We present a number-density advection based method designed to calculate the condensation and evaporation of water droplets. An Eulerian-in-radius discretization scheme is adopted, making the present model suitable for use in the spectral bin model for cloud microphysics. The advection equation is solved using the constrained interpolated profile-conservative Semi-Lagrangian with rational function (CIP-CLSR) scheme. In order to evaluate the present method based on the CIP-CSLR scheme, we have performed test calculations for a sequence of condensation and evaporation using the present method and conventional methods, and then compared the results. The comparisons have revealed the advantages of the present method in terms of numerical accuracy, numerical stability, conservation and computational cost.

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Delamination cracks in a graphite/epoxy composite change the thermal expansion properties in the damaged regions. We detect this change by measuring the electrical resistance in the affected areas while heating. The proposed damage detection method is effective even when a damaged electrode is used, in contrast to the traditional method, which requires highly reliable electrodes to prevent an increase of the inherent electrical resistance. The proposed damage detection method is thus feasible for a variety of environments that might cause the degradation of the electrode. Heating of the composite is performed by Joule heating of the graphite fibers rather than general heating using an outside heat source. Graphite fibers, due to their high electrical conductivity, are used not only as the damage sensor but also as the heat source. The influences of delamination and electrode defects on a heated cross-ply beam are examined by simulation. The electrical resistance change after Joule heating is also experimentally measured. As a result, we proved that delamination detection is possible even with a damaged electrode.

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Floating roofs are widely used to prevent evaporation of the contents of large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to floating roofs due to liquid sloshing. Establishing the structural integrity of floating roofs subjected to sloshing is an urgent issue for the petrochemical and oil refining industries. The present paper proposes an axisymmetric finite element analysis for the sloshing response of floating roofs in cylindrical storage tanks. The hydrodynamic coupling of the fluid and the floating roof under seismic excitation is taken into consideration in the analysis. The fluid is assumed to be incompressible and inviscid, and the roof is assumed to be linear elastic. In addition, the sidewall and the bottom are assumed to be rigid. The theory for the finite element analysis, in which the behavior of the fluid is formulated in terms of dynamic pressure using the Eulerian approach, is proposed. The basic vibration characteristics of the floating roof, such as the natural frequencies and vibration modes, can be obtained from this analysis. These characteristics provide engineers with important information on the floating roof design.

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Floating roofs are widely used to prevent evaporation of the contents of large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to floating roofs due to liquid sloshing. Establishing the structural integrity of floating roofs subjected to sloshing is urgent issue for the petrochemical and oil refining industries. The present paper describes the sloshing characteristics of single-deck floating roofs in cylindrical storage tanks. The hydrodynamic coupling of the fluid and the floating roof is taken into consideration in the axisymmetric finite element analysis. The fluid is assumed to be incompressible and inviscid, and the roof is assumed to be linear elastic. In addition, the sidewall and the bottom are assumed to be rigid. The basic vibration characteristics of the floating roof during sloshing, such as the natural frequencies and vibration modes, are investigated. These characteristics provide engineers with important information on the floating roof design.

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Solid oxide fuel cells (SOFCs) with flat-tubular structure were successfully fabricated by ceramic wet processing. The SOFCs had three or four internal channels for fuel gas flow and were supported by the fuel electrode. The SOFCs were composed of 8 mol Y₂O₃-ZrO₂ (YSZ) electrolyte, Ni-YSZ fuel electrode, and La_0.8Sr_0.2MnO₃ air electrode. Fuel gas was uniformly supplied to fuel electrodes with fuel gas pipes made of a heat-resistant alloy. The SOFCs had an active area of 50 cm² and were operated to achieve a maximum power density of 0.23 W/cm² at 1000 °C. The effect of the fuel gas pipe on cell performance was recognized; the performance was twice as high as that of an SOFC without the fuel gas pipe. The performance of the SOFC with four channels was slightly higher than that with three channels. It also appeared that the performance of the SOFC with three channels decreased steeply with increasing fuel utilization.

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Vibration characteristics such as eigenfrequencies and eigenmodes are crucial factors that determine the dynamic performance of mechanical structures, and high performance structures that function dynamically can be designed by appropriately specifying such vibration characteristics. This paper proposes a structural optimization method for obtaining mechanical structures having specified vibration characteristics, based on the level set method. First, the basic details of a structural optimization method using the level set method, which can be applied to dynamic problems, are briefly discussed. Next, optimization problems that address the maximum eigenfrequencies, and the matching of eigenfrequencies with target values, are formulated. A new optimization algorithm based on the level set method is constructed, where a newly improved geometric re-initialization scheme is used for re-initializing the level set function, based on the zero level set surface. Using the proposed optimization algorithm, both the solving of the eigenvalue problem and the updating of the level set function are performed using the FEM, where unstructured meshes can easily be configured. Finally, several design examples are provided to confirm the usefulness of the proposed structural optimization method.

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To assist in the development and analysis of new diesel combustion systems with the features of a common-rail injection system such as multiple injections, an advanced single-cylinder optically accessible engine with a very wide observation field was developed. The combustion chamber of this engine can be viewed from the top, bottom, and side. In addition to direct observation of phenomena in the piston cavity and squish area, 2-dimensional laser diagnostics for arbitrary cross sections are also possible. This paper introduces the details of this engine. Also, the following examples of in-cylinder visualization with this engine are introduced; 1) direct observation of the soot reduction mechanism by after-injection, 2) visualization of mixture formation of pilot-injection using LIF, 3) validation of in-cylinder EGR stratification technique by LIF measurement.

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In this study, mathematical formulae for evaluating scattered components of non-compact sound are summarized, and aerodynamic noise emitted from a pantograph is predicted numerically based on the theory of vortex sound. When influence of reflection at the plane (train roof) is taken into consideration in Green's functions, interference of sound waves appears and amplitude of sound pressure at an observer located in a far field is strengthened and weakened periodically depending upon its frequency, which phenomenon is similar to the experimental results. In the low frequency range, large separations occurring at the upper and lower sides of a pantograph head, lower sides of the pantograph head support, and an upper frame are main sources of scattered sound propagating upward. In the high frequency range, sound seems to be generated by unsteady motion of small vortices shed from the pantograph head and the support. As for sound propagating sideward, release of large-scale vortices from the support and the upper frame in horizontal planes is responsible for low frequency noise, and longitudinal vortices rolling up along sides of the support seem to generate sound of high frequency.

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An axially-short expansion chamber in a duct acts as a resonator muffler. The radial size of the chamber must be altered in order to change the target frequency for noise reduction because the resonance frequency depends on the depth of the chamber. The present study reveals that the resonance frequency can be altered by changing the shape of the expansion to an ‘L’ shape, even if the radial size of the expansion is fixed. The structures of the acoustic field in the duct are obtained numerically based on a finite difference method for several L-shaped expansions. The computed results show that the resonance frequency decreases with increasing axial length of the expansion, whereas the minimum transmission coefficient is approximately constant. In addition, increasing the inlet length of the expansion enables the resonance frequency to be increased and the minimum transmission coefficient to be reduced. These results are in good agreement with previously reported experimental data.

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In the present study we attempted to develop an actuator that is comparable to a natural muscle in terms of flexibility, output force and responsiveness. In an earlier report we presented the Shape Memory Alloy (SMA) actuator protected by “a rolled film tube” that exhibited high heat resistance and high flexibility, and termed it “the unit cell”. In the present study, we developed an actuator dubbed “a motor unit” exhibiting a larger output force by bundling 7 unit cells together, and investigated the characteristics of this motor unit in experiments where the motor unit was driven by Pulse Frequency Modulation (PFM). The results of the experiments indicate that the static characteristics of the output force and the displacement due to the input pulse frequency in the motor unit are proportionate in comparison to the unit cell, and that the output force is nearly 7 times greater than that of the unit cell. Results also indicate that the time constant of the motor unit increases compared to that of the unit cell, and power conversion efficiency decreases when pulse width is extended to improve the time constant.

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It is very important to remove contaminant fully from waste PET bottles for bottle-to-bottle recycling. In this paper the mechanism to remove contaminant is proposed on the experimental degradation of waste PET bottles to the monomers by ethylene glycol. It is made up of the separation of contaminant during the degradation reaction. This model is confirmed to be correct on the recycling of deliberately contaminated PET samples using a series of surrogates based on FDA protocol. We conclude that the contaminant on waste PET bottles is fully separated from PET bottles under the proper separating condition, such as the quantity of extract, separating temperature and time.

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In recent years, fossil fuels such as petroleum, coal, and natural gas have become limited resources. In addition, bad effects caused by excessive carbon dioxide (CO₂) emissions have now begun destroying our global environment seriously. Since current living and economical standards depend strongly on fossil energy sources, it is necessary to realize a new society that utilizes biomass as a source of energy. In this background, in 2005, we manufactured a practical Stirling engine using woody biomass fuels for the first time in Japan. Further we proposed a unique co-generation system with the Stirling engine that uses woody biomass fuels such as sawdust, firewood, and wood pellets. In that co-generation system, a burner uses the woody biomass fuel to heat the air in the expansion room of the Stirling engine to about 650°C, and a water cooling system cools the air in the compression room of the engine to about 40°C. Under these operating conditions, the practical Stirling engine can generate about 3kW of electricity. In addition to the heat from the burner, which is easily recovered, the cooling water of the engine also provides useable heat. By use of simple heat exchangers, this heat can be used for domestic space heating and heating of greenhouses as well as supplying domestic hot water needs. This co-generation system utilizes up to 45% of the system-input energy in the form of electricity or heat. In this co-generation system, 43% of the input energy is wasted as heat loss from the exhaust smoke into the atmosphere. Therefore we tried to recover the waste heat by using a thermoelectric conversion module in this study. And also the performance of the Stirling cooler system using electric power based on woody biomass was tested. Due to the practical application of this combined utilization, a unique system in which both heating/cooling and power generation are available can be constructed.

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A steam control valve is used to control the steam flow from a steam generator to a turbine in power plants. The flow field in the steam control valve is usually complicated and transonic. A flow-induced vibration can occur in the valve and may cause unexpected shutdown of the plant. An experimental study is conducted to clarify the characteristics of the flow in the steam control valve. In the present study, scale effects on the condition of occurrence of various flow patterns are investigated. Experimental results show various flow patterns including new patterns which have not been reported. Additionally, even under the same operation condition, different flow patterns are observed under a certain range of condition. This effect is found to be comparable with the scale effect.

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This paper describes equipment that computes and displays biomechanical quantities, such as joint moments, joint forces, and the center of gravity, together with symmetric motions of subjects with respect to the sagittal plane. These biomechanical quantities are computed in real-time on the basis of inverse dynamics by measuring the marker positions using real-time image processing on body movements captured by a CCD camera. These biomechanical quantities are displayed in real-time on an LCD projector screen and accordingly the subject can recognize the qualities and quantities of the motion as he or she is performing the motion. The real-time motion analyzer was used to analyze bowing, bending and stretching, and sit-to-stand motions, and it was found to be advantageous for coaching and self-education to learn optimal motions based on body mechanics.

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The flame appearance, temperature profile, and NOx emission associated with gaseous and liquid fuel furnace combustion are investigated through a series of experiments. Numerical simulations are also conducted, for several cases, in order to complement the experimental data. Three fuels, namely, hydrogen, propane, and Jet-A (C₁₂H₂₃), which is a liquid fuel, are examined. Combustion is carried out in two 840-mm long furnaces with diameters of 95 and 182 mm, respectively. Combustion air is introduced to the furnace through two coaxial air nozzles, which generate air velocity difference ΔUa. The flame appearance, temperature profile, and emission index of NOx (EINOx) of gaseous fuel combustion are found to depend strongly on the furnace diameter, D. The results indicate that gaseous fuel combustion can be characterized according to the furnace volume. In addition, the temperature profiles reveal that larger values of D and ΔUa result in lower temperatures. The EINOx is demonstrated to be well scaled with a parameter DU_fΔUa. Finally, the normalized EINOx is shown to be inversely proportional to DU_fΔUa because of the effects of dilution and flame stretch. However, the vaporization process in liquid fuel combustion appears to weaken the sensitivity of the normalized EINOx of Jet-A combustion on the parameter DU_fΔUa.

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In a sustainable city, public transportation is prohibited from emitting greenhouse gasses. To reduce emissions of carbon dioxide, a major greenhouse gas, a vehicle running on electric power generated from a green energy source is optimal because it does not emit carbon dioxide. With this goal in mind, we propose a public transport system consisting of electric buses that are charged intermittently at every bus stop using electric power generated from green energy sources. Such a system resolves the problem of low mileage per charge for heavy batteries. This system would also be able to effectively use low-density and widely available solar energy for generating power at bus stops that are widely distributed throughout a city. One major problem in realizing this system is the development of the charge-boosting system. And lightning of the storage device mounted on the bus is also key problem. We therefore begin by examining the features of typical storage devices. Next, we investigate issues involving the design of the charge-boosting system at the bus stop and the storage device on the bus. Finally, we perform a model experiment using a single-passenger electric vehicle. We find that a vehicle containing a designed storage device and running on electric power generated from solar energy can repeat the cyclical operation of running for approximately 90 s, stopping 20 s for charge, and accelerating fully charged from the bus stop for 4 s. The result is that the model experiment validates the proposed transport system design.

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The authors research the jet from an asymmetrical two-dimensional nozzle, especially concerning the effect of the lip length of the nozzle. Experiments are conducted at a Reynolds number of 6000. The aspect ratio of the nozzle exit is fixed to 300. And, the lip length is 0, 2.0h, 3.3h and 5.0h, where h denotes the height of the nozzle exit. Using a hot-wire anemometer, the authors show mean-velocity and turbulence-intensity profiles at various downstream sections, in order to reveal fundamental characteristics of the jet in both the near and far downstreams. Furthermore, in the near downstream, the authors visualise the flow by glycol smoke so as to get quantitative information using a PIV technique, and perform the dominant-frequency measurements to reveal flow-instability characteristics.

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Cavitation-induced vibration and erosion of pipes is a potentially damaging factor in piping systems. To prevent it, a detection method for cavitation phenomena should be developed. In power plants, especially, it is desirable to detect them from outside pipes during operation. Detection of cavitation phenomena was experimentally investigated in this paper using accelerometers mounted on the outer surface of a pipe upstream and downstream from an orifice. The following results were obtained. (1) With the progression of cavitation, output voltage of the accelerometer varied, and the amplitude and number of the pulse-shaped signals increased. However, it would likely be difficult to distinguish them from noises in an operating plant. (2) It was difficult to recognize the characteristic frequency of cavitation, because the power spectrum density was broad up to the accelerometer limit of 45 kHz. (3) The flow directional distribution of RMS (root mean square) values of accelerometer output voltage varied greatly with the progression of cavitation. Therefore, from comparison of RMS values obtained upstream and downstream from the orifice it seems possible to detect cavitation phenomena in the piping systems of operating plants.

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This paper describes the performance of a micro vertical-axis wind turbine with variable-pitch straight blades. The proposed variable-pitch angle mechanism has an eccentric point that is different from the main rotational point. One feature of the mechanism is its ability to vary the pitch angle of the blades according to the azimuth angle of the main links, without actuators. The performance of the wind turbine was measured in an open-circuit wind tunnel. The performance of the vertical-axis wind turbine with variable-pitch straight blades was better than one with fixed-pitch blades. A wind turbine with variable-pitch straight blades has wind directivity. It was found that the performance of a wind turbine is dependent upon the blade offset pitch angle, the blade pitch angle amplitude, the size of the turbine, the number of blades, and the airfoil profile.

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Low frequency noise is not clearly defined but is generally taken to mean noise below a frequency of about 100 Hz. Noise occurring at frequencies below 20Hz is often referred to as infrasound and this type of noise presents even greater difficulties in its countermeasure and assessment. The objective of our study is to suggest practical means of reducing the low frequency noise emanating from the opening of soundproof houses. This paper describes an experimental study on the alleviation of low frequency noise by the standing wave control in a soundproof house. As a result, about 3dB of low frequency noise reduction has been achieved at the reference point over a 1/3 octave band range of 200 Hz, which is the conversion frequency of 16 Hz for a real soundproof house. In the case of combination, the standing wave control and expansion type silencer, maximum noise reduction has been reduced by about 12 dB.

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