Last time, we reported the applicability of the simulation using the fluid sound analysis based on comparison of the simulation result with the measured result of the noise of the actual traction motor. (hereafter referred to as device) This time, we report that by optimizing the noise source condition, the simulation result has approached the measured result of the noise of the device. Now we can design an optimum device without manufacturing the device, based on estimation of the noise generation status inside the device by the simulation using the fluid sound analysis.

View full abstract

It is difficult to clarify the mechanism of the generation of aeroacoustic sound experimentally because unsteady behavior of the spatial distribution of vorticity need to be measured precisely. Using time-resolved Particle Image Velocimetry, we conducted the experiment to measure the flow field and aeroacoustic sound around a cylinder simultaneously. From the temporal data obtained by PIV, we calculated the spatial distribution of vorticity and estimated the sound pressure in the far field, applying Howe's vortex sound theory. Through comparison with the actual sound pressure measured by a microphone, it is assured that PIV estimated sound pressure is correlative with the actual sound pressure.

View full abstract

The three dimensional structure of the wake vortex was investigated in relating to the aeolian tone from the inclined flat blade, which is installed in the uniform flow from zero to thirty degree of the inclined angles with upper and lower wall. It was pointed out that the aeolian tone is largest not at zero, but at ten degree of the inclined angle. The pressure fluctuation to generate the aeolian tone on the surface of the blade is closely relating to the formation of the shedding vortex in the wake. The strength of the vortex is almost constant in small inclined angles, but the scale of it in span direction becomes large at small inclined angles. The span wise correlation of the wake vortex at zero inclined angle is only restricted near the position of that the shedding vortex forms and gradually decreased with the retarded time. But the correlation at small inclined angle is moved in span direction with the span-wise velocity in the dead air region. The wake vortex is classified in span direction to the locally small cluster and the large one. The aeolian tone is closely related to the large cluster of the wake vortex. The delay of the wake vortex formation is occurred in span direction with the large cluster. The estimation of the correlation length is proposed in relating to the delay of the wake vortex formation. The estimation of aeolian tone by the correlation length is good agreement with the experiments.

View full abstract

To clarify the mechanism of the broadband noise generated by the separated flow around a NACA series blade is aimed. The relation between the angle of attack and the broadband noise of the blade are analyzed by the wind tunnel experiment and a commercial CFD code. In the case of rear surface separation, the separated vortex that has a large scale structure in the direction of the blade chord is transformed to the vortical structure that has concentrated to the trailing edge with the increase of the angle of attack. Then the broadband noise level becomes small according to the vortex scale in the blade chord. The separation vortex of the low pressure is formed at the vicinity of the trailing edge when the flow is separated at the leading edge. The pressure fluctuation on the blade surface at the vicinity of trailing edge becomes large by the rotation of the vortex in the wake. The broadband noise level increases with the increase of the pressure fluctuation and the expansion of the correlation length by the vortex scale when the flow is separated at the leading edge.

View full abstract

The low frequency noise is not clearly defined but is generally taken to mean noise below a frequency of about 100 to 150 Hz. Noise at frequencies below about 20 Hz is sometimes referred to as infrasound and this type of noise presents even greater difficulties in its measurement 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 house.

View full abstract

A reactive type silencer like a side branch silencer is effective for the reduction of the sound with periodicity. It is often used to reduce the noise generating the pulsating pressure etc. This is especially effective for the noise with single frequency. However, an effective frequency range is comparatively narrow. Moreover, the silencer is obliged to be large for countermeasure of the low frequency sound. And, that might cause the problem of the installation space. Then, in order to develop the side branch silencer which is effective for the low frequency range, the side branch with the finite impedance at the end of it was made and examined. As a result, it was clarified that this side branch was able to achieve the objectives.

View full abstract

It is preferable to reduce the combustion noise of residential gas appliances from the view point of keeping the quiet living environment. To understand the generation mechanism of the combustion noise from a residential gas boiler, noise measurements and CFD analyses were carried out. As a result of those analyses, it was clarified that an oscillation arose in the combustion air flow at the inlet of the gas-air mixing pipe and the peak frequency of the oscillation coincided with the frequency of the combustion noise. This coincident oscillation was considered to amplify the combustion noise. It was found that the combustion noise reduction was achieved under the condition of controlling the coincident oscillation.

View full abstract

Some ceiling-mounted ventilators have the function of sound attenuation by a resonant effect in a chamber consisting of a rectangular outer cover and a cylindrical fan unit. In order to control the resonant properties in a reactive manner and maximize the sound attenuation effect of that resonant system, we separated the chamber by a partial shutting plate at the end of the inner cylinder into two spaces that are approximately expected to behave as a Helmholtz resonator of two degrees of freedom. In our former research, a chamber having a simplified symmetrical shape modeling the real chamber concerned was located in a duct of infinite length. In this research, we attach the chamber at the end of a duct and examine the properties of the sound radiated from the duct end to a free space experimentally and numerically (BEM). Every effective frequency for sound attenuation is the same between two cases : (i) the chamber is located at a duct end ; (ii) the chamber is located in an infinite duct. However, some differences between two cases are also revealed. The situations of the differences are precisely studied through examining the sound fields in and around the chamber. The most notable difference between two cases is that the sound is amplified by means of the chamber in a low frequency range in case (i). Fortunately, this is not serious for a real ventilator because the corresponding frequency range is not dominant for sound radiation of a real ventilator.

View full abstract

In order to control the vortical structure in the wake of a sphere, the active flow control technique using acoustic excitation was utilized. The vortical structure in the wake of a sphere is divided into two different types. One is the alternative vortical structures such as the Karman vortex street. The other is the helical vortices. In the natural condition, one structure becomes superior, but those structures coexist. Therefore, these structures are unsteady. We attempted to control these structures with the acoustic excitation. The structures depended on not only the frequency, but also the acoustic mode. The results showed the acoustic fields influence on the wake structures. Then the acoustic excitation seems to be effective for the flow control with small energy

View full abstract

The acoustic transparent wall is a plate through which sound can pass easily but flow cannot pass. It is composed of a thin film, clothes and wire nets. In this paper, acoustic reflection coefficient of acoustic transparent walls was measured under the pressurized conditions. It was increasing according to the inside pressure, and this tendency was remarkable in the case with fine outer mesh. Based on some simple analysis, this phenomenon was supposed to be caused by increase of the film tension according to the inside pressure.

View full abstract

This paper describes the controller design of an active feedback noise control system in an enclosure surrounded by rigid walls. A large number of operations is required for active control in a rigid-walled sound field because lots of acoustic paths between multiple sensors and multiple secondary sources can exit. The rigid-walled sound field can be expressed by the superposition of a large number of orthogonal acoustic modes. It is expected that single-input single-output (SISO) model can be achieved for each mode independently using the modal decomposition and generation technique. Therefore, an active control system with SISO H^∞ controllers to suppress multiple mode amplitudes independently based on the modal decomposition and generation technique has been proposed. In the present paper, verification of the characteristics of the proposed system to control four modes is carried out numerically and experimentally. The results show that noise reduction can be improved with designed SISO controllers.

View full abstract

We have proposed a noise control system that the noise insulation panels with piezoelectric material arrange, and enable the transmitted noise through a target plate to reduce by suppressing the vibration of the noise insulation panels with a simple analog control circuit. In this paper, after the equivalent mechanical models for a number of the piezoelectric material are shown, a method for expansion a control frequency range is demonstrated as the performance advances of the noise control system. In the experimental results, it is verified that the noise transmitted through the noise control system reduced with range of frequency.

View full abstract

When the noise sources are set up in the space where it shuts oneself up, the frequency of the noises source are corresponding to the natural frequency of the space, and the noise is amplified. Especially, the standing wave is caused easily by the low frequency noise, because the effect of the absorption and the insulation is small, and the wavelength is near the size of the living space. It is difficult to decrease the low frequency sound. Therefore, it is important to predict the resonance beforehand, and to evaluate the influence of the low-frequency noise. Then, the accuracy of the low frequency noise prediction by the computer simulation was experimentally verified, and the practicality was confirmed.

View full abstract

Porous duct is effective to attenuate resonant sound of engine intake systems. When we design that system reasonably, we must decide proper length and suitable position of porous duct set in that system to attenuate resonant sound effectively. We proposed the method to determine the transfer matrix of porous duct, which is important for acoustical analysis of that system.

View full abstract

This paper describes the case of condition monitoring for reciprocating compressor valves by acoustic technique. The valve plate is the most fragile part of reciprocating compressor and once valve is broken, compressor tend to be in trouble. The leading cause of valves to be broken is tumbling phenomenon. This paper focuses on tumbling phenomenon of valves, and describes how to catch this phenomenon by condition monitoring system.

View full abstract

The device generating an infrasound used in field experiments was developed. This can generate continuous infrasound with pressure level around 110 dB at the distance of 3 meters within the frequency range of 5 - 20 Hz by using pneumatic servomechanism. This device is suitable for the investigation of the influence of an infrasound on fittings and the human body. This paper reports the overview of the device and some experimental results obtained by field measurements.

View full abstract

There are many noise sources around us even in the room such as an office room. Both simple and effective noise shielding devices are expected in such a room. As a practical active noise control device, an active noise shielding system is proposed in this paper. This active noise shielding system consists of microphones, a loudspeaker, controller and a general partition used in an ordinary office. Firstly, passive noise control effect with partition itself is investigated by numerical analysis and experiments. Next, active noise control effect with proposed active noise shielding system is confirmed through simulations and experiments.

View full abstract

The final target of this research is to develop 'Active Acoustic Filter' for a radiator cooling fan. It is set just in front of a radiator and reduces the fan noise. Active acoustic filter is constructed with many short ANC ducts, called 'cells', which have high open area ratio and low pressure loss. In this paper, as the first step, an ANC cell using a flat speaker was designed and manufactured trially. Based on some experiments, it is proved that the ANC cell can attenuate random noise in 300〜1700Hz by 10〜20dB.

View full abstract

On active noise control in 3-dimensional acoustic field, a control effect becomes worse when an evaluation point moves. Against this problem, we proposed control with filter map. In this algorithm, a control area is divided into small grids. Effectiveness of this algorithm was shown in simulations. In this paper, the validity of this algorithm is shown in several simulations and experiments in the anechoic chamber. The evaluation point moves 0.4m at the speed of 0.45m/s in experiment. A CCD camera catches a position of the point. From the experimental results, it is shown that the effectiveness of the proposed algorithm is 10dB more than the that of the direct adaptive algorithm.

View full abstract

This paper concerns the improvement of loudspeaker performance by shaping acoustic waveform in time domain using active control technique. In the audio-video equipment with thin-panel, the drive for ever thinner speakers typically results in shortcomings in sound quality compared with conventional box speakers. Because of unnecessary sounds radiated from speaker unit and box, it's impossible to reproduce the original sound perfectly. Then, the authors propose a method employing an adaptive impulse response control system with secondary speaker. This method is applied to the thinner box speaker and audio-video equipment of a thin type. The sound reproduction performance is verified on the basis of experiments.

View full abstract

This paper focused on a vortex typed structural intensity on plate. When the structural intensity distribution on the plate is kind to be in vortex, the vibration and the radiation sound levels are getting smaller and the radiation efficiency is drastically changed to be larger and smaller than the case of the non-vortex types structural intensity pattern. In this paper, it is firstly shown that the vortex typed intensity distribution is aroused by the excitation at near the nodal line. Then the modal expansion of structural intensity can prove the occurrence of the vortex intensity. Finally the relation between the structural intensity with vortex distribution and the low noise and vibration conditions is discussed.

View full abstract

Structure-borne sound radiation can be reduced by adding sound absorption to the surface of the structure using perforated plate. In this paper, a self-developed numerical analysis technique for sound fields including perforated plate is described. The technique is acoust - structural coupled analysis technique by applying boundary element method to the sound fields and applying finite element method to the perforated plate. Using the numerical analysis, the reduction of the structure-borne sound is predicted. The validity and usefulness of the numerical analysis technique is verified by comparing the analysis result with an experimental result.

View full abstract

As a new sound absorption material, micro-perforated aluminum thin plate has been developed to solve some problems of fibrous sound absorption materials. But its stiffness is not so large, so it is vibrated easily by sound pressure. And sound absorption performance is affected by its vibration to decrease the coefficient of sound absorption. This paper describes the relationship between the vibration behavior of micro-perforated thin aluminum plate excited by sound pressure and the sound absorption performance of that plate. The vibro-acoustic behavior was observed by using the laser scanning vibrometer, and the sound absorption coefficient was measured by two microphones method.

View full abstract

Double-leaf sound insulating wall is widely applied to cabins of air-plane or high-speed train, because transmission loss is larger nevertheless the weight is light. But transmission loss of double-leaf is decreased at the resonant frequency of the wall. So we tested resonators and tuned mass dampers to increase transmission loss at the resonant frequency. And we observed vibration modes of the surface of the wall and measured the transmission loss. Those results show that vibration modes which are generated by resaonators and mass tuned damper affect the sound transmission loss.

View full abstract

Railway noise is composed of various sources, such as wheel/rail noise, aerodynamic noise, traction-motor fan noise and bridge noise. The bridge noise is generated by vibration of steel or concrete bridges, which is mainly induced by dynamic forces due to the wheel-rail interaction. For the concrete bridges, the bridge noise is predominant below 500 Hz, and could have greater contribution to the total noise than the other sources at a measuring point close to them. Therefore, the bridge noise is increasingly being viewed as a problem that needs addressing. In order to put countermeasures in place to mitigate the bridge noise suitably, it is important to make a better understanding in terms of vibratory and acoustic properties of the bridges. In this paper, an attempt to examine the vibratory behaviours of three types of concrete bridge has been made through a numerical calculation by using FEM.

View full abstract

The noise caused by vehicle wheels rolling on conventional rails is becoming an essential problem in recent years. In this report, we introduce the results of an analysis regarding the noises as reduced and executed case studies. The noise caused by corrugated narrow gauge wheels is normally intense to compare with that caused by conventional wheels. As a countermeasure therefore, we manufactured a simple sound proof cover applicable to the corrugated wheels experimentally, and examined and sought the effects of vibrations and noise levels through analysis and experiments.

View full abstract

Fuel cell systems may be regarded as noiseless electric power plants, the reason being that combustion engines are not used. However, small blowers have to run in order to supply fuel gas and air to the cell stack, and this generates noise and vibrations. Small type fuel cell systems for home appliances should be quiet, similar to air conditioning systems for home use. The problem with louder noise and vibrations from a small blower composed with a twin-screw rotor arose in the first version of developing this small blower. Non-contacting sensing of vibrations in the blower casing and the rotors was examined with the laser doppler vibrometer to clarify the mechanism of the vibrations. Also, a numerical analysis of the vibration characteristics of the blower was executed by FEM. It was recognized that the electromagnetic fluctuating force induced by the motor excited the natural vibration mode of the twin rotor. Optimizing the magnetic intensity of the magnetic coupling in order to smooth the fluctuating force and adapt a damping effect in the rotors was attempted to improve the large vibration mechanism. Finally, we achieved permissible quietness and low vibration levels radiated from the improved small blower.

View full abstract

We applied impact damper system to one degree of freedom vibration system. At this system, a rotating impactor with eccentric mass was employed. We investigated damping characteristics of the impact damper system theoretically by using created numerical simulation program of this system. Furthermore, we calculated mechanical energy of the impact damper system, and investigated the mechanism that the damping effect is improved by eccentric mass.

View full abstract

In general, a large amount of noise is generated due to rail vibration derived from train passage on a rail joint. Therefore an effective countermeasure and easy to install against the noise generated around rail joint is requested to be developed. We have further developed a new material for rail joint named "Noise Insulating Material for Rail Joint". The structure of this material is consisted to two layers ; one is material of bounded inorganic particles such as silicates for inside, and the other is sound insulating plate such as plastic for outside. This material is installed at a place about 100mm distant from rail in order that the rail can be inspected after installation of the material. As the results of impact test and track motorcar test executed at the rail joint in Hino civil engineering testing station, it has been revealed that the material is effective for reducing the noise radiated from the rail joint.

View full abstract

The new practical method has been developed to analyze multi layer noise transfer paths. The method evaluates transmissibility of the sound and vibration between each of the layers as transmissibility matrix. Thus the noise transfer paths from multiple sources can be represented by a series of sound and vibration transmissibility matrices. Applications of our method to the cabin noise of construction machinery showed that the method could identify the dominant noise transfer path, analyze the noise generation mechanism and predict noise reduction effect.

View full abstract

The method of transfer path analysis by actual measurement data was applied to structure-borne sound of vacuum cleaner. The contribution of each transfer path was obtained by using the transfer path model consist of three layers, and the path with large contribution was identified. And, the noise reduction of the structure-borne sound about 5dB was achieved by giving the vibration insulation structure to the transfer path with large contribution.

View full abstract

This paper describes a structural optimization method for SEA subsystems which realization of the desired value of loss factors is necessary. The authors developed a structural design process on the basis of experimental SEA for reducing structure-borne sound in real-world machinery. The process identifies the loss factors which need to be changed in order to effectively reduce the structure-borne noise emitted from machinery. The authors studied the FEM-SEA method, where the evaluation of the coupling loss factors was performed with respect to the target subsystem instead of the entire system. The structural optimization method is based on a combination of FEM-SEA method and an optimization procedure. In this paper, the proposed method for the structural optimization is applied to an actual machine. The optimization method is shown to work well at the target frequency band under arbitrary constraints.

View full abstract

Various sounds exist in the environment that we live. It is known that these sounds influence man's psychology or the physiology. By the way, there are not a lot of researches on the good influence that the sound exerts on man. Then, we applied the focus to the sound that existed in the forest and meadow, and evaluated the characteristic of these sounds. Moreover, the influence that the sound of nature exerted on man's psychology was examined by the questionnaire survey simultaneously with this. The relation between the frequency and the power spectrum was clarified by using the FFT method about properties of sound. Moreover, the influence on man's psychology did the principal component analysis that used the semantic differential method. The influence that the frequency response of the sound that existed in natural environment exerted on man's psychology was quantified by synthesizing these analytical results.

View full abstract

In recent years, with the never ending progress in technology related to audio visual equipments and PC, etc., there is an increasing trends of using the reproduction sound of contents such as music and speech even for household purposes. Since all the phenomena occurring in nature need to be considered in relative frame of reference, a pleasant and enjoyable sound to the listener may appear as a noise to the people (non-listener) around the owner of sound player. Therefore, the aim of the present work is to develop a sound field control technology which confined the sound field to the listener only. In this regard, the author first focused his attention to the relation between the vibration area of the speaker and the attenuation ratio. Based on that is proposed a method to change attenuation ratio so that sound pressure level remain same in the near field, but its level reduces in the far field. In this technique, the primary and secondary sound source of different vibration area is interacted by using antrphase of the primary sound source. Based on the experiment and theoretical estimation the performance of the present technique is verified. In addition, the present performance in a real environment is estimated.

View full abstract

As the birthrate decreases, the labor shortage of young generation becomes social problem. In order to solve this problem, it is necessary to establish the social surroundings in which parents with the infant are able to work feeling easy. Then, the author has been proposed the system giving peace of mind to the infant in the nursery by transmitting the heartbeat rhythm of the working parent through the Internet and reproducing it in the doll held by the infant, and giving peace of mind to the parent by transmitting the heartbeat rhythm of the infant and reproducing it by the portable heartbeat simulator like a wrist watch. In this study, the evaluation experiments are carried out to confirm the followings : the infant shows good reaction in the heartbeat rhythm of the mother, and the mother is able to recognize the infant heartbeat rhythm by the portable heartbeat simulator. As the result, it is clarified that the proposed system has the ability of giving peace of mind to both of infant and parent.

View full abstract

Amid ongoing super-aging society, the introduction of portable medical equipment is promoted with the expanse of patient's activities. As a result, this study will focus on noise and vibration of the portable medical equipment with air compressor, and investigate the effects on the human body and surrounding environment.

View full abstract

Development of tar removal from gasified gases is one of the most important issues for thermal gasification of organic waste such as woody debris. Using laboratory-scale catalytic reformers and gasifier, characteristics of tar removal using porous silica and availability of catalyst and porous silica regeneration were discussed. Commercial Ni-based catalyst and several kinds of porous silica, which has different surface areas, were applied to the reforming reaction. From gasification and reforming experiments using woody waste, application of the porous silica led to reduction of highly-polymerized polycyclic aromatic hydrocarbons (PAHs). When catalyst regeneration by air oxidation was carried out at around 1030 K, which is also reforming temperature, hydrogen concentration was almost sustained in the second reforming operation or later. It was also shown the catalyst would have enough reforming activity at relatively low temperature condition.

View full abstract

A rice husk is one of agricultural wastes, but useful non-eatable biomasses because it contains 70〜75 mass% organics and about 15 mass% amorphous silica. The objective in the present study is to fabricate high-purity amorphous silica materials originated from rice husks by using citric acid leaching process, not employing the conventional strong mineral acid solutions. The GCMS analysis indicated the citric acid solution was effective for the hydrolysis reaction of cellulose and hemi-cellulose contained in rice husks, and the reactivity increased with increase in the aid concentration of the solution used in leaching. At the same time, the metal impurity contents, such as K, Ca, Mg, Al, were also reduced after citric acid leaching process due to the chelate reaction between their impurities and the carboxyl group (-COOH) of the citric acid solution. As a result, the silica materials with high-purity of 99% or more were obtained from the rice husks.

View full abstract

For the purpose of developing a low cost liquefaction process, rapid pyrolysis of woody biomass has been investigated using an entrained flow reactor. In the bench-scale entrained flow reactor, cedar particles were rapidly pyrolized and the products were analyzed. The yield of liquid products was up to 50wt% compared with the fed biomass in dry weight. The moisture of liquid products should be removed and the products are expected to use as alternative to heavy fuel oil.

View full abstract

In this paper, firstly, property, combustion quality, and exhaust gas characteristics of sewage sludge-derived pyrolysis oil were analyzed. Secondly acceptance of biomass fuel and pyrolysis oil was interviewed to sewage sectors and consumers. As a result, followings were clarified : i) the calorific value can be improved by deoxidization ; ii) nitrogen content influences exhaust gas characteristics ; iii) each sectors have their own recognition and acceptance of environmental values for biomass and pyrolysis fuels.

View full abstract

An activated carbon with high micro- and mesoporosity, as well as a high bulk density, was fabricated by activating the extrusion-molded precursor made from carbonized rice husk (RH) and beet sugar (BS) at 850℃ in CO_2. The pore structure of this RH-based activated carbon (RHAC) was analyzed in relation to the bulk density. The extrusion molding was very useful to increase the bulk density when compared to the press-molding. RHAC which was first activated for 1 h was immersed again in the BS syrup and then activated in CO_2 for 2 h. This two-step activation process provided both a high bulk density (0.93 g/cm^3) and a highly textured structure (BET specific surface area : 844 m^2/g).

View full abstract

A procedure is being developed to process industrial and municipal wet wastes into solid fuel, called Refuse paper & plastic fuel (RPF), using a superheated steam drying system. Used disposable paper diapers are processed by the drying system as high moisture waste. The purpose of this study is to introduce a practical high moisture waste recycle system, and the results of this system are compared to the results with a conventional waste incinerator. The effectiveness of a drying system using superheated steam is shown from the standpoint of the reduction of CO_2 emissions and energy consumption for the waste processing. As a result, the superheated steam drying system applied to process high moisture waste and the obtained solid fuel provide an environmentally-friendly waste recycle system.

View full abstract

Recently, the process for high concentration saccharification has been focused in order to manufacture bio-ethanol. For short time and high concentration saccharification, the developments of an enzymatic hydrolysis process were demanded. In this study, the enzymatic hydrolysis process with a wet mill using sample of Japanese cedar wood powder and a solids-liquid separation by the filter press using the residue after the enzymatic hydrolysis process were carried out. As a result of this, the enzymatic hydrolysis process with the wet mill increased an initial saccharification speed and maximum saccharification ratio of holocellulose in case of 10% solids concentration of wood powder. And the residue and glucose solution collected by the filter-press were slightly unaffected by miniaturization of wood powder during the enzymatic hydrolysis process with the wet mill.

View full abstract

The effect of mixing on enzymatic saccharification with high solids loading of Japanese cedar powder pulverized by the inner power ring mill was investigated. The enzymatic saccharification examinations with three mixing states as vibration mixing by multitiered mesh structure, propeller mixing and no mixing were carried out on solids concentrations of 10, 25 and 40w/v% using acetic buffer solution of 800ml, a powder pulverized into 20μm in average diameter and an enzyme dosage of 20wt% per solids of powder. The saccharification ratio of vibration mixing achieved 60% for 10% solids concentration and 70% for 40% solids concentration. On the other hand, the saccharification ration of propeller mixing over 25% solids concentration achieved up to 50% that was equivalent to no mixing saccharfication. Therefore, the vibration mixing may allow for high solids loading during large scale processing.

View full abstract

The removal of chromium (VI) from an aqueous solution using persimmon tannin adsorbent was examined. The amount of Chromium (VI) removed was strongly affected by the pH of the solution. All amount of Cr (VI) was removed under pH2, howeber, the amount of that was decreased with increasing the pH of the solution using 15mg dry weight basis persimmon tannin adsorbent. A part of Cr (VI) was reduced other oxidation stage by persimmon tannin. The amount of Cr removed was increased with increasing the concentration of the Cr of the solution. The amount of Cr removed was fitted with the Langmuir isotherm.

View full abstract

Distillery residue of spirituous liquor Shochu contained many nutrients for livestock and is expected to be used as a feedstuff. However, difficulty of the preservation of this distillery residue prevents to use it as a feedstuff. To solve this problem, we first separate the solid part of this material by disk-separator and we condensed the liquid part by a multiple effect evaporator. The dry matter content of the solid part is about 30% and thus easy to be dried. The dry matter content of the condensed liquid portion is about 15% and can be stored long because of its high concentration of citric acid and low pH. Because of the fluidity of the condensed liquid, it is difficult to condense further. However, fluidity can be improved by adding yellow grease and by the treatments with enzymes such as cellulase, amylase etc. Some mixed treatments by these methods may be more effective to improve the fluidity.

View full abstract