A mid-story seismic isolated building has isolators at mid-story and it is a good candidate for seismic retrofitting. Elevators for mid-story seismic isolated buildings receive strong rail bending stress due to the floor gap at the isolated floor. To reduce rail stress, a new elevator system has been established that has a long rail support span at the isolated floor. But it has complicated dynamic behavior including large rail deformation and guide contact with the rail. To evaluate such dynamic responses, we developed a nonlinear finite element model. Simulation results were validated by experiments, with the model. After precisely checking the rail bending stress, we derived an optimal elevator design against earthquakes.

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The present paper examines a method for the design of a spatial filter for suppressing modal observation spillover. A type of modal filter was proposed for eliminating several selected modal amplitudes from structural vibration responses. This filtering methodology can be realized by a small number of sensors, relative to the number of dominant modes in the frequency range of interest. The proposed filter can be designed using sensor placement to realize that the two subspaces, which are respectively spanned by a spatial filter vector and the selected target modal vectors, are orthocomplementary. The observation modal spillover associated with these selected modes is then suppressed. The effectiveness of the proposed filter was verified numerically for a cantilever beam and simulation results demonstrated potential for suppressing spillover in vibration control and health monitoring.

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The flow-field and the acoustic-field around moving bodies are simulated by the Arbitrary Lagrangian Eulerian formulation in the finite difference lattice Boltzmann method. The validity of the ALE is checked by comparing flow about a square cylinder in ALE formulation and that in the fixed coordinates, and both agree very well. Matching procedure between the moving grid and fixed grid is also considered. The proposed method in which the both grids are connected through buffer region is shown to be superior to moving overlapped grid. Dipole-like emissions of sound wave from harmonically vibrating bodies in two- and three-dimensional cases are simulated. Sound wave emitted from rapidly rotating elliptic cylinder is also successfully simulated.

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The attenuation characteristics of a slit resonator that combined the adaptive feedback ANC system at a ventilation aperture of the package for leakage noise is investigated. The discrete tones radiated from an AC axial flow fan are controlled by DSP using Filtered-X Least Mean Square algorithm. The attenuation is found at the range of: 3dB-14dB with circular slit resonator, 2dB-15dB with elliptic slit resonator. Results of measurement show that the proposed system can achieve TNR(Tone to Noise Ratio) and PR(Prominence Ratio) under threshold effectively.

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This paper proposes a structural topology optimization method for obtaining mechanical structures incorporating desired vibration characteristics for the design of mechanical resonators and vibromotors. First, a new type of homogenization design method is introduced, in which continuous material distributions are assumed using a continuous interpolation function at each node, in order to overcome numerical instabilities such as checkerboard patterns. Next, three design requirements for implementing specific vibration characteristics in the mechanical structures are clarified, namely eigen-frequency matching, eigen-mode control, and stiffness, and the corresponding objective functions are formulated. A new type of multi-objective function incorporating these three objective functions is proposed. The optimization problem is formulated using this multi-objective function, and an optimization algorithm is developed using Sequential Linear Programming (SLP). Finally, several examples are provided in order to confirm the usefulness of the generated optimal designs for vibrating mechanical structures.

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The effects of the Helmholtz resonator on combustion oscillation stabilization have been investigated for-gas-turbine-combustor, and mechanism of Helmholtz oscillation control has-been-discussed. Numerical model, based on compressible Euler equation including combustion chamber and resonator and is proposed in order to describe the behavior of acoustic wave excited by dynamic heat release of flame in combustor. Relaxations of acoustic oscillation amplitude corresponding to resonator parameters and such as throat diameter and are calculated and compared by atmospheric combustion experiments. In case resonator is resonant to combustor and it is shown that oscillation amplitude can be minimized. However and effectiveness of resonator is lessened with decrease of throat diameter and while throat diameter is tuning parameter of resonator. Resonator parameters must be optimized in terms of attenuation characteristics as well as resonant frequency.

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The combination of a burner and a combustion chamber is an important factor controlling flame characteristics. However, to our knowledge, this factor has yet to be investigated systematically. In the present study, coaxial jet diffusion flames in cylindrical combustion chambers have been studied in terms of inner diameters of the combustion chambers, global equivalence ratios, and turbulence in airflow. A fuel nozzle is composed of a stainless steel tube having an inner diameter (i.d.) of 2 mm with a coaxial pilot burner of 3.19 mm i.d., surrounded by two air coaxial tubes of 12 mm i.d. and 30 mm i.d., respectively. The inner and outer air tubes are for higher and lower airflows, respectively, and the turbulence in the airflow is changed by the velocity difference. The main fuel is propane. Hydrogen is used for the pilot flame, with a volumetric fuel ratio of 0.3. Each wall of the combustion chamber is made of a heat-resistant glass Pyrex tube so that each flame can be visualized. The inner diameter of the furnace is varied in order to investigate the effect of furnace size on the flame characteristics. The increase in the diameter of the combustion chamber has been found to enhance the exhaust gas self-recirculation, because the NOx emission decreases. The increase in turbulence in the airflow strengthens the entrainment of the exhaust gas transported upstream by the recirculation vortex. The increase in the global equivalence ratio from 0.2 to 0.8 in the present study decreases the oxygen concentration of the exhaust gas and leads to diluted combustion through the exhaust gas self-recirculation. A proper combination of these factors has been found to yield a low NOx combustion.

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The performance of a system for simultaneous air conditioning and domestic hot water heating is estimated numerically in this study. The system consists of air cycle refrigerator, desiccant rotor, evaporative cooler and heat recovery heat exchanger. The system uses air and water which are natural and safe substances. The system can supply air at low temperature and humidity. Also, it is easy to control the humidity of supply air by using evaporative cooling process before supplying air to the conditioning area. A recovery of exhausted heat from the desiccant rotor significantly decreasing not only the consumption of primary energy for heating domestic hot water but also the calefaction to the surroundings due to the rejection of heat. The system can supply hot water at a significant high temperature. The proposed system coefficient of performance is greater than the coefficient of performance of conventional system composed from vapor compression cycle and gas heater.

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Heat transfer was investigated experimentally for high pressure ratio air flow in square minichannels, which were machined on the oxygen free copper block. The sizes of the channels were 0.3, 0.6, 1.0 and 2.0mm, and the length were 10, 20, 50 and 100mm. The pressure ratio was changed widely up to the flow choked at the exit. It was found that the heat transfer coefficient was about 7.3 times greater than fully developed turbulent pipe flow. Experimental result showed that 75 percent of the total heat was transfered in 10 percent inlet portion of the channel.

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An on-board measurement system that can simultaneously obtain such information as road infrastructure, traffic conditions, driver's operations, vehicle running conditions, and exhaust mass emissions was installed in a light duty freight vehicle with an EGR system and in a minivan without an EGR system. In order to analyze the mechanism of roadside pollution caused by vehicles, road tests were carried out in real traffic conditions. The light duty freight vehicle showed intensive NOx pollution at the roadside in a vehicle start, in which the EGR rate was low, but it was effective to reduce NOx mass emissions at low speed running in traffic jams where the EGR rate was rather high. In the case of the minivan, intensive NOx pollution was observed in low speed running such as in traffic jams. The reduction of NOx during vehicle starts is important for vehicles with an EGR system to reduce intensive NOx pollution at roadsides.

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In order to clarify the reason why the NOx emissions factor becomes higher with vehicle acceleration at intersections etc., two freight vehicles of different emission model years, equipped with EGR systems for reduction of NOx, were tested by an on-board NOx measurement system. Higher NOx emissions factors were observed at vehicle starts in lower-gear operations for each vehicle though the total NOx mass emissions of the later model vehicle were less. Larger NOx mass emissions were clearly observed in the engine operation area of lower engine speed and load in real traffic conditions though the NOx mass emissions in steady state conditions was less. NOx emissions characteristics were analyzed in view of engine torque, NOx mass emissions, and the EGR rate, and considering the rate of engine speed change. It was found that lower-gear operations made the rate of engine speed change higher and also the EGR rate lower resulting in higher NOx emissions. This seems to be one of the factors to engender the intensive NOx pollution at roadsides.

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A short expansion chamber in a duct acts as a resonator type muffler. The properties of this type of chamber have already been studied in detail by the authors for circular duct-chambers. In this paper, short chambers are applied to rectangular ducts. These chambers consist of two rectangular branches located symmetrically on opposite sides of a rectangular duct. The transmission properties of plane waves through the chambers were examined experimentally. For a very short axial chamber length, the resonant frequency was determined in the same manner as for a side-branch muffler with open end correction. Though considered proportional to depth in circular chambers, it becomes constant in rectangular chambers with fixed axial length, regardless of chamber depth. When the chamber length is close to half of the chamber height (corresponding to the upper limit of resonator-type mufflers), the resonant frequency is close to, but in excess of, the cut-off frequency of the chamber's second resonant mode. The reason for this discrepancy becomes clearer subsequent to examination of the sound field contours calculated using the finite difference method.

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The present study is a technical report of the multi-objective design optimization of the two-dimensional shielding effect for the reduction of aircraft engine fan noise. The design optimization has been performed for the simplified cross section of aircraft with fuselage and plane wing. Two objective functions are considered for minimizing the sound pressure level at the side and the bottom locations relative to the fuselage, where standard measuring locations are defined by International Civil Aviation Organization. Those values are evaluated by using the linearized Euler equations. Since a wing, which is defined as a plate without thickness, is assumed as a V-tail wing, it is described by using the length and cant angle relative to the fuselage. The kriging-based response surface model is selected as an optimizer for the reduction of optimization cost. As a result, it is revealed that engine fan noise described by a monopole sound source is reduced by the shielding effect. Moreover, there is no tradeoff between two objective functions, i.e., the sound pressure levels at the side and the bottom measuring locations can be simultaneously reduced. As it is better that the wing length is as long as possible, the cant angle is essential for the shielding effect to reduce engine fan noise.

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This paper describes vibration analysis using the finite element method (FEM) for a viscoelastic block supported by a nonlinear concentrated spring. The restoring force of the spring exhibits cubic nonlinearity and linear hysteresis damping. The finite element for the nonlinear spring is expressed and is connected to the viscoelastic block, which is modeled using linear solid finite elements taking into consideration the complex modulus of elasticity. Further, the discretized equations in physical coordinate are transformed into nonlinear ordinary coupled equations using normal coordinate corresponding to the linear natural modes. Note that modal damping is also transformed without inconsistency in this procedure. This transformation can save computational time. Further, by applying the harmonic balance method to the transformed equations, steady-state nonlinear frequency responses are computed with fairly small degree of freedom. The influence of Young's modulus of the blocks on the nonlinear responses is clarified. Moreover, the influences of dissipated energy on the nonlinear frequency responses for the viscoelastic block are clarified.

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With the goal of developing advanced hydrogen combustors for micro gas turbines with low NOx emission at high temperatures up to T_it=1700°C, single coaxial injectors with two-staged (RQL; rich-quench-lean) combustion method were built, based on the excellent combustion features of hydrogen. The injector consisted of an inner pipe issuing rich premixed gases, and an outer concentric annular hole injecting secondary air at high velocity. The combustion characteristics of small test combustors, which had the injector and a combustion tube of 30 mm diameter, were examined at room temperature and atmospheric pressure, concerning NOx emissions, temperature distributions, combustion efficiencies, total pressure losses and flame stability limits. The optimum equivalence ratio of the rich premixed inner flame was confirmed to be about 2.0 for the viewpoint of decreasing NOx emission and total pressure loss. The NOx concentrations were reduced by decreasing the area of the coaxial air hole, and were in inverse proportion to the ratio of the momentum of the coaxial air to the premixed gas. For the injector with the smallest area of air hole, having pressure loss of below 4%, NOx emission levels were low enough, and high combustion efficiencies over 99.95% were attained in the range from 0.3 to 0.6 of overall equivalence ratio, since mixing in the second stage was so rapid. It was confirmed that this type of injector was suitable for two-staged RQL combustion.

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Environmental changes due to global warming greatly influence ecological systems including those of plants. Diagnostic technologies using non-destructive inspection methods to evaluate environmental stress are few. Acoustic emission (AE) is applied to plants under water stress and the damage is measured. Cavitation phenomena are created by negative pressure in plants because of the lack of water in vessels or tracheids. Since shock waves due to cavitations create AE, the water stress state of plants can be monitored in real time by measuring AE. In this paper, AE events due to cavitation were measured in the drought-treated Ginkgo biloba L., Ficus spp., and Lycopersicon. In all plants examined, AE events increased during drought. In a short-term drought experiment, AE events were stopped by supplying water, but not in a long-term drought experiment. In Ginkgo biloba L. and Ficus spp, a temporary decrease of AE events was observed during drought. Plants adjust their internal water balance through certain self-defense mechanisms.

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This study has investigated the characteristics and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. 100 roof tiles were set up in 10 lines and 10 rows on a pitched roof in the downstream of the flow from a wind tunnel. These experiments were followed by series of tests where the slope angle of the roof tiles was changed. The vibrations of the roof tiles were simultaneously measured by the two accelerometers, and the motions of the vibration and scattering were observed by the high-speed video camera. The frequency response function and coherence function of roof tile were measured by an impact hammer test under no flow condition. Just before scattering of the roof tiles, both vibrations of a higher frequency mode and vibrations of lower frequency mode appeared simultaneously in the roof tiles. The values of the higher frequencies were corresponding to the values of resonant frequencies of the roof tiles. It was thought that the scattering of roof tiles was influenced by the vibration of the lower frequency mode. The frequencies of the vibration were measured by a high-speed video camera system. The values of the lower frequencies were 10Hz∼20Hz. The mechanism of the scattering of the roof tiles could be understood by means of the information from the accelerations and the images of roof tiles.

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The transient response characteristics of the power supply of a small-scale fuel-cell co-generation system, constituted from a reformer, a fuel cell stack, an inverter, an interconnection device system with a changeover switch, and auxiliary heat sources were investigated. Furthermore, the relation among the settling time, time constant of the reformer and the fuel cell, and the setting values of the parameter in PI control was analyzed. By changing the PI control parameters according to the reforming load, the setting time is shortened. Moreover, the operating cost of the system was estimated, with reference to the power demand and heat demand pattern of individual houses in Sapporo and Tokyo. Consequently, the annual balance of payments achieved by installing a heat pump system with COP=3.0 into the fuel cell system shows a favorable balance in Tokyo, and a passive balance of about zero in Sapporo respectively.

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A numerical simulation of swirling flows in a cyclone separator has been performed using a large eddy simulation (LES) based on a Smagorinsky model. The validity of the simulation and the nature of complex flow characteristics are discussed in the context of experimental results. In this work, particle motion is described using a one-way Lagragian method. Particle separation performance is assessed from particle tracking results. A result of this study investigation demonstrates that the LES has been sufficiently capable of predicting the complex swirling flows in a cyclone separator.

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This paper deals with a forced vibration of strongly coupled subsystems. A theoretical and practical approach is proposed to obtain targets of the subsystem's vibration properties which fulfill the target of whole system. The approach is an application of transfer function synthesis method and provides a procedure to analyze the compliance of subsystems at connecting points for setting the natural frequency and reducing the internal forces. A new concept of kernel dynamic stiffness and kernel vector is introduced to understand vibration transmission in the analysis of the compliance at connecting points. This approach is applied to vehicle noise issue induced by road roughness (road noise) in the frequency range of 80Hz and 150Hz on macpherson strut type suspension. The results show effectiveness of this approach and present guideline of the suspension design for road noise.

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