A Maximum Principle via Malliavin calculus for combined stochastic control and impulse control of forward‐backward systems

We consider a combined stochastic control and impulse control problem of forward‐backward systems driven by Lévy processes, where both the system coefficients and the objective performance functional are allowed to be random, non‐Markovian; the information available to the controller is partial information. Applying a Malliavin calculus approach, we derive a maximum principle for this control problem, where the adjoint processes are explicitly represented by the parameters and the states of the system. Finally, we give two examples of applications. © 2015 Chinese Automatic Control Society and Wiley Publishing Asia Pty Ltd     

Game‐Based Valley‐Fill Charging Coordination for Large‐Population Plug‐in Electric Vehicles

Charging coordination of large‐population autonomous plug‐in electric vehicles (PEVs) in the power grid can be formulated as a class of constrained optimization problems. To overcome the computational complexity, a game‐based method is proposed for the charging problems of the PEV population, which is composed of homogeneous subpopulations, such that individuals update their best charging strategies simultaneously with respect to a common electricity price determined by the total demand. To mitigate the oscillation behavior caused by the greedy behavior for the cheap electricity by individuals, a deviation cost is introduced to penalize against the deviation of the individual strategy from the average value of the homogeneous subpopulation. By adopting a proper deviation cost and following a best strategy update mechanism, the game systems may converge to the socially optimal valley‐fill Nash equilibrium. Simulation examples are studied to illustrate the results.     

Insights into virus capsid assembly from non-covalent mass spectrometry

The assembly of viral proteins into a range of macromolecular complexes of strictly defined architecture is one of Nature's wonders. Unraveling the details of these complex structures and the associated self-assembly pathways that lead to their efficient and precise construction will play an important role in the development of anti-viral therapeutics. It will also be important in bio-nanotechnology where there is a plethora of applications for such well-defined macromolecular complexes, including cell-specific drug delivery and as substrates for the formation of novel materials with unique electrical and magnetic properties. Mass spectrometry has the ability not only to measure masses accurately but also to provide vital details regarding the composition and stoichiometry of intact, non-covalently bound macromolecular complexes under near-physiological conditions. It is thus ideal for exploring the assembly and function of viruses. Over the past decade or so, significant advances have been made in this field, and these advances are summarized in this review, which covers the literature up to the end of 2007.     

基于双层调度框架的开放式实时系统非实时应用调度

在开放式实时系统中,多类型实时和非实时应用同时并存,这给系统调度机制带来了新的需求和挑战。对一种开放式实时系统调度机制进行了简单的介绍,指出了非实时应用调度时不可抢占区可能影响系统可调度性,并提出了一种解决方案,弥补了原有调度机制的缺点,完善了开放式实时系统的双层调度框架,保证了开放式实时系统并存多类型实时及非实时应用的可调度性。     

融合多向学习的混沌麻雀搜索算法

对于原始麻雀搜索算法（SSA）在迭代过程中表现出的种群多样性减小,易陷入局部最优等问题,提出一种融合多向学习的混沌麻雀搜索算法（MSSA）。利用Hénon混沌映射初始化种群,增加麻雀种群的多样性,扩大可行解的搜索范围,为全局寻优奠定基础;采用多向学习策略增加麻雀跟随者探索未知领域的机会,平衡算法的局部开发性能和全局搜索能力;当算法陷入局部最优时,引用遗传算法中的变异策略依据动态的变异概率对当前最优个体进行扰动变异;将MSSA算法应用到无线传感器网络节点覆盖优化问题。数值实验结果与Wilcoxon秩和检验结果均表明MSSA算法在收敛精度与收敛速度等方面具有更明显的优势。     

Non‐destructive evaluation of fatigue damage and fatigue crack initiation in type 316 stainless steel by positron annihilation line‐shape and lifetime analyses

Rotating bending fatigue tests were conducted using type 316 stainless steel. The fatigue tests were periodically terminated, and fatigue damage and fatigue crack initiation were non‐destructively and sequentially evaluated by positron annihilation line‐shape and lifetime analyses. The counter‐jig and anticoincidence methods were used for positron annihilation line‐shape and lifetime analyses, respectively, to enhance the analytical precision. The fatigue crack lengths were monitored by a plastic replication technique, and related to the parameters in both analyses. S‐parameter obtained in the line‐shape analysis increased with increasing fatigue damage, while it was difficult to detect fatigue crack initiation and subsequent small fatigue crack growth. That was because the precision of line‐shape analysis was limited. On the other hand, both fatigue damage and fatigue crack initiation were successfully detected by lifetime analysis. Positron annihilation lifetime also increased with increasing fatigue damage, and lifetime was longer at the notch root with fatigue crack than at the smooth section without crack. It was considered that the precision of lifetime analysis was high enough to detect high dislocation density areas at the fatigue crack tips.     

Velocity‐based formulations for standard and quasi‐incompressible hypoelastic‐plastic solids

We present three velocity‐based updated Lagrangian formulations for standard and quasi‐incompressible hypoelastic‐plastic solids. Three low‐order finite elements are derived and tested for non‐linear solid mechanics problems. The so‐called V‐element is based on a standard velocity approach, while a mixed velocity–pressure formulation is used for the VP and the VPS elements. The two‐field problem is solved via a two‐step Gauss–Seidel partitioned iterative scheme. First, the momentum equations are solved in terms of velocity increments, as for the V‐element. Then, the constitutive relation for the pressure is solved using the updated velocities obtained at the previous step. For the VPS‐element, the formulation is stabilized using the finite calculus method in order to solve problems involving quasi‐incompressible materials. All the solid elements are validated by solving two‐dimensional and three‐dimensional benchmark problems in statics as in dynamics. Copyright © 2016 John Wiley & Sons, Ltd.     

Enhanced assessment of ageing phenomena in steel structures based on materials data and non‐destructive testing

The increasing amount of ageing civil steel infrastructure requests an enhanced assessment of this infrastructure in terms of determining its residual fatigue life in a more realistic way than this has been done in the past. Often the relevant materials data for cyclic loading of such an ageing infrastructure is not available and its retrieval turns out to be relatively cumbersome bearing the urgency in data availability and continuous cost pressure in mind. This article addresses different approaches and techniques on how materials data for cyclic loading can be obtained at a fraction of the effort compared to state‐of‐the‐art techniques, considering load increase tests, non‐destructive testing techniques and finally even a stepped bar specimen allowing a complete set of materials data (stress‐strain behaviour and stress‐ and strain‐life curve) to be obtained with a single specimen in the end only. Options for ’digitizing’ materials data evaluation are discussed and some prospect on application of those novel approaches and techniques in damage accumulation assessments on real steel infrastructure is provided.