Search

Longitudinal vortex generated around automobiles and airplanes is reproduced by a delta wing with attack angle of 15°, which was merged in the uniform flow at 10 m/s. The paper aims to clarify the sound source of the longitudinal vortex system. The beamforming technique was applied to identify the sound sources of the vortex system in the JAXA (Japan Aerospace Exploration Agency) wind tunnel. To verify the simulation model used, aerodynamic sound in the far field was compared with measured one. Estimated sound agrees quite well with measured one. To clarify aerodynamic sound generation mechanism, sound source distribution and vortex structure were numerically investigated. As a result, following findings were obtained. (1) Dominant sound source was experimentally observed by beamforming technique at the apex of the longitudinal vortex system. (2) Numerical analysis clarified sound source distributions of derivatives of surface pressure fluctuations, which were caused by the strongest unsteady motions of the vortices at the apex of the vortex system.

The paper describes the effects of heat transfer enhancement and gas-flow characteristics by wing-type-vortex-generators inside a rectangular gas-flow duct of a plate-fin structure exhaust gas recirculation (EGR) cooler used in a cooled-EGR system. The analyses are conducted using computational fluid dynamics (CFD). The numerical modelling is designed as a gas-flow rectangular duct of an EGR cooler using two fluids with high temperature gas and coolant water whose flow directions are opposite. The gas-flow duct used to separate two fluids is assembled with a stainless steel material. The inlet temperature and velocity of gas flowed inside gas-flow duct are 400°C and 30 m/s, respectively. Coolant water is flowed into two ducts on both a top and a bottom surface of the gas-flow duct, and the inlet temperature and velocity is 80°C and 0.6 m/s, respectively. Wing-type-vortex-generators are designed to achieve good cooling performance and low pressure drop and positioned at the center of the gas-flow duct with angle of inclination from 30 to 150 degrees at every 15 degrees. The temperature distributions and velocity vectors gained from numerical results were compared, and discussed. As a result, it is found that the vortices guided in the proximity of heat transfer surfaces play an important role in the heat transfer enhancement and low pressure drop. The collapse of the vortices is caused by complicated flow induced in the corner constituted by two surfaces inside gas-flow duct.

The present paper describes control of wingtip vortices generated by vertical type wind turbine. The wind turbine consists of three circular cylinders. Each cylinder rotates on its own vertical axis and moves in orbit. It is known that wingtip vortices give rise to decrease of power generation performance as well as aerodynamic noise. Therefore, the goal of the study is to control wingtip vortices and to improve power generation performance. Numerical study was conducted for 14 models to find out control factors to suppress wingtip vortices. Numerical simulation visualized wingtips by streamlines as well as pressure distribution on the circular cylinder for evaluating Magnus effect. As a result, the following findings were obtained: 1) Installation of fully covered protection plates at both ends of the circular cylinder blades is greatly effective to suppress the wingtip vortices. 2) Curved wings attached to each cylinder are more effective to enhance power generation efficiency than flat ones, due to great increase in Magnus effect caused by large pressure difference on both sides of the curved wing. The power efficiency of the optimized model was improved up to 2.8%, which means 11 times that of the original model.

To elucidate a biological role of the methylated mannose residues found in N-glycans of terrestrial worm Enchytraeus japonensis, we first synthesized 3-O-methyl mannose- and 4-O-methyl mannose-derivatives and immobilized them to Sepharose 4B beads in order to isolate the sugar-binding protein. When whole protein extracts from the worms was applied to a series of the columns immobilized with the modified and unmodified mannose-derivatives, respectively, a protein with a molecular weight of 25,000 was isolated by 4-O-methyl mannose-immobilized column chromatography, and termed as a methylated mannose-binding protein (mMBP). mMBP bound weakly to a mannose-immobilized column and moderately to a 3-O-methyl mannose-immobilized column. The N-terminal amino acid sequences of mMBP and its endoprotease-digested peptides were determined. Using the degenerate first primers synthesized based on the primary sequence, a genomic DNA fragment was isolated. Then, the second primers were synthesized based on the genomic DNA fragment, and with use of them two cDNA fragments were obtained by the 3'- and 5'-RACE methods. Finally, the third primers were synthesized based on the sequences of the two cDNA fragments and one genomic DNA fragment, and with use of them a full-length cDNA of mMBP was isolated and shown to comprise a putative 633 bp open reading frame encoding 210 amino acid residues. BLAST analysis revealed that mMBP has identities by 26 ~ 55% to several proteins including the regeneration-upregulated protein 3 from the same species. Whether mMBP is involved in the regeneration of the worm is under investigation.

Decreasing the death toll of pedestrians in traffic accidents is one of the most urgent tasks to be solved all over the world. This paper describes the prediction of pedestrian injuries for the TRL legform impactor using MATLAB. The TRL legform impactor consists of three parts: a femur, a tibia, and a ligament connecting them. The impactor was physically modelled with springs, dampers and two masses as a dynamic model. The impactor behaves in a translational and rotational motion during the collision with a vehicle. The behavior of the impactor during the crash event was captured by a high speed camera and is regarded as the four-degree-of-freedom system in terms of translational and rotational motions. Pedestrian injuries are evaluated by three physical quantities indexes: the acceleration of the tibia, both the displacement and the bending angle between the femur and the tibia. The physical model for the impactor was expressed mathematically by differential equations. In the case of modelling, the ligament connecting both the femur and the tibia in particular plays an important role. Shear forces were applied to the ligament in translational motions and the bending moments in rotational motion. Differential equations were expressed in the form of a state equation and an output equation by MATLAB. Numerical solutions were obtained by a block diagram with Simulink. As a result, it was found that the predicted injuries agree quite well with their experimented data in terms of acceleration, displacement, and the bending angle mentioned above.

While driving a car at high speed cruising, the mirror surface of side-view mirrors happens to vibrate. The vibration often leads to image blurs of objects reflected in the mirror. Once the phenomena happen, drivers cannot clearly identify the approaching vehicles from the rear. The paper aims to clarify the vibration modes of side-view mirror experimentally and to capture forces on the mirror surface induced by separating vortices around the mirror numerically. Experimental study clarified two findings. One is that the mirror has the primary natural frequencies of 25, 30 and 33 Hz. The other is that vibrations of the mirror increase in proportion to flow velocity and their frequencies have peak values at 120 and 140 km/h. The frequencies of the mirror vibration coincide completely with the primary natural frequencies. In order to capture the external forces vibrating the mirror surface, numerical study was performed by unsteady air-flow analyses. Relationships between flow velocity fluctuations close to the mirror surface and pressure fluctuations on the mirror surface were investigated. It was found that the two power spectra have peak values at the same frequency of 24.4 Hz at 120 km/h. This shows that flow velocity fluctuations with the frequency of 24.4 Hz affect directly pressure fluctuations on the mirror surface. Numerical analyses clarify that the frequencies of shedding vortices are 24.4 Hz at 120 km/h and 28.3 Hz at 140 km/h. The frequencies of mirror vibration are very close to those of flow fluctuations. This shows that the frequencies of the mirror vibration have much to do with the frequencies of the forces induced aerodynamically by vortex shedding. Therefore it follows that image blurs at high speed cruising are caused by resonance phenomena that the mirror surface resonates with the frequencies of shedding vortices around the mirror.

Flow around the front pillar of an automobile is typical of a flow field with separated and reattached flow by a vortex system. It is known that the vortex system causes the greatest aerodynamic sound around a vehicle. The objective of the present study is to clarify the relationship between vortical structures and aerodynamic sound by the vortex system generated around the front pillar. The vortex system consists of the longitudinal and the transverse system. The characteristics of the longitudinal vortex system were investigated in comparison with the transverse one. Two vortex systems were reproduced by three-dimensional delta wings. The flow visualization experiment and the computational fluid dynamics (CFD) captured well the characteristics of the flow structure of the two vortex systems. These results showed that the longitudinal with the rotating axis along mean flow direction had cone-shaped configuration whereas the transverse with the rotating axis vertical to mean flow direction had elliptic one. Increasing the tip angles of the wings from 40 to 140 degrees, there first exists the longitudinal vortex system less than 110 degrees, with the transition region ranging from 110 to 120 degrees, and finally over 120 degrees the transverse appears. The characteristics of aerodynamic sound radiated from the two vortex systems were investigated in low Mach numbers, high Reynolds number turbulent flows in the lownoise wind tunnel. As a result, it was found that the aerodynamic sound radiated from both the longitudinal and the transverse vortex system was proportional to the fifth from sixth power of mean flow velocity, and that the longitudinal vortex generated the aerodynamic sound larger than the transverse.

The purpose of the paper is to clarify the mechanism of generation and collapse of a longitudinal vortex system induced around the leading edge of a delta wing. CFD captured well characteristics of flow structure of the vortex system. It is found that the vortex system has a cone-shaped configuration, and both rotational velocity and vorticity have their largest values at the tip of the vortex and reduce downstream along the vortical axis. This resulted in inducing the largest negative pressure at the tip of the delta wing surface. The collapse of the vortex system was also studied. The system can still remain until the tip angle of 110 degrees. However, between 110 degrees and 120 degrees, the system becomes unstable. Over 120 degrees, the characteristics of the vortex are considered to have converted from the longitudinal vortex to the transverse one.

In several organisms that form fruit bodies, the synthesis of lectins is developmentally regulated. Aleuria aurantia is an ascomycete that forms a fruit body known as orange peel mushroom. To find whether the mycelia of this organism synthesize a lectin, mycelial isolates were obtained from a wild fruit body by spore germination and regeneration from a fragment of the fruit body. The isolates were identified as A. aurantia by analysis of their DNA. The mycelial isolates synthesized a lectin with the same properties as those of fruit-body lectin in terms of subunit molecular mass, immunochemical reactivity, binding specificity for L-fucose, and N-terminal amino acid sequence. Vegetatively growing mycelia synthesized as much lectin as the fruit body, so such synthesis was not developmentally regulated, unlike some other organisms that form fruit bodies.

The tracheobronchial structures were evaluated by multidetector-row computed tomography (MDCT), which provided imaging information for one-lung anesthesia during thoracic surgery. The subjects consisted of 100 patients. Three-dimensional (3D) images of the tracheobronchial structures and the bronchial tubes were created. Individual differences were found in the tracheobronchial structures in 100 patients. The length and the diameter of the right main bronchus were measured with 3D images and were not related to the patient’s physical appearance, such as body height. Problematic intubation cases included a short right main bronchus

In order to help to reduce CO2 and to protect the environment, vehicle body engineers are focusing on reducing vehicle weight. For this purpose, CAE tools are widely used. During a recent new car development, Mazda found that the energy gained from crash computer-aided engineering (CAE), which is currently insufficiently used, could be an excellent index for a crash safety strategy and weight reduction [1].

Many studies have reported tree growth reduction in forests with pedestrian trampling, implying a reduction of tree transpiration in such forests. We undertook observations of tree transpiration based on the heat-pulse method in a forest (Lithocarpus edulis) with pedestrian trampling. We prepared trampled and control plots in the forest. Tree transpiration in the trampled plot was reduced compared to that in the control plot after precipitation with a small-precipitation period preceding this. No difference was observed between plots in the small-precipitation period itself; during which tree transpiration was limited in both plots. After the period, tree transpiration recovery was not as complete in the trampled plot as in the control plot. This was caused by incomplete soil matric potential recovery at 20 cm and deeper in the trampled plot due to a lower infiltration rate. We believe this study is the first to report reduction of tree transpiration in a forest with pedestrian trampling.

The behavior of dissolved and particulate components of stream nitrogen (N) and phosphorus (P) were measured for 2 years in a small mountainous watershed covered primarily with a plantation forest of Japanese cypress (Chamaecyparis obtusa). The load of dissolved N and P bore a consistent relationship to discharge while the load of particulate N and P varied by up to two orders of magnitude at a given discharge level. Most N was exported in a dissolved form (DN) while most P was exported in a particulate form (PP), which bears similarity to loads from agricultural watersheds. Owing to the different behaviors of DN and PP, changes in the total nitrogen (TN) load were primarily attributed to variations in discharge unlike changes in the total phosphorus (TP) load. High flow conditions, resulting from heavy rainfall, displayed PP release significantly larger than expected. The TP load in high flow conditions was severely underestimated using a regression equation expressed as a function of discharge, which was based on the weekly sampling data biased toward low flow conditions. In addition, the TN load during peak discharges in heavy rain events was underestimated by the regression equation because of unpredictable increases in the particulate component. Our study shows that the particulate component ratio determines whether discharge can explain changes in load regardless of chemical species. The results suggest that plantation forests in rainy regions can be a diffuse source of particulate nutrients depending on soil surface conditions.

The extractability of dioxins from suspended substances (SS) in distributed water was evaluated. Dioxins adsorbed on the collected SS were extracted by pressurized liquid extraction with various solvents. High-polarity solvents (acetone, alcohols) extracted considerably higher amounts of some lower-chlorinated dibenzo-p-dioxins (LoCDDs) than did low-polarity solvents (dichloromethane, toluene), whereas the extracted amounts of higher-chlorinated dibenzo-p-dioxins (HiCDDs) were roughly the same, regardless of the solvent. The extractability of the LoCDDs depended on the isomer. Daily variations in quantities for PCDDs, organic matter (OM), and iron in the SS were examined, and the results suggested that in the SS, LoCDDs and HiCDDs were associated, respectively, with raw water-derived organic matter and microparticles sequestered in iron oxy(hydr)oxide floc. It was also suggested that the low extractability of certain congeners was not attributable to the enormously coexisting ferric compounds but was prob...

The effects of rainfall conditions and the morphological characteristics of leaves on the moisture dynamics of litter layers were investigated. Maximum water storage capacity and interception storage capacity under various rainfall conditions were evaluated for two contrasting litter types: a needle-leaf type, represented by Cryptomeria japonica leaves; and a broad-leaf type, represented by Lithocarpus edulis leaves. An artificial rainfall simulator was applied to measure each litter type’s interception storage capacity under various rainfall intensities. Our results indicated that (1) the maximum water storage capacity of each litter layer was proportional to the litter mass (kg/m 2 ) regardless of layer thickness; (2) the litter interception storage capacity increased with rainfall intensity in the range of realistic rainfall conditions (under 50 mm/h); (3) the broad-leaf litter of L. edulis intercepted more rainwater than the needle-leaf litter of C. japonica; and (4) the rainwater moved laterally in the litter layer of L. edulis whereas it moved directly down in the litter layer of C. japonica. These results show that not only the litter mass but also the rainfall conditions and leaf shapes are important in evaluating the moisture dynamics of litter layers. Copyright  2004 John Wiley & Sons, Ltd.

Mossbauer absorber experiments on 57 Fe deposited on CZ-Si are performed to study the lattice sites and the electronic states of Fe atoms in Si at 1273 K. Substitutional Fe atoms and Fe clusters are directly observed in Si at 1273 K. The Fe atoms are found to distribute dominantly in a region down to about 500 nm from the surface by SIMS measurements performed after the whole Mossbauer experiments at high temperatures. The 57 Fe diffusivity in Si at 1273 K can be estimated to be about 2×10 −20 m 2 /s from the depth profile of the Fe atoms.

広島県江田島流域での山火事後約20年間における基底流出量の変化について検討した.解析では,対照流域の日流出量が1.0mm/d未満であるときの山火事跡流域の流出量(低流出量とした)に着目し,季節別および低流出量の大きさ別にその変化を調べた.その結果,山火事後約20年間において,低流出量は季節や流出量の大小を問わず減少していた.ただし,その減少パターンは季節降水量により異なった.通常の降水量がある場合,低流出量の減少量は,春夏に最大となり,それに次いで夏秋,冬の順であった.また,小さい低流出量ほど減少量は少なかった.異常少雨の場合,夏秋における低流出量の減少量は多く,特に小さい低流出量において減少量は極めて多かった.これらの結果から,(1)植生回復に伴う蒸発散の増加が低流出の減少をもたらすこと,(2)蒸発散の増加により冬に土壌水分不足が生じること,(3)小さい流出量ほど蒸発散の影響を受けにくいこと,および(4)低流出量の大きさによって流出水の形成過程や流出経路が異なることが示唆された.

The disintegration of chloroplasts during zygote maturation in Closterium ehrenbergii Meneghini ex Ralfs was examined mainly by electron microscopy. The young zygotes each contained four chloroplasts derived from the plus and the minus gametes. Ca. 7 d after gamete union, two of the four chloroplasts within a zygote began to disintegrate. The disintegrating chloroplasts turned yellow and rapidly lost starch grains. Subsequently, they became fragmented, each fragment having many plastoglobuli and residual thylakoid membranes. At this stage, vacuolar structures of various sizes in section appeared within the cytoplasm. Each of them was limited by a single membrane and contained small vesicles and electron‐translucent materials. The chloroplast fragments seemed to be separated from the ground cytoplasm by their fusion with the vacuolar structures, and they were broken down into aggregations of plastoglobuli and residual membrane pieces by 2 wk after plasmogamy. Dictyosomes sometimes lay close to the vacuolar...