检索结果-南通市图书馆

Influence of deviatoric stress on rockburst occurrence:An experimental study

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2018年第5期28卷 763-766页

作者： Thomas Bruning Murat Karakus Selahattin Akdag Giang d.nguyen david Goodchild School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaide 5005Australia OZ Minerals 2 Hamra DriveAdelaide AirportSA5950Australia

As mining delves deeper into the crust, it is necessary to investigate the complex rock responses associated with higher stress gradients. Therefore, it is essential to better understand the mechanisms associated with the rockburst phenomenon. However, due to the large-scale and difficult monitoring of real mining excavations, laboratory scale tests must be utilised to determine the conditions conducive to burst. To this end, this research focuses on the implementation of a new rockburst testing apparatus to replicate the stress conditions of a rock mass excavation at the time of bursting. This apparatus allows the determination of rockburst stresses and a relationship between deviatoric stress and in-situ pressure/depth. Using this relationship it is then possible to estimate the standardised stress levels for a certain rock type which might lead to rockburst occurrence. Furthermore, it is demonstrated that with increasing in-situ pressure, the likelihood(measured as a lower differential stress) and the extent(indicated by the increasing range of deviatoric stress) of rockburst increases. These findings provide valuable information about the conditions necessary for bursting in deep mining.

关键词： Rockburst test Hollow cylinder Hard rock In-situ stress

Approximate graphical method of solving Fermi level and majority carrier density of semiconductors with multiple donors and multiple acceptors

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2011年第6期32卷 1-6页

作者： ken K.Chin department of Physics and Apollo CdTe Solar Energy Research Center New Jersey Institute of Technology

We present a generic approximate graphical method for determining the equilibrium Fermi level and majority carrier density of a semiconductor with multiple donors and multiple acceptors compensating each other. Simple and easy-to-follow procedures of the graphical method are *** graphically plotting two wrapping step functions facing each other,one for the positive hole-ionized donor and one for the negative electron-ionized acceptor,we have the crossing point that renders the Fermi level and majority carrier *** the graphical method,new equations are derived,such as the carrier compensation proportional to N;/N;,not the widely quoted N;-N;.Visual insight is offered to view not only the result of graphic determination of Fermi level and majority carrier density but also the dominant and critical pair of donors and acceptors in *** graphical method presented in this work will help to guide the design,adjustment,and improvement of the multiply doped *** of this approximate graphical method with previous work on compensation,and with some experimental results,is *** work in the field is proposed.

关键词： doping compensation Fermi level carrier density graphical method ionization

A new formula for screening metabolic syndrome in Asians:skin fold thickness at A8 point on Erdheim diagram and waist circumference

在线全文

学校读者我要写书评

暂无评论

Journal of Geriatric Cardiology 2007年第1期4卷 32-41页

作者： Toan C nguyen Thai Q Ngo Khoa TA Pham Son V nguyen Hieu T Luong Cong d nguyen Vietnam Military Medical University Ha Dong Town Ha Tay Province Vietnam department of Cardiology Hospital 103 Vietnam

Background and objectives Recent studies have shown that abdominal obesity is an important component for the diagnosis of metabolic syndrome (MS) and MS is a high risk factor for cardiovascular disease and diabetes mellitus. The aim of this study was to develop a new formula for screening and diagnosis of MS using the waist circumference (WC) and skin fold thickness at the point A8 (SFA8) on the Erdheim diagram. Methods A total of 358 essential hypertensive patients (189 male and 169 female) with a mean age of 59.0±9.7 years were included; 151 healthy people (79 male, 72 female) with a mean age of 57.3±12.1 years (similar to hypertensive patients) who were non-hypertensive and non-diabetic served as a control group. All subjects had no evidence of hepatic, renal, or endocrine disease as determined by history, physical examination and screening blood tests. Height, weight, WC, SFA8, blood pressure (BP), fasting plasma glucose, HdL-cholesterol and triglyceride levels were measured in all subjects. Abdominal obesity measured by WC using the Asia-Pacific criteria (IdFA) was applied for meeting the MS definition. The normal value of SFA8 was measured in the non- MS group. Relationships between SFA8 and systolic BP, diastolic BP, fasting plasma glucose, HdL-cholesterol and triglyceride levels were calculated in the control group. A new formula was developed according to high SFA8 and high WC. Results The normal value of SFA8 in non-MS group was 23.6±7.2 mm in male and 26.5±4.6 mm in female, respectively. The value of SFA8 in MS group was 36.7± 7.4 mm in male and 38.9 ± 8.1 mm in female, respectively. The value of WC in MS group and non-MS group were 92.5±3.0 cm and 79.4±6. 1 cm in male and 86.3±6.4 cm and 74.7±5.4 cm in female, respectively. There was a correlation between SFA8 and systolic BP, diastolic BP, fasting plasma glucose, HdL-cholesterol and triglyceride in control group (the correlation coefficients were 0.29, 0.23, 0.25, -0.31 and 0.46, respectively, P < 0.01)

关键词： waist circumference skin fold thickness metabolic syndrome

Multiscale analysis of composite material reinforced by randomly-dispersed particles

在线全文

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2012年第1期3卷 2-13页

作者： Jiaoyan Li James d.Lee ken P.Chong The George Washington University WashingtonDC 20052USA National Institute of Standards and Technology GaithersburgMD 20899USA

A multiscale analysis method is presented in which detailed information on the microscopic level is incorporated into macroscopic models capable of simulating damage evolution and ultimate *** composite considered is reinforced by randomly-dispersed particles,which reflects the statistical characteristics of real materials,such as cement-based ***,a three-dimensional material body is decomposed into many unit *** unit cell is reinforced by a cylindrical particle,the orientation of which is characterized by three Euler angles generated by the random number *** on a detailed finite element analysis,the material properties of the representative volume element are *** verification,the properties of the cylindrical particles are set equal to those of the matrix and the computed‘composite’properties reduce exactly to those of the‘isotropic’material,as *** coordinate transformation,the effective material properties of each unit cell are *** assembly of stiffness matrices of all unit cells leads to the stiffness matrix of the whole *** the simple tension loading condition,the initial damaged unit cell can be identified according to the vonMises yield *** stiffness of the damaged unit cell will then be reduced to zero and it will cause stress redistribution and trigger further *** was found that the reinforcement is effective to mitigate and arrest the damage propagation,and therefore prolongs the material’s *** results suggest that the hierarchical coupling approaches used here may be useful for material design and failure protection in composites.

关键词： multiscale analysis random response finite element method representative volume element Euler angle damage propagation

Skin fold thickness at abdomen:a simple anthropometric measurement may compliment metabolic syndrome definition in patients with normal waist circumference

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 Geriatric Cardiology 2006年第2期3卷 85-92页

作者： Toan C nguyen Thai Q Ngo Son V nguyen Hieu T Luong Khoa TA Pham Cong d nguyen Vietnam Military Medical University Ha ToyVietnam

Backgroud and Objectives Previous studies have reported that skin fold thickness (SF) strongly correlated with insulin resistance in the metabolic syndrome (MetS). In this study, we developed a MetS definition by SF at A8 point (SFA8) on Erdheim diagram(MetSSFA8) in essential hypertensive patients. Subjects and Methods Medical records of 268 essential hypertensive patients (126males and 122 females) were analyzed, including 210 non-diabetic patients (NdM group) and 58 patients with diabetes (dM group).The mean age was 61.4 ± 9.9 and 59.0 ± 11.0 years, respectively. The control group consisted of 90 non-diabetic, non-hypertensive patients with a mean age of 58.0 ± 11.3 years. The proposed MetSSFA8 definition included SFA8 specific values ( ≥30 mm in female and ≥27 mm in male) and at least two of the following: raised triglyceride levels ( ≥1.7 mmol/L), or specific treatment for this lipid abnormality; raised blood pressure (SBP≥130 mmHg and/or dBP≥85 mmHg), or treatment of previously diagnosed hypertension;reduced HdL-cholesterol (＜ 1.03 mmol/L in men, ＜1.29 mmol/L in women), or specific treatment for this lipid abnormality; raised fasting plasma glucose (≥5.6 mmol/l), or previously diagnosed dM. Metabolic Syndrome by the National Cholesterol Education Program and International diabetes Federation definitions were determined with abdominal obesity defined by Asia-Pacific criteria for waist circumference (NCEPA and IdFA). Results The percentage of MetS as defined by NCEPA, IdFA and MetSSFA8 in NdM group was lower than that of NCEPA, IdFA and MetSSFA8 in dM group [OR=7.7 (95%CI, 2.9-20.2) and 2.5 (95%CI, 1.4-4.8) and 2.7(95%CI, 1.3-5.6), respectively] and higher than that of the control group [OR=53.3 (95%CI, 16.7-170.6), 5.8 (95%CI, 2.6-13.2) and18.8 (95%CI, 7.3-48.7), respectively]. The percentage of MetS by NCEPA, IdFA and MetSSFA8 in males in NdM group was lower than the percentage of MetS by NCEPA, IdFA and MetSSFA8 in females in NdM group (50.8% and 77.9%, P＜ 0.0

关键词： skin fold thickness metabolic syndrome hypertension

Mathematical modeling and numerical computation of the effective interfacial conditions for Stokes flow on an arbitrarily rough solid surface

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2021年第5期42卷 721-746页

作者： A.T.TRAN H.LE QUANG Q.C.HE d.H.nguyen Research and Application Center for Technology in Civil Engineering University of Transport and CommunicationsHanoi 10000Vietnam Laboratoire Modelisation et Simulation Multi-Echelle Unite Mixte de Recherche 8208Centre National de la Recherche ScientifiqueUniversite Gustave EiffelMarne-la-Vallee F-77454France School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

The present work is concerned with a two-dimensional(2d)Stokes flow through a channel bounded by two parallel solid *** distance between the walls may be arbitrary,and the surface of one of the walls can be arbitrarily *** main objective of this work consists in homogenizing the heterogeneous interface between the rough wall and fluid so as to obtain an equivalent smooth slippery fluid/solid interface characterized by an effective slip *** solve the corresponding problem,two efficient numerical approaches are elaborated on the basis of the method of fundamental solution(MFS)and the boundary element methods(BEMs).They are applied to different cases where the fluid/solid interface is periodically or randomly *** results obtained by the proposed two methods are compared with those given by the finite element method and some relevant ones reported in the *** comparison shows that the two proposed methods are particularly efficient and accurate.

关键词： effective slip length method of fundamental solution(MFS) boundary element method(BEM) Stokeslet micro-channel fluid/solid interface

Hardy factorization in terms of fractional commutators in Lorentz spaces

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2022年第5期17卷 853-873页

作者： nguyen Anh dAO Institute of Applied Mathematics University of Economics Ho Chi Minh CityHo Chi Minh CityVietnam

We provide a constructive proof of H^(1)(R^(d))(the classical Hardy space)factorization in terms of fractional commutators in Lorentz *** a direct application,we obtain a characterization of functions in BMO ***,we al... 详细信息

关键词： BMO CMO Lorentz space commutator Hardy space Riesz potentia

differential regulation of protein synthesis in skeletal muscle and liver of neonatal pigs by leucine through an mTORC1-dependent pathway

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 Animal Science and Biotechnology 2012年第1期3卷 32-41页

作者： Agus Suryawan Hanh V nguyen Rosemarie d Almonaci Teresa A davis department of Pediatrics Baylor College of Medicine United States Department of Agriculture/Agriculture Research Service Children's Nutrition Research Center 1100 Bates Street Houston TX 77030 USA

Neonatal growth is characterized by a high protein synthesis rate that is largely due to an enhanced sensitivity to the postprandial rise in insulin and amino acids, especially leucine. The mechanism of leucine＇s action in vivo is not well understood. In this study, we investigated the effect of leucine infusion on protein synthesis in skeletal muscle and liver of neonatal pigs. To evaluate the mode of action of leucine, we used rapamycin, an inhibitor of mammalian target of rapamycin （mTOR） complex-1 （mTORC1）. Overnight-fasted 7-day-old piglets were treated with rapamycin for 1 hour and then infused with leucine （400 μmol·kg^-1·h^-1） for 1 hour. Leucine infusion increased the rate of protein synthesis, and ribosomal protein S6 kinase 1 （S6K1） and eukaryotic initiation factor （elF） 4E-binding protein-1 （4E-BP1） phosphorylation in gastrocnemius and masseter muscles （P 〈 0.05）, but not in the liver. The leucine-induced stimulation of protein synthesis and S6K1 and 4E-BP1 phosphorylation were completely blocked by rapamycin, suggesting that leucine action is by an mTORC1-dependent mechanism. Neither leucine nor rapamycin had any effect on the activation of the upstream mTQRC1 regulators, AMP-activated protein kinase and protein kinase B, in skeletal muscle or liver. The activation of elF2α and elongation factor 2 was not affected by leucine or rapamycin, indicating that these two pathways are not limiting steps of leucine-induced protein synthesis. These results suggest that leucine stimulates muscle protein synthesis in neonatal pigs by inducing the activation of mTORC1 and its downstream pathway leading to mRNA translation.

关键词： leucine mTORC1 neonatal pigs rapamycin skeletal muscle

Evaluation of the propensity of strain burst in brittle granite based on post-peak energy analysis

在线全文

学校读者我要写书评

暂无评论

Underground Space 2021年第1期6卷 1-11页

作者： Selahattin Akdag Murat Karakus Giang d.nguyen Abbas Taheri Thomas Bruning School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaideSAAustralia

The increasing demand for resources and depletion of near ground mineral resources caused deeper mining operations under highstress rock mass *** a result of this,strain burst,which is the sudden release of stored strain energy in the surrounding rock mass,has become more prevalent and created a considerable threat to workers and construction *** is,therefore,imperative to understand how strain burst mechanism and stored excess strain energy are affected due to the high confinement in deep underground *** this purpose,post-peak energy distributions for brittle rocks were investigated using a newly developed energy calculation method associated with acoustic emission(AE).A series of quasi-static uniaxial and triaxial compression tests controlled by the circumferential expansion were ***-back behaviour known as Class-II behaviour associated with energy evolution and the material response under self-sustaining failure were analysed on granites under a wide range of confining pressures(0–60 MPa).The experimental results underline that the energy evolution characteristics are strongly linked to *** elastic strain energy(dUE),energy consumed by dominating cohesion weakening(dUCW)and energy dissipated during mobilisation of frictional failure(dUFM)showed a rising trend as the confining pressure was *** intrinsic ejection velocity was proposed to express the propensity of strain burst that was purely determined by the excess strain energy released from Class II rock.

关键词： Strain burst Energy balance Class II failure mode Self-sustaining failure Triaxial compression test Circumferential strain control