检索结果-南通市图书馆

CRACK GROWTH BEHAVIOR AND fRACTURE fEATURE Of GH2132 UNDER CREEP-fATIGUE CONDITIONS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1997年第6期10卷 495-500页

作者： Geng, M.f. Luoyang Ship Material Research Inst Luoyang China

The superalloy GH2132 is equivalent to A286. The tests were carried out at 550°C under various cyclic frequencies (hold time) and load levels, and the fracture surfaces were examined by using a scanning electron microscope. It was shown that the fracture mode of creep-fatigue and the effect of cyclic loading on crack growth change with the growth of crack and the increase of net-section stress, and both are reversed when the net-section stress is up to the yield stress of material. When σn0.2, cracking is predominantly cyclic-dependent transgranular and cyclic loading accelerates creep crack growth, whereas when σn>σ0.2, the case is reversed.

关键词： Chromium alloys Crack propagation Creep fracture Nickel alloys Rotating disks Superalloys

Secondary neurogenesis and telencephalic organization in zebrafish and mice: a brief review

在线全文

学校读者我要写书评

暂无评论

Integrative Zoology 2009年第1期4卷 123-133页

作者： Mario f.WULLIMANN Department of Biology II Ludwig-Maximilians-UniversityMunich-MartinsriedGermany

Most zebrafish neurodevelopmental studies have focused on the embryo,which is characterized by primary neurogenesis of mostly transient *** neurogenesis becomes dominant in the hatching larva,when major brain parts are established and begin to *** developmental period allows for a comparative analysis of zebrafish brain organization with amniotes at equivalent stages of *** a particular time window,the early forebrains of mice(Embyronic stage[E]12.5/13.5 days[d])and zebrafish(3 d)reveal highly comparable expression patterns of genes involved in neurogenesis,for example proneural and other transcription factors(Neurogenin1,NeuroD,Mash1/Zash1a and Pax6).further topological correspondences are seen in the expression of LIM and homeobox genes,such as Lhx6/7,Tbr2 and *** this analysis is extended to gamma-aminobutyric acid/glutamic acid decarboxylase(GABA/GAD)cell patterns during this critical time window,an astonishing degree of similarity between the two species is again seen,for example regarding the presence of GABA/GAD cells in the subpallium,with the pallium only starting to be invaded by such cells from the ***,the expression of proneural and other genes correlates with GABA cell patterns(***1/Zash1a gene expression in GABA-positive and Neurogenin1/NeuroD in GABA-negative telencephalic regions)in mice and *** from additional vertebrates,such as Xenopus,are also highly consistent with this ***,the vertebrate forebrain appears to undergo a phylotypic stage of secondary neurogenesis,characterized by regionally separated GABAergic(inhibitory)versus glutamatergic(excitatory)cell production sites,which are obscured later in development by tangential *** period is highly advantageous for molecular neuroanatomical cross-species comparisons.

关键词： basal ganglia cortex subpallium tangential migration gamma-aminobutyric acid GABA.

An unexpected cellular fountain of youth:platelets provide factors rejuvenating brain functions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2024年第1期9卷 16-18页

作者： Harald f.Langer Department of Cardiology AngiologyHaemostaseology and Medical Intensive CareUniversity Medical Centre MannheimMedical Faculty MannheimHeidelberg UniversityMannheimGermany German Centre for Cardiovascular Research(DZHK) Partner Site Heidelberg/MannheimMannheimGermany European Center for Angioscience Medical Faculty MannheimHeidelberg UniversityMannheimGermany Cardiovascular systems biology Medical Clinic IUniversity Heart Center LübeckLübeckGermany

In a recent manuscript published in Nature,Schroer et *** that platelets and in particular platelet derived Pf-4(CXCL4)are a novel factor,which can rejuvenate the mammalian neuronal system.1 These findings have the potential to trigger an entire new field of research opening new platelet-derived candidate effector molecules for supporting regeneration.

关键词： supporting platelets finding

Optimal Hybrid Deep Learning Enabled Attack Detection and Classificationin IoT Environment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第4期75卷 99-115页

作者： fahad f.Alruwaili College of Computing and Information Technology Shaqra UniversitySharqaSaudi Arabia

The Internet of Things (IoT) paradigm enables end users to accessnetworking services amongst diverse kinds of electronic devices. IoT securitymechanism is a technology that concentrates on safeguarding the devicesand networks connected in the IoT environment. In recent years, false DataInjection Attacks (fDIAs) have gained considerable interest in the IoT *** compromise the devices connected to the networkand inject the data. Such attacks on the IoT environment can result in a considerableloss and interrupt normal activities among the IoT network *** fDI attacks have been effectively overcome so far by conventional threatdetection techniques. The current research article develops a Hybrid DeepLearning to Combat Sophisticated false Data Injection Attacks detection(HDL-fDIAD) for the IoT environment. The presented HDL-fDIAD modelmajorly recognizes the presence of fDI attacks in the IoT *** HDL-fDIAD model exploits the Equilibrium Optimizer-based featureSelection (EO-fS) technique to select the optimal subset of the ***, the Long Short Term Memory with Recurrent Neural Network(LSTM-RNN) model is also utilized for the purpose of classification. At last,the Bayesian Optimization (BO) algorithm is employed as a hyperparameteroptimizer in this study. To validate the enhanced performance of the HDLfDIADmodel, a wide range of simulations was conducted, and the resultswere investigated in detail. A comparative study was conducted between theproposed model and the existing models. The outcomes revealed that theproposed HDL-fDIAD model is superior to other models.

关键词： false data injection attacks hyperparameter optimizer deep learning feature selection IoT security

function of seminal vesicles and their role on male fertility

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2001年第4期3卷 251-258页

作者： Gustavo f.Gonzales Department of Physiological Sciences Faculty of Sciences and Philosophy and Instituto de Invertigaciones de la Altura Universidad Peruana Cayetano Heredia Lima Peru

The present review has been designed to update the recent developments on the function of seminal vesicles andtheir role on male fertility. It is indicated that the true corrected fructose level is a simple method for the assessment ofthe seminal vesicular function. Measurement of seminal fructose used universally as a marker of the seminal vesiclefunction is not an appropriate approach due to its inverse relationship with the sperm count. The true corrected fructosedefined as [log. motile sperm concentration] multiplied by [seminal fructose concentration] has been shown to be abetter marker of the seminal vesicle function. Seminal vesicular secretion is important for semen coagulation, sperm motility, and stability of sperm chromatinand suppression of the immune activity in the female reproductive tract. In conclusion, the function of seminal vesicle is important for fertility. Parameters as sperm motility, sperm chro-matin stability, and immuno-protection may be changed in case of its hypofunction. (Asian J Androl 2001 Dec; 3:251 -258)

关键词： seminal vesicles male fertility male infertility true corrected fructose

Varieties for Cohomology with Twisted Coefficients

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 1999年第1期15卷 81-92页

作者： Jon f.Carlson Department of Mathemtics University of GeorgiaAthensGA 30602 USA

Let G be a finite group and k a field of characteristic p>*** this paper we consider the support variety for the cohomology module ExtkG*（M,N） where M and N are *** is the subvariety of the maximal ideal spectrum of H*（G,k） of the annihilator of the cohomology module. for modules in the principal block we show that that the variety is contained in the intersections of the varieties of M and N and the difference between the that intersection and the support variety of the cohomology module is contained in the group theoretic *** other blocks a new nucleus is defined and a similar theorem is *** in the case of modules in a nonprincipal block several new difficulties are highlighted by some examples.

关键词： Group Cohomology Support varieties Cohomological varieties Annihilators of cohomology

A Model Transformation Approach for Detecting Distancing Violations in Weighted Graphs

在线全文

学校读者我要写书评

暂无评论

Computer Systems Science & Engineering 2021年第1期36卷 13-39页

作者： Ahmad f.Subahi Department of Computer Science University College of Al JamoumUmm Al Qura UniversityMakkah21421Saudi Arabia

This work presents the design of an Internet of Things(IoT)edge-based system based on model transformation and complete weighted graph to detect violations of social distancing measures in indoor public *** sensor network based on Bluetooth Low Energy is introduced as the infrastructure of the proposed design.A hybrid model transformation strategy for generating a graph database to represent groups of people is presented as a core middleware layer of the detecting system’s proposed architectural design.A Neo4j graph database is used as a target implementation generated from the proposed transformational system to store all captured real-time IoT data about the distances between individuals in an indoor area and answer user predefined queries,expressed using Neo4j Cypher,to provide insights from the stored data for decision *** proof of concept,a discrete-time simulation model was adopted for the design of a COVID-19 physical distancing measures case study to evaluate the introduced system ***-one weighted graphs were generated randomly and the degrees of violation of distancing measures were *** experimental results demonstrate the capability of the proposed system design to detect violations of COVID-19 physical distancing measures within an enclosed area.

关键词： Model-driven engineering(MDE) Internet-of-Things(IoTs) model transformation edge computing system design Neo4j graph databases

Numerical Study of flow and Gas Diffusion in the Near-Wake behind an Isolated Building

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2009年第6期26卷 1241-1252页

作者： Mohamed f.YASSIN Department of Environmental Technology Management College for WomenKuwait University P.O.Box 5969KuwaitSafat 13060Kuwait faculty of Engineering Assiut UniversityAssiut-71516Egypt

To assist validation of the experimental data of urban pollution dispersion, the effect of an isolated building on the flow and gaseous diffusion in the wake region have been investigated numerically in the neutrally stratified rough-walled turbulent boundary layer. Numerical studies were carried out using Computational fluid Dynamics （CfD） models. The CfD models used for the simulation were based on the steady-state Reynolds-Average Navier-Stoke equations （RANS） with κ-ε turbulence models; standard κ-ε and RNG κ-ε models. Inlet conditions and boundary conditions were specified numerically to the best information available for each fluid modeling simulation. A gas pollutant was emitted from a point source within the recirculation cavity behind the building model. The accuracy of these simulations was examined by comparing the predicted results with wind tunnel experimental data. It was confirmed that simulation using the model accurately reproduces the velocity and concentration diffusion fields with a fine-mish resolution in the near wake region. Results indicated that there is a good agreement between the numerical simulation and the wind tunnel experiment for both wind flow and concentration diffusion. The results of this work can help to improve the understanding of mechanisms of and simulation of pollutant transport in an urban environment.

关键词： atmospheric turbulence CfD model isolated building pollutant dispersion

Improving weld formability by a novel dual-rotation bobbin tool friction stir welding

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第1期34卷 135-139页

作者： f.f.Wang W.Y.Li J.Shen Q.Wen J.f.dos Santos State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics China Academy of Launch Vehicle Technology Beijing Institute of Astronautical Systems Engineering

A novel dual-rotation bobbin tool friction stir welding （DBT-fSW） was developed, in which the upper shoulder （US） and lower shoulder （LS） have different rotational speeds. This process was tried to weld 3.2 mm thick alunlinum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formabiliW. Experimental results show that compared to conven- tional bobbin tool friction stir welding, the DBT-fSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-fSW process.

关键词： Bobbin tool friction stir welding Dual rotation Material flow Microstructure Microhardness