检索结果-南通市图书馆

Elastic modulus and thermal stress in coating during heat cycling with different substrate shapes

Frontiers of Mechanical Engineering 2015年第3期10卷 294-300页

作者： Daniel GAONA Alfredo VALAREZO Mechanical Engineering Universidad San Francisco de Quito QuitoEcuador Material Science and Engineering Universidad San Francisco de QuitoQuito Ecuador

The elastic modulus of a deposit （Ed） can be obtained by monitoring the temperature （AT） and curvature （Ak） of a one-side coated long plate, namely, a onedimensional （1D） deformation model. The aim of this research is to design an experimental setup that proves whether a 1D deformation model can be scaled for complex geometries. The setup includes a laser displace- ment sensor mounted on a robotic arm capable of scanning a specimen surface and measuring its deformation. The reproducibility of the results is verified by comparing the present results with Stony Brook University Laboratory＇s results. The Ak-AT slope error is less than 8%, and the Eo estimation error is close to 2%. These values reveal the repeatability of the experiments. Several samples fabri- cated with aluminum as the substrate and 100MXC nanowire （Fe and Cr alloy） as the deposit are analyzed and compared with those in finite element （FE） simula- tions. The linear elastic behavior of 1D （flat long plate） and 2D （squared plate） specimens during heating/cooling cycles is demonstrated by the high linearity of all Ak-AT curves （over 97%）. The Ed values are approximately equal for 1D and 2D analyses, with a median of 96 GPa and standard deviation of 2 GPa. The correspondence between the experimental and simulated results for the 1D and 2D specimens reveals that deformation and thermal stress in coated specimens can be predicted regardless of specimen geometry through FE modeling and by using the experimental value of Ed. An example of a turbine-blade- shaped substrate is presented to validate the approach.

关键词： in-plane Young’s modulus curvature temperature thermal stress coating

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

A lead role for a“secondary”axonal injury response

引用

Neural Regeneration Research 2025年第2期20卷 469-470页

作者： Melissa A.Rudy Trent A.Watkins Division of Neuroimmunology and Glial Biology Department of NeurologyUniversity of California at San FranciscoSan FranciscoCAUSA development Disease Modelsand Therapeutics Graduate ProgramBaylor College of MedicineHoustonTXUSA

Stress signaling following axon injury stimulates a transcriptional program for regeneration that might be exploited to promote central nervous system ***,this stress response drives neuronal apoptosis in non-regenerative *** duality presents a quandary for the development of therapeutic interventions:manipulating stress signaling to enhance recovery of damaged neurons risks accelerating neurodegeneration or restricting regenerative *** dichotomy is well illustrated by the fates of retinal ganglion cells(RGCs)following optic nerve *** this central nervous system injury model,disruption of a stress-activated MAP kinase(MAPK)cascade blocks the extensive apoptosis of RGCs that occurs in wild-type mice(Watkins et al.,2013;Welsbie et al.,2017).

关键词： injury axonal stress

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

Measurements of the Cosmological Parameters Ωmand H0

引用

International Journal of Astronomy and Astrophysics 2018年第4期8卷 386-405页

作者： B. Hoeneisen universidad san francisco de quito Quito Ecuador

From Baryon Acoustic Oscillation measurements with Sloan Digital Sky Survey SDSS DR14 galaxies, and the acoustic horizon angle measured by the Planck Collaboration, we obtain Ωm=0.2724±0.0047, and h+0.020⋅∑mv=0.7038±0.0060, assuming flat space and a cosmological constant. We combine this result with the 2018 Planck “TT, TE, EE + lowE + lensing” analysis, and update a study of ∑mv with new direct measurements of σ8, and obtain ∑mv=0.27±0.08 eV assuming three nearly degenerate neutrino eigenstates. Measurements are consistent with Ωk=0, and Ωde(a)=ΩΛ constant.

关键词： Cosmological Parameters Baryon Acoustic Oscillations Galaxy Distributions Cosmic Microwave Background

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

A Study of Three Galaxy Types, Galaxy Formation, and Warm Dark Matter

引用

International Journal of Astronomy and Astrophysics 2021年第4期11卷 489-508页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

We try to bridge the gap between the theory of linear density-velocity-gravitational perturbations in the early universe, and the relaxed galaxies we observe today. We succeed quantitatively for dark matter if dark matter is warm. The density runs of baryons and of dark matter of relaxed galaxies are well described by hydro-static equations. The evolution from initial linear perturbations to final relaxed galaxies is well described by hydro-dynamical equations. These equations necessarily include dark matter velocity dispersion. If the initial perturbation is large enough, the halo becomes self-gravitating. The adiabatic compression of the dark matter core determines the final core density, and provides a negative stabilizing feedback. The relaxed galaxy halo may form adiabatically if dark matter is warm. The galaxy halo radius continues to increase indefinitely, so has an ill-defined mass.

关键词： Galaxy Formation Warm Dark Matter Adiabatic Invariant of Warm Dark Matter

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

Measurements of the Dark Matter Mass, Temperature and Spin

引用

International Journal of Astronomy and Astrophysics 2024年第3期14卷 184-202页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

We summarize several measurements of the dark matter temperature-to-mass ratio, or equivalently, of the comoving root-mean-square thermal velocity of warm dark matter particles vhrms(1). The most reliable determination of this parameter comes from well measured rotation curves of dwarf galaxies by the LITTLE THINGS collaboration: vhrms(1)=406±69 m/s. Complementary and consistent measurements are obtained from rotation curves of spiral galaxies measured by the SPARC collaboration, density runs of giant elliptical galaxies, galaxy ultra-violet luminosity distributions, galaxy stellar mass distributions, first galaxies, and reionization. Having measured vhrms(1), we then embark on a journey to the past that leads to a consistent set of measured dark matter properties, including mass, temperature and spin.

关键词： Warm Dark Matter Dwarf Galaxies Spiral Galaxies Elliptical Galaxies Galaxy Distributions First Galaxies Reionization

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

The Adiabatic Invariant of Dark Matter in Spiral Galaxies

引用

International Journal of Astronomy and Astrophysics 2019年第4期9卷 355-367页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sample. Fitting the rotation curves, we obtain the root-mean-square (rms) velocity and density of dark matter in the core of the galaxies. We then calculate the rms velocity vhrms (1) that dark matter particles would have if expanded adiabatically from the core of the galaxies to the present mean density of dark matter in the universe. We obtain this “adiabatic invariant” vhrms (1) for 40 spiral galaxies. The distribution of vhrms (1) has a mean 0.87 km/s and a standard deviation of 0.27 km/s. This low relative dispersion is noteworthy given the wide range of the properties of these galaxies. The adiabatic invariant vhrms (1) may, therefore, have a cosmological origin. In this case, the rms velocity of non-relativistic dark matter particles in the early universe when density perturbations are still linear is vhrms (a)=vhrms (1)/a, where a is the expansion parameter. The adiabatic invariant obtains the ratio of dark matter temperature Th (a) to mass mh in the early universe.

关键词： Spiral Galaxies Dark Matter Dark Matter Properties

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

Warm Dark Matter and the Formation of First Galaxies

引用

Journal of Modern Physics 2022年第6期13卷 932-948页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

By numerical integration of hydro-dynamical equations, we study the formation of elliptical and spiral galaxies starting from primordial linear density-velocity-gravitational perturbations. Both dark matter and baryons are included. Warm dark matter perturbations acquire two low mass cut-offs: the free-streaming cut-off due to the power spectrum free-streaming cut-off factor τ2(k), and the velocity dispersion cut-off. The Press-Schechter mass distribution does not include velocity dispersion, and should not be used below the velocity dispersion cut-off mass. From the formation of first galaxies and reionization, we estimate limits on the non-relativistic warm dark matter velocity dispersion at expansion parameter , with .

关键词： Warm Dark Matter First Galaxies First Stars Population III Stars Reioniza-tion

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

A Study of Dark Matter with Spiral Galaxy Rotation Curves. Part II

引用

International Journal of Astronomy and Astrophysics 2019年第2期9卷 133-141页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

In Part II of this study of spiral galaxy rotation curves we apply corrections and estimate all identified systematic uncertainties. We arrive at a detailed, precise, and self-consistent picture of dark matter.

关键词： Dark Matter Spiral Galaxies Disk Galaxies Majorana Neutrinos

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

Simulations and Measurements of Warm Dark Matter Free-Streaming and Mass

引用

International Journal of Astronomy and Astrophysics 2019年第4期9卷 368-392页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

We compare simulated galaxy distributions in the cold ΛCDM and warm ΛWDM dark matter models. The ΛWDM model adds one parameter to the ΛCDM model, namely the cut-off wavenumber kfs of linear density perturbations. The challenge is to measure kfs. This study focuses on “smoothing lengths” π/kfs in the range from 12 Mpc to 1 Mpc. The simulations reveal two distinct galaxy populations at any given redshift z: hierarchical galaxies that form bottom up starting at the transition mas?Mfs, and stripped down galaxies that lose mass to neighboring galaxies during their formation, are near larger galaxies, often have filamentary distributions, and seldom fill voids. We compare simulations with observations, and present four independent measurements of kfs, and the mass mh of dark matter particles, based on the redshift of first galaxies, galaxy mass distributions, and rotation curves of spiral galaxies.

关键词： Dark Matter Mass Warm Dark Matter Free-Streaming Galaxy Mass Distribution Spiral Galaxy Adiabatic Invariant

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

Exploring Inflation Options for Warm Dark Matter Coupled to the Higgs Boson

引用

International Journal of Astronomy and Astrophysics 2023年第3期13卷 217-235页

作者： Bruce Hoeneisen universidad san francisco de quito Quito Ecuador

We extend the Standard Model with a scalar warm dark matter field S with an interaction with the Higgs boson ∅. This warm dark matter scenario is in agreement with cosmological observations if S and ∅ come into thermal and diffusive equilibrium before the temperature drops below the Higgs boson mass mH. We study inflation driven by the fields ∅ or S, and also study preheating and reheating, in order to constrain the parameters of this extension of the Standard Model. It is remarkable that, with the current data, these models pass a closure test with no free parameters.

关键词： Warm Dark Matter Inflation Preheating Reheating

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

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：