一种基于扩展不完全Kripke结构的三值逻辑模型检测方法

多值模型检测是解决形式化验证中状态爆炸问题的一种重要方法,三值模型检测是多值模型检测的基础,其中如何检验不确定状态的真值是一难点。针对不确定状态检验,提出了一种模型检测方法,首先对不完全Kripke结构PKS进行了扩展,然后在扩展后的模型上给出了检测不确定状态真值的方法,最后给出了基于扩展不完全Kripke结构的三值逻辑模型检测算法。与已有的三值逻辑模型检测算法相比,该算法降低了算法复杂度,完善了对于不确定或不一致信息的处理,从而增强了三值逻辑模型检测的实用性。     

运用SPIN对开放授权协议OAuth 2.0的分析与验证

OAuth 2.0协议是一种开放授权协议,主要用于解决用户账号关联与资源共享问题。但是,其弱安全性导致各网络公司海量用户信息泄露,且OAuth 2.0传输数据采用的https通道效率低下,成为黑客攻击对象。提出采用http通道传输OAuth 2.0协议数据,基于Promale语言及Dolev-Yao攻击者模型对OAuth 2.0协议建模,运用SPIN进行模型检测。形式化分析结果表明,采用公钥加密体系对OAuth 2.0协议进行加密不安全。上述建模方法对类似的授权协议形式化分析有重要借鉴意义。     

一种低噪声分离装置研究

低噪声分离装置的主要功能是实现段间连接和可靠的低噪声分离。其工作原理主要为杠杆原理,主体采用完全机械结构,执行机构由小型机电结合件限位控制,在采用了适当的降噪措施后,其动作可靠,静音效果良好。     

Novel ultra‐compact two‐dimensional waveguide‐based metasurface for electromagnetic coupling reduction of microstrip antenna array

A novel ultracompact two‐dimensional (2D) waveguide‐based metasurface is proposed herein and applied for the first time to reduce mutual coupling in antenna array for multiple‐input multiple‐output applications. The unit cell of the proposed 2D waveguide‐based metasurface is ultracompact (8.6 mm × 4.8 mm, equal to λ₀/14.2 × λ₀/25.5) mainly due to the symmetrical spiral lines etched on the ground. The metasurface exhibits a bandgap with two transmission zeros attributing to the negative permeability in the vicinity of magnetic resonance and the negative permittivity in the vicinity of electric resonance. Taking advantage of these two features, a microstrip antenna array is then designed, fabricated, and measured by embedding an 8 × 1 array of the well‐engineered 2D waveguide‐based metasurface elements between two closely spaced (9.2 mm, equal to λ₀/13.3) H‐plane coupled rectangular patches. There is good agreement between the simulated and measured results, indicating that the metasurface effectively reduces antenna mutual coupling by more than 11.18 dB and improves forward gain. The proposed compact structure has one of the highest reported decoupling efficiencies among similar periodic structures with comparable dimensions. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:789–794, 2015.     

Continuum electrostatic approach for evaluating positions and interactions of proteins in a bilayer membrane

Orientations of proteins in the membranes are crucial to their function and stability. Unfortunately the exact positions of these proteins in the lipid bilayer are mostly undetermined. Here, the spatial orientation of membrane proteins within the lipid membrane was evaluated using a Poisson–Boltzmann solvent continuum approach to calculate the electrostatic free energy of the protein solvation at various orientations in an implicit bilayer. The solvation energy was obtained by computing the difference in electrostatic energies of the protein in water and in lipid/water environments, treating each as an implicit solvent model. The optimal position of transmembrane proteins (TMP) in a lipid bilayer is identified by the minimum in the “downhill” pathway of the solvation energy landscape. The energy landscape pattern was considerably conserved in various TMP classes. Evaluation of the position of 1060 membrane proteins from the orientations of proteins in membranes (OPM) database revealed that most of the polytopic and β-barrel proteins were in good agreement with those of the OPM database. The study provides a useful scheme for estimating the membrane solvation energy made by lipid-exposed amino acids in membrane proteins. In addition, our results tested with the bacterial potassium channel model demonstrated the potential usefulness of the approach in assessing the quality of membrane protein models. The present approach should be applicable for constructing transmembrane proteins–lipid configuration suitable for membrane protein simulations and will have utility for the structural modeling of membrane proteins.     

基于Karnopp摩擦的柔性滑移铰的建模与仿真

对含Karnopp摩擦的柔性滑移铰系统进行动力学建模和仿真.将滑移铰中的滑块视为柔性体,滑道视为刚性接触面,考虑滑道与滑块之间的间隙.由于柔性滑块与滑道的接触状态和摩擦情况比较复杂,采用有限元方法建立了柔性滑块的力学模型,基于罚函数方法建立含Karnopp摩擦柔性滑移铰接触力模型,通过试算迭代法判断柔性滑块各节点的接触状态,基于KED方法和Newmark方法给出了含该滑移铰机械系统动力学方程的数值算法.最后,以含Karnopp摩擦的柔性滑移铰和驱动摆杆构成的机械系统为例进行动力学仿真,分析了其动力学特性,验证了本文给出的方法的有效性.     

深圳河湾水质数值模拟研究

基于EFDC模型和WASP模型建立了深圳河湾水动力和水质模型,采用2011年实测数据对模型进行率定和验证,结果表明,计算值与实测值吻合较好,丰枯季高低潮位平均误差小于0.20 m,DO、BOD5平均误差小于20%,TN、TP和Chl a(叶绿素a)平均误差小于30%。在此基础上进行案例研究,研究结果表明,氮、磷营养盐负荷削减80%对藻类生长的影响不明显;削减95%负荷时,Chl a浓度下降40%。     

To what end? Drip irrigation and the water–energy–food nexus in Morocco

This article draws on three case studies of drip irrigation adoption in Morocco to consider the water–energy–food nexus concept from a bottom-up perspective. Findings indicate that small farmers' adoption of drip irrigation is conditional, that water and energy efficiency does not necessarily reduce overall consumption, and that adoption of drip irrigation (and policies supporting it) can create winners and losers. The article concludes that, although the water–energy–food WEF nexus concept may offer useful insights, its use in policy formulation should be tempered with caution. Technical options that appear beneficial at the conceptual level can have unintended consequences in practice, and policies focused on issues of scarcity and efficiency may exacerbate other dimensions of poverty and inequality.     

辽宁省水利保障能力评价模型研究

为了研究辽宁省水利建设能否保障该省区域经济社会可持续和谐发展,以辽宁省第一次全国水利普查成果为依托,建立一套水利保障能力评价指标体系,利用模糊聚类综合评判模型和主客观赋权方法,对辽宁省各地市水利保障能力进行排序。评价结果表明,辽宁省各地市水利发展很不平衡,需要因地制宜,科学调整发展战略。     

流域水文模型在临界雨量分析中的应用研究

为提高无资料地区临界雨量分析结果的精确度,采用双曲正切产流模型和单位线流域汇流模型,结合山西省清凉寺沟流域水文下垫面产汇流模型参数,对实测暴雨洪水进行了模拟分析。结果表明:径流深及洪峰流量的合格率均为75%,参数是合理、可靠的,据此得出了该流域不同流量级时的临界雨量。