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1.
《International Journal of Hydrogen Energy》2022,47(58):24592-24609
Hydrogen is gaining increased attention from industries and policymakers in China. However, most of the current demonstration projects in the country have relied on conventional energy sources, including industrial byproduct hydrogen and grey hydrogen produced from fossil fuels. Moreover, strategies and policy frameworks leading to a shift to green or low-carbon hydrogen have neither been explored in-depth nor been identified clearly in the context of China. This study aims at bridging such gaps. Roadmapping techniques enhanced by the Delphi method and SWOT analysis are used to survey hydrogen energy experts from government bodies, industries, and academia to achieve basic agreement on strategically enabling large-scale green hydrogen demonstrations followed by commercialisation in China. The outcome of two rounds of surveys showed that experts' opinions converged on a strategic roadmap with three stages of development. The corresponding policies needed in each stage are evaluated and selected to form a systemic framework. 相似文献
2.
In this paper, limiting factors for increased use of biomethane as a transportation fuel are studied. The aim of this research is to recognize and estimate the limiting factors for biomethane utilization in the transportation sector. The limiting factors are studied by using calculation models from Life cycle perspective and literature reviews. According to the results, the main limiting factors can be classified into the following categories: production potential, technology, economy or policy. For biomethane utilization in Finland, the main limiting factors seem to be the lack of distribution infrastructure in northern parts of the country and the uncertain economical feasibility for agricultural biomass producers and for vehicle owners. From the political perspective, the external costs for petrol operated vehicles are higher than for biomethane operated vehicles. Reductions from the external costs could be used by political decisions as a base to support the growth of biomethane in the transportation sector which could lead to GHG emission reductions. A similar systematic approach can also be used to study limiting factors for other transportation energy systems. 相似文献
3.
This article presents a new approach for solving the Optimal Control Problem (OCP) of linear time-delay systems with a quadratic cost functional. The proposed method can also be used for designing optimal control time-delay systems with disturbance. In this study, the Variational Iteration Method (VIM) is employed to convert the original Time-Delay Optimal Control Problem (TDOCP) into a sequence of nonhomogeneous linear two-point boundary value problems (TPBVPs). The optimal control law obtained consists of an accurate linear feedback term and a nonlinear compensation term which is the limit of an adjoint vector sequence. The feedback term is determined by solving Riccati matrix differential equation. By using the finite-step iteration of a nonlinear compensation sequence, we can obtain a suboptimal control law. Finally, Illustrative examples are included to demonstrate the validity and applicability of the technique. 相似文献
4.
介绍了基于策略的网络管理的概念和当前的研究状况,在策略定义、冲突检测和系统安全问题等方面进行了讨论,提出了一种适合基于策略的网络管理的结构方案,并分析了该方案的合理性。 相似文献
5.
本文提出了求解非线性问题的一种新方法——逐次迭代法,本方法先是给出一个初始近似解,然后将这个近似解进行校正迭代,使之接近于真实解,把一个非线性问题转化为一个线性问题来解决。 相似文献
6.
With the growing size and complexity of power systems, system analysis—such as transients calculation—takes much time. Hence, fast calculation methods are required. Although parallel processing is a hopeful method, there have been difficulties in the parallel solution of linear equations which appear in power-flow calculations by the Newton-Raphson method. This paper aims at the fast calculation of the power-flow problem by means of parallel processing. In order to improve the suitability to the parallel solution of the differential equation in transients calculation, we assume the use of a direct-mapping parallel processing machine to map directly the network of a power system onto a network of processors. Under this assumption, we propose a new parallel-processing-oriented method in which the linear equation is solved by linear iterations between nodes with Aitken acceleration. We simulate the method on three model power systems and compare this Parallel Iterative Method (PIN) with a Parallel Direct Method (PDM) which uses the banded matrix according to the number of operations required. As a result, we can expect that PIM may solve linear equations faster than PDM with m processors, although the PIM might be inferior to the PDM with m × m processors, where m denotes the half-band width of the banded matrix. 相似文献
7.
Business, not technology leaders should manage the change of Information Technology (IT) from a self-contained business support unit of the sixties to a distributed strategic business function of the nineties. Top management should recognize that a good business plan can only be developed and executed through the partnership between the business unit managers and the managers of the financial, the personnel, and the IT resource units. The technical problems associated with the management of IT may again be the easier part of the total management challenge. 相似文献
8.
Xi-Ren CaoAuthor Vitae Zhiyuan RenAuthor Vitae Shalabh BhatnagarAuthor Vitae Michael FuAuthor Vitae Steven MarcusAuthor Vitae 《Automatica》2002,38(6):929-943
We propose a time aggregation approach for the solution of infinite horizon average cost Markov decision processes via policy iteration. In this approach, policy update is only carried out when the process visits a subset of the state space. As in state aggregation, this approach leads to a reduced state space, which may lead to a substantial reduction in computational and storage requirements, especially for problems with certain structural properties. However, in contrast to state aggregation, which generally results in an approximate model due to the loss of Markov property, time aggregation suffers no loss of accuracy, because the Markov property is preserved. Single sample path-based estimation algorithms are developed that allow the time aggregation approach to be implemented on-line for practical systems. Some numerical and simulation examples are presented to illustrate the ideas and potential computational savings. 相似文献
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