检索结果-南通市图书馆

Experimental study on the influence of hydrostatic stress on the Lode angle effect of porous rock

International Journal of Mining Science and Technology 2022年第4期32卷 727-735页

作者： Zhenlong Song Zhenguo Zhang p.G.Ranjith Wanchun Zhao Chao Liu Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhenGuangdong 518055China State Key Laboratory of Coalmine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China Deep Earth Energy Research Laboratory Department of Civil EngineeringMonash UniversityMelbourneVictoria 3800Australia School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of Electrical Engineering&Information Northeast Petroleum UniversityDaqing 163318China

To investigate the deformation mechanisms of rock under hydrostatic stress, destructive experiments were conducted on sandstone under different levels of hydrostatic stress and stress Lode angles. The results reveal that the shape of the strength envelope on the π plane gradually changes from the shape of the Lade criterion to the shape of the Drucker-prage criterion with an increase in hydrostatic ***, there exists a deviation between the strain and stress paths for porous rocks on the π plane,and the deviation decreases with an increase in stress Lode angle and hydrostatic stress. A rock failure hypothesis based on the rock porous structure was proposed to investigate the reasons for the abovementioned phenomena. It was found that the shear expansion in the minimum principal stress direction is the dominant factor affecting the Lode angle effect(LAE);the magnitude of the hydrostatic stress induces the variation of the porous structure and influences the shear expansion. Therefore, the hydrostatic stress state affects the LAE. The failure hypothesis proposed in this paper can clarify the hydrostatic stress effect, LAE, and the variation of the rock strength envelope shape.

关键词： Lode angle effect hydrostatic stress effect Strength envelope curve porous structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

ON A COUpLED INTEGRO-DIFFERENTIAL SYSTEM INVOLVING MIXED FRACTIONAL DERIVATIVES AND INTEGRALS OF DIFFERENT ORDERS

引用

Acta Mathematica Scientia 2021年第4期41卷 1366-1384页

作者： Bashir AhMAD Ravi p.AGARWAL Abrar BROOM Ahmed ALSAEDI Nonlinear Analysis and Applied Mathematics(NAAM)-Research Group Department of MathematicsFaculty of ScienceKing Abdulaziz UniversityP.O.Box 80203Jeddah 21589Saudi Arabia Department of Mathematics Texas A&M UniversityKingsvilleTexas 78363-8202USA

By applying the standard fixed point theorems,we prove the existence and uniqueness results for a system of coupled differential equations involving both left Caputo and right Riemann-Liouville fractional derivatives and mixed fractional integrals,supplemented with nonlocal coupled fractional integral boundary *** example is also constructed for the illustration of the obtained results.

关键词： Fractional differential equations Caputo and Riemann-Liouville fractional derivatives systems existence fixed point theorems

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimal Control of Semilinear Elliptic Variational Bilateral problem

引用

Acta Mathematica Sinica,English Series 2000年第1期16卷 123-140页

作者： Qihong Chen Institute of Mathematics,Fudan University,Shanghai 200433,p.R.China Shanghai Normal University,Shanghai 200023,p.R.China Institute of Mathematics Fudan University Shanghai 200433 P.R. China Shanghai Normal University Shanghai 200023 P.R. China

This paper is concerned with an optimal control problem for semilinear elliptic variational inequalities associated with bilateral *** and optimality conditions of the optimal pair are established.

关键词： Elliptic bilateral variational inequality Optimal control Existence Optimality condition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Upper bound analysis for hybrid sheet metals extrusion process through curved dies

引用

Transactions of Nonferrous Metals Society of China 2014年第10期24卷 3285-3292页

作者： h.hAGhIGhAT h.ShAYESTEh Mechanical Engineering Department Razi University

The extrusion process of hybrid sheet metals through arbitrarily curved dies was analyzed by the method of upper bound. The material under deformation was divided into two deformation regions, bimetal and mono-metal regions, and the flow of the material in each region was assumed as plane strain state. The internal, shearing and frictional power terms were derived and they were used in the upper bound model. The extrusion forces for two types of die shapes, an optimum wedge shaped die and an optimum streamlined die shape for a hybrid sheet composed of copper as sleeve and aluminum as core were determined. The corresponding results for those two die shapes were also determined by using the finite element code, ABAQUS, and compared with the upper bound results. These comparisons show a good agreement.

关键词： extrusion hybrid sheet metal upper bound method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Recollections of my mentor,Donald ***

引用

Earthquake Science 2022年第1期35卷 14-16页

作者： Stephen p.Grand Department of Geological Sciences Jackson School of GeosciencesUniversity of Texas at AustinTX78712USA

I arrived at Caltech as a graduate student in the summer of *** a BSc degree in physics,I knew little to nothing about seismology or *** Seismo Lab encouraged new students to immediately start some research with a great latitude on what to work *** summer I started projects relocating aftershocks of the 1978 Oaxaca earthquake with Karen McNally,learning a normal mode code with Bernard Minster,and investigating the source mechanism of the 1979 *** earthquake with hiroo Kanamori.

关键词： earthquake latitude geophysics

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Are hyoliths palaeozoic lophophorates?

引用

National Science Review 2020年第2期7卷 453-469页

作者： Fan Liu Christian B Skovsted Timothy p Topper Zhifei Zhang Degan Shu State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life and Environments Department of Geology Northwest University Department of palaeobiology Swedish Museum of Natural History

The phylogenetic position of hyoliths has long been unsettled, with recent discoveries of a tentaculate feeding apparatus(‘lophophore’) and fleshy apical extensions from the shell(‘pedicle’) suggesting a lophophorate affinity. here, we describe the first soft parts associated with the feeding apparatus of an orthothecid hyolith, Triplicatella opimus from the Chengjiang biota of South China. The tuft-like arrangement of the tentacles of T. opimus differs from that of hyolithids, suggesting they collected food directly from the substrate. A reassessment of the feeding organ in hyolithids indicates that it does not represent a lophophore and our analysis of the apical structures associated with some orthothecids show that these represent crushed portions of the shell and are not comparable to the brachiopod pedicle. The new information suggests that hyoliths are more likely to be basal members of the lophotrochozoans rather than lophophorates closely linked with the phylum Brachiopoda.

关键词： orthothecid the Chengjiang Lagerst¨atte Cambrian soft parts lophophore

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Artificial ground freezing of underground mines in cold regions using thermosyphons with air insulation

引用

International Journal of Mining Science and Technology 2024年第5期34卷 643-654页

作者： Ahmad F.Zueter Mohammad Zolfagharroshan Navid Bahrani Agus p.Sasmito Department of Civil and Resource Engineering Dalhousie UniversityHalifax B3H4R2Canada Department of Mining Engineering McGill UniversityMontreal H3A0E8Canada

Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental *** this study,a novel AGF technique is proposed deploying available cold wind in cold *** is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling *** introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration *** design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the *** Canadian mines are considered:the Cigar Lake Mine and the Giant *** results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake ***,a cooling load of 2.4 GWh can be saved at the Cigar Lake ***,this study provides mining practitioners with sustainable solutions of underground AGF.

关键词： Artificial ground freezing Underground mining Sustainable mining Thermosyphon Air insulation Cold regions

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Fabrication of 4h-SiC Merged pN-Schottky Diodes

引用

Journal of Semiconductors 2001年第3期22卷 265-270页

作者：张玉明张义门 p.Alexandrov J.h.Zhao 西安电子科技大学微电子所 DepartmentofElectricalandComputerEngineering TheStateUniversityofNewJerseyNJ08854-8058USA

The design, fabrication and characteristics of 4h SiC merged pN Schottky (MpS) diodes with Ni Schottky contact and junction termination extension (JTE) edge termination are reported. A multiple energy implantation Al in the surface of the n - drift region below the face to face Schottky metal formed pn junctions, which screen the Schottky contact from high electrical, post implantation annealing has been done at 1500℃ for 30min in the ultra high purity Ar ambient. The devices can block more than 600V reverse voltage and the lowest leakage current at -600V is 1×10 -3 A/cm 2, while the forward current density at 3V is more than 200A/cm 2 for 1000μm devices, 1000A/cm 2 at 3 5V for 300μm devices.

关键词： power devices SiC semiconductor diode MpS

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

AN ANALYSIS OF ThE OXYGEN BALANCE IN AN ANOXIC TIDAL RIVER

引用

Journal of hydrodynamics 1994年第4期6卷 83-92页

作者： Joseph h. W. Lee, K. W. Choi (Department of Civil and Structural Engineering, University of hong Kong)Chen hui-guo Lin Ming-he(Environmental Sciences Research Centre, Zhongshan University, Guangzhou 510275, p. R. China) Department of Civil and Structural Engineering University of Hong Kong Hong Kong Environmental Sciences Research Centre Zhong.shan University Guangzhou 510275 China

A time-dependent, mixed-segment, slack tide oxygen balance model has been developed for the study of a heavily polluted tidal river discharging to a coastal *** and reaeration, BOD settling, benthal demand, freshwater flushing, and tidal mixing are the key processes modelled. Significant features of the model include the oxygen balance formulation under anoxic conditions and the tidal exchange condition at the seaward boundary. The simple model enables a clear and consistent interpretation of a set of dry season water quality data and an assessment of the assimilative capacity of the river is also made.

关键词： tidal river coastal bay water quality oxygen balance.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

patented Biologically-inspired Technological Innovations: A Twenty Year View

引用

Journal of Bionic Engineering 2006年第1期3卷 39-41页

作者： Richard h. C. Bonser Centre for Biomimetics University of Reading Reading RG6 4EF UK

publication rate of patents can be a useful measure of innovation and productivity in fields of science and technology. To assess the growth in industrially-important research, I conducted an appraisal of patents published between 1985 and 2005 on online databases using keywords chosen to select technologies arising as a result of biological inspiration. Whilst the total number of patents increased over the period examined, those with biomimetic content had increased faster as a proportion of total patent publications. Logistic regression analysis reveals that we may be a little over half way through an initial innovation cycle inspired by biological systems.

关键词： patent biomimetic bionic technology commercialization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：