ENGINEERING NEWS IN BRIEF

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                  ENGINEERING NEWS IN BRIEF
                        E-Mail Newsletter

                               No.68
             Issued by the Asian TOP Panel, August 2007

           The Chinese Mechanical Engineering Society (CMES)
           The Institution of Engineers, Indonesia (PII)
           The Japan Society of Mechanical Engineers (JSME)
           The Korean Society of Mechanical Engineers (KSME)

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    According to the agreement made in the 2nd Asian TOP Panel Meeting,
the ENGINEERING NEWS IN BRIEF (E-mail newsletter) has now been edited
by the CMES for the year 2007.

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[Contents]

(1) Velocity Calculation and Analysis of In-Pipe Robot Power Self-Supported by Fluid      (Source: CMES)
(2) Vibration Model in Milling of Thin-walled Components (Source: CMES)
(3) Properties of Al-Si-Y Coating Prepared by Vacuum Arc Plating for Turbine Blades of     Aero Engine (Source: CMES)
(4) Generation and Reduction of Electromagnetic Excitation Force in Motors (Source:     JSME)
(5) A Regional Project for Development of Natural Cold Energy -"Snow mountain paean"     sung in a town- (Source: JSME)
(6) Stress/Strain characterization of MEMS by using of confocal laser scanning     microscope with a Raman spectroscopy interface (Source: JSME)
(7) Development of Pressure Sensitive Molecular Film by Langmuir-Blodgett method
    (Source: JSME)
(8) A Study on the Nonlinearity of Chaotic Signal by Bispectral Analysis (Source: KSME)
(9) Shapes and Thermomechanical Analyses of a Hot Roll for Manufacturing Electrodes of     Polymer Batteries (Source: KSME)
(10) Experimental Study on the Heating Performance of a Variable Speed CO? Heat Pump     with a Variation of Operating Conditions (Source: KSME)

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(1)Velocity Calculation and Analysis of In-Pipe Robot Power Self-Supported by Fluid

   LI Duanneng YUAN Jiangnan YANG Yimin
   (Faculty Electromechanical Engineering, Guangdong University of Technology,     Guangzhou 510090)

A power self-support in-pipe robot is studied. The robot is entirely immersed in the pipe that is full of fluid. Depending on driving force generated by the pressure of fluid and energy of fluid speed, the robot moves forward with the fluid in the pipe. According to the different fluid medium, the robot must conquer inertia mass, overcome the friction force between pipe-walls, and keep proper working speed state. So the design of broad sense physical dimension and hydromechanics condition that the pipe must provide with are studied.

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(2)Vibration Model in Milling of Thin-walled Components

    WANG Tongyue HE Ning LI Liang
    College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics     and Astronautics

The Kirchhoff's vibration theory of cantilevered thin-walled beam is applied to the milling of thin-walled components and is considered to agree with the principle of small deflection vibration. Based on the milling tests, the chatter model of end milling of thin-walled components is built and the differential equation of chatter is derived also. The chatter model is simulated according to the practical cutting conditions. The measured results are in good agreement with the simulating results. The feasibility of this assumption is demonstrated. The results can be used in analyzing and milling of the correlated thin-walled components. All these work lays a reliable foundation to the further studies on the chatter rules of thin-walled components.

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(3)Properties of Al-Si-Y Coating Prepared by Vacuum Arc Plating for Turbine Blades
    of Aero Engine

    Pan Gang, Wang Yi The Chengdu Research Institute on Aviation Engine
                   Overhauling

A new Al- Si-Y coating prepared by vacuum arc plating was introduced, and its conventional technical properties was analyzed. The results show that the Al- Si-Y alloy can be deposited on blades by vacuum arc plating, and the Al- Si-Y coating has strong binding strength, compact microstructure, good oxidation-resistance and good hot-corrosion resistance. The coating can meet the requirements of high-temperature corrosion resistance of turbine blades. This technology can be widely used in the other parts which need good high-temperature corrosion resistance.

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(4) Generation and Reduction of Electromagnetic Excitation Force in Motors

     Yoshio YOSHIKUWA, Mitsubishi Electric Corporation

It is important to reduce the noise of motors because many of them are used near to people. We investigated the generation of the electromagnetic excitation force of induction motors or DC motors with the experimental apparatus we developed which can adjust the amount of eccentricity of the rotor to the stator and can measure the voltages of commutator segments. In the experimental study, we obtained the following results : in induction motors, the frequencies of the electromagnetic excitation force are affected by the number of rotor slots and the frequency of the power supply, and their levels are proportional to the eccentricity. We propose a way of decreasing the unbalanced magnetic pull in mass production motors by designing a different number of windings which are in a symmetrical position. In DC motors, the electromagnetic excitation force is influenced by the number of segments in contact between the brush and the commutator. When these conditions are different with plural brushes, the currents in the armature coils have an asymmetrical distribution and the unbalanced magnetic pull occurs in the radial direction. We propose short circuit wires in symmetrical position that make winding current symmetrical and realizes the noise reduction.

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(5)A Regional Project for Development of Natural Cold Energy -"Snow mountain paean"     sung in a town-

     Masayoshi KOBIYAMA, Muroran Institute of Technology

The time when cannot use oil as an energy source will come without fail in the near future. Although the ground surface in the snowy country is covered with snow during half a year, it plays a role as the platform for agricultural production in our country. The use of snow, called as snow utilization, wide use in our snowy country with enormous quantity of snow. Snow utilization facilities in 100 places or more have already been served to practical use in the snowy country various places .It introduces a part of the point of the snow utilization technology development that is positively related here with the people in the region, and done.

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(6)Stress/Strain characterization of MEMS by using of confocal laser scanning     microscope with a Raman spectroscopy interface

    Makoto YAMAGUCHI, Technical Research Institute Japan Society for the
                                   promotion of machine industry
     Shigeru UENO, Technical Research Institute Japan Society for the promotion
                           of machine industry

The use of micro-electro-mechanical system (MEMS) is becoming popular in many application. To predict fracture, buckling of structure, etc., knowledge of the mechanical stress/strain properties within MEMS devices is very important because stress increase may cause dislocations, film cracking, and degradation of gate oxide quality. The experimental characterization of the mechanical stress/strain properties, either stand alone, or as a verifying tool for analytical/numerical approach, is equally important, but there are not many techniques available that are capable of measuring the stress/strain locally on surface as small as that of a typical MEMS device. Confocal laser scanning microscope(CLS) interface for micro-Raman spectroscopy system has been developed to characterize stresses with micron spatial resolution in micro-electromechanical systems, and silicon membrane of a pressure sensor was characterized by using this system. The relationship between mechanical stress and defection in a small scale MEMS is clearly demonstrated. We can obtain both stress and deflection at the same time. It has been shown that CLM with a Raman spectroscopy interface system has much to offer for investigation of mechanical stress/strain in MEMS device.

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(7)Development of Pressure Sensitive Molecular Film by Langmuir-Blodgett method

    Hideo MORI, Department of Micro-Nano Systems Engineering, Nagoya University

Nowadays pressure sensitive paint (PSP) technique for pressure measurement has been widely used, because two-dimensional pressure maps can be easily obtained with simple measurement apparatus without a large number of pressure taps. The technique is based on the quenching of luminescent molecules by oxygen molecules, and it seems suitable for analyses of micro- and nano-flows which need measurement techniques employing "molecular sensors". In this study, we fabricate a pressure sensitive molecular film (PSMF) with very small thickness based on the PSP technique and the Langmuir-Blodgett (LB) film technique. It is clarified that the PSMF composed of palladium (II) mesoporphyrin IX (PdMP) as a luminophore has comparable pressure sensitivity with conventional PSPs, even if the amount of the luminescent molecules in the PSMF layer is much smaller than that in conventional PSPs. The roughness of the surface of the PSMF layer is on the order of nanometers, while that of the conventional PSP is on the order of 0.1 micron. From the results, it is expected that the change of structures of microdevices can be minimized when the PSMF technique is applied.

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(8) A Study on the Nonlinearity of Chaotic Signal by Bispectral Analysis

     Hae-Jin Lee, Gyeong-Tae Lee, Young-Sun Park, Kyung-Joon Cha, Moon-Il Park,      Jae-Eung Oh
     Hanyang University

During thirty years, deterministic chaos has moved center stage in many areas of applied mathematics. One important stimulus for this, particularly in the early 1970s, was work on nonlinear aspects of the dynamics of plant and animal populations. There are many situations, at least to a crude first approximation, by a simple first-order difference equation. Past studies have shown that such equations, even though simple and deterministic, can exhibit a surprising array of dynamical behavior, from stable points, to a bifurcating hierarchy of stable cycles, to apparently random fluctuations. But higher-order spectral analyses of such behavior are usually not considered. Higher-order spectra of a signal contain important information that is not present in its power spectrum. So, if we find the spectral pattern and get information from it, it will be able to be used effectively in so many fields. Hence, this paper uses auto bicoherence and bicoherence residue which are sort of bispectrum. Applying these to behavior of logistic difference equation, which is typical chaotic signal, the phenomenon of phase coupling and the appearance of frequency band can be analyzed. Such information means that bispectral analysis is useful to detect nonlinearity of signal.

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(9)Shapes and Thermomechanical Analyses of a Hot Roll for Manufacturing Electrodes
    of Polymer Batteries

     Cheol Kim, Dong-Sue Jang, Seon-Jun Yu
     Kyungbuk National University

The battery electrode of a mobile phone is made of layered polymer coated on aluminum foils and the hot rolling process is applied to increase the density per volume of an electrode for a high capacity battery. The flatness of batteries surfaces should be less than 2 ?. To satisfy the required flatness, the deformation of roll surface due to bending and heating of the roll should be minimized. Complicated hot oil paths of 100 ℃ inside the roll are required for heating the polymer layers. FEA was used to calculate thermal deformations and temperatures distributions of the roller. Based on FEA, a modified surface curvature called a crown roll was suggested and this gave the area of 30% improved flatness compared with a flat roll. The flat roll satisfied the flatness of 2 in the length of 340 ㎜ and the crown roll resulted in the longer length of 460 mm. Experiments to measure the temperature distribution and thermal strain were performed and compared with FEA. There were only 6% difference between two results.

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(10)Experimental Study on the Heating Performance of a Variable Speed CO Heat Pump      with a Variation of Operating Conditions

     Design Parametric Analysis of PEM Fuel Cell and Hybrid Systems
     Honghyun Cho, Ho sung Lee, Yonghee Jang, Yongchan Kim
     Korea University

The applications of a transcritical CO cycle into water heaters show advantages over conventional systems in the respect of power consumption and heating efficiency because the CO cycle has a high compressor discharge temperature. Besides, the heating performance of the transcritical CO cycle can be improved by optimizing operating conditions. In this study, the heating performance of a variable speed CO heat pump was measured and analyzed by varying refrigerant charge amount, EEV opening, compressor frequency and outdoor temperature. As a result, the optimum normalized charge for heating was 0.226. The COPs at the compressor frequencies of 40, 50 and 60 were 2.94, 2.75 and 2.25, respectively. The heating performance of the CO cycle with charge amount was more sensitive than the cooling performance. Moreover, the heating performance was improved significantly by optimizing of compressor frequency and EEV opening.

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Editor : Tian Ruizhu
           The Dept. of Internationa Affairs
           Chinese Mechanical Engineering Society