检索结果-南通市图书馆

ON A GENERALIZED GEOMETRIC CONSTANT AND SUFFICIENT CONDITIONS FOR NORMAL STRUCTURE IN BANACH SPACES

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2017年第5期37卷 1209-1220页

作者： mina DINARVAND Faculty of Mathematics K.N.ToosiUniversity of TechnologyP.O.Box 16315-1618TehranIran

In this paper, we introduce a new geometric constant C;（a, X） of a Banach space X, which is closely related to the generalized von Neumann-Jordan constant and analyze some properties of the constant. Subsequently, we present several sufficient conditions for normal structure of a Banach space in terms of this new constant, the generalized James constant, the generalized Garc′?a-Falset coefficient and the coefficient of weak orthogonality of Sims. Our main results of the paper generalize some known results in the recent literature.

关键词： uniform normal structure generalized Garc′?a-Falset coefficient coefficient of weak orthogonality constant CN Jp(a,X) generalized James constant

在线全文

学校读者我要写书评

暂无评论

海洋与气候变化以及基于自然的解决方案

生态文明新时代 2024年第1期 126-128页

作者：米娜·艾普斯世界自然保护联盟 IUCN保护行动中心

众所周知,海洋为人类作出了巨大贡献,海洋对人类福祉至关重要,它承载了90%以上的货物运输和相关服务,吸收了全球90%多余的热量,大气中的二氧化碳排放量约有四分之一被海洋吸收。但是,随着海洋酸化的加剧,海洋的这种碳吸收能力无法持续,... 详细信息

众所周知,海洋为人类作出了巨大贡献,海洋对人类福祉至关重要,它承载了90%以上的货物运输和相关服务,吸收了全球90%多余的热量,大气中的二氧化碳排放量约有四分之一被海洋吸收。但是,随着海洋酸化的加剧,海洋的这种碳吸收能力无法持续,海水将无法吸收更多的二氧化碳。目前,人类活动正给海洋生境带来巨大压力,海洋正逐渐变暖,海水酸度已经上升30%,最终将导致海洋生物难以生存。同时,海水中的氧含量平均减少了2%,这一看似微小的数字背后蕴藏着巨大的地区差异,某些海域海水的氧含量已经减少30%,我们能直观了解森林树木的变化,但无法直观感受到海水含氧量与日俱减。因此,大量海洋生物不断发生迁移。

关键词：直观感受二氧化碳排放量货物运输人类福祉海洋酸化气候变化海洋生物碳吸收

华北局地大暴雨过程中多个β中尺度对流系统发生发展对比分析

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

气象 2024年第2期50卷 181-194页

作者：徐姝易笑园熊明明孙密娜林晓萌天津市气象台天津300074 中国气象局水文气象重点开放实验室南京210024 天津市气候中心天津300074

利用常规地面高空观测、多普勒雷达、风廓线、VDRAS(Variational Doppler Radar Analysis System)和NCEP再分析资料,对2018年8月5—6日副热带高压(以下简称副高)控制下华北一次局地大暴雨过程中多个β中尺度对流系统触发和发展机制进行... 详细信息

利用常规地面高空观测、多普勒雷达、风廓线、VDRAS(Variational Doppler Radar Analysis System)和NCEP再分析资料,对2018年8月5—6日副热带高压(以下简称副高)控制下华北一次局地大暴雨过程中多个β中尺度对流系统触发和发展机制进行了分析。结果表明:这次大暴雨发生在副高控制下,处于高温、高湿气团中,大气层结极不稳定。暴雨由多个相继发展的中尺度对流系统造成,分别是太行山迎风坡上西南—东北向、华北平原地区保定一带南北向、保定至霸州附近西南—东北向和以雄安新区为中心东西向原地生消的准静止MCS-Ⅰ、MCS-Ⅱ、MCS-Ⅲ和MCS-Ⅳ,均属于β中尺度。在相似的环境中,不同中尺度对流系统触发机制有较大差异,太行山迎风坡上的MCS-Ⅰ是由近地层偏东暖湿气流在迎风坡与山风形成的辐合抬升触发;由辐射差异和前期强降水形成的局地冷池受MCS-Ⅰ影响再次加强后,其出流与环境风形成的两条地面辐合线分别触发了MCS-Ⅱ和MCS-Ⅲ,并组织对流沿辐合线呈带状发展;而超低空偏东风增强叠加冷池出流在地形抬升作用下促使沿山暖湿气团进一步抬升,使得原本消亡的MCS-Ⅰ再次重建。MCS-Ⅳ发展最旺盛、持续时间最长,是大暴雨中心的直接制造者,一方面MCS-Ⅱ与MCS-Ⅲ、MCS-Ⅰ与MCS-Ⅳ的两次合并过程,是MCS-Ⅳ增强、持久的重要原因;另一方面边界层偏东风急流为MCS-Ⅳ的发展提供了水汽和不稳定能量等有利条件,同时推动其左前方中尺度涡旋的发展,导致MCS-Ⅳ所在地的气旋性涡度大大增加,加强了以急流轴为中心的垂直次级环流发展,造成MCS-Ⅳ的发展维持,形成华北平原地区以雄安新区为中心的东西向大暴雨带。

关键词：准静止中尺度对流系统对流单体合并冷池地面辐合线中尺度边界层急流中尺度涡旋

Spatial patterns and secular trends in human leishmaniasis incidence in Morocco between 2003 and 2013

在线全文

学校读者我要写书评

暂无评论

Infectious Diseases of Poverty 2016年第1期5卷 404-416页

作者： mina Sadeq Environmental Epidemiology Unit National Institute of HygieneMinistry of Health27 Avenue Ibn BattutaBP 769 RabatMorocco

Background:Few studies on spatial patterns or secular trends in human leishmanias have been conducted in *** study aimed to examine spatial patterns and trends associated with the human leishmaniasis incidence rate(HLIR)at the province/prefecture level between 2003 and 2013 in ***:Only the available published country data on the HLIR between 2003 and 2013,from the open access files of the Ministry of Health,were *** trends were examined using Kendall’s rank *** exploratory spatial data analysis was also conducted to examine the spatial autocorrelation(Global Moran’s I and local indicator of spatial association[LISA]),and spatial diffusion at the province/prefecture *** influence of various covariates(poverty rate,vulnerability rate,population density,and urbanization)on the HLIR was tested via spatial regression(ordinary least squares regression).Results:At the country level,no secular variation was *** annual incidence rate estimates were 13 per 100000 population(95%CI=12.9–13.1)for cutaneous leishmaniasis(CL)and 0.4 per 100000 population(95%CI=0.4–0.5)for visceral leishmaniasis(VL).The available data on HLIR were based on combined CL and VL cases,however,as the CL cases totally outnumbered the VL ones,HLIR may be considered as CL incidence *** the provincial level,a secular increase in the incidence rate was observed in Al Hoceima(P=0.008),Taounate(P=0.04),Larache(P=0.002),Tétouan(P=0.0003),Khenifra(P=0.008),Meknes(P=0.03),and El Kelaa(P=0.0007),whereas a secular decrease was observed only in the Chichaoua province(P=0.006).Even though increased or decreased rate was evident in these provinces,none of them showed clustering of leishmaniasis *** spatial clusters of high leishmaniasis incidence were located in the northeastern part of Morocco,while spatial clusters of low leishmaniasis incidence were seen in some northwestern and southern parts of Morocco;there was spatial randomness i

关键词： Human leishmaniasis Epidemiology Incidence rates Spatial patterns Secular trends Morocco

Evolution of seasonal land surface temperature trend in pond-breeding newt(Neurergus derjugini)in western Iran and eastern Iraq

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

Ecological Processes 2023年第1期12卷 217-231页

作者： Peyman Karami Sajad Tavakoli mina Esmaeili Department of Environmental Sciences Faculty of Natural Resources and Environment SciencesMalayer UniversityMalayerIran Department of Environmental and Forest Science Faculty of Natural Resources and EnvironmentScience and Research BranchIslamic Azad UniversityTehranIran Department of Biology Faculty of ScienceRazi UniversityKermanshahIran

Background Temperature,as one of the effective environmental stimuli in many aspects of species life and ecosystems,can affect amphibians in many *** and predicting temperature change and its possible effects on the habitat suitability and movements of amphibians have led many researchers to use climate change scenarios and species distribution models(SDMs).One of the important remote-sensing products that received less attention of conservation biologists is the land surface temperature(LST).Due to the small difference between LST and air temperature,this component can be used to investigate and monitor the daily and seasonal changes of *** study aims to investigate the seasonal trend of LST in the habitat suitability and connectivity of the critically endangered newt(Neurergus derjugini)in its small distribution range,using the MODIS LST time series(2003 to 2021)and with the help of SDMs,Mann–Kendall(MK)and Pettitt non-parametric *** In the last decade,the increasing trend of LST versus its decreasing trends is *** on MK and Pettitt tests,in the winter and spring,with the decrease in latitude of 35.45°and increase in longitude of 46.14°,the core populations which are located in the southeast have experienced an increase in *** the period time of breeding and overwintering,the continuity of winter and spring can be effective on the survival of adult newts as well as larvae in the *** with the highest current flow between core populations in the winter and summer are the most likely to be *** the level of habitat,the increase in LST is proportional to the trend of thermal landscape changes,and all seasons have had an increase in LST,but in winter and summer,the largest area of the habitat has been *** continuing the current trend,many high-altitude southern habitats in Iran will be endangered,and the species will be at risk of local *** The increasing tre

关键词： Seasonal change Local extinction Climate refuge Amphibian

同方期刊数据库

Correlation between the molecular structure and transcis isomerization characteristics of azobenzenes

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2011年第12期54卷 1955-1961页

作者： HAN mina HONDA Takumu Department of Chemistry and Department of Electronic Chemistry Tokyo Institute of Technology

Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and trans → cis isomerization characteristics of azobenzenes. A blue shift in π-π absorption band of ortho-alkylated azobenzenes （1o and 2o） was observed together with a reduction in molar extinction coefficient （e） in comparison with both meta-alkylated azobenzenes （4m and 5m） and 7p lacking the meta and ortho substituents. For orthoalkylated azobenzene, photochemical trans-to-cis isomerization and thermal back cis-to-trans isomerization in solution oc- curred slowly when compared with 4m, 5m and 7p. The half-life time of the cis form of 20 was found to be 380 h, which is about 8-50 times longer than those of comparable 4m, 5m （43-13 h） and 7p （7 h）. Furthermore, comparison of the molecular structure and isomerization characteristics of azobenzene thiol （20 and 5m） self-assembled monolayers on flat gold surfaces indicates that the trans-to-cis photoconversion in monolayer systems is influenced by steric hindrance and strong intermoleculax interaction between azobenzene units.

关键词： azobenzene isomerization lifetime of cis form molecular structure

Dynamics of an ensemble of clumps embedded in a magnetized ADAF

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2015年第12期15卷 2187-2192页

作者： Fazeleh Khajenabi mina Rahmani Department of Physics Golestan University Department of Physics Damghan University

We investigate the effects of a global magnetic field on the dynamics of an ensemble of clumps within a magnetized advection-dominated accretion flow by ignoring interactions between the clumps and then solving the collisionless Boltzman equation. In the strong-coupling limit, in which the averaged radial and rotational velocities of the clumps follow dynamics described by an Advection-Dominated Accretion Flow （ADAF）, the root mean square radial velocity of the clumps is cal- culated analytically for different magnetic field configurations. The value of the root mean square radial velocity of the clumps increases by increasing the strength of the radial or vertical components of the magnetic field, but a purely toroidal magnetic field geometry leads to a reduction in the value of the root mean square radial velocity of the clumps in the inner parts by increasing the strength of this component. Moreover, dynamics of the clumps strongly depend on the amount of advected energy so that the value of the root mean square radial velocity of the clumps increases in the presence of a global magnetic field as the flow becomes more advective.

关键词： accretion -- accretion disk -- black hole physics -- magnetohydrody- namics

L^p-decay rates to nonlinear diffusion waves for p-system with nonlinear damping

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2006年第6期49卷 721-739页

作者： ZHU Changjiang JIANG mina Laboratory of Nonlinear Analysis Department of Mathematics Central China Normal University Wuhan 430079 China Laboratory of Nonlinear Analysis Department of Mathematics Central China Normal University Wuhan 430079 China

In this paper, we study the Lp (2≤p≤ +∞) convergence rates of the solutions to the Cauchy problem of the so-called p-system with nonlinear damping. Precisely, we show that the corresponding Cauchy problem admits a unique global solution (v (x,t), u(x, t)) and such a solution tends time-asymptotically to the corresponding nonlinear diffusion wave ((v|-)(x,t),(u|-)(x,t)) governed by the classical Darcy's law provided that the corresponding prescribed initial error function lies in and is sufficiently small. Furthermore, the Lp (2≤p≤ +∞) convergence rates of the solutions are also obtained.

关键词： nonlinear damping, nonlinear diffusion waves, convergence rates, energy estimates.

Testing development of different surface treatments on pervious concrete

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2016年第4期10卷 385-393页

作者： mina YEKKALAR Liv HASELBACH Quinn LANGFITT Civil and Environmental Engineering Washington State University Pullman WA 99164-2910 USA

Pervious concrete systems are developing stormwater management technologies which also have wintertime benefits as melting snow may percolate into the system instead of refreezing on the surface. Enhancing the surface microtexture of pervious concrete may also be beneficial in preventing icing or slipping by pedestrians. This research explored different surface treatments on pervious concrete specimens both qualitatively from personal judgements, and quantitatively through static friction measurements with a spring balance with respect to ＂slipperiness＂. The tests were performed on both dry and wet specimens. One aim was to determine whether the spring balance method may be a simple test for comparing surface treatments on pavement samples with little surface area such as laboratory specimens or sidewalk sections. The other purpose was to make a preliminary decision of which surface treatments to use for a sidewalk installation for future studies on wintertime performance. The reliability analysis of the spring balance results showed that there was high operator consistency. In addition, there was a high level of consistency on average results between the quantitative and qualitative methods. This implies that the spring balance test may be an acceptable methodology for comparative analyses with respect to static friction.

关键词： pervious concrete static coefficient of friction pedestrian