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Effect of Intake Air Humidification and EGR on Combustion and Emission Characteristics of Marine Diesel Engine at Advanced Injection Timing

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Journal of Thermal Science 2021年第4期30卷 1174-1186页

作者： WANG ke zhao Changpu CAI Yujie 300072

The trade-off between NO_(x)-soot and ISFC(Indicated Specific Fuel Consumption)brings new challenges for the development and application of innovative techniques that could reduce the NO_(x)-soot emissions of diesel engine simultaneously with the lowest possible fuel *** this study,the two coupling measures,advanced SOI(start of injection)respectively coupled with intake air humidification(IAH)and EGR,were used to achieve lower NO_(x)-soot emissions than the original engine while minimizing the increase in *** studies were conducted on a four-stroke supercharged intercooled marine diesel engine under 75%loads at 1350 r/min by using AVL Fire *** advanced SOI varied from 14.5°CA BTDC to 20°CA BTDC;humidity ratio ranged from 0 to 100%in increments of 20%,and EGR rate ranged from 0 to 25%in increments of 5%.The technical route to achieve Tier III emission standards was also analyzed in this *** result indicates that lower in-cylinder pressure,temperature and NO_(x)emissions,higher ISFC and soot emissions are observed when only IAH or EGR technology is applied,while opposite trends are found when only using advanced *** proper combination of different SOI respectively with humidity ratio and EGR rate can improve the trade-off relationship between NO_(x)and ***,the increase in ISFC is improved by using advanced SOI under high EGR rate or humidity *** with the advanced SOI coupled with EGR,advanced SOI coupled with IAH results in less loss of *** results reveal that both above-mentioned coupling measures can achieve low NO_(x)-soot emissions while ensuring that ISFC does not *** expected,there are nine combinations of advanced SOI coupled EGR that can achieve NO emissions to meet the Tier III standard,while advanced SOI coupled IAH has only one combination to meet this regulation.

关键词： intake air humidification EGR advanced SOI NO_(x)-soot emissions ISFC TierⅢ

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Microstructure and thermal expansion of copper-based amorphous alloys during structural relaxation

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China Foundry 2020年第1期17卷 8-14页

作者： jin-bei zhao Xin-hui Fan Bing Li ke Yang Yi-long Kong zhao Wang College of Materials and Chemical Engineering Xi’an Technological University

(Cu43Zr48Al9)98Y2 amorphous alloy bar was prepared by the arc melting copper mold absorption casting method,and then,the amorphous alloy was annealed at different temperatures for different *** influence of heating rate on thermal expansion and thermal stability was studied by thermomechanical analysis(TMA),and the microstructure evolution of the amorphous alloy during structural relaxation and crystallization was studied by XRD and *** show that the structural evolution behavior of the(Cu43Zr48Al9)98Y2 amorphous alloy can be divided into five different stages(structural relaxation preparation stage,structural relaxation stage,first crystallization stage,second crystallization stage,and grain growth stage).When the heating rate is 20 K/min,the amorphous alloy has the smallest thermal expansion coefficient and the best thermal *** width of the supercooled liquid region is 66.42 *** with different relaxation states were prepared by annealing at the heating rate of 20 K/*** structural evolution of amorphous alloys with different relaxation states is as follows:amorphous→CuZr2+AlCu2Zr7→CuZr2+AlCu2Zr7+CuZr(B2)+CuZr(M)+Cu10Zr7→CuZr2+AlCu2Zr7+CuZr(B2)+CuZr(M).After annealing at 706 K and 726 K(in the supercooled liquid region)for 1.5 h,the amorphous-nanocrystalline composites were *** the annealing temperature is 706 K,the crystallization process of the sample is as follows:amorphous→Cu10Zr7→Cu10Zr7+CuZr,and for the sample at 726 K,it is as follows:amorphous→CuZr2+AlCu2Zr7+Cu10Zr7→Cu10Zr7+CuZr2→CuZr2+CuZr(B2)+Cu10Zr7.

关键词： amorphous-nanocrystalline composite materials structural relaxation microstructure thermal expansion thermal stability

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Investigation on the choice of boundary conditions and shape functions for flexible multi-body system

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Acta Mechanica Sinica 2012年第1期28卷 180-189页

作者： ke-Qi Pan jin-Yang Liu School of Naval Architecture Ocean and Civil EngineeringShanghai Jiaotong University200240 ShanghaiChina

The objective of this investigation is to examine the correctness and efficiency of the choice of boundary conditions when using assumed mode approach to simulate flexible multi-body systems. The displacement field due to deformation is approximated by the Rayleigh-Ritz assumed modes in floating frame of reference （FFR） formulation. The deformations obtained by the absolute nodal coordinate （ANC） formulation which are transformed by two sets of reference coordinates are introduced as a criterion to verify the accuracy of the simulation results by using the FFR formulation. The relationship between the deformations obtained from different boundary conditions is revealed. Nu- merical simulation examples demonstrate that the assumed modes with cantilevered-free, simply-supported and free- free boundary conditions without inclusion of rigid body modes are suitable for simulation of flexible multi-body system with large over all motion, and the same physical deformation can be obtained using those mode functions, differ only by a coordinate transformation. It is also shown that when using mode shapes with statically indeterminate boundary conditions, significant error may occur. Furthermore, the slider crank mechanism with rigid crank is accurate enough for investigating boundary condition problem of flexible multi-body system, which cost significant less simulating time.

关键词： Multi-body systems. Boundary conditions - Assumed mode approach

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Geometric nonlinear dynamic analysis of curved beams using curved beam element

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Acta Mechanica Sinica 2011年第6期27卷 1023-1033页

作者： ke-Qi Pan jin-Yang Liu School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University 200240 Shanghai China

Instead of using the previous straight beam element to approximate the curved beam,in this paper,a curvilinear coordinate is employed to describe the deformations,and a new curved beam element is proposed to model the curved *** on exact nonlinear strain-displacement relation,virtual work principle is used to derive dynamic equations for a rotating curved beam,with the effects of axial extensibility,shear deformation and rotary inertia taken into *** constant matrices are solved numerically utilizing the Gauss quadrature integration *** and Newton-Raphson iteration methods are adopted to solve the differential equations of the rigid-flexible coupling *** present results are compared with those obtained by commercial programs to validate the present finite *** order to further illustrate the convergence and efficiency characteristics of the present modeling and computation formulation,comparison of the results of the present formulation with those of the ADAMS software are ***,the present results obtained from linear formulation are compared with those from nonlinear formulation,and the special dynamic characteristics of the curved beam are concluded by comparison with those of the straight beam.

关键词： Curved beam element. Geometric nonlinear formulation Rigid-flexible coupling

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A general law of human mobility

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Science China(Information Sciences) 2015年第10期58卷 24-37页

作者： LIANG Xiao zhao JiChang XU ke key Laboratory of Technology in Geo-spatial Information Processing and Application System Institute of Electronics Chinese Academy of Sciences School of Economics and Management Beihang University State key Laboratory of Software Development Environment Beihang University

The intrinsic factors that drive human mobility have remained unclear for decades. Our observations from both intra-urban and inter-urban trips demonstrate a general law of human mobility. Specifically, the probability that a trip will occur is inversely proportional to the size of population located inside a circle with radius equal to the travel distance centered at the trip origin. A simple parameterless rank-based model is presented; this model can predict human flows with a convincing fidelity. Moreover, existing models can be implemented as special cases of our model, suggesting that our model is stable at more spatial scales. Our model also creates a fundamental bridge between individual mobility and social relationships.

关键词： human mobility social mobility general law rank-based model flux prediction

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Validation method for simulation models with cross iteration

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Journal of Systems Engineering and Electronics 2019年第3期30卷 555-563页

作者： FANG ke zhao Kaibin ZHOU Yuchen Control and Simulation Center Harbin Institute of Technology

Cross iteration often exists in the computational process of the simulation models, especially for control models. There is a credibility defect tracing problem in the validation of models with cross iteration. In order to resolve this problem, after the problem formulation, a validation theorem on the cross iteration is proposed, and the proof of the theorem is given under the cross iteration circumstance. Meanwhile, applying the proposed theorem, the credibility calculation algorithm is provided, and the solvent of the defect tracing is explained. Further, based on the validation theorem on the cross iteration, a validation method for simulation models with the cross iteration is proposed, which is illustrated by a flowchart step by step. Finally, a validation example of a sixdegree of freedom (DOF) flight vehicle model is provided, and the validation process is performed by using the validation method. The result analysis shows that the method is effective to obtain the credibility of the model and accomplish the defect tracing of the validation.

关键词： validation method simulation model cross iteration validation theorem validation example

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Optimizing Emergency Logistics for the Offsite Hazardous Waste Management

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Journal of Systems Science and Systems Engineering 2019年第6期28卷 747-765页

作者： Jiahong zhao Ginger Y.ke School of Civil and Transportation Engineering Guangdong University of TechnologyGuangzhou 510006China Faculty of Business Administration Memorial University of NewfoundlandSt.John'sNewfoundland and LabradorCanada A1B 3X5

Hazardous wastes pose increasing threats to people and environment during the processes of offsite collection,storage,treatment,and disposal.A novel game theoretic model,including two levels,is developed for the corresponding optimization of emergency logistics,where the upper level indicates the location and capacity problem for the regulator,and the lower level reflects the allocation problem for the emergency *** from other works in the literature,we focus on the issue of multi-quality coverages (full and partial coverages) in the optimization of facility location and *** be specific,the regulator decides the location plan and the corresponding capacity of storing emergency groups for multiple types of hazmats,so to minimizes the total potential environmental risk posed by incident sites;while the commander minimizes the total costs to provide an efficient allocation *** solve the bi-level programming model,two solution techniques,namely a KKT condition approach and a heuristic model,are designed and *** proposed model and solution techniques are then applied to a hypothetical case and a real-world case to demonstrate the practicality and provide managerial insights.

关键词： Bi-level programming hazardous material time-based risk assessment multi-quality covering model KKT heuristic technique

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New family of Dirac and Weyl semimetals in XAuTe(X=Na, K,Rb) ternary honeycomb compounds

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Science China(Physics,Mechanics & Astronomy) 2016年第10期59卷 66-71页

作者： Hao Sun jin zhao International Center for Quantum Design of Functional Materials/Hefei National Laboratory for Physical Sciences at Microscale and key Laboratory of Strongly-Coupled Quantum Matter Physics Chinese Academy of Sciences and Department of Physics University of Science and Technology of China Synergetic Innovation Center of Quantum Information & Quantum Physics University of Science and Technology of China Department of Physics and Astronomy University of Pittsburgh

We propose a new family of 3D Dirac semimetals based on XAuTe(X = K, Na, Rb) ternary honeycomb compounds, determined based on first-principles calculations, which are shown to be topological Dirac semimetals in which the Dirac points are induced by band inversion. Dirac points with four-fold degeneracy that are protected by C3 rotation symmetry and located on the Γ-A high-symmetry path are found. Through spatial-inversion symmetry breaking, a K(Au0.5 Hg0.5)(Te0.5As0.5) superlattice structure composed of KHgAs and KAuTe compounds is proven to be a Weyl semimetal with type-II Weyl points, which connect electronand hole-like bands. In this superlattice structure, the six pairs of Weyl nodes are distributed along the K-Γ high-symmetry path on the kz = 0 plane. Our research expands the family of topological Dirac and type-II Weyl semimetals.

关键词： Dirac semimetal type-II Weyl semimetal band inversion

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Review of photoinduced effect in manganite films and their heterostructures

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Chinese Physics B 2018年第11期27卷 215-225页

作者： Xin-Yu Li Long zhao Xiang-Yang Wei Hao Li ke-Xin jin Shaanxi key Laboratory of Condensed Matter Structures and Properties Northwestern Polytechnical University Xi＇an 710072 China

Light–matter interaction plays an important role in the non-equilibrium physics, especially in strongly correlated electron systems with complex phases. Photoinduced effect can cause the variation in the physical properties and produce some emergent phases. As a classical archetype, manganites have received much attention due to their colossal magnetoresistance（CMR） effect and the strong interaction of charge, spin, orbital, and lattice degrees of freedom. In this paper, we give an overview of photoinduced effect in manganites and their heterostructures. In particular, some materials, including ZnO, Si,BiFeO3（BFO）, titanate-based oxides, and 0.7 Pb（Mg（1/3） Nb（2/3））O3-0.3 PbTiO3（PMN-PT） have been integrated with manganites. Heterostructures composed of these materials display some exciting and intriguing properties. We do hope that this review offers a guiding idea and more meaningful physical phenomena will be discovered in active areas of solid state physics and materials science.

关键词： manganites heterostructures photoinduced effect

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Achieving Twin Strengthening in Bulk Aluminum via Adding Nanoparticles Combined with Tailoring Hot Pressing Temperature

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Acta Metallurgica Sinica(English Letters) 2024年第12期37卷 2083-2093页

作者： ke zhao Zhongying Duan jinling Liu Linan An School of Mechanics and Aerospace Engineering Southwest Jiaotong UniversityChengdu610031China Applied Mechanics and Structure Safety key Laboratory of Sichuan Province Southwest Jiaotong UniversityChengdu610031China School of Mechanical Engineering Dongguan University of TechnologyDongguan523808China

It is extremely difficult to strengthen bulk aluminum(Al)by twins,due to its high stacking fault energy under standard loading *** this study,a simple yet effective solution was proposed for introducing twins to strengthen bulk *** method involves the addition of nanoparticles with high volume fraction combined with the tailoring of sintering temperature toward the melting point of Al during hot *** temperature plays an important role in forming twins in bulk Al containing high content *** twin content increases with increasing sintering temperature in the range of 590-640℃.At sintering temperature of 640℃,the twin content reaches 17%,enabling the significant improvement in the yield strength of the bulk Al from 251 to 400 MPa,compared with the sample with few or no *** twin strengthening may serve as a major strengthening mechanism for bulk Al,and its strengthening contribution is comparable to the dominant Orowan strengthening resulting from the added nanoparticles.

关键词： Bulk Al Twins Nanoparticle Sintering temperature Strength Strengthening mechanism

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