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21.
This paper presents a methodology for the estimation of temperature dependent heat transfer coefficient for a vertical rectangular fin by using the inverse heat transfer method with Liquid crystal thermography (LCT) data. Steady state, laminar natural convection experiments have been done on a vertical rectangular fin of size 150 × 250 × 4, (L × w × t, all dimensions are in mm). The variation of heat transfer coefficient is considered as a power law function of temperature excess (h = aoθb) and is derived from the basic Nusselt number equation used for laminar natural convection, Nu = aRab. With this functional form, the one dimensional fin equation in finite difference form is repeatedly solved using the Gauss–Seidel iterative method. Treating this as a one parameter estimation in ‘a’ the sum of the squares of the difference between the simulated and Thermochromic Liquid Crystal (TLC) measured temperatures is minimized with the Golden section search algorithm to retrieve ‘a’. Estimate of ‘a’ and the accompanying uncertainties are first reported for synthetically generated temperature distribution for assumed values of ‘a’. The effect of noise on the estimate of ‘a’ is discussed. This is followed by retrievals with experimentally obtained TLC temperature distribution for a range of heat inputs to the fin base. The required temperature distributions for accomplishing the retrievals over the surface are obtained using calibrated R40C5W Thermochromic Liquid Crystal (TLC) sheets. As an additional proof of the accuracy of the method, the retrieved value of ‘a’ is used to simulate the temperature distribution in the fin which is then compared with the actual TLC measured temperature distribution. 相似文献
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A. V. Ramana Reddy G. Ranga Mohan D. Ravinder B. S. Boyanov 《Journal of Materials Science》1999,34(13):3169-3176
The dielectric constant () and complex dielectric constant () of zinc substituted cobalt ferrites have been measured at room temperature in the high frequency range 100 kHz to 1 MHz. The values of dielectric loss tangent (tan ) have been computed from and . Plots of dielectric constant () versus frequency show a normal dielectric behaviour of the spinel ferrites. The frequency dependence of dielectric loss tangent (tan ) is found to be abnormal, giving a peak at certain frequency for all the ferrites under investigation. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. The dielectric constant for these mixed ferrites is approximately inversely proportional to the square root of the resistivity. A plot of dielectric constant versus temperature shows a transition near the Curie temperature. An attempt is made to explain the possible mechanism for this observation. 相似文献
24.
This article extends the analysis of an earlier paper by the authors for a single product to lot size determination for manufacturing cycles of multiple products. The effects of production breaks, learning interactions due to commonality of tasks and different learning rates for products are considered in the formulation of an equation for the average production time per unit. The equation is applied to an equal lot size per product model. An analysis of a model restricted to equal production intervals per product per cycle is also presented. A sample problem is solved to demonstrate the application of the effects of learning to multiple product lot size determination. 相似文献
25.
Joseph G. Davis E. Subrahmanian Suresh Konda Helen Granger Michael Collins Arthur W. Westerberg 《Information Systems Frontiers》2001,3(3):377-392
The provision of computer support for collaborative work is a central concern for Information Systems (IS) research and practice. In this paper we present the details of an information flow study undertaken in the household division of a large European design and manufacturing company (Delta). The goal of the study was to elicit user requirements for a computer system to facilitate the collaborative work of new product design teams. These requirements form the basis for the design and development of a Web-based LIRÉ (Living Repository) prototype system, the functionalities, features, and rationale of which are discussed. We also present the results of the evaluation of LIRÉ by the users at Delta and our observations on enhancing the sophistication and usefulness of this class of system. A production version based on the prototype but using commercially available software is currently in use by the New Product Development group at Delta. 相似文献
26.
C.P. Kaushik Ravinder Tuteja Namrata Kaushik J.K. Sharma 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,155(1-2):234-240
The work is carried out to minimize the organic chemical load (unexhausted dye contents) in direct dyes effluent using low cost adsorbents. The studies are made with different direct dyes, i.e. Direct Red 28, Direct Yellow 12, Direct Orange 26 and Direct Blue 1 with various adsorbents. Three different bio/natural materials have been selected as adsorbents. These includes, Sugarcane bagasse pith (SB), Saw dust (SD)—the plant origin products, and Brick powder (BP)—a silica based material obtained from earth's crust on thermal heating. These substances are almost discarded waste products with the possibility of use as adsorbents. Experimental work for the dye removal from the effluent by activated charcoal (AC) has also been carried out and the results are compared with other adsorbents. The amount of unexhausted organic dye present in the effluent is measured as chemical oxygen demand (COD) before and after the treatment. Adsorbent Sugarcane bagasse pith shows good performance as compared to Saw dust and Brick powder. For understanding the behaviour of adsorbents Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) has also been carried out. 相似文献
27.
Silicon - In this article, a Heterogeneous Gate-Dielectric Nanosheet Tunnel Field Effect Transistor (HD-NSH-TFET) with three channels is investigated using the 3-D Visual TCAD simulator. The HD... 相似文献
28.
Ravinder Nath 《Behaviour & Information Technology》1992,11(1):24-31
More and more organizations are seeking innovative ways to use information technology (IT) for strategic advantage. One way to gain this competitive edge is by differentiating the services provided to customers. This paper provides a framework to identify areas ripe for the implementation of IT to enhance and improve customer service. The framework is based upon the examination of the existing service delivery system of an organization and how applications of IT might change the interfaces among the various players (customers, employees, etc.) in the service delivery system. Further, examples are presented to illustrate how some organizations have achieved superior service quality by creatively utilizing simple IT tools. 相似文献
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Niels D. Naimon Jerzy Walczyk James S. Babb Oleksandr Khegai Xuejiao Che Leeor Alon Ravinder R. Regatte Ryan Brown Prodromos Parasoglou 《Magma (New York, N.Y.)》2017,30(3):281-289