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Transaction on Civil Engineering

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Transaction on Civil Engineering
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Transaction on Civil Engineering
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Transaction on Civil Engineering
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Transaction on Civil Engineering
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Transaction on Civil Engineering
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Transaction on Civil Engineering
 
Transaction on Mechanical Engineering

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Transaction on Mechanical Engineering
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Transaction on Mechanical Engineering
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Transaction on Mechanical Engineering
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Transaction on Mechanical Engineering
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Transaction on Mechanical Engineering
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Transaction on Mechanical Engineering
 
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Transactions on Chemistry and Chemical Engineering
 
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Transaction on Computer Science & Engineering and Electrical Engineering
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Volume 17, Issue 4, 2010
Transaction on Mechanical Engineering


Gauss Integration Singular Integrals of BEM for Geometrically Linear ElementsLimits in Nearly
 
        M. Abbaspour (Professor)
  • M. Ghodsi [PhD.]

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The most suitable and widely used numerical integration method for boundary integrals in the BEM method is Gauss-Legendre integration. But, this integration method is not appropriate for singular and nearly singular integrations in BEM. In this study, some criteria are introduced for recognizing nearly singular integrals in the integral form of the Laplace equation. At the rst stage, a criterion is obtained for the constant element and, at the later stages, higher order elements are investigated. In the present research, the Romberg integration method is used for nearly singular integrals. The results of this numerical method have good agreement with analytical integration. The singular integrals are solved by composing the Romberg method and midpoint rule. Constant, linear and other interpolation functions of potentials over an element are a category of BEM elements. In those elements, the Gauss-Legendre integration will be accurate if the source point is placed out of the circle with a diameter equal to element length, and its center matched to the midpoint of the element.

Keywords:
Boundary element method

    Gauss-Legendre integration
      Laplace equation
        Nearly singular integrals
          Romberg integration


Comparison of the Mollification Method, Wavelet Transform and Moving Average Filter for Reduction of Measurement Noise Effects in Inverse Heat Conduction Problems
 
        S. D. Farahani (MSc.)
  • F. Kowsary [PhD.]

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This paper proposes a procedure to smooth temperature data by wavelet transform, moving average filter and the mollification method prior to utilizing the IHCP methods (i.e. the conjugate gradient method, the Tikhonov regularization method) for unknown heat ux estimation. The measured transient temperature data utilized in the solution may be obtained from locations inside the body or from locations on its inactive boundaries. Two case studies are used to investigate the eciency and accuracy of the mentioned procedure. The first case study is performed on a rectangular body. The second case study demonstrates the ability of the proposed method to estimate heat ux in a more complicated geometry. Smoothing measured data causes an increase in the accuracy and stability of the estimation.

Keywords:
Mollification method

    Wavelet transform
      Moving average filter
        Estimated heat ux; Conjugate gradient method
          Tikhonov regularization method.


Experimental Investigation of Bae E ect on the Flow in a Rectangular Primary Sedimentation Tank
 
        B. Firoozabadi (PhD.)
  • H. Jamshidnia [MSc.]

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In primary sedimentation tanks, short-circuiting enlargement of dead zones and high ow mixing problems are caused by circulation regions (dead zones), which can reduce the optimal sedimentation of particles. For proper design of such tanks, the formation of recirculation zones should be avoided. The provision of a bae as a geometrical modi cation of a tank may in uence the ow eld for better sedimentation. Thus, in this study, velocity measurements were performed by a three-dimensional Acoustic Doppler Velocimeter (ADV) to investigate bae e ects on the velocity distribution in a primary rectangular sedimentation tank, quantitatively. E ects of bae positioning were also determined. Mean ow analysis shows how a bae can alter the hydrodynamics of the ow eld. It was quantitatively found that the intermediate bae not only in uences the ow eld in its downstream, but also a ects the ow pattern in its upstream. It was found that the bae setting and its position relative to the inlet and outlet in uences the ow eld and the development of ow. Baed ow may provide better conditions for sedimentation by in uencing velocity pro les. However, further detailed experimental study is necessary to fully capture the bae e ect and obtain further insight into the complex ow eld in a sedimentation tank.

Keywords:
ADV

    Intermediate bae
      Sedimentation tank
        Primary settling tank
          Reverse ow region.


Classification of Mean Arterial Pressure Regimes in ICU Using a Model-Based Support Vector Machine: Acute Hypotensive, Critical and Survival Episodes
 
        M.R. Homaeinezhad (PhD.)
  • A. Ghaffari [Professor]
  • M. Akraminia [MSc.]
  • M. Atarod [MSc.]
  • R. Rahmani [PhD.]

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In this study, a new pattern discrimination method for the classi cation of Mean Arterial Pressure (MAP) regimes in ICU via an appropriately regulated Radial Basis Function (RBF) Support Vector Machine (SVM) is described. The aim of this classi cation is to detect hazardous cardiogenic shock situations to prevent probable fatal failure of organs. To this end, rst, electrocardiogram (ECG) and Blood Pressure (BP) waveforms are processed via a Modi ed Hilbert Transform (MHT), and QRS complexes (equivalently obtaining heart rate-HR trend) and pressure pulses (equivalently obtaining trends of systolic, diastolic and mean arterial pressures) are detected, respectively. In the next step, a RBFSVM classi er is tuned using features obtained from the cardiogenic shock risk scoring model developed by Hasdai et al. (2000) to classify MAP regimes into three categories

    survival (the status that will not fall into shock), critical (the transient status that may lead to shock or a return to the survival episode) and Acute Hypotensive Episode -AHE (meaning cardiogenic shock will certainly occur.) Then, the regulated RBF-SVM classi er is applied to 60 records of the Computers in Cardiology (CinC) Challenge 2009 and the values of Se = 92% and P+ = 93% are obtained for sensitivity and positive predictivity, respectively. As some results of this study, the proposed classi cation method recognized truly 15 subjects out of 15 normal (without shock episodes) subjects of the MIMICII database as belonging to the \survival class", while the algorithm could classify 24 subjects as \AHE", 3 subjects as of the \critical class" and 3 subjects as in the \survival" situation out of 30 shock containing records of the MIMICII database.

    Keywords:
    Acute hypotensive episode
      Cardiogenic shock
        Blood pressure pulse detection
          Piecewise polynomial tting
            Support vector machine
              Risk scoring model.


Optimal Trajectory Planning with the Dynamic Load Carrying Capacity of a Flexible Cable-Suspended Manipulator
 
        M. H. Korayem (Professor)
  • E. Davarzani [MSc.]
  • M. Bamdad [MSc.]

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This paper presents an indirect method for computing optimal trajectory, subject to robot dynamics, exibilities and actuator constraints. One key-issue that arises from mechanism exibility is nding the Dynamic Load Carrying Capacity (DLCC). The motion planning problem is rst formulated as an optimization problem, and then solved using Pontryagin's minimum principle. The basic problem is converted to the Two-Point Boundary Value Problem (TPBVP), which includes joint exibility. Some examples are employed to compare three models, dynamic, exible joint, and rigid. The results illustrate the e ectiveness of this indirect method.

Keywords:
Path planning

    Payload
      Flexible cable-suspended manipulator
        Optimal control
          Two point boundary value problem


Surface Characterization of Through Cage Plasma Nitriding on the Surface Properties of Low Alloy Steel
 
        F. Taherkhani (MSc.)
  • A. Taherkhani [MSc.]

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DIN 1.6580 low alloy steel has been plasma nitrided using the novel Through Cage (TC) plasma nitriding technique. Experimental results show that the thickness of the compound layer increases with temperature, as well as nitrogen percent, in the gas mixture, that an increase in screen hole size has no e ect on the compound layer thickness under screen top lid conditions and, also, that an increase in screen hole size at the same temperature results in an increase in the thickness of the compound layer under iron plate top lid conditions. The results of micro-hardness measurements indicate that surface hardness increases with temperature, as well as nitrogen volume, in the treatment gas. It was also found that the hardness values obtained using a screen top lid are relatively greater than those obtained using an iron plate top lid.

Keywords:
Plasma nitriding

    Through Cage Plasma Nitriding (TCPN)
      Active screen
        Compound layer; Low alloy steels.