渐开线内插齿刀的优化设计

介绍了渐开线直齿内齿轮插齿刀的优化设计方法。论述了其数学模型的建立和优化方法的选择,并通过实例验证了优化设计的效果。     

Conversion of allylic hydroxy oleate to conjugated linoleic acid and methoxy oleate by acid-catalyzed methylation procedures

Conjugated linoleic acid (CLA), a term describing a group of conjugated octadecadienoic acids that are both naturally occurring and formed during food processing, is the subject of considerable current research because of the recently reported antioxidant and anticarcinogenic properties of these compounds. Allylic hydroxy oleates (AHOs), secondary products of lipid autoxidation, have also been found in foods. By means of high-performance liquid chromatography with ultraviolet detection, gas chromatography/mass spectrometry and gas chromatography/matrix isolation/Fourier transform infrared spectroscopy, we determined that currently used acid-catalyzed methylation procedures convert AHOs to CLA and other products that potentially yield high values in determination of CLA in foods. A mixture of AHOs, containing mainly (8- and 11-)hydroxy-9-octadecadecenoates, was synthesized and tested by methylation procedures with the following catalysts: BF₃, HCl, NaOMe and tetramethylguanidine. Both the BF₃ and the HCl procedures converted AHOs to CLA. The base-catalyzed procedures did not convert AHOs to CLA.     

Strengths and weaknesses of finite element modeling deep hole drilling as compared with beam and column equations

Deep hole drilling has been studied mainly experimentally in the past. Recently, some theories using beam or column equations have been proposed, which involved complicated mathematical efforts. This work analyzed deep hole drilling by a finite element model (FEM). Results of modal analysis on the established FEM were compared with results from Euler beam equations. Further analysis showed that the FEM could also predict straightness deviation as did the column equation. In addition, FEM could analyze the effects of variable support distance which neither beam nor column equation could. Other analysis results are also presented. The results in this study showed the strength and weakness of the FEM.     

A joint GA+DP approach for single burn-in oven scheduling problems with makespan criterion

This research is motivated by the scheduling problem found in the burn-in operation of semiconductor final testing, where jobs are associated with release times, processing times, and sizes. The burn-in ovens are modeled as batch-processing machines which can process a batch of several jobs as long as the total sizes of the jobs do not exceed the machine capacity, and the processing time of a batch is equal to the longest time among all the jobs in the batch. Moreover, this paper attempts to schedule jobs on a single batch-processing machine to minimize makespan. A joint GA+DP algorithm is proposed involving two stages: (1) the formation of job sequence by genetic algorithm operators, and (2) the formation of batches by a dynamic programming algorithm. Computational experiments are given to examine the performance of the proposed algorithm. The experimental results indicate that the joint GA+DP approach has well improved on all instances with respect to solution quality and runtime.     

Sensitive Faraday rotation measurement with auto-balanced photodetection

A magneto-optic polarimetry based on auto-balanced photodetection is investigated. In this experiment, a commercial auto-balanced photoreceiver is adopted to measure the Faraday rotation of air. With a proper setup to utilize its noise cancellation capability, the measurement can be flexible and sensitive. The angular sensitivity is 2.99×10(-8) rad Hz(-1/2), which is about 2.7 times the shot noise limit. The measured Verdet constant of air is +1.39×10(-9) rad G(-1) cm(-1) at 634.8 nm. Significantly we applied a small AC current to induce the magnetic field, so there was no heating in the coil. In addition, a double current modulation scheme was used to demonstrate that there was no zero drift and amplifier instability in the measurement. The possibility of improvement of the angular sensitivity and the potential applications are also discussed.     

A simulated annealing for hybrid flow shop scheduling with multiprocessor tasks to minimize makespan

This paper studies a hybrid flow shop scheduling problem (hybrid FSSP) with multiprocessor tasks, in which a set of independent jobs with distinct processor requirements and processing times must be processed in a k-stage flow shop to minimize the makespan criterion. This problem is known to be strongly nondeterministic polynomial time (NP)-hard, thus providing a challenging area for meta-heuristic approaches. This paper develops a simulated annealing (SA) algorithm in which three decode methods (list scheduling, permutation scheduling, and first-fit method) are used to obtain the objective function value for the problem. Additionally, a new neighborhood mechanism is combined with the proposed SA for generating neighbor solutions. The proposed SA is tested on two benchmark problems from the literature. The results show that the proposed SA is an efficient approach in solving hybrid FSSP with multiprocessor tasks, especially for large problems.     

周志宏对魏氏组织及马氏体的形成和形貌的早期金相研究

关于铁合金中相变的详尽显微组织方面的早期研究之一是由艾伯特·苏佛教授的学生周志宏（哈佛大学博士，１９２８年）完成的。该项研究描述了铁碳合金中魏氏组织和马氏体的形成，所用合金具有宽的碳含量范围，热处理时采用的冷却速率范围也是宽的。还描述了一种独特的汞浴淬火方法。此研究工作从未完全发表过。本文援引该博士论文中的一些原始显微组织照片和部分原文，并试图用我们现今对于铁合金相变的理解来阐明和重新诠释。文中还包括中国引进现代工业和科学的历史背景，以及周志宏对苏佛教授的个人回忆。     

Resource Portfolio Planning Methodology for Semiconductor Wafer Manufacturing

Resource portfolio planning is a frequent task in semiconductor wafer fabrication plants, as process, machine and product technologies evolve rapidly and the plants go through capacity expansion. As wafer fabrication plants are complex integrated factories with conspicuous queuing effects, portfolio planning must take into consideration machine use, factory throughput, and total flow-time simultaneously. This paper describes a resource portfolio planning methodology for wafer fabrication foundry plants. An improved static capacity model is first presented. A portfolio planning procedure based on static capacity estimation and queuing analysis is next described. This procedure enables the solution space of resource portfolios to be explored effectively and has demonstrated a capability superior to the current planning method in an industry case study. A software implementation of the procedure is also used to clarify planning dilemmas. It is shown that empirical formulae can be used to estimate the efficiency of batch machines. It is also used to show three types of portfolio adjustment action: flow-time reduction, cost reduction and effectiveness improvement.     

Economic Design of Averages Control Charts for Monitoring a Process with Correlated Samples

When an x control chart is used to monitor a manufacturing process, three parameters should be determined: the sample size, the sampling interval between successive samples, and the control limits for the chart. In 1956, Duncan presented the first cost model to determine the three parameters for the x charts, which is called the economic design of x charts. Traditionally, when designing a x chart, it is assumed that the measurements within a sample are independently distributed; however, this assumption may not be tenable. In this paper, we develop the economic design of x charts for correlated measurements within a sample. An example is presented to illustrate the solution procedure. From the results of the sensitivity analyses of this example, we find that if the measurements in the sample are positively correlated, highly correlated data result in a smaller sample size, a frequent sampling interval and narrower control limits; however, if the measurements in the sample are negatively correlated, highly correlated data yield a smaller sample size and narrower control limits.     

Developing a diagnostic system through the integration of ant colony optimization systems and case-based reasoning

This study is dedicated to integrating both the clustering method and case-based reasoning (CBR) for developing a diagnostic system in maintenance. The reason for this is that searching similar cases for CBR is time consuming if the case base is fairly large. It is necessary to cluster the cases into some groups, and then perform the search for the most appropriate possible group. A novel approach, the ant colony system clustering algorithm (ASCA), is employed for this purpose. The main advantage of this technique is the reduction in the amount of time used in comparison. A real-life problem for car maintenance has shown evidence of this advantage as well as its precision ability.