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51.
Diwakar Gupta John A. Buzacott 《International Journal of Flexible Manufacturing Systems》1993,5(4):263-286
Consider a firm that could choose either an inexpensive product-specific (dedicated) facility or a costly flexible facility, or a combination of the two, in order to satisfy demand for two product groups. Flexible technology offers benefits of scale and scope economies. However, it may have added operational costs due to the need to have excess capacity (to permit changeovers) and to maintain cycle stocks. As a consequence, the economic viability of flexible technology is significantly affected by the choice of the operating doctrine. This article presents first-pass decision models to help the firm choose the optimum sizes of facilities and the degree of flexibility for the flexible facility such that the contingent operational costs are simultaneously optimized. Two variations of the problem are considered. Whereas, the first applies to a situation in which the demand rates are constant and predictable, the second considers random demands. In each case, this study provides a formulation of the problem, structural results, and the sensitivity of the results to cost parameters. These results have modest data and computational requirements, making them suitable for first-cut attempts at narrowing available choices.This research has been supported by the Natural Sciences and Engineering Research Council of Canada through operating grants to the authors. 相似文献
52.
20 cardiac patients with the clinical and radiological signs of heart failure were treated alternately intravenously and orally with proscillaridin-4'-methyl ether in a 2-period change-over procedure. With medium rate full saturation a steady state was maintained under observation of electrocardiographic parameters. The maintenance dose was determined to be 1.00 mg intravenously and 1.71 mg orally. Thus, relative enteral availability was 60%. In 70% of patients cardiac recompensation could be reached only by treatment with proscillaridin-4'-methyl ether. In 9 of 20 patients undesirable side effects consisted of laxative effects. 相似文献
53.
This paper deals with studies on the dilute solution properties of methyl methacrylate—acrylonitrile copolymer of 0.289 mole fraction (mf) of acrylonitrile composition. Mark—Houwink parameters for this copolymer have been evaluated in acetonitrile (MeCN), 2-butanone (MEK), dimethylformamide (DMF) and γ-butyrolactone (γ-BL). The solvent power is found to be in the order of MEK < MeCN < DMF < γ-BL at 30°C. Herein, probably for the first time, the steric factor for the copolymer is found to be lower than that for the parent homopolymers and the excess interaction parameter, χAB is found to be negative. This probably suggests that the units are compatible to each other. 相似文献
54.
This study deals with the parameter estimation in long-memory time series models. An unbiased and consistent estimator is proposed. The proposed estimator is based on a least-squares method in the frequency domain, and it is computationally simple. Also, the Cramer–Rao lower bound is derived. The mean-square error of the proposed estimator is order of O(1/N), where N is the number of samples. The accuracy of the estimates is verified using synthetic long-memory time series data. 相似文献
55.
G. S. Toteja S. Diwakar A. Mukherjee P. Singh B. N. Saxena R. L. Kalra S. K. Kapoor H. Kaur R. B. Raizada Vasudha Singh R. C. Vaidya S. Chakraborty S. B. Shirolkar A. Regupathy Douressamy 《Food Additives & Contaminants》2006,23(3):281-288
Under a multicentre study conducted by the Indian Council of Medical Research, 1712 samples of wheat grain/flour were collected from urban and rural areas in 11 states representing different geographical regions of India. These samples were analysed for residues of DDT (2,2-bis (p-chlorophenyl)-1,1,1-trichloro ethane) and different isomers of HCH (1,2,3,4,5,6-hexachloro cyclohexane, a mixture of isomers) by gas-liquid chromatography. Residues of DDT were detected in 59.4% of 1080 samples of wheat grain and in 78.2% of 632 samples of wheat flour. Different isomers of HCH were present in about 45-80% of the samples of wheat grain/flour. Medians of DDT and total HCH, respectively, for pooled samples of wheat grain were 0.013 and 0.035 mg kg-1, while those for wheat flour were 0.01 and 0.02 mg kg-1. Estimated daily intakes of DDT and different isomers of HCH through the consumption of wheat contaminated at their median and 90th percentiles constituted a small proportion of their acceptable daily intakes. Amongst the pesticide residues analysed, statutory maximum residue limits have been fixed only for γ-HCH in wheat in India, as 0.1 mg kg-1 in wheat grain and zero in wheat flour. Residue levels of γ-HCH exceeded these maximum residue limits in five of 1080 samples of wheat grain and in 340 of 632 samples of wheat flour. The failure to meet the requirement of the γ-HCH maximum residue limit in large number of wheat flour samples was attributed to the fixation of practically unachievable zero limit. Comparing the previous studies and the present one, the levels of residues of DDT and HCH in wheat were significantly decreased. 相似文献
56.
Maximum likelihood identification of stochastic linear systems 总被引:1,自引:0,他引:1
The maximum likelihood estimation of the coefficients of multiple output linear dynamical systems and the noise correlations from the noisy measurements of input and output are discussed. Conditions are derived under which the estimates converge to their true values as the number of measurements tend to infinity. The computational methods are illustrated by several numerical examples. 相似文献
57.
58.
Bastihalli Tukaram Diwakar Pinto Kumar Dutta Belur Ramaswamy Lokesh Kamatham Akhilender Naidu 《Journal of the American Oil Chemists' Society》2010,87(5):539-548
Garden cress (Lepidium sativum L.) is an edible, underutilised herb, grown mainly for its seeds in India. Physicochemical properties, minor components (unsaponifiable
matter, tocopherols, carotenoids), fatty acid composition and storage stability of garden cress seed oil (GCO) were studied.
Cold press, solvent and supercritical CO2 extraction methods were employed to extract the oil. The total oil content of garden cress (GC) seeds was 21.54, 18.15 and
12.60% respectively by solvent, supercritical CO2 and cold press methods. The physical properties of GCO extracted by the above methods were similar in terms of refractive
index, specific gravity and viscosity. However, cold pressed oil showed low PV and FFA compared to the oil extracted by other
methods. α-Linolenic acid (34%) was the major fatty acid in GCO followed by oleic (22%), linoleic (11.8%), eicosanoic (12%),
palmitic (10.1%) erucic (4.4%), arachidic (3.4%) and stearic acids (2.9%). Oleic acid (39.9%) and α-linolenic acid (42.1%)
were the predominant fatty acids at the sn-2 position. The total tocopherol and carotenoid content of GCO was 327.42 and 1.0 μmol/100 g oil, respectively. The oil was
stable up to 4 months at 4 °C. Tocopherol and BHT offered the least protection, while ascorbyl palmitate (200 ppm) offered
the maximum protection to the oil, when subjected to the accelerated oxidative stability test. Thus GCO can be considered
as a fairly stable oil with a high content of α-linolenic acid. 相似文献
59.
Yogesh S. Kashyap Ashish Agrawal P.S. Sarkar Mayank Shukla Tushar Roy Amar Sinha 《NDT & E International》2011,44(1):41-46
We have used the contrast transfer function based X-ray phase retrieval technique for phase retrieval studies on a two-component system. Pyro-carbon coated alumina matrix was chosen as a two-component system for these studies. Simulations as well as experimental results are presented. This paper shows that X-ray phase contrast along with phase retrieval can become an alternative tool for non-destructive characterization of these materials. We have also attempted to retrieve the spatial distribution of the projected thickness map of the two different elements. 相似文献
60.
G. Jagan Reddy N. Srinivasan Amol A. Gokhale B.P. Kashyap 《Journal of Materials Processing Technology》2009,209(18-19):5964-5972
The hot deformation behavior of spray formed + HIPed Al–Li (UL40) alloy was studied using processing map technique. The map has been interpreted in terms of the microstructural processes occurring in situ with deformation, based on the values of a dimensionless parameter η which is an efficiency index of energy dissipation through microstructural processes. An instability criterion has also been applied to demarcate the flow instability regions in the processing map using another parameter (ξ). Both the parameters (η and ξ) were computed from the experimental data generated by compression tests conducted at various temperature and strain rate combinations over the hot working range (375–575 °C and 3 × 10−4 to 1 s−1) of the present material. The processing map exhibits three distinct η domains without any unstable flow conditions under the investigated temperature and strain rate conditions. The dominant microstructural mechanisms corresponding to these domains were identified to be extended dynamic recovery, grain boundary cavitation and flow localization. The stress–strain, microstructure and hot ductility recorded under the deformation conditions of these domains were correlated to the microstructural processes. The ‘safe window’ for hot working of HIPed UL40 material has been identified based on these results. Further, the significance of HIPing on the hot workability has been enunciated by comparing the results of the present material with the as-spray formed material. 相似文献