2,119 research outputs found

    Decomposition of manufacturing processes: a review

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    YesManufacturing is a global activity that started during the industrial revolution in the late 19th century to cater for the large-scale production of products. Since then, manufacturing has changed tremendously through the innovations of technology, processes, materials, communication and transportation. The major challenge facing manufacturing is to produce more products using less material, less energy and less involvement of labour. To face these challenges, manufacturing companies must have a strategy and competitive priority in order for them to compete in a dynamic market. A review of the literature on the decomposition of manufacturing processes outlines three main processes, namely: high volume, medium volume and low volume. The decomposition shows that each sub process has its own characteristics and depends on the nature of the firm’s business. Two extreme processes are continuous line production (fast extreme) and project shop (slow extreme). Other processes are in between these two extremes of the manufacturing spectrum. Process flow patterns become less complex with cellular, line and continuous flow compared with jobbing and project. The review also indicates that when the product is high variety and low volume, project or functional production is applied.The financial support by the Malaysian Government, Universiti Malaysia Pahang and Bradford University for this research is gratefully acknowledged

    Novel heuristic for low-batch manufacturing process scheduling optimisation with reference to process engineering

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    YesScheduling is an important element that has a major impact on the efficiency of all manufacturing processes. It plays an important role in optimising the manufacturing times and costs resulting in energy efficient processes. It has been estimated that more than 75% of manufacturing processes occur in small batches. In such environments, processes must be able to perform a variety of operations on a mix of different batches. Batch-job scheduling optimisation is the response to such low batch manufacturing problems. The optimisation of batch-job process scheduling problem is still a challenge to researchers and is far from being completely solved due to its combinatorial nature. In this paper, a novel hybrid heuristic (HybH) solution approach for batch-job scheduling problem is presented with the objective of optimising the overall Makespan (Cmax). The proposed HybH is the combination of Index Based Heuristic (IBH) and the Finished Batch-Job (FBJ) process schedule. The heuristic assigns the first operation to a batch-job using IBH and the remaining operations on the basis FBJ process schedule. The FBJ process schedule gives priority to the batch-job with early finished operations, without violating the constraints of process order. The proposed HybH is explained with the help of a detailed example. Several benchmark problems are solved from the literature to check the validity and effectiveness of the proposed heuristic. The presented HybH has achieved batch-job process schedules which have outperformed the traditional heuristics. The results are encouraging and show that the proposed heuristic is a valid methodology for batch process scheduling optimisation

    Role of serum angiotensin converting enzyme in sarcoidosis

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    This study was conducted to determine the role of Serum Angiotensin Converting Enzyme (SACE) as a marker in the differential diagnosis of pulmonary diseases and prognosis of sarcoidosis, A retrospective analysis of 113 medical records of patients at The Aga Khan University Hospital, with laboratory investigation for SACE was performed. Among 113 patients, 51 cases were found to have sarcoidosis, 44 of them had SACE levels greater than 52 lU/L (mean ACE 104.44). SACE levels were also found elevated in other clinical conditions like tuberculosis (mean 58.64 lUlL), but the enzyme level were less (p0.04) than those found in sarcoidosis (mean (92-97 lUlL). SACE activity was found to be considerably lower in other chronic lung diseases such as, fibrosing alveolitis (mean 43.98 lUlL), interstitial lung disease (mean 42.11 lU/L) and chronic obstructive lung disease (mean 40.85 lUlL). Twenty patients of sarcoidosis, who received steroid tretalment subsequently showed a decline in the SACE levels. SACE is a useful marker in differential diagnosis as 37.2% cases of sarcoidosis compared to only 9.09% of tuberculosis had SACE levels greater than 100 lUlL. In addition, our data also suggest that serum ACE is useful for the diagnosis as well as monitoring prognosis in sarcoidosis (JPMA 48:131,1998)

    Pulmonary infiltrates during chemotherapy-induced febrile neutropenia: incidence, patterns and outcomes

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    OBJECTIVE: To analyze the incidence, etiologies, radiographic patterns, and clinical outcomes of adult leukemics with prolonged febrile neutropenia and pneumonia. METHODS: A retrospective study was conducted at a tertiary care hospital. The medical records of adult patients with acute myeloid leukemia diagnosed between January 1989 and June 2000 and undergoing induction chemotherapy were included. Only the patients who presented with a pulmonary infiltrate, secondary leukemia (e.g., transformed chronic myeloid leukemia underlying myelodysplastic syndrome, or disease following alkylating agent therapy) were included and those developing infiltrates following consolidation chemotherapy were excluded. RESULTS: A total of 124 patients were admitted to the hospital with a diagnosis of AML during the study period. Thirty-one patients were excluded; 93 patients received induction chemotherapy and were included in the study analysis. The median age was 36 years (15 - 70 years); 58 males and 35 females. Sixty two percent patients received Cytosine Arabinoside (Ara-C), 17% received Etoposide, 11% received Ara-C and Mitoxantrone, and 6% received All-trans-retinoic Acid. The mean onset and duration of neutropenia were 5 and 15 days, respectively. Pulmonary infiltrates were identified during 45% of neutropenic episodes. A presumptive causative organism was isolated from 50% of patients with an infiltrate: Gram-positive bacteria were most common (47%) followed by Gram-negative bacilli (33%) and fungi (20%). Survival data were available for 88 patients; median disease free survival for the entire cohort was 7 months. Male sex (p=0.015), onset of neutropenia (p=0.02) and bilateral distribution of an infiltrate (p=0.03) were statistically significant predictors of early mortality. For patients with and without pneumonia, the median disease-free interval and overall survival were 2.5 and 4.6 months and 9 and 13 months (p=0.038 and p=0.095) respectively. CONCLUSION: Neutropenia occurred at a mean of 5.0 after initiation of induction chemotherapy. The majority of patients had bilateral pulmonary infiltrates. Male sex, onset of neutropenia and bilateral distribution of an infiltrate were found to be statistically significant predictors of early mortality
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