NZ8合金在360℃锂水和400℃蒸汽中腐蚀后氧化膜的拉曼光谱分析(英文)

通过拉曼光谱法研究NZ8合金在360℃锂水和400℃蒸汽的静态高压釜中腐蚀后氧化膜的晶体结构。结果表明,NZ8合金的氧化膜主要由单斜氧化锆组成,其中包括少量畸变的四方氧化锆。随着腐蚀时间的延长,氧化膜中平均四方氧化锆含量不断减少,单斜氧化锆含量不断增加,四方氧化锆在向单斜氧化锆转变。从氧化膜/基体界面到氧化膜外表面,四方氧化锆含量不断减少,界面处四方氧化锆含量最高。NZ8合金在360℃锂水中腐蚀98d后所得氧化膜/金属界面处四方氧化锆含量较其在400℃蒸汽中腐蚀70d所得氧化膜/金属界面处四方氧化锆含量高,而且在400℃蒸汽中腐蚀后氧化膜外表面没有四方氧化锆形成。四方氧化锆向单斜氧化锆的转变决定了NZ8合金的耐腐蚀性能。氧化膜中四方氧化锆含量越高,则锆合金的耐腐蚀性能越好。     

钢水喷镁精炼及其对钢性能的影响

由于镁对钢的脱氧、脱硫、净化钢水及转变夹杂物形态的良好作用,近年来许多冶金工作者致力于加镁精炼钢水的研究工作,但因在冶金温度下镁的蒸汽压很高,而其在钢水的溶解度又极小,加入困难,这方面的研究多归于失败。本文利用阿亨大学热力学数据库计算了以氩作为载气喷镁的脱氧、脱硫作用,以及压力和氩量对其影响,通过实验制定了行之有效的喷吹工艺,选择了合适的控制参数。
在1-3大压下,氩量为0.1-0.3N.L/m:n,可以向钢水成功地喷入镁。经过镁精炼的钢水,氧含量可降至4ppm,硫含量降至10ppm,氧化物及硫化物的评级均为0级,其尺寸均在5μm之下。随着喷镁量的增加(钢水重量的0.062至%0.56%),夹杂物中镁的氧化物及硫化物量增加,夹杂物总量减少且呈球形,此种夹杂物在热形变中不变形。因此在通常材料中所存在的各向异性完全消失,特别是缺口冲击韧性横向性能值提高了2~3倍。文章对材料在不同温度下的冲击韧性、过渡温度及断口夹杂物的形态进行了研究和论述。     

Interface control for resolved CFD-DEM with capillary interactions

In this work, a resolved CFD–DEM coupling model for the simulation of gas-liquid-solid flows is developed: the interface capturing method based on the colour function is employed for fluids (i.e. a gas and liquid) whilst Discrete Element Method (DEM) is used for particles. The Volume Penalisation (VP) method is adopted to consider the hydrodynamic interactions between fluids and particles along with the Immersed Free Surface (IFS) method, which artificially extends the gas-liquid interface into the interior of the particle to account for the wettability. The unique point of the proposed model is that the thickness of the gas-liquid interface can be controlled by using both interface compression and diffuse interface techniques simultaneously. From the simulation results, it is presented that the accurate evaluation of the surface tension force as well as the capillary force can be achieved by appropriately controlling the interface thickness. Moreover, the major two methods in the literature to calculate the capillary force are compared in this work. The validity of the proposed model is presented for both static and dynamic cases. The behaviour of two colliding particles with a dynamic liquid bridge is then simulated to demonstrate the applicability of the proposed model to a complex three-phase system.     

The use of personal protective measures in control of malaria in a defined community

Malaria is one of the main health problems in the non-immune immigrant workers and army personnel of the malaria endemic areas in Myanmar. Due to changes in the vector bionomics and multiresistant strains of P. falciparum, chemoprophylaxis alone is not an effective means of control of malaria in them. So it is envisaged that the combined used of personal protective measures (deltamethrin impregnated bed-nets, scalves and hand-bands) and the chemoprophylaxis will be an effective means of control of malaria in the define group of people. The study also intended to find out the side effects of the deltamethrin and feasibility and acceptability of methods by the users. The study was conducted in Theini Township, Northern Shan State, from March to November 1993. The study population consisted of all ages of both sexes 554 and 440 persons in the test and control groups respectively. At the initial phase of the study, malaria infected persons from both the groups were treated. The experimental group received personal protective measures with impregnation of bed-nets using 25 mg ai/m2 of deltamethrin at 4 monthly intervals and the scarves and hand-bands at twice the concentration of the insecticides at monthly intervals. Chemoprophylaxis was given to both the groups at weekly intervals using age adjusted dosage of Pyrixine tablet (sulfadoxine-pyrimethamine). The parasitological, entomological, and epidemiological indices were collected at two month intervals in both the groups. The study clearly showed the impact of personal protective measures and chemoprophylaxis on malaria infection in the studied subjects. During the study period, the out patient malaria cases of the test group was 6% to 11.2% and that of the control group was 12% to 21.6% in Theini Hospital. The reinfection rate of the test group (0.9 to 4.7%) was also significantly lower than the control group (6.1 to 14.3%) from July to November. Acceptance of the treated bed-nets, scarves and hand-bands was high and good compliance was found in the follow up. The results of the study clearly showed that malaria can be controlled effectively in the defined group of persons for a malaria transmission season by using chemoprophylaxis and personal protective measures.     

Electrical and photo-luminescence properties of ZnSe epitaxial layers grown on GaAs (100) by atmospheric pressure MOVPE: The role of substrate temperature

Epitaxial layers of ZnSe ranging in thickness from 5μm to 30 μm have been grown on GaAs (100) substrates over the temperature range 240° C to 340° C by atmospheric pressure MOVPE employing dimethylzinc and hydrogen selenide. An optimum growth temperature of 280 ± 5° C has been identified and when grown at this temperature the ZnSe epitaxial layers exhibit low resistivity (ρ_{298 K} ≤ 10 ohm · cm), a low compensation ratio (θ_{298 K} = 0.27), a carrier mobility (μ_{298 K}) of 250 ±10 cm²V^-1s^-1) and aren-type (n _{298 K} = 8.0 × 10¹⁴ cm^-3). The ratio of photoluminescence intensity measured at 298K and at 12 K is high (10⁴) and is dominated by a sharp emission due to excitons bound to neutral donors at 2.7956 eV. Mass spectrometric investigations of the chemical reactions occurring inside the reactor in the presence of the GaAs substrate indicate significant surface-controlled reactivity in the region of 280° C.     

A typology of human computation games: an analysis and a review of current games

Human computation games (HCGs) utilise human intelligence for the purpose of problem solving through games. Recently, HCGs have increased in popularity within various application areas. A proper system of describing such games is necessary in order to obtain a better understanding of the current body of work and identify new opportunities for future research directions. To date, however, there is little research conducted in understanding how such games could be classified in a systematic manner. Past classification schemes rely either on quality or entertainment aspects of these games. In order to have a deeper understanding of such games, this study argues that they should be classified via different dimensions. As a starting point, this paper reviews existing literature on HCGs and then develops a typology consisting of 12 dimensions and related strategies. This typology provides a holistic view of HCGs, and provides a common understanding of the domain among researchers and designers. The typology will help researchers to better understand the nature and consequences of HCGs, and designers better identify strengths and weaknesses of different strategies for each dimension, thus facilitating the creation of entertaining and effective HCGs.     

On-chip Fabry-Pérot interferometric sensors for micro-gas chromatography detection

We fabricated and characterized on-chip Fabry-Pérot (FP) vapor sensors for the development of on-column micro-gas chromatography (μGC) detectors. The FP sensors were made by coating a thin layer of polymer on a silicon wafer. The air-polymer and polymer-silicon interfaces form an FP cavity, whose resonance wavelengths change in response to the vapor absorption/desorption, thus allowing for rapid detection and quantification of vapors. For proof-of-concept, two polymers (PDMS and SU-8) were used independently and placed in an array in a microfluidic channel, and showed different sensitivities for different vapors. A sub-nano-gram detection limit and sub-second response time were achieved, representing orders of magnitude improvement over those previously reported. This on-chip design will enable the unprecedented integration of optical vapor sensors with μGC systems.     

Intermediaries: bridges across the digital divide

The challenge of bringing developing countries into the “information society” has been traditionally framed as bridging the digital divide. Meeting this challenge has predominantly been through technical solutions aimed at providing physical access to the Internet. Yet, other aspects of the divide such as low literacy rates, gender and religious issues arguably pose bigger hurdles in getting the benefits of the Internet to the vast majority of the population of developing countries. They are seldom aware of the information available on the net and even when they are, they have difficulty using it. To facilitate access and use of the Internet by the population, an intermediary is often needed. While case studies in the literature have shown several examples of such intermediaries, the role of this entity has not been conceptually examined. In this paper, we attempt to meet this knowledge gap by conceptualizing the characteristics, types and roles of the Intermediary entity. We present a view from practice through three vignettes of intermediaries from our own studies to illustrate our conceptualizations. Based on this, we discuss some implications for practice and offer directions for research.     

Effect of metal oxides on the microstructure of zinc ceramic

The effect of crystallization of ZnO on volt-ampere characteristics was investigated. It was shown that incorporation of Bi₂O₃, TiO₂, and SnO₂ causes crystal growth, while Sb₂O₅, CoO, and MnO slow crystal growth. The formation of a finely crystalline structure with thin layers of glass phase increases the volt-ampere characteristics. __________ Translated from Steklo i Keramika, No. 1, pp. 29–31, January, 2007.