After conventional waterflood processes the residual oil in the reservoir remains as a discontinuous phase in the form of oil drops trapped by capillary forces and is likely to be around 70% of the original oil in pla...
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ISBN:
(纸本)9781555639884
After conventional waterflood processes the residual oil in the reservoir remains as a discontinuous phase in the form of oil drops trapped by capillary forces and is likely to be around 70% of the original oil in place (OOIP). The EOR method so-called alkaline-surfactant-polymer (ASP) flooding has been proved to be effective in reducing the oil residual saturation in laboratory experiments and field projects through reduction of interfacial tension and mobility ratio between oil and water phases. A critical step to make ASP floodings more effective is to find the optimal values of design variables that will maximize a given performance measure (e.g. net present value, cumulative oil recovery) considering a heterogeneous and multiphase petroleum reservoir. Previously reported works using reservoir numerical simulation have been limited to sensitivity analyses at core and field scale levels because the formal optimization problem includes computationally expensive objective function evaluations (field scale numerical simulation). The proposed methodology estimates the optimal values for a set of design variables (slug size and concentration of the chemical agents) to maximize the cumulative oil recovery from a heterogeneous and multiphase petroleum reservoir subject to an ASP flooding. The surrogate-based optimization approach has been shown to be useful in the optimization of computationally expensive simulation-based models in the aerospace, automotive, and oil industries. In this work we have extended this idea along two directions: i) using multiple surrogates for optimization, and ii) incorporating an adaptive weighted average model of the individual surrogates. The proposed approach involves the coupled execution of a global optimization algorithm and fast surrogates (ì.e. based on Polynomial Regression, Kriging, and a Weighted Average Model) constructed from field scale numerical simulation data. The global optimization program implement the DIRECT algorithm a
A suitable workload distribution is essential for obtaining good performance on software distributed shared memory (DSM) systems. The methods proposed by the past DSM researches only simply distribute program threads ...
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ISBN:
(纸本)9780780384309
A suitable workload distribution is essential for obtaining good performance on software distributed shared memory (DSM) systems. The methods proposed by the past DSM researches only simply distribute program threads in accordance with the CPU power of the individual processors or the data sharing within the DSM applications. These methods expected the minimal program execution time by reducing computation cost and communication cost. However, memory access costs also play a significant role in determining the program performance. If a processor lacks sufficient memory space to cache all of the data required by the working threads, then it will suffer from a series of page faults and will need to execute consecutive page replacements while executing its threads. Although the threads will be able to complete their tasks, their execution will inevitably be delayed by the latency associated with executing the page replacements. To resolve this problem, this paper is dedicated to involving memory resource consideration into workload distribution for software DSM systems. The present results confirm the importance of considering memory resources when addressing the workload distribution of DSM systems. It is shown that the proposed method is more effective than previous methods which considered only CPU resource or memory resource.
In industrial practice, engineers and engineering technologists often collaborate on solving problems. Yet, this collaboration rarely occurs in an educational setting. Queen's University and Fleming College have p...
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TFRC is an equation-based rate control scheme originally developed for media streaming over wired networks. When applied to the wireless networks, it suffers from performance degradation. In this paper, we propose a L...
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We present an active network-based approach in order to improve the performance of mobile transactions. This approach employs preemptive resume scheduling mechanism which reduces queuing delays involved in the process...
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ISBN:
(纸本)0769520510
We present an active network-based approach in order to improve the performance of mobile transactions. This approach employs preemptive resume scheduling mechanism which reduces queuing delays involved in the processing of mobile transactions at each network node. Such reduction of queuing delay significantly improves performance of mobile transactions given the heavy network traffic and the lower network bandwidth. We have conducted several experiments using analytical modelling approach in order to determine the impact of priority scheduling mechanism on the performance of mobile transactions. Experiments show significant performance improvements of the proposed approach over existing approaches of mobile transactions. It has also been shown that the proposed approach is robust in that it can be applied to improve the performance of current mobile transaction approaches.
The analytical design procedure of low-sensitivity, low-power, low-pass (LP) 2nd-and 3rd-order class-4 active-RC allpole filters, using impedance tapering, has already been published [1][2]. In this paper the desensit...
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The analytical design procedure of low-sensitivity, low-power, low-pass (LP) 2nd-and 3rd-order class-4 active-RC allpole filters, using impedance tapering, has already been published [1][2]. In this paper the desensitisation using impedance tapering is applied to the design of LP 4 th-order filters. The numerical design procedure was performed by Newton's iterative method. Analytically designed unity-gain LP 4 th-order filters [3] can provide initial values for Newton's method. The sensitivities of a filter transfer function to passive component tolerances, as well as active gain variations are examined by the Schoeffler sensitivity and Monte Carlo PSpice simulation. Butterworth and Chebyshev 0.5dB filter examples illustrate the design method.
Ad-hoc networks are perceived as communities of autonomous devices that interconnect with each other. Typically, they have dynamic topologies and cannot rely on a continuous connection to the Internet. Users' devi...
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Empirical experience and observations have shown us when powerful and highly tunable classifiers such as maximum entropy classifiers, boosting and SVMs are applied to language processing tasks, it is possible to achie...
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