Efficient visible-light photocatalysts by constructing dispersive energy band with anisotropic p and s-p hybridization states

1. Download : Download high-res image (296KB)
2. Download : Download full-size image

     

The analysis study on nonlinear iterative methods for inverse problems

In this paper, the nonlinear iterative methods, which are different from the classical algorithms, to solve inverse problems are presented. Our methods by denoting some parameters and some properties of the algorithm in both noise and noiseless cases are studied. Finally, the convergence of the sequence generated by the algorithm without noise is discussed.     

iGreen: green scheduling for peak demand minimization

Home owners are typically charged differently when they consume power at different periods within a day. Specifically, they are charged more during peak periods. Thus, in this paper, we explore how scheduling algorithms can be designed to minimize the peak energy consumption of a group of homes served by the same substation. We assume that a set of demand/response switches are deployed at a group of homes to control the activities of different appliances such as air conditioners or electric water heaters in these homes. Given a set of appliances, each appliance is associated with its instantaneous power consumption and duration, our objective is to decide when to activate different appliances in order to reduce the peak power consumption. This scheduling problem is shown to be NP-Hard. To tackle this problem, we propose a set of appliance scheduling algorithms under both offline and online settings. For the offline setting, we propose a constant ratio approximation algorithm (with approximation ratio \(\frac{1+\sqrt{5}}{2}+1\)). For the online setting, we adopt a greedy algorithm whose competitive ratio is also bounded. We conduct extensive simulations using real-life appliance energy consumption data trace to evaluate the performance of our algorithms. Extensive evaluations show that our schedulers significantly reduce the peak demand when compared with several existing heuristics.     

Nonhomogeneous Hemivariational Inequalities with Indefinite Potential and Robin Boundary Condition

We consider a nonlinear, nonhomogeneous Robin problem with an indefinite potential and a nonsmooth primitive in the reaction term. In fact, the right-hand side of the problem (reaction term) is the Clarke subdifferential of a locally Lipschitz integrand. We assume that asymptotically this term is resonant with respect the principal eigenvalue (from the left). We prove the existence of three nontrivial smooth solutions, two of constant sign and the third nodal. We also show the existence of extremal constant sign solutions. The tools come from nonsmooth critical point theory and from global optimization (direct method).     

A transverse crack tip field in bimaterial

The asymptotic field near an interface crack tip is analyzed with the fully nonlinear theory. By dividing the crack tip field into narrowing sectors and an expanding sector, the asymptotic equations for the crack tip field are derived and solved. The singular characters of stress and strain near the crack tip are revealed.     

螺旋槽干气密封微尺度流动场的近似计算及其参数优化

应用PH线性化方法、迭代法,近似求解了螺旋槽内稳态微尺度流动场的非线性雷诺方程,求得了气体动压和速度分布的解析解。继而利用多目标优化方法构建了气膜刚度与泄漏量之比的协调函数,并对该目标函数进行了近似求解,获得了最佳的螺旋槽几何参数值。     

板带轧制过程中的三维接触摩擦模型

为解决压力加工中工具与工件间的接触摩擦问题，根据金属流动对摩擦的反作用，在轧辊和工件之间引入了一层极薄的摩擦单元并将其编入三维弹塑性大变形有限元程序。通过调节摩擦元尺寸厚度和β因子，实现了对薄板轧制过程中间介质的几何尺寸模拟和物理特征模拟。该法不用对摩擦力大小、方向及中性点位置进行假定，通过计算能够得到全部有关信息。     

General coupled solution of anisotropic piezoelectric materials with an elliptic inclusion

In this investigation, the Stroh formalism is used to develop a general solution for an infinite, anisotropic piezoelectric medium with an elliptic inclusion. The coupled elastic and electric fields both inside the inclusion and on the interface of the inclusion and matrix are given. The project supported by the National Natural Science Foundation of China     

AN ALGORITHM FOR SOLVING SPACECRAFT REACHABLE DOMAIN WITH SINGLE-IMPULSE MANEUVERING 1)

航天器轨道机动可达域是表征其在未来时间可能到达空间位置集合的有效方式,对维护航天器在轨安全、改善空间态势感知能力具有重要意义.现有关于可达域计算的方法仍然存在模型复杂、初值敏感性高导致计算效果较差等缺点,因此有必要发展更加简洁有效的可达域包络求解算法.本文基于近心点坐标系建立了基于未来可达位置矢量极值求解的可达域求解模型,首先定义任意指向的矢量描述方法并给出未来该指向位置是否可达的判据;其次,设置转移轨道面内机动方位角,将可达域求解问题转化为当前可达位置矢量方向的单变量极值求解问题,利用极值点处可达域包络面函数梯度需为零的条件确定转移轨道面机动方位角的取值,从而确定航天器的轨道机动可达域;此外根据二体轨道动力学特性,利用包络的对称性减少可达域求解计算量;最后通过蒙特卡洛打靶仿真对提出的可达域求解方法进行仿真验证.结果表明,本文方法对航天器单脉冲轨道机动可达域的计算结果与蒙特卡洛打靶仿真吻合良好,模型更加简洁且计算精度优于现有方法.     

大吨位基桩抗压载荷试验中的锚桩预应力保护技术

竖轴向承载力是桩基础设计的重要参数,现场静载试验是目前确定桩基承载力的主要手段之一。本文依托黄陵—延安段高速公路洛河特大桥试桩工程,通过对原有工程桩施加预应力,形成了以工程桩为锚桩的锚拔体系。加载过程中试桩应力、锚桩应力及桩顶位移测试,结果表明,结合预应力技术,以工程桩作为锚桩构成桩基础静载试验的锚拔体系是可行的,同时提出了施加预应力大小的原则、方法以及确保后期曾作为锚桩的工程桩有足够承载能力应采取的必要措施。