Boron doping induced electronic reconfiguration of Fe-Nx sites in N-doped carbon matrix for efficient oxygen reduction reaction in both alkaline and acidic media

Developing non-precious metal-based catalysts as the substitution of precious catalysts (Pt/C) in oxygen reduction reaction (ORR) is crucial for energy devices. Herein, a template and organic solvent-free method was adopted to synthesize Fe, B, and N doped nanoflake-like carbon materials (Fe/B/N–C) by pyrolysis of monoclinic ZIF-8 coated with iron precursors and boric acid. Benefiting from introducing B into Fe–N–C, the regulated electron cloud density of Fe-N_x sites enhance the charge transfer and promotes the ORR process. The as-synthesized Fe/B/N–C electrocatalyst shows excellent ORR activity of a half-wave potential (0.90 V vs 0.87 V of Pt/C), together with superior long-term stability (95.5% current density retention after 27 h) in alkaline media and is even comparable to the commercial Pt/C catalyst (with a half-wave potential of 0.74 V vs 0.82 V of Pt/C) in an acidic electrolyte. A Zn-air battery assembled with Fe/B/N–C as ORR catalyst delivers a higher open-circuit potential (1.47 V), specific capacity (759.9 mA h g^?1_Zn at 10 mA cm^?2), peak power density (62 mW cm^?2), as well as excellent durability (5 mA cm^?2 for more than 160 h) compared to those with commercial Pt/C. This work provides an effective strategy to construct B doped Fe–N–C materials as nonprecious ORR catalyst. Theoretical calculations indicate that introduction of B could induce Fe-N_x species electronic configuration and is favorable for activation of OH1 intermediates to promote ORR process.     

Mathematical representation of radiality constraint in distribution system reconfiguration problem

Distribution systems are most commonly operated in a radial configuration for a number of reasons. In order to impose radiality constraint in the optimal network reconfiguration problem, an efficient algorithm is introduced in this paper based on graph theory. The paper shows that the normally followed methods of imposing radiality constraint within a mixed-integer programming formulation of the reconfiguration problem may not be sufficient. The minimum-loss network reconfiguration problem is formulated using different ways to impose radiality constraint. It is shown, through simulations, that the formulated problem using the proposed method for representing radiality constraint can be solved more efficiently, as opposed to the previously proposed formulations. This results in up to 30% reduction in CPU time for the test systems used in this study.     

An interpretative structural modeling based network reconfiguration strategy for power systems

The network reconfiguration is an important stage of restoring a power system after a complete blackout or a local outage. Reasonable planning of the network reconfiguration procedure is essential for rapidly restoring the power system concerned. An approach for evaluating the importance of a line is first proposed based on the line contraction concept. Then, the interpretative structural modeling (ISM) is employed to analyze the relationship among the factors having impacts on the network reconfiguration. The security and speediness of restoring generating units are considered with priority, and a method is next proposed to select the generating unit to be restored by maximizing the restoration benefit with both the generation capacity of the restored generating unit and the importance of the line in the restoration path considered. Both the start-up sequence of generating units and the related restoration paths are optimized together in the proposed method, and in this way the shortcomings of separately solving these two issues in the existing methods are avoided. Finally, the New England 10-unit 39-bus power system and the Guangdong power system in South China are employed to demonstrate the basic features of the proposed method.     

岩性指示曲线重构及其在储层预测中的应用

大牛地上古生界岩性气藏主要发育在三角洲分流河道沉积的下石盒子组、海陆交互沉积的山西组及以潮坪相沉积为主的太原组,储层是储集性能较差的致密砂岩,平均孔隙度小于10％,渗透率小于1×10-2μm2,储层单层厚度一般小于10 m,砂体横向连通性较差。由于低孔、低渗特征导致储层与围岩的波阻抗差异微弱,用地震资料进行储层预测困难。为此,针对大牛地石板太工区优质储层的岩性特征和测井响应特征进行了测井综合分析,利用对岩性粒度敏感的自然伽马曲线,以及对岩性粒度响应频率较低,且与波阻抗有较好对应关系的中子曲线重构了岩性指示曲线。岩性指示曲线不仅可以有效地识别优质砂体,划分不同岩性,为地震、测井信息结合的岩性反演建立桥梁,同时也为反演结果识别气层打下了基础。利用岩性指示曲线、波阻抗和电阻率曲线进行的地震、测井联合反演技术在石板太工区取得了较好的效果,同时,对石板太工区下石盒子组盒2段、山2段进行了储层和含气性预测,划分了有利含气区带,部署的2口开发井和1口探井有2口井见气,其中1口井获高产气流。     

无人机自主编队飞行控制的技术问题

从未来无人机的性能需求出发，详细描述了无人机编队飞行的功能特点和核心技术。根据无人机的任务要求，将编队飞行分为作战编队、侦察编队和混合协同编队，同时研究了编队飞行控制的关键技术，并对无人机编队重构技术进行了探讨和分析。     

SFTMP——一个实现软件容错的多处理机系统

多版本软件通过设计相异性实现了软件容错。为了对这种方法进行研究，我们的课题实现了一个三版本软件系统，称之为SFTMP（SoftwareFault－TolerantMultiProcessor）。本文描述了SFTMP的硬件结构和软件执行支持环境，该环境包括同步、表决和监控功能、版本间的通讯及故障的恢复和重构。     

Fault diagnosis in reconfigurable VLSI and WSI processor arrays

A systematic efficient fault diagnosis method for reconfigurable VLSI/WSI array architectures is presented. The basic idea is to utilize the output data path independence among a subset of processing elements (PEs) based on the topology of the array under test. The divide and conquer technique is applied to reduce the complexity of test application and enhance the controllability and observability of a processor array. The array under test is divided into nonoverlapping diagnosis blocks. Those PEs in the same diagnosis block can be diagnosed concurrently. The problem of finding diagnosis blocks is shown equivalent to a generalizedEight Queens problem. Three types of PEs and one type of switches, which are designed to be easily testable and reconfigurable, are used to show how to apply this approach. The main contribution of this paper is an efficient switch and link testing procedure, and a novel PE fault diagnosis approach which can speed up the testing by at leastO(V^1/2) for the processor arrays considered in this paper, where V is the number of PEs. The significance of our approach is the ability to detect as well as to locate multiple PE, switch, and link faults with little or no hardware overhead.     

Run-time generation of partial FPGA configurations

This paper presents and evaluates a method of generating partial bitstreams at run-time for dynamic reconfiguration of sections of an FPGA. The method is intended for use in adaptive embedded systems that employ run-time reconfiguration to achieve high flexibility and performance. The proposed approach combines partial bitstreams of coarse-grained components to produce a new partial bitstream implementing a given circuit netlist. Topological sorting of the netlist is used to determine the initial positions of individual components, whose placement is then improved by simulated annealing. Connection routing is done by a breadth-first search of the reconfigurable area based on a simplified resource model of the reconfigurable fabric. The desired partial bitstream is constructed by merging together the default bitstream of the reconfigurable area, the relocated partial bitstreams of the components, and the configurations of the switch matrices used for routing. The approach is embodied in a code library that applications can use to create new bitstreams at run-time. For the members of a set of 29 benchmarks (both synthetic and application-derived) having between five and 41 components, the complete process of bitstream generation takes between 8 s and 35 s when running on an embedded PowerPC 405 microprocessor clocked at 300 MHz.     

Fault tolerance in multiprocessor systems

Multiprocessor systems which afford a high degree of parallelism are used in a variety of applications. The extremely stringent reliability requirement has made the provision of fault-tolerance an important aspect in the design of such systems. This paper presents a review of the various approaches towards tolerating hardware faults in multiprocessor systems. It emphasizes the basic concepts of fault tolerant design and the various problems to be taken care of by the designer. An indepth survey of the various models, techniques and methods for fault diagnosis is given. Further, we consider the strategies for fault-tolerance in specialized multiprocessor architectures which have the ability of dynamic reconfiguration and are suited tovlsi implementation. An analysis of the state-of-the-art is given which points out the major aspects of fault-tolerance in such architectures.     

基于双种群CSO算法重构的含DG配网故障恢复

为兼顾配网故障恢复的快速性和最优性,提出一种基于重构的分级响应故障恢复方法,并应用双种群纵横交叉(crisscross optimization algorithm,CSO)算法寻求重构方案。首先在故障隔离后利用启发式规则进行局部重构,以较少的开关动作次数快速恢复配网连通性。然后在局部重构后有安全指标越限时,利用改进的双种群二进制纵横交叉算法在可行域内搜索最优解进行全局重构。若全局重构后安全指标依然越限,按负荷重要性指标切除部分非关键负荷,恢复配电网安全运行。最后,改进的PG&E配电系统仿真结果验证了该方法的可行性和有效性。