检索结果-南通市图书馆

The vibroacoustic response and sound absorption performance of multilayer, microperforated rib-stiffened plates

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第5期33卷 926-941页

作者： Haian Zhou Xiaoming Wang Huayong wu Jianbing Meng School of Mechanical Engineering Shandong University of Technology School of Mechanical Engineering Dalian University of Technology School of Aeronautics Shandong Jiaotong University

The vibroacoustic response and sound absorption performance of a structure composed of multilayer plates and one rigid back wall are theoretically analyzed. In this structure, all plates are two-dimensional, microperforated, and periodically rib-stiffened. To investigate such a structural system, semianalytical models of one-layer and multilayer plate structures considering the vibration effects are first developed. Then approaches of the space harmonic method and Fourier transforms are applied to a one-layer plate, and finally the cascade connection method is utilized for a multilayer plate structure. Based on fundamental acoustic formulas, the vibroacoustic responses of microperforated stiffened plates are expressed as functions of a series of harmonic amplitudes of plate displacement, which are then solved by employing the numerical truncation method. Applying the inverse Fourier transform, wave propagation, and linear addition properties, the equations of the sound pressures and absorption coefficients for the one-layer and multilayer stiffened plates in physical space are finally derived. Using numerical examples, the effects of the most important physical parameters-for example, the perforation ratio of the plate, sound incident angles, and periodical rib spacing-on sound absorption performance are examined. Numerical results indicate that the sound absorption performance of the studied structure is effectively enhanced by the flexural vibration of the plate in water. Finally, the proposed approaches are validated by comparing the results of stiffened plates of the present work with solutions from previous studies.

关键词： Sound absorption Multilayer Microperforated Rib-stiffened Flexural Vibration

Submarine slide evidence for late Miocene strike-slip reversal of the Red River Fault

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2016年第11期59卷 2231-2239页

作者： WANG DaWei wu ShiGuo LI ChunFeng YAO GenShun Institute of Deep-sea Science and Engineering Chinese Academy of Sciences Sanya 572000 China Ocean College Zhejiang University Zhoushan 310013 China PetroChina Hangzhou Institute of Geology Hangzhou 310023 China

During the late Miocene(~5.5 Ma), a large-scale submarine slide with an area of approximately 18000 km^2 and a maximum thickness of 930 m formed in the deep-water region of the Qiongdongnan Basin. The large-scale submarine slide has obvious features in seismic profile, with normal faults in the proximal region, escarpments at the lateral boundary, and a pronounced shear surface at the base. The internal seismic reflections are chaotic and enclosed by parallel and sub-parallel seismic *** main direction of sediment transport was from south to north and the main sediment source was the southern region of the Qiongdongnan Basin, which is located in the east of the Indo-China Peninsula and the north of the Guangle uplift. In this region,late Miocene strike-slip reversal of the Red River Fault, uplift and increased erosion of the Indo-China Peninsula, and an abrupt rise in the rate of deposition in the western part of the South China Sea provided the basic conditions and triggering mechanism for the large-scale submarine slide. The discovery of the large-scale submarine slide provides sedimentological evidence for the tectonic event of late Miocene strike-slip reversal of the Red River Fault. It can also be inferred that the greatest tectonic activity during the process of the Red River Fault reversal occurred at ~5.5 Ma from the age of top surface of the submarine slide.

关键词： Red River Fault Qiongdongnan Basin Deep-water Submarine slide Seismic reflection character

A Posture Recognition System for Rat Cyborg Automated Navigation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2018年第4期27卷 687-693页

作者： ZHANG Zhenchuan YANG Yingchun wu Zhaohui MA Qian College of Computer Science and Technology Zhejiang University College of Computer Science and Technology Qiushi Academy for Advanced Studies Zhejiang University

Rat cyborg is a rat which can receive cerebral commands and act as human wants. The navigation task is a widely used scenario in which the rat cyborg is required to walk along a specified path according to commands. Mostly the commands are given by human operators, but there’s a need for automatic control which is quite challenging since several modules need to be elaborately combined together to work as a whole, among which the monitoring system and the commands model are two major components. Previously, few attempts were made for behavior monitoring of rat cyborg. Existing works often implement an over-simple rat information extractor which is capable of giving only a few parameters of the rat cyborg, which greatly limited the performance of their automatic control accuracy. In response to this requirement,we develop a monitoring system that is capable of giving detailed motion parameters and accurate body postures of the rat cyborg. We explore the possibility of recognizing rat postures using shape information, which is described by the powerful Zernike moments. We propose several simple shape descriptors which are fast to compute and achieve acceptable performance.

关键词： Rat cyborg Posture recognition Rat posture

Into Africa via docked India: a fossil climbing perch from the Oligocene of Tibet helps solve the anabantid biogeographical puzzle

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science Bulletin 2019年第7期64卷 455-463页

作者： Feixiang wu Dekui He Gengyu Fang Tao Deng Key Laboratory of Vertebrate Evolution and Human Origins Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Center for Excellence in Life and Paleoenvironment Chinese Academy of Sciences Key Laboratory of Aquatic Biodiversity and Conservation Institute of Hydrobiology Chinese Academy of Sciences College of Earth Sciences University of Chinese Academy of Sciences

The northward drift of the Indian Plate and its collision with Eurasia have profoundly impacted the evolutionary history of the terrestrial organisms, especially the ones along the Indian Ocean rim. Climbing perches(Anabantidae) are primary freshwater fishes showing a disjunct south Asian-African distribution,but with an elusive paleobiogeographic history due to the lack of fossil evidence. Here, based on an updated time-calibrated anabantiform phylogeny integrating a number of relevant fossils, the divergence between Asian and African climbing perches is estimated to have occurred in the middle Eocene(ca.40 Ma, Ma: million years ago), a time when India had already joined with Eurasia. The key fossil lineage is ?Eoanabas, the oldest anabantid known so far, from the upper Oligocene of the Tibetan *** range reconstructions suggest a Southeast Asian origin in the early Eocene(ca. 48 Ma) and subsequent dispersals to Tibet and then India for this group. Thereby we propose their westbound dispersal to Africa via the biotic bridge between India and Africa. If so, climbing perch precursors had probably followed the paleobiogeographical route of snakehead fishes, which have a slightly older divergence between African and Asian taxa. As such, our study echoes some recent molecular analyses in rejecting the previously held ‘‘Gondwana continental drift vicariance" or late Mesozoic dispersal scenarios for the climbing perches, but provides a unique biogeographical model to highlight the role of the preuplift Tibet and the docked India in shaping the disjunct distribution of some air-breathing freshwater fishes around the Indian Ocean.

关键词： Climbing perches Asian-African disjunct distribution Biogeography Indian subcontinent Tibet

Management guidelines for esophageal carcinoma 2018: Chinese standards in clinical practice

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Cancer Research 2019年第3期31卷 421-422页

作者： Yuan Feng Nan wu Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing) Department of Thoracic Surgery Ⅱ Peking University Cancer Hospital & Institute

Esophageal carcinoma is now the sixth most common cause of cancer-related deaths worldwide. China, unfortunately, locates in the highest-risk area (often referred to as the “esophageal cancer belt”) spanning from northern Iran through the Central Asian republics and into northern China. The high prevalence areas spread from south to north in China. In the highest prevalence areas, the crude incidence of esophageal cancer can even reach more than 100/100,000, nearly 7 times that of the whole country. More than 210,000 patients die from esophageal cancer in China every year, accounting for half of the esophageal cancer-related death worldwide. It is currently one of the most threatening cancers for Chinese people.

关键词： Esophageal carcinoma cancer-related deaths worldwide Chinese people

A taxonomic review of the genus Eoophyla Swinhoe, 1900(Lepidoptera: Crambidae: Acentropinae) from China

在线全文

学校读者我要写书评

暂无评论

Zoological Systematics 2019年第3期44卷 212-239页

作者： Fuqiang Chen Chunsheng wu Key Laboratory of Zoological Systematics and Evolution Institute of Zoology Chinese Academy of Sciences

Twenty-one species of the genus Eoophyla Swinhoe, 1900 are recognized from China, of which 7 species are described as new to science, namely E. tenuisa sp. nov., E. minisigna sp. nov., E. fusca sp. nov., E. clarusa sp. nov., E. leiokellula sp. nov., E. minita sp. nov. and E. ciliensis sp. nov. Two species, E. peribocalis and E. sejunctalis, are not recorded in this paper as their record were doubted. All adults and their genital structures examined are illustrated. A key to the Chinese species is provided. All type materials are deposited in IZCAS.

关键词： Pyraloidea aquatic moths taxonomy new species

Agent Based Multiviews Requirements Model

在线全文

学校读者我要写书评

暂无评论

wuhan University Journal of Natural Sciences 2006年第2期11卷 346-350页

作者： LIANG Zhengping wu Guoqingt School of Computer Wuhan University Wuhan 430072 Hubei China

Based on the current researches of viewpoints oriented requirements engineering and intelligent agent, we present the concept of viewpoint agent and its abstract model based on a recta-language for muhiviews requirements engineering. It provided a basis for consistency checking and integration of different viewpoint requirements, at the same time, these checking and integration works can automatically realized in virtue of intelligent agent＇ s autonomy, proactivenes.s and social ability. Finally, we introduce the practical application of the model by the case study of data flow diagram.

关键词： viewpoint agent agent viewpoint model

First-order perturbation approximation for rock elastic moduli in transversely isotropic media

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2017年第9期60卷 1645-1654页

作者： wu GuoChen ZHAO XiaoLong TANG Jie DU ZeYuan School of Geoscience China University of Petroleum Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and Technology

Seismic anisotropy is a relatively common seismic wave phenomenon in laminated sedimentary rocks such as shale and it can be used to investigate mechanical properties of such rocks and other geological materials. Young's modulus and Poisson's ratio are the most common mechanical properties determined in various rock engineering practices. Approximate and explicit equations are proposed for determining Young's modulus and Poisson's ratio in anisotropic rocks, in which the symmetry plane and symmetry axis of the anisotropy are derived from the constitutive equation of transversely isotropic rock. These equations are based on the media decomposition principle and seismic wave perturbation theory and their accuracy is tested on two sets of laboratory data. A strong correlation is found for Young's modulus in two principal directions and for Poisson's ratio along the symmetry plane. Further, there is an underprediction of Poisson's ratio along the symmetry axis, although the overall behavior follows the trend of the measured data. Tests on a real dataset show that it is necessary to account for anisotropy when characterizing rock mechanical properties of shale. The approximate equations can effectively estimate anisotropic Young's modulus and Poisson's ratio, both of which are critical rock mechanical data input for hydraulic fracturing engineering.

关键词： Seismic anisotropy Young's modulus Poisson's ratio Perturbation approximation

An energy constraint position-based dynamics with corrected SPH kernel

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2023年第1期66卷 144-157页

作者： Wei CAO Luan LYU Zhixin YANG Enhua wu College of Computer Science and Technology China University of Petroleum Faculty of Science and Technology University of Macau State Key Laboratory of Internet of Things for Smart City University of Macau State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences Guangzhou Greater Bay Area Virtual Reality Research Institute

We introduce an improved position-based dynamics method with corrected smoothed particle hydrodynamics(SPH) kernel to simulate deformable solids. Using a strain energy constraint that follows the continuum mechanics, the method can maintain the efficiency and stability of the position-based approach while improving the physical plausibility of the simulation. We can easily simulate the behavior of anisotropic and plastic materials because the method is based on physics. Unlike the previous position-based simulations of continuous materials, we use weakly structured particles to discretize the model for the convenience of deformable object cutting. In this case, a corrected SPH kernel function is adopted to measure the deformation gradient and calculate the strain energy on each particle. We also propose a solution for the interparticle inversion and penetration in large deformation. To perform complex interaction scenarios, we provide a simple method for collision detection. We demonstrate the flexibility, efficiency, and robustness of the proposed method by simulating various scenes, including anisotropic elastic deformation, plastic deformation, model cutting, and large-scale elastic collision.

关键词： position-based dynamics deformable solids continuum mechanics