检索结果-南通市图书馆

Defence Technology（防务技术） 2023年第10期28卷 330-342页

作者： hao-nan zhao Hong-yuan Fang Xiao-hua zhao Yellow River Laboratory Zhengzhou UniversityZhengzhou450001China

Non aqueous reactive polymer materials produced by the reaction of isocyanate and polyol have been widely used in infrastructure construction,which may be subjected to explosion loads during complex service *** blast response of composite materials is a crucial aspect for applications in engineering structures potentially subjected to extreme *** this work,damage caused to rebar reinforced polymer slabs by surface explosive charges was studied experimentally and numerically.A total of 6 field tests were carried out to investigate the performances of the failure modes of rebar reinforced polymer slabs under contact and near-field *** influence of explosive quantity(10-40 g)and stand-off distances(0-20 cm)at the damage modes were *** results show that the failure modes of rebar reinforced polymer slabs under near-field explosion mainly were bending and surface spalling,while under the impact of contact explosion,the failure modes were craters of the top surface,spalling of the bottom surface,and middle ***,a detailed fully coupled model was developed and validated with the test *** influences of explosive quantity and slab thickness on rebar reinforced polymer slabs under contact explosion were *** on this,the calculation formula between breach diameter,explosive quantity,and slab thickness is fitted.

关键词： Reinforced polymer slab Numerical investigations Empirical prediction Damage models

A Nontrivial Homotopy Element of Order p2 Detected by the Classical Adams Spectral Sequence

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2018年第1期39卷 1-8页

作者： hao zhao Linan ZHONG School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China Department of Mathematics Yanbian UniversityYanji 133002JilinChina

Let p be an odd *** authors detect a nontrivial element p of order p^2 in the stable homotopy groups of spheres by the classical Adams spectral *** is represented by a_0^(p-2)h_1 ∈ Ext_A^(p-1,pq+p-2)(Z/p,Z/p) in th... 详细信息

关键词： Stable homotopy groups of sphere Adams spectral sequence May spectral sequence Massey product

The Asymptotic Distributions of the Largest Entries of Sample Correlation Matrices under an α-mixing Assumption

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2022年第11期38卷 2039-2056页

作者： hao Zhu zhao Yong ZHANG School of Mathematics Jilin UniversityChangchun 130012P.R.China

Let{Xk,i;k≥1,i≥1}be an array of random variables,{Xk;k≥1}be a strictly stationaryα-mixing sequence,where Xk=(Xk,1,Xk,2,...).Let{pn;n≥1}be a sequence of positive integers such that c1≤p n n≤c2,where c1,c2>*** th... 详细信息

关键词： Sample correlation matrices α-mixing sequence Chen-Stein method

Group of Self-Equivalences of Sum Object

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2007年第12期23卷 2145-2154页

作者： hao zhao Wen Huai SHEN School of Mathematical Sciences Nankai University Tianjin 300071 P. R. China School of Mathematical Sciences South China Normal University Guangzhou 510631 P. R. China

In general category, the group of self-equivalences of sum object can decompose as the product of its two subgroups under certain conditions and also several split short exact sequences are obtained. Subsequently, we apply the above results to the category of space under a space and get some results which are dual to those in fibrewise category.

关键词： group of self-equivalences fibrewise category category of space under a space

P-symmetric Subharmonic Solutions for Nonlinear Hamiltonian Systems

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第6期40卷 1388-1408页

作者： Duan Zhi ZHANG Zhi hao zhao School of Mathematical Sciences Nankai UniversityTianjin 300071P.R.China

In this paper,we prove that for each positive k≡1 mod m there exists a P-symmetric kmτ-periodic solution xk for asymptotically linear mτ-periodic Hamiltonian systems,which are nonautonomous and endowed with a *** the P-symmetric Hamiltonian function is semi-positive,one can prove,under a new iteration inequality of the Maslov-type P-index,that xk_(1) and xk_(2) are geometrically distinct for k_(1)/k_(2)≥(2n+1)m+1;and xk_(1),xk_(2) are geometrically distinct for k_(1)/k_(2)≥m+1 provided xk_(1) is non-degenerate.

关键词： P-symmetric subharmonic Hamiltonian systems Maslov-type index theory iteration inequality asymptotically linear

Effects of Halogen Substitution on Naphthazarin Tautomerism in the Ground and Excited States

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2007年第8期26卷 980-987页

作者： zhao Xue CHEN De-Zhan WANG Zhen hao zhao-Ling Department of Chemistry Taishan University Taian 271000 China College of Chemistry Shandong Normal University Jinan 250014 China

5,8-Hihydroxyl-1,4-naphthazarin was taken as a model compound to explore the effect of halogen substitution on intramolecular proton transfer process. Calculations indicate that the substitution in the R2- and R4-positions far away from the active region has much weaker influence on the IPT process than that in the R1- and R3-positions. IPT barriers for substitution in the R1-position are higher than that of parent molecule. However, it is quite reverse for substitution in the R3-position. The IPT process is a proton transfer process coupled with charge separation and coulombic interaction would be dominant during this process. As for naphthazarin, halogen substitution would decrease the quantum yields of O2 but increase those of ^1O2.

关键词： naphthazarin intramolecular proton transfer halogen substitution

Four Families of Nontrivial Product Elements in the Stable Homotopy Groups of Spheres

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2022年第3期43卷 459-472页

作者： Linan ZHONG Jianguo HONG hao zhao Department of Mathematics Yanbian UniversityYanji 133002JilinChina Sino-European Institute of Aviation Engineering Civil Aviation University of ChinaTianjin 300300China School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China

In this paper,the authors introduce a new effective method to compute the generators of the E-term of the May spectral *** helps them to obtain four families of non-trivial product elements in the stable homotopy grou... 详细信息

关键词： Stable homotopy groups of spheres Adams spectral sequence May spectral sequence

Effect of La_(2)Sn_(2)O_(7)content on Ag-La_(2)Sn_(2)O_(7)/SnO_(2)arc erosion behavior and mechanism

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第9期40卷 1488-1498,I0006页

作者： Mengli Cao Yi Feng Lili Wang Ting zhao hao zhao Zijue Zhou School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China

La_(2)Sn_(2)O_(7)/SnO_(2)powder was synthesized by chemical co-precipitation method,and Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites were prepared by hot-pressing *** electrical resistivity,density,Brinell hardness and flexural strength of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites were ***,the effect of La_(2)Sn_(2)O_(7)content on the arc erosion behavior of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites at 7 kV voltage was *** the increase of La_(2)Sn_(2)O_(7)content,the arc duration and arc energy decrease,and the breakdown strength *** surface morphology of Ag-La_(2)Sn_(2)O_(2)/SnO_(2)composites after arc erosion was investigated using scanning electron microscopy and three-dimensio nal laser confocal scanning *** the increase of La_(2)Sn_(2)O_(7)content,the smaller the erosion damage,the better the anti-arc erosion ***,too much La_(2)Sn_(2)O_(7)results in the decrease of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)properties and severe arc erosion.X-ray photoelectron spectroscopy was used to determine the composition of the erosion *** effect of La_(2)Sn_(2)O_(7)on wettability between Ag and SnO_(2)was investigated,and the erosion mechanism of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites was discussed *** study can provide a reference for the application of Ag matrix electrical contact materials in high-voltage electrical appliances.

关键词： Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites Arc erosion behavior Erosion mechanism Rare earths

Gas Pool Coupled Activating TIG Welding Method with Coupling Arc Electrode

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2018年第6期31卷 169-176页

作者： Yong Huang Rui-Lin Liu Yan-zhao hao State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of Technology Lanzhou 730050 China Department of Aviation Manufacture Engineering Chengdu Aeronautic Polytechnic Chengdu 610100 China Technology Center Great Wall Motor Company Limited Baoding 071000 China

Gas pool coupled activating TIG(GPCA?TIG) welding put forward in?house can dramatically enhance weld penetration of TIG welding through introducing active element oxygen to reverse the Marangoni convection flow in the molten pool. In order to further improve the welding productivity, the normal solid tungsten electrode is replaced by a kind of coupling arc electrode. The changes of arc pressure distribution along anode surface and the weld appearance were evaluated. On this basis, the dependences of weld shape characterized with weld depth, width and undercut on the main welding parameters were discussed. The results indicate, the substitution of coupling arc electrode can lead to an obvious decrease of arc pressure. Compared to hollow tungsten electrode and twin tungsten electrodes, the coupling arc electrode is much easier to manufacture and has more compacter structure. Combined with the symmetric distribution of arc pressure in di erent directions, this electrode has extensive adaptability. In the GPCA?TIG welding with coupling arc electrode, both the substitution of coupling arc electrode and the introduction of outer active gas oxygen can reduce the possibilities of producing humping bead and undercut. Their joint action makes this welding method have the capability of realizing high travel speed and deep penetration welding.

关键词： GPCA?TIG welding Coupling arc electrode Oxygen Arc pressure Weld shape Welding parameter

Digital Cofibration and Digital Lusternik-Schnirelmann Category in the Sense of Subdivision

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2023年第1期44卷 35-48页

作者： Hongjie ZHANG Linan ZHONG hao zhao School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China Department of Mathematics Yanbian UniversityYanji 133002JilinChina

In this paper, using the notion of subdivision, the authors generalize the definition of cofibration in digital topology and show that this kind of cofibration is injective in the sense of subdivision. Meanwhile, they give the necessary condition under which a digital map is a cofibration. Furthermore, they consider the Lusternik-Schnirelmann category of digital maps in the sense of subdivision and give several fundamental homotopy properties about it.

关键词： Digital topology Digital cofibration Lusternik-Schnirelmann category