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Analysis of the heat transfer in unsymmetrically heated triangular microchannels in slip flow regime

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Science China(Technological Sciences) 2004年第4期47卷 436-446页

作者： ZHU Xun LIAO Qiang XIN Mingdao Institute of Engineering Thermophysics Chongqing University Chongqing 400044 China Institute of Engineering Thermophysics Chongqing University Chongqing 400044 China Institute of Engineering Thermophysics Chongqing University Chongqing 400044 China

A theoretical analysis of heat transfer characteristics is presented for the fully developed laminar flow of the incompressible gas in the triangular microchannels heated unsymmetrically with constant axial heat flux. Through solving the energy equation with temperature jump boundary conditions in slip flow regime by virtue of a computation- oriented method of the orthonormal function analysis, the dimensionless temperature profiles and the average Nusselt number for various thermal boundary conditions are obtained. The effects of Knudsen number, aspect ratio, and thermal boundary conditions on the heat transfer are discussed. The calculated results show that the orthonormal function method can be used to study the heat transfer characteristics of the unsymmetrically heated triangular microchannels. The average Nusselt number in triangular microchannels is lower for slip flow than for no-slip flow, and decreases with increasing Knudsen number. The aspect ratios and thermal boundary conditions of triangular microchannels have significant influences on the change of average Nusselt numbers with the increase in the Knudsen number. For the equilateral triangular microchannels, the decrease of the Nusselt number ratio due to temperature jump is smaller at large Knudsen number and larger at small Knudsen number on the boundary condition of bottom wall heated alone as compared with the one on the boundary condition of two heated hypotenuse walls. The correlations of the average Nusselt number with the Knudsen number for equilateral triangular microchannels are obtained.

关键词： slip flow regime, triangular microchannel, unsymmetrical thermal boundary, heat transfer.

Superconvergence for triangular finite elements

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Science China Mathematics 1999年第9期42卷 917-924页

作者：陈传淼 Institute of Computation Hunan Normal University Changsha China

Based on two classes of the orthogonal expansions in a triangle, superconvergence of m-degree triangular finite element solution (for even m) and its average gradient (for odd m) at symmetric points for a second order elliptic problem are studied. There are no other superconvergence points independent of the coefficients of elliptic equation.

关键词： superconvergence triangular element any degree.

Phonon Focusing Effect in an Atomic Level triangular Structure

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Chinese Physics Letters 2023年第9期40卷 61-65页

作者：姜剑辉鲁爽陈杰 Center for Phononics and Thermal Energy Science China–EU Joint Lab for NanophononicsMOE Key Laboratory of Advanced Micro-structured MaterialsSchool of Physics Science and EngineeringTongji UniversityShanghai 200092China

The rise of artificial microstructures has made it possible to modulate propagation of various kinds of waves,such as light,sound and *** them,the focusing effect is a modulation function of particular *** propose an atomic level triangular structure to realize the phonon focusing effect in single-layer *** the positive incident direction,our phonon wave packet simulation results confirm that multiple features related to the phonon focusing effect can be controlled by adjusting the height of the triangular *** interestingly,a completed different focusing pattern and an enhanced energy transmission coefficient are found in the reverse incident *** detailed mode conversion physics is discussed based on the Fourier transform analysis on the spatial distribution of the phonon wave *** study provides physical insights to achieving phonon focusing effect by designing atomic level microstructures.

关键词： structure phonon triangular

A Comparative Investigation on the JT Effect in triangular Compounds of NaMnO_(2), NaNiO_(2) and NaTiO_(2)

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Chinese Physics Letters 2011年第6期28卷 233-236页

作者： OUYANG Sheng-De QUAN Ya-Min LIU Da-Yong ZOU Liang-Jian Key Laboratory of Materials Physics Institute of Solid State PhysicsChinese Academy of SciencesP.O.Box 1129Hefei 230031

We present a study on the Jahn–Teller(JT)distortions of the TiO_(6),NiO_(6)and MnO_(6)complexes in NaTiO_(2),NaNiO_(2)and NaMnO_(2)triangular compounds with a C_(2)/m *** JT vibronic normal modes are found to be Q3,Q'4 and Q6 by the group symmetry on the C2/m *** magnitude of the normal coordinates(Q3,Q'4,Q6)and the structural parameters of distorted octahedra MO_(6)(M=Ti,Ni,Mn)are obtained and in good agreement with experimental *** energy level splitting of 3d orbitals and the highest occupied molecular orbital(HOMO)character in the MO_(6)complex are also calculated in accordance with the JT *** results provide a first insight into the groundstate and magnetic properties of distorted triangular compounds AMO_(2).

关键词： structure distorted triangular

18-DOF triangular Quasi-Conforming Element for Couple Stress Theory

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Computer Modeling in Engineering & Sciences 2016年第6期111卷 473-492页

作者： Xiangkui Zhang ChangshengWang Ping Hu School of Automotive Engineering State Key Laboratory of Structural Analysis for Industrial EquipmentDalian University of TechnologyDalian 116024P.R.China

The basic idea of quasi-conforming method is that the strain-dis-placement equations are weakened as well as the equilibrium *** this paper,an 18-DOF triangular element for couple stress theory is proposed within the framework of quasi-conforming *** formulation starts from truncated Taylor expansion of strains and appropriate interpolation functions are chosen to calculate strain *** element satisfies C0 continuity with second order accuracy and weak C1 continuity *** examples demonstrate that the proposed model can pass the C0??1 patch test and has high *** element does not exhibit extra zero energy modes and can capture the scale effects of microstructure.

关键词： couple stress theory triangular quasi-conforming element enhanced patch test scale effect

Development and Application of a High-Performance triangular Shell Element and an Explicit Algorithm in OpenSees for Strongly Nonlinear Analysis

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Computer Modeling in Engineering & Sciences 2019年第9期120卷 561-582页

作者： Xinzheng Lu Yuan Tian Chujin Sun Shuhao Zhang Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry Department of Civil EngineeringTsinghua UniversityBeijing100084China Beijing Engineering Research Center of Steel and Concrete Composite Structures Tsinghua UniversityBeijing100084China.

The open-source finite element software,OpenSees,is widely used in the earthquake engineering ***,the shell elements and explicit algorithm in OpenSees still require further ***,in this work,a triangular shell element,NLDKGT,and an explicit algorithm are proposed and implemented in ***,based on the generalized conforming theory and the updated Lagrangian formulation,the proposed NLDKGT element is suitable for problems with complicated boundary conditions and strong *** accuracy and reliability of the NLDKGT element are validated through typical ***,by adopting the leapfrog integration method,an explicit algorithm in OpenSees and a modal damping model are ***,the stability and efficiency of the proposed shell element and explicit algorithm are validated through the nonlinear time-history analysis of a highrise building.

关键词： triangular shell element explicit algorithm OpenSees strong nonlinearity

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Applied Mathematics(A Journal of Chinese Universities) 2019年第2期34卷 229-252页

作者： J Dhivya B Sridevi Department of Mathematics Kumaraguru College of TechnologyCoimbatoreTamil NaduIndia Department of Mathematics PSG College of TechnologyCoimbatoreTamil NaduIndia

Similarity measure is an essential tool to compare and determine the degree of similarity between intuitionistic fuzzy sets (IFSs). In this paper, a new similarity measure between intuitionistic fuzzy sets based on the mid points of transformed triangular fuzzy numbers is proposed. The proposed similarity measure provides reasonable results not only for the sets available in the literature but also gives very reasonable results, especially for fuzzy sets as well as for most intuitionistic fuzzy sets. To provide supportive evidence, the proposed similarity measure is tested on certain sets available in literature and is also applied to pattern recognition and medical diagnosis problems. It is observed that the proposed similarity measure provides a very intuitive quantification.

关键词： Fuzzy sets (FSs) Intuitionistic fuzzy sets (IFSs) Most intuitionistic fuzzy sets (MIFSs) Simi- larity measure (SM) Transformed triangular fuzzy numbers (TTFNs)

Local derivation on triangular subalgebras of hyperfinite von Neumann algebras

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Chinese Science Bulletin 1998年第9期43卷 716-719页

作者： JI Peisheng Department of Mathematics, Shandong University, Jinan 250100, China Department of Mathematics Shandong University Jinan China

It is proved that every σ-weakly continuous local derivation from triangular subalgebra A of hyperfinite von Neumann algebra B into A (or B) is a derivation. Morevoer, if A is also a σ-Dirichlet subalgebra, each loc... 详细信息

关键词： hyperfinite von Neumann algebra triangular algebra derivation local derivation inner derivation.

Photonic generation of triangular and rectangular waveforms based on four-wave mixing effect

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Optoelectronics Letters 2022年第1期18卷 6-12页

作者： YUAN Jin WANG Yujie ZHANG Hui ZHANG Mengsi LI Zengrui State Key Laboratory of Media Convergence and Communication Communication University of ChinaBeijing 100044China

A photonic approach that can generate triangular and rectangular waveforms is proposed.A dual-electrode Mach-Zehnder modulator(De-MZM)is used to fulfill the external optical carrier suppression(OCS)modulation of a continuous wave(CW).The follow-up four-wave mixing(FWM)in a semiconductor optical amplifier(SOA)makes four primary sidebands exist in the *** filtering and optical carrier recovery techniques are used to construct the spectrum aligning with that of a triangular/rectangular *** this work,we also elaborate the influence of errors of key device parameters,by which the feasibility and stability of the system have been *** on this photonic approach,a 10 GHz full-duty-cycle triangular waveform and a 50%-duty-cycle rectangular waveform are successfully *** approach provides a feasible method to generate multiple waveforms.

关键词： spectrum. triangular rectangular