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1.
Thermal history and solute precipitation behavior of suspended solution droplets of sodium chloride (NaCl), magnesium sulphate (MgSO4), and zirconium hydroxychloride (ZrO(OH)Cl) evaporating at atmospheric and reduced pressures are studied. Experimental measurements on the variation of droplet diameter, solution concentration, and temperature during the evaporation period are presented and discussed. The results of solute precipitation behavior in solution droplets observed under an optical microscope are displayed and discussed. Results indicate that reducing the pressure (∼ 33 kPa) results in a change in the solution droplet evaporation rate, but the thermal histories of a particular solution droplet are similar at the atmospheric and reduced pressures. At atmospheric and reduced pressures used in this study, the d2 law for solution droplets is valid at early stages of the evaporation and before the solute precipitation initiates. Drying of MgSO4 and ZrO(OH)Cl solution droplets results in the formation of spherical particles, whereas drying of spherical NaCl solution droplets results in the formation of cubic particles.  相似文献   
2.
This paper discusses the seafloor thermalwater spout sedimentary activity in South Yongmei Depression according to the following evidences: the Yongmei region was in an extended tectonic environment of metaplateform and locally developed intracontinental rift aulacogen in company with the activity of rich alkali, high potassium volcanics of double-peak type. Several kinds of hydrothermal sedimentary rocks and the ore-bearing sedimentary formations of copper-polymetals, iron and manganese exist in this region with a zoning feature of the seafloor thermalwater spout sedimentation. Project supported by the Science Foundation of NECC for Returns Synopsis of the first author Wu Chengjian, associated professor, born in 1957, majoring in ore deposit and mineralgraphy.  相似文献   
3.
A new optimization model is discussed for the design of cellular manufacturing systems. It is based on an integer programming formulation that updates some other models by eliminating redundant machine assignment and cost coefficients dependent on cell configuration. To reduce computational burdens, a simplified integer programming model and a decomposition algorithm are proposed. Several computer solutions were performed to evaluate the performance of the new model. The computational results are discussed.  相似文献   
4.
In an attempt to develop new catalysts for the formation of formaldehyde from methane, the promotion effect of Fe on SiO2 and that of Sn on WO3 have been studied. The formation of formaldehyde on silica can be appreciably enhanced by the impregnation of Fe, as far as iron loadings are kept below 0.1 atom.% (Fe/Si × 100). In the case of Sn---W---Ox catalysts, both the addition of Sn to WO3, and that of W on SnO2 were effective to the selective formaldehyde formation. Absorption spectra (UV-Vis) and ESR measurements revealed that tetrahedrally coordinated Fe3+ in the silica network plays an important role in the formation of formaldehyde. A thin surface layer consisting of W and Sn oxides can account for the selective formaldehyde formation on the Sn---W---Ox catalysts.  相似文献   
5.
A complete mathematicalhumerical model is proposed, in order to simulate the performance characteristics of a novel concept of a drying heat pump based on the theory of minimum energy cyclcs. The drying heat pump involvcs vapour condensation in a Lava1 nozzle. removal of the liquid phase in a supersonic separator as well as compression of the working medium. which is superheared vapour.  相似文献   
6.
Banding formation and eutectic lamellar growth in a directionally solidified Ni50Al20Fe30 alloy were investigated. It was found that the banding area consists of two layers. The first layer is a γ layer, while the subsequent one is a γ layer. The composition of various phases around the banding area changes with the solidification process. The banding is formed by two steps process and caused by factors such as the fractions during the sample growth process. It was found that the band was found at relatively low growth rate. Therefore. this study indicates that increasing the growth rate is an effective method to eliminate the band formation. Eutectic lamellae nucleate and grow again after the banding formation. During the initial transition lamellar growth, the relationship between the square lamellar spacing, γ2, and the distance from, the banding, d, can be described by the following equation: γ2 = K [1-exp(A.d)] where K and A are constant.  相似文献   
7.
This paper presents a novel distributed control scheme of multiple robotic vehicles. Each robotic vehicle in this scheme has its own coordinate system, and it senses its relative position and orientation to others, in order to make group formations. Although there exists no supervisor and each robotic vehicle has only relative position feedback from the others in the local area around itself, all the robotic vehicles are stabilized, which we have succeeded in proving mathematically only in the cases where the attractions between the robots are symmetrical. Each robotic vehicle especially has a two-dimensional control input referred to as a “formation vector” and the formation is controllable by the vectors. The validity of this scheme is supported by computer simulations.  相似文献   
8.
9.
本文采用气体蒸发法制备出粒度不到5nm的Sn及其氧化物的超微粉。利用热重,差热分析和X射线衍射谱等测试方法研究了热处理制度对其粒度,成份和气敏特性的影响,发现了SnO_2正交相的存在。  相似文献   
10.
In the micro drilling of precision miniature holes, the formation of exit burrs is a topic of interest, especially for ductile materials. Because such burrs are difficult to remove, it is important to be able to predict various burr types and to employ burr minimisation schemes that consider burrs’ micro-scale characteristics. In the present work, an artificial neural network (ANN) was used to predict the formation of burrs in the micro drilling of copper and brass, along with burr formation/optimisation analysis specialised for micro drills. The influence of cutting conditions, including cutting speed, feed and drill diameter, upon exit micro burr characteristics such as burr size and type was observed, analysed and classified. Based on the results, an empirical equation to predict micro burr height is proposed herein. The classification results were compared with conventional burr cases using burr control charts. Then, micro burr types were predicted by means of an ANN, using the influential parameters as input vectors. The usefulness of the proposed scheme was demonstrated by comparing the experimental and prediction/analysis results.  相似文献   
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