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Numerical modeling of gas-phase kinetics in formation of secondary aerosol

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China Particuology 2007年第4期5卷 267-273页

作者： wang-kun Chen Ping wang Department of Property and Environmental Management Jinwen University of Science & Technology Taipei Taiwan China Department of Civil Engineering Ching-Yun University Chungli Taiwan China

Three basic modules of gas-phase photochemical reactions involved in the formation of secondary aerosol are developed for modeling the concentration variation of precursors of aerosol, including ketone （RCOx）, aldehyde （ALD）, peroxyacetylnitrate （PAN）, NO2, and SO2, followed by numerical solution for each of the modules. Reasonable trends of concentration variation of the precursors can be obtained from the proposed modules.

关键词： Aerosol Photochemical reaction Numerical modeling

Semisolid forging electronic packaging shell with silicon carbon-reinforced copper composites

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Rare Metals 2013年第2期32卷 191-195页

作者： Kai-kun wang School of Materials Science and Engineering University of Science and Technology Beijing

To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed： temperature 1,025 ℃and holding time 5 min.

关键词： Semi-solid forming Silicon carbon reinforcedcopper composites Electronic packaging shell Microstructure

Thixo-forging and simulation of complex parts of aluminum alloy AlSi7Mg

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International Journal of Minerals,Metallurgy and Materials 2010年第1期17卷 53-57页

作者： Kai-kun wang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

In order to investigate the formability of metal material in semisolid state, a series of experiments were carried out by thixo-forging the complex part of aluminum alloy AlSi7Mg. Through changing the upper punch, aluminum parts with different upper-cup dimensions can be successfully produced. The numerical simulation was conducted for investigating the forming limits of AlSi7Mg during thixo-forging. It is found that the simulation result is in good agreement with the experiment one.

关键词： thixo forging aluminum alloy formability numerical simulation

Modified molecular matrix model for predicting molecular composition of naphtha＇

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Chinese Journal of Chemical Engineering 2017年第12期25卷 1856-1862页

作者： kun wang Shiyu Li School of Chemical Engineering and Technology Tianjin University Tianjin 300354 China

To improve the naphtha composition prediction model based on molecular type homologous series matrix （MTHS）, this paper puts forward a novel molecular matrix to characterize the naphtha composition and the norreal distribution hypothesis to better describe the molecular composition distribution within each homologous series of the molecular matrix. Through prediction calculation of eight groups of naphtha samples and eight groups of gasoline samples, it is verified that the normal distribution hypothesis is more applicable than gamma distribution hypothesis for the prediction model. According to the prediction results of the samples, the restrain range of normal distribution parameters during model computing process is summarized. With the bulk properties of naphtha samples and the value range of distribution parameters as input conditions, this study utilizes the improved novel molecular matrix to predict the composition of naphtha samples. As the results show, the novel molecular matrix can predict more detailed composition information of naphtha and improve prediction accuracy with less unknown parameters.

关键词： MTHS molecular matrix Distribution assumption Naphtha Molecular composition Prediction model

Area-preserving mean curvature flow of rotationally symmetric hypersurfaces with free boundaries

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Science China Mathematics 2016年第3期59卷 493-502页

作者： wang kun Bo Department of Mathematics Zhejiang University

We consider the area-preserving mean curvature flow with free Neumann boundaries. We show that a rotationally symmetric n-dimensional hypersurface in R^(n+1)between two parallel hyperplanes will converge to a cylinder with the same area under this flow. We use the geometric properties and the maximal principle to obtain gradient and curvature estimates, leading to long-time existence of the flow and convergence to a constant mean curvature surface.

关键词： area-preserving mean curvature flow symmetric hypersurfaces free boundary

Effect of crystalline grain structures on the mechanical properties of twinning-induced plasticity steel

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Acta Mechanica Sinica 2016年第1期32卷 181-187页

作者： kun wang Dan wang Fusheng Han Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences

In order to improve the mechanical properties of twinning-induced plasticity steel, the grain morphology was tailored by different solidification technologies combined with deformation and heat treatment processing routes. Three typical grain morphologies, i.e., equiaxed, columnar as well as equiaxed/columnar grains were formed, and their mechan- ical behaviors were comparatively studied. Among the three materials, the equiaxed grain material exhibited the highest strength but the lowest plasticity. Depending on the grain size, the smaller the grain size, the higher the strength, but the lower the elongation. The columnar grain material pos- sessed the most excellent plasticity but the weakest strength. These properties presented a non-monotonic dependence on the dendrite spacing, and the moderate spacing resulted in the optimum combination of strength and plasticity. The equiaxed/columnar grain coexisted material showed inter- esting properties, i.e., the strength and plasticity were just between those of single grain-shaped materials. The three materials also presented different strain hardening behaviors particularly in the uniform deformation stage. The equiaxed grain material showed a constant strain hardening rate, while the columnar grain and equiaxed/columnar grain materials showed a progressively increasing rate with increasing the true strain.

关键词： TWIP steel Twins Crystalline grainstructures Mechanical properties

Necessary and Sufficient Conditions for Expansions of Wilson Type

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Acta Mathematica Sinica,English Series 2008年第7期24卷 1107-1116页

作者： kun Chuan wang Department of Mathematics National Hualien University of Education Hua-Lien Taiwan 970-03

We consider expansions of the type arising from Wilson bases. We characterize such expansions for L^2（R）. As an application, we see that such an expansion must be orthonormal, in contrast to the case of wavelet expa... 详细信息

关键词： Gabor expansion orthogonality wavelet expansion Wilson expansion

Existence of invariant curves for area-preserving mappings under weaker non-degeneracy conditions

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Frontiers of Mathematics in China 2020年第3期15卷 571-591页

作者： kun wang Junxiang XU School of Mathematics Southeast UniversityNanjing 211189China

We consider a class of analytic area-preserving mappings Cm-smoothly depending on a *** imposing on any non-degeneracy assumption,we prove a formal KAM theorem for the mappings,which implies many previous KAM-type results under some non-degeneracy ***,by this formal KAM theorem,we can also obtain some new interesting results under some weaker non-degeneracy ***,the formal KAM theorem can be regarded as a general KAM theorem for areapreserving mappings.

关键词： Area-preserving mapping invariant curve KAM iteration nondegeneracy condition

Twin delayed deep deterministic policy gradient-based intelligent computation offloading for IoT

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Digital Communications and Networks 2023年第4期9卷 836-845页

作者： Siguang Chen Bei Tang kun wang School of Internet of Things Nanjing University of Posts and TelecommunicationsNanjing210003China Jiangsu Engineering Research Center of Communications and Network Technology Nanjing University of Posts and TelecommunicationsNanjing210003China Department of Electrical and Computer Engineering University of CaliforniaLos AngelesCA90095USA

In view of the randomness distribution of multiple users in the dynamic large-scale Internet of Things(IoT)scenario,comprehensively formulating available resources for fog nodes in the area and achieving computation services at low cost have become great *** a result,this paper studies an efficient and intelligent computation offloading mechanism with resource ***,an optimization problem is formulated to minimize the total energy consumption of all tasks under the joint optimization of computation offloading decisions,bandwidth resources and transmission ***,a Twin Delayed Deep Deterministic Policy Gradient-based Intelligent Computation Offloading(TD3PG-ICO)algorithm is proposed to solve this optimization *** combining the concept of the actor critic algorithm,the proposed algorithm designs two independent critic networks that can avoid the subjective prediction of a single critic network and better guide the policy network to generate the global optimal computation offloading ***,this algorithm introduces a continuous variable discretization operation to select the target offloading node with random *** available resources of the target node are dynamically allocated to improve the model decision-making ***,the simulation results show that this proposed algorithm has faster convergence speed and good *** can always approach the greedy algorithm with respect to the lowest total energy ***,compared with full local and Deep Q-learning Network(DQN)-based computation offloading schemes,the total energy consumption can be reduced by an average of 15.53%and 6.41%,respectively.

关键词： Fog computing Computation offloading Deep reinforcement learning Resource allocation