Authorship patterns in theory based versus research based journals

This article examines authorship pattern in two theory based journals, one American and one Canadian. Data were collected on the number of single, double, and multiple authors from 1955 to 1994 inEducational Theory and from 1970 to 1994 in theJournal of Educational Thought. The years were, in turn, divided into eight and five five-year intervals respectively. Frequencies and percentages were generated for each interval and chi-squares were computed between intervals and overall. In addition, author/article ratios were calculated for each year forEducational Theory. Results revealed that the majority of authorships were single in both journals regardless of the date of publication. These findings further challenge de Solla Price's predictions that co-and multiple authorships would eventually outnumber single authorships. The failure to distinguish between journal type and to allow for discrepancies within disciplines raises new concerns about conclusions drawn, to date, in the literature.     

Simulation of clusters formation in Al-Cu based and Al-Zn based alloys

A Monte Carlo computer simulation is adopted to investigate the role of micro-alloying elements Mg and Ag in Al-Cu and Al-Zn alloys. Small amount additions of Mg to the Al-Cu alloy markedly retard the formation of Cu clusters due to the preferential trapping of free-vacancies available for Cu diffusion. On the other hand, additions of Mg to the Al-Zn alloy promote the formation of Zn clusters due to the preferential Mg-Zn interaction. As for the effect of Ag, it is found that, in both Al-Cu-Mg and Al-Zn-Mg alloys, Ag atoms are preferentially bounded to Mg-Cu-vacancy or Mg-Zn-vacancy complexes. However, in Al-Cu-Mg alloy Ag atoms interact with Mg, while in Al-Zn-Mg alloy they interact with both Mg and Zn.     

基于有限元计算的磁流变液特性分析及其与基于磁偶极子模型结果的比较

采用ANSYS有限元软件,计算了磁流变液单链在剪切过程中的力学特性,并以此为基准分别与基于简化偶极子模型和基于不简化偶极子模型的结果进行了比较。结果表明,简化偶极子模型在描述磁流变液力学特性方面具有较高的精度,但由其得到的剪切屈服应力略低于有限元计算结果。这对于改进偶极子模型以建立磁流变液性能更精确快捷的多层次描述方法,进而设计高性能磁流变液具有重要的意义。     

基于网络标签的研究

通过对社区知识结构的研究分析，采用社区知识融合的方法来促进社区知识的演进。标签推荐事实上是元数据抽取的一种，用户在标注内容时有特定的习惯，这使得自动标注成为可能。社区知识融合的方法能够增强元数据的描述性、可查找性，辅助用户获得自己感兴趣的内容。     

Petri net based scheduling

Timed Petri nets can be used to model and analyse scheduling problems. To support the modelling of scheduling problems, we provide a method to map tasks, resources and constraints onto a timed Petri net. By mapping scheduling problems onto Petri nets, we are able to use standard Petri net theory. In this paper we will show that we can use Petri net based tools and techniques to find conflicting and redundant precedences, upper- and lower-bounds for the makespan, etc. This is illustrated by a Petri net based analysis of the notorious 10×10 problem due to Fisher & Thompson (1963)     

硅油基磁性液体

共沉淀法制备的磁性颗粒经分散剂处理后悬浮于硅油中得到了硅油基磁性液体。为了得到稳定的胶体，合成了一系列与硅油匹配很好的有机硅膦酸分散剂，其化学通式为XPS表面分析表明磁性颗粒与分散剂之间的作用为化学吸附。本文还测试了磁性液体的一些物理性能以及粘度随温度的变化情况。     

Probabilitically based decision support

Probabilistic Safety Assessment, usually referred to by the acronym PSA, has by now become a recognized tool for safety analysis of nuclear power plants. In recent years, an increasing number of plants have been analysed, and as the technique has matured, the area of application of PSA based analyses has been expanded. Thus, probabilistic methods are now used increasingly in the day-to-day work concerning the safety, maintenance and operation of plants. In this context, the question of interpretation and application of analysis results in various decision situations has become crucial. This paper gives some comments concerning the basis for decision making involving probabilistic analyses.     

Carbon nanotube based photocathodes

This paper describes a novel photocathode which is an array of vertically aligned multi-walled carbon nanotubes (MWCNTs), each MWCNT being associated with one p-i-n photodiode. Unlike conventional photocathodes, the functions of photon-electron conversion and subsequent electron emission are physically separated. Photon-electron conversion is achieved with p-i-n photodiodes and the electron emission occurs from the MWCNTs. The current modulation is highly efficient as it uses an optically controlled reconfiguration of the electric field at the MWCNT locations. Such devices are compatible with high frequency and very large bandwidth operation and could lead to their application in compact, light and efficient microwave amplifiers for satellite telecommunication. To demonstrate this new photocathode concept, we have fabricated the first carbon nanotube based photocathode using silicon p-i-n photodiodes and MWCNT bunches. Using a green laser, this photocathode delivers 0.5?mA with an internal quantum efficiency of 10% and an I(ON)/I(OFF) ratio of 30.     

基于知识工程复杂产品开发过程的模型研究

 为了提高复杂产品开发的效率,驾驭复杂产品开发过程各个环节相互关联的复杂性,提出一种基于知识工程的复杂产品开发过程新模型.该模型把知识工程理论融入复杂产品开发全生命周期过程中,通过知识推理技术从数据库和知识库中获取相应开发阶段的知识和数据来驱动和指导整个复杂产品开发过程,以更好地重用设计知识.研究了该模型的关键技术,包括复杂产品开发知识处理技术和基于知识的CAD/CAM/CAE/CAPP集成技术,提出了两种知识处理方法,即基于规则-对象-框架的知识处理方法和基于规则-实例的知识处理方法,并研究了相应的推理算法;以知识库、数据库、规则库和实例库为基础,通过PDM,STEP中型文件、规则、实例和知识等,实现CAD/CAM/CAE/CAPP集成.最后,通过数据库技术、编程语言VC# . NET和CATIA软件实现了隧道掘进机（TBM）主机的快速设计系统,有效地减少了隧道掘进机主机开发的复杂性和缩短开发周期,以TBM主机为应用实例进一步介绍该模型的合理性和有效性.     

Carbon based conductive photoresist

A conductive photoresist for photolithographic application was studied here. The negative near-UV sensitive epoxy-based photoresist was used as a polymer matrix and conductive carbon black was used as functional filler. DC electrical resistivity of composite as a function of filler concentration has a well-known S-shape. After UV-exposure the resistivity of the composite decreases for almost five orders of magnitude, mostly at percolation threshold (approx. 0.6 vol.%). This effect can be attributed to the fully cross-linked polymer structure formed during UV-exposure of the composite. The resistivity of prepared samples also depend on the state of dispersion of the functional filler obtained using different dispersing additives. Composites with better dispersed particles have lower resistivities. This effect remained below one order of magnitude and decreased after UV-exposure. The composites with carbon black concentration of up to 1.1 vol.% are suitable for spin-coating and photolithography.     

A simulation based continuous improvement approach for manufacturing based field repair service contracting

This paper develops and tests a novel extension to traditional supplier selection practice, with a particular focus on the concluding stages of a manufacturing-based field service. Action-based research was used to design and develop a discrete event simulation decision support for a large multinational manufacturing organisation with a significant after-sales service supply chain. The framework has been designed to identify and validate the value attributable to collaborative supplier contracting with built-in costed performance improvement targets. Use of the framework in the case organisation was found to produce greater cost savings over traditional practice, facilitating extended supply chain contracts. The results provide evidence of the high level of savings achievable while also improving customer delivery through targeted service improvements over the contracts life cycle. This framework advances beyond the prevalent practice of cost-focused short-term adversarial supply contracting and is innovative in terms of its continuous improvement simulation based framework design.     

Wear behaviour of organic asbestos based and bronze based powder metal brake linings

Bronze based brake linings, were produced by powder metallurgy technique and their wear behaviour was investigated and compared to that of asbestos ones. Bronze powders were compacted under 350, 500 and 600 MPa pressures and sintered at 810 °C in ammonia atmosphere for 75 min. For the same friction distance, it was determined that temperature increase in the bronze based brake linings was lower than that of asbestos based ones. However, higher wear rate was observed in the bronze based brake linings. Moreover, thermal conductivity was decreased with high porosity level with low densities. Although, friction coefficient remained the same during breaking, an increase in wear resistance was observed.     

石墨对Ni-Cr和Ni-Cr-W复合材料摩擦性能的影响

采用粉末冶金方法制备了Ni-Cr基自润滑复合材料,研究了Ni20Cr-石墨与Ni20Cr-10W-石墨复合材料中石墨含量和添加W后对材料力学性能和摩擦性能的影响.结果表明:随着石墨体积分数的增加,Ni20Cr-石墨复合材料的显微硬度和致密度不断降低;将石墨添加到Ni20Cr-10W复合材料中,材料摩擦系数明显降低,在每个试验温度下,复合材料的摩擦系数都随石墨含量的增加出现先增加后降低的变化规律;在Ni20Cr-石墨复合材料中添加体积分数10%的W后,复合材料显微硬度有所增加;当石墨体积分数为10%时,材料的摩擦系数在各个试验温度下均有所增加,当石墨体积分数为5%和15%时,复合材料的摩擦系数在整个温度范围内均有所降低;在整个温度范围内,Ni20Cr-10W-15石墨复合材料的摩擦系数最低.     

The connection between Bell's inequalities based on probabilities and those based on correlations

Abstract

Violation of Bell inequalities is widely regarded as a definitive test for non-locality. However, Bell correlational inequalities must always be satisfied by all jointly present, cross-correlated data. The correlations of variable pairs obtained in repeated runs are not cross-correlated in this way and are not required to satisfy the Bell inequality. In addition, by using information regarded as non-local, proper joint correlations may be computed among counterfactual and measured variables. These correlations satisfy the Bell inequality, but are spatially non-stationary in angle. By using a simple symmetry condition, such considerations may be extended to inequalities in probabilities. The latter may be derived directly from correlational inequalities developed by Clauser, Horne, Shimony and Holt (CHSH). Violation of either correlational or probabilistic Bell inequalities then implies that the Bell correlation cannot be accounted for by a stochastic process that is spatially stationary in angle coordinates. However, other processes may still be allowed.     

Some barium titanate based dielectrics

Some new potential dielectric materials have been made through the cross-substitution of Ba²⁺ by a 1:1 molar combinations of tri-(La³⁺) and mono-valent (Li⁺, Na⁺, K⁺) ions at the Ba²⁺ site in BaTiO₃. Chemical analysis shows that compositions in the potassium series are about 6·1% deficient in their K₂O content and exhibit interesting dielectric relaxations. The cross-substitution has lowered theT _c down to room temperature. The disorder in the larger ‘A’ cation sublattice of the three systems has been established by infra-red and x-ray data. This leads to microscopic compositional variations, which in turn can account for the diffuseness of the dielectric anomalies observed in the barium titanate-rich compositions (0⩽x⩽0·3). since deceased.     

Josephson Junction based Quantum Computing

Among the physical realizations of the elements required for quantum computation nano-scale electronic devices [2, 10, 12, 16] are very promising. They can be easily integrated into electronic circuits and scaled up to large numbers of qubits. Here we describe qubits based on low-capacitance Josephson junctions. In these systems Coulomb blockade effects allow the control of the charge on a superconducting island. They constitute quantum bits, with logical states differing by the charge on one island. Single- and two-bit operations can be performed by manipulating applied gate voltages. The phase coherence time is sufficiently long to allow a series of these steps. In addition to the manipulation of qubits, the resulting quantum state can be read out by coupling a single-electron transistor capacitively to the qubit. Received: October 23, 1998; revised version: September 21, 1999