Free radical solution oligomerization of styrene in a continuous-stirred tank reactor train

For free radical oligomerization of styrene, a scheme for calculating the molecular weight distribution and conversion in a continuous-stirred tank reactor (CSTR) train is developed, which also allows the calculation of molecular weight distribution (MWD) for batch reaction. Calculations show that under conventional or near dead-end condition: (1) increasing initial initiator concentration, reaction time and reaction temperature, and decreasing initial monomer concentration cause P?_n and P?_w to decrease and MWD to narrow; (2) increasing initial initiator concentration, reaction time and reaction temperature, and increasing monomer concentration cause monomer conversion to increase; (3) a single CSTR gives a lower rate of oligomer production, but a narrower MWD than does a batch reactor.     

应力作用下的相变

水静压抑制Fe-C和钢中体积膨胀型相变，如铁素体、珠光体、贝氏体和马氏体相变。单向应力促发铁素体和珠光体相变，拉应力的效果尤为显著。0．38C-Cr-Mo钢中，铁素体、珠光体和贝氏体相变在应力下的动力学，可由Johnson-Mehl-Avrami方程中加入应力因子经修正来描述。由于铁素体和珠光体的化学驱动力小，应力所作膨胀功使形核率(J^*)增高和孕育期τ缩短。而贝氏体相变中，可能由于应力下碳自奥氏体贫化，或减少相界面能，从而使τ增高和τ缩短，待试验予以证明。水静压对Ms温度影响的定量描述因不同材料而异。列出Patel-Cohen所建立的dMs／dσ方程，及本文作者提出的应力影响Ms的方程。应力诱发马氏体会改变其晶体学及形态，提出以形核率的数值来判定其形态。奥氏体的力学稳定化在马氏体相变中主要由于奥氏体强化所导致，在贝氏体相变中却主要由于晶体学阻碍长大所造成的。     

Coalescence of tungsten grains around molybdenum grains in the presence of a liquid phase

The microstructural evolution of W–22.4Mo–7.8Ni–3.4Fe was investigated in this study. A first liquid phase primarily composed of Ni, Fe, and Mo resulted in the coexistence of large W–Mo grains having Mo-rich cores and small W grains.     

马氏体相变研究的进展和瞻望SCIEI

叙述马氏体相变研究的一些进展和瞻望,包括马氏体相变的定义,马氏体相变热力学,奥氏体状态对马氏体相变的影响,动力学,形核和长大,以及马氏体相变晶体学。     

Studies on electric-discharge machining of non-contact seal face grooves

In this paper, the electric-discharge machining (EDM) of non-contact seal grooves was studied. Two types of material, namely: tungsten carbide and silicon carbide were tested by EDM due to their hard machining behaviors. The geometry of seal grooves is another reason why grinding or other precision machining processes cannot be applied. Four parameters of EDM processes were studied, namely: electrode material, pulse duration, discharge current, and polarity. According to experimental results, the optimal process parameters were obtained based on the specimen’s qualities, such as surface roughness and depth of cut. An industrial example was also studied in the final stage of the proposed paper.     

Oxidation of Si-based ceramics in the presence of alkali halide vapors

Nonoxide silicon-based ceramics owe their oxidation resistance to the formation of a thin silica film that separates the ceramic from oxidizing environments. This silica film can be fluxed by alkali oxides to form low-melting alkali silicate corrosion products that do not provide protection. Alkali chlorides and other halides have sufficiently high vapor pressures that silica fluxing can occur without the formation of a condensed halide salt. The rates of oxidation of Si, SiC, and Si₃N₄ are influenced by the composition of gas mixtures containing these species.     

Determination of Active Slip/Twinning Modes in AZ31 Mg Alloy Near Room Temperature

In order to determine the deformation modes in AZ31 magnesium alloy at room temperature, computer simulations of deformation texture development and calculation of formability have been carried out. The simulation results were compared with the measured texture results. Based on agreement between the experiments and simulations the active deformation modes were determined. A Visco Plastic Self Consistent model was employed for the simulation of plastic deformation. Simulations and experiments were performed for different initial textures. The goal of the study was to develop the understanding of deformation texture evolution and its effects on mechanical properties of magnesium, with an ultimate goal of improving room temperature formability of magnesium alloys. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati, OH, October 15-19, 2006.     

A legitimacy challenge of a cross-cultural interorganizational information system

This paper studies the adoption and diffusion of a cross-cultural Interorganizational Information System (IOS), which is used to streamline the processing of financial transactions between European investment fund companies and Taiwanese banks. Drawing from institutional and organizational legitimacy theory, we argue that the adoption and implementation of technological innovation is contingent upon its alignment with three institutional pillars in different countries and the deployment of legitimation strategies by stakeholders. Departing from classical innovation diffusion theory, our empirical investigation reveals that the implementation of a cross-cultural IOS is a dynamic process involving the recognition, understanding, and management of the regulative, normative, and cognitive challenges arising in two different institutional settings. This paper contributes to the growing body of research that highlights the significance of social and institutional influences on the adoption of IOS in a global environment.     

From Job Characteristics to Job Satisfaction of Foreign Workers in Taiwan's Construction Industry: The Mediating Role of Organizational Commitment

The purpose of this study was to investigate the relationships among job characteristics, organizational commitment, and job satisfaction of foreign workers in Taiwan. Overall, 440 Thailand foreign workers were recruited and structural equation modeling was used to test the research hypotheses. The results of this study supported all proposed hypotheses. Job characteristics had a positive effect on job satisfaction of foreign workers. However, the results showed an indirect effect of job characteristics on job satisfaction via organizational commitment. Moreover, the findings suggested that job autonomy is better compared to other job characteristics. This study contributes to the existing literature by stressing the importance of such relationships in the cross‐cultural management enterprises, particularly those concerning foreign workers.     

Task rescheduling optimization to minimize network resource consumption

An increasing number of big-data services are being deployed in a cloud computing environment, attracted by the on-demand service, rapid elasticity, and low maintenance costs. As a result, ensuring the quality of service has become an important research problem. Traditionally, task rescheduling is used to ensure a consistent quality of service in the event of failure of a virtual machine. However, the network resource consumption of different rescheduling methods varies. To address this problem, we propose a task rescheduling method that minimizes network resource consumption.The method includes three algorithms. The first obtains a set of good virtual machines from the large quantity of service-providing virtual machines using the skyline operation. A ranking algorithm then fuses the data size and the task emergency to identify significant tasks. Finally, we present an algorithm that automatically determines the optimal insertion point for each task. To verify the effectiveness of the proposed method, we extend the renowned simulator CloudSim and conduct a series of experiments. The results show that our method is more efficient than other methods in terms of network resource consumption.