil acidity

    Science.gov (United States)

    Harbin Li; Steven G. McNulty

    2007-01-01

    Simple mass balance equations (SMBE) of critical acid loads (CAL) in forest soil were developed to assess potential risks of air pollutants to ecosystems. However, to apply SMBE reliably at large scales, SMBE must be tested for adequacy and uncertainty. Our goal was to provide a detailed analysis of uncertainty in SMBE so that sound strategies for scaling up CAL...

  4. Public Infrastructure Investment, Output Dynamics, and Balanced Budget Fiscal Rules

    NARCIS (Netherlands)

    Duarte Bom, P.R.; Ligthart, J.E.

    2011-01-01

    We study the dynamic output and welfare effects of public infrastructure investment under a balanced budget fiscal rule, using an overlapping generations model of a small open economy. The government finances public investment by employing distortionary labor taxes. We find a negative short-run outp

  5. Public Infrastructure Investment, Output Dynamics, and Balanced Budget Fiscal Rules

    NARCIS (Netherlands)

    Duarte Bom, P.R.; Ligthart, J.E.

    2011-01-01

    We study the dynamic output and welfare effects of public infrastructure investment under a balanced budget fiscal rule, using an overlapping generations model of a small open economy. The government finances public investment by employing distortionary labor taxes. We find a negative short-run

  6. A Simple Method for Static Load Balancing of Parallel FDTD Codes

    DEFF Research Database (Denmark)

    Franek, Ondrej

    2016-01-01

    A static method for balancing computational loads in parallel implementations of the finite-difference timedomain method is presented. The procedure is fairly straightforward and computationally inexpensive, thus providing an attractive alternative to optimization techniques. The method is descri......A static method for balancing computational loads in parallel implementations of the finite-difference timedomain method is presented. The procedure is fairly straightforward and computationally inexpensive, thus providing an attractive alternative to optimization techniques. The method...... is described for partitioning in a single mesh dimension, but it is shown that it can be adapted also for 2D and 3D partitioning in approximate way, with good results. It is applicable to both homogeneous and heterogeneous parallel architectures, and can also be used for balancing memory on distributed memory...

  7. Profile modification to minimize spur gear dynamic loading

    Science.gov (United States)

    Lin, H. H.; Townsend, D. P.; Oswald, F. B.

    1989-01-01

    An analytical computer simulation program for dynamic modeling of low-contact-ratio spur gear systems is presented. The procedure computes the static transmission error of the gears operating under load and uses a fast Fourier transform to generate the frequency spectrum of the static transmission error at various tooth profile modifications. The dynamic loading response of an unmodified (perfect involute) gear pair was compared with that of gears with various profile modifications. Correlations were found between various profile modifications and the resulting dynamic loads. An effective error, obtained from frequency domain analysis of the static transmission error of the gears, gave a very good indication of the optimum profile modification to reduce gear dynamic loading. Design curves generated by dynamic simulation at various profile modifications are given for gear systems operated at various loads. Optimum profile modifications can be determined from these design curves for improved gear design.

  8. Optimal load balancing leveling method for multi-leg flexible platforms

    Science.gov (United States)

    Gang, Xianyue; Chai, Shan

    2013-09-01

    The working platforms supported with multiple extensible legs must be leveled before they come into operation. Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs, the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads. These problems make it quite complex and time consuming to level such a multi-leg platform. Based on rigid body kinematics, an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform, then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs. Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration, an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem. By taking advantage of the concept of supporting stiffness matrix, a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform. At the end, with the concept of supporting stiffness matrix and static transmissibility matrix, an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously. Three numerical examples are given out to illustrate the performance of proposed methods. This paper proposes a method which can effectively quantify all of the legs’ extension at the same time, achieve geometric leveling and legs’ loads balancing simultaneously. By using the proposed methods, the stability, precision and efficiency of auto-leveling control process can be improved.

  9. Dynamic balancing of mechanisms and synthesizing of parallel robots

    CERN Document Server

    Wei, Bin

    2016-01-01

    This book covers the state-of-the-art technologies in dynamic balancing of mechanisms with minimum increase of mass and inertia. The synthesis of parallel robots based on the Decomposition and Integration concept is also covered in detail. The latest advances are described, including different balancing principles, design of reactionless mechanisms with minimum increase of mass and inertia, and synthesizing parallel robots. This is an ideal book for mechanical engineering students and researchers who are interested in the dynamic balancing of mechanisms and synthesizing of parallel robots. This book also: ·       Broadens reader understanding of the synthesis of parallel robots based on the Decomposition and Integration concept ·       Reinforces basic principles with detailed coverage of different balancing principles, including input torque balancing mechanisms ·       Reviews exhaustively the key recent research into the design of reactionless mechanisms with minimum increase of mass a...

  10. Effect of Smart Phone Use on Dynamic Postural Balance

    OpenAIRE

    Cho, Sung-Hak; Choi, Mun-Hee; Goo, Bong-Oh

    2014-01-01

    [Purpose] The present study investigated what kind of effect smart phone use has on dynamic postural balance. [Subjects] The study subjects were 30 healthy students in their 20’s who were recruited from a University in Busan, Korea. [Methods] The present experiment was quasi-experimental research which measured the postural balance (Biodex) of subjects while they sent text messages via smart phones in the standing position with the eyes open, and while they used two-way SNS. [Results] There w...

  11. Relationship between Postural Sway and Dynamic Balance in Stroke Patients

    OpenAIRE

    2014-01-01

    [Purpose] The purpose of the current study was to investigate the relationship between postural sway and dynamic balance in post stroke patients. [Subjects] Thirty-one stroke patients (20 men and 11 women; age 64.25 years; stroke duration 12.70 months; MMSE-K score 26.35) participated in this study. [Methods] This study applied a cross-sectional design. A Good Balance system was used for measurement of the postural sway velocity (anteroposterior and mediolateral) and velocity moment of subjec...

  12. High-Resolution Force Balance Analyses of Tidewater Glacier Dynamics

    Science.gov (United States)

    Enderlin, E. M.; Hamilton, G. S.; O'Neel, S.

    2015-12-01

    Changes in glacier velocity, thickness, and terminus position have been used to infer the dynamic response of tidewater glaciers to environmental perturbations, yet few analyses have attempted to quantify the associated variations in the glacier force balance. Where repeat high-resolution ice thickness and velocity estimates are available, force balance time series can be constructed to investigate the redistribution of driving and resistive forces associated with changes in terminus position. Comparative force balance analyses may, therefore, help us understand the variable dynamic response observed for glaciers in close proximity to each other. Here we construct force balance time series for Helheim Glacier, SE Greenland, and Columbia Glacier, SE Alaska, to investigate differences in dynamic sensitivity to terminus position change. The analysis relies on in situ and remotely sensed observations of ice thickness, velocity, and terminus position. Ice thickness time series are obtained from stereo satellite image-derived surface elevation and continuity-derived bed elevations that are constrained by airborne radar observations. Surface velocity time series are obtained from interferometric synthetic aperture radar (InSAR) observations. Approximately daily terminus positions are from a combination of satellite images and terrestrial time-lapse photographs. Helheim and Columbia glaciers are two of the best-studied Arctic tidewater glaciers with comprehensive high-resolution observational time series, yet we find that bed elevation uncertainties and poorly-constrained stress-coupling length estimates still hinder the analysis of spatial and temporal force balance variations. Here we use a new observationally-based method to estimate the stress-coupling length which successfully reduces noise in the derived force balance but preserves spatial variations that can be over-smoothed when estimating the stress-coupling length as a scalar function of the ice thickness

  13. An Efficient Admission Control Algorithm for Load Balancing In Hierarchical Mobile IPv6 Networks

    CERN Document Server

    Harini, Prof P

    2009-01-01

    In hierarchical Mobile IPv6 networks, Mobility Anchor Point (MAP) may become a single point of bottleneck as it handles more and more mobile nodes (MNs). A number of schemes have been proposed to achieve load balancing among different MAPs. However, signaling reduction is still imperfect because these schemes also avoid the effect of the number of CNs. Also only the balancing of MN is performed, but not the balancing of the actual traffic load, since CN of each MN may be different. This paper proposes an efficient admission control algorithm along with a replacement mechanism for HMIPv6 networks. The admission control algorithm is based on the number of serving CNs and achieves actual load balancing among MAPs. Moreover, a replacement mechanism is introduced to decrease the new MN blocking probability and the handoff MN dropping probability. By simulation results, we show that, the handoff delay and packet loss are reduced in our scheme, when compared with the standard HMIPv6 based handoff.

  14. Detection and Use of Load and Gage Output Repeats of Wind Tunnel Strain-Gage Balance Data

    Science.gov (United States)

    Ulbrich, N.

    2017-01-01

    Criteria are discussed that may be used for the detection of load and gage output repeats of wind tunnel strain-gage balance data. First, empirical thresholds are introduced that help determine if the loads or electrical outputs of a pair of balance calibration or check load data points match. A threshold of 0.01 percent of the load capacity is suggested for the identification of matching loads. Similarly, a threshold of 0.1 microV/V is recommended for the identification of matching electrical outputs. Two examples for the use of load and output repeats are discussed to illustrate benefits of the implementation of a repeat point detection algorithm in a balance data analysis software package. The first example uses the suggested load threshold to identify repeat data points that may be used to compute pure errors of the balance loads. This type of analysis may reveal hidden data quality issues that could potentially be avoided by making calibration process improvements. The second example uses the electrical output threshold for the identification of balance fouling. Data from the calibration of a six-component force balance is used to illustrate the calculation of the pure error of the balance loads.

  15. Balancing Control Strategy for Li-Ion Batteries String Based on Dynamic Balanced Point

    Directory of Open Access Journals (Sweden)

    Dong-Hua Zhang

    2015-03-01

    Full Text Available The Li-ion battery is becoming the optimal choice for the Electric Vehicle’s (EV power supply. In order to protect the Li-ion battery from charging damage and to prolong the battery’s life, a special control strategy based on the dynamic balanced point along with a non-dissipative equalizer is presented. The main focus of the proposed control strategy is to insure that the individual cell of a battery pack will be rapidly, efficiently and simultaneously balanced, by adjusting equalizing current of each cell dynamically. In this paper, a model of a four series connected Li-ion batteries pack has been established to evaluate the proposed control strategy. Superior performance is demonstrated by the simulation and experiment.

  16. Node status algorithm for load balancing in distributed service architectures at paperless medical institutions.

    Science.gov (United States)

    Logeswaran, Rajasvaran; Chen, Li-Choo

    2008-12-01

    Service architectures are necessary for providing value-added services in telecommunications networks, including those in medical institutions. Separation of service logic and control from the actual call switching is the main idea of these service architectures, examples include Intelligent Network (IN), Telecommunications Information Network Architectures (TINA), and Open Service Access (OSA). In the Distributed Service Architectures (DSA), instances of the same object type can be placed on different physical nodes. Hence, the network performance can be enhanced by introducing load balancing algorithms to efficiently distribute the traffic between object instances, such that the overall throughput and network performance can be optimised. In this paper, we propose a new load balancing algorithm called "Node Status Algorithm" for DSA infrastructure applicable to electronic-based medical institutions. The simulation results illustrate that this proposed algorithm is able to outperform the benchmark load balancing algorithms-Random Algorithm and Shortest Queue Algorithm, especially under medium and heavily loaded network conditions, which are typical of the increasing bandwidth utilization and processing requirements at paperless hospitals and in the telemedicine environment.

  17. Pegasus:a distributed and load-balancing fingerprint identification system*#

    Institute of Scientific and Technical Information of China (English)

    Yun-xiang ZHAO; Wan-xin ZHANG; Dong-sheng LI‡; Zhen HUANG; Min-ne LI; Xi-cheng LU

    2016-01-01

    Fingerprint has been widely used in a variety of biometric identifi cation systems in the past several years due to its uniqueness and immutability. With the rapid development of fi ngerprint identifi cation techniques, many fi ngerprint identifi cation systems are in urgent need to deal with large-scale fi ngerprint storage and high concurrent recognition queries, which bring huge challenges to the system. In this circumstance, we design and implement a distributed and load-balancing fi ngerprint identifi cation system named Pegasus, which includes a distributed feature extraction subsystem and a distributed feature storage subsystem. The feature extraction procedure combines the Hadoop Image Processing Interface (HIPI) library to enhance its overall processing speed; the feature storage subsystem optimizes MongoDB’s default load balance strategy to improve the efficiency and robustness of Pegasus. Experiments and simulations are carried out, and results show that Pegasus can reduce the time cost by 70%during the feature extraction procedure. Pegasus also balances the difference of access load among front-end mongos nodes to less than 5%. Additionally, Pegasus reduces over 40%of data migration among back-end data shards to obtain a more reasonable data distribution based on the operation load (insertion, deletion, update, and query) of each shard.

  18. The Pattern as a Reusable Component to Adaptive Framework for Load Balancing Mobile Agent in Internet Banking

    Directory of Open Access Journals (Sweden)

    A. Meiappane

    2012-03-01

    Full Text Available In recent years, the Software Architecture (SA of an Internet banking has become one of the most challengeable and risky fields of modern technology. The advent of the Internet has revolutionized the way banking is being done. In Internet banking, we analyzed some attributes such as usage, security, availability, load balancing and so on. Among those attributes Load Balancing is a serious problem in the Internet and it is necessary to build new systems incorporating load balancing as integral part of their design. The use of patterns, which is of a reusable component, is a good tool to help designers build load balancing systems. In this paper we are going to propose cluster load balancing technique by using mobile agent.

  19. Scoring dynamics across professional team sports: tempo, balance and predictability

    CERN Document Server

    Merritt, Sears

    2013-01-01

    Despite growing interest in quantifying and modeling the scoring dynamics within professional sports games, relative little is known about what patterns or principles, if any, cut across different sports. Using a comprehensive data set of scoring events in nearly a dozen consecutive seasons of college and professional (American) football, professional hockey, and professional basketball, we identify several common patterns in scoring dynamics. Across these sports, scoring tempo---when scoring events occur---closely follows a common Poisson process, with a sport-specific rate. Similarly, scoring balance---how often a team wins an event---follows a common Bernoulli process, with a parameter that effectively varies with the size of the lead. Combining these processes within a generative model of gameplay, we find they both reproduce the observed dynamics in all four sports and accurately predict game outcomes. These results demonstrate common dynamical patterns underlying within-game scoring dynamics across prof...

  20. The load-balanced multi-dimensional bin-packing problem

    DEFF Research Database (Denmark)

    Trivella, Alessio; Pisinger, David

    2016-01-01

    that the average center of mass of the loaded bins falls as close as possible to an ideal point, for instance, the center of the bin. We formally describe the problem using mixed-integer linear programming models, from the simple case where we want to optimally balance a set of items already assigned to a single...... bin, to the general balanced bin-packing problem. Given the difficulty for standard solvers to deal even with small size instances, a multi-level local search heuristic is presented. The algorithm takes advantage of the Fekete-Schepers representation of feasible packings in terms of particular classes...

  1. Load-balanced broadcast routing in wireless Ad-hoc networks

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In wireless Ad-hoc networks, where mobile hosts are powered by batteries, the entire network may be partitioned because of the drainage of a small set of batteries.Therefore, the crucial issue is to improve the energy efficiency, with an objective of balancing energy consumption.A greedy algorithm called weighted minimum spanning tree (WMST) has been proposed, in which time complexity is O(n2).This algorithm takes into account the initial energy of each node and energy consumption of each communication.Simulation has demonstrated that the performance of the proposed algorithm improves the load balance and prolongs the lifetime.

  2. Centrifugal experimental study of suction bucket foundations under dynamic loading

    Science.gov (United States)

    Lu, Xiaobing; Wu, Yongren; Jiao, Bintian; Wang, Shuyun

    2007-12-01

    Centrifugal experiments were carried out to investigate the responses of suction bucket foundations under horizontal and vertical dynamic loading. It is shown that when the loading amplitude is over a critical value, the sand at the upper part around the bucket is softened or even liquefied. The excess pore pressure decreases from the upper part to the lower part of the sand layer in the vertical direction and decreases radially from the bucket’s side wall in the horizontal direction. Large settlements of the bucket and the sand layer around the bucket are induced by dynamic loading. The dynamic responses of the bucket with smaller height (the same diameter) are heavier.

  3. A Method for Balancing a Single-Phase Loaded Three-Phase Induction Generator

    Directory of Open Access Journals (Sweden)

    Yaw-Juen Wang

    2012-09-01

    Full Text Available When a three-phase induction generator (IG supplies unbalanced loads, its terminal voltages and line currents are also unbalanced, which may cause the IG to overheat and need to be derated. A single-phase loaded self-excited induction generator (SEIG works under most unfavorable load unbalance conditions. This paper proposes a three-capacitor circuit scheme and a method to find the values of the self-excitation capacitors that allow the SEIG to be balanced. The SEIG is modeled by a two-port network equivalent circuit that resolves the SEIG into its positive- and negative-sequence circuits associated with the self-excitation capacitors and the load. The network can then be analyzed by common AC circuit analysis techniques. Successful results for balancing the SEIG supplying a single-phase load have been achieved by properly choosing the values of the excitation capacitors. The proposed method has also been validated by experiments on a 0.37 kW SEIG.

  4. Multi-Layer Mobility Load Balancing in a Heterogeneous LTE Network

    DEFF Research Database (Denmark)

    Fotiadis, Panagiotis; Polignano, Michele; Laselva, Daniela;

    2012-01-01

    This paper analyzes the behavior of a distributed Mobility Load Balancing (MLB) scheme in a multi-layer 3GPP (3rd Generation Partnership Project) Long Term Evolution (LTE) deployment with different User Equipment (UE) densities in certain network areas covered with pico cells. Target of the study...... user performance. Results have shown that the proposed MLB scheme can significantly improve the overall network resources utilization by eliminating potential load imbalances amongst the deployment layers and consequently enhance user experience. However this occurs at the cost of increased Radio Link...

  5. 分布仿真系统二次调度负载均衡策略研究%Adaptive Policy of Dynamic Load Balancing of Parallel Server Cluster

    Institute of Scientific and Technical Information of China (English)

    沈萍萍; 陈珂; 张燕; 顾才东

    2011-01-01

    The research in order to solve the independent mobile robot navigation problem in which dynamic unknown, complex environment. Firstly, this paper develops a Fuzzy logic algorithm to solve the robot motion path problem by incorporating fuzzy logic control and priority-based behavior control. Four basic behaviors for mobile robot navigation are proposed, which is goal seeking, obstacle avoidance, tracking, and deadlock disarming, and which are realized through a fuzzy logic controller. Secondly, in particular for 'U' or 'V' shaped obstacles, where mobile robot may be trapped, a Path Remembering Behavior is prospered to protect robots from re-entering such areas through the Creation of Virtual Wall for not producing dead circulation. Finally, The Mat lab simulation results show that the proposed approach is effective in navigating mobile robots in a complex and unknown circumstance, and it has good robustness and adaptability to the unknown circumstance.%针对现有分布仿真系统负载纯静态、动态均衡典型策略无法同时兼顾并行效率最大性和通信开销最小性的缺陷,以机群在信息系统中的应用为背景提出了一种动静结合的二次调度负载均衡自适应策略.策略以提高系统响应速度为根本目标,包含信息搜集子策略、任务分配子策略和任务迁移子策略三个部分,由系统均衡服务器统一分配和仿真节点自主维护共同完成二次调度,能将任务均衡地分布到不同的节点上,寻求最大的并行性和最小通信开销的统一.通过仿真证明,随着节点服务器数目不断增多,采用动静结合的二次调度负载均衡自适应策略系统平均响应时间与纯静态或动态的负载均衡策略相比都有明显的改善.

  6. Peer-to-Peer Cloud Provisioning: Service Discovery and Load-Balancing

    CERN Document Server

    Ranjan, Rajiv; Wu, Xiaomin; Liu, Anna

    2009-01-01

    This chapter presents: (i) a layered peer-to-peer Cloud provisioning architecture; (ii) a summary of the current state-of-the-art in Cloud provisioning with particular emphasis on service discovery and load-balancing; (iii) a classification of the existing peer-to-peer network management model with focus on extending the DHTs for indexing and managing complex provisioning information; and (iv) the design and implementation of novel, extensible software fabric (Cloud peer) that combines public/private clouds, overlay networking and structured peer-to-peer indexing techniques for supporting scalable and self-managing service discovery and load-balancing in Cloud computing environments. Finally, an experimental evaluation is presented that demonstrates the feasibility of building next generation Cloud provisioning systems based on peer-to-peer network management and information dissemination models. The experimental test-bed has been deployed on a public cloud computing platform, Amazon EC2, which demonstrates t...

  7. An age-structured population balance model for microbial dynamics

    Directory of Open Access Journals (Sweden)

    Duarte M.V.E.

    2003-01-01

    Full Text Available This work presents an age-structured population balance model (ASPBM for a bioprocess in a continuous stirred-tank fermentor. It relates the macroscopic properties and dynamic behavior of biomass to the operational parameters and microscopic properties of cells. Population dynamics is governed by two time- and age-dependent density functions for living and dead cells, accounting for the influence of substrate and dissolved oxygen concentrations on cell division, aging and death processes. The ASPBM described biomass and substrate oscillations in aerobic continuous cultures as experimentally observed. It is noteworthy that a small data set consisting of nonsegregated measurements was sufficient to adjust a complex segregated mathematical model.

  8. Using preemptive thread migration to load-balance data-parallel applications

    OpenAIRE

    Antoniu, Gabriel; Pérez, Christian

    1999-01-01

    International audience; Generic load balancing policies for irregular parallel applications may be efficiently implemented by integrating preemptive thread migration into the runtime support. In this context, a delicate issue is to manage pointer validity in a migration-safe way. In [1] we presented an iso-address approach to this problem. This paper discusses the impact of the iso-address migration scheme on the runtime of the Adaptor [4] HPF compiler. This runtime (previously modified so as...

  9. Doubly Exponential Solution for Randomized Load Balancing Models with Markovian Arrival Processes and PH Service Times

    OpenAIRE

    Li,Quan-Lin; Lui, John C. S.

    2010-01-01

    In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solutions of randomized load balancing models (also known as supermarket models) with Markovian arrival processes (MAPs) and phase-type (PH) service times. We describe the supermarket model as a system of differential vector equations by means of density dependent jump Markov processes, and obtain a closed-form solution with a doubly exponential structure to the fixed point of the system of differential...

  10. Doubly Exponential Solution for Randomized Load Balancing Models with Markovian Arrival Processes and PH Service Times

    OpenAIRE

    Li, Quan-Lin; Lui, John C. S.

    2010-01-01

    In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solutions of randomized load balancing models (also known as supermarket models) with Markovian arrival processes (MAPs) and phase-type (PH) service times. We describe the supermarket model as a system of differential vector equations by means of density dependent jump Markov processes, and obtain a closed-form solution with a doubly exponential structure to the fixed point of the system of differential...

  11. Strain-balanced MQW pin solar cells grown using a robot-loading showerhead reactor

    Science.gov (United States)

    Roberts, J. S.; Airey, R.; Hill, G.; Calder, C.; Barnham, K. W. J.; Lynch, M.; Tibbits, T.; Johnson, D.; Pakes, A.; Grantham, T.

    2007-01-01

    A touch-screen controlled, robot-loading system for the Thomas Swan 7×2 flip-top showerhead reactor has been developed. The reactor has been configured for the growth of GaAs and InP materials and has been used to prepare strain-balanced MQW (SBMQW) pin solar cell material on GaAs substrates. Both material characterisation and solar cell performance for SBMQW pin cells are described.

  12. The stability and dynamic behaviour of fluid-loaded structures

    CSIR Research Space (South Africa)

    Suliman, Ridhwaan

    2015-07-01

    Full Text Available ECCOMAS Young Investigators Conference 6th GACM Colloquium, July 20–23, 2015, Aachen, Germany The stability and dynamic behaviour of fluid-loaded structures R. Suliman, N. Peake Abstract. The deformation of slender elastic structures due...

  13. Dynamical Model of Rocket Propellant Loading with Liquid Hydrogen

    Data.gov (United States)

    National Aeronautics and Space Administration — A dynamical model describing the multi-stage process of rocket propellant loading has been developed. It accounts for both the nominal and faulty regimes of...

  14. Characteristics of Nitrogen Balances of Large-scale Stock Farms and Reduction of Environmental Nitrogen Loads

    Science.gov (United States)

    Hattori, Toshihiro; Takamatsu, Rieko

    We calculated nitrogen balances on farm gate and soil surface on large-scale stock farms and discussed methods for reducing environmental nitrogen loads. Four different types of public stock farms (organic beef, calf supply and daily cows) were surveyed in Aomori Prefecture. (1) Farm gate and soil surface nitrogen inflows were both larger than the respective outflows on all types of farms. Farm gate nitrogen balance for beef farms were worse than that for dairy farms. (2) Soil surface nitrogen outflows and soil nitrogen retention were in proportion to soil surface nitrogen inflows. (3) Reductions in soil surface nitrogen retention were influenced by soil surface nitrogen inflows. (4) In order to reduce farm gate nitrogen retention, inflows of formula feed and chemical fertilizer need to be reduced. (5) In order to reduce soil surface nitrogen retention, inflows of fertilizer need to be reduced and nitrogen balance needs to be controlled.

  15. FPGA Acceleration by Dynamically-Loaded Hardware Libraries

    DEFF Research Database (Denmark)

    Lomuscio, Andrea; Nannarelli, Alberto; Re, Marco

    Hardware acceleration is a viable solution to obtain energy efficiency in data intensive computation. In this work, we present a hardware framework to dynamically load hardware libraries, HLL, on reconfigurable platforms (FPGAs). Provided a library of application-specific processors, we load on...

  16. Load Balancing Scheme on the Basis of Huffman Coding for P2P Information Retrieval

    Science.gov (United States)

    Kurasawa, Hisashi; Takasu, Atsuhiro; Adachi, Jun

    Although a distributed index on a distributed hash table (DHT) enables efficient document query processing in Peer-to-Peer information retrieval (P2P IR), the index costs a lot to construct and it tends to be an unfair management because of the unbalanced term frequency distribution. We devised a new distributed index, named Huffman-DHT, for P2P IR. The new index uses an algorithm similar to Huffman coding with a modification to the DHT structure based on the term distribution. In a Huffman-DHT, a frequent term is assigned to a short ID and allocated a large space in the node ID space in DHT. Throuth ID management, the Huffman-DHT balances the index registration accesses among peers and reduces load concentrations. Huffman-DHT is the first approach to adapt concepts of coding theory and term frequency distribution to load balancing. We evaluated this approach in experiments using a document collection and assessed its load balancing capabilities in P2P IR. The experimental results indicated that it is most effective when the P2P system consists of about 30, 000 nodes and contains many documents. Moreover, we proved that we can construct a Huffman-DHT easily by estimating the probability distribution of the term occurrence from a small number of sample documents.

  17. Cuckoo Genetic Optimization Algorithm for Efficient Job Scheduling with Load Balance in Grid Computing

    Directory of Open Access Journals (Sweden)

    Rachhpal Singh

    2016-08-01

    Full Text Available Grid computing incorporates dispersed resources to work out composite technical, industrial, and business troubles. Thus a capable scheduling method is necessary for obtaining the objectives of grid. The disputes of parallel computing are commencing with the computing resources for the number of jobs and intricacy, craving, resource malnourishment, load balancing and efficiency. The risk stumbling upon parallel computing is the enthusiasm to scrutinize different optimization techniques to achieve the tasks without unsafe surroundings. Here Cuckoo Genetic Optimization Algorithm (CGOA is established that was motivated from cuckoo optimization algorithm (COA and genetic algorithm (GA for task scheduling in parallel environment (grid computing system. This CGOA is implemented on parallel dealing out for effective scheduling of multiple tasks with less schedule length and load balance. Here transmission time is evaluated with number of job set. This is computed with the help of job-processor relationship. This technique handles the issues well and the results show that complexity, load balance and resource utilization are finely managed.

  18. Multi-Stage Admission Control for Load Balancing in Next Generation Systems

    DEFF Research Database (Denmark)

    Mihovska, Albena D.; Anggorojati, Bayu; Luo, Jijun;

    2008-01-01

    This paper describes a load-dependent multi-stage admission control suitable for next generation systems. The concept uses decision polling in entities located at different levels of the architecture hierarchy and based on the load to activate a sequence of actions related to the admission...... of a user to the network, i.e., the ranking of the intermediate decisions is dynamic. The decision is controlled by passing a token between the base station (BS) and the gateway (GW), thereby considering the load status of the BS and the backhaul network. A token is assigned to the entity with the highest...... load. Each admission request will issue a flag whose colour will reflect the load level in this entity and will determine the correct sequence of the required admission control actions....

  19. Stochastic dynamic programming for noise load management

    NARCIS (Netherlands)

    Meerburg, T.R.; van Kraaij, M.J.A.L.; Boucherie, Richardus J.; van Dijk, Nico

    2017-01-01

    Noise load reduction is among the primary performance targets for some airports. For airports with a complex lay-out of runways, runway selection may then be carried out via a preference list, an ordered set of runway combinations such that the higher on the list a runway combination, the better thi

  20. Fracture of Structural Materials under Dynamic Loading

    Science.gov (United States)

    1981-03-25

    Neverthe- less, the band provides a reliable ludication of the shape and average location of the Instability curve and thus allows discriminative...specimen before and after it was placed in the testing machine. The specimens were loaded in a hydraulically activated mechanical testing machine by the

  1. Load Balancing In Wireless Ad-Hoc Networks With Low Forwarding Index

    Directory of Open Access Journals (Sweden)

    Reena Dadhich

    2011-02-01

    Full Text Available A wireless ad-hoc network comprises of a set of wireless nodes and requires no fixed infrastructure. Forefficient communication between nodes, ad-hoc networks are typically grouped in to clusters, whereeach cluster has a clusterhead (or Master. In our study, we will take a communication model that isderived from that of BlueTooth. Clusterhead nodes are responsible for the formation of clusters eachconsisting of a number of nodes (analog to cells in a cellular network and maintenance of the topologyof the network. Consequently, the clusterhead tend to become potential points of failures and naturally,there will be load imbalanced. Thus, it is important to consider load balancing in any clusteringalgorithm. In this paper, we consider the situation when each node has some load, given by theparameter forwarding Index.

  2. Iterative load-balancing method with multigrid level relaxation for particle simulation with short-range interactions

    Science.gov (United States)

    Furuichi, Mikito; Nishiura, Daisuke

    2017-10-01

    We developed dynamic load-balancing algorithms for Particle Simulation Methods (PSM) involving short-range interactions, such as Smoothed Particle Hydrodynamics (SPH), Moving Particle Semi-implicit method (MPS), and Discrete Element method (DEM). These are needed to handle billions of particles modeled in large distributed-memory computer systems. Our method utilizes flexible orthogonal domain decomposition, allowing the sub-domain boundaries in the column to be different for each row. The imbalances in the execution time between parallel logical processes are treated as a nonlinear residual. Load-balancing is achieved by minimizing the residual within the framework of an iterative nonlinear solver, combined with a multigrid technique in the local smoother. Our iterative method is suitable for adjusting the sub-domain frequently by monitoring the performance of each computational process because it is computationally cheaper in terms of communication and memory costs than non-iterative methods. Numerical tests demonstrated the ability of our approach to handle workload imbalances arising from a non-uniform particle distribution, differences in particle types, or heterogeneous computer architecture which was difficult with previously proposed methods. We analyzed the parallel efficiency and scalability of our method using Earth simulator and K-computer supercomputer systems.

  3. Apparatus and method for optimal phase balancing using dynamic programming with spatial consideration

    Energy Technology Data Exchange (ETDEWEB)

    Robertazzi, Thomas G.; Skiena, Steven; Wang, Kai

    2017-08-08

    Provided are an apparatus and method for load-balancing of a three-phase electric power distribution system having a multi-phase feeder, including obtaining topology information of the feeder identifying supply points for customer loads and feeder sections between the supply points, obtaining customer information that includes peak customer load at each of the points between each of the feeder sections, performing a phase balancing analysis, and recommending phase assignment at the customer load supply points.

  4. Centrifugal experimental study of suction bucket foundations under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    Xiaobing Lu; Yongren Wu; Bintian Jiao; Shuyun Wang

    2007-01-01

    Centrifugal experiments were carded out to investigate the responses of suction bucket foundations under horizontal and vertical dynamic loading. It is shown that when the loading amplitude is over a critical value, the sand at the upper part around the bucket is softened or even liq-uefied. The excess pore pressure decreases from the upper part to the lower part of the sand layer in the vertical direc-tion and decreases radially from the bucket's side wall in the horizontal direction. Large settlements of the bucket and the sand layer around the bucket are induced by dynamic load-ing. The dynamic responses of the bucket with smaller height (the same diameter) are heavier.

  5. Dynamic Fracture Simulations of Explosively Loaded Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, Carly W. [Univ. of California, Davis, CA (United States). Dept. of Civil and Environmental Engineering; Goto, D. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-11-30

    This report documents the modeling results of high explosive experiments investigating dynamic fracture of steel (AerMet® 100 alloy) cylinders. The experiments were conducted at Lawrence Livermore National Laboratory (LLNL) during 2007 to 2008 [10]. A principal objective of this study was to gain an understanding of dynamic material failure through the analysis of hydrodynamic computer code simulations. Two-dimensional and three-dimensional computational cylinder models were analyzed using the ALE3D multi-physics computer code.

  6. Effect of smart phone use on dynamic postural balance.

    Science.gov (United States)

    Cho, Sung-Hak; Choi, Mun-Hee; Goo, Bong-Oh

    2014-07-01

    [Purpose] The present study investigated what kind of effect smart phone use has on dynamic postural balance. [Subjects] The study subjects were 30 healthy students in their 20's who were recruited from a University in Busan, Korea. [Methods] The present experiment was quasi-experimental research which measured the postural balance (Biodex) of subjects while they sent text messages via smart phones in the standing position with the eyes open, and while they used two-way SNS. [Results] There were significant differences between standing and the dual-task situations. Among dual tasks using smart phones, SNS using situations showed the highest instability. [Conclusion] The use of smart phones in less stable conditions such as while walking or in moving vehicles should be discouraged.

  7. Shaft centre orbit for dynamically loaded radial bearings

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2002-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 Booker1 and described further in 1972 Booker2. Several authors have refined...... seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work...

  8. Neuromuscular fatigue during dynamic maximal strength and hypertrophic resistance loadings.

    Science.gov (United States)

    Walker, Simon; Davis, Lisa; Avela, Janne; Häkkinen, Keijo

    2012-06-01

    The purpose of this study was to compare the acute neuromuscular fatigue during dynamic maximal strength and hypertrophic loadings, known to cause different adaptations underlying strength gain during training. Thirteen healthy, untrained males performed two leg press loadings, one week apart, consisting of 15 sets of 1 repetition maximum (MAX) and 5 sets of 10 repetition maximums (HYP). Concentric load and muscle activity, electromyography (EMG) amplitude and median frequency, was assessed throughout each set. Additionally, maximal bilateral isometric force and muscle activity was assessed pre-, mid-, and up to 30 min post-loading. Concentric load during MAX was decreased after set 10 (Pmuscle activity during HYP loading. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. DYNAMIC CHARACTERISTICS OF SOILS SUBJECT TO IMPACT LOADINGS

    Institute of Scientific and Technical Information of China (English)

    Zhirong Niu; Guoyun Lu; Dongzuo Cheng

    2008-01-01

    The dynamic properties of soil under impact loads are studied experimentally and numerically.By analyzing the microstructural photos of soils with and without impact,it is shown that impact loads can destroy the original structures in the compact area,where the soil grains are rearranged regularly and form the compact whirlpool structure.Simultaneously,the dynamic impact process of soil is simulated by using the software of Ls-dyna.The time-dependent distribution of the dynamic stress and density is obtained in the soil.Furthermore,the simulation results are consistent with the experimental results.The reinforcement mechanism and the rule of dynamic compaction of soils due to impact load are also elucidated.

  10. Dissipation and energy balance in electronic dynamics of Na clusters

    Science.gov (United States)

    Vincendon, Marc; Suraud, Eric; Reinhard, Paul-Gerhard

    2017-06-01

    We investigate the impact of dissipation on the energy balance in the electron dynamics of metal clusters excited by strong electro-magnetic pulses. The dynamics is described theoretically by Time-Dependent Density-Functional Theory (TDDFT) at the level of Local Density Approximation (LDA) augmented by a self interaction correction term and a quantum collision term in Relaxation-Time Approximation (RTA). We evaluate the separate contributions to the total excitation energy, namely energy exported by electron emission, potential energy due to changing charge state, intrinsic kinetic and potential energy, and collective flow energy. The balance of these energies is studied as function of the laser parameters (frequency, intensity, pulse length) and as function of system size and charge. We also look at collisions with a highly charged ion and here at the dependence on the impact parameter (close versus distant collisions). Dissipation turns out to be small where direct electron emission prevails namely for laser frequencies above any ionization threshold and for slow electron extraction in distant collisions. Dissipation is large for fast collisions and at low laser frequencies, particularly at resonances. Contribution to the Topical Issue "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

  11. Load balancing strategy of heterogeneous wireless networks based on multi-hop routing algorithm of ad hoc network

    Institute of Scientific and Technical Information of China (English)

    Pei Xuebing; Wang Qingping; Zhu Guangxi; Liu Gan

    2009-01-01

    Because of different system capacities of base station (BS) or access point (AP) and ununiformity of traffic distribution in different cells, quantities of new call users may be blocked in overloaded cell in communication hot spots. Whereas in some neighboring under-loaded cells, bandwidth may be superfluous because there are only few users to request services. In order to raise resource utilization of the whole heterogeneous networks, several novel load balancing strategies are proposed, which combine the call admission control policy and multi-hop routing protocol of ad-hoc network for load balancing. These load balancing strategies firstly make a decision whether to admit a new call or not by considering some parameters like load index and route cost, etc.., and then transfer the denied users into neighboring under-loaded cell with surplus channel according to optimum multi-hop routing algorithm. Simulation results show that the proposed load balancing strategies can distribute traffics to the whole heterogeneous wireless networks, improve the load balance index efficiently, and avoid the call block phenomenon almost absolutely.

  12. Performance Evaluation of Load Balancing in Hierarchical Architecture for Grid Computing Service Middleware

    Directory of Open Access Journals (Sweden)

    Abderezak Touzene

    2011-03-01

    Full Text Available In this paper, we propose a hierarchical architecture for grid computing service that allows grid users with limited resources to do any kind of computation using grid shared hardware and/or software resources. The term limited resources includes disk or diskless workstations, Palmtops or any mobile devices. The proposed grid computing service takes into account both hardware and software requirements of the user computing task. Our grid system needs to maximize the overall system throughput, minimize the user response time, and allows a good grid resources utilization. On this aspect, we propose an adaptive task allocation and load balancing algorithm to achieve the desired goals. We have developed a simulation model using network simulator NS2 to evaluate the performance of our grid system. We have also conducted some experiments on our test-bed prototype. The performance evaluation measures confirm the good quality (grid saturation level close to 90% of the grid load of our proposed architecture and load balancing algorithm.

  13. Immediate effects of ankle balance taping with kinesiology tape on the dynamic balance of young players with functional ankle instability.

    Science.gov (United States)

    Lee, Byeong-Gyu; Lee, Jung-Hoon

    2015-01-01

    Soccer, one of the most popular and well-known sports worldwide, involves complex motions such as running, quick changes in direction, jumping, and landing, all of which have a high risk of injury. Among them, ankle injuries are the most frequent. This study investigated the immediate effects of ankle balance taping (ABT) with kinesiology tape on the dynamic balance of young male soccer players with functional ankle instability (FAI). Nine young male soccer players with FAI in their dominant ankle were randomly subjected to no-, placebo-, and real-ABT conditions. After the appropriate treatment was administered, the dynamic balance was measured using the Star Excursion Balance Test (SEBT). In terms of the anterior and posterolateral reach distances on the SEBT, the real-ABT condition showed statistically significant increases compared to the no- and placebo-ABT conditions (p kinesiology tape can be expected to improve the dynamic balance of young male soccer players with FAI.

  14. Load balancing prediction method of cloud storage based on analytic hierarchy process and hybrid hierarchical genetic algorithm.

    Science.gov (United States)

    Zhou, Xiuze; Lin, Fan; Yang, Lvqing; Nie, Jing; Tan, Qian; Zeng, Wenhua; Zhang, Nian

    2016-01-01

    With the continuous expansion of the cloud computing platform scale and rapid growth of users and applications, how to efficiently use system resources to improve the overall performance of cloud computing has become a crucial issue. To address this issue, this paper proposes a method that uses an analytic hierarchy process group decision (AHPGD) to evaluate the load state of server nodes. Training was carried out by using a hybrid hierarchical genetic algorithm (HHGA) for optimizing a radial basis function neural network (RBFNN). The AHPGD makes the aggregative indicator of virtual machines in cloud, and become input parameters of predicted RBFNN. Also, this paper proposes a new dynamic load balancing scheduling algorithm combined with a weighted round-robin algorithm, which uses the predictive periodical load value of nodes based on AHPPGD and RBFNN optimized by HHGA, then calculates the corresponding weight values of nodes and makes constant updates. Meanwhile, it keeps the advantages and avoids the shortcomings of static weighted round-robin algorithm.

  15. Experimental study of aluminium honeycomb behaviour under dynamic multiaxial loading

    Directory of Open Access Journals (Sweden)

    Markiewicz E.

    2012-08-01

    Full Text Available Split Hopkinson Pressure Bar system (SHPB with large-diameter and Nylon bars introducing a shear-compression loading device is used in order to investigate the dynamic behaviour of aluminium honeycomb under multiaxial loadings conditions. All shear-compression configurations including the loading angle variation from 0∘ to 60∘ are performed with an impact velocity of about 15m/s. The adapted SHPB system with the device are validated numerically and a phenomenon of separation between the input bar and the input beveled bar is observed. Numerical results suggest that this phenomenon provides a cutting of the reflected wave. An electro optical extensometer is employed in experiments. A good agreement between the numerical elastic waves and the experimental ones is obtained. Experimental results show a significant effect of the loading angle on the apparent stress-strain curves. The initial peak value and the plateau stress decrease with the increase of the loading angle. The combined shear-compression device with an enhancement at the alignment set-up provides efficient results for samples dynamically loaded. This device will be used to investigate the influence of the in-plane orientation angle on the deformation mechanisms and multiaxial behaviour of aluminium honeycomb under dynamic and quasi-static loading conditions.

  16. Software-defined networking-based resource management: data offloading with load balancing in 5G HetNet

    National Research Council Canada - National Science Library

    Duan, Xiaoyu; Akhtar, Auon Muhammad; Wang, Xianbin

    2015-01-01

    ...) address network congestion by optimally balancing loads across multiple cells and iii) achieve the aforementioned objectives while taking network conditions and the end user quality-of-service (QoS...

  17. Using hob offset to balance dynamic strength in spur gears

    Science.gov (United States)

    Liou, Chuen-Huei; Lin, Hsi Hsiang; Oswald, Fred B.; Townsend, Dennis P.

    1995-05-01

    This paper presents an analytical study on the effect of hob offset on the dynamic tooth strength of spur gears. The study was limited to equal and opposite offset values applied to the pinion and gear to maintain the standard operating center distance. The analysis presented in this paper was performed using a new version of the NASA gear dynamics code DANST. The operating speed of the transmission has a significant influence on the amount of hob offset required to equalize the dynamic stresses in the pinion and gear. In the transmission studied, at low speeds, the optimum hob offset value was found to fluctuate. At higher speeds, the optimum value was constrained by the minimum allowed thickness at the tip of the pinion tooth. For gears that must operate over a range of speeds, an average offset value may be used. Spur gears designed with the procedure presented here can have significant improvements in load capacity.

  18. Dynamically loaded beam failure under corroded conditions

    NARCIS (Netherlands)

    Veerman, R.P.; Koenders, E.A.B.

    2014-01-01

    De-icing salts, used on roads in heavy winters, may enter reinforced concrete (RC) structures via its capillary pore system or via cracks, initiating reinforcement corrosion and reducing its remaining service-life. Vehicles passing real bridges exert a dynamic impact action that might activate a fat

  19. Dynamic Efficiency of a Container Crane’s Hoisting Transmission System under Hoisting Dynamic Load

    Directory of Open Access Journals (Sweden)

    Yuanyuan Liu

    2016-01-01

    Full Text Available The dynamic efficiency of hoisting transmission system on a container crane is fundamental for accurate efficiency prediction, while the dynamic efficiency of hoisting transmission system has not been investigated sufficiently. This paper will focus on dynamic efficiency of hoisting transmission system under hoisting dynamic load. A power loss model of gearbox was built. Then the dynamic model of gear transmission was developed including time-varying mesh stiffness and hoisting dynamic load was studied. Power loss, dynamic efficiency, and equivalent static efficiency were conducted in hoisting and lowering working conditions. The result shows that dynamic efficiency which consists of the significant lower frequency component coincided with hoisting load torque of the higher frequency component which is directly related to dynamic mesh and bearing force. And in two processes, the equivalent static efficiency in constant speed stage is min, whereas maximum value occurs in different stage. The research results lay a foundation for hoisting gear transmission dynamic efficiency analysis.

  20. IMPROVING RESOURCE UTILIZATION USING QoS BASED LOAD BALANCING ALGORITHM FOR MULTIPLE WORKFLOWS IN IAAS CLOUD COMPUTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    L. Shakkeera

    2013-06-01

    Full Text Available loud computing is the extension of parallel computing, distributed computing and grid computing. It provides secure, quick, convenient data storage and net computing services through the internet. The services are available to user in pay per-use-on-demand model. The main aim of using resources from cloud is to reduce the cost and to increase the performance in terms of request response time. Thus, optimizing the resource usage through efficient load balancing strategy is crucial. The main aim of this paper is to develop and implement an Optimized Load balancing algorithm in IaaS virtual cloud environment that aims to utilize the virtual cloud resources efficiently. It minimizes the cost of the applications by effectively using cloud resources and identifies the virtual cloud resources that must be suitable for all the applications. The web application is created with many modules. These modules are considered as tasks and these tasks are submitted to the load balancing server. The server which consists our load balancing policies redirect the tasks to the corresponding virtual machines created by KVM virtual machine manager as per the load balancing algorithm. If the size of the database inside the machine exceeds then the load balancing algorithm uses the other virtual machines for further incoming request. The load balancing strategy are evaluated for various QoS performance metrics like cost, average execution times, throughput, CPU usage, disk space, memory usage, network transmission and reception rate, resource utilization rate and scheduling success rate for the number of virtual machines and it improves the scalability among resources using load balancing techniques.

  1. Adaptive Distributed Load Balancing Routing Mechanism for LEO Satellite IP Networks

    Directory of Open Access Journals (Sweden)

    Xiao Ma

    2014-04-01

    Full Text Available LEO (Low Earth Orbit satellite constellation is an ideal scheme for the next generation wideband internet. The constellation is formed as a mesh-like network with inter satellite links (ISLs which are equipped between the neighbor satellites for transmitting directly. As to the future wideband IP services, an efficient routing mechanism will play an important role in improving the performance and balancing the network traffic. An Adaptive Distributed Load Balancing Routing Mechanism (ADLB is proposed in this paper to address the above-mentioned issues. This mechanism makes well-performed routing decision based on the current and historical status of each ISLs in each satellite node. With collecting historical information from network initiated, a proper mechanism is contained in ADLB for making required computing power and storage space in a reasonable range. The performance of ADLB is verified via a series of simulations which demonstrate that the scheme can provide better throughput and lower packet drop rate.

  2. A low overhead load balancing router for network-on-chip

    Science.gov (United States)

    Xiaofeng, Zhou; Lu, Liu; Zhangming, Zhu; Duan, Zhou

    2016-11-01

    The design of a router in a network-on-chip (NoC) system has an important impact on some performance criteria. In this paper, we propose a low overhead load balancing router (LOLBR) for 2D mesh NoC to enhance routing performance criteria with low hardware overhead. The proposed LOLBR employs a balance toggle identifier to control the initial routing direction of X or Y for flit injection. The simplified demultiplexers and multiplexers are used to handle output ports allocation and contention, which provide a guarantee of deadlock avoidance. Simulation results show that the proposed LOLBR yields an improvement of routing performance over the reported routing schemes in average packet latency by 26.5%. The layout area and power consumption of the network compared with the reported routing schemes are 15.3% and 11.6% less respectively. Project supported by the National Natural Science Foundation of China (Nos. 61474087, 61322405, 61376039).

  3. Parallelization Load Balance Strategy for a Global Grid-Point Model

    Institute of Scientific and Technical Information of China (English)

    WU Xiangjun; CHEN Dehui; SONG Junqiang; JIN Zhiyan; YANG Xuesheng; ZHANG Hongliang

    2010-01-01

    The Global/Regional Assimilation and PrEdiction System(GRAPES)is a new-generation operational numerical weather prediction(NWP)model developed by the China Meteorological Administration(CMA).It is a grid-point model with a code structure different from that of spectral models used in other operational NWP centers such as the European Centre for Medium-Range Weather Forecasts(ECMWF),National Centers for Environmental Prediction(NCEP),and Japan Meteorological Agency(JMA),especially in the context of parallel computing.In the GRAPES global model,a semi-implicit semi-Lagrangian scheme is used for the discretization over a sphere,which requires careful planning for the busy communications between the arrays of processors,because the Lagrangian differential scheme results in shortened trajectories interpolated between the grid points at the poles and in the associated adjacent areas.This means that the latitude-longitude partitioning is more complex for the polar processors.Therefore,a parallel strategy with efficient computation,balanced load,and synchronous communication shall be developed.In this paper,a message passing approach based on MPI(Message Passing Interface)group communication is proposed.Its key-point is to group the polar processors in row with matrix-topology during the processor partitioning.A load balance task distribution algorithm is also discussed.Test runs on the IBM-cluster 1600 at CMA show that the new algorithm is of desired scalability,and the readjusted load balance scheme can reduce the absolute wall clock time by 10% or more.The quasi-operational runs of the model demonstrate that the wall clock time secured by the strategy meets the real-time needs of NWP operations.

  4. Design of Hybrid Dynamic Balancer and Vibration Absorber

    Directory of Open Access Journals (Sweden)

    Y. R. Wang

    2014-01-01

    Full Text Available This study proposed a novel hybrid dynamic balancer and vibration absorber that is cheaper than active dampers and more effective than passive dampers. The proposed damping system does not need to be altered structurally to deal with different damping targets. Rather, the proposed vibration absorber is capable of self-adjustment to the optimal damping location in order to achieve balance and, thereby, optimize damping effects. The proposed device includes a groove under the damping target with inertial mass hung from a coil spring beneath. This allows the device to bounce vertically or rotate in order to reduce vibrations in the main body. The coil spring vibration absorber can also slide along the groove in order to adjust its location continuously until the vibrations in the system are minimized and the main body is balanced. Experiments verify the efficacy of the proposed device in improving damping performance beyond what has been achieved using conventional devices. We also provide an explanation of the theoretical underpinnings of the design as well as the implications of these findings with regard to future developments.

  5. Evaluation of flawed piping under dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, R.E. (Applied Science and Technology, Inc., Poway, CA (United States)); Quinones, D.F. (Cloud (Robert L.) and Associates, Inc., Berkeley, CA (United States)); Gilman, J.D. (Electric Power Research Inst., Palo Alto, CA (United States))

    1992-10-01

    This report describes analytical and interpretative research on results of large-scale dynamic tests of flawed pipe which were conducted for the International Piping Integrity Research Group (IPIRG). Here, the adequacy of dynamic analysis methods is examined, as well as margins against failure associated with flaw evaluation criteria. Experimental and analytical results are related to requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Codes. Code limits of operability bound all test results. Guidance is offered on selection of Z-factors'' for austenitic materials to retain code safety margins. In the IPIRG tests, efforts to produce a nearly instantaneous full severance pipe break were unsuccessful, indicating that this hypothetical basis for plant accident evaluations is conservative.

  6. Dynamic Load Model using PSO-Based Parameter Estimation

    Science.gov (United States)

    Taoka, Hisao; Matsuki, Junya; Tomoda, Michiya; Hayashi, Yasuhiro; Yamagishi, Yoshio; Kanao, Norikazu

    This paper presents a new method for estimating unknown parameters of dynamic load model as a parallel composite of a constant impedance load and an induction motor behind a series constant reactance. An adequate dynamic load model is essential for evaluating power system stability, and this model can represent the behavior of actual load by using appropriate parameters. However, the problem of this model is that a lot of parameters are necessary and it is not easy to estimate a lot of unknown parameters. We propose an estimating method based on Particle Swarm Optimization (PSO) which is a non-linear optimization method by using the data of voltage, active power and reactive power measured at voltage sag.

  7. Parallel 3-dim fast Fourier transforms with load balancing of the plane waves

    CERN Document Server

    Gao, Xingyu; Fang, Jun; Wang, Han

    2016-01-01

    The plane wave method is most widely used for solving the Kohn-Sham equations in first-principles materials science computations. In this procedure, the three-dimensional (3-dim) trial wave functions' fast Fourier transform (FFT) is a regular operation and one of the most demanding algorithms in terms of the scalability on a parallel machine. We propose a new partitioning algorithm for the 3-dim FFT grid to accomplish the trade-off between the communication overhead and load balancing of the plane waves. It is shown by qualitative analysis and numerical results that our approach could scale the plane wave first-principles calculations up to more nodes.

  8. Effect of contact ratio on spur gear dynamic load

    Science.gov (United States)

    Liou, Chuen-Huei; Lin, Hsiang Hsi; Oswald, Fred B.; Townsend, Dennis P.

    A computer simulation is presented which shows how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented was performed using the NASA gear dynamics code, DANST. In the analysis, the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds, a contact ratio close to 2.0 minimized dynamic load. For low contact ratio gears (contact ratio less than 2.0), increasing the contact ratio reduced the gear dynamic load. For high contact ratio gears (contact ratio = or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high contact ratio gears minimized dynamic load better than low contact ratio gears.

  9. New iterative load balancing scheme with multi-grid level relaxation technique toward a large scale geodynamical granular simulation

    Science.gov (United States)

    Furuichi, M.; Nishiura, D.

    2016-12-01

    The complex dynamics of granular system is an essential part of natural processes such as crystal rich magma flow, accretion prism formation or tsunami sedimentation. Numerical modeling with Discrete Element Method (DEM) is an effective approach for understanding granular dynamics especially when the contact between particles induces strongly non-linear rheology (e.g. DEM-CFD simulation for magma reservoir [Bergantz et.al., Nature geo, 2015, Furuichi and Nishiura, G-cubed, 2014]). In Moving Lagrangian particle methods like DEM, a large number of particles is required to obtain an accurate solution. Therefore, an efficient parallelization of the code is important to handle huge particles system on HPC. However, since particles move around during the simulation, the workload between the different MPI processes becomes imbalance when using static sub-domains. To overcome this limitation, we present a new dynamic load balancing algorithms applicable to particle simulation methods such as DEM and Smoothed Particle Hydrodynamics (SPH) [Furuichi and Nishiura submitted to Comput. Phys. Comm.]. Our method utilizes flexible orthogonal domain decomposition in which the domain is divided into columns, each of which independently defines rectangle sub-domains by rows. We regard the difference of the executed time between neighbor logical processes as the residual of nonlinear problem of the domain change. The load balancing is attained by minimizing the residual within the framework of the iterative non-linear solver combined with the multi-grid level technique for the local relaxation. Scalability tests attest that the algorithm demonstrates close-to-optimal strong and weak scalability on the K-computer and the Earth Simulator. This result holds for even as well as uneven particle distribution, including different types of particles and heterogeneous computer architecture. We performed a DEM simulation with over 2 billion particles for demonstrating the proposed scheme. The

  10. Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

    2016-06-24

    The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

  11. Dynamic Analysis of Structural Columns Subjected to Impulsive Loading

    Institute of Scientific and Technical Information of China (English)

    GONG Shunfeng; LU Yong; GAO Feng; JIN Weiliang

    2006-01-01

    For a building structure subjected to impulsive loading,particularly shock and impact loading,the response of the critical columns is crucial to the behaviour of the entire system during and after the blast loading phase.Therefore,an appropriate evaluation of the column response and damage under short-duration impulsive loading is important in a comprehensive assessment of the performance of a building system.This paper reports a dynamic analysis approach for the response of RC columns subjected to impulsive loading.Considering that the dynamic response of a column in a frame structure can also be affected by the floor movement which relates to the global vibration of the frame system,a generic column-mass model is used,in which a concentrated mass is attached to the column top to simulate the effect of a global vibration.To take into account the high shear effect under impulsive load,the model is formulated using Timoshenko beam theory,and three main nonlinear mechanisms are considered.Two typical scenarios,one under a direct air blast loading,and another under a blast-induced ground excitation,are analyzed and the primary response features are highlighted.

  12. Dynamical maps, quantum detailed balance, and the Petz recovery map

    Science.gov (United States)

    Alhambra, Álvaro M.; Woods, Mischa P.

    2017-08-01

    Markovian master equations (formally known as quantum dynamical semigroups) can be used to describe the evolution of a quantum state ρ when in contact with a memoryless thermal bath. This approach has had much success in describing the dynamics of real-life open quantum systems in the laboratory. Such dynamics increase the entropy of the state ρ and the bath until both systems reach thermal equilibrium, at which point entropy production stops. Our main result is to show that the entropy production at time t is bounded by the relative entropy between the original state and the state at time 2 t . The bound puts strong constraints on how quickly a state can thermalize, and we prove that the factor of 2 is tight. The proof makes use of a key physically relevant property of these dynamical semigroups, detailed balance, showing that this property is intimately connected with the field of recovery maps from quantum information theory. We envisage that the connections made here between the two fields will have further applications. We also use this connection to show that a similar relation can be derived when the fixed point is not thermal.

  13. Radiation sterilized bone response to dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Mardas, Marcin, E-mail: marcin.mardas@skpp.edu.pl [Department of Oncology, Poznan University of Medical Sciences, ul. Szamarzewskiego 82/84, 60-569 Poznan (Poland); Kubisz, Leszek [Department of Biophysics, Poznan University of Medical Sciences, ul. Fredry 10, 61-701 Poznan (Poland); Biskupski, Piotr; Mielcarek, Slawomir [Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznan (Poland); Stelmach-Mardas, Marta [Department of Bromatology, Poznan University of Medical Sciences, ul. Marcelinska 420, 60-354 Poznan (Poland); Kaluska, Iwona [Centre for Radiation Research and Technology, Institute of Nuclear Chemistry and Technology, ul. Dorodna 16, 03-195 Warsaw (Poland)

    2012-08-01

    Allogeneic bone grafts are used on a large scale in surgeries. To avoid the risk of infectious diseases, allografts should be radiation-sterilized. So far, no international consensus has been achieved regarding the optimal radiation dose. Many authors suggest that bone sterilization deteriorates bone mechanical properties. However, no data on the influence of ionizing radiation on bone dynamic mechanical properties are available. Bovine femurs from 2-year old animal were machine cut and irradiated with the doses 10, 15, 25, 35, 45 and 50 kGy. Dynamic mechanical analysis was performed at 1-10 Hz at the temperature range of 0-350 Degree-Sign C in 3-point bending configuration. No statistically significant differences in storage modulus were observed. However, there were significant decreased values of loss modulus between the samples irradiated with doses of 10 ({down_arrow}14.3%), 15, 45 and 50 kGy ({down_arrow}33.2%) and controls. It was stated that increased irradiation dose decreases the temperature where collagen denaturation process starts and increases the temperature where the collagen denaturation process finishes. It was shown that activation energy of denaturation process is significantly higher for the samples irradiated with the dose of 50 kGy (615 kJ/mol) in comparison with control samples and irradiation with other doses (100-135 kJ/mol). - Highlights: Black-Right-Pointing-Pointer We examine changes in the storage modulus and loss modulus of samples irradiated with doses of 10-50 kGy. Black-Right-Pointing-Pointer We examine changes in the denaturation temperature of samples irradiated with doses of 10-50 kGy. Black-Right-Pointing-Pointer We examine changes in the activation energy of denaturation process of samples irradiated with doses of 10-50 kGy.

  14. Real Time Efficient Scheduling Algorithm for Load Balancing in Fog Computing Environment

    Directory of Open Access Journals (Sweden)

    Manisha Verma

    2016-04-01

    Full Text Available Cloud computing is the new era technology, which is entirely dependent on the internet to maintain large applications, where data is shared over one platform to provide better services to clients belonging to a different organization. It ensures maximum utilization of computational resources by making availability of data, software and infrastructure with lower cost in a secure, reliable and flexible manner. Though cloud computing offers many advantages, but it suffers from certain limitation too, that during load balancing of data in cloud data centers the internet faces problems of network congestion, less bandwidth utilization, fault tolerance and security etc. To get rid out of this issue new computing model called Fog Computing is introduced which easily transfer sensitive data without delaying to distributed devices. Fog is similar to the cloud only difference lies in the fact that it is located more close to end users to process and give response to the client in less time. Secondly, it is beneficial to the real time streaming applications, sensor networks, Internet of things which need high speed and reliable internet connectivity. Our proposed architecture introduced a new scheduling policy for load balancing in Fog Computing environment, which complete real tasks within deadline, increase throughput and network utilization, maintaining data consistency with less complexity to meet the present day demand of end users

  15. Operational Strategy of CBPs for load balancing of Operators in Advanced Main Control Room

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seunghwan; Kim, Yochan; Jung, Wondea [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    With the using of a computer-based control room in an APR1400 (Advanced Pressurized Reactor-1400), the operators' behaviors in the main control room had changed. However, though the working environment of operators has been changed a great deal, digitalized interfaces can also change the cognitive tasks or activities of operators. First, a shift supervisor (SS) can confirm/check the conduction of the procedures and the execution of actions of board operators (BOs) while confirming directly the operation variables without relying on the BOs. Second, all operators added to their work the use of a new CBP and Soft Controls, increasing their procedural workload. New operational control strategies of CBPs are necessary for load balancing of operator's task load in APR1400. In this paper, we compared the workloads of operators in an APR1400 who work with two different usages of the CBP. They are SS oriented usage and SS-BO collaborative usage. In this research, we evaluated the workloads of operators in an advanced main control room by the COCOA method. Two types of CBP usages were defined and the effects of these usages on the workloads were investigated. The obtained results showed that the workloads between operators in a control room can be balanced according to the CBP usages by assigning control authority to the operators.

  16. A load balancing bufferless deflection router for network-on-chip

    Science.gov (United States)

    Xiaofeng, Zhou; Zhangming, Zhu; Duan, Zhou

    2016-07-01

    The bufferless router emerges as an interesting option for cost-efficient in network-on-chip (NoC) design. However, the bufferless router only works well under low network load because deflection more easily occurs as the injection rate increases. In this paper, we propose a load balancing bufferless deflection router (LBBDR) for NoC that relieves the effect of deflection in bufferless NoC. The proposed LBBDR employs a balance toggle identifier in the source router to control the initial routing direction of X or Y for a flit in the network. Based on this mechanism, the flit is routed according to XY or YX routing in the network afterward. When two or more flits contend the same one desired output port a priority policy called nearer-first is used to address output ports allocation contention. Simulation results show that the proposed LBBDR yields an improvement of routing performance over the reported bufferless routing in the flit deflection rate, average packet latency and throughput by up to 13%, 10% and 6% respectively. The layout area and power consumption compared with the reported schemes are 12% and 7% less respectively. Project supported by the National Natural Science Foundation of China (Nos. 61474087, 61322405, 61376039).

  17. Modeling and Algorithm for Multiple Spanning Tree Provisioning in Resilient and Load Balanced Ethernet Networks

    Directory of Open Access Journals (Sweden)

    Steven S. W. Lee

    2015-01-01

    Full Text Available We propose a multitree based fast failover scheme for Ethernet networks. In our system, only few spanning trees are used to carry working traffic in the normal state. As a failure happens, the nodes adjacent to the failure redirect traffic to the preplanned backup VLAN trees to realize fast failure recovery. In the proposed scheme, a new leaf constraint is enforced on the backup trees. It enables the network being able to provide 100% survivability against any single link and any single node failure. Besides fast failover, we also take load balancing into consideration. We model an Ethernet network as a twolayered graph and propose an Integer Linear Programming (ILP formulation for the problem. We further propose a heuristic algorithm to provide solutions to large networks. The simulation results show that the proposed scheme can achieve high survivability while maintaining load balancing at the same time. In addition, we have implemented the proposed scheme in an FPGA system. The experimental results show that it takes only few μsec to recover a network failure. This is far beyond the 50 msec requirement used in telecommunication networks for network protection.

  18. Effect of segmental, localized lower limb cooling on dynamic balance.

    Science.gov (United States)

    Montgomery, Roger E; Hartley, Geoffrey L; Tyler, Christopher J; Cheung, Stephen S

    2015-01-01

    This study aimed to determine the effect of cooling progressively greater portions of the lower extremities on dynamic balance and neuromuscular activation. Ten healthy males (22.8 ± 3.4 yr, 76.5 ± 9.1 kg) performed one room air temperature control (22.4°C ± 0.8°C) and three trials of cold water immersion at 12°C (lateral malleolus, ankle; lateral femoral epicondyle, knee; anterior superior iliac spine, hip) for 10 min before performing a unipedal balance test (Star Excursion Balance Test (SEBT)) with their dominant limb. Muscle activation of the vastus lateralis, biceps femoris, tibialis anterior, and lateral gastrocnemius was measured with surface EMG during the SEBT. Core temperature remained euthermic throughout all trials. Gastrocnemius temperature decreased from control (30.4°C ± 0.5°C) with knee (23.7°C ± 1.7°C) and hip immersion (22.4°C ± 1.0°C), whereas vastus lateralis temperature decreased from control (33.7°C ± 1.7°C) with hip immersion (27.3°C ± 2.0°C) (P Cold water immersion influenced mean anterior and posterior reach distance on the SEBT in a dose-dependent fashion. Compared with those in control, mean anterior and posterior SEBT reach distances were not decreased with ankle (-1.38% and -0.74%, respectively) and knee immersion (-2.48% and -2.74%), whereas hip immersion significantly reduced SEBT by 4.73% and 4.05% (P Muscle activation was largely unaffected as the lower extremities were cooled, with only the lateral gastrocnemius during the anterior SEBT approaching a decrease (P = 0.059). Cooling larger portions of the lower extremities progressively affect dynamic balance, and thermal protection strategies should focus on maintaining temperature in the large muscle mass of the thigh.

  19. A Universal Threshold for the Assessment of Load and Output Residuals of Strain-Gage Balance Data

    Science.gov (United States)

    Ulbrich, N.; Volden, T.

    2017-01-01

    A new universal residual threshold for the detection of load and gage output residual outliers of wind tunnel strain{gage balance data was developed. The threshold works with both the Iterative and Non{Iterative Methods that are used in the aerospace testing community to analyze and process balance data. It also supports all known load and gage output formats that are traditionally used to describe balance data. The threshold's definition is based on an empirical electrical constant. First, the constant is used to construct a threshold for the assessment of gage output residuals. Then, the related threshold for the assessment of load residuals is obtained by multiplying the empirical electrical constant with the sum of the absolute values of all first partial derivatives of a given load component. The empirical constant equals 2.5 microV/V for the assessment of balance calibration or check load data residuals. A value of 0.5 microV/V is recommended for the evaluation of repeat point residuals because, by design, the calculation of these residuals removes errors that are associated with the regression analysis of the data itself. Data from a calibration of a six-component force balance is used to illustrate the application of the new threshold definitions to real{world balance calibration data.

  20. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions.

    Science.gov (United States)

    Jung, HoHyun; Chun, Keyoung Jin; Hong, Jaesoo; Lim, Dohyung

    2015-01-01

    Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m(2)) were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior-posterior, right-diagonal, medial-lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P0.05). These results indicate that optimizing rotation control of the base plate of balance rehabilitation training equipment to induce anterior-posterior and medial-lateral dynamic rotation preferentially can lead to effective balance training. Additional tests with varied speeds and ranges of angles of base plate rotation are expected to be useful as well as an analysis of the balance characteristics considering a balance index that reflects the muscle activity and cooperative characteristics.

  1. Feasibility of Applying Controllable Lubrication to Dynamically Loaded Journal Bearings

    DEFF Research Database (Denmark)

    Estupinan, Edgar Alberto; Santos, Ilmar

    2009-01-01

    A multibody dynamic model of the main mechanical components of a hermetic reciprocating compressor is presented in this work. Considering that some of the mechanical elements are interconnected via thin fluid films, the multibody dynamic model is coupled to the equations from the dynamics...... levels, wear and power losses of the system components. From the point of view of actively controlled lubrication and specifically for the case of dynamically loaded journal bearings, the injection pressure should be controlled in time domain. However, taking into account that the gas pressure...... and reaction forces in a reciprocating compressor have a cyclic behavior, periodic oil pressure injection rules based on the instantaneous crank angle and load bearing condition can be established. In this paper, several bearing configurations working under different oil pressure injection rules conditions...

  2. Influence of linear profile modification and loading conditions on the dynamic tooth load and stress of high contact ratio gears

    Science.gov (United States)

    Lee, Chinwai; Lin, Hsiang Hsi; Oswald, Fred B.; Townsend, Dennis P.

    1990-01-01

    A computer simulation for the dynamic response of high-contact-ratio spur gear transmissions is presented. High contact ratio gears have the potential to produce lower dynamic tooth loads and minimum root stress but they can be sensitive to tooth profile errors. The analysis presented examines various profile modifications under realistic loading conditions. The effect of these modifications on the dynamic load (force) between mating gear teeth and the dynamic root stress is presented. Since the contact stress is dependent on the dynamic load, minimizing dynamic loads will also minimize contact stresses. It is shown that the combination of profile modification and the applied load (torque) carried by a gear system has a significant influence on gear dynamics. The ideal modification at one value of applied load will not be the best solution for a different load. High-contact-ratio gears were found to require less modification than standard low-contact-ratio gears. High-contact-ratio gears are more adversely affected by excess modification than by under modification. In addition, the optimal profile modification required to minimize the dynamic load (hence the contact stress) on a gear tooth differs from the optimal modification required to minimize the dynamic root (bending) stress. Computer simulation can help find the design tradeoffs to determine the best profile modification to satisfy the conflicting constraints of minimizing both the load and root stress in gears which must operate over a range of applied loads.

  3. A load-balanced minimum energy routing algorithm for Wireless Ad Hoc Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Wireless Ad Hoc Sensor Networks (WSNs) have received considerable academia research attention at present. The energy-constraint sensor nodes in WSNs operate on limited batteries, so it is a very important issue to use energy efficiently and reduce power consumption. To maximize the network lifetime, it is essential to prolong each individual node's lifetime through minimizing the transmission energy consumption, so that many minimum energy routing schemes for traditional mobile ad hoc network have been developed for this reason. This paper presents a novel minimum energy routing algorithm named Load-Balanced Minimum Energy Routing (LBMER) for WSNs considering both sensor nodes' energy consumption status and the sensor nodes'hierarchical congestion levels, which uses mixture of energy balance and traffic balance to solve the problem of "hot spots" of WSNs and avoid the situation of"hot spots" sensor nodes using their energy at much higher rate and die much faster than the other nodes. The path router established by LBMER will not be very congested and the traffic will be distributed evenly in the WSNs.Simulation results verified that the LBMER performance is better than that of Min-Hop routing and the existing minimum energy routing scheme MTPR (Total Transmission Power Routing).

  4. Comparison of static and dynamic balance in female collegiate soccer, basketball, and gymnastics athletes.

    Science.gov (United States)

    Bressel, Eadric; Yonker, Joshua C; Kras, John; Heath, Edward M

    2007-01-01

    How athletes from different sports perform on balance tests is not well understood. When prescribing balance exercises to athletes in different sports, it may be important to recognize performance variations. To compare static and dynamic balance among collegiate athletes competing or training in soccer, basketball, and gymnastics. A quasi-experimental, between-groups design. Independent variables included limb (dominant and nondominant) and sport played. A university athletic training facility. Thirty-four female volunteers who competed in National Collegiate Athletic Association Division I soccer (n = 11), basketball (n = 11), or gymnastics (n = 12). To assess static balance, participants performed 3 stance variations (double leg, single leg, and tandem leg) on 2 surfaces (stiff and compliant). For assessment of dynamic balance, participants performed multidirectional maximal single-leg reaches from a unilateral base of support. Errors from the Balance Error Scoring System and normalized leg reach distances from the Star Excursion Balance Test were used to assess static and dynamic balance, respectively. Balance Error Scoring System error scores for the gymnastics group were 55% lower than for the basketball group (P = .01), and Star Excursion Balance Test scores were 7% higher in the soccer group than the basketball group (P = .04). Gymnasts and soccer players did not differ in terms of static and dynamic balance. In contrast, basketball players displayed inferior static balance compared with gymnasts and inferior dynamic balance compared with soccer players.

  5. Prospective dynamic balance control in healthy children and adults.

    Science.gov (United States)

    Austad, Hanne; van der Meer, Audrey L H

    2007-08-01

    Balance control during gait initiation was studied using center of pressure (CoP) data from force plate measurements. Twenty-four participants were divided into four age groups: (1) 2-3 years, (2) 4-5 years, (3) 7-8 years, and (4) adults. Movement in the antero-posterior (CoPy) direction during the initial step was tau-G analyzed, investigating the hypothesis that tau of the CoPy motion-gap (tau(CoPy)), i.e., the time it will take to close the gap at its current closure rate, is tau-coupled onto an intrinsic tau-G guide (tau(G)), by maintaining the relation tau(CoPy )= Ktau(G), for a constant K. Mean percentage of tau-guidance for all groups was >/=99%, resulting in all r(2) exceeding 0.95, justifying an investigation of the regression slope as an estimate of the coupling constant K in the tau-coupling equation. Mean K values decreased significantly with age and were for 2- to 3-year-olds 0.56, for 4- to 5-year-olds 0.50, for 7- to 8-year-olds 0.47, and for adults 0.41. Therefore, the control of dynamic balance develops from the youngest children colliding with the boundaries of the base of support (K > 0.5) to the older children and adults making touch contact (K balance control, a helpful tool in assessing whether a child is following a normal developmental pattern.

  6. Durability of Modified Expanded Polystyrene Concrete after Dynamic Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Wenbo Shi

    2016-01-01

    Full Text Available EPS concrete was produced by mixing the expanded polystyrene spheres (EPS and polymer emulsion and thickener to the matrix concrete, and this concrete had good vibration energy absorption characteristics. Based on the experimental data obtained on EPS volume ratio of 0%, 20%, 30%, and 40% by replacing matrix or coarse aggregate, the two design styles had nearly the same compressive strength. By applying frequency of 5 Hz, 50000 or 100000 times, 40 KN, 50 KN, and 60 KN cyclic loading, it is shown that the higher the inclusion size was, the lower the compressive strength of the EPS concrete would be; the larger the applying dynamic cyclic load was, the more obvious the compressive strength changing would be. Meanwhile, the strength of EPS concrete had no evident change after durability test. The results of this research had practical significance on using EPS concrete in some long-term cyclic dynamic load engineering.

  7. Aeroelastic Deformation and Buckling of Inflatable Wings under Dynamic Loads

    Science.gov (United States)

    Simpson, Andrew; Smith, Suzanne; Jacob, Jamey

    2006-11-01

    Inflatable wings have recently been used to control a vehicle in flight via wing warping. Internal pressure is required to maintain wing shape and externally mounted mechanical actuators are used to asynchronously deform the wing semi-spans for control. Since the rigidity of the inflatable wing varies as a function of inflation pressure, there is a need to relate the wing shape with aerodynamic loads. Via wind tunnel tests, span-wise deformations, twist and flutter have been observed under certain dynamic loading conditions. Photogrammetry techniques are used to measure the static aeroelastic deformation of the wings and videogrammetry is used to examine the dynamic shape changes (flutter). The resulting shapes can be used to determine corresponding aerodynamic characteristics. For particular inflation pressures, buckling can be induced at sufficiently high dynamic loads either through high dynamic pressure or large angle of attack. This results in a set of critical loading parameters. An inflatable winged vehicle would require operation within these limits. The focus of the presentation will be on defining and exploring the unsuitable operating conditions and the effects these conditions have on the operation of the wing.

  8. Discontinuity effects in dynamically loaded tilting pad journal bearings

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder; Vølund, Anders

    2011-01-01

    This paper describes two discontinuity effects that can occur when modelling radial tilting pad bearings subjected to high dynamic loads. The first effect to be treated is a pressure build-up discontinuity effect. The second effect is a contact-related discontinuity that disappears when a contact...

  9. Coupling Dynamics Interlip Coordination in Lower Lip Load Compensation

    Science.gov (United States)

    van Lieshout, Pascal; Neufeld, Chris

    2014-01-01

    Purpose: To study the effects of lower lip loading on lower and upper lip movements and their coordination to test predictions on coupling dynamics derived from studies in limb control. Method: Movement data were acquired using electromagnetic midsagittal articulography under 4 conditions: (a) without restrictions, serving as a baseline; (b) with…

  10. Using Load Balancing to Scalably Parallelize Sampling-Based Motion Planning Algorithms

    KAUST Repository

    Fidel, Adam

    2014-05-01

    Motion planning, which is the problem of computing feasible paths in an environment for a movable object, has applications in many domains ranging from robotics, to intelligent CAD, to protein folding. The best methods for solving this PSPACE-hard problem are so-called sampling-based planners. Recent work introduced uniform spatial subdivision techniques for parallelizing sampling-based motion planning algorithms that scaled well. However, such methods are prone to load imbalance, as planning time depends on region characteristics and, for most problems, the heterogeneity of the sub problems increases as the number of processors increases. In this work, we introduce two techniques to address load imbalance in the parallelization of sampling-based motion planning algorithms: an adaptive work stealing approach and bulk-synchronous redistribution. We show that applying these techniques to representatives of the two major classes of parallel sampling-based motion planning algorithms, probabilistic roadmaps and rapidly-exploring random trees, results in a more scalable and load-balanced computation on more than 3,000 cores. © 2014 IEEE.

  11. Efficient Parallel Data Management Providing Load Balancing Service in Cloud Environment

    Directory of Open Access Journals (Sweden)

    Kavitha.S

    2013-04-01

    Full Text Available Cloud is one of the rapidly developing technologies as it allows convergence of many new areas like scalability, rapid elasticity and broad network access in cloud services. This paper focuses on resource allocation for the parallel data processing, which also occupies a major issue in cloud computing. The current paper aims to study the two major cloud problems i.e. QOS constrained resource allocation and parallel data management problems. The customer demands the cloud provider to host their application with desired SLA such as throughput, response time among others. We have proposed amethodology which is expected to achieve the specified SLA requirements in parallel data management and forecast/identifies the load to be processed by the cloud. This may use the divide and conquerstrategy to predict the load on VM’s (in dividing phase and which will be allocated to that requested customer. We take Nephele, a parallel data processing framework in which job graph issued by thecustomer to be converted into an execution graph on an Iaas cloud system as an example to frame our architecture resulting with minimum response time and efficient load balancing service.

  12. Reliability analysis of wind turbines exposed to dynamic loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2014-01-01

    . Therefore the turbine components should be designed to have sufficient reliability with respect to both extreme and fatigue loads also not be too costly (and safe). This paper presents models for uncertainty modeling and reliability assessment of especially the structural components such as tower, blades...... the reliability of the structural components. Illustrative examples are presented considering uncertainty modeling and reliability assessment for structural wind turbine components exposed to extreme loads and fatigue, respectively.......Wind turbines are exposed to highly dynamic loads that cause fatigue and extreme load effects which are subject to significant uncertainties. Further, reduction of cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources...

  13. Dynamic Regression Intervention Modeling for the Malaysian Daily Load

    Directory of Open Access Journals (Sweden)

    Fadhilah Abdrazak

    2014-05-01

    Full Text Available Malaysia is a unique country due to having both fixed and moving holidays.  These moving holidays may overlap with other fixed holidays and therefore, increase the complexity of the load forecasting activities. The errors due to holidays’ effects in the load forecasting are known to be higher than other factors.  If these effects can be estimated and removed, the behavior of the series could be better viewed.  Thus, the aim of this paper is to improve the forecasting errors by using a dynamic regression model with intervention analysis.   Based on the linear transfer function method, a daily load model consists of either peak or average is developed.  The developed model outperformed the seasonal ARIMA model in estimating the fixed and moving holidays’ effects and achieved a smaller Mean Absolute Percentage Error (MAPE in load forecast.

  14. Dynamic and balanced capacity allocation scheme with uniform bandwidth for OFDM-PON systems

    Science.gov (United States)

    Lei, Cheng; Chen, Hongwei; Chen, Minghua; Yu, Ying; Guo, Qiang; Yang, Sigang; Xie, Shizhong

    2015-03-01

    As the bitrate of orthogonal frequency division multiplexing passive optical network (OFDM-PON) system is continuously increasing, how to effectively allocate the system bandwidth among the huge number of optical network units (ONUs) is one of the key problems before OFDM-PON can be practical deployed. Unlike traditional bandwidth allocation scheme, in this paper, the transmission performance of single ONU is for the first time taken into consideration and optimized. To reduce the manufacturing complexity and fully utilize the processing ability of the receivers, the system bandwidth is equally distributed to the ONUs. Bit loading is used to allocate the total transmission capacity, and power loading is used to guarantee the ONUs have balanced transmission performance even if they operate at different bitrate. In this way, a dynamic and balanced capacity allocation scheme with uniform bandwidth for OFDM-PON systems can be realized. At last, an experimental system is established to verify the feasibility of the proposed scheme, and the influence that the scheme brings to the whole system is also analyzed.

  15. PPOOLEX experiments on dynamic loading with pressure feedback

    Energy Technology Data Exchange (ETDEWEB)

    Puustinen, M.; Laine, J.; Raesaenen, A. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2011-01-15

    This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

  16. PPOOLEX experiments on dynamic loading with pressure feedback

    Energy Technology Data Exchange (ETDEWEB)

    Puustinen, M.; Laine, J.; Raesaenen, A. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2011-01-15

    This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

  17. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions

    Directory of Open Access Journals (Sweden)

    Jung HH

    2015-10-01

    Full Text Available HoHyun Jung,1 Keyoung Jin Chun,2 Jaesoo Hong,2 Dohyung Lim1 1Department of Mechanical Engineering, Sejong University, Seoul, Republic of Korea; 2Smart Welfare Technology Research Group, Korea Institute of Industrial Technology, Cheonan, Republic of Korea Abstract: Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m2 were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior–posterior, right-diagonal, medial–lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P<0.05. The maximum was greater with anterior–posterior and medial–lateral dynamic rotation than with that in other directions (P<0.05. However, there were no statistically significant differences in the frequency of center of body mass deviations from the base of support (P>0.05. These results

  18. Dynamics and mass balance of Taylor Glacier, Antarctica: 2. Force balance and longitudinal coupling

    Science.gov (United States)

    Kavanaugh, J. L.; Cuffey, K. M.

    2009-11-01

    Taylor Glacier, Antarctica, exemplifies an ice sheet outlet that flows through a region of rugged topography and dry climate. In contrast to other well-studied outlets, Taylor Glacier moves very slowly, despite a thickness of order 1 km and driving stresses averaging 1.5 bars. Here we analyze new measurements of glacier geometry and surface velocity to elucidate flow dynamics of Taylor Glacier. Force balance and basal temperatures are calculated at six locations along the glacier's length using an algorithm developed for this study. The effects of stress-gradient coupling on longitudinal flow variations are also examined; we ask whether Kamb and Echelmeyer's (1986) linearized theory adequately describes the observed response of flow to large-amplitude variations in driving stress. The force balance calculations indicate that no basal motion is needed to explain the observed flow of Taylor Glacier. Inferred basal temperatures are within a few degrees of the melting point in regions of kilometer-thick ice and well below the melting point elsewhere; deformation of subfreezing ice largely controls the flow of Taylor Glacier. Basal drags are mostly in the range 0.9 to 1.2 bars, and lateral drags are in the range 0.2 to 0.5 bar. Stress-gradient coupling strongly reduces the variability of velocities along the glacier. The velocity variations can be described as the convolution of a forcing function with a spatial filter, as Kamb and Echelmeyer suggested, but the form of the forcing function differs from the theoretical relation derived for small-amplitude perturbations (the power on driving stress is one, not three).

  19. Damage Characteristic of Interpenetrating Phase Composites under Dynamic Loading

    Institute of Scientific and Technical Information of China (English)

    WANG Fuchi; ZHANG Xu; WANG Yangwei; WANG Lu; MA Zhuang; FAN Qunbo

    2014-01-01

    In order to investigate the damage characteristic of ceramic-metal interpenetrating phase composite (IPC) under dynamic loading, uniaxial dynamic compression was performed to characterize the failure of SiC/Al composite with 15%porosity using a modified Split Hopkinson Pressure Bar (SHPB). High speed photography was used to capture the failure procedure and set up the relationship between deformation and real stress. The deformation control technology was used to obtain collected samples in different deformations under dynamic loading. Micro CT technology was utilized to acquire real damage distribution of these specimens. Moreover, SEM was employed in comparing the damage characteristics in IPC. A summary of the available experimental results showed that IPC without lateral confinement formed double cones. The different features compared with ceramic materials without restraint was shown to be the result of the lateral restraint effect provided by metal phase to ceramics skeleton.

  20. A New Load Residual Threshold Definition for the Evaluation of Wind Tunnel Strain-Gage Balance Data

    Science.gov (United States)

    Ulbrich, N.; Volden, T.

    2016-01-01

    A new definition of a threshold for the detection of load residual outliers of wind tunnel strain-gage balance data was developed. The new threshold is defined as the product between the inverse of the absolute value of the primary gage sensitivity and an empirical limit of the electrical outputs of a strain{gage. The empirical limit of the outputs is either 2.5 microV/V for balance calibration or check load residuals. A reduced limit of 0.5 microV/V is recommended for the evaluation of differences between repeat load points because, by design, the calculation of these differences removes errors in the residuals that are associated with the regression analysis of the data itself. The definition of the new threshold and different methods for the determination of the primary gage sensitivity are discussed. In addition, calibration data of a six-component force balance and a five-component semi-span balance are used to illustrate the application of the proposed new threshold definition to different types of strain{gage balances. During the discussion of the force balance example it is also explained how the estimated maximum expected output of a balance gage can be used to better understand results of the application of the new threshold definition.

  1. The relationship between gait parameters and static and dynamic balance in the elderly

    Directory of Open Access Journals (Sweden)

    Razieh Tabe

    2015-02-01

    Full Text Available Background: The physiological changes and muscle problems can lead to balance disorder and increased risk of falling among the elderly. Therefore, it is necessary to evaluate the factors associated with balance in the elderly, to increase their awareness of the falling risks and to provide them with appropriate assistive devices.. Hence, this study was carried out to investigate the relationship between some gait parameters and static and dynamic balance in the elderly. Methods: In this quasi-experimental study, 44 men and women in two groups (22 per group participated as the study sample. The measured values included step length, stride length, step width, rotating angle of toes, and static and dynamic balance. The static balance was measured with Romberg test and dynamic balance with TUGTU test. Data were analysed by SPSS-15 software using t-test and Pearson correlation coefficient. Results: There was a significant relationship between step length and stride length with static and dynamic balance and between step width and dynamic balance (p0/05. But no significant relationship was reported between step width and static balance and between rotating angle of toes with static and dynamic balance among the elderly. Conclusions: the elderly balance can be improved by decreasing the step length and increasing the stride length, thereby reducing the possibility of their falling.

  2. Plastic instabilities in statically and dynamically loaded spherical vessels

    Energy Technology Data Exchange (ETDEWEB)

    Duffey, Thomas A [Los Alamos National Laboratory; Rodriguez, Edward A [Los Alamos National Laboratory

    2010-01-01

    Significant changes were made in design limits for pressurized vessels in the 2007 version of the ASME Code (Section VIII, Div. 3) and 2008 and 2009 Addenda. There is now a local damage-mechanics based strain-exhaustion limit as well as the well-known global plastic collapse limit. Moreover, Code Case 2564 (Section VIII, Div. 3) has recently been approved to address impulsively loaded vessels. It is the purpose of this paper to investigate the plastic collapse limit as it applies to dynamically loaded spherical vessels. Plastic instabilities that could potentially develop in spherical shells under symmetric loading conditions are examined for a variety of plastic constitutive relations. First, a literature survey of both static and dynamic instabilities associated with spherical shells is presented. Then, a general plastic instability condition for spherical shells subjected to displacement controlled and impulsive loading is given. This instability condition is evaluated for six plastic and visco-plastic constitutive relations. The role of strain-rate sensitivity on the instability point is investigated. Calculations for statically and dynamically loaded spherical shells are presented, illustrating the formation of instabilities as well as the role of imperfections. Conclusions of this work are that there are two fundamental types of instabilities associated with failure of spherical shells. In the case of impulsively loaded vessels, where the pulse duration is short compared to the fundamental period of the structure, one instability type is found not to occur in the absence of static internal pressure. Moreover, it is found that the specific role of strain-rate sensitivity on the instability strain depends on the form of the constitutive relation assumed.

  3. A New Approach of Parallelism and Load Balance for the Apriori Algorithm

    Directory of Open Access Journals (Sweden)

    BOLINA, A. C.

    2013-06-01

    Full Text Available The main goal of data mining is to discover relevant information on digital content. The Apriori algorithm is widely used to this objective, but its sequential version has a low performance when execu- ted over large volumes of data. Among the solutions for this problem is the parallel implementation of the algorithm, and among the parallel implementations presented in the literature that based on Apriori, it highlights the DPA (Distributed Parallel Apriori [10]. This paper presents the DMTA (Distributed Multithread Apriori algorithm, which is based on DPA and exploits the parallelism level of threads in order to increase the performance. Besides, DMTA can be executed over heterogeneous hardware platform, using different number of cores. The results showed that DMTA outperforms DPA, presents load balance among processes and threads, and it is effective in current multicore architectures.

  4. Doubly Exponential Solution for Randomized Load Balancing Models with Markovian Arrival Processes and PH Service Times

    CERN Document Server

    Li, Quan-Lin

    2010-01-01

    In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solution of randomized load balancing models (also known as the supermarket models) with Markovian arrival processes (MAPs) and PH service times. We describe the supermarket model as a system of differential vector equations, and obtain a close-form solution: doubly exponential structure, for the fixed point of the system of differential vector equations. Based on this, we show that the fixed point is decomposited into two groups of information under a product form: the arrival information and the service information, and indicate that the doubly exponential solution to the fixed point is not always unique for more general supermarket models. Furthermore, we analyze the exponential convergence of the current location of the supermarket model to its fixed point, and study the Lipschitz condition in the Kurtz Theorem under MAP arrivals and PH service times. This paper gains a new understanding how the workload probing can...

  5. An Efficient Approach for Generalized Load Balancing in Multipath Packet Switched Networks

    CERN Document Server

    Ali, G G Md Nawaz; Alam, Md Shihabul; Chan, Edward; 10.5121/ijcnc.2010.2211

    2010-01-01

    This paper is a quantitative analysis on packet switched network with a view to generalize load balancing and determination of appropriate routing algorithm in multipath environment. Several routing algorithms have been introduced for routing of packets from source to destination. Some of them route packets accurately with increased workload and some of them drastically cut down the workload. A few of them can find out a minimum workload deviation for both UDP and TCP packets. We simulated these approaches in a well defined simulator, analyzed and evaluated their performance. After expanding our analysis with varying weights and number of paths we found that the recently proposed routing algorithm Mixed Weighted Fair Routing (MWFR) outperforms the existing routing algorithms by reducing the routing and network overhead and saving the scarce bandwidth as well as CPU consumption for packet switching networks.

  6. A Secure and Stable Multicast Overlay Network with Load Balancing for Scalable IPTV Services

    Directory of Open Access Journals (Sweden)

    Tsao-Ta Wei

    2012-01-01

    Full Text Available The emerging multimedia Internet application IPTV over P2P network preserves significant advantages in scalability. IPTV media content delivered in P2P networks over public Internet still preserves the issues of privacy and intellectual property rights. In this paper, we use SIP protocol to construct a secure application-layer multicast overlay network for IPTV, called SIPTVMON. SIPTVMON can secure all the IPTV media delivery paths against eavesdroppers via elliptic-curve Diffie-Hellman (ECDH key exchange on SIP signaling and AES encryption. Its load-balancing overlay tree is also optimized from peer heterogeneity and churn of peer joining and leaving to minimize both service degradation and latency. The performance results from large-scale simulations and experiments on different optimization criteria demonstrate SIPTVMON's cost effectiveness in quality of privacy protection, stability from user churn, and good perceptual quality of objective PSNR values for scalable IPTV services over Internet.

  7. Indirect addressing and load balancing for faster solution to Mandelbrot Set on SIMD architectures

    Science.gov (United States)

    Tomboulian, Sherryl

    1989-01-01

    SIMD computers with local indirect addressing allow programs to have queues and buffers, making certain kinds of problems much more efficient. Examined here are a class of problems characterized by computations on data points where the computation is identical, but the convergence rate is data dependent. Normally, in this situation, the algorithm time is governed by the maximum number of iterations required by each point. Using indirect addressing allows a processor to proceed to the next data point when it is done, reducing the overall number of iterations required to approach the mean convergence rate when a sufficiently large problem set is solved. Load balancing techniques can be applied for additional performance improvement. Simulations of this technique applied to solving Mandelbrot Sets indicate significant performance gains.

  8. Dynamic response of scale models subjected to impact loading

    Science.gov (United States)

    Hillsdon, Graham K.

    1997-05-01

    Presented with the problem of possible failure of large structures due to dynamic loading, and the cost of staging full scale tests. The Oxford University's Department of Engineering Science, supported by British Gas and Rolls Royce, has been scale modeling these events experimentally. The paper looks at two areas of research: (1) The structural integrity of a particular type of Liquified Natural Gas Storage Tank, and its vulnerability to blast loading. (2) The ability of Large Aero Engine Fan blades to withstand impacts associated with birds, stones, ice etc.

  9. Dynamic Response during PEM Fuel Cell Loading-up

    OpenAIRE

    Jun Gou; Pengcheng Li; Xing Yuan; Pucheng Pei

    2009-01-01

    A study on the effects of controlling and operating parameters for a Proton Exchange Membrane (PEM) fuel cell on the dynamic phenomena during the loading-up process is presented. The effect of the four parameters of load-up amplitudes and rates, operating pressures and current levels on gas supply or even starvation in the flow field is analyzed based accordingly on the transient characteristics of current output and voltage. Experiments are carried out in a single fuel cell with an active ar...

  10. The monitoring of pipeline strength in dynamic loading

    Science.gov (United States)

    Proskuriakov, N. E.; Lopa, I. V.

    2017-08-01

    The article considers the strength of a dynamically loaded pipeline at hydraulic blow. We propose, in diagnosing the pipeline quality, to determine the pipe material stress-strain state based on the wave problem solution on the distribution of radial pressure waves in the pipe, both taking into account the falling radial compressive stress waves and the interference of falling and reflected stress waves that form on the free surface. It is shown that the mechanical pressures from the loaded surface to the free surface significantly reduced. The calculations results of the necessary pipe wall thickness the are given at averaging the effective stresses for various transport environments.

  11. Utilization of Model Predictive Control to Balance Power Absorption Against Load Accumulation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Nikhar; Tom, Nathan

    2017-09-01

    Wave energy converter (WEC) control strategies have been primarily focused on maximizing power absorption. The use of model predictive control strategies allows for a finite-horizon, multiterm objective function to be solved. This work utilizes a multiterm objective function to maximize power absorption while minimizing the structural loads on the WEC system. Furthermore, a Kalman filter and autoregressive model were used to estimate and forecast the wave exciting force and predict the future dynamics of the WEC. The WEC's power-take-off time-averaged power and structural loads under a perfect forecast assumption in irregular waves were compared against results obtained from the Kalman filter and autoregressive model to evaluate model predictive control performance.

  12. Determination method of load balance ranges for train operation safety under strong wind

    Institute of Scientific and Technical Information of China (English)

    田红旗

    2015-01-01

    The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift force and overturning moment with different wind speeds and wall heights were calculated. According to the principle of static moment balance of vehicles, the overturning coefficients of trains with different wind speeds and wall heights were obtained. Based on the influence of wind speed and wall height on the aerodynamic performance and the overturning stability of trains, a method of determination of the load balance ranges for the train operation safety was proposed, which made the overturning coefficient have nearly closed interval. A min(|A1|+|A2|), s.t.|A1|→|A2|(A1 refers to the downwind overturning coefficient and A2 refers to the upwind overturning coefficient) was found. This minimum value helps to lower the wall height as much as possible, and meanwhile, guarantees the operation safety of various types of trains under strong wind. This method has been used for the construction and improvement of the windbreak walls along the Lanzhou–Xinjiang railway (from Lanzhou to Urumqi, China).

  13. Modeling the Scheduling Problem of Identical Parallel Machines with Load Balancing by Time Petri Nets

    Directory of Open Access Journals (Sweden)

    Sekhri Larbi

    2014-12-01

    Full Text Available The optimal resources allocation to tasks was the primary objective of the research dealing with scheduling problems. These problems are characterized by their complexity, known as NP-hard in most cases. Currently with the evolution of technology, classical methods are inadequate because they degrade system performance (inflexibility, inefficient resources using policy, etc.. In the context of parallel and distributed systems, several computing units process multitasking applications in concurrent way. Main goal of such process is to schedule tasks and map them on the appropriate machines to achieve the optimal overall system performance (Minimize the Make-span and balance the load among the machines. In this paper we present a Time Petri Net (TPN based approach to solve the scheduling problem by mapping each entity (tasks, resources and constraints to correspondent one in the TPN. In this case, the scheduling problem can be reduced to finding an optimal sequence of transitions leading from an initial marking to a final one. Our approach improves the classical mapping algorithms by introducing a control over resources allocation and by taking into consideration the resource balancing aspect leading to an acceptable state of the system. The approach is applied to a specific class of problems where the machines are parallel and identical. This class is analyzed by using the TiNA (Time Net Analyzer tool software developed in the LAAS laboratory (Toulouse, France.

  14. 云计算环境下的DPSO资源负载均衡算法%DPSO resource load balancing in cloud computing

    Institute of Scientific and Technical Information of China (English)

    冯小靖; 潘郁

    2013-01-01

    Load balancing problem is one of the hot issues in cloud computing. Discrete particle swarm optimization algoritm is used to research load balancing on cloud computing environment. According to dynamic change of resources demand and low require of servers, each resource management node servers as node of the topological structure, and this paper establishes appropriate resource-task model which is resolved by DPSO. Verification results show that the algorithm enhances the utilization ratio and load balancing of resources.%负载均衡问题是云计算研究的热点问题之一.运用离散粒子群算法对云计算环境下的负载均衡问题进行研究,根据云计算环境下资源需求动态变化,并且对资源节点服务器的要求较低的特点,把各个资源节点当做网络拓扑结构中的各个节点,建立相应的资源-任务分配模型,运用离散粒子群算法实现资源负载均衡.验证表明,该算法提高了资源利用率和云计算资源的负载均衡.

  15. Damage and failure rule of rock undergoing uniaxial compressive load and dynamic load

    Institute of Scientific and Technical Information of China (English)

    ZUO Yu-jun; LI Xi-bing; ZHOU Zi-long; MA Chun-de; ZHANG Yi-ping; WANG Wei-hua

    2005-01-01

    For understanding the damage and failure rule of rock under different uniaxial compressive loads and dynamic loads, tests on red sandstone were carried out on Instron 1342 electro-servo controlled testing system with different uniaxial compressive loads of 0, 2, 4 and 6 MPa. It is found that peak stress, peak strain, elastic modulus and total strain energy decrease with the increase of static compressive stress. Based on the test results, the mechanism on damage and failure of rock was analyzed, and according to the equivalent strain hypothesis, a new constitutive model of elastic-plastic damage was established, and then the calculated results with the established model were compared with test results to show a good agreement. Furthermore the rule of releasing ratio of damage strain energy was discussed.

  16. THE DESIGN AND ANALYSIS OF VIBRATION STRUCTURE OF VERTICAL DYNAMIC BALANCING MACHINE

    Institute of Scientific and Technical Information of China (English)

    LiDinggen; CaoJiguang; WangJtmwen; ChenChuanyao

    2004-01-01

    A new type of vibration structure (i.e. supporting system, called swing frame customarily) of vertical dynamic balancing machine has been designed, which is based on an analysis for the swing frame of a traditional double-plane vertical dynamic balancing machine. The static unbalance and couple unbalance can be effectively separated by using the new dynamic balancing machine with the new swing frame. By building the dynamics model, the advantages of the new structure are discussed in detail. The modal and harmonic response are analyzed by using the ANSYS7.0. By comparing the finite element modal analysis with the experimental modal analysis, the natural frequencies and vibration modes are found. There are many spring boards in the new swing frame. Their stiffnesses are different and assorted with each other. Furthermore, there are three sensors on the measuring points. Therefore, the new dynamic balancing machine can measure static unbalance and coupling unbalance directly, and the interaction between them is faint. The result shows that the new vertical dynamic balancing machine is suitable for inertial measurement of flying objects, and can overcome the shortcomings of traditional double-plane vertical dynamic balancing machines, which the effect of plane-separation is inferior. The vertical dynamic balancing machine with the new vibration structure can find wide application in the future. The modelling and analysis of the new vibration structure will provide theoretical basis and practical experience for designing new-type vertical dynamic balancing machines.

  17. A Load-balancing Algorithm Based on Average CPU Load%一种基于CPU负载平均的负载均衡算法

    Institute of Scientific and Technical Information of China (English)

    何龙; 戴新发; 伍华凤; 昌玉芳

    2012-01-01

    与传统分布式集群环境迁移进程不同,虚拟计算环境下的迁移实体是虚拟机,文章针对虚拟机粒度较大的特性,提出了一种基于虚拟机迁移的负载均衡算法.该方法用CPU预测技术避免呈下降趋势时发生不必要迁移.文章的算法采用全局平均的负载均衡策略,只有当负载差值大于一定值才触发迁移.%Different with migrating process in traditional distributed computing environment, the load balancing in virtual computing en-vironment is realized through migrating virtual machine who's intensity is high, this paper presents a load balancing algorithm based on the virtual machine migration. The CPU forecast technology avoid a tiny and temporary load peak value triggering unnecessary migration. This paper uses the global average load-balancing strategy, and trigger migration only when the load difference is greater than a certain value.

  18. Molecular dynamics of shock loading of metals with defects

    Energy Technology Data Exchange (ETDEWEB)

    Belak, J.F. [Lawrence Livermore National Lab., CA (United States)

    1997-12-31

    The finite rise time of shock waves in metals is commonly attributed to dissipative or viscous behavior of the metal. This viscous or plastic behavior is commonly attributed to the motion of defects such as dislocations. Despite this intuitive understanding, the experimental observation of defect motion or nucleation during shock loading has not been possible due to the short time scales involved. Molecular dynamics modeling with realistic interatomic potentials can provide some insight into defect motion during shock loading. However, until quite recently, the length scale required to accurately represent a metal with defects has been beyond the scope of even the most powerful supercomputers. Here, the author presents simulations of the shock response of single defects and indicate how simulation might provide some insight into the shock loading of metals.

  19. Modelling aeolian sand transport using a dynamic mass balancing approach

    Science.gov (United States)

    Mayaud, Jerome R.; Bailey, Richard M.; Wiggs, Giles F. S.; Weaver, Corinne M.

    2017-03-01

    Knowledge of the changing rate of sediment flux in space and time is essential for quantifying surface erosion and deposition in desert landscapes. Whilst many aeolian studies have relied on time-averaged parameters such as wind velocity (U) and wind shear velocity (u*) to determine sediment flux, there is increasing field evidence that high-frequency turbulence is an important driving force behind the entrainment and transport of sand. At this scale of analysis, inertia in the saltation system causes changes in sediment transport to lag behind de/accelerations in flow. However, saltation inertia has yet to be incorporated into a functional sand transport model that can be used for predictive purposes. In this study, we present a new transport model that dynamically balances the sand mass being transported in the wind flow. The 'dynamic mass balance' (DMB) model we present accounts for high-frequency variations in the horizontal (u) component of wind flow, as saltation is most strongly associated with the positive u component of the wind. The performance of the DMB model is tested by fitting it to two field-derived (Namibia's Skeleton Coast) datasets of wind velocity and sediment transport: (i) a 10-min (10 Hz measurement resolution) dataset; (ii) a 2-h (1 Hz measurement resolution) dataset. The DMB model is shown to outperform two existing models that rely on time-averaged wind velocity data (e.g. Radok, 1977; Dong et al., 2003), when predicting sand transport over the two experiments. For all measurement averaging intervals presented in this study (10 Hz-10 min), the DMB model predicted total saltation count to within at least 0.48%, whereas the Radok and Dong models over- or underestimated total count by up to 5.50% and 20.53% respectively. The DMB model also produced more realistic (less 'peaky') time series of sand flux than the other two models, and a more accurate distribution of sand flux data. The best predictions of total sand transport are achieved using

  20. Food composition and acid-base balance: alimentary alkali depletion and acid load in herbivores.

    Science.gov (United States)

    Kiwull-Schöne, Heidrun; Kiwull, Peter; Manz, Friedrich; Kalhoff, Hermann

    2008-02-01

    Alkali-enriched diets are recommended for humans to diminish the net acid load of their usual diet. In contrast, herbivores have to deal with a high dietary alkali impact on acid-base balance. Here we explore the role of nutritional alkali in experimentally induced chronic metabolic acidosis. Data were collected from healthy male adult rabbits kept in metabolism cages to obtain 24-h urine and arterial blood samples. Randomized groups consumed rabbit diets ad libitum, providing sufficient energy but variable alkali load. One subgroup (n = 10) received high-alkali food and approximately 15 mEq/kg ammonium chloride (NH4Cl) with its drinking water for 5 d. Another group (n = 14) was fed low-alkali food for 5 d and given approximately 4 mEq/kg NH4Cl daily for the last 2 d. The wide range of alimentary acid-base load was significantly reflected by renal base excretion, but normal acid-base conditions were maintained in the arterial blood. In rabbits fed a high-alkali diet, the excreted alkaline urine (pH(u) > 8.0) typically contained a large amount of precipitated carbonate, whereas in rabbits fed a low-alkali diet, both pH(u) and precipitate decreased considerably. During high-alkali feeding, application of NH4Cl likewise decreased pH(u), but arterial pH was still maintained with no indication of metabolic acidosis. During low-alkali feeding, a comparably small amount of added NH4Cl further lowered pH(u) and was accompanied by a significant systemic metabolic acidosis. We conclude that exhausted renal base-saving function by dietary alkali depletion is a prerequisite for growing susceptibility to NH4Cl-induced chronic metabolic acidosis in the herbivore rabbit.

  1. A 10 bit 200 MS/s pipeline ADC using loading-balanced architecture in 0.18 μm CMOS

    Science.gov (United States)

    Wang, Linfeng; Meng, Qiao; Zhi, Hao; Li, Fei

    2017-07-01

    A new loading-balanced architecture for high speed and low power consumption pipeline analog-to-digital converter (ADC) is presented in this paper. The proposed ADC uses SHA-less, op-amp and capacitor-sharing technique, capacitor-scaling scheme to reduce the die area and power consumption. A new capacitor-sharing scheme was proposed to cancel the extra reset phase of the feedback capacitors. The non-standard inter-stage gain increases the feedback factor of the first stage and makes it equal to the second stage, by which, the load capacitor of op-amp shared by the first and second stages is balanced. As for the fourth stage, the capacitor and op-amp no longer scale down. From the system’s point of view, all load capacitors of the shared OTAs are balanced by employing a loading-balanced architecture. The die area and power consumption are optimized maximally. The ADC is implemented in a 0.18 μm 1P6M CMOS technology, and occupies a die area of 1.2 × 1.2 mm{}2. The measurement results show a 55.58 dB signal-to-noise-and-distortion ratio (SNDR) and 62.97 dB spurious-free dynamic range (SFDR) with a 25 MHz input operating at a 200 MS/s sampling rate. The proposed ADC consumes 115 mW at 200 MS/s from a 1.8 V supply.

  2. Cost-Sensitive and Load-Balancing Gateway Placement in Wireless Mesh Networks with QoS Constraints

    Institute of Scientific and Technical Information of China (English)

    Feng Zeng; Zhi-Gang Chen

    2009-01-01

    In wireless mesh networks (WMNs), gateway placement is the key to network performance, QoS and construction cost. This paper focuses on the optimization of the cost and load balance in the gateway placement strategy, ensuring the QoS requirements. Firstly, we define a metric for load balance on the gateways, and address the minimum cost and load balancing gateway placement problem. Secondly, we propose two algorithms for gateway placement. One is a heuristic algorithm, which is sensitive to the cost, selects the gateway candidates according to the capacity/cost ratio of the nodes, and optimizes the load balance on the gateways through scanning and shifting methods. The other is a genetic algorithm, which can find the global optimal solution. The two algorithms differ in their computing complexity and the quality of the generated solutions, and thus provide a trade-off for WMN design. At last, simulation is done, and experimental results show that the two algorithms outperform the others. Compared with OPEN/CLOSE, the average cost of gateway placement generated by our algorithms is decreased by 8%~32%, and the load variance on the gateways decreased by 77%~86%. For the genetic algorithm, the performance improvement is at the price of the increase of the CPU execution time.

  3. Dynamic balance of unsymmetrical rotor-bearing system

    Institute of Scientific and Technical Information of China (English)

    黄森林; 刘占生; 苏杰先

    2003-01-01

    The formula is derived for calculating correction weights from motion equations of unsymmetrical ro-tor-bearing system. Two trial weights are required in two trial operations for ea ch balancing plane, and forwardprecession of trial responses are used to calculate the correction weights. Comparative experiments between thismethod and the conventional method are carried out on the test bench. Moreover, this method was used to bal-ance a 600 MW generator-bearing system, it decreased the balancing time and improved the balance accuracy.This method has been proved valid for balancing unsymmetrical rotor-bearing system.

  4. Dynamic response of a poroelastic stratum to moving oscillating load

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The dynamic response of a poroelastic stratum subjected to moving load is studied. The governing dynamic equations for poroelastic medium are solved by using Fourier transform. The general solutions for the stresses and displacements in the transformed domain are established. Based on the general solutions, with the consideration of boundary conditions, the final expressions of stresses and displacements in physical domain are put forward for the three-dimensional single-layer medium. Some numerical solutions for the stresses, displacements and pore fluid pressure are presented and reveal that the response of a poroelastic stratum varies obviously with the moving velocity.

  5. Vortex-induced dynamic loads on a non-spinning volleyball

    Science.gov (United States)

    Qing-ding, Wei; Rong-sheng, Lin; Zhi-jie, Liu

    1988-09-01

    An experiment on vortex-induced dynamic loads on a non-spinning Volleyball was conducted in a wind tunnel. The flow past the Volleyball was visualized, and the aerodynamic load was measured by use of a strain gauge balance. The separation on the Volleyball was measured with hot-film. The experimental results suggest that under the action of an unstable tail vortex system the separation region is changeable, and that the fluctuation of drag and lateral forces is the same order of magnitude as the mean drag, no matter whether the seam of the Volleyball is symmetric or asymmetric, with regard to the flow. Based on the experimental data a numerical simulation of Volleyball swerve motion was made.

  6. Parametric Dynamic Load Prediction of a Narrow Gauge Rocket Sled

    Science.gov (United States)

    2006-12-01

    sensitivity of dynamic loading to design parameter variation was investigated numerically by Nedimovic (2004), and sensitivity to changes in rail...measured data sets and to give insight into model behavior with regard to input parameters to help determine initial model sensitivities and design...LSR and CO tests was considered to be 74 WL 0.00 #115 Payload Aft Attachment Vertical Force ( SGB ) #138 Payload Aft Attachment Lateral Force

  7. LBMR: Load-Balanced Multipath Routing for Wireless Data-Intensive Transmission in Real-Time Medical Monitoring.

    Science.gov (United States)

    Tseng, Chinyang Henry

    2016-05-31

    In wireless networks, low-power Zigbee is an excellent network solution for wireless medical monitoring systems. Medical monitoring generally involves transmission of a large amount of data and easily causes bottleneck problems. Although Zigbee's AODV mesh routing provides extensible multi-hop data transmission to extend network coverage, it originally does not, and needs to support some form of load balancing mechanism to avoid bottlenecks. To guarantee a more reliable multi-hop data transmission for life-critical medical applications, we have developed a multipath solution, called Load-Balanced Multipath Routing (LBMR) to replace Zigbee's routing mechanism. LBMR consists of three main parts: Layer Routing Construction (LRC), a Load Estimation Algorithm (LEA), and a Route Maintenance (RM) mechanism. LRC assigns nodes into different layers based on the node's distance to the medical data gateway. Nodes can have multiple next-hops delivering medical data toward the gateway. All neighboring layer-nodes exchange flow information containing current load, which is the used by the LEA to estimate future load of next-hops to the gateway. With LBMR, nodes can choose the neighbors with the least load as the next-hops and thus can achieve load balancing and avoid bottlenecks. Furthermore, RM can detect route failures in real-time and perform route redirection to ensure routing robustness. Since LRC and LEA prevent bottlenecks while RM ensures routing fault tolerance, LBMR provides a highly reliable routing service for medical monitoring. To evaluate these accomplishments, we compare LBMR with Zigbee's AODV and another multipath protocol, AOMDV. The simulation results demonstrate LBMR achieves better load balancing, less unreachable nodes, and better packet delivery ratio than either AODV or AOMDV.

  8. Guidelines for Low Mass and Low Inertia Dynamic Balancing of Mechanisms and Robotics

    NARCIS (Netherlands)

    van der Wijk, V.; Herder, Justus Laurens; Kröger, Torsten; Wahl, Friedrich M.

    2009-01-01

    Dynamic balance of machines is important when, for example, high precision in combination with low cycle times is necessary. One of the major problems with dynamic balancing is that considerable mass and considerable inertia need to be added to the mechanism. So far, only a few studies have been car

  9. A screw-based dynamic balancing approach, applied to a 5-bar mechanism

    NARCIS (Netherlands)

    de Jong, Jan Johannes; van Dijk, Johannes; Herder, Justus Laurens

    2016-01-01

    Dynamic balancing aims to reduce or eliminate the shaking base reaction forces and moments of mechanisms, in order to minimize vibration and wear. The derivation of the dynamic balance conditions requires significant algebraic effort, even for simple mechanisms. In this study, a screw-based balancin

  10. Dynamic Stability and Gravitational Balancing of Multiple Extended Bodies

    Science.gov (United States)

    Quadrelli, Marco

    2008-01-01

    Feasibility of a non-invasive compensation scheme was analyzed for precise positioning of a massive extended body in free fall using gravitational forces influenced by surrounding source masses in close proximity. The N-body problem of classical mechanics is a paradigm used to gain insight into the physics of the equivalent N-body problem subject to control forces. The analysis addressed how a number of control masses move around the proof mass so that the proof mass position can be accurately and remotely compensated when exogenous disturbances are acting on it, while its sensitivity to gravitational waves remains unaffected. Past methods to correct the dynamics of the proof mass have considered active electrostatic or capacitive methods, but the possibility of stray capacitances on the surfaces of the proof mass have prompted the investigation of other alternatives, such as the method presented in this paper. While more rigorous analyses of the problem should be carried out, the data show that, by means of a combined feedback and feed-forward control approach, the control masses succeeded in driving the proof mass along the specified trajectory, which implies that the proof mass can, in principle, be balanced via gravitational forces only while external perturbations are acting on it. This concept involves the dynamic stability of a group of massive objects interacting gravitationally under active control, and can apply to drag-free control of spacecraft during missions, to successor gravitational wave space borne sensors, or to any application requiring flying objects to be precisely controlled in position and attitude relative to another body via gravitational interactions only.

  11. Maximum Allowable Dynamic Load of Mobile Manipulators with Stability Consideration

    Directory of Open Access Journals (Sweden)

    Heidary H. R.

    2015-09-01

    Full Text Available High payload to mass ratio is one of the advantages of mobile robot manipulators. In this paper, a general formula for finding the maximum allowable dynamic load (MADL of wheeled mobile robot is presented. Mobile manipulators operating in field environments will be required to manipulate large loads, and to perform such tasks on uneven terrain, which may cause the system to reach dangerous tip-over instability. Therefore, the method is expanded for finding the MADL of mobile manipulators with stability consideration. Moment-Height Stability (MHS criterion is used as an index for the system stability. Full dynamic model of wheeled mobile base and mounted manipulator is considered with respect to the dynamic of non-holonomic constraint. Then, a method for determination of the maximum allowable loads is described, subject to actuator constraints and by imposing the stability limitation as a new constraint. The actuator torque constraint is applied by using a speed-torque characteristics curve of a typical DC motor. In order to verify the effectiveness of the presented algorithm, several simulation studies considering a two-link planar manipulator, mounted on a mobile base are presented and the results are discussed.

  12. Dynamic Response of RPC-Filled Steel Tubular Columns with High Load Carrying Capacity Under Axial Impact Loading

    Institute of Scientific and Technical Information of China (English)

    TIAN Zhimin; WU Ping'an; JIA Jianwei

    2008-01-01

    Experimental investigation into impact-resistant behavior of reactive powder concrete (RPC)-filled steel tubular columns was conducted, and dynamic response of the columns under axial impact loading was studied by means of numerical simulation method.Increase coefficient of load carrying capacity and ratio of load carrying capacity between steel tube and RPC core of columns were obtained.

  13. Relationship between Core Stability Muscle Endurance and Static and Dynamic Balance in Basketball Players

    OpenAIRE

    farzaneh saki; masumeh Baghban

    2016-01-01

    Objective: Balancing is the most basic function of the neuromuscular system in performing all simple and complex activities that contribute to health-related physical fitness. Core stability may be a contributing factor to static and dynamic balance. The aim of this study was to investigate the relationship between core stability muscle endurance and static and dynamic balance in basketball players. Methods: 100 basketball players (50 female and 50 male players) were selected randomly bas...

  14. Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2015-10-01

    Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.

  15. Assessment of dynamic balance via measurement of lower extremities tortuosity.

    Science.gov (United States)

    Eltoukhy, Moataz; Kuenze, Christopher; Jun, Hyung-Pil; Asfour, Shihab; Travascio, Francesco

    2015-03-01

    Tortuosity describes how twisted or how much curvature is present in an observed movement or path. The purpose of this study was to investigate the differences in segmental tortuosity between Star Excursion Balance Test (SEBT) reach directions. Fifteen healthy participants completed this study. Participants completed the modified three direction (anterior, posteromedial, posterolateral) SEBT with three-dimensional motion analysis using an 8 camera BTS Smart 7000DX motion analysis system. The tortuosity of stance limb retro-reflective markers was then calculated and compared between reach directions using a 1 × 3 ANOVA with repeated measures, while the relationship between SEBT performance and tortuosity was established using Pearson product moment correlations. Anterior superior iliac spine tortuosity was significantly greater (p < 0.001) and lateral knee tortuosity was lesser (p = 0.018) in the anterior direction compared to the posteromedial and posterolateral directions. In addition, second metatarsal tortuosity was greater in the anterior reach direction when compared to posteromedial direction (p = 0.024). Tortuosity is a novel biomechanical measurement technique that provides an assessment of segmental movement during common dynamic tasks such as the SEBT. This enhanced level of detail compared to more global measures of joint kinematic may provide insight into compensatory movement strategies adopted following lower extremity joint injury.

  16. Balanced and Transient Dynamics of Deep and Shallow Hadley Circulations

    Science.gov (United States)

    Gonzalez, A. O.; Mora Rojas, G.; Taft, R.; Schubert, W. H.

    2014-12-01

    We examine the balanced and transient dynamics of large-scale overturning circulations in the tropical atmosphere using idealized equatorial β-plane models. When deep diabatic heating in the Intertropical Convergence Zone (ITCZ) is prescribed as slowly varying with time, the deep Hadley circulation is of first order importance. In the absence of deep diabatic heating, the interior circulation associated with Ekman pumping cannot penetrate deep into the troposphere because the resistance of fluid parcels to horizontal motion (i.e., inertial stability) is significantly smaller than their resistance to vertical motion (i.e., static stability). In this scenario, only a shallow Hadley circulation exists. The meridional asymmetry between the winter and summer deep and shallow Hadley cells is attributed to the anisotropy of the inertial stability parameter, and as the ITCZ widens meridionally or as the forcing involves higher vertical wavenumbers, the asymmetry between the winter and summer cells increases. When we prescribe both a slow and fast "switch-on" deep diabatic heating, we learn that inertia-gravity waves propagate in the meridional direction away from the ITCZ and bounce back at critical latitutes in the zonally symmetric framework. When the assumption of zonal symmetry is relaxed, we find that inertia-gravity waves propagate away from the ITCZ in not only the meridional direction but also in the zonal direction.

  17. Emergence of Balance from a model of Social Dynamics

    CERN Document Server

    Agbanusi, Ikemefuna

    2016-01-01

    We propose a model for social dynamics on a network. In this model each actor holds a position on some issue, actors and their opinions being associated to vertices of the graph, and, additionally, the actors hold opinions of one another, with these opinions being associated to edges in the graph. These quantities are allowed to evolve according to the gradient flow of a natural free energy. We show that for a small spread in opinions the model converges to a consensus state, where all actors hold the same position. For a larger spread in opinion there is a phase transition marked by the birth of a second stable state: in addition to the consensus state there is a second polarized or partisan state. This state, when it exists, is conjectured to be global energy minimizer, with the consensus state being a local energy minimizer. We derive an energy inequality which supports this. Interestingly, all of the steady states we find, with the exception of the consensus state, are either balanced (in the sense of Hei...

  18. Dynamic Difficulty Balancing for Cautious Players and Risk Takers

    Directory of Open Access Journals (Sweden)

    Guy Hawkins

    2012-01-01

    Full Text Available Dynamic balancing of game difficulty can help cater for different levels of ability in players. However, performance in some game tasks depends on not only the player's ability but also their desire to take risk. Taking or avoiding risk can offer players its own reward in a game situation. Furthermore, a game designer may want to adjust the mechanics differently for a risky, high ability player, as opposed to a risky, low ability player. In this work, we describe a novel modelling technique known as particle filtering which can be used to model various levels of player ability while also considering the player's risk profile. We demonstrate this technique by developing a game challenge where players are required to make a decision between a number of possible alternatives where only a single alternative is correct. Risky players respond faster but with more likelihood of failure. Cautious players wait longer for more evidence, increasing their likelihood of success, but at the expense of game time. By gathering empirical data for the player's response time and accuracy, we develop particle filter models. These models can then be used in real-time to categorise players into different ability and risk-taking levels.

  19. Static and Dynamic Balance in Congenital Severe to Profound Hearing-Impaired Children

    Directory of Open Access Journals (Sweden)

    Farideh HajiHeydari

    2011-09-01

    Full Text Available Background and Aim: Research conducted since the early 1900s has consistently identified differences between deaf and hearing children on performance of a wide variety of motor tasks, most notably balance. Our study was performed to test static and dynamic balance skills in congenital severe to profound hearing impaired children in comparison with normal age-matched children.Methods: This cross-sectional study was conducted on 30 severe to profound hearing impaired and 40 normal children with age 6 to 10 years old. Bruininks-Oseretsky test of motor proficiency 2, balance subset with 9 parts was used for evaluation of balance skills.Results: Hearing-impaired children showed 16.7 to 100% fail results in 7 parts of the balance subset. In normal children fail result was revealed just in 3 parts of the balance subset from 2.5 to 57.5%, and differences between two groups were significant (p<0.0001. There was a significant difference between two groups in two static balance skills of standing on one leg on a line and standing on one leg on a balance beam with eyes closed (p<0.0001.conclusion: It seems that development of static balance skills are longer than dynamic ones. Because severe to profound hearing-impaired children showed more weakness than normal children in both static and dynamic balance abilities, functional tests of balance proficiency can help to identify balance disorders in these children.

  20. Implications of Dynamic Loading and Changing Climate on Mercury Bioaccumulation in a Planktivorous Fish (Orthodon microlepidotus)

    Science.gov (United States)

    Carroll, R. W. H.; Flickinger, A.; Warwick, J. J.; Schumer, R.

    2015-12-01

    A bioenergetic and mercury (Hg) mass balance (BioHg) model is developed for the Sacramento blackfish (Orthodon microlepidotus), a filter feeding cyprinid found in northern California and Nevada. Attention focuses on the Lahontan Reservoir in northern Nevada, which receives a strong temporally varying load of dissolved methylmercury (DMeHg) from the Carson River. Hg loads are the result of contaminated bank erosion during high flows and diffusion from bottom sediments during low flows. Coupling of dynamic reservoir loading with periods of maximum plankton growth and maximum fish consumption rates are required to explain the largest body burdens observed in the planktivore. In contrast, the large body burdens cannot be achieved using average water column concentrations. The United States Bureau of Reclamation has produced future streamflow estimates for 2000-2099 using 112 CMIP3 climate projections and the Variable Infiltration Capacity (VIC) model. These are used to drive a fully dynamic Hg transport model to assess changes in contaminant loading to the reservoir and implications on planktivorous bioaccumulation. Model results suggest the future loads of DMeHg entering the Lahontan Reservoir will decrease most significantly in the spring and summer due to channel width increases and depth decreases in the Carson River which reduce bank erosion over the century. The modeled concentrations of DMeHg in the reservoir are expected to increase during the summer due to a decrease in reservoir volume affecting the concentrations more than the decrease in loads, and the model results show that bioaccumulation levels may increase in the upstream sections of the reservoir while maintaining contamination levels above the federal action limit for human consumption in the lower reservoir.

  1. Dynamic Loading of Carrara Marble in a Heated State

    Science.gov (United States)

    Wong, Louis Ngai Yuen; Li, Zhihuan; Kang, Hyeong Min; Teh, Cee Ing

    2017-06-01

    Useable land is a finite space, and with a growing global population, countries have been exploring the use of underground space as a strategic resource to sustain the growth of their society and economy. However, the effects of impact loading on rocks that have been heated, and hence the integrity of the underground structure, are still not fully understood and has not been included in current design standards. Such scenarios include traffic accidents and explosions during an underground fire. This study aims to provide a better understanding of the dynamic load capacity of Carrara marble at elevated temperatures. Dynamic uniaxial compression tests are performed on Carrara marble held at various temperatures using a split-Hopkinson Pressure Bar (SHPB) setup with varying input force. A customized oven is included in the SHPB setup to allow for testing of the marble specimens in a heated state. After the loading test, a three-wave analysis is performed to obtain the dynamic stress-strain curve of the specimen under loading. The fragments of the failed specimens were also collected and dry-sieved to obtain the particle size distribution. The results reveal that the peak stress of specimens that have been heated is negatively correlated with the heating temperature. However, the energy absorbed by the specimens at peak stress at all temperatures is similar, indicating that a significant amount of energy is dissipated via plastic deformation. Generally, fragment size is also found to show a negative correlation with heating temperature and loading pressure. However, in some cases this relationship does not hold true, probably due to the occurrence of stress shadowing. Linear Elastic Fracture Mechanics has been found to be generally applicable to specimens tested at low temperatures; but at higher temperatures, Elastic-Plastic Fracture Mechanics will give a more accurate prediction. Another contribution of this study is to show that other than the peak stress of the

  2. Active dynamic balancing unit for controlled shaking force and shaking moment balancing

    NARCIS (Netherlands)

    van der Wijk, V.; Herder, Justus Laurens

    2010-01-01

    For a mechanism with many elements that needs to be shaking-force and shaking-moment balanced with a low addition of mass, a low addition of inertia, and a low addition of complexity, the use of actively computer-controlled balancing elements is promising. With these actively controlled elements the

  3. Dynamic impedance of piles in visco-elastic material considering axial loads

    Institute of Scientific and Technical Information of China (English)

    JIANG Jian-guo; ZHOU Xu-hong; ZHANG Jia-sheng

    2005-01-01

    The dynamic impedance function of pile in visco-elastie material considering axial loads under lateral dynamic force was analyzed, and the beam dynamic differential equation was used to induce the dynamic impedance function. After analyzing the edge conditions, the dynamic impedance functions were deduced. Contrasted with the result that does not consider axial loads, the axial loads have obvious influence on the dynamic impedance function.And the results show that the dimensionless prarmeter of the dynamic impedance will change from 6 % to 9 % when considering axial loads, and dimensionless prarmeter of the dynamic impedance of the coupling horizontal-sway will increase by 31 %.

  4. Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

    OpenAIRE

    Zhou, Zilong; Li, Xibing; Zou, Yang; Jiang, Yihui; Li, Guonan

    2014-01-01

    Rocks in underground projects at great depth, which are under high static stresses, may be subjected to dynamic disturbance at the same time. In our previous work (Li et al. Int J Rock Mech Min Sci 45(5):739–748, 2008), the dynamic compressive behaviour of pre-stressed rocks was investigated using coupled-load equipment. The current work is devoted to the investigation of the dynamic tensile behaviour of granite rocks under coupled loads using the Brazilian disc (BD) method with the aid of a ...

  5. Relationship between Core Stability Muscle Endurance and Static and Dynamic Balance in Basketball Players

    Directory of Open Access Journals (Sweden)

    farzaneh saki

    2016-03-01

    Full Text Available Objective: Balancing is the most basic function of the neuromuscular system in performing all simple and complex activities that contribute to health-related physical fitness. Core stability may be a contributing factor to static and dynamic balance. The aim of this study was to investigate the relationship between core stability muscle endurance and static and dynamic balance in basketball players. Methods: 100 basketball players (50 female and 50 male players were selected randomly based on the including criteria.To evaluate core stability muscle strength, a set of tests from core stability exercises was used. Static and dynamic balance were evaluated by Bass Stick and Y balance test respectively. Normality of the data was evaluated using the Kolmogorov Smirnoff test. Data analysis was performed by Spearman product moment coefficient test and independent samples t test. Significant level of p&le0/05 was used in all statistical analyses. Results: Results of t-test showed no significant difference between static balance in boys and girls, while significant differences were observed between dynamic balance and core stability in males and females. In other words, core stability and dynamic balance in boys were more than girls. Also, the results of correlation analysis showed a significant relationship between core stability and dynamic balance (p=0.00 However, no significant relationship was observed between core stability and static balance (p=0.451. Conclusion: Due to the correlation between muscle endurance and dynamic balance in the present study, it can be implied that core stability exercises can improve balance.

  6. Dynamic Configure Equal Cost Multi-Paths to Achieve Load Balance in Wireless Sensor Networks%基于动态配置等价多路径技术的无线传感器网络负载均衡算法研究∗

    Institute of Scientific and Technical Information of China (English)

    王璟; 王利利; 游金阔; 杨挺

    2015-01-01

    With the development of Internet of Things(IoTs),wireless sensor networks,as the infrastructure of IoTs, should bear more and more various transmission services. The narrow wireless bandwidth becomes the first restrictive factors. Shunting flow to achieve load balance is the effective way to improve the bearing capacity of communication network. This paper integrated Equal-Cost Multi-Paths(ECMP)technique and WSN’s self-organized characteristics,in which the self-organized connection and multi-hops transmission model of WSN provide more than one shortest paths from traffic source to the destination sensor node,and then ECMP can equally apportioned traffic on these available e-qual cost multi-paths to stabilize huge traffic. It proved that the traditional ECMP model,configured all of nodes with ECMP function,will increase the overhead expenses,and even make heavier traffic load in some special cases. To solve these problems,this paper proposed the dynamic configuration ECMP algorithm-DC-ECMP. In the algorithm,it defined the traffic volume conservation constraint and the wireless transmitting bandwidth upper bound constraint, made the minimizing the maximum link utilization rate as objective function,and establish the multi-constraint optimi-zation model. Using the maximum link utilization rate and node’s degree to calculate the priority of configuration EC-MP function,each node can be dynamic configuration and achieve the optimal network’s transmitting performance. In our evaluation with simulations,the performance of DC-ECMP is measured and compared with PPV algorithms. Based on the experimental results,DC-ECMP outperforms existing algorithms in reduce the maximum link utilization rate, short the transmitting latency 9.9 ms,and save the networks’ resource consumption 4.06%.%随着物联网应用的推广,作为底层核心构件的传感器网络所承载传输业务成激增趋势,使得窄带宽无线信道成为了制约物联网应用的首要因素。

  7. Assessing Numerical Error in Structural Dynamics Using Energy Balance

    Directory of Open Access Journals (Sweden)

    Rabindranath Andujar

    2013-01-01

    Full Text Available This work applies the variational principles of Lagrange and Hamilton to the assessment of numerical methods of linear structural analysis. Different numerical methods are used to simulate the behaviour of three structural configurations and benchmarked in their computation of the Lagrangian action integral over time. According to the principle of energy conservation, the difference at each time step between the kinetic and the strain energies must equal the work done by the external forces. By computing this difference, the degree of accuracy of each combination of numerical methods can be assessed. Moreover, it is often difficult to perceive numerical instabilities due to the inherent complexities of the modelled structures. By means of the proposed procedure, these complexities can be globally controlled and visualized in a straightforward way. The paper presents the variational principles to be considered for the collection and computation of the energy-related parameters (kinetic, strain, dissipative, and external work. It then introduces a systematic framework within which the numerical methods can be compared in a qualitative as well as in a quantitative manner. Finally, a series of numerical experiments is conducted using three simple 2D models subjected to the effect of four different dynamic loadings.

  8. Development of an Efficient Secured E-Learning Tool through Smart Firewall Load Balancing Technique

    Directory of Open Access Journals (Sweden)

    R. Bala Krishnan

    2012-05-01

    Full Text Available E-Learning has definite benefits over traditional classroom training. For E-Learning, various ELearning Tools have been proposed. However, users need to wait for long time to get response from Knowledge Database, which is called as E-Learning Data Server, if many users are online. And providing security to this E-Server is a challenging one. To address these issues, this work has proposed an efficient E-Learning Model through Smart Firewall Load Balancing Technique. Firewall is a device which is designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass. Many personal computer Operating Systems contains software-based firewalls which is used to protect the system against threats from the public Internet. Many Routers that pass data between Networks contain firewall components and, conversely, many firewalls can perform basic routing functions. Existing Firewall Technologies such as Cisco PIX Firewalls and Checkpoint FireWall-1 provide various software tools that allowing firewalls as Clustered or Grouped and these Configured Firewalls will share their loads. The main objectives of the existing technologies are to improve the Resource Utilization along with performance and Security. This is one of the serious problems. ie the required performance can’t be achieved. This research work is introduced a Adaptive Scheduler, which focuses both the Performance and Security along with Resource Utilization, and also this proposed approach reduced the firewall rules, which minimize the delay and hence this proposed work improved the Throughput, which improved the E-Server Performance in terms of Throughput, Delay and Security Strength.

  9. Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

    Science.gov (United States)

    Zhou, Zilong; Li, Xibing; Zou, Yang; Jiang, Yihui; Li, Guonan

    2014-03-01

    Rocks in underground projects at great depth, which are under high static stresses, may be subjected to dynamic disturbance at the same time. In our previous work (Li et al. Int J Rock Mech Min Sci 45(5):739-748, 2008), the dynamic compressive behaviour of pre-stressed rocks was investigated using coupled-load equipment. The current work is devoted to the investigation of the dynamic tensile behaviour of granite rocks under coupled loads using the Brazilian disc (BD) method with the aid of a high-speed camera. Through wave analyses, stress measurements and crack photography, the fundamental problems of BD tests, such as stress equilibrium and crack initiation, were investigated by the consideration of different loading stresses with abruptly or slowly rising stress waves. The specially shaped striker method was used for the coupled-load test; this generates a slowly rising stress wave, which allows gradual stress accumulation in the specimen, whilst maintaining the load at both ends of the specimen in an equilibrium state. The test results showed that the tensile strength of the granite under coupled loads decreases with increases in the static pre-stresses, which might lead to modifications of the blasting design or support design in deep underground projects. Furthermore, the failure patterns of specimens under coupled loads have been investigated.

  10. Asymptotic Stability and Balanced Growth Solution of the Singular Dynamic Input-Output System*

    Institute of Scientific and Technical Information of China (English)

    ChonghuiGuo; HuanwenTang

    2004-01-01

    The dynamic input-output system is well known in economic theory and practice. In this paper the asymptotic stability and balanced growth solution of the dynamic input-output system are considered. Under three natural assumptions, we obtain four theorems about asymptotic stability and balanced growth solution of the dynamic input-output system and bring together in a unified manner some contributions scattered in the literature.

  11. Accelerating Multiple Compound Comparison Using LINGO-Based Load-Balancing Strategies on Multi-GPUs

    Directory of Open Access Journals (Sweden)

    Chun-Yuan Lin

    2015-01-01

    Full Text Available Compound comparison is an important task for the computational chemistry. By the comparison results, potential inhibitors can be found and then used for the pharmacy experiments. The time complexity of a pairwise compound comparison is O(n2, where n is the maximal length of compounds. In general, the length of compounds is tens to hundreds, and the computation time is small. However, more and more compounds have been synthesized and extracted now, even more than tens of millions. Therefore, it still will be time-consuming when comparing with a large amount of compounds (seen as a multiple compound comparison problem, abbreviated to MCC. The intrinsic time complexity of MCC problem is O(k2n2 with k compounds of maximal length n. In this paper, we propose a GPU-based algorithm for MCC problem, called CUDA-MCC, on single- and multi-GPUs. Four LINGO-based load-balancing strategies are considered in CUDA-MCC in order to accelerate the computation speed among thread blocks on GPUs. CUDA-MCC was implemented by C+OpenMP+CUDA. CUDA-MCC achieved 45 times and 391 times faster than its CPU version on a single NVIDIA Tesla K20m GPU card and a dual-NVIDIA Tesla K20m GPU card, respectively, under the experimental results.

  12. Accelerating Multiple Compound Comparison Using LINGO-Based Load-Balancing Strategies on Multi-GPUs.

    Science.gov (United States)

    Lin, Chun-Yuan; Wang, Chung-Hung; Hung, Che-Lun; Lin, Yu-Shiang

    2015-01-01

    Compound comparison is an important task for the computational chemistry. By the comparison results, potential inhibitors can be found and then used for the pharmacy experiments. The time complexity of a pairwise compound comparison is O(n (2)), where n is the maximal length of compounds. In general, the length of compounds is tens to hundreds, and the computation time is small. However, more and more compounds have been synthesized and extracted now, even more than tens of millions. Therefore, it still will be time-consuming when comparing with a large amount of compounds (seen as a multiple compound comparison problem, abbreviated to MCC). The intrinsic time complexity of MCC problem is O(k (2) n (2)) with k compounds of maximal length n. In this paper, we propose a GPU-based algorithm for MCC problem, called CUDA-MCC, on single- and multi-GPUs. Four LINGO-based load-balancing strategies are considered in CUDA-MCC in order to accelerate the computation speed among thread blocks on GPUs. CUDA-MCC was implemented by C+OpenMP+CUDA. CUDA-MCC achieved 45 times and 391 times faster than its CPU version on a single NVIDIA Tesla K20m GPU card and a dual-NVIDIA Tesla K20m GPU card, respectively, under the experimental results.

  13. Load-balancing techniques for a parallel electromagnetic particle-in-cell code

    Energy Technology Data Exchange (ETDEWEB)

    PLIMPTON,STEVEN J.; SEIDEL,DAVID B.; PASIK,MICHAEL F.; COATS,REBECCA S.

    2000-01-01

    QUICKSILVER is a 3-d electromagnetic particle-in-cell simulation code developed and used at Sandia to model relativistic charged particle transport. It models the time-response of electromagnetic fields and low-density-plasmas in a self-consistent manner: the fields push the plasma particles and the plasma current modifies the fields. Through an LDRD project a new parallel version of QUICKSILVER was created to enable large-scale plasma simulations to be run on massively-parallel distributed-memory supercomputers with thousands of processors, such as the Intel Tflops and DEC CPlant machines at Sandia. The new parallel code implements nearly all the features of the original serial QUICKSILVER and can be run on any platform which supports the message-passing interface (MPI) standard as well as on single-processor workstations. This report describes basic strategies useful for parallelizing and load-balancing particle-in-cell codes, outlines the parallel algorithms used in this implementation, and provides a summary of the modifications made to QUICKSILVER. It also highlights a series of benchmark simulations which have been run with the new code that illustrate its performance and parallel efficiency. These calculations have up to a billion grid cells and particles and were run on thousands of processors. This report also serves as a user manual for people wishing to run parallel QUICKSILVER.

  14. An Energy-Efficient, Load Balanced Distributed Clustering and Routing Protocol for Large Scale WSNs

    Directory of Open Access Journals (Sweden)

    Yousef Matinfard

    2013-06-01

    Full Text Available A wireless network consisting of a large number of small sensors with low-power transceivers can be an effective tool for gathering data in a variety of environments. These sensor nodes have some constraints due to limited energy, storage capacity and computing power. The energy consumed to route data from the sensor node to its destination raises as a critical issue in designing wireless sensor network routing protocols. In order to prolong the lifetime of wireless sensor networks, this study presents a multi-hop routing protocol with distributed clustering (ELDRL. First, in order to overcome the defect that the clusters distribute unevenly, ELDRL selects nodes as a cluster-head with regard to neighbor cluster-heads. Second, it partitions the network into different layers of clusters. Cluster heads in each layer cooperates with the adjacent layer to transmit sensor’s data to the base station. ELDRL spreads the workload across the sensor network, load balancing reduces hot spots in the sensor network and increases the energy lifetime of the sensor network. Moreover, the protocol not only increases the scalability but also decreases the traffic of WSN. Simulation results show that the scheme is more efficient compared with LEACH.

  15. Modulation Codes for Flash Memory Based on Load-Balancing Theory

    CERN Document Server

    Zhang, Fan

    2009-01-01

    In this paper, we consider modulation codes for practical multilevel flash memory storage systems with cell levels. Instead of maximizing the lifetime of the device [Ajiang-isit07-01, Ajiang-isit07-02, Yaakobi_verdy_siegel_wolf_allerton08, Finucane_Liu_Mitzenmacher_aller08], we maximize the average amount of information stored per cell-level, which is defined as storage efficiency. Using this framework, we show that the worst-case criterion [Ajiang-isit07-01, Ajiang-isit07-02, Yaakobi_verdy_siegel_wolf_allerton08] and the average-case criterion [Finucane_Liu_Mitzenmacher_aller08] are two extreme cases of our objective function. A self-randomized modulation code is proposed which is asymptotically optimal, as, for an arbitrary input alphabet and i.i.d. input distribution. In practical flash memory systems, the number of cell-levels is only moderately large. So the asymptotic performance as may not tell the whole story. Using the tools from load-balancing theory, we analyze the storage efficiency of the self-ra...

  16. Load controller and method to enhance effective capacity of a photovotaic power supply using a dynamically determined expected peak loading

    Science.gov (United States)

    Perez, Richard

    2003-04-01

    A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The expected peak loading of the variable load can be dynamically determined within a defined time interval with reference to variations in the variable load.

  17. The dynamics of gait transitions: effects of grade and load.

    Science.gov (United States)

    Diedrich, F J; Warren, W H

    1998-03-01

    Diedrich and Warren (1995a) proposed that gait transitions behave like bifurcations between attractors, with the relative phase of the leg segments as an order parameter and stride frequency and stride length as control parameters. In the present experiments, the authors tested the prediction that manipulation of the attractor layout, either through the addition of load to the ankles or through an increase in the grade of the treadmill, induces corresponding changes in the walk-run transition. As predicted, the load manipulation shifted the most stable walk and the transition to lower stride frequencies. In contrast, the grade manipulation shifted the most stable walk and the transition to shorter stride lengths. Other features of the dynamic theory were also replicated, including enhanced fluctuations of phase and systematic changes in stride length and frequency at the transition. Overall, in these experiments a shift of the attractors in control parameter space yielded a corresponding shift of the transition.

  18. DYNAMIC JOINT LOAD TRANSFER EFFICIENCY OF RIGID PAVEMENT

    Directory of Open Access Journals (Sweden)

    YU Xinhua

    2011-02-01

    Full Text Available the mechanistic analysis presented in this paper is only the beginning of new approach for understanding the real joint load transfer capability on airport and highway concrete pavements. It gives up the two major assumptions those have been popularly adopted by hundreds of published papers: the load is transferred under a wheel with zero speed and with fixed position. The real load transfer in field is always under wheels with non-zero speed and with varied position at any moment. The objective of this study focuses on quantifying the dynamic effects of a moving wheel while it is crossing a joint on a pavement. The analysis is conducted using a model of two-slab system on Kelvin foundation under a moving wheel with variable speed v, different pavement damping Cs, foundation reaction modulus k and foundation damping Ck. The dynamic joint load transfer efficiency is temporarily and empirically defined by the peak strain ratio LTE(S on the two sides of a joint. The primary findings include: (1 The higher speed of a moving wheel leads to the higher LTE(S;(2 The larger the pavement damping Cs leads to the higher LTE(S;(3 The numerical ratio c(=LTE(Sdynamic/ LTE(Sstatic varies in the range 1 to 2 mainly depending on speed v and damping Cs;(4 The LTE(Sdynamic is not sensitive to foundation reaction modulus k and foundation damping Ck. Further researches are needed for appropriate applications of the new model in practice.

  19. 云数据中心基于负载权重的负载均衡调度算法%Load Balancing Scheduling Algorithm Based on Load Weight for Cloud Data Center

    Institute of Scientific and Technical Information of China (English)

    杜吉成

    2013-01-01

    针对现有云数据中心的多维资源利用不均衡问题,提出基于资源负载权重的动态多资源负载均衡调度算法。算法结合服务器各维度资源动态负载情况,构造层次分析法(AHP)判断矩阵来处理多维资源对于负载均衡影响权重大小,在此基础上综合考虑任务资源需求,将任务放置到合适服务器来改善资源利用,实现资源间负载均衡。平台仿真显示新算法可有效提高利用率低的资源的利用效率,在提高整体资源利用率、降低资源间负载不均衡率方面有优势。%To solve the unbalance of multi-dimensional resource utilization in cloud data center, proposes a dynamic load balancing scheduling al-gorithm based on resource workload weight. By using Analytic Hierarchy Process (AHP) based on the dynamic resource utilization of servers to deal with multi-dimensional resources for load-balancing influence weights and consider the task resource requirements, places the right task to the appropriate server in order to improve resource utilization and implements the load-balancing between multi-dimensional resources. Platform emulation shows that the new algorithm can effectively improve the use efficiency especially for the resource which has a low utilization before, and has advantages in improving the overall resource utilization, reduces uneven rates for resource use.

  20. Dynamics and mass balance of Taylor Glacier, Antarctica: 3. State of mass balance

    Science.gov (United States)

    Kavanaugh, J. L.; Cuffey, K. M.; Morse, D. L.; Bliss, A. K.; Aciego, S. M.

    2009-11-01

    Taylor Glacier flows from the East Antarctic Ice Sheet and terminates in the McMurdo Dry Valleys, where it has left a geomorphologic record of past incursions. Here we use new data on the flow, thickness, and surface balance of Taylor Glacier to calculate ice fluxes and assess the current state of mass balance. Overall, the glacier is close to a state of zero net balance, and has largely adjusted to reduced snowfall on the Taylor Dome source region in the mid Holocene. One region of the upper ablation zone appears to be losing mass. Evidence from ice surface morphology and stable isotope profiles suggests that this mass loss is a long-term phenomenon, hence probably a lingering response to the earlier drying of Taylor Dome. Our data give a general indication of the size of ablation or accumulation changes needed for ice to advance far into Taylor Valley, as occurred 70 to 130 ka ago.

  1. The relationship between gait parameters and static and dynamic balance in the elderly

    OpenAIRE

    Razieh Tabe; VahidReza Borhaninejad; Yahya Sokhanguei; Heydar Sadeghi; Razieh Sadat Hossieni

    2015-01-01

    Background: The physiological changes and muscle problems can lead to balance disorder and increased risk of falling among the elderly. Therefore, it is necessary to evaluate the factors associated with balance in the elderly, to increase their awareness of the falling risks and to provide them with appropriate assistive devices.. Hence, this study was carried out to investigate the relationship between some gait parameters and static and dynamic balance in the elderly. Methods: In this qu...

  2. The Plasma Simulation Code: A modern particle-in-cell code with patch-based load-balancing

    Science.gov (United States)

    Germaschewski, Kai; Fox, William; Abbott, Stephen; Ahmadi, Narges; Maynard, Kristofor; Wang, Liang; Ruhl, Hartmut; Bhattacharjee, Amitava

    2016-08-01

    This work describes the Plasma Simulation Code (PSC), an explicit, electromagnetic particle-in-cell code with support for different order particle shape functions. We review the basic components of the particle-in-cell method as well as the computational architecture of the PSC code that allows support for modular algorithms and data structure in the code. We then describe and analyze in detail a distinguishing feature of PSC: patch-based load balancing using space-filling curves which is shown to lead to major efficiency gains over unbalanced methods and a previously used simpler balancing method.

  3. Dynamic performance of slender suspension footbridges under eccentric walking dynamic loads

    Science.gov (United States)

    Huang, Ming-Hui; Thambiratnam, David P.; Perera, Nimal J.

    2007-06-01

    This paper treats the vibration of slender suspension footbridges caused by eccentrically distributed walking dynamic loads. A suspension footbridge model with reverse profiled cables in both the vertical and horizontal planes was used in this conceptual study, while SAP2000 package is adopted in the numerical analysis. The dynamic behaviour of slender footbridges under walking dynamic loads is simulated by resonant vibration caused by synchronous excitations. It is found that slender suspension footbridges with shallow cable profiles often have coupled vibration modes such as coupled lateral-torsional or coupled torsional-lateral modes. When these coupled vibration modes are excited by walking pedestrians, excessive lateral vibration can be induced. Results also show that the effects of the reverse profiled cables on the dynamic performance in different vibration modes are complex. Reverse profiled cables in the horizontal plane can significantly suppress the lateral vibration in coupled lateral-torsional modes, but slightly increase the lateral vibration in coupled torsional-lateral modes.

  4. Dynamic load test of Arquin-designed CMU wall.

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Richard Pearson

    2010-02-01

    The Arquin Corporation has developed a new method of constructing CMU (concrete masonry unit) walls. This new method uses polymer spacers connected to steel wires that serve as reinforcing as well as a means of accurately placing the spacers so that the concrete block can be dry stacked. The hollows of the concrete block are then filled with grout. As part of a New Mexico Small Business Assistance Program (NMSBA), Sandia National Laboratories conducted a series of tests that dynamically loaded wall segments to compare the performance of walls constructed using the Arquin method to a more traditional method of constructing CMU walls. A total of four walls were built, two with traditional methods and two with the Arquin method. Two of the walls, one traditional and one Arquin, had every third cell filled with grout. The remaining two walls, one traditional and one Arquin, had every cell filled with grout. The walls were dynamically loaded with explosive forces. No significant difference was noted between the performance of the walls constructed by the Arquin method when compared to the walls constructed by the traditional method.

  5. Loads and Structural Dynamics Requirements for Spaceflight Hardware

    Science.gov (United States)

    Schultz, Kenneth P.

    2011-01-01

    The purpose of this document is to establish requirements relating to the loads and structural dynamics technical discipline for NASA and commercial spaceflight launch vehicle and spacecraft hardware. Requirements are defined for the development of structural design loads and recommendations regarding methodologies and practices for the conduct of load analyses are provided. As such, this document represents an implementation of NASA STD-5002. Requirements are also defined for structural mathematical model development and verification to ensure sufficient accuracy of predicted responses. Finally, requirements for model/data delivery and exchange are specified to facilitate interactions between Launch Vehicle Providers (LVPs), Spacecraft Providers (SCPs), and the NASA Technical Authority (TA) providing insight/oversight and serving in the Independent Verification and Validation role. In addition to the analysis-related requirements described above, a set of requirements are established concerning coupling phenomena or other interaction between structural dynamics and aerodynamic environments or control or propulsion system elements. Such requirements may reasonably be considered structure or control system design criteria, since good engineering practice dictates consideration of and/or elimination of the identified conditions in the development of those subsystems. The requirements are included here, however, to ensure that such considerations are captured in the design space for launch vehicles (LV), spacecraft (SC) and the Launch Abort Vehicle (LAV). The requirements in this document are focused on analyses to be performed to develop data needed to support structural verification. As described in JSC 65828, Structural Design Requirements and Factors of Safety for Spaceflight Hardware, implementation of the structural verification requirements is expected to be described in a Structural Verification Plan (SVP), which should describe the verification of each

  6. Comparison of Various Dynamic Balancing Principles Regarding Additional Mass and Additional Inertia

    NARCIS (Netherlands)

    Wijk, van der Volkert; Demeulenaere, Bram; Herder, Just L.

    2009-01-01

    The major disadvantage of existing dynamic balancing principles is that a considerable amount of mass and inertia is added to the system. The objectives of this article are to summarize, to compare, and to evaluate existing complete balancing principles regarding the addition of mass and the additio

  7. Dynamic balancing of a single crank-double slider mechanism with symmetrically moving couplers

    NARCIS (Netherlands)

    van der Wijk, V.; Herder, Justus Laurens; Pisla, Doina; Ceccarelli, Marco; Husty, Manfred; Corves, Burkhard

    2010-01-01

    This article presents a systematic investigation of the dynamic balancing of a singlecrank-double slider mechanism of which the coupler links have symmetric motion. From the equationsof the linear momentum and angular momentum the force balance conditions and momentbalance conditions are derived. Bo

  8. Study of regeneration system of 300 MW power unit based on nondeaerating heat balance diagram at reduced load

    Science.gov (United States)

    Esin, S. B.; Trifonov, N. N.; Sukhorukov, Yu. G.; Yurchenko, A. Yu.; Grigor'eva, E. B.; Snegin, I. P.; Zhivykh, D. A.; Medvedkin, A. V.; Ryabich, V. A.

    2015-09-01

    More than 30 power units of thermal power stations, based on the nondeaerating heat balance diagram, successfully operate in the former Soviet Union. Most of them are power units with a power of 300 MW, equipped with HTGZ and LMZ turbines. They operate according to a variable electric load curve characterized by deep reductions when undergoing night minimums. Additional extension of the range of power unit adjustment makes it possible to maintain the dispatch load curve and obtain profit for the electric power plant. The objective of this research is to carry out estimated and experimental processing of the operating regimes of the regeneration system of steam-turbine plants within the extended adjustment range and under the conditions when the constraints on the regeneration system and its equipment are removed. Constraints concerning the heat balance diagram that reduce the power unit efficiency when extending the adjustment range have been considered. Test results are presented for the nondeaerating heat balance diagram with the HTGZ turbine. Turbine pump and feed electric pump operation was studied at a power unit load of 120-300 MW. The reliability of feed pump operation is confirmed by a stable vibratory condition and the absence of cavitation noise and vibration at a frequency that characterizes the cavitation condition, as well as by oil temperature maintenance after bearings within normal limits. Cavitation performance of pumps in the studied range of their operation has been determined. Technical solutions are proposed on providing a profitable and stable operation of regeneration systems when extending the range of adjustment of power unit load. A nondeaerating diagram of high-pressure preheater (HPP) condensate discharge to the mixer. A regeneration system has been developed and studied on the operating power unit fitted with a deaeratorless thermal circuit of the system for removing the high-pressure preheater heating steam condensate to the mixer

  9. Development of a Dynamic Population Balance Plant Simulator for Mineral Processing Circuits

    National Research Council Canada - National Science Library

    Fatemeh Khoshnam; Mohammad reza Khalesi; Ahmad Khodadadi Darban; Mohammad Javad Zarei

    2015-01-01

    .... The dynamic simulator of each mentioned unit was also developedaccording to population balance models with the help of MATLAB/Simulink environment and wasverified against the data from the literature...

  10. ANALYSIS OF METHOD FOR DETERMINING AZIMUTH OF PRINCIPAL AXIS OF INERTIA BASED ON DYNAMIC BALANCE MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jun; GUAN Yingzi; QI Naiming

    2006-01-01

    The dynamic balance quality of a rotating object is an important factor to maintain the stability and accuracy for motion. The azimuth of the principal axis of inertia is a major sign of dynamic balance. A usual method is measuring moment of inertia matrix relative to some base coordinates on a rotary inertia machine so as to calculate the azimuth of principal axis of inertia. By using the measured unbalance results on the two trimmed planes on a vertical hard bearing double-plane dynamic balancing machine, the dimension and direction of couple unbalance can be found. An azimuth angle formula for the principal axis of inertia is derived and is solved by using unbalance quantities. The experiments indicate that method based on dynamic balancing measurement is proved rational and effective and has a fine precision.

  11. The effect of kinesiotape on dynamic balance following muscle fatigue in individuals with chronic ankle instability.

    Science.gov (United States)

    Kodesh, Einat; Dar, Gali

    2015-01-01

    This study aimed to evaluate the effect of kinesiotape (KT) on dynamic stability following ankle muscle fatigue among individuals with chronic ankle instability (CAI). Twenty participants with CAI participated in the study. Participants were tested under three conditions: KT, non-elastic tape, and no tape pre- and post-fatigue of the ankle muscles. Ankle muscles fatigue was induced using an isokinetic apparatus, activity of the fibularis muscle was recorded using one-channel vibromyography (VMG), and dynamic balance and neuromuscular control were assessed using the Y-Balance Test. Following fatigue exercises, the VMG signal significantly decreased in all groups (p < 0.01), without differences between groups. No significant difference in dynamic balance test scores was found between the pre- and post-fatigue condition for each group and between groups. Our results demonstrate that KT had no significant effects on dynamic balance and muscle activity following ankle muscle fatigue among individuals with CAI.

  12. Influence of loading pulse duration on dynamic load transfer in a simulated granular medium

    Science.gov (United States)

    Shukla, A.; Sadd, M. H.; Xu, Y.; Tai, Q. M.

    1993-11-01

    AN EXPERIMENTAL and numerical investigation was conducted to study the dynamic response of granular media when subjected to impact loadings with different periods or wavelengths. The granular medium was simulated by a one-dimensional assembly of circular disks arranged in a straight single chain. In the experimental study, the dynamic loading was produced using projectile impact from a gas gun onto one end of the granular assembly, and the measured wave signal was collected using strain gages. The numerical simulations were conducted using the distinct element method. It was found from the experiments and numerical simulations that input waves with a short period (τ ≈ 90 μs) will propagate in this granular medium with little waveform change under steady amplitude attenuation ; whereas longer waves (τ $̆200 μs) will propagate with significant waveform dispersion. For these longer wavelength signals, the smooth waveform will undergo separation into a series of short oscillatory signals, and this rearrangement of energy allows a portion of the transmitted signal to increase in amplitude during the initial phases of propagation. Thus the granular medium acts as a nonlinear wave guide, and local microstructure and contact nonlinearity will allow input signals of sufficiently long wavelength to excite resonant sub-units of the medium to produce this observed ringing separation. Following a modeling scheme originally proposed by NESTERENKO[J. Appl. Mech. Tech. Phys. 5,733 (1983)], a nonlinear wave equation model was developed which is related to soliton dynamics and leads to travelling wave solutions of specific wavelength found in our experimental and numerical studies.

  13. Relationship between maximum dynamic force of inferior members and body balance in strength training apprentices

    Directory of Open Access Journals (Sweden)

    Ariane Martins

    2010-08-01

    Full Text Available The relationship between force and balance show controversy results and has directimplications in exercise prescription practice. The objective was to investigate the relationshipbetween maximum dynamic force (MDF of inferior limbs and the static and dynamic balances.Participated in the study 60 individuals, with 18 to 24 years old, strength training apprentices.The MDF was available by mean the One Maximum Repetition (1MR in “leg press” and “kneeextension” and motor testes to available of static and dynamic balances. The correlation testsand multiple linear regression were applied. The force and balance variables showed correlationin females (p=0.038. The corporal mass and static balance showed correlation for the males(p=0.045. The explication capacity at MDF and practices time were small: 13% for staticbalance in males, 18% and 17%, respectively, for static and dynamic balance in females. Inconclusion: the MDF of inferior limbs showed low predictive capacity for performance in staticand dynamic balances, especially for males.

  14. Modeling and Performance Evaluation of Early Arrival Discrete Time Queueing System with Load Balancing Using Geometrical Distribution

    Directory of Open Access Journals (Sweden)

    Syed Asif AliShah

    2011-10-01

    Full Text Available Load balancing is an efficient technique used to maximize throughput, optimal resource utilization, minimized response time and avoiding congestion. This can be achieved by distributing the workload evenly across two or more network stations, nodes or buffers, links, central processing units, hard drives, or other resources. In this paper, we have modeled and developed a load balancing approach in a discrete-time domain to analyze and evaluate the system of finite network buffers using an early arrival system. Our approach of modeling such a system consists of two steps. The first step is the determination of all system-state stages and their corresponding transition probabilities. Next, we compute various performance measures by utilizing the system state transition probabilities for its steady-state behavior.

  15. Principle and Realization of Load Balancing%应用负载均衡技术原理与实现

    Institute of Scientific and Technical Information of China (English)

    梅琨; 余慧

    2014-01-01

    Load balancing technique contributes good usability and security to application delivery. This paper presents not only the principle of load balancing technique, but also its realization in detail. Further, prospective application of this technique and fu-ture research work are also discussed.%应用负载均衡技术在应用交付方面具有良好的可用性和安全性。本文详细讲解了应用负载均衡技术的原理及实现算法,并就下一步新型应用负载均衡技术的发展方向进行了展望。

  16. IDENTIFYING NETWORK LOAD BALANCING REQUIREMENTS ON HISTORICAL TRAFFIC FLOW USING MACHINE LEARNING APPROACH FOR FLEXIBLE MULTIPATH NETWORKS

    Directory of Open Access Journals (Sweden)

    K BALAMURUGAN

    2010-08-01

    Full Text Available Multipath routing uses several paths to distribute traffic from a source to destination. This not only improves network performance but also achieves load balancing and fault tolerance. Though multipath routing is not deployed widely in the internet, current systems chooses the paths with the same lowest cost to the destination and the same administrative distance.In this paper we propose a flexible multipath network wherein multipath routing algorithm is invoked when the quality of service is affected. Our proposal provides a method to gradually shift from a single path existing network to a reliable multipath network in the future.We have used machine learning approach to identify the instance when network load balancing is required with good results.

  17. An HIV epidemic model based on viral load dynamics: value in assessing empirical trends in HIV virulence and community viral load.

    Science.gov (United States)

    Herbeck, Joshua T; Mittler, John E; Gottlieb, Geoffrey S; Mullins, James I

    2014-06-01

    Trends in HIV virulence have been monitored since the start of the AIDS pandemic, as studying HIV virulence informs our understanding of HIV epidemiology and pathogenesis. Here, we model changes in HIV virulence as a strictly evolutionary process, using set point viral load (SPVL) as a proxy, to make inferences about empirical SPVL trends from longitudinal HIV cohorts. We develop an agent-based epidemic model based on HIV viral load dynamics. The model contains functions for viral load and transmission, SPVL and disease progression, viral load trajectories in multiple stages of infection, and the heritability of SPVL across transmissions. We find that HIV virulence evolves to an intermediate level that balances infectiousness with longer infected lifespans, resulting in an optimal SPVL∼4.75 log10 viral RNA copies/mL. Adaptive viral evolution may explain observed HIV virulence trends: our model produces SPVL trends with magnitudes that are broadly similar to empirical trends. With regard to variation among studies in empirical SPVL trends, results from our model suggest that variation may be explained by the specific epidemic context, e.g. the mean SPVL of the founding lineage or the age of the epidemic; or improvements in HIV screening and diagnosis that results in sampling biases. We also use our model to examine trends in community viral load, a population-level measure of HIV viral load that is thought to reflect a population's overall transmission potential. We find that community viral load evolves in association with SPVL, in the absence of prevention programs such as antiretroviral therapy, and that the mean community viral load is not necessarily a strong predictor of HIV incidence.

  18. An HIV epidemic model based on viral load dynamics: value in assessing empirical trends in HIV virulence and community viral load.

    Directory of Open Access Journals (Sweden)

    Joshua T Herbeck

    2014-06-01

    Full Text Available Trends in HIV virulence have been monitored since the start of the AIDS pandemic, as studying HIV virulence informs our understanding of HIV epidemiology and pathogenesis. Here, we model changes in HIV virulence as a strictly evolutionary process, using set point viral load (SPVL as a proxy, to make inferences about empirical SPVL trends from longitudinal HIV cohorts. We develop an agent-based epidemic model based on HIV viral load dynamics. The model contains functions for viral load and transmission, SPVL and disease progression, viral load trajectories in multiple stages of infection, and the heritability of SPVL across transmissions. We find that HIV virulence evolves to an intermediate level that balances infectiousness with longer infected lifespans, resulting in an optimal SPVL∼4.75 log10 viral RNA copies/mL. Adaptive viral evolution may explain observed HIV virulence trends: our model produces SPVL trends with magnitudes that are broadly similar to empirical trends. With regard to variation among studies in empirical SPVL trends, results from our model suggest that variation may be explained by the specific epidemic context, e.g. the mean SPVL of the founding lineage or the age of the epidemic; or improvements in HIV screening and diagnosis that results in sampling biases. We also use our model to examine trends in community viral load, a population-level measure of HIV viral load that is thought to reflect a population's overall transmission potential. We find that community viral load evolves in association with SPVL, in the absence of prevention programs such as antiretroviral therapy, and that the mean community viral load is not necessarily a strong predictor of HIV incidence.

  19. Dynamic Response of Inextensible Beams by Improved Energy Balance Method

    DEFF Research Database (Denmark)

    Sfahani, M. G.; Barari, Amin; Omidvar, M.

    2011-01-01

    An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam...

  20. A Performance Comparison of Stability, Load-Balancing and Power-Aware Routing Protocols for Mobile Ad Hoc Networks

    CERN Document Server

    Meghanathan, Natarajan

    2010-01-01

    The high-level contribution of this paper is a simulation-based detailed performance comparison of three different classes of routing protocols for mobile ad hoc networks: stability-based routing, power-aware routing and load-balanced routing. We choose the Flow-Oriented Routing protocol (FORP), the traffic interference based Load Balancing Routing (LBR) protocol and Min-Max Battery Cost Routing (MMBCR) as representatives of the stability-based routing, load-balancing and power-aware routing protocols respectively. Among the three routing protocols, FORP incurs the least number of route transitions; while LBR incurs the smallest hop count and lowest end-to-end delay per data packet. Energy consumed per node is the least for MMBCR, closely followed by LBR. MMBCR is the most fair in terms of node usage and hence it incurs the largest time for first node failure. FORP tends to repeatedly use nodes lying on the stable path and hence is the most unfair of the three routing protocols and it incurs the smallest valu...

  1. Exploring the dynamics of balance data - movement variability in terms of drift and diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Gottschall, Julia [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)], E-mail: julia.gottschall@uni-oldenburg.de; Peinke, Joachim [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)], E-mail: peinke@uni-oldenburg.de; Lippens, Volker [Department of Human Movement, University of Hamburg, Moller Street 10, D-20148 Hamburg (Germany)], E-mail: vlippens@uni-hamburg.de; Nagel, Volker [Department of Human Movement, University of Hamburg, Moller Street 10, D-20148 Hamburg (Germany)

    2009-02-23

    We introduce a method to analyze postural control on a balance board by reconstructing the underlying dynamics in terms of a Langevin model. Drift and diffusion coefficients are directly estimated from the data and fitted by a suitable parametrization. The governing parameters are utilized to evaluate balance performance and the impact of supra-postural tasks on it. We show that the proposed method of analysis gives not only self-consistent results but also provides a plausible model for the reconstruction of balance dynamics.

  2. Exploring the dynamics of balance data — movement variability in terms of drift and diffusion

    Science.gov (United States)

    Gottschall, Julia; Peinke, Joachim; Lippens, Volker; Nagel, Volker

    2009-02-01

    We introduce a method to analyze postural control on a balance board by reconstructing the underlying dynamics in terms of a Langevin model. Drift and diffusion coefficients are directly estimated from the data and fitted by a suitable parametrization. The governing parameters are utilized to evaluate balance performance and the impact of supra-postural tasks on it. We show that the proposed method of analysis gives not only self-consistent results but also provides a plausible model for the reconstruction of balance dynamics.

  3. The impact of Wii Fit intervention on dynamic balance control in children with probable Developmental Coordination Disorder and balance problems.

    Science.gov (United States)

    Jelsma, Dorothee; Geuze, Reint H; Mombarg, Remo; Smits-Engelsman, Bouwien C M

    2014-02-01

    The aim of this study was to examine differences in the performance of children with probable Developmental Coordination Disorder (p-DCD) and balance problems (BP) and typical developing children (TD) on a Wii Fit task and to measure the effect on balance skills after a Wii Fit intervention. Twenty-eight children with BP and 20 TD-children participated in the study. Motor performance was assessed with the Movement Assessment Battery for Children (MABC2), three subtests of the Bruininks Oseretsky Test (BOT2): Bilateral Coordination, Balance and Running Speed & Agility, and a Wii Fit ski slalom test. The TD children and half of the children in the BP group were tested before and after a 6weeks non-intervention period. All children with BP received 6weeks of Wii Fit intervention (with games other than the ski game) and were tested before and afterwards. Children with BP were less proficient than TD children in playing the Wii Fit ski slalom game. Training with the Wii Fit improved their motor performance. The improvement was significantly larger after intervention than after a period of non-intervention. Therefore the change cannot solely be attributed to spontaneous development or test-retest effect. Nearly all children enjoyed participation during the 6weeks of intervention. Our study shows that Wii Fit intervention is effective and is potentially a method to support treatment of (dynamic) balance control problems in children.

  4. Dynamics and mechanics of bed-load tracer particles

    Directory of Open Access Journals (Sweden)

    C. B. Phillips

    2014-12-01

    Full Text Available Understanding the mechanics of bed load at the flood scale is necessary to link hydrology to landscape evolution. Here we report on observations of the transport of coarse sediment tracer particles in a cobble-bedded alluvial river and a step-pool bedrock tributary, at the individual flood and multi-annual timescales. Tracer particle data for each survey are composed of measured displacement lengths for individual particles, and the number of tagged particles mobilized. For single floods we find that measured tracer particle displacement lengths are exponentially distributed; the number of mobile particles increases linearly with peak flood Shields stress, indicating partial bed load transport for all observed floods; and modal displacement distances scale linearly with excess shear velocity. These findings provide quantitative field support for a recently proposed modeling framework based on momentum conservation at the grain scale. Tracer displacement is weakly negatively correlated with particle size at the individual flood scale; however cumulative travel distance begins to show a stronger inverse relation to grain size when measured over many transport events. The observed spatial sorting of tracers approaches that of the river bed, and is consistent with size-selective deposition models and laboratory experiments. Tracer displacement data for the bedrock and alluvial channels collapse onto a single curve – despite more than an order of magnitude difference in channel slope – when variations of critical Shields stress and flow resistance between the two are accounted for. Results show how bed load dynamics may be predicted from a record of river stage, providing a direct link between climate and sediment transport.

  5. A dynamic human water and electrolyte balance model for verification and optimization of life support systems in space flight applications

    Science.gov (United States)

    Hager, P.; Czupalla, M.; Walter, U.

    2010-11-01

    In this paper we report on the development of a dynamic MATLAB SIMULINK® model for the water and electrolyte balance inside the human body. This model is part of an environmentally sensitive dynamic human model for the optimization and verification of environmental control and life support systems (ECLSS) in space flight applications. An ECLSS provides all vital supplies for supporting human life on board a spacecraft. As human space flight today focuses on medium- to long-term missions, the strategy in ECLSS is shifting to closed loop systems. For these systems the dynamic stability and function over long duration are essential. However, the only evaluation and rating methods for ECLSS up to now are either expensive trial and error breadboarding strategies or static and semi-dynamic simulations. In order to overcome this mismatch the Exploration Group at Technische Universität München (TUM) is developing a dynamic environmental simulation, the "Virtual Habitat" (V-HAB). The central element of this simulation is the dynamic and environmentally sensitive human model. The water subsystem simulation of the human model discussed in this paper is of vital importance for the efficiency of possible ECLSS optimizations, as an over- or under-scaled water subsystem would have an adverse effect on the overall mass budget. On the other hand water has a pivotal role in the human organism. Water accounts for about 60% of the total body mass and is educt and product of numerous metabolic reactions. It is a transport medium for solutes and, due to its high evaporation enthalpy, provides the most potent medium for heat load dissipation. In a system engineering approach the human water balance was worked out by simulating the human body's subsystems and their interactions. The body fluids were assumed to reside in three compartments: blood plasma, interstitial fluid and intracellular fluid. In addition, the active and passive transport of water and solutes between those

  6. Biomechanical Dynamics of Cranial Sutures during Simulated Impulsive Loading

    Directory of Open Access Journals (Sweden)

    Z. Q. Zhang

    2015-01-01

    Full Text Available Background. Cranial sutures are deformable joints between the bones of the skull, bridged by collagen fibres. They function to hold the bones of the skull together while allowing for mechanical stress transmission and deformation. Objective. The aim of this study is to investigate how cranial suture morphology, suture material property, and the arrangement of sutural collagen fibres influence the dynamic responses of the suture and surrounding bone under impulsive loads. Methods. An idealized bone-suture-bone complex was analyzed using a two-dimensional finite element model. A uniform impulsive loading was applied to the complex. Outcome variables of von Mises stress and strain energy were evaluated to characterize the sutures’ biomechanical behavior. Results. Parametric studies revealed that the suture strain energy and the patterns of Mises stress in both the suture and surrounding bone were strongly dependent on the suture morphologies. Conclusions. It was concluded that the higher order hierarchical suture morphology, lower suture elastic modulus, and the better collagen fiber orientation must benefit the stress attenuation and energy absorption.

  7. DECREASING OF MECHANISMS DYNAMIC LOADING AT THE TRANSIENT STATE

    Directory of Open Access Journals (Sweden)

    V. S. Loveikin

    2015-11-01

    Full Text Available Purpose. It is necessary to select modes of motion to reduce the dynamic loads in the mechanisms. This choice should be made on optimization basis. The purpose of research is to study methods of synthesis regimes of mechanisms and machines motion that provide optimal modes of movement for terminal and integral criteria. Methodology. For research the one-mass dynamic model of the mechanism has been used. As optimization criteria the terminal and comprehensive integral criteria were used. The stated optimization problem has been solved using dynamic programming and variational calculation. The direct variation method, which allowed finding only approximate solution of the original problem of optimal control, has been used as well. Findings. The ways of ensuring the absolute minimum of terminal criterion have been set for each method of problem solving. The stated characteristics show softness changes of kinematic functions during braking of mechanism. They point to the absolute minimum of adopted terminal criterion in the calculation. Originality. It is necessary to introduce new variables in the system equations during the solving of optimal control problems using dynamic programming to achieve an absolute minimum of terminal criteria. In general, to achieve a minimum of n-order terminal criterion an optimization problem should find relatively (n+1-th order function. When optimization problems is solving by variational calculation in order to ensure a minimization of n-th order terminal criterion by selecting the appropriate boundary conditions, it is necessary to solve the Euler-Poisson 2(n+1-th order equation (subject to symmetric setting boundary conditions. It is a necessary condition for an extremum of the functional with the (n+1-th order integrant. Practical value. Minimizing of adopted terminal criterion in the calculation allows eliminate the brunt in kinematic gearing of mechanisms, which increases their operational life. In addition

  8. Dynamic Response of Inextensible Beams by Improved Energy Balance Method

    DEFF Research Database (Denmark)

    Sfahani, M. G.; Barari, Amin; Omidvar, M.

    2011-01-01

    An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam with a rotationa......An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam...... procedure for a particular value of the initial condition is then used to estimate the constants. This semi-analytical representation gives excellent approximations to the exact solutions for the whole range of the oscillation amplitude, reducing the respective error of angular frequency in comparison...

  9. Departures from Axisymmetric Balance Dynamics during Secondary Eyewall Formation

    Science.gov (United States)

    2014-10-01

    arguments, based mostly on linearized Ekman theory, to propose a feedback mechanism for secondary eye- wall formation that involves a local enhancement of...the radial vorticity gradient, frictional updraft, and con- vection. The hypothesized feedback, based primarily on linear Ekman balance reasoning, has...largely to a vertical column within an annular region about 15 km wide, centered around 40 km and sloping outward. The mean heating rate maximum exhibits a

  10. Electrical Power Grid Delivery Dynamic Analysis: Using Prime Mover Engines to Balance Dynamic Wind Turbine Output

    Energy Technology Data Exchange (ETDEWEB)

    Diana K. Grauer; Michael E. Reed

    2011-11-01

    This paper presents an investigation into integrated wind + combustion engine high penetration electrical generation systems. Renewable generation systems are now a reality of electrical transmission. Unfortunately, many of these renewable energy supplies are stochastic and highly dynamic. Conversely, the existing national grid has been designed for steady state operation. The research team has developed an algorithm to investigate the feasibility and relative capability of a reciprocating internal combustion engine to directly integrate with wind generation in a tightly coupled Hybrid Energy System. Utilizing the Idaho National Laboratory developed Phoenix Model Integration Platform, the research team has coupled demand data with wind turbine generation data and the Aspen Custom Modeler reciprocating engine electrical generator model to investigate the capability of reciprocating engine electrical generation to balance stochastic renewable energy.

  11. Adaptive load balancing scheme in ad hoc networks%Ad hoc网络中一种自适应的负载均衡机制

    Institute of Scientific and Technical Information of China (English)

    袁玉华; 陈惠民; 贾旻

    2007-01-01

    An adaptive load balancing scheme is proposed to balance the load in ad hoc networks.The new scheme can be applied in most on-demand routing protocols resulting in significant performance improvement.The proposed scheme is applied to the ad hoc on-demand distance vector(AODV)routing protocol.Simulation results show that the network load is balanced on the whole,and performance in packet loss rate,routing overhead and average end-to-end delay is also improved.

  12. Dynamic Loads Due to Synchronized Movements of People

    DEFF Research Database (Denmark)

    Hansen, S.O.; Sørensen, John Dalsgaard

    2002-01-01

    , and the paper focus on the load harmonics determining the load effects o f synchronized movements. The Jack of load correlation is determined by correlation coefficients, which are specified as fimetion o f the load harmonic considered. The model is calibrated to measured data and simplified procedures...

  13. Comparison of static and dynamic balance among collegiate cricket, soccer and volleyball male players

    Directory of Open Access Journals (Sweden)

    P Ratan Khuman

    2014-01-01

    Full Text Available Background: Athletes from different sports requires balance control for their better performance depending on game type they involved. When prescribing balance exercises to athletes in different sports, it may be important to recognize performance variations. Objective: The objective of the present study was to compare the static and dynamic balance among collegiate cricket, soccer and volleyball male players. Materials and Methods: A total of 150 students, college level male players from five different colleges were requited for the study with purposive sampling. They were assigned into three different groups according to their types of sports, cricket n = 50, soccer n = 50, volleyball n = 50. The static and dynamic balance was assessed using flamingo balance test (FBT and star excursion balance test (SEBT in institutional based sports physiotherapy department. Results: Intra-group comparison for FBT and SEBT score shows no significance difference (P > 0.05. Multiple comparison of FBT and SEBT score between groups reveals significantly difference between cricket and soccer player (P = 0.000, between cricket and volleyball player (P = 0.000 and between soccer player and volleyball players (P = 0.000. FBT and SEBT score were significantly higher in soccer players than volleyball and cricketer were found to have the least score compared with soccer and volleyball players. Conclusion: There is significance difference in static and dynamic balance among collegiate cricket, soccer and volleyball male players. The soccer players demonstrate higher balance than volleyball players and the volleyball players have a higher balance than that of cricketers both statically and dynamically.

  14. Are Eyewall Replacement Cycles Governed Largely by Axisymmetric Balance Dynamics?

    Science.gov (United States)

    2015-01-01

    dynamics of convective rings [as artic- ulated by Willoughby et al. (1982) and Shapiro and Willoughby (1982)]. This view has been explicitly and...implicitly expressed in published papers (e.g., Willoughby 1988, 1990; Rozoff et al. 2008; Kepert 2010, 2013). As an example, in his insightful review paper...entitled ‘‘The dynamics of the tropical cyclone core,’’ Willoughby (1988, his ‘‘Summary’’ section) described the mechanism of eyewall contraction as

  15. Nonlinear dynamics modeling and simulation of two-wheeled self-balancing vehicle

    Directory of Open Access Journals (Sweden)

    Yunping Liu

    2016-11-01

    Full Text Available Two-wheeled self-balancing vehicle system is a kind of naturally unstable underactuated system with high-rank unstable multivariable strongly coupling complicated dynamic nonlinear property. Nonlinear dynamics modeling and simulation, as a basis of two-wheeled self-balancing vehicle dynamics research, has the guiding effect for system design of the project demonstration and design phase. Dynamics model of the two-wheeled self-balancing vehicle is established by importing a TSi ProPac package to the Mathematica software (version 8.0, which analyzes the stability and calculates the Lyapunov exponents of the system. The relationship between external force and stability of the system is analyzed by the phase trajectory. Proportional–integral–derivative control is added to the system in order to improve the stability of the two-wheeled self-balancing vehicle. From the research, Lyapunov exponent can be used to research the stability of hyperchaos system. The stability of the two-wheeled self-balancing vehicle is better by inputting the proportional–integral–derivative control. The Lyapunov exponent and phase trajectory can help us analyze the stability of a system better and lay the foundation for the analysis and control of the two-wheeled self-balancing vehicle system.

  16. Integration of part selection, machine loading and machining optimisation decisions for balanced workload in flexible manufacturing system

    Directory of Open Access Journals (Sweden)

    Mussa I. Mgwatu

    2011-10-01

    Full Text Available This paper demonstrates the importance of incorporating and solving the machining optimisation problem jointly with part selection and machine loading problems in order to avoid unbalanced workload in the FMS. Unbalanced workload renders to ineffective FMS such that some machines on the manufacturing shop floor become more occupied than others. Since CNC machine tools employed in the FMS are rather expensive, it is mostly important to balance the workload so that all machines can be effectively utilised. Therefore, in this study, two mathematical models are presented and solved in efforts to balance the workload and improve the performance of the FMS. A two-stage sequential approach is adopted whereby the first stage deals with the maximum throughput objective while the second stage deals with the minimum production cost objective. The results show that when part selection, machine loading and machining optimisation problems are jointly solved, more practical decisions can be made and a wide range of balanced workload in the FMS can be realised with minimum production cost objective. The results also show that the available machine time and tooling budget have enormous effects on throughput and production cost.

  17. Testing Studies on Rock Failure Modes of Statically Loads Under Dynamic Loading

    Institute of Scientific and Technical Information of China (English)

    YE Zhouyuan; LI Xibing; LIU Xiling; MA Chunde; YIN Tubing

    2008-01-01

    By means of the improved split Hopkionson pressure bar(SHPB) with axial pre-pressure and confined pressure,two series of experiments on sandstone are earned out to research the failure mode of rock during the course of exploitation of resources in deep.One is under the conditions that the confining pressure is fixed and the axial pressure is changeable.The other is under the conditions that the confining pressure becomes and the axial pressure is fixed.It is found that samples break up evenly after impacting when axial static pressures are low,there is great disparity in size of fragments when axial static pressures are high,and the main bodies of samples after the tests under the combination of dynamic and static loads frequently show the type of V or X.The samples are more close-grained at the elastic stage and impacts make many cracks be generated and developed,as makes samples more crackable.At the initial phase of damage stage,the static pressures make some cracks in the samples which are undeveloped and the impacts' role is similar to that at the elastic stage.At the metaphase or anaphase of damage stage,these cracks in the samples develop adequately and the impacts mainly accelerate samples' failure.The main bodies of samples show the type of V or X after impacting due to the confining pressures' restraining samples' lateral formation at the elastic stage or the initial phase of damage stage,the main bodies of samples have almost formed at the stage loading static pressures and the results after impacting usually are similar to those under the axial pressures tests.

  18. Self-Organized Criticality in Small-World Networks Based on the Social Balance Dynamics

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-Kuan

    2011-01-01

    A node model is proposed to study the self-organized criticality in the small-world networks which represent the social networks. Based on the node model and the social balance dynamics, the social networks are mapped to the thermodynamic systems and the phenomena are studied with physical methods. It is found that the avalanche in the small-world networks at the critical state satisfies the power-law distribution spatially and temporally.%A node model is proposed to study the self-organized criticality in the small-world networks which represent the social networks.Based on the node model and the social balance dynamics,the social networks are mapped to the thermodynamic systems and the phenomena are studied with physical methods.It is found that the avalanche in the small-world networks at the critical state satisfies the power-law distribution spatially and temporally.The balance dynamics on social networks[1] based on the notion of social balance has been studied.[2-4]In Ref.[2],the authors studied the triad balance dynamic on a completely connected network representing a social network.At each step,they choose a triad relation from the social network and let it evolve.When the network gets dynamically balanced,they will reach the distributions of each triad relation.Moreover,other researchers subsequently carried out several studies on balance dynamics.[5,6]In this Letter,a node model is proposed to describe the triad relations,so the edge relations in Ref.[2] are changed to node relations,which may be more a universal method to study the phenomena in social networks.We will introduce the node model later.

  19. Dynamical models explaining social balance and evolution of cooperation.

    Science.gov (United States)

    Traag, Vincent Antonio; Van Dooren, Paul; De Leenheer, Patrick

    2013-01-01

    Social networks with positive and negative links often split into two antagonistic factions. Examples of such a split abound: revolutionaries versus an old regime, Republicans versus Democrats, Axis versus Allies during the second world war, or the Western versus the Eastern bloc during the Cold War. Although this structure, known as social balance, is well understood, it is not clear how such factions emerge. An earlier model could explain the formation of such factions if reputations were assumed to be symmetric. We show this is not the case for non-symmetric reputations, and propose an alternative model which (almost) always leads to social balance, thereby explaining the tendency of social networks to split into two factions. In addition, the alternative model may lead to cooperation when faced with defectors, contrary to the earlier model. The difference between the two models may be understood in terms of the underlying gossiping mechanism: whereas the earlier model assumed that an individual adjusts his opinion about somebody by gossiping about that person with everybody in the network, we assume instead that the individual gossips with that person about everybody. It turns out that the alternative model is able to lead to cooperative behaviour, unlike the previous model.

  20. Microworlds of the dynamic balanced scorecard for university (DBSC-UNI)

    Science.gov (United States)

    Hawari, Nurul Nazihah; Tahar, Razman Mat

    2015-12-01

    This research focuses on the development of a Microworlds of the dynamic balanced scorecard for university in order to enhance the university strategic planning process. To develop the model, we integrated both the balanced scorecard method and the system dynamics modelling method. Contrasting the traditional university planning tools, the developed model addresses university management problems holistically and dynamically. It is found that using system dynamics modelling method, the cause-and-effect relationships among variables related to the four conventional balanced scorecard perspectives are better understand. The dynamic processes that give rise to performance differences between targeted and actual performances also could be better understood. So, it is expected that the quality of the decisions taken are improved because of being better informed. The developed Microworlds can be exploited by university management to design policies that can positively influence the future in the direction of desired goals, and will have minimal side effects. This paper integrates balanced scorecard and system dynamics modelling methods in analyzing university performance. Therefore, this paper demonstrates the effectiveness and strength of system dynamics modelling method in solving problem in strategic planning area particularly in higher education sector.

  1. Toe functions have little effect on dynamic balance ability in elderly people.

    Science.gov (United States)

    Yoshimoto, Yoshinobu; Oyama, Yukitsuna; Tanaka, Mamoru; Sakamoto, Asuka

    2017-01-01

    [Purpose] The purpose of this study was to examine the toe function of elderly people and the association with the dynamic balance ability for the developing effective fall-prevention measures. [Subjects and Methods] Seventy-eight participants in a community health service were included in this cross-sectional study. The Timed Up and Go Test and Four Square Step Test were used to test dynamic balance ability. The toe functions related to dynamic balance ability were toe flexion strength, presence or absence of restricted range of motion of the hallux, presence or absence of hallux pain, and hallux valgus angle. [Results] Factors related to the Timed Up and Go Test results were toe flexion strength, age, and presence or absence of hallux pain. Their standard partial regression coefficients were -0.400, 0.277, and -0.218, respectively. Factors related to the Four Square Step Test results were toe flexion strength and age. Their standard partial regression coefficients were -0.334 and 0.277, respectively. [Conclusion] Toe functions appear to have little impact on dynamic balance ability in elderly people who have mild toe dysfunction. Approaches that address not only the toes, but trunk functions, and other leg joints should be investigated for improving the dynamic balance ability.

  2. A Reliable Routing Protocol for WSN Based on Load Balancing%一种基于负载均衡的WSN可靠路由协议

    Institute of Scientific and Technical Information of China (English)

    李宗海; 柳少军; 王燕; 牛晓光

    2013-01-01

    The communication qualities of the wireless links between the neighbor nodes are poor and unstable which may be caused by node energy exhaustion, node physical destroy or environment inference. The invalidation of wireless links can cause the route breakdown, packet loss and retransmission, which weaken the reliability of the data transmission. Numerous studies show the difficulty to improve the energy efficiency and reliability of routing protocols due to the local unbalanced traffic load distribution. This paper proposes a reliable routing protocol based on load-balancing, namely RR. This protocol employs some mechanisms, including continuous gradient parameter and dynamic link quality evaluation. Experimental results show that this protocol achieves better performance in energy consumption, load balancing and delivery rate.%根据传感器网络的无线信道质量及稳定性、网络局部区域负载均衡性等特点,提出一个跨层协作的可靠路由协议(RR),包括链路质量动态评估机制、节点间距离的精确分级评估方法。RR可以建立并维护从传感器节点到汇聚节点的传输路径,将监测数据可靠地传输到汇聚节点。实验结果表明,在基于 RR 的传感器网络中,该协议可有效地减少靠近汇聚节点区域节点的最高负载,并提高数据接收率。

  3. CORRELATION OF ANKLE DORSIFLEXION RANGE OF MOTION WITH DYNAMIC BALANCE IN YOUNG NORMAL INDIVIDUALS

    Directory of Open Access Journals (Sweden)

    Pranali Suryavanshi

    2015-08-01

    Full Text Available This study was to examine correlation of ankle dorsiflexion range of motion with dynamic balance in young normal individuals. A cross sectional study has been done on 60 females by convenient sampling. The study was to examine dorsiflexion ROM by using star excursion balance test. It was performed in all directions for three trials. Distance was recorded with measure tape. Ankle ROM was performed by weight bearing lunge. Individuals who demonstrate impairments in dorsiflexion ROM may also demonstrate difficulty with portions of the SEBT. There is significant positive correlation in between dorsiflexion range of motion and star excursion balance test in anterior and postero lateral direction.

  4. An evaluation of spindle-shaft seizure accident sequences for the Schenck Dynamic Balancer

    Energy Technology Data Exchange (ETDEWEB)

    Bott, T.F.; Fischer, S.R.

    1998-11-01

    This study was conducted at the request of the USDOE/AL Dynamic Balancer Project Team to develop a set of representative accident sequences initiated by rapid seizure of the spindle shaft of the Schenck dynamic balancing machine used in the mass properties testing activities in Bay 12-60 at the Pantex Plant. This Balancer is used for balancing reentry vehicles. In addition, the study identified potential causes of possible spindle-shaft seizure leading to a rapid deceleration of the rotating assembly. These accident sequences extend to the point that the reentry vehicle either remains in stable condition on the balancing machine or leaves the machine with some translational and rotational motion. Fault-tree analysis was used to identify possible causes of spindle-shaft seizure, and failure modes and effects analysis identified the results of shearing of different machine components. Cause-consequence diagrams were used to help develop accident sequences resulting from the possible effects of spindle-shaft seizure. To make these accident sequences physically reasonable, the analysts used idealized models of the dynamics of rotating masses. Idealized physical modeling also was used to provide approximate values of accident parameters that lead to branching down different accident progression paths. The exacerbating conditions of balancing machine over-speed and improper assembly of the fixture to the face plate are also addressed.

  5. An evaluation of spindle-shaft seizure accident sequences for the Schenck Dynamic Balancer

    Energy Technology Data Exchange (ETDEWEB)

    Bott, T.F.; Fischer, S.R.

    1998-11-01

    This study was conducted at the request of the USDOE/AL Dynamic Balancer Project Team to develop a set of representative accident sequences initiated by rapid seizure of the spindle shaft of the Schenck dynamic balancing machine used in the mass properties testing activities in Bay 12-60 at the Pantex Plant. This Balancer is used for balancing reentry vehicles. In addition, the study identified potential causes of possible spindle-shaft seizure leading to a rapid deceleration of the rotating assembly. These accident sequences extend to the point that the reentry vehicle either remains in stable condition on the balancing machine or leaves the machine with some translational and rotational motion. Fault-tree analysis was used to identify possible causes of spindle-shaft seizure, and failure modes and effects analysis identified the results of shearing of different machine components. Cause-consequence diagrams were used to help develop accident sequences resulting from the possible effects of spindle-shaft seizure. To make these accident sequences physically reasonable, the analysts used idealized models of the dynamics of rotating masses. Idealized physical modeling also was used to provide approximate values of accident parameters that lead to branching down different accident progression paths. The exacerbating conditions of balancing machine over-speed and improper assembly of the fixture to the face plate are also addressed.

  6. Effects of moving dynamic tyre loads on tyre-pavement contact stresses

    CSIR Research Space (South Africa)

    Steyn, WJvdM

    2002-01-01

    Full Text Available The purpose of this paper is to indicate the effect that moving dynamic tyre loads has on the tyre-pavement contact stresses used in pavement analysis. Traditionally tyre loads (in pavement analysis) are modelled as constant loads applied through...

  7. Dynamic Analysis of Wind Turbine Planetary Gears Using an Extended Harmonic Balance Approach: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Keller, J.; Parker, R. G.

    2012-06-01

    The dynamics of wind turbine planetary gears with gravity effects are investigated using an extended harmonic balance method that extends established harmonic balance formulations to include simultaneous internal and external excitations. The extended harmonic balance method with arc-length continuation and Floquet theory is applied to a lumped-parameter planetary gear model including gravity, fluctuating mesh stiffness, bearing clearance, and nonlinear tooth contact to obtain the planetary gear dynamic response. The calculated responses compare well with time domain integrated mathematical models and experimental results. Gravity is a fundamental vibration source in wind turbine planetary gears and plays an important role in system dynamics, causing hardening effects induced by tooth wedging and bearing-raceway contacts. Bearing clearance significantly reduces the lowest resonant frequencies of translational modes. Gravity and bearing clearance together lowers the speed at which tooth wedging occurs lower than the resonant frequency.

  8. The Application of Ridge Regression in Dynamic Balancing of Flexible Rotors Based on Influence Coefficient Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the model structure of the influence coefficient method analyzed in depth by matrix theory,it is explained the reason why the unreasonable and instable correction masses with bigger MSE are obtained by LS influence coefficient method when there are correlation planes in the dynamic balancing. It also presened the new ridge regression method for solving correction masses according to the Tikhonov regularization theory, and described the reason why the ridge regression can eliminate the disadvantage of the LS method. Applying this new method to dynamic balancing of gas turbine, it is found that this method is superior to the LS method when influence coefficient matrix is ill-conditioned,the minimal correction masses and residual vibration are obtained in the dynamic balancing of rotors.

  9. Dynamic Behaviour of Concrete Sandwich Panel under Blast Loading

    Directory of Open Access Journals (Sweden)

    Dong Yongxiang

    2009-01-01

    Full Text Available Surface contact explosion experiments were performed to study the dynamic behaviour of concrete sandwich panel subjected to blast loading. Experimental results have shown that there are four damage modes explosion cratering, scabbing of the backside, radial cracking induced failure, and circumferential cracking induced failure. It also illustrates that different foam materials sandwiched in the multi-layered medium have an important effect on damage patterns. Due to the foam material, the stress peak decreases one order of magnitude and the duration is more than four times that of the panel without the soft layer by numerical simulation. Additionally, the multi layered medium with concrete foam demonstrates the favourable protective property compared with that of aluminum foam. Meanwhile, the optimal analysis of the thickness of the foam material in the sandwich panel was performed in terms of experimental and numerical analyseis. The proper thickness proportion of soft layer is about 20 percent to the total thickness of sandwich panel under the conditions in this study.Defence Science Journal, 2009, 59(1, pp.22-29, DOI:http://dx.doi.org/10.14429/dsj.59.1480  

  10. Experimental study on settlement of model piles in frozen soil under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    张建明; 朱元林; 张家懿

    1999-01-01

    Test results show that the settlement process of model piles is mainly the rheological process of frozen soil under shear loading. The settlement rate of model piles increases with increasing temperature of frozen soil, decreasing roughness of pile surface and increasing rigidity of pile foundation. As the water content of frozen soil reaches its saturation value, the settlement rate is the least. When the level of loading is higher, the settlement rate under dynamic loading is less than that under static loading. With the level of loading lowering, the effect between dynamic and static loading on the settlement rate becomes close gradually. Under the present test conditions, the settlement rate of model piles is independent of the frequency of dynamic loads.

  11. Influence of posturographic platform biofeedback training on the dynamic balance of adult stroke patients.

    Science.gov (United States)

    Maciaszek, Janusz; Borawska, Sylwia; Wojcikiewicz, Jacek

    2014-07-01

    The aim of the experiment was to analyze the influence of posturographic platform biofeedback training on the dynamic balance of patients who experienced ischemic stroke. The study included 21 patients treated at the Rehabilitation Center of the District Hospital in Białogard, in the Ward of Neurological Rehabilitation with the Stroke Division. The age of the patients (11 in the experimental and 10 in the control group) ranged between 55 and 65 years. The level of dynamic balance was determined with Timed Up and Go Test. The experimental group was subjected to the biofeedback training, practicing maintenance of body balance (forced sway training) on posturographic platform for 15 consecutive days. The perception of dynamic balance in the group subjected to biofeedback training improved to a markedly greater extent (P biofeedback training exerted stronger effect on the dynamic balance of patients who experienced the stroke of the left hemisphere with right-sided hemiparesis than in those with right hemisphere stroke and left-sided hemiparesis. The utilization of feedback mechanisms during training on a posturographic platform can be reflected by enhanced stimulation and further improvement of the control of performed motor tasks.

  12. Research of dynamic loading in a drivetrain by means of mathematical modeling

    Science.gov (United States)

    Sokolov-Dobrev, N. S.; Ljashenko, M. V.; Shekhovtsov, V. V.; Potapov, P. V.

    2017-02-01

    This paper describes the development of the initial full dynamic model of a caterpillar agricultural tractor ‘Chetra 6C-315’ drivetrain, the processes of the model reduction; the mathematical apparatus for defining loads acting on drivetrain shafting elements. The main results of computational researches of dynamic loadings of drivetrain elements in various tractor operation modes are presented.

  13. Dynamic Balance of Excitation and Inhibition in Human and Monkey Neocortex

    Science.gov (United States)

    Dehghani, Nima; Peyrache, Adrien; Telenczuk, Bartosz; Le van Quyen, Michel; Halgren, Eric; Cash, Sydney S.; Hatsopoulos, Nicholas G.; Destexhe, Alain

    2016-03-01

    Balance of excitation and inhibition is a fundamental feature of in vivo network activity and is important for its computations. However, its presence in the neocortex of higher mammals is not well established. We investigated the dynamics of excitation and inhibition using dense multielectrode recordings in humans and monkeys. We found that in all states of the wake-sleep cycle, excitatory and inhibitory ensembles are well balanced, and co-fluctuate with slight instantaneous deviations from perfect balance, mostly in slow-wave sleep. Remarkably, these correlated fluctuations are seen for many different temporal scales. The similarity of these computational features with a network model of self-generated balanced states suggests that such balanced activity is essentially generated by recurrent activity in the local network and is not due to external inputs. Finally, we find that this balance breaks down during seizures, where the temporal correlation of excitatory and inhibitory populations is disrupted. These results show that balanced activity is a feature of normal brain activity, and break down of the balance could be an important factor to define pathological states.

  14. Issues in the Usage of MANETs as Backup or Load-Balancing Transit Networks of the Internet

    Directory of Open Access Journals (Sweden)

    Quan Le Trung

    2006-05-01

    Full Text Available Internetworking the mobile ad-hoc networks (MANETs with the Internet has been a hot issue for many years. However, most researches have been concentrated on the use of MANETs as the access networks for the Internet. This paper introduces another use of MANETs: backup or load-balancing transit networks for the Internet. Although the MANETs capacity is currently low compared with other backbone technologies, we argue that MANETs is a suitable alternative for backup or load-balancing transit networks of the Internet based on its self-organized infrastructure-less multi-hop architecture and its increasing capacity in the near future. To provide the backup or load-balancing transit services for the Internet, a scalable, stable, lowoverhead, QoS-support ad-hoc routing architecture with the address auto-configuration is required. Moreover, how an Internet gateway selects an external route via MANETs to another autonomous system (AS also needs to be solved. In this paper, BGP-GCR+, a combination of the border gateway protocol (BGP, the gravitational cluster routing (GCR, and the passive/weak IPv6-based address stateless auto-configuration, is developed towards the standards to achieve the required functions. We have implemented of the routing component of our proposed BGP-GCR+ routing architecture [1] into ns-2 for the performance evaluation. Results show that the packet delivery ratio under high traffic load and mobility in BGPGCR+ is lower than that in AODV-Hello for small-scale (50-150 nodes, but slightly higher for the medium-scale (200 nodes MANETs. For lower mobility and traffic load, the performance of both BGP-GCR+ and AODV-Hello are high (over 90%. Moreover, the routing overhead is much lower (almost one-half in BGP-GCR+ compared with AODV in all test cases. The implementation of other components of BGP-GCR+ in ns-2 and the mapping of medium access control (MAC-related metrics into the link stability of the cluster construction in BGP-GCR+ for

  15. A Simple Method for Static Load Balancing of Parallel FDTD Codes

    DEFF Research Database (Denmark)

    Franek, Ondrej

    2016-01-01

    is described for partitioning in a single mesh dimension, but it is shown that it can be adapted also for 2D and 3D partitioning in approximate way, with good results. It is applicable to both homogeneous and heterogeneous parallel architectures, and can also be used for balancing memory on distributed memory...

  16. Carrier Load Balancing and Packet Scheduling for Multi-Carrier Systems

    DEFF Research Database (Denmark)

    Wang, Yuanye; Pedersen, Klaus; Sørensen, Troels Bundgaard

    2010-01-01

    methods for allocating the CCs to the users- Round Robin (RR) and Mobile Hashing (MH) balancing by means of a simple theoretical formulation, as well as system level simulations. At Layer-2 we propose a simple cross-CC packet scheduling algorithm that improves the coverage performance and the resource...

  17. Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

    2016-06-01

    The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

  18. An improved technique for the reconstruction of former glacier mass-balance and dynamics

    Science.gov (United States)

    Carr, Simon; Coleman, Christopher

    2007-11-01

    The recognition of past glacier extent and dynamics is a fundamental aspect of investigations of the climatic sensitivity of glaciers, especially when examining short-lived climate events such as the Younger Dryas or Little Ice Age. Existing approaches to the reconstruction of glacier form and dynamics depend on speculative reasoning of key glacier dynamic parameters, including the role of basal slip and subglacial deformation in glacier mass-transfer. This study reviews approaches to glacier reconstruction, derivation of former glacier equilibrium line altitudes (ELA's) and estimation of mass-balance and dynamics, concluding that most reconstructions of glacier mass-balance are compromised by a lack of glaciological considerations. An alternative approach to glacier reconstruction is presented, demonstrated and discussed, by which an empirical relationship between ablation gradient and mass loss at the ELA is used to derive mass-balance, mass-flux through the ELA and average balance velocity at the ELA. This 'glaciological' approach is applied to four reconstructed glaciers to test previous interpretations that each reflects Younger Dryas glaciation in the UK. The study concludes that this approach provides a more robust technique for reconstructing former glacier dynamics, and may be applied to test geomorphological interpretations of former mountain glaciation.

  19. Closure behavior of rock joint under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-hua; LI Xi-bing; ZHANG Yi-ping; ZUO Yu-jun

    2007-01-01

    The normal compression tests on intact samples and artificial joints with different saw-tooth shape under cyclic loading and half-sine waves of different frequencies were performed by using Instron1342 servo-controlled material testing machine. The specimens were made artificially with mortar. The loading frequency ranged from 0.005 Hz to 0.1 Hz. The experimental results show that joint closure curves are non-linear and concave up. The stress-deformation curves under cyclic loading exhibit hysteresis and permanent set that diminish rapidly and keep constant finally on successive cycles. Normal displacement successively decreases from the joint J1 to J2, to J3 under the same normal loads regardless of frequency. Considering the loading frequency effect, normal displacement of joint J1 decreases with increasing the loading frequency except that the loading frequency is 0.05 Hz. Normal displacement of joint J2 increases with increasing the loading frequency. Normal displacement of joint J3 increases with increasing the loading frequency when the frequency ranges from 0.005 Hz to 0.05 Hz. Its normal displacement, however, becomes least when the loading frequency is 0.1 Hz.

  20. Halovest dynamic loads: full crossover comparison of three vest types.

    Science.gov (United States)

    Fukui, Yasuyuki; Krag, Martin; Huston, Dryver; Ambrose, Tim; Vaccaro, Alexander R

    2002-02-01

    Ten cervical spine trauma subjects were studied during halovest treatment. Each subject wore each of three different vests. To compare the effect of vest design on loads between halo and vest during various activities. Complications during halovest use may be related to vest design, a variety of which are available. Loads between halo and vest have been shown to vary with activity type, but no comparison between vest types has been reported previously. Loads between the halo and the vest were measured during performance of activities of daily living and during load application to the halo, using custom-built four-channel transducers and a PC-based data acquisition system. Substantial variations between subjects exist in loads between the halo and the vest. At rest, neck distraction loads were significantly greater for the supine posture than for either the sitting or standing postures. Loads applied to the halo by the investigators are carried by the neck and not by the structure connecting the halo to the vest. During activities of daily living all four measured load components are generally nonzero. During activities of daily living substantial differences in loads occurred between vest types. For all activities of daily living combined, the relative neck distraction load values were as follows: 4PAD 100%, Bremer 159%, and PMT 180%. Previous evidence supports a connection between certain complications of halovest wear (such as pin loosening) and loads on the pins. This study shows that different halovests are associated with quite different loads between the vest and the halo (and thus loads on the pins and the neck). This is encouraging for prospective, clinical comparison of different halovests and for improvements in clinical performance through halovest design improvements.

  1. Nonlinear dynamics and load sharing of double-mesh helical gear train

    Directory of Open Access Journals (Sweden)

    Fuchun Yang

    2013-07-01

    Full Text Available Dynamic behaviours and load sharing of double-mesh helical gear trains have been studied in this paper. A nonlinear dynamic model of double-mesh helical gear train was established, including torsional vibration, axial vibration, timevarying mesh stiffness and backlashes. The governing equations were solved by Runge-Kutta method. Frequency responses and influences of main parameters to frequency responses were analyzed to determine the vibration characteristics of the system. The dynamic factor and load sharing in two mesh pairs were studied in two configuration cases and the result shows that case II has better dynamic response and load sharing.

  2. The Position of the Patella and Extensor Mechanism Affects Intraoperative Compartmental Loads During Total Knee Arthroplasty: A Pilot Study Using Intraoperative Sensing to Guide Soft Tissue Balance.

    Science.gov (United States)

    Schnaser, Erik; Lee, Yuo-yu; Boettner, Friedrich; Gonzalez Della Valle, Alejandro

    2015-08-01

    The achievement of a well-balanced total knee arthroplasty is necessary for long-term success. We hypothesize that the dislocation of the patella during surgery affects the distribution of loads in the medial and lateral compartments. Intraoperative load sensors were used to record medial and lateral compartment loads in 56 well-balanced TKAs. Loads were recorded in full extension, relaxed extension, at 45 and 90° of flexion at full gravity-assisted flexion, with the patella in four different positions: dislocated (everted and not), located, and located and secured with two retinacular sutures. The loads in the lateral compartment in flexion were higher with a dislocated patella than with a located patella (Ppatella in a physiologic position are more likely to replicate postoperative compartment loads. II (prospective comparative study). Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  3. The Relationship of Core Strength with Static and Dynamic Balance in Children with Autism

    Directory of Open Access Journals (Sweden)

    Sarvin Salar

    2014-12-01

    Full Text Available Autism represents a disorder of neural development characterized by 3 features including deficit in social communication, inflexibility of speech and behavior, and stereotyped movements. The prevalence of this disorder has been reported about 1.5 per 100 individuals in Iran. Individuals with ASDs are susceptible to weakness in balance and stability and also postural deformities. Thus, the purpose of this study was to determine the relationship between core strength and balance in children with autism. The subjects included 32 boys with ASDs aged 6-10 (mean and standard deviation of 8.16 ± 1.16 years, 124.81 ± 11.56 cm in height, 33.02± 7.72 kg weight and body mass index 21.12 ± 3.14 kg/m2. They were selected according to available sampling method. In order to assess the maximum isometric strength of hip abduction and external rotation, manual muscle test dynamometer was used. Static and dynamic balance were also tested by modified stork standing test and walking heel to toe test, respectively. The results showed that there is no correlation between core strength and static balance in dominant and non-dominant leg, but there is a significant correlation between dynamic balance and core strength. According to the results, it is recommended that development of parameters related to the core body strength to be emphasized for improving balance in such children.

  4. Two Dimensional Array Based Overlay Network for Balancing Load of Peer-to-Peer Live Video Streaming

    Science.gov (United States)

    Faruq Ibn Ibrahimy, Abdullah; Rafiqul, Islam Md; Anwar, Farhat; Ibn Ibrahimy, Muhammad

    2013-12-01

    The live video data is streaming usually in a tree-based overlay network or in a mesh-based overlay network. In case of departure of a peer with additional upload bandwidth, the overlay network becomes very vulnerable to churn. In this paper, a two dimensional array-based overlay network is proposed for streaming the live video stream data. As there is always a peer or a live video streaming server to upload the live video stream data, so the overlay network is very stable and very robust to churn. Peers are placed according to their upload and download bandwidth, which enhances the balance of load and performance. The overlay network utilizes the additional upload bandwidth of peers to minimize chunk delivery delay and to maximize balance of load. The procedure, which is used for distributing the additional upload bandwidth of the peers, distributes the additional upload bandwidth to the heterogeneous strength peers in a fair treat distribution approach and to the homogeneous strength peers in a uniform distribution approach. The proposed overlay network has been simulated by Qualnet from Scalable Network Technologies and results are presented in this paper.

  5. Strength properties of the jointed rock mass medium under dynamic cyclic loading *

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dynamic strength properties of the intermittently jointed mediums are studied using model test to investigate the jointed rock mass behavior under dynamic cyclic load. The model test results demonstrate that (i) the dynamic strength of the jointed samples increases with the loading frequency and decreases with the loading loops; (ii) the dynamic residual strength will not be zero like the static residual strength under one-axle loading condition; (iii) the dynamic strength changes greatly with the joint density and joint angle, and it differs from that of the static strength which reaches the lowest at an angle of 45° + ψ/2, while in the dynamic case, the lowest strength is at the angle of 45°.

  6. Dynamic Balanced Scorecard for companies in the business field of power supply; Dynamic Balanced Scorecard fuer Unternehmen im Geschaeftsfeld der dezentralen Energieversorgung

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, M.; Roy, I. [Paderborn Univ. (Germany). Lehrstuhl fuer Nachhaltige Energiekonzepte

    2006-06-19

    Due to deregulation and liberalisation of the power market and due to the opting out of the nuclear energy, the decentralized power supply increasingly gains in importance in comparison to the classical power supply. Thus, the entrepreneur who wants to engage in the decentralized power supply needs a management tool for conversion and supervision his strategy. A pertinent means for this already is the Dynamic Balanced Scorecard. By means of an evaluation of a simple balanced scorecard, the entrepreneur realizes his vision and strategy in order to determine the success-critical factors. These success-critical factors are related together in a causal chain. By this, the entrepreneur can recognize, what has to be done in order to act successfully on the market, and in order to secure the success on a long-term basis. The modelling of the Dynamic balanced Scorecard enables the examination of the corporate strategy, before it is implemented in the enterprise. Thus, the entrepreneur saves time and minimizes the corporate risk.

  7. Numerical modeling of sandwich panel response to ballistic loading - energy balance for varying impactor geometries

    DEFF Research Database (Denmark)

    Kepler, Jørgen Asbøl; Hansen, Michael Rygaard

    2007-01-01

    thickness but significantly smaller than panel length dimensions. Experimental data for the total loss in impactor kinetic energy and momentum and estimated damage energy are described. For a selection of impactor tip shapes, the numerical model is used to evaluate different simplified force histories...... between the impactor and the panel during penetration. The force histories are selected from a primary criterion of conservation of linear momentum in the impactor-panel system, and evaluated according to agreement with the total measured energy balance....

  8. System Dynamic Modelling for a Balanced Scorecard: A Case Study

    DEFF Research Database (Denmark)

    Nielsen, Steen; Nielsen, Erland Hejn

    Purpose - The purpose of this research is to make an analytical model of the BSC foundation by using a dynamic simulation approach for a 'hypothetical case' model, based on only part of an actual case study of BSC. Design/methodology/approach - The model includes five perspectives and a number...... variables: skills, customer base and work in process. We are able to show that only minimal changes may create large effects on profit. Research limitations/implications - Our analytical model is based on both assumed but also on case documented assumptions of a concrete model. In every such kind of model...... and the number of measures. Originality/value - A large number of case studies and surveys are now present in the literature of BSC. However, there is a lack of more theoretical and analytical modelling of the BSC. Our paper just throws a little light to this modelling approach....

  9. The Delicate Balance of Static and Dynamic Electron Correlation

    CERN Document Server

    Stein, Christopher J; Reiher, Markus

    2016-01-01

    Multi-configurational approaches yield universal wave function parameterizations that can qualitatively well describe electronic structures along reaction pathways. For quantitative results, multi-reference perturbation theory is required to capture dynamic electron correlation from the otherwise neglected virtual orbitals. Still, the overall accuracy suffers from the finite size and choice of the active orbital space and peculiarities of the perturbation theory. Fortunately, the electronic wave functions at equilibrium structures of reactants and products can often be well described by single-reference methods and hence are accessible to accurate coupled cluster calculations. Here, we calculate the heterolytic double dissociation energy of four 3d-metallocenes with the complete active space self-consistent field method and compare to highly accurate coupled cluster data. Our coupled cluster data are well within the experimental error bars. This accuracy can also be approached by complete active space calcula...

  10. Effect of smart phone using duration and gender on dynamic balance

    Directory of Open Access Journals (Sweden)

    Doaa Rafat El Azab

    2017-01-01

    Full Text Available Smart phones are constantly used for extended periods while looking at the visual display terminals this may causes musculoskeletal problems. So, the purpose of this study was to investigate effect of smart phone using duration and gender on dynamic balance. Subjects: Sixty normal subjects included in this study their age ranged from 20 years to 35 years were divided into three groups, A not using smart phone, B using smart phone less than 4 h per day, C using smart phone more than 4 h per day. Methods: Biodex Stability System was utilized to assess dynamic balance; 3 trials were performed from which the mean value was calculated. Results: there is a significant decrease in all balance directions for group B and C (using smart phone with favor reduction for group C (using smart phone more than 4 h per day and there is a significant difference between male and female subjects as dynamic balance decreased more in female subjects more than male subjects. Conclusion: Long duration of smart phone using affect negatively the balance ability especially in females, so we should develop preventive programs to alleviate its negative effects.

  11. Dynamic Response to Pedestrian Loads with Statistical Frequency Distribution

    DEFF Research Database (Denmark)

    Krenk, Steen

    2012-01-01

    Pedestrian loads depend on the regularity and frequency of the footfall process. Traditionally, pedestrian loads have been represented by one or more specific harmonic components with a well-defined frequency, and light footbridges have been investigated for resonance vibration generated by the h......Pedestrian loads depend on the regularity and frequency of the footfall process. Traditionally, pedestrian loads have been represented by one or more specific harmonic components with a well-defined frequency, and light footbridges have been investigated for resonance vibration generated...

  12. Studying plastic shear localization in aluminum alloys under dynamic loading

    Science.gov (United States)

    Bilalov, D. A.; Sokovikov, M. A.; Chudinov, V. V.; Oborin, V. A.; Bayandin, Yu. V.; Terekhina, A. I.; Naimark, O. B.

    2016-12-01

    An experimental and theoretical study of plastic shear localization mechanisms observed under dynamic deformation using the shear-compression scheme on a Hopkinson-Kolsky bar has been carried out using specimens of AMg6 alloy. The mechanisms of plastic shear instability are associated with collective effects in the microshear ensemble in spatially localized areas. The lateral surface of the specimens was photographed in the real-time mode using a CEDIP Silver 450M high-speed infrared camera. The temperature distribution obtained at different times allowed us to trace the evolution of the localization of the plastic strain. Based on the equations that describe the effect of nonequilibrium transitions on the mechanisms of structural relaxation and plastic flow, numerical simulation of plastic shear localization has been performed. A numerical experiment relevant to the specimen-loading scheme was carried out using a system of constitutive equations that reflect the part of the structural relaxation mechanisms caused by the collective behavior of microshears with the autowave modes of the evolution of the localized plastic flow. Upon completion of the experiment, the specimens were subjected to microstructure analysis using a New View-5010 optical microscope-interferometer. After the dynamic deformation, the constancy of the Hurst exponent, which reflects the relationship between the behavior of defects and roughness induced by the defects on the surfaces of the specimens is observed in a wider range of spatial scales. These investigations revealed the distinctive features in the localization of the deformation followed by destruction to the script of the adiabatic shear. These features may be caused by the collective multiscale behavior of defects, which leads to a sharp decrease in the stress-relaxation time and, consequently, a localized plastic flow and generation of fracture nuclei in the form of adiabatic shear. Infrared scanning of the localization zone of the

  13. Dynamics of Non-Uniformity Loads of Afc Drives

    Science.gov (United States)

    Dolipski, Marian; Remiorz, Eryk; Sobota, Piotr

    2014-03-01

    The length of armoured face conveyors currently used in hard coal mines most often ranges between 200 m and 300 m. The machines are equipped with a main and auxiliary drive. Asynchronous motors mounted in conveyor drives feature the capacity of several hundreds of kilowatts. The non-uniform distribution of loads onto individual drives is observed in practice. The numerical value of loads distribution onto the individual armoured face conveyor drives is represented by a drive load distribution factor. It is defined as a ratio between the load of an electric motor installed in a given drive and the total conveyor load. The article presents a physical armoured face conveyor model intended for examining dynamic phenomena influencing the load non-uniformity of drives. Motion in this physical model is described with the system of (4 · j + 5) non-linear ordinary differential quotations of the second order. A mathematical model is obtained by adding functions describing the interwork of sprocket drums with chains and functions approximating the mechanical characteristics of asynchronous motors powered by means of frequency inverters. A large number of computer simulations was performed using this model enabling to study the impact on the load non-uniformity of drives of such parameters as motor slip, motor supply voltage drop, variations in supply voltage frequency, differences in the gear ratio of transmissions and differentiation in the pitch of scraper chain links along the chain contour. Długość przenośników zgrzebłowych ścianowych stosowanych obecnie w kopalniach węgla kamiennego najczęściej mieści się w przedziale od 200 m do 300 m. Maszyny te wyposażone są zawsze w napęd główny i pomocniczy, przy czym pierwszy z nich wyniesiony jest do chodnika podścianowego. Silniki napędowe o mocy kilkuset kilowatów napędzają bęben łańcuchowy przez sprzęgło i przekładnię zębatą. Z kolei bębny łańcuchowe poruszają łańcuch zgrzebłowy, kt

  14. Numerical Analysis of Dynamic Behavior of RC Slabs Under Blast Loading

    Institute of Scientific and Technical Information of China (English)

    DU Hao; LI Zhongxian

    2009-01-01

    In Order to reduce economic and life losses due to terrorism or accidental explosion threats,reinforced concrete(RC)slabs of buildings need to be designed or retrofitted to resist blast loading.In this paper the dynamic behavior Of RC slabs under blast loading and its influencing factors are studied.The numerical model of an RC slab subjected to blast loading is established using the explicit dynamic analysis software.Both the strain rate effect and the damage accumulation are taken into account in the material model.The dynamic responses of the RC slab subiected to blast loading are analyzed,and the influence of concrete strength,thickness and reinforcement ratio on the behavior of the RC slab under blast loading iS numerically investigated.Based on the numerical results.some principles for blast-resistant design and retrofitting are proposed to improve the behavior of the RC slab subjected to blast loading.

  15. On the balance energy and nuclear dynamics in peripheral heavy-ion collisions

    CERN Document Server

    Chugh, Rajiv

    2010-01-01

    We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of $Ne^{20}+Ne^{20}$, $Ca^{40}+Ca^{40}$, $Ni^{58}+Ni^{58}$, $Nb^{93}+Nb^{93}$, $Xe^{131}+Xe^{131}$ and $Au^{197}+Au^{197}$ are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon-nucleon cross-sections between 40 - 55 mb explains the data nicely. Interestingly, balance energy follows a power law $\\propto{A^{\\tau}}$ for the mass dependence at all colliding geometries. The power factor $\\tau$ is close to -1/3 in central collisions whereas it is -2/3 for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point.

  16. DOUBLE FOUR-BAR CRANK-SLIDER MECHANISM DYNAMIC BALANCING BY META-HEURISTIC ALGORITHMS

    Directory of Open Access Journals (Sweden)

    Habib Emdadi

    2013-09-01

    Full Text Available In this paper, a new method for dynamic balancing of double four-bar crank slider mechanism by metaheuristic-based optimization algorithms is proposed. For this purpose, a proper objective function which is necessary for balancing of this mechanism and corresponding constraints has been obtained by dynamic modeling of the mechanism. Then PSO, ABC, BGA and HGAPSO algorithms have been applied for minimizing the defined cost function in optimization step. The optimization results have been studied completely by extracting the cost function, fitness, convergence speed and runtime values of applied algorithms. It has been shown that PSO and ABC are more efficient than BGA and HGAPSO in terms of convergence speed and result quality. Also, a laboratory scale experimental doublefour-bar crank-slider mechanism was provided for validating the proposed balancing method practically.

  17. Changes in dynamic balance control over time in children with and without Developmental Coordination Disorder

    NARCIS (Netherlands)

    Jelsma, L.D.; Smits-Engelsman, B. C. M.; Krijnen, W. P.; Geuze, R.H.

    2016-01-01

    The aim of this study was to examine differences in underlying adaptations of dynamic balance in children with and without Developmental Coordination Disorder (DCD) during a Wii Fit game and to measure changes over time and after intervention. Twenty-eight children with DCD and 21 typically developi

  18. Changes in dynamic balance control over time in children with and without Developmental Coordination Disorder

    NARCIS (Netherlands)

    Jelsma, L.D.; Smits-Engelsman, B. C. M.; Krijnen, W. P.; Geuze, R.H.

    2016-01-01

    The aim of this study was to examine differences in underlying adaptations of dynamic balance in children with and without Developmental Coordination Disorder (DCD) during a Wii Fit game and to measure changes over time and after intervention. Twenty-eight children with DCD and 21 typically

  19. The Analysis of the Development Dynamics and Structural Balance of Solar Energy in the World

    Science.gov (United States)

    Brand, A. E.; Chekardovskiy, S. M.; Akulov, K. A.

    2017-01-01

    The paper presents data the analysis of the development dynamics and structural balance of solar energy in the world. In the article presents information about total installed production capacity of solar energy, the world solar energy production capacity distribution and the European Union energy market structure in 2000 and 2015 years.

  20. Changes in dynamic balance control over time in children with and without Developmental Coordination Disorder

    NARCIS (Netherlands)

    Jelsma, L.D.; Smits-Engelsman, B. C. M.; Krijnen, W. P.; Geuze, R.H.

    2016-01-01

    The aim of this study was to examine differences in underlying adaptations of dynamic balance in children with and without Developmental Coordination Disorder (DCD) during a Wii Fit game and to measure changes over time and after intervention. Twenty-eight children with DCD and 21 typically developi

  1. Short-term motor learning of dynamic balance control in children with probable Developmental Coordination Disorder

    NARCIS (Netherlands)

    Jelsma, Dorothee; Ferguson, Gilian D.; Smits-Engelsman, Bouwien C.M.; Geuze, Reint H.

    2015-01-01

    Purpose: To explore the differences in learning a dynamic balance task between children with and without probable Developmental Coordination Disorder (p-DCD) from different cultural backgrounds. Participants: Twenty-eight Dutch children with DCD (p-DCD-NL), a similar group of 17 South African childr

  2. Changes in dynamic balance control over time in children with and without Developmental Coodination Disorder

    NARCIS (Netherlands)

    Jelsma, L.D.; Smits-Engelsman, B.C.M.; Geuze, R.H.

    2015-01-01

    Changes in dynamic balance control over time in children with and without Developmental Coordination Disorder L.D. Jelsma1, B.C.M. Smits-Engelsman2 & R.H. Geuze1 1Clinical and Developmental Neuropsychology, University of Groningen, Grote Kruisstraat 2-1, 9712 TS Groningen, the Netherlands. l.d.jelsm

  3. INFLUENCE OF LOADING RATE ON DYNAMIC FRACTURE BEHAVIOR OF FIBER-REINFORCED COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Kezhuang Gong; Zheng Li; Weizhong Qin

    2008-01-01

    The effect of loading rate on the dynamic fracture properties and the failure mechanisms of glass fiber-reinforced composite materials under mode I fracture is studied.Dynamic reflective caustic experiments are carried out for two loading rates.By measuring the characteristic dimensions of the shadow spots during the caustic experiments,the dynamic SIFs are calculated for different loading rates.The experimental results indicate that the dynamic fracture toughness KId increases remarkably with increasing loading rate,and the crack grows faster under the high-velocity impact.Moreover,by examining the crack growth routes and the fracture surfaces,it is shown that the loading rate also greatly affects the failure mechanisms at micro-scale.

  4. Prediction onset and dynamic behaviour of liquid loading gas wells

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Schiferli, W.; Alberts, G.J.N.; Veeken, C.A.M.; Biezen, E.

    2008-01-01

    As reservoir pressures decrease in maturing gas wells, liquid drop-out forms an increasing restriction on gas production. Even though virtually all of the world's gas wells are either at risk of or suffering from liquid loading, the modeling of liquid loading behavior is still quite immature and the

  5. Dynamic Response of Coarse Granular Material to Wave Load

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    1998-01-01

    The soil beneath vertical breakwaters is subjected to a combination of forces induced by the waves. The forces acting on the soil can be characterized as 1) static load due to submerged weight of the structure, 2) quasi-static forces induced by cyclic wave loading, and 3) wave impact from breakin...

  6. Automated load balancing in the ATLAS high-performance storage software

    CERN Document Server

    Le Goff, Fabrice; The ATLAS collaboration

    2017-01-01

    The ATLAS experiment collects proton-proton collision events delivered by the LHC accelerator at CERN. The ATLAS Trigger and Data Acquisition (TDAQ) system selects, transports and eventually records event data from the detector at several gigabytes per second. The data are recorded on transient storage before being delivered to permanent storage. The transient storage consists of high-performance direct-attached storage servers accounting for about 500 hard drives. The transient storage operates dedicated software in the form of a distributed multi-threaded application. The workload includes both CPU-demanding and IO-oriented tasks. This paper presents the original application threading model for this particular workload, discussing the load-sharing strategy among the available CPU cores. The limitations of this strategy were reached in 2016 due to changes in the trigger configuration involving a new data distribution pattern. We then describe a novel data-driven load-sharing strategy, designed to automatical...

  7. The Power of Slightly More than One Sample in Randomized Load Balancing

    Science.gov (United States)

    2015-04-26

    of which can be executed in parallel in possibly different servers. In queueing theory parlance, this model differs from the models mentioned earlier...goal of minimizing queueing delays. When the number of processors is very large, a popular routing algorithm works as follows: select two servers...at random and route an arriving task to the least loaded of the two. It is well- known that this algorithm dramatically reduces queueing delays

  8. Dynamic Response of Offshore Wind Turbines subjected to Joint Wave and Wind Loads

    DEFF Research Database (Denmark)

    Liu, Weiliang; Chen, Jianbing; Liu, Wenfeng;

    2013-01-01

    into consideration. Wind and wave loads are generated by the physical random models. The aerodynamic loads on blades are calculated by the Blade Element Momentum (BEM) theory, and the wave loads are calculated by the linear theory of wave. The dynamic response of the NREL-5MW wind turbine system is carried out......This paper investigates the dynamic response of offshore wind turbine systems subjected joint wind and wave loads. Relying on the finite element model, Kane’s equation is adopted to consider the rotation of blades. Besides, the generator-torque control and blade-pitch control are taken...

  9. Effects of fundamental structure parameters on dynamic responses of submerged floating tunnel under hydrodynamic loads

    Institute of Scientific and Technical Information of China (English)

    Xu Long; Fei Ge; Lei Wang; Youshi Hong

    2009-01-01

    This paper investigates the effects of structure parameters on dynamic responses of submerged floating tunnel (SFT) under hydrodynamic loads. The structure parameters includes buoyancy-weight ratio (BWR), stiffness coefficients of the cable systems, tunnel net buoyancy and tunnel length. First, the importance of structural damp in relation to the dynamic responses of SFT is demonstrated and the mechanism of structural damp effect is discussed. Thereafter, the fundamental structure parameters are investi-gated through the analysis of SFT dynamic responses under hydrodynamic loads. The results indicate that the BWR of SFT is a key structure parameter. When BWR is 1.2, there is a remarkable trend change in the vertical dynamic response of SFT under hydrodynamic loads. The results also indicate that the ratio of the tunnel net buoyancy to the cable stiffness coefficient is not a characteristic factor affecting the dynamic responses of SFT under hydrodynamic loads.

  10. Constitutive model of rock under static-dynamic coupling loading and experimental investigation

    Institute of Scientific and Technical Information of China (English)

    LI Xi-bing; ZUO Yu-jun; WANG Wei-hua; MA Chun-de; ZHOU Zi-long

    2006-01-01

    The importance of study on constitutive model of statically loaded rock experiencing dynamic load is set forth, and the studying methods on dynamic constitutive model are classified according to the current studying status. By way of combining statistic damage model and viscoelastic model, uni-axial and multi-axial constitutive models of statically loaded rock experiencing dynamic load (static-dynamic coupling constitutive model) under intermediate strain rate are established. The verification experiment on 2D constitutive model under different static stress and dynamic stress with different frequencies is designed and performed. It is found that there is a good agreement between the experimental stress-strain curves and the theoretical stress-strain curves.

  11. Investigating the tension load of rubber composites by impact dynamic testing

    Indian Academy of Sciences (India)

    L AMBRIŠKO; D MARASOVÁ; M CEHLÁR

    2017-04-01

    This work deals with establishing the tension load by impact dynamic testing of rubber composite conveyor belts. The value of tension load affects the shape of the used impactor and use of a support system as well as the weight of the ram and the impact height. An increase in the allowable stress when the belt is tensioned was examined during the test, to determine the effect of impact on the tension load. The obtained values of tension load are assessed using basic mathematical and statistical methods. Using the Design of Experiments method, factors that significantly affect the value of the tension load are identified.

  12. Dynamical response of hyper-elastic cylindrical shells under periodic load

    Institute of Scientific and Technical Information of China (English)

    REN Jiu-sheng

    2008-01-01

    Dynamical responses, such as motion and destruction of hyper-elastic cylindricai shells subject to periodic or suddenly applied constant load on the inner surface,are studied within a framework of finite elasto-dynamics. By numerical computation and dynamic qualitative analysis of the nonlinear differential equation, it is shown that there exists a certain critical value for the internal load describing motion of the inner surface of the shell. Motion of the shell is nonlinear periodic or quasi-periodic oscillation when the average load of the periodic load or the constant load is less than its critical value.However, the shell will be destroyed when the load exceeds the critical value. Solution to the static equilibrium problem is a fixed point for the dynamical response of the corresponding system under a suddenly applied constant load. The property of fixed point is related to the property of the dynamical solution and motion of the shell. The effects of thickness and load parameters on the critical value and oscillation of the shell are discussed.

  13. Balancing rotor speed regulation and drive train loads of floating wind turbines

    Science.gov (United States)

    Fischer, Boris; Loepelmann, Peter

    2016-09-01

    The interaction of the blade pitch controller with structural motion is particularly important for wind turbines mounted on floating platforms. A controls-based approach to overcome the related technical challenges is to feed back the nacelle's motion to the demanded generator torque. This work aims to further improve this approach by feeding back only a narrow fraction of the available frequency range. Simulations show that, in doing so, unrealistically high torque magnitudes are avoided, and better a trade-off between rotor speed regulation and drive train loads is achieved.

  14. A test of static and dynamic balance function in children with cochlear implants: the vestibular olympics.

    Science.gov (United States)

    Cushing, Sharon L; Chia, Ruth; James, Adrian L; Papsin, Blake C; Gordon, Karen A

    2008-01-01

    To determine the incidence of static and dynamic balance dysfunction in a group of children with profound sensorineural hearing loss receiving a cochlear implant and to assess the impact of cochlear implant activation on equilibrium. Observational cross-sectional study of children with single-sided implants, tested under 2 conditions: (1) implant on and (2) implant off in a random order. Ambulatory setting within an academic, tertiary care children's hospital. Forty-one children (ages 4-17 years) with cochlear implants comprised the study group. Fourteen children with normal hearing served as controls. All participants performed a standardized test of static and dynamic balance function (Bruininks-Oseretsky Test of Motor Proficiency 2 [BOT2], balance subset). Children with implants performed the BOT2 under the 2 randomized conditions. Overall performance on the balance subset of the BOT2 and the influence of implant activation on performance. The mean (SD) age-adjusted scale score for our control group was 17 (5) points (95% confidence interval [CI], 14-20), which was not significantly different (P = .15) from the published age-adjusted mean for the BOT2 balance subset (15 [5] points). The group that had undergone implantation, however, performed significantly more poorly (12 [ 6] points; 95% CI, 10-14) than either the control group or the published test mean (P = .004). Children with implants performed better with their implants on than with their implants off (mean [SD] difference, 1.3 [2.7] points; 95% CI, 0.3-2.3; P = .01). Large differences exist in the balance ability of children with sensorineural hearing loss requiring cochlear implantation compared with age-matched controls. Implant activation, however, conferred a slight advantage in accomplishing balance-related tasks. These results substantiate the need to further quantify the baseline vestibular dysfunction of our study population of children with cochlear implants, as well as the impact of implant

  15. Enhanced Dynamic Load Sensor for ISS (EDLS-ISS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aurora Flight Sciences and the Massachusetts Institute of Technology (MIT) propose to develop a stand-alone 6-DOF load sensing system that collects biomechanical...

  16. EFFECT OF GEAR WIDTH AND HELIX ANGLE ON FACTOR OF DYNAMIC LOAD OF DOUBLE CIRCULAR ARC HELICAL GEARING

    Institute of Scientific and Technical Information of China (English)

    Wu Baolin

    2004-01-01

    Based on theory of mechanical dynamics, meshing characteristic as well as the dynamic model of double circular arc helical gearing, an analysis approach and a computer program have been developed for studying the state of dynamic load and factor of dynamic load of the gearing, the changing situation of dynamic load and dynamic load factor vs some affecting factors such as gear width, helix angle and accuracy grade etc are investigated. A series of conclusions are obtained: ①With the increasing in the values of gear width, the dynamic load factor appears slow decreasing tendency in most region of gear width. ② When the accuracy grades of the gearing are improved, the values of dynamic load factor decrease. ③ The value of dynamic load factor appears a decreasing tendency with the increasing of value of helix angle at the same ratio of critical rotational speed.

  17. Influence of physical activity and different sensory conditions on static and dynamic balance of pregnant women

    Directory of Open Access Journals (Sweden)

    Vanessa Patrícia Soares de Sousa

    Full Text Available Abstract BACKGROUND Physical activity during pregnancy provides countless benefits to pregnant women and results in a smaller number of falls during pregnancy. Thus, this study aims to verify the influence of physical activity and test conditions on the static and dynamic balance of pregnant women. METHODOLOGY The study was an analytical, transversal, and comparative study with a sample of 99 pregnant women divided into two groups, with physical activity as the grouping factor. The evaluation included questions about the type and frequency of physical activity and investigation of postural balance (Balance Master System(r. For statistical analysis, we used the following tests: Shapiro Wilk, Mann-Whitney, ANOVA One Way and Wilcoxon. RESULTS No relationship was found between physical activity and postural balance (F > 0.40, P > 0.07. However, the test conditions alter the sway velocity (P = 0.001 and directional control movement (P = 0.001. CONCLUSIONS Results suggest that: (1 physical activity does not influence variables related to postural balance in active and sedentary pregnant women; and (2 postural sway velocity and directional control of movement are related to the test conditions used during balance evaluation.

  18. Dynamic balance control in elders: gait initiation assessment as a screening tool

    Science.gov (United States)

    Chang, H.; Krebs, D. E.; Wall, C. C. (Principal Investigator)

    1999-01-01

    OBJECTIVE: To determine whether measurements of center of gravity-center of pressure separation (CG-CP moment arm) during gait initiation can differentiate healthy from disabled subjects with sufficient specificity and sensitivity to be useful as a screening test for dynamic balance in elderly patients. SUBJECTS: Three groups of elderly subjects (age, 74.97+/-6.56 yrs): healthy elders (HE, n = 21), disabled elders (DE, n = 20), and elders with vestibular hypofunction (VH, n = 18). DESIGN: Cross-sectional, intact-groups research design. Peak CG-CP moment arm measures how far the subject will tolerate the whole-body CG to deviate from the ground reaction force's CP; it represents dynamic balance control. Screening test cutoff points at 16 to 18 cm peak CG-CP moment arm predicted group membership. RESULTS: The magnitude of peak CG-CP moment arm was significantly greater in HE than in DE and VH subjects (pphase in all groups. As a screening test, the peak moment arm has greater than 50% sensitivity and specificity to discriminate the HE group from the DE and VH groups with peak CG-CP moment arm cutoff points between 16 and 18 cm. CONCLUSIONS: Examining dynamic balance through the use of the CG-CP moment arm during single stance in gait initiation discriminates between nondisabled and disabled older persons and warrants further investigation as a potential tool to identify people with balance dysfunction.

  19. Effect of training on the muscle strength and dynamic balance ability of adults with down syndrome.

    Science.gov (United States)

    Tsimaras, Vassilios K; Fotiadou, Eleni G

    2004-05-01

    The purpose of this study was to evaluate the effect of training on the muscle strength and dynamic balance ability of adults with Down syndrome (DS). Twenty-five adults with DS were separated into 2 groups. Fifteen subjects (mean age, 24.5 years) constituted the experiment group, whereas 10 subjects (mean age, 24.7 years) were in the control group of the study. Parameters measured were peak torque, isokinetic muscle endurance, and dynamic balance ability. All subjects performed a leg strength test on a Cyber II isokinetic dynamometer. In addition, the subjects' dynamic balance ability was measured by means of a balance deck (Lafayette). The experimental group followed a 12-week training program. As the results indicated, the experimental group showed a statistically significant improvement in all measured values when compared with the control group. It is concluded that adults with DS can improve their physical and kinetic abilities with the application of a systematic and well-designed training program.

  20. Dynamic Balance Control of Multi-arm Free-Floating Space Robots

    Directory of Open Access Journals (Sweden)

    Bin Liang

    2008-11-01

    Full Text Available This paper investigates the problem of the dynamic balance control of multi-arm free-floating space robot during capturing an active object in close proximity. The position and orientation of space base will be affected during the operation of space manipulator because of the dynamics coupling between the manipulator and space base. This dynamics coupling is unique characteristics of space robot system. Such a disturbance will produce a serious impact between the manipulator hand and the object. To ensure reliable and precise operation, we propose to develop a space robot system consisting of two arms, with one arm (mission arm for accomplishing the capture mission, and the other one (balance arm compensating for the disturbance of the base. We present the coordinated control concept for balance of the attitude of the base using the balance arm. The mission arm can move along the given trajectory to approach and capture the target with no considering the disturbance from the coupling of the base. We establish a relationship between the motion of two arm that can realize the zeros reaction to the base. The simulation studies verified the validity and efficiency of the proposed control method.