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  Journal of Mechanics Engineering and Automation

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Volume 1, Number 3, August 2011
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Abstract: Discovery of effect of force adaptation in mechanics is presented. The discovery is based on use of the mobile closed mechanical contour for force transfer from the mechanism input link to an output link. According to discovery the motion transfer can be carried out by Assur structural group in the form of the mobile closed contour, and the output link is the link with one degree of freedom. The received mechanical system includes an input link, an output link and the closed contour placed between them as fourth class Assur structural group. The kinematic chain has two degrees of freedom. However the closed contour imposes an additional constraint on relative motion of its links. The carried out discovery allows providing the variable transfer ratio only due to the variable external load. Mechanical properties of the closed contour allow providing the required transfer ratio independently, smart and automatically.

Key words: Force adaptation, closed contour, constraint.



Application Study on Synthesis Method of Earthquake Motion

Kahori Iiyama, Fumio Sasaki, Masahiko Nakamura, Akira Tanabe, Tetsuo Tamaoki, Wataru Mizumachi and Michio Yamada



Abstract: For seismic design of structure and machinery, it is important to reproduce input earthquake motions that are likely to occur at a target site. Among the various methods used for generating artificial earthquake motions, the Synthesis Method of Trigonometric Function is used widely. In this method, artificial waves are reproduced by superimposing sine waves and then adding information about amplitude and phase in the frequency domain. In the Japanese architectural design code, the amplitude is standardized as the target response spectrum, and the phase can be defined by random numbers or by the phase of one observed wave. However, a random phase is distinctly different from the phase of an actual earthquake. Further, the phase of one observed wave is confined to the phase characteristic of the artificial wave of only one specific earthquake motion. In this paper, the authors introduce a new convenient method to reproduce artificial waves that not only satisfy the standardized spectrum property but also have the time-frequency characteristics of multiple observed waves. The authors show the feature of the artificial waves, discuss the merits of the method by comparing with existing methods, and report the tendencies of the non-linear response by using simple model.

Key words: Artificial earthquake motion, wavelet transform, time-frequency characteristics, non-stationarity.


Laser Processing Mechanism of Monocrystalline Diamond

Etsuji Ohmura, Katsuko Harano, Kenichi Watatani and Keiji Ebata



Abstract: When a Nd:YAG laser, the wavelength of which is permeable for diamond, is focused on the surface of a diamond sample, a layer of surface material is ablated. Therefore, diamond can be cut by repetitive irradiation. In this study, the processing mechanism of ablation for a single crystal diamond was examined using a heat conduction analysis, considering laser absorption at the surface or the temperature dependence of absorption coefficient. When the laser beam is absorbed at the surface layer, the surface layer is ablated during an early period in the laser pulse. Once the absorption surface layer is ablated, the laser beam penetrates the base material and ablation stops. On the other hand, if the authors assume that single crystal diamond has the temperature dependence of absorption coefficient which is about equal to that of CVD (chemical vapor deposition) diamond, the temperature rise is not enough to ablate the material. However, it became clear that the diamond is ablated deeply when the authors consider both absorption at the surface layer and the temperature dependence of the absorption coefficient. It can be considered that the surface is transformed to graphite and becomes the absorption layer during the repetitive irradiation. It is estimated that the phase change to graphite is very small and its volume fraction is a few percent at most.

Key words: Laser ablation, laser cutting, single crystal diamond, absorption layer, absorption coefficient, heat conduction analysis.



Abstract: A two-dimensional stress analysis was developed to evaluate the failure of composite joints using characteristic length method. In this study, the accuracy of characteristic length method on the prediction of failure strength and failure mode using different failure criteria was investigated. The stresses required for evaluating the joints were computed from stress functions obtained from displacement expressions that satisfy boundary conditions of the hole. The available experimental data for joint strength in literature were compared with the predicted failure loads and modes of failure for different composite pinned joints. No single failure criterion utilized to evaluate the failure gave a universally best fit across the three joints evaluated. However, the accuracy of characterizing the joints failure varies with joint laminate and choice of failure criterions.

Key words: Failure criterions, characteristic length, evaluate and joint strength.


Optimization of the Tracking Mechanism for a PV String

Irina-Nicoleta Tatu and Cătălin Alexandru



Abstract: The paper presents researches on increasing the energetic & economic efficiency of the photovoltaic (PV) conversion by designing and optimizing a dual-axis tracking mechanism that simultaneously changes the position of the modules using two motor sources. The driving source for the daily motion is a rotary motor, while the elevation motion is performed with a linear actuator. The main task in optimizing the tracking mechanism is to maximize the energetic gain by increasing the solar input and minimizing the energy consumption for tracking. The design strategy aims to identify the optimum angular field for the daily motion, as well as the optimum actuating time in the step-by-step motion. The study is made by developing the virtual prototype of the tracking mechanism, in the mechatronic concept. The virtual prototyping platform includes the following software solutions: CATIA (Computer Aided Tri-Dimensional Interface Application)¡ªto create the solid model, which contains information about the mass & inertia properties of the parts, ADAMS (Automatic Dynamic Analysis of Mechanical Systems)/View¡ªto model the mechanical structure of the solar tracker, and EASY5 & ADAMS/Controls-for the control system design.

Key words: PV (photovoltaic) string, tracking mechanism, control system, virtual prototype, optimization.



Abstract: The article presents the path planning algorithm to be applied in the Chinese chess game, and uses multiple mobile robots to present the experimental scenario. Users play the Chinese chess game using the mouse on the supervised computer. The supervised computer programs the motion paths using A* searching algorithm, and controls mobile robots moving on the grid based chessboard platform via wireless radio frequency (RF) interface. The A* searching algorithm solves shortest path problems of mobile robots from the start point to the target point, and avoids the obstacles on the chessboard platform. The supervised computer calculates the total time to play the game, and computes the residual time to play chess in the step for each player. The simulation results can find out the shortest motion paths of the mobile robots (chesses) moving to target points from start points in the monitor, and decides the motion path to be existence or not. The eaten chess can moves to the assigned position, and uses the A* searching algorithm to program the motion path, too. Finally, the authors implement the simulation results on the chessboard platform using mobile robots. Users can play the Chinese chess game on the supervised computer according to the Chinese chess game rule, and play each step of the game in the assigned time. The supervised computer can suggests which player don¡¯t obey the rules of the game, and decides which player to be a winner. The scenario of the Chinese chess game feedback to the user interface using the image system.

Key words: Path planning, Chinese chess game, multiple mobile robots, A* searching algorithm, wireless RF (radio frequency) interface.



Abstract: This paper is on control system design for visual based indoor inspection by the model helicopters. For the indoor inspection system for large structures, there are some cases where it is difficult for humans to work with. This paper introduces indoor inspection helicopter system with only inspection camera and prism for position sensing as payload. The control system is designed to help the operator of the inspection system to control the helicopter to designated position without much practice. The cases of the control by experienced and novice operators are compared and results show that the system has feasibility for indoor inspection system to be used by any kind of users.

Key words: Indoor inspection system, visual feedback, man in the loop system, control system design.



Abstract: The integration between engineering and knowledge systems (KS) in a manufacturing environment in a network of industrial enterprises was investigated. The drivers for this application of engineering design to infrastructure in an industrial setting where cost and time to market are vital were to spread best practice, and to gain experience in dealing with the regulatory authorities according to ISO 14000. Therefore, the aim of this study was to evaluate the performance of the industrial wastewater treatment plant of the Hilla Textile Factories, to find an appropriate method of treating the industrial wastewater so as to render it fit for reuse or safe to be disposed of as stipulated by the Iraqi laws on effluent disposal. The removal efficiencies of the different parameters used to describe water quality was low. It was found that the removal efficiency of COD (Chemical Oxygen Demand) was 20-21%, that of BOD (Biochemical Oxygen Demand) was 17-30% and that of TSS (Total Suspended Solids) was 27-31%. The quality of the effluent was not in line with those of either the Iraqi or American standards.

Key words: Source of water, knowledge systems, water quality, water pollution, activated carbon adsorption, granular activated carbon.


Study of Comparative Saturated Sliding Mode Control and LQR Controller

Borhen Torchani, Anis Sellami, Radhi M¡¯hiri and Germain Garcia



Abstract: The saturation problem is the one of the most common handicaps for applying to real applications, especially the actuator saturation. This paper focuses on the robustness of the sliding mode control (SMC) which incorporates a saturation constraint technique compared to classical linear quadratic regulator (LQR) with saturation. In the first step, the authors present a design methodology of SMC of a class of linear saturated systems. The authors present the structure of the saturation, after that the synthesis of the sliding surface is formulate as a problem of root clustering, which leads to the development of a continuous and non-linear control law that ensures the reaching condition of the sliding mode. The second step is devoted to present briefly the LQR controller technique. Finally, to validate results, the authors demonstrate an example of a quarter of vehicle system.

Key words: Variable structure control, sliding mode control, robustness, LQR (linear quadratic regulator), saturation.




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