检索结果-南通市图书馆

Recent advances in ultrasonic-assisted machining for the fabrication of micro/nano-textured surfaces

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2017年第1期12卷 33-45页

作者： Shaolin XU Tsunemoto KURIYAGAWA Keita shimada Masayoshi MIZUTANI Division of Biomechanical Engineering Graduate School of BiomedicalEngineering Tohoku University Sendai 980-8579 Japan Department of Mechanical Systems Engineering Graduate School ofEngineering Tohoku University Sendai 980-8579 Japan

In this paper, the state of art of ultrasonic- assisted machining technologies used for fabrication of micro/nano-textured surfaces is reviewed. Diamond machining is the most widely used method in industry for manufacturing precision parts. For fabrication of fine structures on surfaces, conventional diamond machining methods are competitive by considering the precision of structures, but have limitations at machinable structures and machining efficiency, which have been proved to be partly solved by the integration of ultrasonic vibration motion. In this paper, existing ultrasonic-assisted machin- ing methods for fabricating fine surface structures are reviewed and classified, and a rotary ultrasonic texturing （RUT） technology is mainly introduced by presenting the construction of vibration spindles, the texturing principles, and the applications of textured surfaces. Some new ideas and experimental results are presented. Finally, the challenges in using the RUT method to fabricate micro/ nano-textured surfaces are discussed with respect to texturing strategies, machinable structures, and tool wear.

关键词： ultrasonic-assisted machining textured sur-face micro/nano-structures functional performance

An Example of Canal Formation in a Thick Cloud Induced by Massive Seeding Using Liquid Carbon Dioxide

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Meteorological Research 2015年第4期29卷 682-690页

作者： KIKURO Tomine MASAKI shimada KENJI Wakimizu KOJI Nishiyama Department of Earth and Ocean Sciences National Defense Academy Faculty of Agriculture Kyushu University Hakozaki Faculty of Engineering Kyushu University Motooka

The purpose of this experiment is to show that massive cloud seeding is effective in mitigating the damage caused by heavy snowfall. In order to show its effect, we attempted to form a canal in a thick convective cloud by massive seeding, and left the parts that were not influenced by the seeding as a reference to show that the canal was formed by the massive seeding only. The seeding was carried out by using an aircraft. The seeding rate and air speed of the aircraft were 35 g s-1 and 115 m s 1, respectively. The flight course for seeding was selected to be parallel to the wind direction to ensure that the dispersed liquid carbon dioxide did not influence both sides of the course. The results show that a part of the radar echo observed from onboard beneath the seeding track was weakened and divided the radar echo into two parts 20 minutes after the cloud top and the bottom were seeded, and distribution of rainfall rate on the ground from the target cloud was confirmed to be divided into two parts 24 minutes after the seeding. The target cloud was torn along the seeding track, and we could see the sea surface through the break in the cloud. Canal formation occurred in the cloud along the seeding track. Clouds and snowfall were left on both sides of the canal. The results show that supercooled liquid cloud particles along the seeding track evaporated to form larger precipitable particles which grew and fell rapidly.

关键词： heavy snowfall weather modification aircraft artificial cloud seeding

Long Gap Discharge Guiding Experiments Using Strongly and Weakly Ionized Plasma Channels for Laser Triggered Lightning

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2007年第6期9卷 740-742页

作者： Y.shimada M.YAMAURA C.YAMANAKA Institute for Laser Technology OsakaJapan

A study to generate longer plasma channel was conucted to improve probability of triggered lightning. To generate the long laser plasma channel, a strongly and a weakly ionized plasma channels were used in series, a scheme called hybrid method. The strongly and the weakly ionized plasma channels were used for triggering an electrical leader and guiding the leader. The electrical leader propagated through the weakly ionized plasma. Then main discharge occurred between the electrodes. It is found that the streamer was accelerated with both the increase in the plasma density and the increase in an ambient electric field close to the plane electrode.

关键词： laser plasma channel lightning velocity of streamer

The Fundamentals Underlying the Computations of Acceleration for General Dynamic Applications:Issues and Noteworthy Perspectives

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2015年第2期104卷 133-158页

作者： M.shimada A.Hoitink K.K.Tamma Department of Mechanical Engineering University of Minnesota111 Church St.SEMinneapolisMN55455USA.

To-date,with the exception of the Newmark method and the midpoint rule,most computational algorithms under the umbrella of LMS methods,which are predominantly employed in research and commercial software fail to properly evaluate acceleration computations accurately for conducting the numerical dynamic ***,this is not trivial and a sound theoretical basis of the fundamental underlying issues is described in *** this paper,we provide a resolution and point-out several noteworthy perspectives to address the proper evaluation of acceleration computations for structural dynamics applications with focus on the class of LMS methods as an illustration.

关键词： acceleration trivial illustration

Gas Absorption by Wavy Falling Liquid Film Formed on Inner Surface of Vertical lubes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2003年第1期12卷 57-61页

作者： Akio Miyara Tomoki Yamamoto Toru Iemura Takashi shimada Department of Mechanical Engineering Saga UniversityGraduate School of Science and Engineering Saga UniversityGraduate School of Science and Engineering Saga UniversityGraduate School of Science and Engineering Saga University 1 Honjomachi Saga-shi 840-8502 Japan 1 Honjomachi Saga-shi 840-8502 Japan1 Honjomachi Saga-shi 840-8502 Japan1 Honjomachi Saga-shi 840-8502 Japan

An experimental study on gas absorption into falling liquid film formed on inner surface of vertical tubes has been carried out in order to clarify fundamental characteristics of the gas absorption and enhancement by surface waves. The water supplied into the test tubes is periodically disturbed by fluctuating a silicon tube before the test section with a speaker and the wavy films absorb the oxygen filled in the tubes. Imposing the periodic disturbance enhances the gas absorption and the enhancement has a maximum at around 20-30 Hz, where the gas absorption is 20-30% higher. Mass transfer coefficients obtained with five tubes agree well with those obtained with single tube. Two-dimensional numerical simulations have also been conducted for gas absorption by wavy film and the enhancement mechanism of the gas absorption is discussed.

关键词： falling liquid film gas absorption surface wave vertical tube mass transfer enhancement.

ILES of an array of three subsonic counter-flow jets issuing from a wing leading edge exposed to hypersonic aerodynamic heating

在线全文

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2020年第1期2卷 236-249页

作者： Tomonori shimada Taku Ohwada Department of Aeronautics and Astronautics Graduate School of EngineeringKyoto UniversityKyoto 615-8530Japan

The flow of an active thermal protection system exploiting subsonic counter-flow jets for wing leading edges of hypersonic vehicles is numerically studied on the basis of the three dimensional Navier-Stokes *** coolant air issuing from around the stagnation point as an array of three jets spreads over both the upper and the lower sides of the cylinder surface and about 40~60%cooling effectiveness is achieved in the range up to 5 degrees angle of attack despite the occurrence of various three-dimensional fluid-dynamic *** numerical scheme is second order accurate but simple inclusion of high order polynomial approximation in the reconstruction enables the capturing of finer structure of the flow field.

关键词： Subsonic jet Counter-flow Aerodynamic heating TPS Rayleigh-Taylor Kelvin-Helmholtz Near-wall streaks

Framework for automatic generation of facades on free-form surfaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2017年第3期6卷 273-289页

作者： Diego Andrade Mikako Harada Kenji shimada Mechanical Engineering Department Carnegie Mellon University Pittsburgh PA 15213 United States Autodesk Manchester NH 03101 United States

New design tools have created a growing interest for presenting complex geometries and patterns. The need to form curved geometries of facades, without incurring high construction costs and time increases, presents one of the most complex design challenges for any project. In this paper, we present and demonstrate a new computational framework for the creation of patterns on top of facades, via cladding of panels and honeycomb structures. The tool describes a given region on a base model; dealing particularly with location, size and orientation of general geometric features on the surface of such model. The user inputs curves that manifest the desired user＇s intention for the panels and a set of seed features that correspond to the initial boundary conditions of a Riemannian metric tensor field. The system interpolates the tensors defined by input features and input curves by solving a Laplace-Beltrami partial differential equation over the entire domain. We show a fast clustering and search operations for correct panel utilization based on size quantization as design variable and implemented via Voronoi segmentation. We present honeycomb structures that can be retrieved from the fundamental mesh producing another option for facade creation and ideation. The system connects to a geometric modeling kernel of a commercial CAD package; the system places features on top of the base model facade using boolean operations from the core geometdc engine via its programming interface calls. With this computational tool, thousands of dad panels can be visualized and developed within minutes.

关键词： Computer graphics Eltipsoidal packing Supporting structures Architectural geometry Computationat geometry Generative designalgorithms

Observations and modeling of the ice-ocean conditions in the coastal Chukchi and Beaufort Seas

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2008年第3期27卷 79-87页

作者： JIN Meibing WANG Jia MIZOBATA Kohei HU Haoguo shimada Koji International Arctic Research Center University of Alaska Fairbanks AK 99775-7340 USA NOAA Great Lakes Environmental Research Laboratory Ann Arbor MI 48105 USA Tokyo University of Marine Science and Technology 4-5-7 Kounan Minato-ku Tokyo 108-8477 Japan Cooperative Institute for Limnology and Ecosystems Research School of Natural Resources and Environment University of MichiganAnn Arbor MI USA

The Chukchi and Beaufort Seas include several important hydrological features： inflow of the Pacific water, Alaska coast current （ ACC ）, the seasonal to perennial sea ice cover, and landfast ice ＇along the Alaskan coast. The dynamics of this coupled ice-ocean system is important for both regional scale oceanography and large-scale global climate change research. A mumber of moorings were deployed in the area by JAMSTEC since 1992, and the data revealed highly variable characteristics of the hydrological environment. A regional high-resolution coupled ice-ocean model of the Chukchi and Beaufort Seas was established to simulate the ice-ocean environment and unique seasonal landfast ice in the coastal Beaufort Sea. The model results reproduced the Beaufort gyre and the ACC. The depthaveraged annual mean ocean currents along the Beaufort Sea coast and shelf hreak compared well with data from four moored ADCPs, but the simulated velocity had smaller standard deviations, which indicate small-scale eddies were frequent in the region. The model resuits captured the sea,real variations of sea ice area as compared with remote sensing data, and the simulated sea ice velocity showed an ahnost stationary area along the Beaufort Sea coast that was similar to the observed landfast ice extent. It is the combined effects of the weak oceanic current near the coast, a prevailing wind with an onshore component, the opposite direction of the ocean current, and the blocking hy the coastline that make the Beaufort Sea coastal areas prone to the formation of landfast ice.

关键词： circulation sea ice fast ice Beaufort Sea coupled ice-ocean model

Deep learning for three-dimensional segmentation of electron microscopy images of complex ceramic materials

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2024年第1期10卷 2758-2767页

作者： Yu Hirabayashi Haruka Iga Hiroki Ogawa Shinnosuke Tokuta Yusuke shimada Akiyasu Yamamoto Department of Applied Physics Tokyo University of Agriculture and TechnologyKoganeiTokyo 184-8588Japan Department of Advanced Materials Science and Engineering Kyushu UniversityKasugaFukuoka 816-8580Japan JST-CREST KawaguchiSaitama 332-0012Japan

The microstructure is a critical factor governing the functionality of ceramic ***,microstructural analysis of electron microscopy images of polycrystalline ceramics,which are geometrically complex and composed of countless crystal grains with porosity and secondary phases,has generally been performed manually by human *** pixel-based analysis(semantic segmentation)with high accuracy is a simple but critical step for quantifying *** this study,we apply neural network-based semantic segmentation to secondary electron images of polycrystalline ceramics obtained by three-dimensional(3D)*** deeplearning-based models(e.g.,fully convolutional network and U-Net)by employing a dataset based on a 3D scanning electron microscopy with a focused ion beam is found to be able to recognize defect structures characteristic of polycrystalline materials in some cases due to artifacts in electron microscopy *** to the training images with improved depth accuracy,the accuracy evaluation function,intersection over union(IoU)values,reaches 94.6%for *** IoU values are among the highest for complex ceramics,where the 3D spatial distribution of phases is difficult to locate from a 2D ***,we employ the learned model to successfully reconstruct a 3D microstructure consisting of giga-scale voxel data in a few *** resolution of a single voxel is 20 nm,which is higher than that obtained using a typical X-ray computed *** results suggest that deep learning with datasets that learn depth information is essential in 3D microstructural quantifying polycrystalline ceramic ***,developing improved segmentation models and datasets will pave the way for data assimilation into operando analysis and numerical simulations of in situ microstructures obtained experimentally and for application to process informatics.

关键词： ceramic ceramics complex