1,720,963 research outputs found
The hierarchical frame of enterprise activity Modeling (HF-EAM)
No full textThe description of enterprise activities is the basis for process improvement and the building of information systems. To describe such activities, it is necessary to model all enterprise activities from an abstract level to a system building level in a stepwise and integrated manner. Many of the existing methods are limited in their ability to do this. To cope with these problems, this study proposes the hierarchical frame of enterprise activity modeling (HF-EAM) which is composed of five modeling levels from an abstract level to a system building level: function level, process level, task level, document workflow level, and event flow level. At each level, activity's semantics, characteristic, relation, and schema are clearly defined. The rules for stepwise and integrated activity modeling are then exemplified with the industrial application of the HF-EAM. In addition, comparisons with other modeling methods are made in order to deliberate the pros and cons of the HF-EAM
Substrates transformation in a biological excess phosphorus removal system
No full textIn this research, investigations were made on the effects of organic substrate types and their load on phosphorus release. Reactors of three different sizes were operated, being fed on five kinds of organic substrates. The quantitative analyses were made on phosphorus release and substrate utilization under anaerobic condition. The molar ratios of the uptaken organic substrate to the released phosphorus were 0.5 with acetate, 0.6 with glucose, 0.8 with glucose/acetate, and 1.2 with glucose/acids, respectively. The phosphorus release was inhibited at the higher organic load than the steady state organic load. Both acetate and acids/glucose enhanced phosphorus release as well as uptake rate, however, the complete phosphorus removal was achieved after the complete microbial adaptation to the environment. With acetate, operation was hampered by the poor sludge settleability and phosphorus was not uptaken enough though the high phosphorus release was effective. With milk/starch, the phosphorus release and uptake were well developed even though phosphorus release was not comparatively high. From these observations, organic substrates, such as glucose seemed to convert into fatty acids after fast biosorption, and concurrent uptake of these acids by excess phosphorus removing bacteria followed. (C) 1997 Elsevier Science Ltd
On identifying and estimating the cycle time of product development process
No full textA timely introduction of a new product has become invaluable to the firm since the competitors are capable of introducing new or similar products once the driving technology becomes available. In order to generate a high profit from a new product, managers in other departments, such as marketing and production, have to plan ahead of time so that a seamless series of operations can be executed from product development to mass production. Needless to say, a competitive edge is given to the firm with better knowledge on product development process. Such knowledge, nonetheless, is not easy to acquire since a typical product development process is a complex network of many relationships among activities, which we call patterns. In addition to its complex topology, the product development process is often uncertain, iterative, and evolving over time; therefore, even studying individual islands of relationships (patterns) is challenging. Although there were some existing models that shed lights on some of these patterns, very little has been done to systematically analyze the product development process as a whole. In this paper, we develop analytical models that capture essential properties, including uncertainty, iteration and evolution, and estimate the cycle time of each pattern. With our proposed models, the cycle time of a set of patterns (or the whole product development process) can be effectively estimated. As demonstrated in a case study, our model provides valuable insights on how product development process progresses over time, while, the corresponding time estimate can help managers to set appropriate manufacturing and marketing strategies
Heuristics for a tool provisioning problem in a flexible manufacturing system with an automatic tool transporter
No full textThis paper considers a tool provisioning problem in a flexible manufacturing system (FMS) with an automatic tool transporter. The problem considered here is that of determining the number of copies of each tool type for a limited budget with the objective of minimizing makespan, This problem should be solved to decide the (additional) purchase of required tools when the FMS should be reconfigured due to change of part mix. To solve the problem, two heuristic algorithms are proposed. One is a composite search algorithm based on two greedy search methods, and the other is a search algorithm in which numbers of tool copies are determined based on tool groupings. In both algorithms, simulation results are used to find search directions. Computational experiments show that the latter search algorithm gives better results
Due-date based scheduling and control policies in a multiproduct semiconductor wafer fabrication facility
No full textThis paper focuses on lot release control and scheduling problems in a semiconductor wafer fab producing multiple products that have different due dates and different process flows, For lot release control, it is necessary to determine the type of a wafer lot and the time to release wafers into the wafer fab, while it is necessary to determine sequences of processing waiting lots in front of workstations for lot scheduling. New dispatching rules are developed for lot release control and scheduling considering special features of the wafer fabrication process. Simulation experiments are carried out to test the dispatching rules, Results show that lot release control and lot scheduling at photolithography workstations are more important than scheduling at other workstations, Also, it is shown that new dispatching rules work better in terms of tardiness of orders than existing rules such as the EDD (earliest due date) rule and other well-known dispatching rules for multimachine scheduling
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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