检索结果-南通市图书馆

Microstructure and Property Relationships in Resistance Spot Weld between 7114 Interstitial Free Steel and 304 Austenitic Stainless Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2006年第3期22卷 375-381页

作者： Ahmet Hasanba■o■lu Ramazan Kaar Department of Metal Education Karabük Technical Education Faculty Karabük 78100 Turkey

Due to the differences in physical, chemical and mechanical properties of the base metals, the resistance spot welding of dissimilar materials is generally more challenging than that of similar materials. The influence of the primary welding parameters affecting the heat input such as peak current on the morphology, microhardness, and tensile shear load bearing capacity of dissimilar welds between 304 grades austenitic and 7114 grade interstitial free steel has been investigated in this study. The optimum welding parameters producing maximum joint strength were established at a peak current of 9 kA, where the electrode force is kept 6×10^-5 Pa and weld time is kept constant 17 cycles, respectively. The primary cause of weakening the weldment is identified as the excessive grain growing region of heat affected zone （HAZ） in case of 7114 grade interstitial free steel.

关键词： Resistance spot weld Interstitial free steel Austenitic stainless steel

Effect of Under Connected Plates on the Hydrodynamic Efficiency of the Floating Breakwater

在线全文

学校读者我要写书评

暂无评论

China ocean Engineering 2014年第3期28卷 349-362页

作者： A.S.Koraim o.S.Rageh Water and Water Structure Engineering Department Faculty of EngineeringZagazig University Irrigation and Hydraulics Department Faculty of Engineering El-Mansoura University

In this paper, the hydrodynamic efficiency of a floating breakwater system is experimentally studied by use of physical models. Regular waves with wide ranges of wave heights and periods are tested. The efficiency of the breakwater is presented as a function of the wave transmission, reflection, and energy dissipation coefficients. Different parameters affecting the breakwater efficiency are investigated, e.g. the number of the under connected vertical plates, the length of the mooring wire, and the wave length. It is found that, the transmission coefficient kt decreases with the increase of the relative breakwater width B/L, the number of plates n and the relative wire length l/h, while the reflection coefficient kr takes the opposite trend. Therefore, it is possible to achieve kt values smaller than 0.25 and kr values larger than 0.80 when B/L is larger than 0.25 for the case of l/h-1.5 and n=4. In addition, empirical equations used for estimating the transmission and reflection coefficients are developed by using the dimensionless analysis, regression analysis and measured data and verified by different theoretical and experimental results.

关键词： floating breakwaters vertical plates regular waves transmission reflection energy dissipation

Weathering reflected by the chemical composition of alluvial soils from the Zeya and Selemdzha river valleys

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2018年第5期61卷 604-613页

作者： o.A.SoRoKINA M.N.GYSEV Institute of Geology and Nature Management Far East Branch Russian Academy of Sciences

The paper examines the chemical composition of alluvial soils from the Zeya and Selemdzha River valleys, one of the branch rivers in the Amur River basin. It has been established that the compositions of these soils are characterized by a relative shortage of practically all analyzed macro-and microelements as compared with UCC(upper continental crust) and PAAS(postArhean Australian average shale) compositions. The chemical composition of alluvial soils approximates that of the soils in NE China and Korea due to similar climatic and geographic conditions. on the basis of relationships between major and trace elements and peculiarities of trace elements concentration it is shown that the alluvial soils in the middle reaches of the Zeya River were formed by the sources largely transformed by chemical weathering processes. By comparison, the soils in the Selemdzha River and lower reaches of the Zeya River(below the Selemdzha River mouth) are dominated by material to a large degree reworked by the physical processes rather than chemical ones. This inference conforms with specific geological settings of the water-collector.

关键词： Alluvial soils Weathering indices Amur Zeya

Thermal efficiency of the principal greenhouse gases

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第1期24卷 195-200页

作者： A.Y.Galashev o.R.Rakhmanova Institute of Industrial Ecology Ural Branch Russian Academy of Sciences Yekaterinburg 620990 Russia

Atmospheric gases are ranked according to the efficiency with which they absorb and radiate longwave radiation. The open international HITRAN database of gaseous absorption lines of high resolution together with inverse Fourier transform were used. The autocorrelation functions of the total dipole moment of the basic greenhouse gases molecules such as H2 o,Co2, o3, N2 o, and CH4 were obtained. Absorption coefficient spectra and emission power spectra of infrared radiation of these gases were calculated. Analysis of the emissive ability of all gases under consideration was carried out. Compared to Co2, all the gases under investigation have more effective emission except ozone. An efficiency criterion of IR absorption and emission is defined and is calculated for each studied gas, and the gases are ranked accordingly as follows（from strong to weak）： H2 o, CH4, Co2, N2 o, and o3.

关键词： greenhouse gases absorption and emission spectra efficiency criterion

The electrochemical detection of bioterrorism agents: a review of the detection, diagnostics, and implementation of sensors in biosafety programs for Class A bioweapons

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2021年第1期7卷 21-39页

作者： Connor o’Brien Kathleen Varty Anna Ignaszak Department of Chemistry University of New Brunswick30 Dineen DriveFrederictonNB E3B 5A3Canada

During the past year,disease has shown us the iron grip it can hold over a population of *** systems can be overwhelmed,economies can be brought into recession,and many people can be harmed or *** weaponized,diseases can be manipulated to create a detriment to health while becoming an economic burden on any *** is consequently prudent that easy detection of bioweapons is available to governments for protecting their *** sensing displays many distinct advantages,such as its low limit of detection,low cost to run,rapid generation of results,and in many instances *** therefore present a wide array of electrochemical sensing platforms currently being fabricated,a brief summary of Class A bioweapons,and the potential future of bioweapon detection and biosafety.

关键词： electrochemical instance programs

Pavement sustainability index for highway infrastructures： A case study of Maryland

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 Structural and Civil Engineering 2018年第2期12卷 192-200页

作者： Stella o. oBAZEE-IGBINEDIoN oludare oWoLABI Montgomery County Department of Transportation 100 Edison Park Drive Gaithersburg MD 20878 USA Department of Civil Engineering Morgan State University 1700 East Cold Spring Lane Baltimore MD 21251 USA

Pavement deterioration creates conditions that undermine their performances, which gives rise to the need for maintenance and rehabilitation. This paper develops a mathematical multi-linear regression analysis （MLRA） model to determine a pavement sustainability index （PSTI） as dependent variable for flexible pavements in Maryland. Four categories of pavement performance evaluation indicators are subdivided into seven pavement condition indices and analyzed as independent variables for each section of pavement. Data are collected from five different roadways using field evaluations and existing database. Results indicate that coefficient of determination （R^2） is correlated and significant, R^2 = 0.959. of the seven independent variables, present serviceability index （PSI） is the most significant with a coefficient value of 0.032, present serviceability rating （PSR） coefficient value=0.028, and international roughness index （IRI） coefficient value = -0.001. Increasing each unit value of coefficients for PSI and PSR would increase the value of PSTI; thereby providing a more sustainable pavement infrastructure; which explains the significance of the model and why IR/ will most likely impact environmental, economic and social values.

关键词： pavement indices sustainability pavement performance flexible pavements

Dynamics of a fluid-filled curvilinear pipeline

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

Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 905-922页

作者： V.A.RUKAVISHNIKoV o.P.TKACHENKo Computing Center of Far-Eastern Branch Russian Academy of Sciences

A mathematical model is presented, and numerical experiments are performed to describe the mechanics of the slow movement of a pipeline. The problem reduction algorithm to one-dimensional formulation is offered. Results of numerical experiment for the model problem are adduced. The proposed mathematical model is found to adequately describe the dynamics of known phenomena of pipes. The cross-sections of the extended curvilinear thin-walled pipeline are numerically demonstrated to experience warping, which has experimental confirmation in the literature.

关键词： bent pipeline numerical experiment hydroelasticity shell theory

Viscoelastic modeling of the diffusion of polymeric pollutants injected into a pipe flow

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第2期29卷 166-178页

作者： T.Chinyoka o.D. Makinde Center for Research in Computational and Applied Mechanics University of Cape Town Institute for Advanced Research in Mathematical Modeling and Computations Cape Peninsula University of Technology

This study focuses on the transient analysis of nonlinear dispersion of a polymeric pollutant ejected by an external source into a laminar pipe flow of a Newtonian liquid under axi-symmetric *** influence of density variation with pollutant concentration is approximated according to the Boussinesq approximation and the nonlinear governing equations of momentum,pollutant concentration are obtained together with and oldroyd-B constitutive model for the polymer *** problem is solved numerically using a semi-implicit finite difference *** are presented in graphical form for various parameter values and given in terms of fluid velocity,pollutant concentration,polymer stress components,skin friction and wall mass transfer *** model can be a useful tool in understanding the dynamics of industrial pollution situations arising from improper discharge of hydrocarbon pollutants into,say,water *** model can also be quite useful for available necessary early warning methods for detecting or predicting the scale of pollution and hence help mitigate related damage downstream by earlier instituting relevant decontamination measures.

关键词： Axi-symmetric flow·Polymeric pollutant dispersion·oldroyd-B model Buoyancy forces·Semi-implicit finite difference method

Major cereal carbohydrates in relation to intestinal health of monogastric animals:A review

在线全文

学校读者我要写书评

暂无评论

Animal Nutrition 2019年第4期5卷 331-339页

作者： Tolulope o.Adebowale Kang Yao Abimbola o.oso University of the Chinese Academy of Sciences Beijing100008China Key Laboratory of Agro-Ecological Processes in Subtropical Region Institute of Subtropical AgricultureChinese Academy of SciencesHunan Provincial Engineering Research Center for Healthy Livestock and Poultry ProductionScientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-CentralMinistry of AgricultureChangsha410125China Department of Animal Nutrition Federal University of AgricultureAbeokutaPMB 2240Nigeria

Type,quality,and origin of cereals in diets of poultry and pigs could influence gut microbes and affect their diversity and function,thereby impacting the intestinal function of the monogastric *** this review,we focus on the major carbohydrates in cereals that interact directly with gut microbes and lead to the production of key metabolites such as short-chain fatty acids(SCFA),and discuss how cereal fiber impact intestinal health of poultry and *** overview of how the cereals and cereals-derived carbohydrates such as beta-glucans,resistant starch,cellulose,and arabinoxylans could promote intestinal health and reduce the use of in-feed antibiotics in animal production are *** metabolic pathway utilized by microbes and the mechanism of action underlying the produced SCFA on intestinal health of monogastric animals is also discussed.

关键词： Arabinoxylans Beta-glucans Resistant starch Cellulose SCFA Intestinal health