======================================================================                   ENGINEERING NEWS IN BRIEF                         E-Mail Newsletter                                No.64              Issued by the Asian TOP Panel, April 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) ======================================================================     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. ====================================================================== [Contents] (1) Job Scheduling Model Of Machining System For Green Manufacturing      (Source: CMES) (2) Experimental Study On Air-Powered Engine (Source: CMES) (3) Development Of Hybrid Powertrain Control System For Parrallel-Series Hybrid      Electric Vehicle (Source: CMES) (4) Fabrication of Ultra-thin Type Infrared Fresnel lenses by Ultraprecision      Cutting of Germanium Wafers (Source: JSME) (5) Stable Operation of Optical Parametric Chirped Pulse Amplification      (Source: JSME) (6) Numerical Simulation to Enhance Technological Development of Synthesizing      Single-crystal Diamond Wafers with a Large Area (Source: JSME) (7) The Quantitative Characterization of the Dispersion State of Single-Walled      Carbon Nanotubes (Source: KSME) (8) Validation Test for Transient Hot-wire Method to Evaluate the Temperature      Dependence of Nanofluids (Source: KSME) (9) Development and Validation of Numerical Program for Predicting Electrokinetic      and Dielectrophoretic Phenomena in a Microchannel (Source: KSME) ======================================================================== (1) Job Scheduling Model Of Machining System For Green Manufacturing      HE Yan LIU Fei CAO Huajun School of Mechanical Engineering,      Chongqing University  A machining system is one of important elements for implementing green manufacturing in workshop. It has been discovered that job scheduling, which can decrease resource consumption and reduce environmental impacts, is an approach to improving green attributes of machining systems. A job scheduling model of a machining system for green manufacturing is proposed with description of the schematic model and the mathematic model, which describes the whole scheduling process and the relations of the elements of the job scheduling model. The objective architecture of the model is constructed in terms of the green attributes of machining systems which is composed of several sub-objectives, and the analysis of each sub-objective is presented. Finally, a case study is analyzed to show the application of the model. ======================================================================== (2) Experimental Study on Air-Powered Engine      ZUO Chengji QIAN Yejian School of Machinery and Automobile Engineering,      Hefei University of Technology      OUYANG Minggao YANG Fuyuan State Key Laboratory of Automotive Safety and      Energy, Tsinghua University To optimize the design of air-powered engine and enhance its performance, an extensive experimental study on engine performance of a two-stroke air-powered engine that is modified from R175 diesel engine is carried out. Two evaluating indicators are newly defined to evaluate the performance of the air-powered engine, namely specific mass flow and total energy efficiency. The lubricating experiment is carried out, three different lubricating oils, i.e. transformer oil, refrigerating oil and special oil are used. The experimental results show that the lubricating oil significantly influences the performance of the air-powered engine. When the water jacket is no water, or filled with room temperature water and hot water, the air-powered engine performance is studied. The experimental results show that the effect of heat exchange on engine performance is small and the multi-utilization of compressed air is helpful to enhance the total energy efficiency. To investigate the influence of valve timing on air-powered engine performance, three different inlet camshafts are used. The results of load characteristics and speed characteristics show that optimal performance is obtained when the inlet valve opening timing is 10 oCA before TDC. Under the condition of low engine speeds, the power performance and economy characteristic of air-powered engine are better. ======================================================================== (3) Development of Hybrid Powertrain Control System for Parrallel-Series Hybrid      Electric Vehicle      ZHOU Lei LUO Yugong YANG Diange      LI Keqiang LIAN Xiaomin State Key Laboratory of Automotive Safety and Energy,      Tsinghua University The powertrain of the parallel-series hybrid electric vehicle(PSHEV) is discussed for its features of dual-motor structure in which powers from the engine and the tractive motor are coupled at the output shaft of the transmission instead of the input shaft. Control strategies based on ICE optimal operating schedule are utilized to improve the powertrain efficiency and reduce fuel consumption. To identify the power demand of the driver, a new "nine-point-definition method" is proposed. Special attention is given to the combination control of different power sources during gear shifting. Regenerative braking is divided into the braking mode and the coasting mode and different control methods are applied for each mode. A hybrid powertrain controller (HCU) based on CAN network is developed to implement these strategies, which is proved to be able to work efficiently and stably by hardware-in-loop experiment and on-board test. Test results show that under the coordination of HCU the vehicle achieves 35% reduction in fuel consumption and improvement in acceleration performance. ======================================================================= (4)Fabrication of Ultra-thin Type Infrared Fresnel lenses by Ultraprecision     Cutting of Germanium Wafers     Jiwang YAN, Department of Nanomechanics, Tohoku University Single-crystal germanium is an excellent optical material in the infrared wavelength range. The development of germanium Fresnel lenses not only improves the optical imaging quality but also enables the miniaturization of optical systems. In the present work, we developed a ductile-mode micro grooving process for fabricating Fresnel lenses on germanium. We used a sharply-pointed diamond tool to generate the micro Fresnel structures under three-axis ultraprecision numerical control. This method enables the uniform thinning of the undeformed chip thickness to the nanometric range, thus provides complete ductile regime machining of brittle materials. Under the present conditions, a Fresnel lens which has a form error of 0.5 micron, surface roughness of 20-50 nmRy (peak-to-valley),was fabricated successfully during a single tool pass. ============================================================ (5)Stable Operation of Optical Parametric Chirped Pulse Amplification     Tetsuo HARIMOTO, University of Yamanashi A novel method for stable operation of optical parametric chirped pulse amplification (OPCPA) is described in this topic. In conventional OPCPA, the energy of a pump laser pulse is converted to that of a seed laser pulse, and an idler laser pulse occurs simultaneously due to the conservation law of energy through the interaction of pump, seed and idler laser pulses. The amplified seed laser pulse will reconvert to the pump laser pulse after the pump is completely depleted, resulting in unstable amplification and gain reduction. In our proposed OPCPA using a sequence of crystal pairs, the idler laser pulse is canceled after each crystal, and the amplified seed and residual pump laser pulses enter the next crystal so that the seed laser pulse is further amplified. Thus reconversion from the seed to pump can be avoided when the central portion of the seed laser intensity is saturated. The stability of the amplified seed laser pulse can be improved by properly controlling the crystal thickness and number. Numerical results showed that the stability of the amplified seed laser pulse is better than 1.2% for 5.0 % variation in initial intensity and duration of the seed laser pulse. The proposed scheme can be practically used as a regenerative or main amplifier in a high power laser system for laser fusion. ============================================================ (6)Numerical Simulation to Enhance Technological Development of Synthesizing     Single-crystal Diamond Wafers with a Large Area     Hideaki YAMADA, Diamond Wafer Team, Diamond Research Center,     National Institute of Advanced Industrial Science and Technology Numerical simulation has been utilized to enhance technological development of synthesizing high quality single-crystal diamond wafers with a large area. Microwave plasma chemical vapor deposition is known as the most promising method to synthesize a large and thick single-crystal diamond in a stable manner. Due to difficulty of experimental observation of plasma inside the reactor during the crystal growth, we have utilized numerical simulation from both of the macroscopic and microscopic points of view to know more efficient growth condition and to reveal growth mechanism. From the macroscopic point of view, we have simulated distributions of the power density of microwave in the plasma, temperature of the top surface of the substrate, and gas flow around the substrate. Comparing these with experimentally obtained morphology of the top surface, we have found correspondences between them. This information is instructive to design, for example,the substrate holder shapes. On the other hand, from the microscopic point of view, reactions of the radicals with the substrate surface have been analyzed. New insights have been obtained from these microscopic analyses, although it is left for future work to find a method how we can connect these microscopic insights to improvement of the actual processing condition. ============================================================ (7)The Quantitative Characterization of the Dispersion State of Single-Walled Carbon     Nanotubes     Dokyung Yoon, Jae-Boong Choi, Young-Jin Kim, Seunghyun Baik We have investigated quantitative measurement techniques of the degree of dispersion of single-walled carbon nanotubes (SWNTs). SWNTs were suspended in aqueous media using a sodium dodecyl sulfate (SDS) surfactant. SWNTs with different dispersion states were prepared by controlling the intensity and time of sonication and centrifugation. The laser spectroscopic techniques were employed to characterize the dispersion state; i.e., raman fluorescence and absorption spectroscopic techniques. Raman spectroscopy has been used to probe the dispersion and aggregation state of SWNTs in solution. Individually suspended SWNTs show increased fluorescence peaks and decreased roping peaks at a raman shift 267 Н-1 compared with the samples containing bundles of SWNTs. The ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectrum of decanted supernatant samples show sharp van Hove singularity peaks. ============================================================ (8)Validation Test for Transient Hot-wire Method to Evaluate the Temperature     Dependence of Nanofluids     Shinpyo Lee, Kyoungmin Kang One of the controversial research issues on nanofluids is the temperature dependence of the thermal conductivity of nanofluids, that is, whether it will increase or decrease according to the temperature rise. To evaluate precisely the thermal conductivity behavior of nanofluids, a systematic way of validation experiments for the measuring instrument has been highly recommended. In this paper, procedure of the validation test for transient hot-wire method using the temperature dependence of the base fluids was explained comprehensively and the comparison of the temperature dependence of water-AlO nanofluids is made between the present work and that of Das et al. ============================================================ (9)Development and Validation of Numerical Program for Predicting Electrokinetic and     Dielectrophoretic Phenomena in a Microchannel     Jae-Sung Kwon, Joo-Sung Maeng, Simon Song Electrokinesis and dielectrophoresis are important transport phenomena produced by external electric field applied to a microchannel containing a conductive fluid. We developed a CFD code to predict electrokinetic and dielectrophoretic flows in a microchannel with a uniform circular post array. Using the code, we calculated particle velocities driven by electrokinesis and dielectrophoresis, and conducted Monte Carlo simulations to visualize the particle motions. The code was validated by comparing the results with those from previous studies in literature. At a low electric field, electrokinesis and diffusion is the dominant transport mechanism. At a moderate electric field, dielectrophoresis is balanced with electrokinesis and diffusion, resulting in flowing filaments of particles in the microchannels. However, dielectrophoresis overwhelms the flow at a high electric field and traps particles locally. These results provide useful insight for optimizing design parameters of a microfluidic chip for biochemical analysis, especially for development of on-chip sample pretreatment techniques using electrokinetic and dielectrophoretic effects. ============================================================ Editor : Tian Ruizhu            The Dept. of Internationa Affairs            Chinese Mechanical Engineering Society

 

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