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1.
Impact of communication time delays on
combined LFC and AVR of a multi-area
hybrid system with IPFC-RFBs coordinated
control strategy
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In this paper, the impact of communication time delays (CTDs) on combined load frequency control (LFC) and
automatic voltage regulation (AVR) of a multi-area system with hybrid generation units is addressed. Investigation
reveals that CTDs have significant effect on system performance. A classical PID controller is employed as a
secondary regulator and its parametric gains are optimized with a differential evolution - artificial electric field
algorithm (DE-AEFA). The superior performance of the presented algorithm is established by comparing with
various optimization algorithms reported in the literature. The investigation is further extended to integration of
redox flow batteries (RFBs) and interline power flow controller (IPFC) with tie-lines. Analysis reveals that IPFC and
RFBs coordinated control enhances system dynamic performance. Finally, the robustness of the proposed control
methodology is validated by sensitivity analysis during wide variations of system parameters and load. 相似文献
2.
Vydyanathan Naga Krishnamoorthy Sriram Sabin Gerald M. Catalyurek Umit V. Kurc Tahsin Sadayappan Ponnuswamy Saltz Joel H. 《Parallel and Distributed Systems, IEEE Transactions on》2009,20(8):1158-1172
Complex parallel applications can often be modeled as directed acyclic graphs of coarse-grained application tasks with dependences. These applications exhibit both task and data parallelism, and combining these two (also called mixed parallelism) has been shown to be an effective model for their execution. In this paper, we present an algorithm to compute the appropriate mix of task and data parallelism required to minimize the parallel completion time (makespan) of these applications. In other words, our algorithm determines the set of tasks that should be run concurrently and the number of processors to be allocated to each task. The processor allocation and scheduling decisions are made in an integrated manner and are based on several factors such as the structure of the task graph, the runtime estimates and scalability characteristics of the tasks, and the intertask data communication volumes. A locality-conscious scheduling strategy is used to improve intertask data reuse. Evaluation through simulations and actual executions of task graphs derived from real applications and synthetic graphs shows that our algorithm consistently generates schedules with a lower makespan as compared to Critical Path Reduction (CPR) and Critical Path and Allocation (CPA), two previously proposed scheduling algorithms. Our algorithm also produces schedules that have a lower makespan than pure task- and data-parallel schedules. For task graphs with known optimal schedules or lower bounds on the makespan, our algorithm generates schedules that are closer to the optima than other scheduling approaches. 相似文献
3.
Naga Vydyanathan Umit Catalyurek Tahsin Kurc Ponnuswamy Sadayappan Joel Saltz 《Parallel Computing》2011,37(10-11):694-712
Scheduling, in many application domains, involves optimization of multiple performance metrics. For example, application workflows with real-time constraints have strict throughput requirements and also desire a low latency or response time. In this paper, we present a novel algorithm for the scheduling of workflows that act on a stream of input data. Our algorithm focuses on the two performance metrics, latency and throughput, and minimizes the latency of workflows while satisfying strict throughput requirements. We also describe steps to use the above approach to solve the problem of meeting latency requirements while maximizing throughput. We leverage pipelined, task and data parallelism in a coordinated manner to meet these objectives and investigate the benefit of task duplication in alleviating communication overheads in the pipelined schedule for different workflow characteristics. The proposed algorithm is designed for a realistic bounded multi-port communication model, where each processor can simultaneously communicate with at most k distinct processors. Experimental evaluation using synthetic benchmarks as well as those derived from real applications shows that our algorithm consistently produces lower latency schedules that meet throughput requirements, even when previously proposed schemes fail. 相似文献
4.
5.
Insulating and Other Physical Properties of CoO‐Doped Zinc Oxyfluoride‐Borate Glass‐Ceramics
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Padamati Naresh Goli Naga Raju Yerramreddy Gandhi Michal Piasecki Nalluri Veeraiah 《Journal of the American Ceramic Society》2015,98(2):413-422
Zinc oxy fluoro borate glasses mixed with different concentrations of CoO (ranging from 0 to 2.0 mol%) are synthesized and subsequently crystallized. The scanning electron microscopy pictures have exhibited crystallinity. Differential scanning calorimetric studies have indicated that the prepared samples consist of multiple crystal phases. The X‐ray diffraction patterns have indicated that the glass‐ceramic samples are composed of αZn(BO2)2, (Zn)3(BO3)2, CoF2, CoF3, Co3FB7O13, ZnCo2O4, Co3O4 crystalline phases. The optical absorption and photoluminescence studies have indicated that there is a gradual increase of tetrahedral cobalt ion concentration with increase of CoO concentration in the glass network. IR spectroscopic studies have pointed out increased degree of polymerization of the zinc oxy fluoro borate glass network with increase of CoO content. The analysis of results of dielectric properties indicated increase of insulating strength of the glass‐ceramics with increase of CoO content. Finally, the dielectric breakdown strength of the samples is measured at room temperature in air medium and it is found to increase from 12.9 to 19.2 kV/cm with increase of CoO from 0.2 to 2.0 mol%. The reasons for such increase of breakdown strength are discussed quantitatively in terms of dielectric parameters with aid of data on spectroscopic properties. 相似文献
6.
Differential thermal analysis (DTA) and thermogravimetry (TG) methods have been developed to evaluate the thermal and thermooxidation stability of different lubricating oils. Measurements are carried out either by heating the oil sample at a constant rate (direct programme) or by keeping it at a fixed high temperature (isothermal programme). Oxygen at a constant flow rate is used for thermooxidation measurements. Tested samples included different viscosity grades: neutral base oils, unadditivated lubricating oil blends, and industrial oils. The mechanism of thermal decomposition for ZDDP and the estimation of its optimum concentration was also considered. 相似文献
7.
Lakshmi Krishnasamy Rama Mohan Rao Arumulla Gopalakrishnan Naga 《Structure and Infrastructure Engineering》2018,14(10):1412-1431
An approach to enhance the sensitivity of the damage index using the prediction errors of autoregressive – autoregressive exogenous models by augmenting Singular Spectrum Analysis (SSA) to detect and locate minor damage is presented. Numerical simulation studies are carried out by considering a simply supported beam with single and multiple cracks. An experimental study on a reinforced cement concrete beam has been carried out to validate the technique using different levels of damage. The studies emphasise that the SSA improves the sensitivity of the damage index for detection and also localisation, handling environmental/operational variability and measurement noise. 相似文献
8.
9.
Samples of composites of graphene with indium or indium-gallium alloy as the matrix were prepared by a process of spreading
exfoliated graphene oxide on the foils, repeatedly folding and rolling. The foils were intermittently annealed and the process
repeated by addition of more graphene oxide. Indium flux was used to remove any indium or gallium oxide. The samples were
characterized by x-ray diffraction, and optical and scanning electron microscopy (SEM). Electrical resistivity and temperature
coefficient of resistance (TCR) were measured using a four-probe method in the temperature range of 260 K to 340 K, and the
results were used to determine the volume fraction of graphene from effective mean-field analysis. The volume fraction of
graphene remained between 0.11 and 0.14 in samples of In with graphene and between 0.12 and 0.13 in samples of In-Ga with
graphene. The results indicate that the electrical resistivity and the TCR of the composite were reduced by the addition of
graphene. The resistivity of graphene remained between 1.19 × 10−6 ohm cm and 1.87 × 10−6 ohm cm in all samples and was thus almost independent of the matrix composition. The electrical resistivity of graphene was
found to be an order of magnitude smaller than that of indium or the indium-gallium alloy. 相似文献
10.
Polyethylene containing 1,3-cyclopentane units in the main chain was synthesized by ring-opening metathesis copolymerization of cyclopentene (CPE) or cyclooctene with norbornene (NB) following hydrogenation reaction. The copolymer with cis-1,3-cyclopentane units was obtained in good yield. The resulting copolymers showed multiple melting points. Temperature-rising elution fractionation of the copolymers elucidated a broad distribution of the copolymer composition. WAXD and FT-IR analyses of the copolymers showed existence of hexagonal crystal in hydrogenated poly(CPE-co-NB). 相似文献