A methodology for designing proof rules for fair parallel programs

We propose a methodology for designing sound and complete proof systems for proving progress properties of parallel programs under various fairness assumptions. Our methodology begins with a branching time temporal logic formula (CTL^*) formula that expresses progress under a fairness assumption. The next step obtains an equivalent fixpoint characterization of this CTL^* formula in theh2573u61256p3544/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-calculus. The final step uses the fixpoint characterizations to extract proof systems for proving progress under the fairness constraint. The methodology guarantees that the proof rules so obtained are sound and relatively complete in the sense of Cook.     

基于三维激光扫描的倾斜圆面直径测量系统

针对倾斜圆面的空间几何特征,提出将三维激光扫描技术与虚拟环境 引导定位结合的快速圆面直径测量系统。该系 统通过圆面边缘端点来约束移动激光扫描仪的扫描视角与深度,并在虚拟环境下实时跟随扫 描仪轨迹构建虚拟测量基准面, 进而参考已标识的端点与基准面相对位移变化,来逐步规划扫描仪的轴向运动路径,以此实 现边缘轮廓的自动高质量采样; 依据高度特征变化识别定位圆面边缘端点,并结合空间投影和最小二乘原理拟合出圆面直径 。为验证系统的精度和可靠性, 对处于不同倾斜状态的圆台工件(55±5mm)进行直径检测。结果显 示,系统可在3s内完成直径测量,检测分辨率为5μm、 检测精度为20μm。实际运行结果表明,该设计系统具有高自动性和 高效性,能很好满足在线生产中对倾斜圆面直径的检测要求。     

面向巡防系统的混沌视频加密技术研究

巡防系统具有远程视频图像传输的功能,考虑到视频信息传输过程中存在被恶意盗取造成信息严重缺失的情况,在视频传输前需对视频做加密处理。结合H.264视频压缩编码,采用Logistic混沌序列在CAVLC熵编码阶段对视频进行选择性加密,实现了加密与视频压缩编码兼容。并在Visual Studio 2013中完成了基于Logistic混沌视频加密的仿真,在MATLAB中通过计算视频图像加密前后的PSNR、SSIM及RGB直方图,分析了Logistic混沌视频加密性能。     

Monitoring and kinetic study of ammonia oxidation using dissolved oxygen electrode and NAD(P) H fluorometer

The ammonia oxidation of a mixed culture enriched from a wastewater treatment plant sludge was monitored by a DO probe and a nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) fluorometer. Under fixed aeration, DO reflected ammonia oxidation effectively. According to the DO profiles and the total ammonia concentrations analyzed experimentally, the ammonia oxidation kinetics of the enriched culture was determined. The ammonia oxidation rate was found sensitive to pH, especially at low total ammonia concentrations. At high concentrations of total ammonia, the maximum ammonia oxidation rate occurred at pH 7.6+/-0.1. At low concentrations, the pH sensitivity intensified significantly and the apparent optimal pH shifted higher with decreasing total ammonia concentrations, because NH3 molecules were the true substrate for ammonia oxidation and more NH4+ ions were converted to NH3 molecules at higher pH. The ammonia oxidation kinetics was therefore developed according to the concentration of NH3 molecules, instead of the commonly used total ammonia concentration. The kinetics followed Michaelis-Menten behavior for both DO and NH3 concentration: the maximum rate was 16.7+/-0.7 mg NH3-N/(g TSS-h) and the Michaelis constants for DO and NH3 were (14+/-2)% air saturation and (4.4+/-0.4) x 10(-2) (mg NH3-N/L), respectively. It was also concluded from the study that with or without exogenous organic substances, the NAD(P)H fluorescence of the enriched nitrifying culture was undetectable. The fluorescence did not respond to addition or depletion of substrate (ammonia, glucose, or acetate), change between aerobic and anaerobic conditions, or even KCN addition to kill the culture.     

某复杂高层商住楼结构设计

对某复杂高层商住楼进行了详细介绍,包括设计思想、设计要点与结构分析。重点讨论复杂高层计算模型的处理;解决了结构转换、短肢剪力墙布置等结构问题;对比分析SATWE和TAT两种程序计算结果。对类似工程具有一定的参考价值。     

An analytical approach to reveal the addition of heat-denatured whey proteins in lab-scale cheese making

A simple analytical procedure for the detection of self-aggregated heat-denatured whey proteins (HDWP) in model cheeses was developed. The principle of the approach lies in the solubilization of the cheese matrix by a sodium citrate solution (0.2 M, pH 7.0) resulting in the dissociation of the casein micelles and the insolubilization of HDWP aggregates, which are collected in the pellet after a centrifugation step. The reliability of the procedure was tested in lab-scale cheeses from peroxidase-positive pasteurized milk with different protein-based ingredients (microparticulated whey protein concentrate, milk protein concentrate, whey protein isolate and Ricotta cheese) at concentrations ranging from 0.2 to 1.2% protein (w/v on cheese milk). A linear relationship between the amount of the HDWP added to cheese milk and that recovered from model cheeses was observed. Heat-damage indicators, furosine and lysinoalanine, showed levels in the experimental cheese samples not related with added HDWP, but represented a source of information on the ingredients other than liquid milk. Overall, in the model cheeses, the proposed method was an easy-to-apply and reliable tool for the evaluation of the presence of HDWP-based products. Further investigation is required for the application to real cheeses and for the evaluation of possible interferences from proteolysis during ripening.     

Non‐Lithographic Fabrication of All‐2D α‐MoTe2 Dual Gate Transistors

As one of the emerging new transition‐metal dichalcogenides materials, molybdenum ditelluride (α‐MoTe₂) is attracting much attention due to its optical and electrical properties. This study fabricates all‐2D MoTe₂‐based field effect transistors (FETs) on glass, using thin hexagonal boron nitride and thin graphene in consideration of good dielectric/channel interface and source/drain contacts, respectively. Distinguished from previous works, in this study, all 2D FETs with α‐MoTe₂ nanoflakes are dual‐gated for driving higher current. Moreover, for the present 2D dual gate FET fabrications on glass, all thermal annealing and lithography processes are intentionally exempted for fully non‐lithographic method using only van der Waal's forces. The dual‐gate MoTe₂ FET displays quite a high hole and electron mobility over ≈20 cm² V^?1 s^?1 along with ON/OFF ratio of ≈10⁵ in maximum as an ambipolar FET and also demonstrates high drain current of a few tens‐to‐hundred μA at a low operation voltage. It appears promising enough to drive organic light emitting diode pixels and NOR logic functions on glass.     

ARE法沉积的立方氮化硼薄膜生长过程的研究

采用逆序法研究了通过活性反应离子镀技术沉积在单晶硅 (10 0 )上的c BN膜生长过程。在X射线光电子能谱分析仪上 ,用氩离子剥离c BN膜并进行膜的成分的深度分布及不同刻蚀深度处膜的价态分析 ,用富立叶变换红外透射谱分析不同刻蚀深度处的膜的相结构。结果表明 :在此生长条件下 ,c BN不能在基底上直接成核 ,而是先在基底上形成一层h BN ,然后c BN在其上生长。对这种生长顺序 ,引用c BN膜形成机制的压应力模型给予了解释     

Enrichment and coupling of the finite element and meshless methods

A mixed hierarchical approximation based on finite elements and meshless methods is presented. Two cases are considered. The first one couples regions where finite elements or meshless methods are used to interpolate: continuity and consistency is preserved. The second one enriches a finite element mesh with particles. Thus, there is no need to remesh in adaptive refinement processes. In both cases the same formulation is used, convergence is studied and examples are shown. Copyright © 2000 John Wiley & Sons, Ltd.