流量测量新技术——非接触测量

介绍了我国石油部门现用(接触式)流量计的不足及非接触测量技术的优势;介绍了管外夹装式超声波流量计的基本原理、类型及其最新进展;提出了我国石油部门采用管外夹装式超声波流量计应注意选型、选点及操作、维修人员的培训问题。     

A new blind source separation method based on fractional lower‐order statistics

We proposed neural network structures related to multilayer feed‐forward networks for performing blind source separation (BSS) based on fractional lower‐order statistics. As alpha stable distribution process has no its second‐ or higher‐order statistics, we modified conventional BSS algorithms so that their capabilities are greatly improved under both Gaussian and lower‐order alpha stable distribution noise environments. We analysed the performances of the new algorithm, including the stability and convergence performance. The analysis is based on the assumption that the additive noise can be modelled as alpha stable process. The simulation experiments and analysis show that the proposed class of networks and algorithms is more robust than second‐order‐statistics‐based algorithm. Copyright © 2006 John Wiley & Sons, Ltd.     

超细粉FeCl3-插层石墨化合物的制备与表征

采用定量混合法,以鳞片石墨为主体材料制备了FeCl3-GIC,应用XRD技术表征其层间结构,结果证实所得产物的阶结构以3阶为主、混阶共存,3阶FeCl3-GIC的特征层间距为0.945 nm.应用振动样品磁强计测试产品的磁性能,结合EDS能谱图分析载流子的浓度变化,建立电荷迁移模型,讨论了石墨插层化合物的导电机理,应用红外热成像仪检测了粉末的干扰效果.研究表明超细粉FeCl3-GIC在军用远红外波段具有显著的消光特性.     

Report of the treasurer: 1989: The 1980s: A roller coaster decade for APA finances.

This report of the Treasurer provides information on the American Psychological Association's (APA) financial operations for the 1980s. From a financial perspective, the 1980s was unquestionably the most turbulent in the history of the APA. This report focuses on the revenues and expenses of the APA throughout the 1980s while giving a summary and conclusion of all the finances at the end of the report. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Negative differential perpendicular velocity in GaAs/AlAs superlattices

We investigate the doping level, hydrostatic pressure, temperature and superlattice parameter dependence of the perpendicular negative differential velocity (NDV) of GaAs/AlAs superlattices. The results show that NDV is a single Γ miniband effect. A qualitative agreement is found with Esaki's negative effective mass model, although a few limitations of this model are pointed out and some improvement is suggested.     

A quantitative assessment of LCOs for operations using system dynamics

Limiting conditions for operations (LCOs) define the allowed outage times (AOTs) and the actions to be taken if the repair cannot be completed within the AOT. Typically plant shutdown is required. In situations where the risk associated with the action, i.e. the risk of plant shutdown given a failure of the safety system, may be substantial, a strategy is needed to control the plant risk. In this study the changing operation modes are evaluated quantitatively and dynamically using the tool of system dynamics. System dynamics has been developed to analyze the dynamic reliability of a complicated system. System dynamics using the Vensim software have been applied to LCOs assessment for an example system, the auxiliary feed water system of a reference nuclear power plant. Analysis results of both full power operation and shutdown operation have been compared for a measure of core damage frequency. The increase in core damage frequency is used as a measure in this study. A time dependent framework developed in this study has been shown to be very flexible in that it can be applied to assess LCOs quantitatively under any operational context of the Technical Specifications in Final Safety Analysis Report of the reference plant.     

A note on ‘optimization of multi-pass turning operations using ant colony system’

An article by Vijayakumar et al. [Optimization of multi-pass turning operations using ant colony system, International Journal of Machine Tools and Manufacture 43(15) (2003) 1633–1639] proposed an ant colony optimization methodology for determining the machining parameters in a multi-pass turning operation model. By using the problem of Chen and Tsai [A simulated annealing approach for optimization of multi-pass turning operations, International Journal of Production Research 34(10) (1996) 2803–2825], they concluded that their ant colony approach outperformed the other optimization techniques proposed by other researchers. This note discusses an illustrative multi-pass turning problem, which was used in several literatures and demonstrates that the optimal solution as found by Vijayakumar et al. [1] is not valid.     

The revisit of QoS routing based on non‐linear Lagrange relaxation

The development of efficient quality of service (QoS) routing algorithms in a high‐speed networking or the next generation IP networking environment is a very important and at the same time very difficult task due to the need to provide divergent services with multiple QoS requirements. Recently, a heuristic algorithm H_MCOP, which is based on a non‐linear Lagrange relaxation (NLR) technique, has been proposed to resolve the contradiction between the time complexity and the quality of solution. Even though H_MCOP has demonstrated outstanding capability of finding feasible solutions to the multi‐path constrained (MCP) problem, it has not exploited the full capability that an NLR‐based technique could offer. In this paper, we propose a new NLR‐based heuristic called NLR_MCP, in which the search process is interpreted from a probability's perspective. Simulation results indicate that NLR_MCP can achieve a higher probability of finding feasible solutions than H_MCOP. We also verify that the performance improvement of a MCP heuristic has a tremendous impact on the performance of a higher level heuristic that uses a MCP heuristic as the basic step. Copyright © 2006 John Wiley & Sons, Ltd.     

c‐Type method of unified CAMG and FEA. Part 1: Beam and arch mega‐elements—3D linear and 2D non‐linear

Computer‐aided mesh generation (CAMG) dictated solely by the minimal key set of requirements of geometry, material, loading and support condition can produce ‘mega‐sized’, arbitrary‐shaped distorted elements. However, this may result in substantial cost saving and reduced bookkeeping for the subsequent finite element analysis (FEA) and reduced engineering manpower requirement for final quality assurance. A method, denoted as c‐type, has been proposed by constructively defining a finite element space whereby the above hurdles may be overcome with a minimal number of hyper‐sized elements. Bezier (and de Boor) control vectors are used as the generalized displacements and the Bernstein polynomials (and B‐splines) as the elemental basis functions. A concomitant idea of coerced parametry and inter‐element continuity on demand unifies modelling and finite element method. The c‐type method may introduce additional control, namely, an inter‐element continuity condition to the existing h‐type and p‐type methods. Adaptation of the c‐type method to existing commercial and general‐purpose computer programs based on a conventional displacement‐based finite element method is straightforward. The c‐type method with associated subdivision technique can be easily made into a hierarchic adaptive computer method with a suitable a posteriori error analysis. In this context, a summary of a geometrically exact non‐linear formulation for the two‐dimensional curved beams/arches is presented. Several beam problems ranging from truly three‐dimensional tortuous linear curved beams to geometrically extremely non‐linear two‐dimensional arches are solved to establish numerical efficiency of the method. Incremental Lagrangian curvilinear formulation may be extended to overcome rotational singularity in 3D geometric non‐linearity and to treat general material non‐linearity. Copyright © 2003 John Wiley & Sons, Ltd.     

打砖机动态压力测试仪的研制

打砖机动态压力测试仪是以单片机为核心的数字压力表。它能测出瞬时的最大压力并用数字显示出来，且具有读数准确、抗干扰能力强、测量精度高等优点．