计算机控制渗碳的工艺设计

本文叙述了在计算机控制渗碳的下，如何正确输入工艺参数，尤其是选择适当的工艺曲线和相应的强渗／扩散的比例，以期获得理想的碳浓度分布。     

United States pharmacopeia safety evaluation of spirulina

The Dietary Supplements Information Expert Committee (DSI-EC) of the United States Pharmacopeial Convention (USP) reviews the safety of dietary supplements and dietary supplement ingredients for the purpose of determining whether they should be admitted as quality monographs into the United States Pharmacopeia and National Formulary (USP-NF). The United States Food and Drug Administration (FDA) has enforcement authority to pursue a misbranding action in those instances where a dietary supplement product indicates that it conforms to USP standards but fails to so conform. Recently DSI-EC undertook a safety evaluation of spirulina, a widely used dietary ingredient. DSI-EC reviewed information from human clinical trials, animal studies, and regulatory and pharmacopeial sources and analyzed 31 adverse event reports regarding spirulina to assess potential health concerns. At the conclusion of this review, DSI-EC assigned a Class A safety rating for Spirulina maxima and S. platensis, thereby permitting the admission of quality monographs for these dietary supplement ingredients in USP-NF. DSI-EC continually monitors reports concerning the safety of dietary supplements and dietary supplement ingredients for which USP dietary supplement monographs are developed. The DSI-EC may revisit the safety classification of spirulina as new information on this dietary ingredient becomes available.     

The effectiveness of test-driven development: an industrial case study

Test-driven development (TDD) is a software development practice, where test cases are incrementally written before implementing the production code. This paper presents the results of a multi-case study investigating the effectiveness of TDD within an industrial environment. Three comparable medium-sized projects were observed during their development cycle. Two projects were driven without TDD practice, while the third one introduced TDD into the development process. The effectiveness of TDD was expressed in terms of external code quality, productivity, and maintainability. Our results indicate that the TDD developers produced higher quality code that is easier to maintain, although we did observe a reduction in productivity.     

Compression of power quality event data using 2D representation

This paper introduces the energy compaction efficiency of a novel two-dimensional (2D) representation for compression of recorded power quality event data. The 2D representation enables to exploit redundancy across vertical samples that correspond to samples which are far from each other in time. In one-dimension (1D), compression algorithms are unable to depict the correlation between such far away samples. However, the 2D representation renders statistically related far away samples near to each other in the vertical dimension, hence several transform domain techniques are able to compress such rendered data efficiently. In this paper, using real life sampled power quality event data, wavelet transform energy compaction efficiencies are compared through a basis restriction error analysis and the results are justified by simple and commercially available 1D and 2D wavelet based coders. The preliminary results indicate that the 2D representation provides a significant energy compaction efficiency.     

Condition monitoring of speed controlled induction motors using wavelet packets and discriminant analysis

This work presents an intelligent method for the condition monitoring of induction motors supplied with adjustable speed drives (ASD). Most of the previous work in this area concentrated on the fault detection and classification of induction motors supplied directly from an a.c. line. However, ASD driven induction motors are widely used in industrial processes and therefore obtaining an intelligent tool for the condition monitoring of these motors is necessary in terms of preventive maintenance and reducing down time due to motor faults. Here 3-phase supply side current of the ASD driving an induction motor is used to extract statistical features of wavelet packet decomposition coefficients within a frequency range of interest. This way, the information regarding the output frequency of the ASD and hence the motor speed is not required. Six identical three-phase induction motors were used for the experimental verification of the proposed method. One healthy machine was used as a reference, while other five with various synthetic faults were used for condition detection and classification. Extracted features obtained from decomposition coefficients of different wavelet filter types for all motors were employed in three different and popular classifiers. The proposed method and the performance of the features used for fault detection and classification are examined at various motor loads and speed levels, and it is shown that a successful condition monitoring system for induction motors supplied with ASDs is developed. The effect of selected filter type in wavelet decomposition to the condition monitoring process is analyzed and presented.     

Capacity reservation under supply uncertainty

Shortages of input materials and components used in the production process often adversely influence sales of manufacturing firms. Manufacturers can guarantee delivery of the inputs by initiating capacity reservation arrangements with their suppliers. We study a multi-period capacity reservation contract between a manufacturer and a long-term supplier when there is uncertainty about the quantity of an input item available in the spot market. The contract requires the manufacturer to pay a fixed amount to the supplier at each period. In return, the supplier guarantees availability of the input up to a predetermined level of volume. The manufacturer can also meet some of input needs from a spot market, which may exist in the form of a B2B electronic exchange. Optimal inventory policy for the manufacturer in this dual supplier environment is derived analytically. Numerical examples are used to explore the strategies of the manufacturer and the supplier in certain and uncertain supply environments. We find that uncertain input markets lead to an increase in the share of inputs purchased in advance via long-term contracts. Capacity reservation contracts are shown to increase capacity utilization of the supplier compared to the traditional unit-price based supply contracts.