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- Aardal, Karen, et al.
(författare)
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Decomposition principles applied to the dynamic production and work-force scheduling problem
- 1987
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Ingår i: Engineering Costs and Production Economics. - 0167-188X .- 1878-4011. ; 12:1-4, s. 39-49
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Tidskriftsartikel (refereegranskat)abstract
- One of the most important problems in the production and inventory planning field, is the scheduling of production and work force in a dynamic environment. Although this problem can be formulated as a linear program, it is often quite difficult to solve directly, due to its large scale. Instead, it might be fruitful to use a decomposition approach. Decomposition, in general, means decomposing a difficult problem into several easier, or a sequence of easier problems which are later coordinated to reconstruct the original problem.In this report we discuss several possibilities of applying the most common decomposition principles, namely Benders (primal) and Datnzig-Wolfe (dual), as well as a relatively new decomposition method, called cross decomposition, to the dynamic, multiproduct production and employment planning problem. A number of special cases are also presented.
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| 2. |
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| 3. |
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| 4. |
- Abeysekera, John D.A., et al.
(författare)
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Ergonomics assessment of selected dust respirators : their use in the tropics
- 1987
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 18:4, s. 266-272
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Tidskriftsartikel (refereegranskat)abstract
- The suitability and effectiveness of four different types of British made respirators were studied with respect to comfort, convenience and fit on wearers in Sri Lanka (a developing country). Objective and subjective assessments were made to evaluate the degree of discomfort and interferences to the use of senses. The study revealed that factors such as breathing resistance, work-rate and activity period affected the physiological responses. The weight of the respirator and the skin temperature had no direct relationship with the cardiovascular stress. Positive-pressure respirators that gave lower face temperatures than negative-pressure masks gave this type of respirator an additional advantage in hot environments. Respirators that restricted jaw movement affected the speech intelligibility of the wearer. Orinasal masks restricted vision more than the other types. The problem of fit was found negligible though head and face dimensions significantly differed between the British and the Sri Lankans. Subjective assessment correlated well with objective tests.
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| 5. |
- Abeysekera, John D.A., et al.
(författare)
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Ergonomics of technology transfer
- 1987
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141 .- 1872-8219. ; 1:4, s. 265-272
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Tidskriftsartikel (refereegranskat)abstract
- It is beyond doubt that high technology has elevated the standards of living of mankind. The modern technology created and developed to a great extent by Western or developed societies is now in great demand in Eastern and developing societies who are trying to leap-frog towards advancement. But unfortunately, in the transfer of technology, both the giver and the receiver seem to make many mistakes. A technology transferred without considering the ethnic variables in the societies and differences in the climates, has found to cause problems to the acquirer. Due to the basic human factor differences such as sizes of people, physical environment, physical capacities and organizational and cultural differences, a technology which is unadapted has found to be inappropriate, harmful, hazardous and unsuccessful. In the areas of health, working conditions, production and finance, undesirable effects have resulted through haphazard technology transfer, For a successful transfer, it is therefore stressed that technology has to be adapted or modified taking into consideration the technological, anthropological and socio-economic factors of the acquiring population
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| 6. |
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| 7. |
- Aleksandrovski, A. N., et al.
(författare)
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Anomalies of the plastic deformation of solid parahydrogen
- 1987
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Ingår i: Soviet Journal of Low Temperature Physics. - 0360-0335. ; 13:10, s. 623-624
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Tidskriftsartikel (refereegranskat)abstract
- The work hardening curves σ(ε) of special-purity parahydrogen single crystals are obtained in the temperature range 2-6 °K at very low stresses (σ=5 10 - 2 g/mm2). Our study reveals a number of anomalies, in particular an effect whereby a sample recovers its dimensions after plastic deformation reaching 7%. The work hardening curves of solid neon are also obtained for comparison. The gravity-induced downward flow of parahydrogen single crystals at helium temperatures mentioned in the literature has not been observed.
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| 8. |
- Arén, Björn, et al.
(författare)
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Die tool dimensioning by finite element method
- 1987
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Ingår i: Powder Metallurgy. - : Informa UK Limited. - 0032-5899 .- 1743-2901. ; 30:2, s. 87-96
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Tidskriftsartikel (refereegranskat)abstract
- Stress and strain are studied using the finite element method in the dimensioning of prestrained die tools for powder compaction. The die geometry has been varied and the die has also been subjected to different types of load. The study shows that the mean pressure transverse to the pressing direction is a dimensioning factor, but that the distribution itself is not very important. For a linear pressure distribution, the stress and strain within the die will differ little from results produced under the assumption of an exponential pressure distribution. Attention is also paid to the possibilities of treating the three-dimensional situation in a real die by different methods of two-dimensional FEM analysis
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| 9. |
- Axsäter, Sven, et al.
(författare)
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Combining items for lot sizing in multi-level assembly systems
- 1987
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 25:6, s. 795-807
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Tidskriftsartikel (refereegranskat)abstract
- Many manufacturing firms are faced with the problem of planning the production/purchase quantities for items in single product, multi-level assembly production/inventory systems. Such systems are characterized by a single product, or end item, used to satisfy customer demand, which is assembled from a number of component items which, in turn, may be assembled from one or more other component items, etc. Component items may be either fabricated or purchased. This paper identifies conditions on the cost parameters which, when applicable, allow items to be combined for purpose of optimization, thereby reducing the size of the problem.
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| 10. |
- Axsäter, Sven
(författare)
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Extension of the extended basic period approach for economic lot scheduling problems
- 1987
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Ingår i: Journal of Optimization Theory and Applications. - 0022-3239 .- 1573-2878. ; 52:No 2, s. 179-189
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of choosing cyclical production patterns for several products which are produced on a common production facility. The extended basic period approach of Elmaghraby is extended by allowing more than two basic periods. The problem of dimensionality of the dynamic programming formulation is dealt with by aggregating the capacity data in different basic periods
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