Bounded Model Checking Using Satisfiability Solving

The phrase model checking refers to algorithms for exploring the state space of a transition system to determine if it obeys a specification of its intended behavior. These algorithms can perform exhaustive verification in a highly automatic manner, and, thus, have attracted much interest in industry. Model checking programs are now being commercially marketed. However, model checking has been held back by the state explosion problem, which is the problem that the number of states in a system grows exponentially in the number of system components. Much research has been devoted to ameliorating this problem.In this tutorial, we first give a brief overview of the history of model checking to date, and then focus on recent techniques that combine model checking with satisfiability solving. These techniques, known as bounded model checking, do a very fast exploration of the state space, and for some types of problems seem to offer large performance improvements over previous approaches. We review experiments with bounded model checking on both public domain and industrial designs, and propose a methodology for applying the technique in industry for invariance checking. We then summarize the pros and cons of this new technology and discuss future research efforts to extend its capabilities.     

一类奇异分数阶微分方程正解的存在性

研究了一类奇异非线性分数阶微分方程的边值问题.首先给出了该问题的格林函数和其所满足的一些性质,然后利用Krasuoselskii锥上的不动点定理和Leray-Schauder选择定理,建立了该方程至少存在1个正解的充分性条件.     

太阳系行星公转轨道的锥面支架设计研究

依据太阳系行星公转轨道参数将平面曲线扩充成空间曲面,建立异面椭圆变换关系和椭圆锥面方程,分析锥面截线的展开特征,给出锥截面构件的平面加工方法和同顶共焦锥面支架的合成方法。     

渤海底水油田泡沫控水锥技术研究与应用

底水锥进是目前渤海底水油田开发所面临的严峻问题。针对本问题,通过泡沫扫描方法,多孔介质内阻力因子测试、封堵能力评价、提高采收率评价等手段对泡沫生成、稳定性、封堵效果、抗油性等进行了研究。结果表明,泡沫有较好的控水效果,并且确定施工起泡剂质量分数为0．5％,气液体积比为2∶1。该技术在渤海Q HD32-6油田进行了成功应用,实现了良好的控制水锥效果,表明该技术具有良好的应用前景。     

圆锥截线的一致性分析

运用投影柱面对圆锥截线进行分类剖析,解决了圆锥截线及其正投影曲线的系统性和统一性问题。     

时延丢包网络控制系统的分析与控制

针对网络控制系统中同时存在时延和丢包问题,基于零阶保持器的工作机制,将同时受时延和丢包影响的网络控制系统建模为输入带有时延的控制系统,根据李雅普诺夫稳定性理论和时滞系统理论得出控制系统的时滞相关稳定性条件,进一步基于锥补线性化的方法给出控制器的设计方法,有效解决了网络控制系统中同时存在时延和丢包的控制问题。仿真算例表明所提方法的有效性。     

A coaxial pulsed plasma thruster using chemical propellants

Pulsed plasma thrusters (PPTs) have the advantages of mechanical simplicity and robustness compared to other electric propulsion systems. However the thrust power ratio of PPTs is lower than that of other electric propulsion systems. To enhance the thrust performance of the PPT, we propose to use several combustible solid chemicals as coaxial PPT propellants to replace Teflon^® (Polytetrafluoroethylene: PTFE). With the design, the force obtained thermodynamically is expected to augment the PPT thrust power ratio with the help of the chemical energy contained in the propellants. As a result, the thrust power ratio is increased using hydroxyl-terminated polybutadiene-ammonium perchlorate (HTPB-AP)-based propellants compared to the case of ordinary Teflon. The discharge current and voltage waveform does not change even when the propellant is changed. These findings could indicate that the impulse bits by gasdynamic contribution are lager in the case of chemical solid propellants than in the case of Teflon.     

Computationally Efficient Algorithm For Frequency‐Weighted Optimal H∞ Model Reduction

In this paper, a frequency‐weighted optimal H_∞ model reduction problem for linear time‐invariant (LTI) systems is considered. The objective of this class of model reduction problems is to minimize H_∞ norm of the frequency‐weighted truncation error between a given LTI system and its lower order approximation. A necessary and sufficient solvability condition is derived in terms of LMIs with one extra coupling rank constraint, which generally leads to a non‐convex feasibility problem. Moreover, it has been shown that the reduced‐order model is stable when both stable input and output weights are included, and its state‐space data are given explicitly by the solution of the feasibility problem. An efficient model reduction scheme based on cone complementarity algorithm (CCA) is proposed to solve the non‐convex conditions involving rank constraint.     

多目标规划αr-有效解和αr-最优解的充要条件与求解方法

对于有限维Euclid空间中的αr－序类，文[4]讨论了其若干性质，在此基础上文[3]引进了多目标规划αr－有效解和αr－最优解的概念，本文讨论了这些解的一些性质，得到几个充要条件并讨论了求解的方法。     

关于砂土液化判别方法的探讨

本文通过静力触探锥尖阻力与标准贯入击数的回归关系，提出了以《建筑抗震设计规范》（GBJ11－89）为基础的饱和砂土液化静力触探判别方法及液化指数的计算方法。