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81.
S. Bhattacharya C. Gomez A. Soltanzadeh F. Taghipour C. P. J. Bennington G. A. Dumont 《加拿大化工杂志》2010,88(2):295-305
Agitated pulp stock chests are the most widely used mixers in pulp and paper manufacture. Stock chests are used for a number of purposes, including attenuation of high‐frequency disturbances in pulp properties (such as mixture composition, fibre mass concentration, and suspension freeness) and are designed using semi‐empirical rules based largely on previous experience. Tests made on both laboratory and industrial‐scale pulp chests indicate that they are subject to non‐ideal flows, including channelling and creation of dead zones. In the present work, a commercial computational fluid dynamic (CFD) software (Fluent) is used to model two industrial pulp stock chests. The first chest is rectangular, agitated using a single side‐entering impeller, and feeds a mixture of chemical pulps at 3.5% mass concentration (Cm) to a papermachine. The second chest has rectangular geometry, with a mid‐feather wall used to direct suspension flow through a U‐shaped trajectory past four side‐entering impellers. This chest is used to remove latency from a Cm = 3.5% thermomechanical pulp suspension ahead of stock screening. For CFD computations, pulp rheology was described using a modified Hershel–Buckley model. Steady‐state simulations were made corresponding to process conditions during mill tests. The calculated steady‐state flows were then used to determine the dynamic response of the virtual chests and then compared with experimental measurements and found to agree reasonably well. The computed flow fields provided insight into mixing processes occurring within the chests, showing cavern formation around the impellers (which reduced the agitated volume available for mixing). Mass‐less particle tracking, using the steady‐state flow field, gave insight into the stagnant regions and bypassing zones created in the vessels. This paper discusses difficulties encountered in characterising the mixing (both experimentally and computationally) and the limitations of the industrial data. 相似文献
82.
A. Bhattacharya P. Ray H. Brahmbhatt K. N. Vyas S. V. Joshi C. V. Devmurari J. J. Trivedi 《应用聚合物科学杂志》2006,102(4):3575-3579
Pressure driven techniques (viz. reverse osmosis and nanofiltration) have the potentiality to remove the pesticides from water. The observations revealed that pesticides removal mostly depends upon the molecular weight (size exclusion) and hydrophobicity (log P) of the pesticides. Interfacial polymerization of m‐phenylene diamine (MPD) and trimesoyl chloride (TMC) on the polysulfone membranes impart the salt rejection property in it. It is shown that with the greater salt rejection property, the performance removal of pesticides also is in increasing trend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3575–3579, 2006 相似文献
83.
A multispeed testing method for obtaining tool-life parameters using radioactive tools has been developed. By suitable interpolation of the instantaneous rates of absolute wear measured for a number of discrete cutting speeds, the corresponding tool-life values can be deduced in a test employing a single cutting edge. Using failure criteria based on wear-land width, crater volume and total wear volume, tool-life parameters were obtained in orthogonal cutting tests with irradiated high speed steel tools. Subsidiary experiments, including conventional tool-life testing, confirmed the validity of the multispeed method over the cutting speed range investigated. 相似文献
84.
Jallipalli A. Kutty M.N. Balakrishnan G. Tatebayashi J. Nuntawong N. Huang S.H. Dawson L.R. Huffaker D.L. Mi Z. Bhattacharya P. 《Electronics letters》2007,43(22)
A GaSb quantum-well (QW) laser diode grown monolithically on a 5deg miscut Si (001) substrate is presented. The III-Sb epi-structure is grown monolithically on the miscut Si substrate via a thin (50 nm) AlSb nucleation layer. The 13% lattice mismatch between AlSb and Si is accommodated by a self-assembled 2D array of interfacial misfit dislocations (IMF). The 5deg miscut geometry enables simultaneous IMF formation and anti-phase domain suppression. The 1 mm times 100 mum GaSb QW laser diode operates under pulsed conditions at 77 K with a threshold current density of 2 kA/cm2 and a maximum peak power of ~20 mW. Furthermore, the device is characterised by a 9.1 Omega forward resistance and a leakage current density of 0.7 A/cm2 at -5 V. 相似文献
85.
Weld bead-in-grooves were deposited on low alloy, high strength steel plates (ASTM A 517 Grade “F”) with a commercial flux-cored
filler wire, Auto-MIG 420, at different welding conditions. Microstructure and mechanical properties of welds were characterized
by means of optical microscopy, SEM, TEM, EPMA, microhardness measurements, tensile tests, and Charpy impact tests. Hydrogen
content of weld metals in as-weld condition and after exposing in simulated service condition was measured by LECO Gas Analyzer.
Microstructure of weld metals consisted primarily of lath martensite with small amount of M-A constituents (Martensite-Austenite
alternating layers). For some particular welding conditions, such as higher heat input and lower preheat temperatures etc.,
acicular ferrite is observed with lath martensite. Welds consisting of acicular ferrite in the microstructure showed improved
mechanical properties as well as lower hydrogen absorption. The study provides guidelines for selecting proper welding conditions,
which results in lower propensity to absorb hydrogen during service, as well as better mechanical properties. Necessity of
post-weld heat treatment processes, which is mainly performed to achieve toughness, may be reduced; consequently saving cost
and time of the welding process. 相似文献
86.
A novel freeze-drying protocol has been explored to render fast and cost-effective freeze drying of hyperamylase producing Bacillus subtilis MTCC2396 employing a tungsten halogen lamp radiator (THLR) as a heat source. Response surface methodology assessed the maximum reduction in moisture content (96.07%) and minimum reduction in α-amylase (EC 3.2.1.1) activity (1.02%) in 4 h drying time at 42.5°C radiation temperature. α-amylase activity (0.046 U) and final moisture content (3.93%) of the optimally freeze-dried bacterial strain appeared satisfactory. The freeze-drying time using THLR (4 h) is remarkably lower compared to that under a conventional conductive plate heater (CPH) (10 h) at otherwise identical conditions. The higher effective moisture diffusivity of 0.0052 to 0.0078 m 2/s under THLR compared to 0.00084 to 0.0015 m 2/s under CPH (corresponding to 20–50°C) advocated the superiority of the THLR heating protocol. The higher efficacy of THLR was also evidenced through lower activation energy (8.42 kJ/mol) of moisture diffusion compared to that (12.051 kJ/mol) of CPH. The optimally freeze-dried bacteria demonstrated the same growth rate in addition to exhibiting excellent retention of bioremedial (Hg2+ removal) activity to that of the control. 相似文献
87.
Maitreyee Bhattacharya 《Metallurgical and Materials Transactions B》2011,42(2):380-384
The synthesis of magnetic Ni nanoparticles is being investigated by the reduction of NiO nanoparticles in the presence of
hydrogen gas. In this study, nanocrystalline NiO particles have been synthesized by a homogenous carbonate precipitation method
employing nickel electrolyte (NiSO4) as the source of nickel and ammonium hydrogen carbonate as the precipitating agent. Nickel electrolyte (NiSO4) was obtained after processing of sea nodules by the roasting-ammonia leaching-solvent extraction method. The physicochemical
characterization of NiO and Ni particles, i.e., bright field image by transmission electron microscope, X-ray diffraction, scanning electron microscope, energy dispersive
X-ray analysis, Fourier transform-infrared (FT-IR) study, and magnetic measurements by vibration sample magnetometer (VSM)
are studied. The particles are observed to be superparamagnetic. 相似文献
88.
Manjima Bhattacharya Riya Chakraborty Arjun Dey Ashok Kumar Mandal Anoop Kumar Mukhopadhyay 《Ceramics International》2013,39(2):999-1009
The present experiments were focused on nanoindentation behaviour and the attendant “micro-pop-in” in a dense (~95% of theoretical) coarse-grain (~20 μm) alumina ceramic as a function of loading rate variations at three constant peak loads in the range of 105–106 μN. Based on the experimental results here we report for the first time, to the best of our knowledge, an increase in intrinsic nano scale contact resistance as well as the nanohardness with the loading rate. These observations were explained in terms of the correlation between the nanoscale plasticity and shear stress active just underneath the nanoindenter. 相似文献
89.
The problem of designing offshore manufacturing contract resulting in optimal transfer price is troubling multinational companies over the past few years. This paper proposes designing offshore manufacturing contracts based on the transfer price in the form of bilevel programming problems after considering green tax. In these contract designs, a firm in a developed country sells a single product in its market. The same product is simultaneously being manufactured by another firm in a developing country with lower manufacturing cost. After anticipating the consumer demand, the seller places an order, based on which the manufacturer manufactures the ordered quantity, and offers a transfer price which in turn maximises its net profit after paying green tax to its government. While setting the transfer price, the manufacturer considers the manufacturing cost, the export duty payable to its government and the cost of shipping the product to the developed country. After buying the product from the manufacturer at the transfer price, the seller then sets the retail price which maximises its net profit after paying the import duty to its government; the retail price, however, must not be more than the maximum retail price applicable to the market. Thus, offshore manufacturing contract results in optimal after-tax profits for both the firms. An experimental study has been carried out to discuss the practical aspects of the results developed, where a US firm is offshoring its manufacturing activity to a Chinese firm in order to draw maximum profit. 相似文献
90.
Ranjan Bhattacharya Susmita Bandyopadhyay 《The International Journal of Advanced Manufacturing Technology》2010,51(1-4):397-414
This paper focuses on the facility location problem with two conflicting objectives. We observe that minimization of the total cost of a particular echelon may lead to the increase in the total cost of a supply chain as a whole. Thus, these conflicting objectives are required to be met together from a supply chain perspective. We have solved the problem formulated in mixed nonlinear programming by a multi-objective evolutionary algorithm (MOEA) known as non-dominated sorting algorithm, or NSGA II in short. Numerical example is provided to show the effect of the algorithm on the solution. 相似文献