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Prefetching control is a vital operation for the On-demand interactive systems where the instantaneous response is the crucial factor for the system success. The controller in such type of interactive system operates in an uncertain environment and makes sequences of decisions with long and short term stochastic effects. The difficulty, then, is to determine at every system state which contents to...
The performance requirements and amount of work of an I/O workload affect the number of storage devices and the run time needed by the workload, and should be included in the calculation of the cost or energy consumption of storage devices. This paper introduces models to calculate the cost and energy consumption of storage devices for running a variety of workloads, categorized by their dominant...
Scalable video coding is used with peer to peer networks to minimize the upload bandwidth of peers and to reduce the effects of churn. We have formulated an NP complete optimization problem to describe the upload bandwidth at each peer. We proposed an approximation algorithm to solve this problem. Furthermore, seed servers are deployed in the network to overcome the upload bandwidth limitation at...
A fully functional hybrid cloud solution requires a placement service to automatically decide whether an application should be deployed on premise, in a public cloud, or across private and public clouds. Such a service must consider application structure and communication patterns, application affinity requirements, which usually result from data protection rules, and deployment costs. In this paper,...
Reliability is a critical metric in the design and development of scale-out data storage clusters. A general multiway replication-based declustering scheme has been widely used in enterprise large-scale storage systems to improve the I/O parallelism. Unfortunately, given an increasing number of node failures, how often a cluster starts losing data when being scaled-out is not well investigated. In...
This paper describes the operation and control of Modular Multilevel Converter (MMC). The converter current controllers were designed with different bandwidth ranges. Different operating conditions for the controllers led to different responses and its impact was evaluated. Simulation results of a 5MW grid connected to the MMC illustrate the good dynamic and steady state responses.
One of the challenge issues in network virtualization is the efficient mapping of a virtual network (VN) onto a shared substrate network. The VN mapping problem has been addressed by various researchers. However, these solutions and associated algorithms are only efficient for building unicast service oriented virtual networks, and are not applicable to multicast service oriented VNs. Furthermore,...
The linear sampling method is a qualitative inverse scattering technique that does not rely on any geometric priors and is more immune to model mismatches than non-linear optimization techniques. Unfortunately it is prone to instability especially with under-sampled aperture data. This paper presents a multi-frequency LSM reconstruction method that aims to mitigate such instability and provide increased...
Propagation of short infrared/optical pulses, described by mutual coherence function, in a dilute random medium consisting of large (compared to the wavelength) non-absorbing scatterers is analyzed in the framework of radiative-transfer equation (RTE). A novel and rigorous approach based on analytic complex-contour integration of numerically determined cut and pole singularities of the RTE solution...
In this paper we present a new approach for the measurement of multiple digital holograms at different positions in space that can be combined to one high resolution hologram. The reconstruction is based on a phase shifting approach, where the CCD sensor and the reference wave are moved simultaneously along different positions in x and y. An inclination of the reference wave induces a phase shift...
Modularity and hierarchical-based design are crucial features that need to be supported in complex embedded systemscharacterized by multiple applications with timing requirements.Resource reservation is a powerful scheduling mechanism forachieving such goals and providing temporal isolation amongdifferent real-time applications. When different applications sharemutually exclusive resources, a precise...
Communication is a vital part of computer systems today. One current problem is that computational capacity is growing faster than the bandwidth of interconnected computers. Maximising performance is a key objective for industries, both on new and existing software systems, which further extends the need for more powerful systems at the cost of additional communication. Our contribution is to let...
High resolution imaging is an important trend for SAR. The wide bandwidth signal is a must for high resolution. The error of traditional model based on the narrow bandwidth system may be inevitable for high resolution imaging. In this paper, a general SAR echo model is derived for the wide bandwidth system, and we also get the error factor between the traditional and general model. By simulating the...
In this paper, a novel control solution is proposed and validated, for the decoupling control of variable geometry turbine (VGT) and exhaust gas recirculation (EGR) system in diesel engines. The cross-coupling and dynamics variation are lumped together as total disturbance, estimated and cancelled in real time by active disturbance rejection control (ADRC). The static and dynamic feed-forward controllers...
Hybrid supply modulator consisting of parallel operation of a linear amplifier and a switching amplifier is often used in envelope tracking power amplifier systems to improve power efficiency at different back-off levels. This paper features a detailed analysis of current slew rate of hybrid supply modulator, which is lacking in many papers. Based on this slew rate analysis, one new methodology to...
An analysis method based on vector triangle and vector locus is introduced in this paper. By using vector triangles, a set of quantities generally used in feedback theory can be intuitively visualized, which is impossible by using other theories. The vector locus records the evolvement of the vector triangle versus frequency in polar coordinates, and combines the magnitude and phase plot together...
With network virtualization more and more popular, how to protect the virtual networks (VNs) from a single substrate link failure is increasingly important. Existing protection schemes like dedicated backup and shared backup, suffer from high resource cost and delayed recovery, respectively. To offer instantaneous recovery with less redundant resource, in this paper, we propose a coding-aware VN mapping...
This paper discusses the networked predictive control with communication delay and data loss in feedback channel under limit-bandwidth through a single value. A networked predictive control scheme is used to actively compensate for the communication delay and data loss. Based on the analysis of the closed-loop networked predictive control systems, a design strategy and detail steps is proposed. The...
Infrastructure-as-a-Service (IaaS), which is offered by cloud computing, has focused on providing computing and storage resources, considering network mostly as a required communication accessory and not as a resource itself. In other words, the ability to define network resources (e.g. routing/switching elements, bandwidth, delay) is still very limited. However, the need to have more robust solutions...
In cloud environments, resources can be requested on-demand when they are needed. A cloud management system is responsible for determining which physical machines are responsible for processing the requests. The problem of determining which servers are used for which services is referred to as the Cloud Application Placement Problem (CAPP), and multiple criteria such as cost and number of migrations...
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