检索结果-南通市图书馆

Relationship Between Coarse/Fine Aggregate Space Coefficient and Properties of Self-compacting Concrete

在线全文

学校读者我要写书评

暂无评论

武汉理工大学学报 2010年第17期32卷 158-164,169页

作者： LONG G C LIU y H xie y J School of Civil Engineering and Architecture Central South UniversityChangsha 410075China Quality Intendance and Inspect Station of Construction Engineering Chenzhou 423000China

For the sake of expounding the relationship between coarse/fine aggregate volume content and properties of self-compacting concrete(SCC),a parameter of aggregate space coefficient is proposed to study systematically the effects of fine/ coarse aggregates on workability,strength and volume stability of SCC by experiments. The optimized coarse/fine aggregates volume content of SCC was discussed with regard to specified properties. Results indicate there is a close relationship between aggregate space coefficient and properties of SCC not only in fresh state but also in hardened state. With the increasing coarse/fine aggregate space coefficients,workability of fresh SCC will be improved,the compressive strength decreases slightly and shrinkage of SCC however increases. When coarse aggregate space coefficient ranges from 1.2 to 1.7 and the fine aggregate space coefficients is from 0.6 to 1.0,SCC can meet self-compactability requirements in fresh state and have a good volume stability and appropriate strength in hardened state. The results will benefits for developing a new mixing design method for SCC.

关键词： self-compacting concrete aggregate space coefficient workability compressive strength shrinkage

Preparation of Anhydrate Phosphogypsum Binders

在线全文

学校读者我要写书评

暂无评论

武汉理工大学学报 2010年第17期32卷 193-195,200页

作者： yANG M xie y CHENG J K PANG y School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550003China

In this work,phosphogypsum(PG) with a small amount of lime was thermally pretreated at 450 ℃ to produce anhydrate gypsum for the purpose of searching new ways for utilization of waste PG. Additives,K2SO4 and one selected seed crystal(SC),were used as activator for anhydrate PG. The hydration characteristics of the anhydrate PG binders were investigated by determination of the setting time,the ratio of hydrated anhydrate PG,the compressive strength development,and the microstructure of the hardenite. The resistance to water was studied by measuring mass loss of binders exposed to hydrodynamic water. Results suggest that activated by K2SO4 and SC,anhydrate PG hydrates much more rapidly than that without additives. The anhydrate PG binder with K2SO4 and SC has proper setting time and good strength developments. SEM photos show that the set binders have hydrated products of rodlike and regularly shaped crystals. Those crystals connected closely,and the hardenite has a compact structure,which is beneficial to the obtainment of good properties.

关键词： anhydrate PG binders activator hydration

In situ TEM observations and molecular dynamics simulations of deformation defect activities in Mg via nanoindentation

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第12期11卷 4513-4524页

作者： yi-Cheng Lai yubin ying Digvijay yadav Jose Guerrero yong-Jie Hu Kelvin y.xie Department of Materials Science and Engineering Texas A&M UniversityCollege StationTX 77845USA Department of Materials Science and Engineering Drexel UniversityPhiladelphiaPA 19104USA

In this work, we performed in situ nanoindentation in TEM to capture the real-time dislocation and twinning activities in pure Mg during loading and unloading. We demonstrated that the screw component of dislocations glides continuously, while the edge components rapidly become sessile during loading. The twin tip propagation is intermittent, whereas the twin boundary migration is more continuous. During unloading, we observed the elastic strain relaxation causes both dislocation retraction and detwinning. Moreover,we note that the plastic zone comprised of dislocations in Mg is well-defined, which contrasts with the diffused plastic zones observed in face-centered cubic metals under the nanoindentation impressions. Additionally, molecular dynamics simulations were performed to study the formation and evolution of deformation-induced crystallographic defects at the early stages of indentation. We observed that,in addition to dislocations, the I1stacking fault bounded with a Frank loop can be generated from the plastic zone ahead of the indenter, and potentially serve as a nucleation source for abundant dislocations observed experimentally. These new findings are anticipated to provide new knowledge on the deformation mechanisms of Mg, which are difficult to obtain through conventional ex situ approaches. These observations may serve as a baseline for simulation work that investigate the dynamics of dislocation slip and twinning in Mg and alloys.

关键词： In situ TEM Molecular dynamics simulation Dislocation Twinning Mg Nanoindentation

Characteristics and accumulation mechanisms of the Dongfang 13-1 high temperature and overpressured gas field in the yinggehai Basin, the South China Sea

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2014年第8期57卷 2799-2807页

作者： xie yuHong HUANG BaoJia Zhanjiang Branch China National Offshore Oil Corporation China Limited

The Dongfang 13-1 is located in the diapiric structure belt of the yinggehai Basin. The formation pressure of its main gas res- ervoir in the Miocene Huangliu Formation is up to 54.6 MPa （pressure coefficient=l.91） and the temperature is as high as 143°C （geothermal gradient 4.36°C/100 m）, indicating that it is a typical high-temperature and overpressured gas reservoir. The natural gas is interpreted to be coal-type gas derived from the Miocene mature source rocks containing type Ⅱ2-Ⅲ kero- gens as evidenced by high dryness index of up to 0.98 and heavy carbon isotopes, i.e., the δ13C2 ranging from -30.76%o to -37.52%o and δ13C2 ranging from -25.02%o to -25.62%o. The high temperature and overpressured Miocene petroleum system is related mainly to diapir in the yinggehai Basin and contains more pore water in the overpressured reservoirs due to under- compaction process. The experimental and calculated results show that the solubility of natural gas in formation water is as high as 10.5 m3/m3 under the temperature and pressure conditions of the Sanya Formation, indicating that at least part of the gas may migrate in the form of water-soluble phase. Meanwhile, the abundant gas source in the Basin makes it possible for the rapid saturation of natural gas in formation water and exsolution of soluble gas. Therefore, the main elements controlling formation of the Dongfang 13-1 gas pool include that （1） the diapir activities and accompanying changes in temperature and pressure accelerate the water-soluble gas exsolution and release a lot of free gas; （2） submarine fan fine sandstone in the Huangliu Formation provides good gas-water segregation and accumulation space; and （3） the overlying overpressured mud rocks act as effective caps. The accumulation mechanism reveals that the high temperatural and high pressure structure belt near the diapir structures has a good potential for large and medium-sized gas field exploration.

关键词： Dongfang 13-1 high temperature and overpressured gas field accumulation mechanism diapiric belt yinggehai Basin

同方期刊数据库

Guideline on Chinese Medicine Rehabilitation for Idiopathic Pulmonary Fibrosis

在线全文

学校读者我要写书评

暂无评论

World Journal of Traditional Chinese Medicine 2023年第4期9卷 475-484页

作者： Jian-Sheng Li Ming-Hang Wang yang xie 机构不祥

Foreword Note:Some of the elements of this document may be the subject of patent *** shall not be held responsible for identifying any or all such patent *** drafting organizations:Henan University of Chinese Medicine... 详细信息

关键词： Henan patent Medicine

Variational Corner Transfer Matrix Renormalization Group Method for Classical Statistical Models

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2022年第6期39卷 65-70页

作者： X.F.Liu y.F.Fu W.Q.yu J.F.yu Z.y.xie Department of Physics Renmin University of ChinaBeijing 100872China School of Physics and Electronics Hunan UniversityChangsha 410082China

In the context of tensor network states,we for the first time reformulate the corner transfer matrix renormalization group(CTMRG)method into a variational bilevel optimization *** solution of the optimization problem corresponds to the fixed-point environment pursued in the conventional CTMRG method,from which the partition function of a classical statistical model,represented by an infinite tensor network,can be efficiently *** validity of this variational idea is demonstrated by the high-precision calculation of the residual entropy of the dimer model,and is further verified by investigating several typical phase transitions in classical spin models,where the obtained critical points and critical exponents all agree with the best known results in *** extension to three-dimensional tensor networks or quantum lattice models is straightforward,as also discussed briefly.

关键词： tensor variational straight

A STUDy OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 27-34页

作者： X.B. Li y.Q. xie y.Z. Nie H.J. Peng H.J. Tao F.X. yu College of Materials Science and Engineering Central South University Changsha 410083 China

On the basis of energy and shape method for the determination of the valence bond （ VB ） structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is ec^29907. （sc^0.4980 ＋ dc^2.4927） ef^1.0098 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.

关键词： valence bond structure temperature titanium

The mechanical behavior of nanoscale metallic multilayers:A survey

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第3期31卷 319-337页

作者： Q.Zhou J.y.xie F.Wang P.Huang K.W.Xu T.J.Lu State-Key Laboratory for Mechanical Behavior of Material Xi’an Jiaotong University State-Key Laboratory for Mechanical Structure Strength and Vibration Xi’an Jiaotong University

The mechanical behavior of nanoscale metallic multilayers （NMMs） has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of micro- laminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size- dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plas- tic deformation physics of NMMs. We hope this review could accomplish two purposes：（1） introducing the basic concepts of scaling and dimensional analysis to scientists and engi- neers working on NMM systems, and （2） providing a better understanding of interface behavior and the exceptional qual- ities the interfaces in NMMs display at atomic scale.

关键词： Multilayer Interface Microstructure Mechanical behavior

阳离子-π相互作用调控提升单原子催化剂性能的通用策略

在线全文

学校读者我要写书评

暂无评论

中国科学：化学 2024年第7期54卷 969-970页

作者：谢毅中国科学技术大学合肥微尺度物质科学国家研究中心合肥230026

金属单原子催化剂具有金属原子利用率高、金属活性位点可设计性强、金属配位不饱和度高等优势,在众多催化反应过程中展现出优异的性能,是当前能源转换材料领域的研究前沿和热点[1].由于金属单原子具有较高的表面能,其容易发生聚集,需要... 详细信息

金属单原子催化剂具有金属原子利用率高、金属活性位点可设计性强、金属配位不饱和度高等优势,在众多催化反应过程中展现出优异的性能,是当前能源转换材料领域的研究前沿和热点[1].由于金属单原子具有较高的表面能,其容易发生聚集,需要将金属单原子锚定在合适的载体材料上并形成强相互作用,以抑制金属单原子的迁移团聚,从而实现金属组分的原子级分散[2].

关键词：催化反应过程单原子原子利用率强相互作用不饱和度载体材料能源转换原子级