检索结果-南通市图书馆

A MATHEMATICAL MODEL FOR THE DEPLETION OF FORESTRY RESOURCES DUE TO POPULATION AND POPULATION PRESSURE AUGMENTED INDUSTRIALIZATION

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International journal of Modeling, Simulation, and Scientific Computing 2014年第1期5卷 186-201页

作者： A.K.MISRA KUSUM LATA j.b.shukla Department of Mathematics Faculty of Science Banaras Hindu UniversityVaranasi-221005India bIT BIIFR&DBhabha Group of Institutions Kanpur(Rural)-209204India

In this paper,a nonlinear mathematical model is proposed and analyzed to study the depletion of forestry resources caused simultaneously by population and population pressure augmented *** control of population pressure,using economic efforts is also considered in the modeling *** is assumed that cumulative biomass density of forestry resources and the density of population follow logistic *** is further assumed that the density of population and the level of industrialization increase as the cumulative biomass density of forestry resources *** cumulative density of economic efforts,which are applied to control the population pressure,is considered to be proportional to the population *** model analysis shows that as the population pressure increases,the level of industrialization increases leading to decrease in the cumulative biomass density of forestry *** is found that if population pressure is controlled by using some economic efforts,the decrease in cumulative biomass density of forestry resources can be made much less than the case when no control is *** is also noted that if the population pressure augmented industrialization increases without control,the forestry resources may become extinct.

关键词： Mathematical model forestry resources population pressure industrialization economic efforts stability

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

铁磁流体润滑理论

润滑与密封 1990年第2期 65-68页

作者： j.b.shukla D.KUMAR 许孙曲

考虑到颗粒转动作用,推导在横向外加磁场存在下,决定铁磁流体薄膜中压力的雷诺方程一般式。此方程被用于研究外加磁场和布朗弛豫时间参数对无限长挤压薄膜轴承和滑动轴承的支承特性的影响。

关键词：铁磁流体雷诺方程外加磁场一般式运动方程薄膜轴承滑动轴承

EFFECTS OF POPULATION AND INDUSTRIALIZATION ON THE DEGRADATION OF bIOMASS AND ITS REGENERATION bY AFFORESTATION: A MATHEMATICAL MODEL

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

生物数学学报 1988年第1期 1-9页

作者： j.b.shukla V.N.Pal O.P.Misra Manju Agarwal Ajai shukla Departmant of Mathematics I.I.T Kanpur India Departmant of Applied Science Institute of Eng.and Techn Lucknow Nodal Centre for National Technical Manpower Information System I. I. T. Kanpur India

The bio-mass(Food, Fodder and Forestry, etc. ) in a habitat has beencontinuously depleting due to rapid industrialization and over-population leadingto various kinds of undesirable effects on our environment and on land masscausing deep concern to planners and management experts. In this paper, therefore, a mathematical model for degradation of bio-massis presented to study the effects of industrialization and associated growth ofpopulation, It is shown that with the increase in the levels of these factors,the bio-mass resource may not last long. It has also been pointed out mathematicallythat the level of the biomass can be maintained at desired equilibrium level bya suitable afforestation programme.

关键词： A MATHEMATICAL MODEL EFFECTS OF POPULATION AND INDUSTRIALIZATION ON THE DEGRADATION OF bIOMASS AND ITS REGENERATION bY AFFORESTATION

Water Vapor Information from Satellite and Its Applications

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第1期41卷 188-189页

作者： b.j.SOHN School of Earth and Environmental Sciences Seoul National UniversitySeoul 08826Korea

Water vapor is a critical component of the hydrological cycle because it plays a vital role in transporting water from one part of the cycle to *** vapor evaporated from surfaces such as oceans,lakes,and rivers conden... 详细信息

关键词： motion oceans lakes

Compressive property and energy absorption characteristic of interconnected porous Mg-Zn-Y alloys with adjusting Y addition

在线全文

学校读者我要写书评

暂无评论

journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： j.A.Liu S.j.Liu b.Wang W.b.Sun X.j.Liu Z.W.Han College of Materials Science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China Weihai Institute for bionics-jilin University Weihai 264205PR China

In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption *** characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second *** tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous *** experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second *** the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),W-phase(Mg_(3)Zn_(3)Y_(2)),and LPSO phase(Mg_(12)ZnY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 Mj/m^(3)to 10.97 Mj/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second ***,the average energy absorption efficiency is independent of the Y *** addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing *** compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the *** deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： Porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

Iron regulatory protein 1: the deadly switch of ferroptosis

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第3期19卷 477-478页

作者： Daniel A.bórquez Pamela j.Urrutia Center for biomedical Research Faculty of MedicineUniversidad Diego PortalesSantiagoChile Institute of Nutrition&Food Technology(INTA) Universidad de ChileSantiagoChile Geroscience Center for brain Health and Metabolism SantiagoChile

Ferroptosis,an iron-dependent cell death:Ferroptosis is a type of regulated necrosis,characterized by redox-active iron accumulation and increased free radical production derived by Fenton chemistry,that triggers oxidation of polyunsaturated fatty acids in phospholipids,loss of cellular membranes integrity,and leakage of intracellular contents.

关键词： integrity switch Iron

Thermo-kinetic characteristics on stabilizing hetero-phase interface of metal matrix composites by crystal plasticity finite element method

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2024年第2期169卷 53-67页

作者： Y.b.Zhang S.j.Song F.Liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Analytical&Testing Center Northwestern Polytechnical UniversityXi’an 710072China

Using dislocation-based constitutive modeling in three-dimension crystal plasticity finite element(3D CPFE)simulations,co-deformation and instability of hetero-phase interface in different material systems were herein studied for polycrystalline metal matrix composites(MMCs).Local stress and strain fields in two types of 3layer MMCs such as fcc/fcc Cu-Ag and fcc/bcc Cu-Nb have been predicted under simple compressive ***,more severe strain-induced interface instability can be observed in the fcc/bcc systems than in the fcc/fcc systems upon refining to metallic nanolayered composites(MNCs).by detailed analysis of stress and strain localization,it has been demonstrated that the interface instability is always accompanied by high-stress concentration,i.e.,thermodynamic characteristics,or high strain prevention i.e.,kinetic characteristics,at the hetero-phase *** then follows that the thermodynamic driving forceG and the kinetic energy barrier Q during dislocation and shear banding can be adopted to classify the deformation modes,following the so-called thermo-kinetic *** by inserting a high density of high-energy interfaces into the Cu-Nb composites,such thermo-kinetic integration at the hetero-phase interface allows a successful establishment of MMCs with the high△G-high Q deformation mode,which ensures high hardening and uniform strain distri-bution,thus efficiently suppressing the shear band,stabilizing the hetero-phase interface,and obtaining an exceptional combination in strength and *** hetero-phase interface chosen by a couple of thermodynamics and kinetics can be defined as breaking the thermo-kinetic correlation and has been proposed for artificially designing MNCs.

关键词： Thermodynamics and kinetics Physics-based constitutive modeling Hetero-phase interface Crystal plasticity finite element

Semi-analytical investigation of heat transfer in a porous convective radiative moving longitudinal fin exposed to magnetic field in the presence of a shape-dependent trihybrid nanofluid

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) 2024年第1期45卷 197-216页

作者： C.G.PAVITHRA b.j.GIREESHA M.L.KEERTHI Department of PG Studies and Research in Mathematics Kuvempu UniversityShankaraghatta 577451India Department of Mathematics and Statistics M.S.Ramaiah University of Applied SciencesBengaluru 560058India

The thermal examination of a non-integer-ordered mobile fin with a magnetism in the presence of a trihybrid nanofluid(Fe_3O_4-Au-Zn-blood) is carried out. Three types of nanoparticles, each having a different shape, are considered. These shapes include spherical(Fe_3O_4), cylindrical(Au), and platelet(Zn) configurations. The combination approach is utilized to evaluate the physical and thermal characteristics of the trihybrid and hybrid nanofluids, excluding the thermal conductivity and dynamic viscosity. These two properties are inferred by means of the interpolation method based on the volume fraction of nanoparticles. The governing equation is transformed into a dimensionless form, and the Adomian decomposition Sumudu transform method(ADSTM) is adopted to solve the conundrum of a moving fin immersed in a trihybrid nanofluid. The obtained results agree well with those numerical simulation results, indicating that this research is reliable. The influence of diverse factors on the thermal overview for varying noninteger values of γ is analyzed and presented in graphical representations. Furthermore, the fluctuations in the heat transfer concerning the pertinent parameters are studied. The results show that the heat flux in the presence of the combination of spherical, cylindrical, and platelet nanoparticles is higher than that in the presence of the combination of only spherical and cylindrical nanoparticles. The temperature at the fin tip increases by 0.705 759% when the value of the Peclet number increases by 400%, while decreases by 11.825 13% when the value of the Hartman number increases by 400%.

关键词： convection radiation moving longitudinal fin Adomian decomposition Sumudu transform method(ADSTM) trihybrid nanofluid magnetic field

Long-term monitoring of cycles in Clethrionomys rutilus in the Yukon boreal forest

在线全文

学校读者我要写书评

暂无评论

Integrative Zoology 2024年第1期19卷 27-36页

作者： Charles j.KREbS Alice j.KENNEY b.Scott GILbERT Rudy bOONSTRA Department of Zoology University of British ColumbiaVancouverBritish ColumbiaCanada Renewable Resources Management Program Yukon UniversityWhitehorseYukonCanada Department of biological Sciences University of Toronto ScarboroughTorontoOntarioCanada

baseline studies of small rodent populations in undisturbed ecosystems are *** report here 50 years of mon-itoring and experimentation in Yukon of a dominant rodent species in the North American boreal forest,the red-backed vole Clethrionomys *** voles breed in summer,weigh 20–25 g,and reach a maximum density of 20 to 25 per *** populations have shown consistent 3–4-year cycles for the last 50 years with the only change being that peak densities averaged 8/ha until 2000 and 18/ha since that *** the last 25 years,we have measured food resources,predator numbers,and winter weather,and for 1-year social interactions,to estimate their contribution to changes in the rate of summer increase and the rate of overwinter *** these potential limiting factors could contribute to changes in density,and we measured their relative contributions statistically with multiple *** rate of winter decline in density was related to both food supply and winter *** rate of summer increase was related to summer berry crops and white spruce cone *** measure of predator numbers was related to winter or summer changes in vole *** was a large signal of climate change effects in these *** is no density dependence in summer population growth and only a weak one in winter population *** of our results provide a clear understanding of what generates 3–4-year cycles in these voles,and the major missing piece may be an understanding of social interactions at high density.

关键词： boreal forest climate change density dependence population cycles predation winter severity