RC4 has proved itself as robust enough and is trusted by many organizations. A number of researchers claimed that though this stream cipher is simple, fast, easy to implement, it has some weakness and bias in its inte...
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ABB's new DCT880 is a thyristor power controller for heating applications whose integrated power optimization algorithms reduce costs by reducing peak power demand. This is done fully automatically without affecti...
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ABB's new DCT880 is a thyristor power controller for heating applications whose integrated power optimization algorithms reduce costs by reducing peak power demand. This is done fully automatically without affecting the production process or schedule. The main component is an optimization suite that runs on the DCT880 without the need for further supervisory equipment like additional programmable logic controllers. The key to optimization is a microtime energy scheduling algorithm. This shifts the periods in which energy is consumed by amounts small enough that the heating process is not affected. Depending on the load type, each DCT880 can control up to three loads that are independent of each other. Many configurations are possible, such as several single-phase, delta, star, multi-tap, open delta, etc. If more than three loads are to be controlled, one (standard) DCT880 will act as master and will be responsible for the power optimization calculations A special feature of DCT880's power optimization is its handling of mid-load situations. The DCT880 optimization solution reduces the customer's process energy costs. It also helps to enforce grid stability and power quality. It is easy to use as it dispenses with hard-to-understand tuning parameters, which means commissioning and maintenance can be done without the aid of specialists.
scheduling algorithm and cache replacement algorithm are two important aspects in a web server cluster, which affect, even determine, the performance of the cluster system. However, their performance depends on client...
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scheduling algorithm and cache replacement algorithm are two important aspects in a web server cluster, which affect, even determine, the performance of the cluster system. However, their performance depends on client access pattern and some key system parameters to a large extent. In this paper, we design and implement a trace-driven web server cluster simulation platform based on JavaSim, called WSCSim, to evaluate the two kinds of algorithms. The algorithms are directly written in Java, so complicated algorithms can be simulated. In the platform, users are allowed to add new trace parsers to support different trace formats, and can utilise the timer and hook component to collect related information and then calculate the performance indexes they are interested in. Especially, the platform adopts loosely-coupled component architecture to facilitate extension, and all the extensible components are plug and play (PnP). All the components and their parameters can be configured in a configuration file of XML format. Two simulation application scenarios show the feasibility and validity of WSCSim.
In response to two decades of development in structured dense matrix algorithms and a vast number of research codes, we present designs and progress towards a codebase that is abstracted over the primary domains of re...
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Aiming at improving the system uplink transmitting and fairness performance, a novel grouping based double proportional fair schedule algorithm is proposed. By dividing users into several groups, computation complexit...
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To support mobility, mobile devices are powered by batteries with limited energy. Energy efficiency becomes one of the most important issues in wireless networks. Based on IEEE 802.11 infrastructure wireless LANs, we ...
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Two distinct characteristics of grid computing systems are resource heterogeneity and availability variation. There are many well-designed scheduling algorithms proposed for heterogeneous computing systems. However, t...
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Two distinct characteristics of grid computing systems are resource heterogeneity and availability variation. There are many well-designed scheduling algorithms proposed for heterogeneous computing systems. However, the availability variation is seldom considered in developing scheduling ongoing applications on a grid. In this paper, two scheduling algorithms called AMOF and AMOSF are proposed. Both of them consider availability variation as well as resource heterogeneity while scheduling an ongoing workflow application on the grid. An experiment has been conducted to demonstrate that AMOF and AMOSF algorithms outperform the well-known scheduling algorithms: GS and HEFT in most of the cases.
In this paper, we consider a coordinated multipoint (CoMP) dynamic cell selection (DCS) scheme in order to improve performances of sleeping cell users. According to this DCS, packets for user equipments (UEs) in a sle...
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In this paper, we consider a coordinated multipoint (CoMP) dynamic cell selection (DCS) scheme in order to improve performances of sleeping cell users. According to this DCS, packets for user equipments (UEs) in a sleeping cell are randomly forwarded to the potential active base stations (BSs) by the packet serving gateway (PSG) and UEs in the sleeping cell dynamically select these active BSs to be served in each time slot. We develop an analytical model using the fork/join (F/J) queuing model that considers the time varying nature of the channels, the channel scheduling mechanism, partial channel quality feedback, bursty packet arrivals and the packet scheduling mechanism. The developed analytical model can be used to measure various packet level performance parameters such as packet loss probability (PLP) and queuing delay while accounting for out-of-order packet delivery. Presented numerical results show that the considered CoMP DCS scheme provides significant performance improvement compared to the traditional fixed cell selection.
The worldwide markets for Machine-type Communication (MTC) over cellular networks are expected to grow in the incoming years. However, since MTC is quite different than existing Human-type Communication (HTC), it pose...
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The worldwide markets for Machine-type Communication (MTC) over cellular networks are expected to grow in the incoming years. However, since MTC is quite different than existing Human-type Communication (HTC), it poses significant challenges to the cellular networks. Large number of MTC devices are anticipated to be operating in the future Long Term Evolution (LTE) networks, bringing several service requirements. The LTE standard suffers from excessive Physical Downlink Control Channel (PDCCH) overhead associated with the radio resource allocation method for small, sporadic traffic per terminal which is the nature of Machine-to-Machine (M2M) traffic. The rigid Quality of Service (QoS) support framework of LTE for voice and data services also fails to address specific QoS requirements of M2M traffic. This paper focuses on describing the impact of M2M traffic on the performance of the HTC users in LTE Frequency Division Duplexing (FDD) uplink. Simulation results show the impact of M2M traffic on the performance of different types of Human-to-Human (H2H) services (Voice-over-IP (VoIP), video and CBR), when using a QoS-aware packet scheduling. Although MTC in LTE networks impacts HTC, the utilization of a semi-persistent scheduling scheme to VoIP traffic can reduce such impact.
Energy constrained devices, operating on short-range wireless networking standards such as IEEE802.15.4 and IEEE802.11x, are expected to be deployed for the IoT (Internet of Things) applications. However, co-located d...
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Energy constrained devices, operating on short-range wireless networking standards such as IEEE802.15.4 and IEEE802.11x, are expected to be deployed for the IoT (Internet of Things) applications. However, co-located deployment of such devices based on different standards using the same 2.4 GHz license free Industrial, Scientific and Medical (ISM) spectrum, introduces coexistence issues, specifically intra-and inter cluster interference. The latter would create a much more adverse impact on these devices than the former, resulting in significant performance degradation. To overcome this problem, we propose a novel area packet scheduler that allows co-located 802.15.4 and 802.11 devices to share the transmission channel and coexist with minimal inter-cluster interference any inter cluster interference. A new OPNET simulation model was developed to evaluate the performance of this scheduler. Simulation results show that the packet scheduler can mitigate the coexistence problem while maintaining high throughput and low end-to-end delay, thereby increasing the overall network QoS.
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