论压力容器的“断裂前渗漏”准则及其工作的可靠性

本文讨论了一些目前已提出的压力容器"断裂前渗漏"准则,认为对各向同性材料制成的容器,实现这一准则是困难的.提出可利用破坏评定图评定容器工作的可靠性,计算容器的工作安全系数或可靠度.     

Occupational noise exposure of fishermen aboard small and medium-scale fishing vessels

There is little information about occupational noise exposure of fishermen working on small and medium-scale fishing vessels, mainly because of the difficulty of conducting noise exposure surveillance in such occupations. The objective of the current study was to evaluate the exposure of this group of workers to occupational noise using a combined measurement and questionnaire approach. Sound pressure levels were measured aboard 24 fishing vessels at all working or resting locations and during speeding and slow-down moods of the engine. The average existence times of the crew at such locations were collected using a questionnaire. The average daily noise exposure levels (L_EP,d,8h) for engine mechanics in all vessel types (91.2–94.3 dBA) and the tiller operators in gill/trammel and purse seining vessels (84.7–88.4 dBA) exceeded the NIOSH recommended exposure limit of 85 dBA. Other crew members were found to be exposed, on average, to daily noise exposure levels slightly lower than the recommended one (81.6–83.5 dBA). However, direct personal dosimetry for five crew members revealed daily noise exposure levels 1.1–5.1 dBA higher than the calculated averages, which might be attributed, partly, to sources of uncertainty. The results of this study suggest that small and medium-scale vessels fishermen are at high risk of NIHL, calling for development and enforcement of suitable interventions for hearing protection of the workforce of this sector.     

Decentralised H ∞ filtering of interconnected discrete-time fuzzy systems with time delays

This article considers the decentralised H _∞ filtering of interconnected discrete-time fuzzy systems with time delays based on piecewise Lyapunov–Krasovskii functionals. The fuzzy system consists of J interconnected time-delay discrete-time Takagi–Sugeno fuzzy subsystems and the decentralised H _∞ filter is designed for each subsystem. It is shown that the stability with H _∞ performance of overall filtering error system can be established if a piecewise Lyapunov–Kroasovskii functional can be constructed, and moreover, the functional can be obtained by solving a set of linear matrix inequalities that are numerically feasible. A simulation example is given to show the effectiveness of the presented approach.     

Some properties of cyclic codes†

This paper will investigate the properties of cyclic codes under the transformation,$ It is discovered that for all the non-shortened cyclic codes (binary or (/-nary), if (g(x), (x?1)) =1 then the set of all the codewords is invariant under the transformation f_b. If (g(x), Lx?1)) = (x; ? 1), then the set of all the code words is generated by g(x)/(x ? 1). Next this paper shows a systematic method for the construction of orthogonal cyclic codes in which all the code vectors are orthogonal to each other even to itself     

On decentralised control of non-linear interconnected systems

The asymptotic stabilisation problem of a class of large-scale interconnected systems is considered, where the non-linear interconnections between subsystems satisfy quadratic constraints that are functions of the whole system's state vector. A decentralised combined observer-controller compensator is proposed and analysed, where the subsystems’ state vectors are estimated using local sliding mode observers. The closed-loop system driven by the proposed decentralised compensator is guaranteed to be asymptotically stable subject to two conditions that are easily verifiable. Simulation results illustrate the effectiveness of the proposed decentralised combined observer-controller compensator.     

商代青铜酒器文化研究

商朝是中国青铜时代的鼎盛时期,以青铜制作的器具众多,其中不乏大量的酒器,从酒器的造型与纹饰可以反应出商当时的一个社会文化背景,即商人好酒。     

Design, analysis and experimental validation of a robust nonlinear path following controller for marine surface vessels

The problem of path following for marine surface vessels using the rudder angle is addressed in this paper. A four-degree-of-freedom nonlinear surface vessel model, together with the Serret-Frenet equations, is introduced to describe the ship dynamics and path following error dynamics. While similar models have been used and reported in the literature for path following control algorithm development, the novelty of the approach presented in this work lies in the following aspects. (a) The back-stepping nonlinear controller design is based on feedback dominance, instead of feedback linearization and nonlinearity cancelation; (b) additional design parameters are employed in the Lyapunov function that lead to simplification of the controller in the design procedure and normalization of different variables in the Lyapunov function to improve the controller performance; (c) relying on feedback dominance and the introduction of the additional parameters in the Lyapunov function, the resulting controller is almost linear, with very benign nonlinearities allowing for analysis and evaluation; and (d) the performance of the nonlinear controller, in terms of path following, is analyzed for robustness in the presence of model uncertainties. The simulation results are presented to verify and illustrate the analytic development and the effectiveness of the resulting control against rudder saturation and rate limits, and delays in the control execution, as well as measurement noises. Furthermore, the control design is validated by experimental results conducted in a tank using a model ship.     

分散自校正鲁棒控制研究及其应用

本文研究了互联系统的分散自校正鲁棒控制;在互联项和参数扰动有限的情况下给出了自适应算法以及收敛性和系统的稳定性定理,将该控制方案在有水和电联系的两台水轮机调节中应用,仿真结果证实了该控制方案的有效性。     

基于EMD和模极大值的造影图像血管提取

针对冠脉造影图像噪音大且血管边缘模糊问题,提出一种基于经验模态分解的冠脉造影图像血管提取方法以较完整有效地提取出造影图像中的血管信息。该方法首先对图像预处理后的造影图像进行经验模态分解,将其分解成若干图像层,保留包含血管信息的图像层并丢弃含非血管信息图像层;其次对保留的图像层进行血管特征提取,依据连通区域的一系列属性来提取图像层中血管信息以获取清晰明显的血管段;最后通过层间信息相互参照,重构血管脉络明显的心血管图像。实验证明了方法有很高的精确度和实际的医用价值。     

分布式继电保护整定计算系统

基于对传统C/S模式的分析,提出一种适应互联电网快速发展的、全新的分布式继电保护整定计算系统,介绍了这种新体系需要考虑的问题、优缺点以及实现方法。