333 research outputs found

    Effect of Variable Thermal Conductivity on Buoyant Convection in a Cavity with Internal Heat Generation

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    A numerical study has been made to analyze the effects of variable thermal conductivity on the natural convection of heat generating fluids contained in a square cavity with isothermal walls and the top and bottom perfectly insulated surfaces. The flow is assumed to be two-dimensional. Calculations are carried out by solving governing equations for different parameters. The flow pattern and the heat transfer characteristics inside the cavity are presented in the form of steady-state streamlines, isotherms and velocity profiles. The heat transfer rate is increased by an increase in the thermal conductivity parameter

    Structural Characterization and Mechanical Behavior of Al 6061 Nanostructured Matrix Reinforced with TiO2 Nanoparticles for Automotive Applications

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    The main aims of the present chapter are to: learn synthesis procedure of AA 6061‐x wt.% TiO2 nanocomposites (x = 0, 2, 4, 6, 8, 10 and 12 wt.%) by mechanical alloying (MA); investigate structural characterization of manufactured nanocomposite powders using X‐ray line profile analysis, scanning electron microscope (SEM) and transmission electron microscope (TEM); examine consolidation method and mechanical behavior in terms of sintered density, Vickers hardness and compressive stress‐strain behavior; study the improvement of ductility in nanocomposites; and simulate the mechanical behavior using ANSYS. Here, the synthesized nanocomposites via MA were consolidated using conventional uniaxial die compaction; then, the green compacts were sintered at different temperatures. TEM microstructures of as‐milled powder samples showed the matrix crystallite sizes ranging from 45 to 75 nm, which depended on the amount of reinforcement. A remarkable decrease in matrix powder particles size with the function of reinforcement was observed due to the ceramic nano TiO2 particles acted as milling agent. The sintered nanocomposites yielded maximum strength of 1.126 GPa. The study of trimodeled composite and its mechanical behavior revealed the possibility of achieving improvements in ductility and toughness for nanocomposites. The simulated mechanical behavior results using finite element method were good agreement with experimental results

    Effect of aspect ratio on convection in a porous enclosure with partially active thermal walls

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    AbstractThe aim of the present numerical investigation is to understand the effect of aspect ratio and partially thermally active zones on convective flow and heat transfer in a rectangular porous enclosure. Five different heating and cooling zones are considered along the vertical walls while the remaining portions of the sidewalls and top and bottom of the enclosure are adiabatic. The Brinkman–Forchheimer extended Darcy model is used in the study. The governing equations are solved by the finite volume method with the SIMPLE algorithm. The computations are carried out for a wide range of parameters and the results are presented graphically. The results reveal that the location of heating and cooling zones has a significant influence on the flow pattern and the corresponding heat transfer in the enclosure. The rate of heat transfer approaches to a constant value for very low values of the Darcy number. The heat transfer rate is decreased on increasing the aspect ratio

    Performance of Diesel Engines at High Altitudes

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    Problems are encountered when conventional, normally aspirated diesel engines are operated at high altitudes. The results of a study carried out at the Indian Institute of Petroleum both on stationary and automotive diesel engines covering the principal problems of power loss and poor thermal efficiency are presented in this paper

    Lie Group Analysis of Natural Convection Heat and Mass Transfer in an Inclined Surface

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    Natural convection heat transfer fluid flow past an inclined semiinfinite surface in the presence of solute concentration is investigated by Lie group analysis. The governing partial differential equations are reduced to a system of ordinary differential equations by the translation and scaling symmetries. An exact solution is obtained for translation symmetry and numerical solutions for scaling symmetry. It is found that the velocity increases and temperature and concentration of the fluid decrease with an increase in the thermal and solutal Grashof numbers. The velocity and concentration of the fluid decrease and temperature increases with increase in the Schmidt number

    Jet: Multilevel Graph Partitioning on GPUs

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    The multilevel heuristic is the dominant strategy for high-quality sequential and parallel graph partitioning. Partition refinement is a key step of multilevel graph partitioning. In this work, we present Jet, a new parallel algorithm for partition refinement specifically designed for Graphics Processing Units (GPUs). We combine Jet with GPU-aware coarsening to develop a kk-way graph partitioner. The new partitioner achieves superior quality when compared to state-of-the-art shared memory graph partitioners on a large collection of test graphs.Comment: Submitted as a non-archival track paper for SIAM ACDA 202

    ADVANCED EMBEDDED SYSTEM ASSISTED GSM AND RFID BASED SMART SCHOOL MANAGEMENT SYSTEM

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    ABSTRACT: Among the various technological devices and systems, global system for mobile communication (GSM) is believed as an efficient and fast enough technique that can perform efficient, real time object identification and fast reporting. GSM based tracking system will pass complete information about, where the object (student) and its activities. The RFID system is utilized as a board module to attach the parts of the object (bag, identity card, tag, etc) and follow the object then and there. The designed model is studied under laboratory scale and the results are analysed. Keywords: GSM, RFID, PIC Microcontroller, Security, GSM modem. I.INTRODUCTION The risk of insecure is increasing with increasing populations, as the consequence, large magnitude of hijacks is reported. The major risk faced by the school management as well as the parental side is that the identification of the location of the pupils and their safety measures. The statistical reports perceive that most of the students are hijacked, when they are crossing the school boundary or school entrance area Advanced embedded system assisted GSM and RFID based smart school management system is used to give an access for the operation by habitual recognition of the person based upon the RFID tag information. As an example, for entrance control of an organization, the RFID tag and its reader are designed with predefined unique code of tag for individual school student. Whenever the tag is read by reader, it compares the code with the predefined codes in the machine. On the basis of correctness of the information, it sends an acknowledgement (in the form of text message) to the parents of that particular student and the same protocol is followed for all the pupils of the school. Another important feature of the system is that it maintains a record of attendance about the pupil (i.e.) "in time" "out time" which can be further transferred to the administrator via network systems. Through which we can easily compute the attendance status of the students within no time. This machine can also help to avoid human involvement in keeping the attendance record. Thus, reduction of the manpower held in the organization. This machine ensures accurate access control and record keeping. II. DESIGN AND CONSTRUCTION DETAILS A. RFID: Many types of RFID exist, but at the highest-level, we can classify RFID devices into two classes namely, active and passive tags. Active tags require power source either connected to powered infrastructure or use energy stored in an integrated battery. In the laterals, tag's lifetime is limited by stored energy, balanced against the number of read operations. As an example, an active tag is the transponder attached to an aircraft that identify the national origin. The numbers insisted in the tags represent the identification number of the candidate. The RFID utilized in the current system is given below

    Experimental Investigation on Mechanical and Turning Behavior of Al 7075/ x

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    The present research work involves the study of AA 7075-TiB2-Gr in situ composite through stir casting route. This in situ method involves formation of reinforcements within the matrix by the chemical reaction of two or more compounds which also produces some changes in the matrix material within the vicinity. Titanium Diboride (TiB2) and graphite were the reinforcement in a matrix of AA 7075 alloy. The composite was prepared with the formation of the reinforcement inside the molten matrix by adding salts of Potassium Tetrafluoroborate (KBF4) and Potassium Hexafluorotitanate (K2TiF6). The samples were taken under casted condition and the properties of the composite were tested by conducting characterization using X-ray diffraction (XRD), hardness test, flexural strength by using three-point bend test, scanning electron microscope (SEM), optical microstructure, grain size analysis, and surface roughness. It was found that good/excellent mechanical properties were obtained in AA 7075-TiB2-Gr reinforced in situ hybrid composite compared to alloy due to particulate strengthening of ceramic particles of TiB2 in the matrix. Further, Al 7075-3% TiB2-1% Gr hybrid in situ composite exhibited improved machinability over the alloy and composites due to self-lubricating property given by the Gr particles in the materials
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