This paper describes a simulation of diffusion phenomena by Cellular Automata. Cellular Automata are known as a class of modeling technique originally developed in the field of information engineering, in which the flow of information can be modeled systematically. In the application of Cellular Automata in other engineering field, local neighbor rules and transition rules are introduced instead of the governing equation, and the state variables defined on the simulation field are evaluated on each time step by these rules. In the present application, the degree of concentration is represented by the number of particles set on the field. All the parameters treated in this procedure are discrete ones.

View full abstract

The complex relationships of the momentum, heat, and water vapor within and above plant canopy have many important practical implications in micrometeorology, as well as in other areas, and have been evaluated by the micrometeorology model and observation in the plant canopy. In the present work, the one-dimensional plant-canopy model applied two turbulence models : one is k-ε model with consideration to vegetation resistance and the other is the turbulence model which is not considered vegetation resistance into the turbulence length scale. Furthermore, the radiation distributions of the plant canopy layers were calculated by the 2-stream model. In the purpose of this study, the model evaluates the relationships of the momentum, heat, and water vapor between the vegetation and the atmosphere. By comparing observed data of the planetary boundary layer collected in a deciduous forest in Pennsylvania, USA with the simulation result, it was assured that good applicability of k-ε model which is considered vegetation resistance. Therefore, according to the result of one-dimensional plant canopy model, it was found that condition of vegetation area density profile affected directly air flow within and above the plant canopy.

View full abstract

Photochemical ozone (O_3) is one of the most common types of pollutant in Japan. O_3 concentrations more than twice the environmental standard are often observed in Japan's big cities. In this study, we developed a comprehensive prediction model for atmospheric pollutants concentration, including O_3, nitrogen oxides (NO_x) and other pollutants. By using the model, we investigated the relationship between O_3 generation and emission levels of primary pollutants such as NO_x and hydrocarbons (HC) around Osaka bay area. We simulated to reproduce O_3, NO and NO_2 concentration on typical summer day. Diurnal variations of simulation results were similar to observations. Predicted pollutants levels couldn't reproduce perfectly. The results of the simulation suggested that O_3 concentration decreases with reduction in emissions of NO_x and HC. However, for higher emissions of NO_x, reduction in the rate of NO_x emissions leads to an increase in O_3 concentration above its uncontrolled value. Also, with decrease in O_3 concentration, the time when maximum O_3 value appeared tends to become late.

View full abstract

In recent years, there found are many places in which the concentration of nitrogen dioxide (NO_2) exceeds the environmental quality standard where automotive exhaust gas the likely to collect, such as road intersections at urban areas, underground parking lots, bus terminals, etc. The Acid Gas Eliminator removes nitrogen dioxide at an efficiency as high as 80%, and simultaneously it is also able to remove smoke and soot. To examine the effect of compact gas purification system, numerical simulations of airflow and pollutant diffusion in a two dimensional cross section were carried out. The calculated results show that the gas purifier works to improve the road side environment under low wind condition.

View full abstract

The purpose of this study is to obtain basic methodology for detecting danger on aged or handicapped people using acoustic signals. Firstly, kinds of danger that should be detected were narrowed down. This information was obtained by panel experiments that tested the limit of human danger recognition using only acoustic signals. Secondly, a signal processing system was developed for filtering out acoustic signals that represent danger. This system consists of wavelet transformation, homomorphic transformation, and hidden Markov process speech recognition.

View full abstract

In this study, "Comfort Index" calculated from the heartbeat fluctuation was proposed in order to objectively evaluate the comfortableness on the swinging of active rocking chair. The heartbeat was used by reason that the heartbeat sensor does not almost get on examinee's nerves. Then, it was confirmed by the evaluation experiment that "Comfort Index" was effective for the relative evaluation in the identical examinee. Next, the swinging of the glider motion style active swing chair was evaluated using the proposed "Comfort Index". In the result, it was confirmed that the swinging was comfort. And the validity of "Comfort Index" was also confirmed from the result of simultaneously carried out questionnaire that the swinging is equivalently comfort with the active rocking chair.

View full abstract

Evaluation of human impression for Acoustic Environmental Design at public space is very difficult and researched to generalize the methods day by day. This paper describes the second experimental results including consideration of seasonal difference and investigation of "Free Description of the Adjective" method for acoustic environmental design at public space. Evaluation results indicate that the Acoustic Environmental Design influences seasonal impression which subjects receive from the experiment space in winter and summer. In addition, new effects of Acoustic Environmental Design are observed by comparing the results at different seasons.

View full abstract

This paper deals with the results of sound quality study of vehicle warning signal using SD method and physiological effect of measured heartbeats at the onset of vehicle warning signal. The following five polar adjective scales were used, i.e., frightened-not frightened, pleasant-unpleasant, more warning-less warning, metallic-deep and powerful-weak for evaluations of test signal. Finally, the subjective ratings were correlated with the three psychoacoustical measures, namely, SPL (dBA), loudness (sone) and sharpness (acum) for determination of threshold values.

View full abstract

An effective and new method of reducing the noise of a HDD by a structural modification of cover was investigated in this study. The correlation between the noise characteristics of the HDD and the vibration characteristics of the cover, which is the main source of the HDD noise, is found from experiments. A theoretical analysis is performed to find the modification method of the cover, and this modification method is applied to the real cover of the HDD. The modification reduces the vibration of the cover transferred from driving motor. The effect of the modification is verified through noise tests.

View full abstract

To evaluate the sound quality of manual operation sounds of copy machines and laser printers, such as opening and closing front cover, drawing and loading paper trays, and locking and releasing hooks, the free description experiment using onomatopoeic representation was examined. The obtained onomatopoeic representations represent the acoustical properties such as the rubbed sounds with high energy in the high frequency region affect the sound quality of manual operation sounds. Furthermore, the subjective evaluation experiments of the product image were conducted to show the relationships between the product image and onomatopoeic features.

View full abstract

To compare the features of Japanese and Korean soundscape, the interview survey on sounds were examined for Koran people living in Japan. They were asked the noticeable sounds in living spaces, market places, transportation, parks, urban streets, and department stores in Japan and Korea. The characteristic sounds in Japan are announcements and music from peddlers' of roast sweet potato and ramen (Chinese noodle soup), craw caws, traffic audio signals for the blind, and songs of street musicians. The characteristic sounds in Korea are magpie cries, popular songs or radio sounds in busses, peddlers' cries in subways, ambient music on the street in the midnight, and sounds of rice candy makers. We can see the cultural differences of both countries from the differences between their soundscapes.

View full abstract

According to the trend of giving high quality to industrial machinery, designers are being required to improve the tonal impression of this machinery because of the social consensus on the preserving our living atmosphere, as well as cars and air conditioners. However, it is very difficult to evaluate unstable noise, e.g. impulsive or intermittent noise, due to the lack of sensory scalings, in contrast with the other machine's performance, which can be apparent by measuring its physical quantities. On this study, authors have researched on evaluation method composed by human auditory mechanism, and investigated the relation between tonal noisiness and firing-rates generated by gammatone filterbank and Meddis's hair-cell model for the operation noise of forklift truck. Then this evaluation results show that the correlation can be considered good enough to estimate noisiness of unsteady noise. This paper deals with the results of noisiness analysis and a numerical firing-rates simulation for predicting precise noisiness and controlling machinery noise.

View full abstract

In this paper, vibration signals are investigated. Vibration signal is a vibration we use with special purposes or intentions. Vibration signal can transmit information to person through the sense of touch. Vibrators of portable phones are one kind of examples. The purpose of this study is to research on human sensitivity by vibration frequency, vibration pattern and parts of body that receive signals, and to propose the most suitable vibration signal for information. At First, 5 trial vibration signals refering to clock alarm, oven, rice cooker, and public phone sounds were made to find out the most conscious vibration signal. These vibration signals were evaluated by using SD method and the factor analysis. And, the clock alarm type vibration signal was obtained to be the most conscious vibration among the vibrations adopted in this report. Then this signal was modified and compared with the original one. The suitable vibration signal for forefineer was found.

View full abstract

Although man has mainly acquired various information using vision and hearing, things other than required information will also be contained in the information acquired from them. Then, the method using the tactile sense as other means of communication of information is mentioned. Since the amount of information from which a tactile sense is obtained compared with vision and hearing is restricted, it is the optimum as a means to tell what to tell. The unevenness of various conditions which narrowed down the target to the tactile sense of the finger point, and changed the quality of the material, concavo- convex width, and concavo-convex height especially by this research based on the above thing is prepared, and the difference in how to feel vibration transmitted when it is traced at various speed is investigated.

View full abstract

Free vibration analysis was performed for a spinning disk/spindle system mounted on a flexible baseplate. A simplified model was presented considering the effects of the baseplate flexibility on a disk/spindle system, and the equations of motion were derived by the assumed mode method and Lagrange's equation. From the results of the free vibration analysis, the variations of the natural frequencies were investigated by changing rotating speed, baseplate thickness. They were attributed to the coupling between the flexible modes of the spinning disk/spindle system and the baseplate. This simplified model was used to predict the dynamic characteristics of a small size disk drive. The validity of the simplified model was verified by experiments and FE analysis.

View full abstract

A survey to reveal social structures to determine what kind of contents of public announcement systems are seen as noise by societies are conducted at neighboring areas whose characters are very different from each other : one is a boom town and the other is a old community. In conclusion, (1) Two types of common understandings of contents are exist : understanding as necessary information for the members of a community, and understanding as not necessary information for them. These common understandings make the contents whether noise or not. ; (2) In spite of necessities, scales of commonality of these understandings are variously from as small as small colony to as large as whole city, depending on contents. ; (3) In a boom town, there exist some residents who do not know the contents of public announcement or existence of the public announcement system.

View full abstract

Acoustically induced vibration in piping systems can cause severe failures -acoustic fatigue- of the piping structure in the process plant. To prevent the acoustic fatigue, the design criteria relating acoustic power level at noise sources to geometry parameter based on the ratio of the piping diameter to the thickness has been applied in some design specifications for the process plant of major oil companies. However, the evaluation method and the detailed mechanism of these phenomena are still under study. The numerical investigation using sound-structure interaction analysis has been done to give the dominant factors which cause the high stresses in the piping structure. The result shows that the coincidence of loading frequency and structural natural frequency plays an important role in acoustically induced vibrations. New geometry parameter representing the structural natural frequency was introduced as one of the reasonable approaches to make a screening diagram for prevention of acoustic fatigue for the plant design.

View full abstract

When a high speed train enter a tunnel, Low Frequency Noise problems occur around a tunnel entrance. This study measures low frequency noise at measurement points, which set up on meshed around a tunnel entrance, with an experimental set up at a laboratory. A sound pressure increases as the train gets closer to the tunnel entrance and decreases immediately after the entrance. Sound propagating velocity before the entrance is the same as the train speed. On the other hand, the sound propagates at the speed of sound after the entrance. Instant distribution diagrams of the sound pressure around the entrance show changes of the distribution visually when a train enters a tunnel.

View full abstract

The acoustic noise measurement standard for wind turbines provides to use a hard board placed on the ground to minimize the influence of different ground type as well as to reduce wind-induced noise. It also requires to report measurement uncertainty. Since ground surfaces of wind turbine site are believed to be variant from bare soil to grass covered with unevenness, it is necessary to acquire information concerning the ground type effects on measurements to improve measurement results. This report describes results of the tests on sound pressure level distributions due to obliquely incident sound over 1.5m diameter ground board on four different ground surfaces of cut-lawn, bare sandy soil and grown grasses. It was found that the board carefully placed on the bare soil surface avoiding making gap between the board and soil surfaces gives minimum spectrum error. Also effects of gap of the 1.0m diameter split board for acoustic measurements were examined.

View full abstract

For the purpose of reducing the cost, a control system for a truss structure with a simplified controller equipped with amplifying function alone is proposed. In order to realize a sensor in consideration of system stability, the sensor is provided with multiplication-addition capability and a distributed modal filter capable of isolating multiple vibration modes. Then, a control system is built up to amplify the sensor output through a power amplifier, by using a moment actuator which can exert actuation comparable to that of the velocity feedback for damping the system. Finally, the control system is incorporated to the truss structure and the vibration control effect through direct feedback is studied.

View full abstract

This paper describes the vibration simulation result of the washing machine. The washing machine mainly consists of the spinning basket, the tub which is connected by the shaft, and the four supporting rods from the tub. The spinning basket utilizes the liquid balancer to control the unbalance force. Therefore, one of the points for modeling is the construction method for the liquid balancer. This paper describes the modeling method and the simulation performance from the comparison with the experimental result. As the simulation result has a good agreement with the experimental result, it is possible to predict the transient procedure during the spinning course.

View full abstract

The small type high rotating speed water pumps which have inverter for rotating speed control have been served and are more quiet than those which install flow control valve. However, some annoying flow noise are closed up as the ordinal pumps noise have become quiet. This annoying noise source and generation mechanism have been experimentally studied. It was made clear by this study that the diffuser flow generated separated flow and radiated the annoying noise. The improved pump with smoothed diffuser decrease the annoying noise although noise spectra do not remarkably change. The analysis of sound quality with respect to this pumps noise have been examined and It has been recognized that "Loudness level" and "Sharpness" are remarkably decreased. It is concluded that the reduction of separated flow on the diffuser induced the decrease of "Loudness level" and "Sharpness" with respect to noise from the high speed pumps.

View full abstract

The flow induced noise from a simple cavity type muffler with pulsating flow and steady flow was studied. The main noises of flow induced noise were related to resonance of the cavity and the tail pipe of the muffler. The flow induced noise was extracted from the total noise radiating from the open end of the muffler by introducing a noise generation model. The sound power level of the flow induced noise in the case with pulsating flow was different from the case with steady flow, especially in the frequency range of the cavity resonance. Since the pressure fluctuation on surface solid wall is the main source of flow induced noise for a low Mach number flow, the pressure fluctuation spectrum was compared between the case with pulsating flow and steady flow.

View full abstract

In recent years, lighter and more compact car engines have been required to meet the requirements for performance, fuel consumption and collision safety. At the same time, demands for greater vehicle comfort have been increasing every year, making it necessary to reduce engine noise and vibration further. Against this backdrop, the vibration reduction technologies of the engine researched since before. But, the actual design is depend on an experience and trial and error. Because of this, there was no guarantee that the most suitable design within a given period of time. This paper describes the optimization calculation was applied to the development of the new engine.

View full abstract

The effects of the volute angle on the characteristics of the aerodynamics and noise of a dual-cascades centrifugal fan have been experimentally investigated. The experimental data of dual-cascade centrifugal fan compared to that of the fan was constructed by unique-cascade. Of the fan efficiency of design point, the former is higher than that of the latter by about 6%. In the region of high efficiency at which the efficiency is about maximum fan efficiency, the former is wider than latter. The fan noise at design point is same in the former and the latter. When the volute casing has an volute angle of 6°, the sound pressure level and the specific noise level of the fan are lowest and the fan efficiency is highest. The peak of sound pressure level of the rotating noise was not detected.

View full abstract

A measuring method for the transfer matrix parameters of acoustic systems by using 3-microphones is described in this report. The acoustic characteristics of engine intake systems are usually analyzed by the transfer matrix method. By using the 3-microphones method, the matrix parameters of unknown systems can be determined experimentally. The matrix parameters of the air cleaner were measured and used to predict the acoustic characteristics of the intake systems. The comparisons were made between predicting results using the matrix parameters and directly measuring results with mean flow. Agreement is fairly good and it suggests that this method can be used to evaluate the acoustic characteristics of intake systems with a low flow velocity.

View full abstract

A new resin recycling process has been put into commercial operation at two Nippon Steel's steel works in 2000. The new process is composed of the waste package plastics processing plant (WPP) that has been newly planted, and the existing coke batteries in that the processed resins are thermally cracked. The WPP is designed for removing the foreign matters form the contaminated waste plastics and making agglomerates of the waste resins. The crashers, sorting devices and compactor are arranged in the processing line so as the total plant functions effectively. The WPP properly processed a waste resin source from a city waste plant, which contains relatively large amounts of the foreign matters, during the test operation. A waste package resin source that is 97% pure resin is also processed very effectively. The WPP processed this waste resins at the designed production rate, 8 tons per hour.

View full abstract

Research and development of dismantling method of disposing composite waste such as household electrical appliances, in which the waste is not crashed, but heated to 600〜700℃ with no oxygen in its original form to melting and gasifying the plastic. This process makes the environmental load minimum : (a) Reduction in energy required for waste disposal. (b) Recovery of metals with a high level of purity. (c) Disposal of thermal insulation CFC as well as coolant CFC without additional costs. This research is on Recycling of Composite Material Waste by Thermal Elutriation System (TES), being conducted as one theme on commission from IMS Center.

View full abstract

We have already developed the electrostatic separator which utilizes characteristics of electrification caused by friction of plastics to recycle waste plastics. The electrostatic separator is composed of a separating part and a device of frictional electrification which stirs and equally electrifies plastics for a fixed time by batch process. Therefore, repeating the batch process with more stirrers are needed for continuous process. This report introduces an outline of a compact device of continuous frictional electrification which makes friction between plastics continuously and electrifies them. It also describes the examination performance of the electrostatic separator with the continuous frictional electrification

View full abstract

The authors have developed and commercialized the tribo-electrostatic separator for waste plastics into high-purity materials by type of plastic. This technology employs the frictional charged characteristics which is obtained when different types of plastic are rubbed together. And, it utilizes batch processing to frictional electrification in the standard type of this separator. Therefore, the successive batch processing is applied for continuous separation by plural frictional electrifiers. This report describes an outline of the tribo-electrostatic separator with the successive type batch processing and the results of a continuous separation test. It also describes some pre-treatment conditions which is necessary to obtain 99% or higher purity separation.

View full abstract

Of the 6 million tons of annual garbage (150 kilograms per capita of population per year) derived by commercial business in Japan, only 0.3 % is recycled. Garbage reduction and recycling are key priorities. The garbage drier dries by heating, and reduces the rate of moisture content from 80 % to about 10 %. The output can be processed into compost and recycled in the form of organic fertilizer. The drier can dry a 50-kilogram load of garbage in about seven hours, and is also compact and odor-free. The drier is now being field tested at four locations with a view to commercializing beginning in August 2001.

View full abstract

Based on the recycling Law for the vessel and packing which is enforced completely in the April last year, Nippon Steel Corporation started the waste-plastic recycling by the method of converting the chemical materials with coke oven, aiming toward the formation of resouce circulating type society. By utilizing the coke oven which is existing iron-manufacture process, the plastic waste can be recycled stably and continuously, and the recycling system which can contribute to a communitiy is realized. With this paper,as the technical feature is introduced, it reports concerning the start-up circumstance of the aparatus equipment which from last year was worked at the Nagoya Works.

View full abstract

Gasification melting system is necessary for recycling and volume reduction of solid waste. However, many explosions accidents are caused by combustible gases filled in shredding or gasification melting process from gas cylinder and spray-can mixed within bulky waste. In this experiment, inhibition of ignition of mixed fuel composed of C_3H_8, CO and H_2, N_2 or CO_2 as the inert gas is analyzed using a spark plug as the source of ignition. As a result, 1) according to the ignition limit calculated by Le Chatelier's formula, on some condition, there is a possibility of explosion accidents, 2) adiabatic flame temperature is constant at about 1500K under the condition of the ignition limit, and the ignition limit is valued by the product of organic radical and O containing radical, 3) Using the heat balance simulation, if DME or Cyclopentane is added to combustible gases, there is risk of explosion accidents.

View full abstract

In municipal solid waste treatment plant, it is effective to get rid of water from waste before heating process. We adopted a tubed steam waste dryer which heats waste indirectly by steam for a 10 t/d municipal solid waste treatment demonstration plant. Demonstration test was conducted over 100 days including 35days continuous operation. In this waste drying process, it is possible to utilize waste thermal energy of the plant by using steam. And also it is possible to exhaust harmless outlet gas of dryer because of low temperature heating. As a result of the test, high drying performance and superior harmless ability of the exhaust gas was verified and the system is proved to be an excellent waste drying method.

View full abstract

A 10 t/d demonstration plant of a pyrolysis gasification waste treatment system was constructed, and the demonstration test was conducted over 100 days by municipal solid waste. In the waste treatment system, the municipal solid waste are recycled as the clean fuel gas which is used in the gas engine power generation and the pyrolysis furnace. In the test period, the gas engine power generation experiments was conducted. The calorific values of the clean gas were 2500〜4000kJ/m3N, which were 6 to 10% of natural gas values (typically 4MJ/m3N). Although the low calorific values of the clean gas, the stable operation of the gas engine and the power generation was confirmed.

View full abstract

High Temperature Air Heater for Gasification and Ash-melting system was developed. This bayonett type heat exchanger with ceramics or heat-resistance cast alloy pipe elements is located at gas outlet of ash-melting furnace with exhaust gas temperature up to 1300℃. Supplied pre-heated air about 200〜250℃ will be heated to 700〜750℃ and can be used as heat source of superheating steam from 400℃ to 500℃ for high-efficiency power generation. Advantage of this "indirectly superheating system" is that it enables high-efficiency power generation in refuse incinerator without hot corrosion of superheater materials. In this report, results of heat and corrosion resistance test of the pipe element materials on the demonstration plant and summary of feasibility study on Gasification and Ash-melting system of municipal solid wastes with high-efficiency power generation system according the High Temperature Air Heater will be shown.

View full abstract

Recently, various kinds of new refuse disposal technologies are proposed and developed. In this study, we estimate the life cycle energy and emissions for the new refuse disposal technology and intend to operate the evaluation of the environmental load with the use of LCA method. We use the Environmental Load Point (ELP) for index. Especially, we focus on the effect of dioxin discharge from waste disposal and treatment facility. And we also investigate the relation between the effect of decrease of environmental load and the cost for the technology. For the evaluation, we assume the case of biogas and plastic liquefaction technologies.

View full abstract

In order to develop engine generators for waste gasification and power generation systems, combustion characteristics of low-BTU gas (about 1000kcal/Nm3) were experimentally investigated Two kinds of simulated low-BTU gas obtained from one-step high temperature gasification (hydrogen rich) and two-step pyrolysis/reforming gasification (methane rich) as well as natural gas were tested in a small-scale spark ignition engine. Compared with natural gas driven, the hydrogen rich low-BTU gas driven engine showed similar thermal efficiency while significantly lower NOx and hydrocarbon emissions and wider equivalence ratio range for stable engine operation. On the other hand, the methane rich low-BTU gas showed narrower equivalence ratio range for stable engine operation. From these results, it was shown that engine performance depends on combustion speed rather than heating value of the fuel gas. From the point of better engine performance, hydrogen rich fuel gas is desirable.

View full abstract