检索结果-南通市图书馆

Arbitrarily rotating polarization direction and manipulating phases in linear and nonlinear ways using programmable metasurface

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第9期13卷 1789-1800页

作者： Wei Liu Si ran Wang jun Yan Dai Lei Zhang Qiao Chen Qiang cheng Tie jun Cui State Key Laboratory of Millimeter Waves Southeast UniversityNanjing 210096China Institute of Electromagnetic Space Southeast UniversityNanjing 210096China Frontiers Science Center for Mobile Information Communication and Security Southeast UniversityNanjing 210096China Electrical Engineering Department Chalmers University of TechnologyGothenburg 41258Sweden

Independent controls of various properties of electromagnetic(EM)waves are crucially required in a wide range of *** metasurface is a promising candidate to provide an advanced platform for manipulating EM ***,we propose an approach that can arbitrarily control the polarization direction and phases of reflected waves in linear and nonlinear ways using a stacked programmable ***,we extend the space-timecoding theory to incorporate the dimension of polarization,which provides an extra degree of freedom for manipulating EM *** proof-of-principle application examples,we consider polarization rotation,phase manipulation,and beam steering at linear and nonlinear *** validation,we design,fabricate,and measure a metasurface *** experimental results show good agreement with theoretical predictions and *** proposed approach has a wide range of applications in various areas,such as imaging,data storage,and wireless communication.

关键词： surface. nonlinear rotating

Efficient Isomerization for Preparing thans-2,2-Dimethyl-3-(2,2-dichloroethenyl) cyclopropanecarbonyl Chloride

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

Chinese Chemical Letters 1999年第2期10卷 101-102页

作者： jun An MA Run Qiu HUANG jun ran cheng Rui Lian SHAO Zai Guo LI(Institute and State Key Laboratory of Elemento-organic Chemistry, Nankai University, Tianjin300071) Inst. State Key Lab. Elemento-O. Nankai University Tianjin 300071 China

Trans-2,2-dimethyl-3-(2,2-dichloroethenyl)cyclopropanecarbonyl chloride, which is animportant intermediate for insecticides, is obtained by isomerization of the cis/trans-mixture with4- (N,N-dimethylamino) pyridine (D... 详细信息

关键词： Permethric acid chloride dimethylaminopyridine conversion

Synthesis of Asymmetric 4H-1, 3, 2-Benzodioxaphosphorin 2-Sulfides from Intramolecular Cyclization Reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1999年第9期10卷 731-732页

作者： jun ran cheng Jia WEN Rut Lian SHAO Huan Yan CAO Run Qiu HUANG(Institute of Elemento-Organic Chemistry, Nankai University. Tianjin 300071) Nankai Univ Inst Elementoorgan Chem Tianjin 300071 Peoples R China

Asymmetric 6-substituted-2-methoxy-4-(2,4-dichlorophenyl)-4H-1,3,2-benzodioxaphosphorin a-sulfides were prepared from intramolecular cyclization. The diastereomers were separated by column chromatography and fractional crystallization. Their structures were characterized on the basis of H-1 NMR, P-31 NMR and x-ray diffraction analysis.

关键词： 4H-1,3,2-benzodioxaphosphorin diastereomer intramolecular cyclization reaction

Effect of micro-Al_(2)O_(3) powders on oxidation and corrosion behaviors of low-carbon MgO-C refractories

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第6期31卷 1522-1534页

作者： Yang Chen Zeng-yi Li Hao-bo Tan Yu-ran Fu jun Ding cheng-ji Deng Chao Yu School of Materials Science and Engineering Hunan Institute of TechnologyHengyang 421002HunanChina The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

To solve the problem of poor high-temperature service performance caused by low carbonization of MgO-C refractories,low-carbon MgO–C refractories with excellent thermal shock,oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al_(2)O_(3) powders as *** results indicated that the addition of micro-Al_(2)O_(3) powders optimized the internal structure of the material,like the columnar β-Si_(3)N_(4) with a stepped distribution and the mosaic structure formed between granular and flaky Mg_(2)SiO_(4),which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock ***,the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa,***,the addition of micro-Al_(2)O_(3) powders promoted the formation of fine particles of Mg_(2)SiO_(4),MgAl_(2)O_(4) and MgO,as well as a dense protective layer of Mg_(2)SiO_(4) in the material under high-temperature ***,spinel and high-temperature solid solution were formed in the corrosion *** oxidation and corrosion resistances were greatly improved by 41%and 15%,respectively.

关键词： Low-carbon MgO-C refractory Oxidation resistance Corrosion resistance Thermal shock resistance Micro-Al_(2)O_(3)powder

Approximation Algorithms for Solving the 1-Line Minimum Steiner Tree of Line Segments Problem

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

Journal of the Operations Research Society of China 2024年第3期12卷 729-755页

作者： Jian-Ping Li Su-Ding Liu jun-ran Lichen Peng-Xiang Pan Wen-cheng Wang Department of Mathematics Yunnan UniversityKunming650504YunnanChina School of Mathematics and Physics Beijing University of Chemical TechnologyBeijing650504China

We address the 1-line minimum Steiner tree of line segments(1L-MStT-LS)***,given a set S of n disjoint line segments in R^(2),we are asked to find the location of a line l and a set E_(l) of necessary line segments(i.e.,edges)such that a graph consisting of all line segments in S ∪ E_(l) plus this line l,denoted by T_(l)=(S,l,E_(l)),becomes a Steiner tree,the objective is to minimize total length of edges in E_(l) among all such Steiner ***,we are asked to find a set E_(0) of necessary edges such that a graph consisting of all line segments in S ∪ E_(0),denoted by T_(S)=(S,E_(0)),becomes a Steiner tree,the objective is to minimize total length of edges in E_(0) among all such Steiner trees,we refer to this new problem as the minimum Steiner tree of line segments(MStT-LS)*** addition,when two endpoints of each edge in Eo need to be located on two different line segments in S,respectively,we refer to that problem as the minimum spanning tree of line segments(MST-LS)*** obtain three main results:(1)Using technique of Voronoi diagram of line segments,we design an exact algorithm in time O(n log n)to solve the MST-LS problem;(2)we show that the algorithm designed in(1)is a 1.214-approximation algorithm to solve the MStT-LS problem;(3)using the combination of the algorithm designed in(1)as a subroutine for many times,a technique of finding linear facility location and a key lemma proved by techniques of computational geometry,we present a 1.214-approximation algorithm in time O(n^(3) log n)to solve the 1L-MStT-LS problem.

关键词： 1-Line minimum Steiner tree of line segments Minimum spanning tree of line segments Voronoi diagram of line segments Steiner ratio Approximation algorithms

Synthesis of New Cyclic Phosphate of Arylglyoxylonitrile Oximeand Their Diastereomers

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

Chinese Chemical Letters 1999年第6期10卷 445-446页

作者： Zhi Hua MA Rut Lian SHAO Hong Min MA jun ran cheng Run Qiu HUANG(National Key Laboratory of Elemento -Organic chemistry Nankai University. Tianjin 300071) Nankai Univ Natl Key Lab Elementoorgan Chem Tianjin 30071 Peoples R China

Keeping in view the biological activities of 1,3,2-dioxaphosphorinane-2-one and oxime esters. some compounds possessing these two moieties have been synthesized. The configurational assignment and the ratio of cis/trans diastereomers of target products were performed on basis of H-1 NMR. P-31 NMR and confirmed by X-ray diffraction analysis.

关键词： 1,3,2-dioxaphosphorinane-2-one arylglyoxylonitrile diastereomers

Deflagration and detonation induced by shock wave focusing at different Mach numbers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第2期37卷 249-258页

作者： Zezhong YANG jun cheng Bo ZHANG School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

Shock wave focusing is an effective way to create a hot spot or a high-pressure and hightemperature region at a certain place,showing its unique usage in detonation initiation,which is beneficial for the development of detonation-based *** flame propagation behavior after the autoignition induced by shock wave focusing is crucial to the formation and self-sustaining of the detonation *** this study,wedge reflectors with two different angles(60°and 90°)and a planar reflector are employed,and the Mach number of incident shock waves ranging from 2.0 to 2.8 is utilized to trigger different flame propagation *** pressure transducers and the high-speed schlieren imaging system are both employed to investigate the shock-shock collision and ignition *** results reveal a total of four flame propagation modes:deflagration,DDT(Deflagration-to-Detonation Transition),unsteady detonation,and direct *** detonation wave formed in the DDT and unsteady detonation mode is only approximately 75%-85%of the Chapman-Jouguet(C-J)speed;meanwhile,the directly induced detonation wave speed is close to the C-J *** waves,which are strong evidence for the existence of detonation waves,are discovered in *** usage of wedge reflectors significantly reduces the initial pressure difference ratio needed for direct detonation *** also provide a practical method for differentiating between detonation and deflagration modes,which involves contrasting the speed of the reflected shock wave with the speed of the theoretically nonreactive reflected shock *** findings should serve as a reference for the detonation initiation technique in advanced detonation propulsion engines.

关键词： Deflagration Detonation Hydrogen Ignition Shock wave focusing

Cohomology groups of a new class of Kadison-Singer algebras

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第3期67卷 593-606页

作者： Guangyu An Xing cheng jun Sheng School of Mathematics and Data Science Shaanxi University of Science and TechnologyXi’an 710021China

Let N be a maximal discrete nest on an infinite-dimensional separable Hilbert space H,ξ=∑^(∞)_(n=1)en/2n be a separating vector for the commutant N',E_(ξ)be the projection from H onto the subspace[Cξ]spanned by the vectorξ,and Q be the projection from K=H⊕H⊕H onto the closed subspace{(η,η,η)^(T):η∈H}.Suppose that L is the projection lattice generated by the projections(E_(ξ) 0 0 0 0 0 0 0 0),{(E 0 0 0 0 0 0 0 0):E∈N},(I 0 0 0 I 0 0 0 0) and *** show that L is a Kadison-Singer lattice with the trivial ***,we prove that every n-th bounded cohomology group H~n(AlgL,B(K))with coefficients in B(K)is trivial for n≥1.

关键词： Kadison-Singer algebra Kadison-Singer lattice derivation cohomology group

Effects of the Rainfall-Triggered Lisse Effect on the Stability of Loess Slopes

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第4期35卷 1254-1262页

作者： Zhizhou Yang Donghui cheng jun Xia School of Water and Environment Chang’an UniversityXi’an710054China Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education Chang’an UniversityXi’an710054China Key Laboratory of Eco-Hydrology and Water Security in Arid and Semi-Arid Regions of the Ministry of Water Resources Chang’an UniversityXi’an710054China Key Laboratory of Water Cycle&Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China State Key Laboratory of Water Resources&Hydropower Engineering Sciences Wuhan UniversityWuhan430000China

This paper coupled a water-air two-phase hydrodynamic(WATPH)model with the Iverson’s method to analyze the influence of the Lisse effect on the fast groundwater pressure(P_(w))response and the slope ***,the sensitivities of the driving force and loess soil parameters were *** showed that the WATPH model simulated the height and rise of the depth to the water table reasonably *** depth to water table before rainfall(H0)had a significant impact on the Lisse effect and the slope *** the H_(0) was less than approximately 1 m,the rainfall triggered a significant Lisse effect and decreased the slope factor of safety(F_(s)).When the rainfall intensity(R_(i))was higher than the saturated hydraulic conductivity(K_(s)),the Lisse effect and the F_(s) slightly changed with the increase of the R_(i),and the slope tended to be unstable with continuous *** increasing K_(s),the Lisse effect noticeably increased,and the minimum F_(s) quickly *** analysis of the normalized sensitivity coefficient revealed that H_(0) had a dramatic impact on the Lisse effect and loess slope *** different R_(i) and K_(s) values had prominent influences on the Lisse effect and slight impacts on F_(s).

关键词： Lisse effect landslides safety factor rainfall