• Title/Summary/Keyword: Service load

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Service Restoration Considering Load Balancing In Distribution Networks (부하균등화를 고려한 배전계통의 정전복구)

  • 최상열;김종형;신명철
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.9
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    • pp.513-520
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    • 2003
  • Service restoration is an emergency control in distribution constrol centers to restore out-of-service area as soon as possible when a fault occurs in distribution networks. therefore, it requires fast computation time and high quality solutions for load balancing. In this paper. a load balance index and heuristic guided best-first search are proposed for these problem. The proposed algorithm consists of two parts. One is to set up a decision tree to represent the various switching operations available. Another is to identify the most effective the set of switches using proposed search technique and a load balance index. Test results on the KEPCO's 108 bus distribution system show that the performance is efficient and robust.

A Implementation and Analysis on LBaaS(Load Balancing as a Service) based on Openstack (Openstack 기반 LBaaS 구현 및 분석)

  • Cho, Dong-Won
    • Proceedings of the Korea Information Processing Society Conference
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    • 2015.04a
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    • pp.164-166
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    • 2015
  • Recently, the implementations of private and public cloud service (IaaS: Infrastructure as a Service) have been growing rapidly. As a result, the need to provide High-Availability and Load-Balancing for the users has also increased. Openstack which is one of cloud computing solutions currently offers a feature to meet the need through an extension called Load Balancing as a Service (LBaaS). This paper will provide a detailed explanation about Openstack's LBaaS and its operation principle will be analyzed through the actual implementation.

Service life prediction of chloride-corrosive concrete under fatigue load

  • Yang, Tao;Guan, Bowen;Liu, Guoqiang;Li, Jing;Pan, Yuanyuan;Jia, Yanshun;Zhao, Yongli
    • Advances in concrete construction
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    • v.8 no.1
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    • pp.55-64
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    • 2019
  • Chloride corrosion has become the main factor of reducing the service life of reinforced concrete structures. The object of this paper is to propose a theoretical model that predicts the service life of chloride-corrosive concrete under fatigue load. In the process of modeling, the concrete is divided into two parts, microcrack and matrix. Taking the variation of mcirocrack area caused by fatigue load into account, an equation of chloride diffusion coefficient under fatigue load is established, and then the predictive model is developed based on Fick's second law. This model has an analytic solution and is reasonable in comparison to previous studies. Finally, some factors (chloride diffusion coefficient, surface chloride concentration and fatigue parameter) are analyzed to further investigate this model. The results indicate: the time to pit-to-crack transition and time to crack growth should not be neglected when predicting service life of concrete in strong corrosive condition; the type of fatigue loads also has a great impact on lifetime of concrete. In generally, this model is convenient to predict service life of chloride-corrosive concrete with different water to cement ratio, under different corrosive condition and under different types of fatigue load.

Influence of different fatigue loads and coating thicknesses on service performance of RC beam specimens with epoxy-coated reinforcement

  • Wang, Xiao-Hui;Gao, Yang;Gao, Run-Dong;Wang, Jing;Liu, Xi-La
    • Computers and Concrete
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    • v.19 no.3
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    • pp.243-256
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    • 2017
  • Epoxy-coated reinforcing bars are widely used to protect the corrosion of the reinforcing bars in the RC elements under their in-service environments and external loads. In most field surveys, it was reported that the corrosion resistance of the epoxy-coated reinforcing bars is typically better than the uncoated bars. However, from the experimental tests conducted in the labs, it was reported that, under the same loads, the RC elements with epoxy-coated reinforcing bars had wider cracks than the elements reinforced with the ordinary bars. Although this conclusion may be true considering the bond reduction of the reinforcing bar due to the epoxy coating, the maximum service loads used in the experimental research may be a main reason. To answer these two phenomena, service performance of 15 RC beam specimens with uncoated and epoxy-coated reinforcements under different fatigue loads was experimentally studied. Influences of different coating thicknesses of the reinforcing bars, the fatigue load range and load upper limit as well as fatigue load cycles on the mechanical performance of RC test specimens are discussed. It is concluded that, for the test specimens subjected to the comparatively lower load range and load upper limit, adverse effect on the service performance of test specimens with thicker epoxy-coated reinforcing bars is negligible. With the increments of the coating thickness and the in-service loading level, i.e., fatigue load range, load upper limit and fatigue cycles, the adverse factor resulting from the thicker coating becomes noticeable.

A Dynamic QoS Adjustment Enabled and Load-balancing-aware Service Composition Method for Multiple Requests

  • Wu, Xiaozhu
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.3
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    • pp.891-910
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    • 2021
  • Previous QoS-aware service composition methods mainly focus on how to generate composite service with the optimal QoS efficiently for a single request. However, in the real application scenarios, there are multiple service requests and multiple service providers. It is more important to compose services with suboptimal QoS and maintain the load balance between services. To solve this problem, in this paper, we propose a service composition method, named as dynamically change and balancing composition method (DCBC). It assumes that the QoS of service is not static, and the services can adjust the value of QoS to gain more opportunities to be selected for composition. The method mainly includes two steps, which are the preprocessing step and the service selection step. In the preprocessing step, a backward global best QoS calculation is performed which regarding the static and dynamic QoS respectively; then guided by the global QoS, the feasible services can be selected efficiently in the service selection step. The experiments show that the DCBC method can not only improve the overall quality of composite services but also guarantee the fulfill ratio of requests and the load balance of services.

A Study on the Service Load State Behavior of Reinforced Concrete Plate Member

  • Bhang, Jee-Hwan;Kang, Won-Ho
    • KCI Concrete Journal
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    • v.12 no.2
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    • pp.55-72
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    • 2000
  • This paper proposes a mechanical model to describe the load-deformation responses of the reinforced concrete plate members under service load state. An Analytical method is introduced on the basis of the rotating crack model which considers equilibrium, compatibility conditions, load-strain relationship of cracked member, and constitutive law for materials. The tension stiffening effect in reinforced concrete structures is taken into account by the average tensile stress-strain relationship from the load-strain relationship for the cracked member and the constitutive law for material. The strain compatibility is used to find out the crack direction because the crack direction is an unknown variable in the equilibrium and compatibility conditions. The proposed theory is verified by the numerous experimental data such as the crack direction, moment-steel strain relationship, moment-crack width relationship. The present paper can provide some basis for the provision of the definition of serviceability for plate structures of which reinforcements are deviated from the principal stresses, because the present code defines the serviceability by the deflection, crack control, vibration and fatigue basically for the skeletal members. The proposed theory is applicable to predict the service load state behavior of a variety of reinforced concrete plate structures such as skew slab bridges, the deck of skew girder bridges.

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Numerical study of concrete-encased CFST under preload followed by sustained service load

  • Li, Gen;Hou, Chao;Han, Lin-Hai;Shen, Luming
    • Steel and Composite Structures
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    • v.35 no.1
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    • pp.93-109
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    • 2020
  • Developed from conventional concrete filled steel tubular (CFST) members, concrete-encased CFST has attracted growing attention in building and bridge practices. In actual construction, the inner CFST is erected prior to the casting of the outer reinforced concrete part to support the construction preload, after which the whole composite member is under sustained service load. The complex loading sequence leads to highly nonlinear material interaction and consequently complicated structural performance. This paper studies the full-range behaviour of concrete-encased CFST columns with initial preload on inner CFST followed by sustained service load over the whole composite section. Validated against the reported data obtained from specifically designed tests, a finite element analysis model is developed to investigate the detailed structural behaviour in terms of ultimate strength, load distribution, material interaction and strain development. Parametric analysis is then carried out to evaluate the impact of significant factors on the structural behaviour of the composite columns. Finally, a simplified design method for estimating the sectional capacity of concrete-encased CFST is proposed, with the combined influences of construction preload and sustained service load being taken into account. The feasibility of the developed method is validated against both the test data and the simulation results.

Dynamic Load-Balancing Algorithm Incorporating Flow Distributions and Service Levels for an AOPS Node

  • Zhang, Fuding;Zhou, Xu;Sun, Xiaohan
    • Journal of the Optical Society of Korea
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    • v.18 no.5
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    • pp.466-471
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    • 2014
  • An asynchronous optical packet-switching (AOPS) node with load-balancing capability can achieve better performance in reducing the high packet-loss ratio (PLR) and time delay caused by unbalanced traffic. This paper proposes a novel dynamic load-balancing algorithm for an AOPS node with limited buffer and without wavelength converters, and considering the data flow distribution and service levels. By calculating the occupancy state of the output ports, load state of the input ports, and priorities for data flow, the traffic is balanced accordingly. Simulations demonstrate that asynchronous variant data packets and output traffic can be automatically balanced according to service levels and the data flow distribution. A PLR of less than 0.01% can be achieved, as well as an average time delay of less than 0.46 ns.

Research on the Application of Load Balancing in Educational Administration System

  • Junrui Han;Yongfei Ye
    • Journal of Information Processing Systems
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    • v.19 no.5
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    • pp.702-712
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    • 2023
  • Load balancing plays a crucial role in ensuring the stable operation of information management systems during periods of high user access requests; therefore, load balancing approaches should be reasonably selected. Moreover, appropriate load balancing techniques could also result in an appropriate allocation of system resources, improved system service, and economic benefits. Nginx is one of the most widely used loadbalancing software packages, and its deployment is representative of load-balancing application research. This study introduces Nginx into an educational administration system, builds a server cluster, and compares and sets the optimal cluster working strategy based on the characteristics of the system, Furthermore, it increases the stability of the system when user access is highly concurrent and uses the Nginx reverse proxy service function to improve the cluster's ability to resist illegal attacks. Finally, through concurrent access verification, the system cluster construction becomes stable and reliable, which significantly improves the performance of the information system service. This research could inform the selection and application of load-balancing software in information system services.

Crack Opening Behavior of Concrete Reinforced with High Strength Reinforcing Steel

  • Soltani, Amir;Harries, Kent A.;Shahrooz, Bahram M.
    • International Journal of Concrete Structures and Materials
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    • v.7 no.4
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    • pp.253-264
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    • 2013
  • A major difference between high-strength reinforcing steel and conventional steel in concrete is that the service-load steel stress is expected to be greater. Consequently, the service-load steel strains are greater affecting cracking behavior. A parametric study investigating crack widths and patterns in reinforced concrete prisms is presented in order to establish limits to the service-load steel stress and strain. Additionally, based on the results of available flexural tests, crack widths at service load levels were evaluated and found to be within presently accepted limits for highway bridge structures, and were predictable using current AASHTO provisions. A limitation on service-level stresses of $f_s{\leq}414$ MPa (60 ksi) is nonetheless recommended.