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匹配条件: “Mazumder” ,找到相关结果约244条。
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CFD Analysis of Single and Multiphase Flow Characteristics in Elbow  [PDF]
Quamrul H. Mazumder
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.44028
Abstract: Computational fluid dynamics (CFD) analysis of single- phase and two-phase flow was performed in a 90 degree horizontal to vertical elbow with 12.7 mm inside diameter. Characteristic flow behavior was investigated at six different upstream and downstream locations of the elbow. To evaluate the effects of different phases, three different air veloci-ties and three different water velocities were used during this study. Commercial CFD code FLUENT was used to perform analysis of both single and multiphase flows. Pressure and velocity profiles at six locations showed an increase in pressure at the elbow geometry with decreasing pressure as fluid leaves from the elbow. Pressure drop behavior observed to be similar for single-phase and multiphase flows. Comparison of CFD results with available empirical models showed reasonably good agreement.
Effect of Liquid and Gas Velocities on Magnitude and Location of Maximum Erosion in U-Bend  [PDF]
Quamrul H. Mazumder
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.22003
Abstract: Solid particle erosion is a micromechanical process that is influenced by flow geometry, material of the impacting surface, impact angle, particle size and shape, particle velocity, flow condition and fluid properties. Among the various factors, particle size and velocity have been considered to be the most important parameters that cause erosion. Particle size and velocity are influenced by surrounding flow velocities and carrying fluid properties. Higher erosion rates have been observed in gas-solid flow in geometries where the flow direction changes rapidly, such as elbows, tees, valves, etc, due to local turbulence and unsteady flow behaviors. This paper presents the results of a Computational fluid dynamic (CFD) simulation of dilute gas-solid flow through a U-Bend and the dynamics behavior of entrained solid particles in the flow. The effect of liquid and gas velocities on location of erosion were investigated for 50, 100, 150, 200, 250 and 300 microns sand particles. Three different fluid velocities of 15, 30.48 and 45 m/s were used in the CFD analysis. The magnitude and location of erosion presented in the paper can be used to determine the areas susceptible to maximum erosive wear in elbows and U-bends, along with corresponding rate of metal loss in these areas.
Process evaluation and treatability study of wastewater in a textile dyeing industry
Debabrata Mazumder
International Journal of Energy and Environment , 2011,
Abstract: The process was investigated in a textile dying unit and subsequently wastewater generation profile was studied for the development of a viable treatment. The dyeing unit under the study generated a considerable volume of wastewater containing inorganic chemicals and organic reactive green dye. Chemical oxygen demand (COD) resulting from all the chemically oxidizible substances and the residual color of the dye were targeted for removal. The wastewater samples were collected from different sub-processes and then characterized for the parameters viz. pH, Total solid, Suspended solid, Dissolved solid, COD and Alkalinity. A composite wastewater sample was prepared according to the measured wastewater discharge from various unit operations and used for treatability study. In the first stage, coagulation-flocculation with alum and chemical oxidation with bleaching powder were performed separately. Subsequently, adsorption study was conducted with crushed burnt coal (C.B.C.) on the composite wastewater, initially treated with 10% bleaching powder solution. After several trials, this combination was found to be effective for a C.B.C. content of 10% under a contact period of 90 minutes, which showed 100% colour and about 95% COD removal.
Single step and multiple step forecasting in one dimensional single chirp signal using MCMC based Bayesian analysis
Satyaki Mazumder
Statistics , 2014,
Abstract: Chirp signals are frequently used in different areas of science and engineering. MCMC based Bayesian inference is done here for purpose of one step and multiple step prediction in case of one dimensional single chirp signal with i.\ i.\ d.\ error structure as well as dependent error structure with exponentially decaying covariances. We use Gibbs sampling technique and random walk MCMC to update the parameters. We perform total five simulation studies for illustration purpose. We also do some real data analysis to show how the method is working in practice.
Impacts of Land Use, Fertilizer and Manure Application on the Stream Nutrient Loadings in the Salmon River Watershed, South-Central British Columbia, Canada  [PDF]
Zhanxue Zhu, Klaas Broersma, Asit Mazumder
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.328096
Abstract: Manure and fertilizer applications can increase soil productivity and land economic values, but the controversial result can be a decline of water quality due to the increased nutrient exports from soils to the streams. The impacts of landuse, manure and fertilizer application on nutrient exports from soils to the streams were analyzed using the SWAT (Soil Water Assessment Tool) model for the Salmon River watershed in south-central British Columbia, Canada. The results showed that the animal farms had the highest rates of nutrient exports from soils to the streams and the natural forested lands had the lowest. It was estimated that the whole Salmon River watershed would export approximately 11.52 t·yr-1 of organic nitrogen (ON), 8.05 t·yr-1 of nitrate nitrogen (NO3-N), 2.30 t·yr-1 of organic phosphorus (OP) and 1.36 t·yr-1 of soluble reactive phosphorus (SRP) if the whole watershed was covered by natural vegetation without human disturbance. Current landuse changes, by converting natural vegetation lands to agriculture and animal farms and associated manure and fertilizer applications, have in-creased approximately 53.30 t·yr-1 of ON, 9.68 t·yr-1 of NO3-N, 22.69 t·y-1 of OP and 6.23 t·y-1 of SRP exports to the streams in the whole watershed. The SWAT model predicted that a daily 100 kg·ha-1 of fresh manure deposit from grazing cows during grazing season from later spring to later fall could increase 2.57 kg·ha-1·yr-1 of ON, 0.39 kg·ha-1·yr-1 of NO3-N, 2.35 kg·ha-1·yr-1 of OP and 0.48 kg·ha-1·yr-1 of SRP export to the streams. Fertilization could increase 1.57 kg ha-1 yr-1 of ON and 4.02 kg·ha-1·yr-1 of NO3-N export to the streams if 100 kg·ha-1·yr-1 of nitrogen (NH4NO3) fertilizer was applied in spring. Also fertilization could increase 1.18 kg·ha-1·yr-1 of OP and 0.20 kg·ha-1·yr-1 of SRP export to the streams if 100 kg·ha-1 phosphorus (P2O5) fertilizer was applied in spring.
CFD Analysis of the Effect of Elbow Radius on Pressure Drop in Multiphase Flow
Quamrul H. Mazumder
Modelling and Simulation in Engineering , 2012, DOI: 10.1155/2012/125405
Abstract: Computational fluid dynamics (CFD) analysis was performed in four different 90 degree elbows with air-water two-phase flows. The inside diameters of the elbows were 6.35?mm and 12.7?mm with radius to diameter ratios ( ) of 1.5 to 3. The pressure drops at two different upstream and downstream locations were investigated using empirical, experimental, and computational methods. The combination of three different air velocities, ranging from 15.24 to 45.72?m/sec, and nine different water velocities, in the range of 0.1–10.0?m/s, was used in this study. CFD analysis was performed using the mixture model and a commercial code, FLUENT. The comparison of CFD predictions with experimental data and empirical model outputs showed good agreement. 1. Introduction and Background In most industrial processes, fluids are used as a medium for material transport. A complete knowledge of the principles that rule the phenomena involving fluids transportation leads to more efficient and secure systems. However, in many industries, such as petroleum, chemical, oil, and gas industries, two-phase or multiphase flow is frequently observed [1]. Multiphase flow is defined as the simultaneous flow of several phases, with the simplest case being a two-phase flow [2]. Compared to single-phase flow, the equations associated with two-phase flow are very complex, due to the presence of different flow patterns in gas-liquid systems [3]. A detailed discussion of two-phase flow phenomenon behavior is provided by Wallis [2]. The flow patterns observed in horizontal flow are bubble, stratified, stratified wavy, slug, and annular. In vertical flows, bubble, plug, slug (or churn), annular, and wispy-annular flow patterns are present. Several investigations have been reported to determine the friction factor and pressure drops in horizontal [4] and vertical [5] two-phase and multiphase flows [6]. The presence of the two-phase flow typically produces an undesirable higher-pressure drop in the piping components. In most industrial installations, elbows are frequently used to direct the flow and provide flexibility to the system [7]. Since these fittings are also used to install instruments that monitor the main parameters of the industrial process, it is important to have a reliable way to evaluate the pressure drop in these elbows [8]. As the fluid flows through the bend, the curvature of bend causes a centrifugal force; the centrifugal force is directed toward the outer wall of the pipe from the momentary center of the curvature. The combined presence of centrifugal force and boundary layer
Structure-Guided Comparative Analysis of Proteins: Principles, Tools, and Applications for Predicting Function
Raja Mazumder,Sona Vasudevan
PLOS Computational Biology , 2008, DOI: 10.1371/journal.pcbi.1000151
Abstract:
Prospects of β-SiC Based IMPATT Oscillator for Application in THz Communication and Growth of β-SiC p-n Junction on Ge Modified Si <100> Substrate to Realize THz IMPATTs
Moumita Mukherjee,Nilratan Mazumder
半导体学报 , 2010,
Abstract: The prospects of p+ n n+ cubic Silicon Carbide (3C-SiC/ -SiC) based IMPATT diode as a potential solid-state Terahertz source is studied for the first time through a modified generalized simulation scheme. The simulation predicts that the device is capable of generating a RF power output of 63.0 W at 0.33 THz with an efficiency of 13%. The effects of parasitic series resistance on the device performance and exploitable RF power level are further simulated. The studies clearly establish the potential of 3C-SiC as a base semiconductor material for high-power THz IMPATT device. Based on the simulation results an attempt has been made to fabricate β- SiC based IMPATT devices in THz region. Single crystalline, epitaxial 3C-SiC films are deposited on silicon (Si) <100> substrates by Rapid Thermal Chemical Vapour Deposition (RTPCVD) at a temperature as low as 800 0C using a single precursor methylsilane, which contains Si and C atoms in the same molecule. No initial surface carbonization step is required in this method. A p-n junction with n-type doping conc. of 4 x 10^24 m-3 (which is similar to the simulated design data) has been grown successfully and the characterization of the grown 3C-SiC film is reported in this paper. It is found that the inclusion of Ge improves the crystal quality and reduces the surface roughness.
The Effect of Ultrasound on the Microhardness and Nanohardness of Laser Welds in Mild Steel
S. Venkannah,J. Mazumder
Lecture Notes in Engineering and Computer Science , 2009,
Abstract:
Changes in Laser Weld Bead Geometry with the Application of Ultrasonic Vibrations
S. Venkannah,J. Mazumder
Lecture Notes in Engineering and Computer Science , 2009,
Abstract:
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