acm - an acm publication

2007 - November

  • A guide for project-based manufacturers and secrets for software buyers

    Most systems have their heritage in the Material Requirements Planning (MRP) philosophy developed in the 1960s. This concept utilized computer power to calculate time-phased material requirements. It later evolved into MRPII promoted by APICS and Ollie Wight during the 1980s, and further evolved to the Enterprise Resource Planning (ERP) systems available today.

    The original premise of all of these systems is that material planning is the center of the universe. The typical manufacturing system was designed with an MRP process at the heart of the system. The emphasis of such systems is on standard bills and routings and standard costs.

    Companies in the ETO world have different requirements. Designing and building complex products to exact customer specifications frequently involves long lead times and heavy engineering content. To win business, you must provide accurate estimates and quotations to a demanding customer base. Unlike the majority of manufacturers, capital equipment manufacturers typically purchase material to a specific project or job. You need to do progress billing and collect actual costs to projects. Often, you will not receive payment for a project until it is installed and operating at a customer's site. So, cash management is of vital importance. And after the sale, you need to track warranty information and provide aftermarket services, including the sale of spare parts that may constitute a significant share of your company's business.

  • New design of the miniature microstrip antennas for mobile communications

    The aim of this paper is to study the miniature patch antenna (patch antenna λ/8) fed by a coaxial line, and the design comparison of this antenna by two methods: The Transmission Line Model (TLM) and the G-L-C Parallel Circuit Model. An adaptation of the microstrip antenna λ/8, by the setting up of a capacitor in the middle of the probe-feed is achieved.

    The modeling and the design of the miniature patch antenna will be made by the TLM; a particular attention will be carried on the results got on the level of the bandwidth. The second part is based on the idea of microstrip patch antenna starting from the G-L-C Parallel Circuit Model, (by order of 14 %), which gives the bandwidth more interest than in the first method (TLM).

    The results obtained by the two methods (Input Impedance, reflection coefficient, SWR and bandwidth) will be given by the programs in MATLAB software.

  • Understanding dependable computing concepts

    This work aims to visually describe the important concepts of a dependable computing system and the relationships between the concepts. The concept map here for dependable computing system concepts would help us for easier and meaningful understanding of this emerging important research topic of computer science and engineering. Readers here won't feel tired of reading long text horizontally lines after lines for conceptualizing this much research and interesting topic.