检索结果-南通市图书馆

Free vibration and buckling analysis of polymeric composite beams reinforced by functionally graded bamboo fbers

Applied mathematics and mechanics(English Edition) 2024年第3期45卷 543-562页

作者： H.m.FEIZABAD m.H.YAS Department of mechanical Engineering Razi UniversityKermanshah ***Iran

natural fibers have been extensively researched as reinforcement materials in polymers on account of their environmental and economic advantages in comparison with synthetic fibers in the recent *** fibers are renowned for their good mechanical properties,abundance,and short cycle *** beams are one of the fundamental structural components and are susceptible to mechanical loads in engineering applications,this paper performs a study on the free vibration and buckling responses of bamboo fiber reinforced composite(BFRC)beams on the elastic *** different functionally graded(FG)layouts and a uniform one are the considered distributions for unidirectional long bamboo fibers across the *** elastic properties of the composite are determined with the law of *** Hamilton’s principle,the governing equations of motion are *** generalized differential quadrature method(GDQm)is then applied to the equations to obtain the *** achieved outcomes exhibit that the natural frequency and buckling load values vary as the fiber volume fractions and distributions,elastic foundation stiffness values,and boundary conditions(BCs)and slenderness ratio of the beam ***,a comparative study is conducted between the derived analysis outcomes for BFRC and homogenous polymer beams to examine the effectiveness of bamboo fibers as reinforcement materials,demonstrating the significant enhancements in both vibration and buckling responses,with the exception of natural frequencies for cantilever beams on the Pasternak foundation with the FG-◇fiber ***,the obtained analysis results of BFRC beams are also compared with those for carbon nanotube reinforced composite(CNTRC)beams found in the literature,indicating that the buckling loads and natural frequencies of BFRC beams are lower than those of CNTRC beams.

关键词： bamboo fiber free vibration buckling analysis functionally graded(FG)beam elastic foundation generalized differential quadrature method(GDQm)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhanced quantum resources via two distant atom-cavity systems under the influence of atomic dissipation

引用

Communications in Theoretical Physics 2024年第2期76卷 62-73页

作者： m Setodeh Kheirabady m K Tavassoly m Rafeie E Ghasemian Laser and Optics Group Faculty of PhysicsYazd UniversityYazd 89195-741Iran Department of Electrical Engineering Faculty of Intelligent Systems Engineering and Data SciencePersian Gulf UniversityBushehrIran

Quantum resources such as entanglement and coherence are the holy grail for modern quantum technologies. Although the unwanted environmental effects tackle quantum information processing tasks, suprisingly these key quantum resources may be protected and even enhanced by the implementation of some special hybrid open quantum systems. Here, we aim to show how a dissipative atom-cavity-system can be accomplished to generate enhanced quantum *** do so, we consider a couple of dissipative cavities, where each one contains two effective two-level atoms interacting with a single-mode cavity field. In practical applications, a classical laser field may be applied to drive each atomic subsystem. After driving the system, a Bell-state measurement is performed on the output of the system to quantify the entanglement and coherence. The obtained results reveal that the remote entanglement and coherence between the atoms existing inside the two distant cavities are not only enhanced, but can be stabilized, even under the action of dissipation. In contrast, the local entanglement between two atoms inside each dissipative cavity attenuates due to the presence of unwanted environmental ***, the local coherence may show the same behavior as the remote ***, the system provides the steady state entanglement in various interaction regimes,particularly in the strong atom-cavity coupling and with relatively large detuning. more interestingly, our numerical analyses demonstrate that the system may show a memory effect due to the fact that the death and revival of the entanglement take place during the interaction. Our proposed model may find potential applications for the implementation of long distance quantum networks. In particular, it facilitates the distribution of quantum resources between the nodes of large-scale quantum networks for secure communication.

关键词： remote entanglement and coherence atomic dissipation steady state entanglement Bell-statemeasurement

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

地铁区间运行列车火灾早期烟气特性研究

引用

铁道工程学报 2024年第8期41卷 111-115页

作者：江崇旭那艳玲中国铁路设计集团有限公司天津300142

研究目的:探明区间运行列车火灾早期烟气特性是火灾快速精准探测、定位、预警的基础。本文通过建立运行列车火灾数值仿真计算模型,计算120 km/h区间运行列车车顶、车底、车头、车中、车尾6个工况火灾早期不同时刻空气温度、烟气浓度的... 详细信息

研究目的:探明区间运行列车火灾早期烟气特性是火灾快速精准探测、定位、预警的基础。本文通过建立运行列车火灾数值仿真计算模型,计算120 km/h区间运行列车车顶、车底、车头、车中、车尾6个工况火灾早期不同时刻空气温度、烟气浓度的变化规律。研究结论:(1)地铁区间运行列车火灾烟气呈非对称分布,烟气主要向车尾传播蔓延,火点前方1 m处已检测不到明显温度、烟气浓度变化;(2)测点温度和烟气浓度实时监测值与火源间距呈负相关规律,距火点相同距离处车底火灾空气温度较车顶火灾高100%,烟气浓度高500%;(3)相对速度差对绝对温度比影响较小,在5 m/s和10 m/s速度差下,距火点1 m处绝对温度比均大于0.45,在距火点3 m处绝对温度比均大于0.75;(4)本研究成果可为地铁防火标准完善和防排烟设计提供参考。

关键词：地铁区间运动列车火灾早期烟气特性

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of multiple shapes for steady flow with transformer oil+Fe_(3)O_(4)+TiO_(2) between two stretchable rotating disks

引用

Applied mathematics and mechanics(English Edition) 2024年第2期45卷 373-388页

作者： m.RAHmAN m.TURKYILmAZOGLU Z.mUSHTAQ Department of mathematics Mirpur University of Science and TechnologyMirpur 10250Pakistan Department of mathematics Hacettepe UniversityBeytepeAnkara 06532Turkiye

In this study,we examine the effects of various shapes of nanoparticles in a steady flow of hybrid nanofluids between two stretchable rotating *** steady flow of hybrid nanofluids with transformer oil as the base fluid and Fe_(3)O_(4)+TiO_(2)as the hybrid nanofluid is *** shapes of Fe_(3)O_(4)+TiO_(2)hybrid nanofluids,including sphere,brick,blade,cylinder,and platelet,are *** shape exists in the same volume of a *** leading equations(partial differential equations(PDEs))are transformed to the nonlinear ordinary differential equations(ODEs)with the help of similarity *** system of equations takes the form of ODEs depending on the boundary conditions,whose solutions are computed numerically by the bvp4c mATLAB *** outputs are compared with the previous findings,and an intriguing pattern is discovered,such that the tangential velocity is increased for the rotation parameter,while it is decreased by the stretching values because of the lower *** the reaction rate parameter,the concentration boundary layer becomes shorter,and the activation energy component increases the rate at which mass transfers come to the higher disk but have the opposite effect on the bottom *** ranges of various parameters taken into account are Pr=6.2,Re=2,m=1.0,φ_(1)=φ_(2)=0.03,K=0.5,S=-0.1,Br=0.3,Sc=2.0,α_(1)=0.2,γ=0.1,E_(n)=2.0,and q=1.0,and the rotation factor K is within the range of 0 to 1.

关键词： transformer oil Brinkman number skin friction coefficient double rotating disk Nusselt number Sherwood number

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhancement of coercivity,permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites for memory and high frequency devices

引用

Journal of Rare Earths 2024年第6期42卷 1128-1135,I0005页

作者： I.Sardar m.D.Hossain m.S.Sikder m.N.I.Khan m.R.Rahman Physics Discipline Khulna UniversityKhulna9208Bangladesh Department of Physics Khulna University of Engineering&TechnologyKhulna9203Bangladesh Department ofComputer Science and Engineering Northern University of Business&Technology KhulnaKhulna9100Bangladesh material Science Division Atomic Energy CentreDhaka1000Bangladesh

Spinel cubic ferrites have huge applications in me mory and high frequency *** the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important *** article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and *** X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEm),energy dispersive X-ray(EDX),vibrating sample magnetometer(VSm),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the *** XRD patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped *** densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu *** FTIR analysis also proves the spinel cubic phase of the *** average grain size of the ferrites is obtained via FESEm images,and it is increased from 121 to 198 *** analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ***,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EDX study shows that there is no impurity contamination in the *** permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric *** dependent resistivity and impedance analysis also show the improved *** the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.

关键词： Ferrites Raree arths Coercivity Permeability EDX Resistivity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

布达拉宫地震危险性分析

引用

振动与冲击 2024年第15期43卷 95-104页

作者：崔玥杨娜北京交通大学土木建筑工程学院北京100044

布达拉宫是我国著名的世界文化遗产,其所在地区活动断层发育、大地震频发。开展可靠的地震危险性评估,可为该研究区内以布达拉宫为首的藏式古建筑抗震保护提供依据。该文对比传统地震危险性分析方法的不足,采用基于多锁固段破裂理论的... 详细信息

布达拉宫是我国著名的世界文化遗产,其所在地区活动断层发育、大地震频发。开展可靠的地震危险性评估,可为该研究区内以布达拉宫为首的藏式古建筑抗震保护提供依据。该文对比传统地震危险性分析方法的不足,采用基于多锁固段破裂理论的地震物理预测方法,提出了地震危险性评估的系统流程。并根据地震烈度和地震动参数衰减关系,考虑场地自身条件,进行了布达拉宫所在区域的地震危险性评估。研究结果表明,该研究区位于林芝地震区,未来100年内该研究区的地震危险性主要为林芝地震区的下一次m_(S)8.5主震或m_(S)7.8标志性地震;发震断层位于亚东-谷露断层中段附近的纳木错东南岸断裂,震中位置为30.3°N,90.1°E附近;布达拉宫建筑群坐落在基岩,不考虑山体场地放大作用,结构接地端地震作用与基岩相当。研究结论为开展布达拉宫建筑群结构抗震研究提供理论依据。

关键词：布达拉宫锁固段衰减关系标志性地震场地条件

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dipeptidyl peptidase-4 inhibitors and the risk of infection: A systematic review and meta-analysis of cardiovascular outcome trials

引用

World Journal of Diabetes 2024年第5期15卷 1011-1020页

作者： na Yang Li-Yun He Peng Liu Zi-Yi Li Yu-Cheng Yang Fan Ping Ling-Ling Xu Wei Li Hua-Bing Zhang Yu-Xiu Li Department of Endocrinology Key Laboratory of Endocrinology of National Health CommissionPeking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100730China Department of Endocrinology The First Affiliated Hospitaland College of Clinical Medicine of Henan University of Science and TechnologyLuoyang 471000Henan ProvinceChina

BACKGROUND Since adverse events during treatment affect adherence and subsequent glycemic control,understanding the safety profile of oral anti-diabetic drugs is imperative for type 2 diabetes mellitus(T2Dm)*** To evaluate the risk of infection in patients with T2Dm treated with dipeptidyl-peptidase 4(DPP-4)*** Electronic databases were *** selection criteria included randomized controlled trials focused on cardiovascular *** these studies,the effects of DPP-4 inhibitors were directly compared to those of either other active anti-diabetic treatments or *** trials involving 53616 patients were deemed *** calculated aggregate relative risks employing both random-effects and fixed-effects approaches,contingent upon the *** The application of DPP-4 inhibitors showed no significant link to the overall infection risk[0.98(0.95,1.02)]or the risk of serious infections[0.96(0.85,1.08)],additionally,no significant associations were found with opportunistic infections[0.69(0.46,1.04)],site-specific infections[respiratory infection 0.99(0.96,1.03),urinary tract infections 1.02(0.95,1.10),abdominal and gastrointestinal infections 1.02(0.83,1.25),skin structure and soft tissue infections 0.81(0.60,1.09),bone infections 0.96(0.68,1.36),and bloodstream infections 0.97(0.80,1.18)].CONCLUSION This meta-analysis of data from cardiovascular outcome trials revealed no heightened infection risk in patients undergoing DPP-4 inhibitor therapy compared to control cohorts.

关键词： T2Dm drugs treatment

来源：

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

旗鼓相当还是相形失色?——境内并购与跨境并购的生产效率比较研究

引用

管理评论 2024年第8期36卷 65-78页

作者：李娜陈奉先山东财经大学金融学院济南250014 首都经济贸易大学金融学院北京100070

提高全要素生产率是实现经济高质量发展的动力源泉。本文通过构建两国古诺双头垄断模型,比较了企业无并购、境内并购和跨境并购时的全要素生产率差异,并以2008—2020年中国上市公司的1229起境内并购和111起跨境并购事件为研究对象,采用... 详细信息

提高全要素生产率是实现经济高质量发展的动力源泉。本文通过构建两国古诺双头垄断模型,比较了企业无并购、境内并购和跨境并购时的全要素生产率差异,并以2008—2020年中国上市公司的1229起境内并购和111起跨境并购事件为研究对象,采用倾向得分匹配和多时点双重差分法实证检验并购行为对企业全要素生产率的影响与作用机制。研究发现:(1)境内并购和跨境并购均显著提升了企业的全要素生产率,且跨境并购的提升作用更为明显。当企业为非国有企业、高新技术企业、受融资约束程度低的企业,且两国政治关系良好、东道国制度质量高时,上述现象表现尤为显著。(2)进一步研究发现,跨境并购通过创新协同效应、管理协同效应对企业全要素生产率的提升作用强于境内并购。不同的是,境内并购的市场垄断效应对全要素生产率起到负面作用,而跨境并购的市场垄断效应并不显著。三种效应叠加最终使得境内并购的全要素生产率提升效应明显弱于跨境并购。在贸易纷争不断的背景下,鼓励我国企业“走出去”整合外部资源,同时积极营造公平竞争的市场环境助力企业整合内部资源,这对实现全要素生产率提升、经济高质量增长具有重要意义。

关键词：境内并购跨境并购全要素生产率 PSm-DID

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Neutron star core-crust transition and the crustal moment of inertia in the nonlinear relativistic Hartree approximation

引用

Chinese Physics C 2024年第3期48卷 133-141页

作者：李牛韦斯纳杨荣瑶叶婧蒋维洲 School of Physics Southeast UniversityNanjing 211189China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

We investigate the effects of theσmeson mass(m_(σ)),symmetry energy,and slope of the symmetry energy on the neutron star core-crust transition density and the crustal moment of inertia(ΔI/I)in the nonlinear relativistic Hartree approach(RHA),which includes vacuum *** the core-crust transition density(ρ_(t)),pressure(P_(t)),and neutron star radius(R),which are all dependent on the symmetry energy,contribute to determiningΔI/I,we find that changing only the slope of symmetry energy within a reasonable range is not sufficient to reachΔI/I≥7%to achieve the large glitches of the Vela ***,since all three factors(ρ_(t),P_(t),and R)increase with the increase in mσthrough scalar vacuum polarization,adjusting mσcan easily achieveΔI/I≥7%.

关键词： symmetry energy relativistic Hartree approximation random phase approximation core-crust transition density pulsar glitch

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Facile synthesis of samarium and cerium doped double perovskite cobaltite with enhanced dielectric response

引用

Journal of Rare Earths 2024年第7期42卷 1317-1327,I0005页

作者： Yasir Abbas m.Kamran m.Anis-ur-Rehman Applied Thermal Physics Laboratory Department of PhysicsCOMSATS University IslamabadIslamabad 45550Pakistan

The investigation of Sm-Ce doping on structure,conduction,and dielectric response of Bi_(2)Ca_(2-2x)Sm_(x)CexCoO_(6)(x=0.000,0.025,0.050,0.075)(BCSCCO)are *** the specimens were synthesized by a facile synthesis technique named the co-precipitation route.X-ray diffraction(XRD)reveals that BCSCCO crystallizes into one phase with space group P21/*** crystallite size,dislocation density,lattice parameters,lattice strain,unit cell volume,and bulk density were determined using XRD *** structural properties of Bi_(2)Ca_(2)CoO_(6)were examined using calculations based on the density functional *** and experimental values discrepancy is less than 1%.A scanning electron microscope was used for performing a microstructural *** SEm images demonstrate the homogeneous distribution of grains with a range of sizes(0.054-0.090μm).The alternating current(ac)conductivity,dielectric permittivity,and tangent loss were also studied as a function of frequency(20 Hz-3 mHz)at different temperatures(100-500℃).All synthesized samples were examined using non-linear Debye's function to determine their spreading factor and relaxation *** specimen with the lowest crystallite size(∼23 nm)exhibits a high dielectric permittivity(∼3.80×10^(6)).The conduction mechanism was examined in the studied samples with the use of Jonscher's power *** power law indicates that the BCSCCO(x=0.000,0.025)follows correlated barrier hopping,whereas the x=0.050 and 0.075 compositions follow non-overlapping polaron *** studied specimen Bi_(2)Ca_(1.9)0Sm_(0.05)0Ce_(0.05)_(0)CoO_(6)with the highest density(∼5.65 g/cm^(3))displays a high electrical conductivity(∼46.1 S/cm).These findings correspond to those published for ceramics made from calcium cobaltite using solid-state reactions(5.0-26.0 S/cm).

关键词： Bismuth calcium samarium cerium cobaltite (BCSCCO) Spreading factor Conduction mechanism Rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：