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81.
C.P. Paul P. Ganesh S.K. Mishra P. Bhargava J. Negi A.K. Nath 《Optics & Laser Technology》2007,39(4):800-805
This paper presents an investigation of laser rapid manufacturing (LRM) for Inconel-625 components. LRM is an upcoming rapid manufacturing technology, it is similar to laser cladding at process level with different end applications. In general, laser-cladding technique is used to deposit materials on the substrate either to improve the surface properties or to refurbish the worn out parts, while LRM is capable of near-net shaping the components by layer-by-layer deposition of the material directly from CAD model. In the present study, a high-power continuous wave (CW) CO2 laser system, integrated with a co-axial powder-feeding system and a three-axis workstation were used. The effect of processing parameters during LRM of Inconel-625 was studied and the optimum set of parameters for the maximum deposition rate was established employing Orthogonal L9 array of Taguchi technique. Results indicated that the powder feed rate and the scan speed contributed about 56% and 26%, respectively to the deposition rate, while the influence of laser power was limited to 10% only. Fabricated components were subjected to non-destructive testing (like—ultrasonic testing, dye-penetrant testing), tensile testing, impact testing, metallographic examinations and micro-hardness measurement. The test results revealed defect-free material deposition with improved mechanical strength without sacrificing the ductility. 相似文献
82.
José A. Anquela Teresa Cortés Miguel Gómez-Lozano Mercedes Siles-Molina 《Acta Mathematica Hungarica》2004,103(3):177-196
We investigate the basic properties of the different socles that can be considered in not necessarily semiprime associative
systems. Among other things, we show that the socle defined as the sum of minimal (or minimal and trivial) inner ideals is
always an ideal. When trivial inner ideals are included, this inner socle contains the socles defined in terms of minimal
left or right ideals.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
83.
Govindarajan Sankar A. Sultan Nasar 《Journal of polymer science. Part A, Polymer chemistry》2007,45(8):1557-1570
A series of substituted N‐methylaniline‐blocked polyisocyanates based on 4,4′‐methylenebis(phenyl isocyanate) and poly(tetrahydrofuran) were prepared and characterized thoroughly with FTIR, 1H NMR, and 13C NMR spectroscopy methods. Compared with unsubstituted N‐methylaniline, a blocking agent with an electron‐releasing substituent at the para position took a shorter time, whereas those with an electron‐releasing substituent at the ortho position or an electron‐withdrawing substituent at the ortho and para positions took longer times for the blocking reaction. The thermal dissociation reactions of blocked polyisocyanates were carried out with an FTIR spectrophotometer attached to hot‐stage accessories under dynamic and isothermal conditions. The dynamic method was used to determine the deblocking temperature, and the isothermal method was used to calculate the deblocking kinetics and activation parameters. The cure times of blocked polyisocyanates with hydroxyl‐terminated polybutadiene were also determined. The deblocking temperatures, the results of cure‐time studies, and the kinetic parameters revealed that the thermal dissociation of the N‐methylaniline‐blocked polyisocyanates was retarded by electron‐donating substituents and facilitated by electron‐withdrawing substituents. The action of N‐methylanilines as blocking agents for isocyanate was explained by the formation of a four‐center, intramolecularly hydrogen‐bonded ring structure during the thermal dissociation of the blocked polyisocyanates. The formation of such a hydrogen‐bonded ring structure was confirmed and supported by variable‐temperature 1H NMR studies and entropy parameters, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1557–1570, 2007 相似文献
84.
数码相机原理与系统设计研究 总被引:7,自引:0,他引:7
介绍了数码相机的工作原理 ,分析了数码相机的系统结构 ,提出了设计数码相机的处理流程。典型的数码相机系统有镜头、闪光灯、光学取景器、LCD显示屏、图像数据存储扩展设备接口、图像数据传输接口、供电系统以及核心处理器等八个主要模块。数码相机的数据流向从图像传感器开始 ,止于图像数据的存储和传输。数据流的处理主要包括模数转换、光学黑电平钳位、针对镜头的边缘畸变的运算修正、坏像素处理、白平衡处理、伽马校正、色彩合成处理、边缘检测 (锐度检测 )和伪彩色检测 (伪彩色抑制 )、JPEG压缩和图像存储器等模块 相似文献
85.
This paper studies the problem of how changes in the design of the genetic algorithm (GA) have an effect on the results obtained in real-life applications. In this study, focused on the application of a GA to the tuning of technical trading rules in the context of financial markets, our tentative thesis is that the GA is robust with respect to design changes. The optimization of technical trading systems is a suitable area for the application of the GA metaheuristic, as the complexity of the problem grows exponentially as new technical rules are added to the system and as the answer time is crucial when applying the system to real-time data. Up to now, most of GAs applications to this subject obviated the question of possible “design dependence” in their results. The data we report, based on our experiments, do not allow us to refute the hypothesis of robustness of the GA to design implementation, when applying to technical trading systems tuning. 相似文献
86.
87.
88.
Aït Hmaïdouch L. Mançour Billah S. El Hadek M. 《Journal of Thermal Analysis and Calorimetry》2002,69(2):659-667
The solid—liquid equilibria of the ternary system H2O—Al(NO3)3—Mg(NO3)2 were studied at –30, –20, –10 and 0°C by using a synthetic method which allows to detemine all the characteristic points of isothermal sections. The stable solid phases which appear are respectively: ice, Al(NO3)3·9H2O, Mg(NO3)2·9H2O and Mg(NO3)2·6H2O. Neither double salts nor mixed crystals are observed in the temperature and composition field studied. Polytherm diagram layout show two invariant transformations correspond with an eutectic point and a peritectic point.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
89.
本文针对单件小批量生产系统 ,建立了模糊优化的动态随机投入产出模型 ,同时给出了该模型的递推解法 ,并用此模型对某单件小批企业在生产计划期的商品量进行了规划 相似文献
90.