Optimum design of an extended octagonal ring by goal programming

Extended octagonal rings are used in metal cutting dynamometers to measure cutting forces and torque. The controllable design variables are the thickness, radius and width of the ring. Normally the objectives of the design are to achieve high sensitivity and high rigidity which arc conflicting in nature. Therefore, both requirements cannot be achieved simultaneously. The goal programming technique is used to determine the optimum size of extended octagonal ring for various goal priorities with respect to sensitivity and rigidity     

Dynamic modelling using neural networks

A neural network structure is presented that uses feedback of unmeasured system states to represent dynamic systems more efficiently than conventional feedforward and recurrent networks, leading to better predictions, reduced training requirement and more reliable extrapolation. The structure identifies the actual system states based on imperfect knowledge of the initial state, which is available in many practical systems, and is therefore applicable only to such systems. It also enables a natural integration of any available partial state-space model directly into the prediction scheme, to achieve further performance improvement. Simulation examples of three varied dynamic systems illustrate the various options and advantages offered by the state-feedback neural structure. Although the advantages of the proposed structure, compared with the conventional feedforward and recurrent networks, should hold for most practical dynamic systems, artificial systems can readily be created and real systems can surely be found for which one or more of these advantages would vanish or even get reversed. Caution is therefore recommended against interpreting the suggested advantages as strict theorems valid in all situations.     

False topography perception phenomena and its correction

The remote sensing data of a rugged terrain always suffer from topographic effects and, in such cases people frequently perceive valleys as ridges, and vice versa in the optical imagery of Sun-synchronous satellite. The appearance of inverse topography can be termed as false topography perception ( FTP) FTP has been observed in various satellites images such as Landsat, IRS, and SPOT The problem of FTP becomes more severe in high altitude areas of hilly terrain, such as Himalayan terrain. FTP is usually caused by the combination of various interrelated factors; among them are topographic relief, Sun elevation, the azimuth angle, viewing angle, and hatching or engraving features present on the slopes. Once satellite data of rugged terrain are acquired, then all FTP-influencing factors are fixed, except for the viewing angle of the observer. Hence, the correction of FTP becomes straightforward. There are two ways to correct satellite dala for FTP effects: ( a) rotate the image by between 135° -180° i.e changing the viewing angle of the observer; or (b) inverse the image data by making a negative of the whole image (255-image) which will bring change in the Sun' s illumination by 1807deg; The present paper discusses the FTP phenomena and its causes, and suggests methods of correction.     

为进行能源管理并强化车体结构所采用的结构胶黏剂

结构胶黏剂是汽车制造过程中一种日趋重要的金属连接方式。介绍了汉高公司开发的一种汽车用结构胶黏剂的性能特点及应用工艺要求。通过实验证明结构胶黏剂对于提高车体结构性能、减轻车体质量、简化生产过程和优化生产成本来说,是一种十分有用的材料。     

Oxygen Activity Dependence of the Electrical Conductivity of Li-Doped Cr2O3

The electrical conductivity of Li-doped Cr₂O₃ was investigated as a function of PO₂, temperature, and dopant content. Results show that the electrical conductivity remains almost unchanged with decreasing P O₂ in the high-P O₂ region but decreases rapidly at low P O₂. A second phase was found in samples which contained more than 0.85 mol% Li. The results are explained by a model in which the concentration of charge carriers is dependent on the acceptor dopant and oxygen vacancy concentration.     

富氮气调——磷化氢的可供替换技术（中英文）

在粮食储藏上利用氮气的方法已经有30 多年的历史,但直到最近经济有效的变压吸附（PSA）和膜分离（MS）制氮设备的出现,才使得该技术在储粮上使用成为可能。本研究首先在25、30和35 ℃、99%、98%和97%氮气的环境下,对小麦、大麦、燕麦、羽扇豆和油菜籽中的花斑皮蠹、赤拟谷盗、谷蠹和米象成虫和非成虫虫态进行了为期4、3和2周的实验室生物测定。然后在终端用户Lake Grace和CBH（Cooperative BulkHandling）谷物进出口公司Albany 出口港码头开展实仓验证,测定小麦、大麦和油菜籽中不同储粮害虫虫种和油菜籽瓢虫和肖叶甲类两种田间害虫的防治效果。同时对处理后的粮食品质进行了测定。实验结果表明,害虫死亡率随着氧气浓度降低、暴露时间和温度的增加而增加,富氮低氧在低温条件下不能100%致死花斑皮蠹幼虫。氮气处理对磷化氢抗性和敏感品系储粮害虫防治效果没有差异。与其他粮种相比,在油菜籽中的防治效果更好。各种粮种的水分含量、蛋白质、含油量、淀粉和籽粒颜色品质指标均未受到影响。成功开发了富氮低氧商业规模应用模式,为磷化氢高抗性害虫治理提供了解决方案,满足市场日益增长对无害虫和无化学残留粮食的需求。     

Nanostructured coatings for super hydrophobic textiles

The promising aspects of nanocomposite coatings to mimic the nano roughened self cleaning surface of lotus leaf is explored in this paper. A detailed study on nanosilica and clay based nanocomposite coatings using dip coating and layer by layer self assembly (L–b–L) is being described where lotus leaf effect has been mimicked on the cotton fabric surface using these particles as they develop nanosized surface roughness which helps to produce a super-hydrophobic surface. Nanosilica performs better in creating nano roughness on cotton fabric wherein the contact angle is ${>}$ 150 $^{\circ}$ . The water contact angle of 2 wt% fluoro emulsion (Nuva HPU) treated cotton fabric increases from 115 $^{\circ}$ to 155 $^{\circ}$ when the fabric is pretreated with 0 ${\cdot} $ 5 wt% nanosilica emulsion. The water repellency rating of fabric treated with 0 ${\cdot }$ 16 wt% nanosilica along with 2 wt% Nuva HPU is comparable to that of 4 wt% Nuva HPU treated cotton fabric. On the other hand, 40 bilayers of nanosilica need to be applied on cotton fabric surface through L–b–L technique to create uniform nano roughening and gives a water repellency rating of 4. The air permeability of L–b–L nanocoated cotton fabric is not adversely affected by the super-hydrophobic nanostructured coating.     

STUDIES ON OCCURRENCE AND CHARACTERIZATION OF CLOSTRIDIUM PERFRINGENS FROM SELECT MEATS

A study was undertaken to assess the prevalence of Clostridium perfringens in meat and to characterize the isolates obtained in the study for virulence factors. A total of 211 meat samples of different animals (70 each of buffalo and goat and 71 of poultry) were screened and the highest occurrence of C. perfringens was observed in goat (91.4%) followed by poultry (70.4%) and buffalo (65.7%). Among the 116 isolates (buffalo‐32, goat‐37 and poultry‐45) of C. perfringens screened for the presence of enterotoxin gene by PCR, 9.3, 32.4 and 15.5% isolates of buffalo, goat and poultry, respectively, were found to possess enterotoxin gene. Screening of 15 enterotoxin gene possessing isolates for verocytotoxicity revealed that 12 isolates exhibited cytopathic effect while 3 isolates did not show any cytopathic effect in spite of the presence of enterotoxin gene. A total of 115 C. perfringens isolates were screened for other virulence markers, i.e., lecithinase and hemolysin. The results revealed that the majority of the isolates expressed these activities. Antibiogram studies of C. perfringens isolates using 16 antibiotics displayed multidrug resistance. The isolates showed resistance to streptomycin, ceftazidime, colistin sulfate, cephalothin, ampicillin and gentamicin. Whereas 100% sensitivity to ciprofloxacin, ofloxacin and nitrofurantoin was seen, moderate sensitivity was observed with tetracycline and sulfatriad.     

Time domain analysis of a current source inverter

A single phase current source inverter feeding an inductive load is analysed in detail, and design criteria for the inverter are worked out. It is found that the commutating capacitance needed is proportional to the square of turn-off time of the thyristors and a low commutating capacitance will permit the circuit operation for higher frequencies.