检索结果-南通市图书馆

Analysis of ground deformation development and settlement prediction by air-boosted vacuum preloading

维普期刊数据库评论

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 Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 272-288页

作者： Shuangxi feng Huayang Lei Cheng Lin Department of Civil Engineering Tianjin UniversityTianjin300354China key Laboratory of Coast Civil Structure Safety of the Ministry of Education Tianjin UniversityTianjin300354China key Laboratory of Comprehensive Simulation of Engineering Earthquake and Urban-Rural Seismic Resilience China Earthquak AdministrationTianjin300354China Department of Civil Engineering University of VictoriaVictoriaBCV8P 5C2Canada

Vacuum preloading has been widely used to improve soft soils in coastal areas of *** increasing amount of evidence from field operations has shown that conventional vacuum preloading is prone to clogging in prefabricated vertical drains(PVDs)and demands a large volume of sand *** recent years,air-boosted vacuum preloading has been developed to overcome these limitations;however,this method still requires more data to verify its *** this study,a field test for air-boosted vacuum preloading was conducted,and a large-strain two-dimensional(2D)finite element(FE)model was developed and validated against the field test ***,a series of FE parametric analyses was performed to assess key factors,*** air injection pressure,the injection spacing,and the characteristics of cyclic injection,which affect the performance of the air-boosted vacuum *** results showed that the ground settlement and lateral displacement of the soils increased due to an increase in the injection pressure,a decrease in the injection spacing,or increases in the number and duration of the injection *** on the parametric analyses,an empirical formula for ground settlement prediction was proposed and compared with a case history reported in the literature,showing good agreement.

关键词： Air-boosted vacuum preloading Field test Numerical modeling Settlement Soft soils Ground improvement

Some Theorems for Hypersurface of Randers Spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2020年第10期36卷 1125-1139页

作者： Jin Tang LI Jian feng ZHANG School of Mathematical Sciences Xiamen UniversityXiamen 361005P.R.China Department of Mathematics Lishui UniversityLishui 323000P.R.China

In this paper,we consider the hypersurfaces of Randers space with constant flag curvature.(1)Let(M^n+1,F)be a Randers–Minkowski ***(M^n,F)is a hypersurface of(M^n+1,F)with constant flag curvature K=1,then we can prove that M is Riemannian.(2)Let(M^n+1,F)be a Randers space with constant flag ***(M,F)is a compact hypersurface of(M^n+1,F)with constant mean curvature|H|.Then a pinching theorem is established,which generalizes the result of[***.,120,1223–1229(1994)]from the Riemannian case to the Randers space.

关键词： Randers space hypersurfaces constant mean curvature constant flag curvature

MC-Nonlocal-PINNs:Handling Nonlocal Operators in PINNs Via Monte Carlo Sampling

在线全文

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2023年第3期16卷 769-791页

作者： Xiaodong feng Yue Qian Wanfang Shen Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijingChina Shandong key Laboratory of Blockchain Finance Shandong University of Finance and EconomicsJinan 250014China

We propose Monte Carlo Nonlocal physics-informed neural networks(MC-Nonlocal-PINNs),which are a generalization of MC-fPINNs in *** et al.(*** ***.400(2022),115523)for solving general nonlocal models such as integral equations and nonlocal *** to MC-fPINNs,our MC-Nonlocal-PINNs handle nonlocal operators in a Monte Carlo way,resulting in a very stable approach for high dimensional *** present a variety of test problems,including high dimensional Volterra type integral equations,hypersingular integral equations and nonlocal PDEs,to demonstrate the effectiveness of our approach.

关键词： Nonlocal models PINNs Monte Carlo sampling deep neural networks

A novel six-legged walking machine tool for in-situ operations

维普期刊数据库评论

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 Mechanical Engineering 2020年第3期15卷 351-364页

作者： Jimu LIU Yuan TIAN feng GAO State key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The manufacture and maintenance of large parts in ships,trains,aircrafts,and so on create an increasing demand for mobile machine tools to perform in-situ ***,few mobile robots can accommodate the complex environment of industrial plants while performing machining *** study proposes a novel six-legged walking machine tool consisting of a legged mobile robot and a portable parallel kinematic machine *** kinematic model of the entire system is presented,and the workspace of different components,including a leg,the body,and the head,is analyzed.A hierarchical motion planning scheme is proposed to take advantage of the large workspace of the legged mobile platform and the high precision of the parallel machine *** repeatability of the head motion,body motion,and walking distance is evaluated through experiments,which is 0.11,1.0,and 3.4 mm,***,an application scenario is shown in which the walking machine tool steps successfully over a 250 mmhigh obstacle and drills a hole in an aluminum *** experiments prove the rationality of the hierarchical motion planning scheme and demonstrate the extensive potential of the walking machine tool for in-situ operations on large parts.

关键词： legged robot parallel mechanism mobile machine tool in-situ machining

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

金融发展、现金持有水平及其市场价值

中央财经大学学报 2018年第9期 34-45页

作者：胡亚峰冯科北京大学经济学院北京大学经济学院金融系

金融发展作为宏观经济层面的一个重要因素,会对微观企业行为产生重要影响。笔者以1999—2015年中国A股非金融类上市公司的年度数据为样本,研究中国金融发展水平对中国上市公司现金持有行为的影响及其产生的经济后果。研究结果显示:(1)... 详细信息

金融发展作为宏观经济层面的一个重要因素,会对微观企业行为产生重要影响。笔者以1999—2015年中国A股非金融类上市公司的年度数据为样本,研究中国金融发展水平对中国上市公司现金持有行为的影响及其产生的经济后果。研究结果显示:(1)金融发展降低了公司现金持有量,增加了公司现金持有的边际市场价值;(2)按产权性质分组看,金融发展使得国有企业现金持有量降低的幅度要大于民营企业,现金市场价值增加的幅度要大于民营企业;(3)进一步进行稳健性和机制检验,发现结果稳健且金融发展降低了公司的现金-现金流敏感性、抑制了过度投资和减轻了代理问题。以上结果表明金融发展主要通过缓解公司外部融资约束和减轻代理问题来影响其现金持有行为。

关键词：金融发展现金持有水平现金市场价值

Digital medical technology based on 64-slice computed tomography in hepatic surgery

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2010年第9期123卷 1149-1153页

作者： FANG Chi-hua HUANG Yan-peng CHEN Mian-ling LU Chao-min LI Xiao-feng QIU wen-feng Department of Hepatobiliary Surgery Zhujiang HospitalSouthern Medical UniversityNo. 253Central Industrial RoadGuangzhouGuangdong 510282China College of Computer Sciences South China Normal UniversityGuangzhouGuangdong 510089China

Background With the rapid development of computer technology, digital medicine has become a new direction in surgery. The application of digital medicine in hepatic surgery is still at the early stage and less reported in the literature. The aim of this study was to apply digital medical technology in the context of hepatic surgery. Methods Data from 64-slice helical computed tomography of 17 patients, including 13 with hepatocellular carcinoma and 4 with hepatic hemangioma, were imported into independently developed medical image software program, segmentation and three-dimensional reconstruction were performed. The three-dimensional models were then processed with the FreeForm Modeling System. We used virtual surgical instruments to perform surgery on the models. Simulated surgeries included six hepatic segmentectomies, four left hemihepatectomies, three right hemihepatectomies for hepatocellular carcinoma, one hepatic segmentectomy, two stripping surgeries, and one irregular segmentectomy combined with stripping surgery for hemangioma. For resections involving more than three hepatic segments, total and residual functional hepatic volumes were measured before and after simulation surgery, and the resection ratio was *** The anatomy of the models was distinct and was used to localize lesions. We used virtual surgical instruments to perform simulated surgeries and used the models to optimize actual surgeries. We were able to minimize resection volume as well as surgical *** Digital medical technology is helpful in the diagnosis of hepatic disease and in optimizing surgical plans. Three-dimensional models can decrease surgical risk and help prevent postoperative hepatic failure.

关键词： digital medical technology liver failure liver simulation surgery three-dimensional reconstruction

Synthesis, Properties and Structureof a Novel Unsymmetrical Bis (phenoxo) BridgedBinuclear Copper (Ⅱ) Complex

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2001年第2期17卷 148-152页

作者： LU Tong-bu , LI Yan-wu, feng Xiao-long CAl Ji-wen, LI Xiao-yan and JI Liang-nian (Department of Chemistry and Center of Measurement, Zhongshan University, Guangzhou 510275, P. R. China) 中山大学广东广州 510275

A novel bis (phenoxo) bridged binuclear copper ( II) complex with dissimilar coordination environments was synthesized and characterized by spectroscopies and X-ray crystallography. It crystallized in the monoclinic system with space group C2/c, a=2. 241 1(2) nm, b=1. 834 2 (2) nm, c=1.877 9(2) nm, β=122.861(2)°, V=6.484 3(11) nm3, Z=8. Itconsistsof two unsymmetrical Cu (Ⅱ ) centers bridged by two phenolic oxygen atoms to yield a Cu2O2 core with the Cu-Cu separation of 0. 310 2 nm, in which Cul and Cu2 ions exhibit distorted N2O3 and N3O2 square pyramidal geometries, respectively.

关键词： Copper Binuclear complex Crystallization

在线全文

学校读者我要写书评

暂无评论

一种进气道/发动机地面匹配试验方法

航空发动机 2022年第5期48卷 161-166页

作者：冯文梁姚皆可周伟成都飞机工业(集团)有限责任公司成都610092

为了在单发试验架上模拟单发停车与双发正常工作情况下的进/发匹配安全性,提出了一种进气道/发动机地面匹配试验方法。结果表明:在单发试验台架上,通过在进气道入口前飞机对称面位置加装隔板及取消隔板实现单发停车及双发工作状态的模拟... 详细信息

为了在单发试验架上模拟单发停车与双发正常工作情况下的进/发匹配安全性,提出了一种进气道/发动机地面匹配试验方法。结果表明:在单发试验台架上,通过在进气道入口前飞机对称面位置加装隔板及取消隔板实现单发停车及双发工作状态的模拟,并根据对地面抽吸试验与缩比模型风洞试验进气道出口性能及总压恢复系数图谱的对比,证明加装隔板及取消隔板模拟双发工作与单发停车状态的合理性;根据流量标定试验结果,对抽吸试验进气道出口参数进行修正,获取全尺寸进气道更加精确的性能,并与缩比模型风洞试验结果对比,全尺寸进气道性能优于缩比模型风洞试验结果;通过发动机地面开车,有效模拟了双发工作与单发停车条件下发动机不同转速及加减速过程中的进发匹配特性,确保了飞机滑行及试飞安全。

关键词：进气道/发动机匹配流量标定抽吸试验缩比模型风洞试验全尺寸进气道综合畸变指数

Fault Tolerant Approach for Data Encryption and Digital Signature Based on ECC System

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2005年第1期10卷 13-16页

作者： ZENGYong MAJian-feng Thekeyl.aboratoryofComputerNetworkandInformationSecurityofMinistryofEducation XidianUniversityXi＇an710071ShaanxiChina Thekeyl.aboratoryofComputerNetworkandInformationSecurityofMinistryofEducation XidianUniversityXi＇an710071ShaanxiChina

An integrated fault tolerant approach for data encryption and digitalsignature based on elliptic curve cryptography is proposed. Phis approach allows the receiver toverify the sender's identity and can simultaneously deal with error detection and data *** to three errors in our approach can be detected and corrected. This approach has at least thesame security as that based on RSA system, but smaller keys to achieve the same level of *** approach is more efficient than the known ones and more suited for limited environments likepersonal digital assistants (PDAs), mobile phones and smart cards without RSA co-processors.

关键词： fault tolerance dliptic curve cryptography error correction