Transactions of the Canadian Society for Mechanical Engineering
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Volume 36 (2012), Issue 2
Explosive welding of unequal surface using groove method
Mohammad Tabatabaee Ghomi, Jafar Mahmoudi, Abolfazl Khalkhali, Gholamhossein Liaghat
Bond strength of welded joints is an important factor in the explosive welding process. In such welding process, stress waves produced by explosive energy propagate at the free surface and produce tension stresses. These waves result in spalling and scabbing at the edges of metals and reduce the tensile bond strength of explosive welding. The most common method for solving this problem is cutting and sizing the edges. However, this is not possible when the two metal parts to be joined are of unequal surfaces (a small plate to a large plate). This paper focuses on applying a new technique (Groove Method) for solving the strength problem at the edges for obtaining uniform welding. In this way, experimental and numerical analyses are performed to evaluate the Groove Method. The obtained results show the success and effectiveness of the groove method suggested in this paper.
Développement d’un modèle semi-empirique pour la prédiction de la cohérence d’un jet utilisé dans les procédés de rectification
Benoit St-Pierre, Jean-François Chatelain, Louis Dufresne
La productivité des procédés de rectification par dressage continu (Continuous Dress Creep Feed - CDCF) est principalement limitée par les marques de brûlure générées sur les surfaces usinées lorsque des paramètres de coupe trop agressifs sont utilisés. Ce problème peut être résolu en améliorant l’application du fluide de refroidissement dans la zone rectifiée en utilisant des buses à jet cohérent. Afin d’étudier l’influence des paramètres de conception d’une buse sur la cohérence du jet de refroidissement tout en diminuant les coûts et le temps associé à une approche expérimentale, le présent travail illustre comment élaborer un modèle semi-empirique qui permet de prédire la cohérence physique d’un jet de fluide de refroidissement à base d’eau produit par une buse de type Webster en utilisant principalement des résultats de dynamique des fluides numérique (CFD). Un minimum de résultats expérimentaux est requis pour définir ce modèle qui utilise l’ouverture des profils de vitesse numérique pour faire sa prédiction. Nos résultats ont montré que le modèle semi-empirique développé, en utilisant notre approche, permet de prédire la cohérence d’un jet de fluide de refroidissement avec moins de 4% d’erreur.
Calculation and application of hourly emission factors for increased accuracy in scope two emission calculations
Kurt Frommann, Evan DiValentino
The accepted method of calculating GHG emissions from the consumption of grid-purchased electricity, otherwise known as scope two emissions, is limited to one emission factor that represents an annual average. The emission intensities of large-scale electrical grids change by the hour, therefore requiring hourly precision in emission calculations for optimal accuracy. For the power market of Ontario, Christian Gordon and Alan Fung of Ryerson University have developed a method of generating hourly emission factors to better measure the impact of renewable technologies. Although calculations using this method demonstrate improvement from the e-grid average, results can be further improved through the use of facility-specific emission factors and consistent units of measurement. This paper recommends a modified methodology that yields more accurate hourly emission calculations and provides opportunity in quantifying scope two emissions with a high degree of precision.
Synthesis of Watt-I path generators with coupler points passing through three or four acceleration poles
Wen-Miin Hwang, Jing-Ren Wang
This article presents a synthesis technique for the planar Watt-I six-bar mechanism with a coupler point passing through three or four acceleration poles. The parametric equations for the loci of the acceleration pole on the fixed link and the coupler plane of the Watt-I mechanism driven by a crank with a constant rotational speed are derived. The desired coupler point of a path generator passing through three or four acceleration poles should be a triple or quadruple point on the locus of the acceleration pole described on the coupler plane. Using the parametric equations and multiple points on the locus of the acceleration pole on the coupler plane, the procedure for synthesizing the Watt-I path generator with a coupler point passing through three or four specified acceleration poles that accord with the specified crank angles is proposed. Two examples are provided to illustrate the feasibility of the proposed method.
Ground-purity inspection for a group of robotic cleaners
Min-Chie Chiu, Long-Jyi Yeh, Tian-Syung Lan, Wei-Cheng Liao, Chiu-Hung Chung
The main purpose of this paper is to create a mechanism that can automatically inspect ground cleanliness of a group of mobile cleaning robots. A single-chip Microcontroller PIC18F4520 is used as a control core in the robot. The robot driven by two DC motors is equipped with two ultrasonic-ray-distance-detectors to calibrate the robot’s movement via the detected angle between the wall and the robot. In addition, a vertical movement mechanism used to lift and put down the sample-gathering device is actuated via a motor-driven cam system. Moreover, a sample specimen of the ground impurity gathered by white gummed tape will be scrolled by a motor to a specified position for further photographic processing. The captured image will then be transmitted back to the remote pc –the master pc– for image analysis and cleanliness classification via a wireless network and a series port transmission protocol. Consequently, experimental results reveal that robot-inspected ground-cleanliness using image.
The smooth particle variable structure filter
S. Andrew Gadsden, Saeid R. Habibi, Thia Kirubarajan
In this paper, a new state and parameter estimation method is introduced based on the particle filter (PF) and the smooth variable structure filter (SVSF). The PF is a popular estimation method, which makes use of distributed point masses to form an approximation of the probability distribution function (PDF). The SVSF is a relatively new estimation strategy based on sliding mode concepts, formulated in a predictorcorrector format. It has been shown to be very robust to modeling errors and uncertainties. The combined method, referred to as the smooth particle variable structure filter (SPVSF), utilizes the estimates and state error covariance of the SVSF to formulate the proposal distribution which generates the particles used by the PF. The SPVSF method is applied on two computer experiments, namely a nonlinear target tracking scenario and estimation of electrohydrostatic actuator parameters. The results are compared with other popular Kalman-based estimation methods.
Optimum layouts for wire-actuated parallel manipulators considering their stiffness characteristics and wire failure
Leila Notash, Amir Moradi
In this paper, stiffness of planar translational wire-actuated parallel manipulators is studied. The complete form of the stiffness matrix of the two degrees of freedom manipulators is formulated parametrically. The differential form of the static force balance equations is used to incorporate the variation of wire stiffness with wire length and the change in the Jacobian matrix under external force in the stiffness model. Failure of a wire, for the cases that the wire is disconnected or slack, as well as reconfiguring the anchor positions are investigated and their effects on the workspace of manipulators are presented while satisfying the constraints on wire tension and minimum stiffness. The stiffness characteristics of an example manipulator, before and after a wire failure, are discussed. Optimum layouts of the manipulator, by reconfiguring the positions of wire anchors, are identified to maximize the area of the stiffness maps.
Full journal title: Transactions of the Canadian Society for Mechanical Engineering
Abreviated journal title: Trans. Can. Soc. Mech. Eng.
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