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A practical path guiding method for participating media

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Computational Visual Media 2020年第1期6卷 37-51页

作者： Hong Deng beibei wang Rui wang Nicolas Holzschuch Nanjing University of Science and Technology Nanjing 210094China State Key Lab of CAD&CG Zhejiang UniversityHangzhou 310058China Univ.Grenoble-Alpes InriaCNRSGrenoble INPLJK38000 GrenobleFrance

Rendering translucent materials is costly:light transport algorithms need to simulate a large number of scattering events inside the material before reaching *** cost is especially high for materials with a large albedo or a small mean-freepath,where higher-order scattering effects *** simple terms,the paths get lost in the *** guiding has been proposed for surface rendering to make convergence faster by guiding the sampling *** this paper,we introduce a path guiding solution for translucent *** learn an adaptive approximate representation of the radiance distribution in the volume and use it to sample the scattering direction,combining it with phase function sampling by resampled importance *** proposed method significantly improves the performance of light transport simulation in participating media,especially for small lights and media with refractive *** method can handle any homogeneous participating medium,with high or low scattering,with high or low absorption,and from isotropic to highly anisotropic.

关键词： Monte Carlo ray tracing path guiding volume light transport participating media rendering

A survey on rendering homogeneous participating media

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Computational Visual Media 2022年第2期8卷 177-198页

作者： Wenshi Wu beibei wang Ling-Qi Yan School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjingChina University of California Santa BarbaraUSA

Participating media are frequent in real-world scenes,whether they contain milk,fruit juice,oil,or muddy water in a river or the *** light interacts with these participating media in complex ways:refraction at boundaries and scattering and absorption inside *** radiative transfer equation is the key to solving this *** are several categories of rendering methods which are all based on this equation,but using different *** this paper,we introduce these groups,which include volume density estimation based approaches,virtual point/ray/beam lights,point based approaches,Monte Carlo based approaches,acceleration techniques,accurate single scattering methods,neural network based methods,and spatially-correlated participating media related *** well as discussing these methods,we consider the challenges and open problems in this research area.

关键词： participating media Monte Carlo methods rendering volume density estimation

Partially known information attack on SM2 key exchange protocol

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Science China(Information Sciences) 2019年第3期62卷 61-74页

作者： Wei WEI Jiazhe CHEN Dan LI beibei wang China Information Technology Security Evaluation Center Institute for Advanced Study Tsinghua University

SM2 key exchange protocol is a part of the SM2 public key cryptographic algorithm based on elliptic curves which has been issued by Chinese State Cryptography Administration since 2010. Under the guide of Chinese government, SM2 has been widely used in Chinese commercial applications. This paper gives the first partially known information attack on SM2 key exchange protocol. Our attack is based on a technique modified from the hidden number problem(HNP) which was introduced originally to study the bit security of Diffie-Hellman and related schemes. We present a polynomial-time algorithm which could recover the user’s secret key when given about half least significant bits of the two unknown intermediate values in each congruence over about 30 to 40 instances. Compared with the standard HNP, our approach deals with congruence involved two independent unknown variables and each of them possesses the same size as the secret key. Moreover, our results almost coincide with the previous best result among the same field considering the extreme case in which one variant is completely revealed.

关键词： SM2 key exchange protocol cryptanalysis information leakage lattice attack extended hidden number problem

Flux mechanism of compound flux on ash and slag of coal with high ash melting temperature

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1200-1206页

作者： Chengli Wu beibei wang Jiuqiang Zheng Hanxu Li School of Chemical Engineering Anhui University of Science and Technology

The melting temperature of Z coal ash was reduced by adding calcium–magnesium compound flux(WCaO/WMgO=1). In the process of simulated coal gasification, the coal ash and slag were prepared. The transformation of minerals in coal ash and slag upon the change of temperature was studied by using X-ray diffraction(XRD). With the increase of temperatures, forsterite in the ash disappears, while the diffraction peak strength of magnesium spinel increases,and the content of the calcium feldspar increases, then the content of the amorphous phase in the ash increases obviously. The species and evolution process of oxygen, silicon, aluminum, calcium, magnesium at different temperatures were analyzed by X-ray photoelectron spectroscopy(XPS). The decrease of the ash melting point mainly affects the structural changes of silicon, aluminum and oxygen. The coordination of aluminum and oxygen in the aluminum element structure, e.g., tetracoordinated aluminum oxide, was changed. Tetrahedral [AlO4] and hexacoordinated aluminoxy octahedral [AlO6] change with the temperature changing. The addition of Ca2+ and Mg2+ destroys silica chain, making bridge oxide silicon change into non-bridge oxysilicon;and bridge oxygen bond was broken and non-bridge oxygen bond was produced in the oxygen element structure. The addition of calcium and magnesium compound flux reacts with aluminum oxide tetrahedron, aluminum oxide octahedron and silicon tetrahedron to promote the breakage of the bridge oxygen bond. Ca2+ and Mg2+ are easily combined with silicon oxide and aluminum oxide tetrahedron and aluminum. Oxygen octahedrons combine with non-oxygen bonds to generate low-melting temperature feldspars and magnesite minerals, thereby reducing the coal ash melting temperatures. The structure of kaolinite and mullite was simulated by quantum chemistry calculation, and kaolinite molecule has a stable structure.

关键词： Coal ash and slag Compound flux X-ray photoelectron spectroscopy Transformation of mineral structure Structure of kaolinite and mullite

Effect of Direct Aging on Corrosion Behavior of AlSi10Mg Alloy Fabricated by Laser Powder Bed Fusion

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 266-282页

作者： Zhen Zhang Zhanyong Zhao Xiaofeng Li beibei wang Peikang Bai Shanxi Key Laboratory of Controlled Metal Solidification and Precision Manufacturing School of Materials Science and EngineeringNorth University of ChinaTaiyuan030051China Technical Center Taiyuan Iron and Steel(Group)Co.LtdTaiyuan030003China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China

Effect of direct aging of 170℃on corrosion behavior of laser powder bed fused AlSi10Mg(LPBF-AlSi10Mg)was studied by microstructure analysis,electrochemical analysis and X-ray photoelectron *** results show that direct aging of 170℃has little effect on melt pool and Si cellular structure,but promotes the precipitation of nano-Si particles and releases the residual *** increasing aging time from 0 to 4 h to 24 h,the corrosion property of the LPBF-AlSi10Mg is deteriorated,which is evidenced by increased corrosion current density and decreased pitting potential and polarization *** increasing the aging time,the thickness of the oxide film formed on surface of the LPBF-AlSi10Mg *** Si content of the oxide film of the sample aging for 4 h is the lowest,9.42 at.%,and it is the highest,18.62 at.%,for the sample aging for 24 *** electrochemical noise analysis reveals that the middle-frequency contribution of the Hilbert spectrum is responsible for the deteriorated corrosion performance,which corresponds to metastable pitting initiated by nano-Si particles.

关键词： Laser powder bed fusion AlSi10Mg Direct aging Corrosion

Real-time all-frequency global llumination with radiance caching

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Computational Visual Media 2024年第5期10卷 923-936页

作者： Youxin Xing Gaole Pan Xiang Chen Ji Wu Lu wang beibei wang School of Software Shandong UniversityJinan 250101China School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China

Global illumination(GI)plays a crucial role in rendering realistic results for virtual exhibitions,such as virtual car *** scenarios usually include all-frequency bidirectional reflectance distribution functions(BRDFs),although their geometries and light configurations may be *** allfrequency BRDFs in real time remains challenging due to the complex light *** approaches,including precomputed radiance transfer,light probes,and the most recent path-tracing-based approaches(ReSTIR PT),cannot satisfy both quality and performance requirements ***,we propose a practical hybrid global illumination approach that combines ray tracing and cached GI by caching the incoming radiance with *** approach can produce results close to those of ofline renderers at the cost of only approximately 17 ms at runtime and is robust over all-frequency *** approach is designed for applications involving static lighting and geometries,such as virtual exhibitions.

关键词： real-time global illumination all-frequency BRDFs Haar wavelets radiance caching

Research on the Effects of the Most Used Market Power Mitigation Mechanisms Considering Different Market Environments

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Energy Engineering 2022年第6期119卷 2193-2210页

作者： Yangsheng Sun Zhihuawang Gaoqinwang beibei wang State Grid Shanghai Municipal Electric Power Company Shanghai200122China China Electric Power Research Institute Co. Ltd.Nanjing210003China Southeast University Nanjing210096China

The market power mitigation method of the supply-side has become one of the key points affecting the stability of the electricity spot *** mitigation mechanisms are used in the current mature electricity markets of the ***,the same market power mitigation mechanism shows different effects in different market *** market operator in the world needs the most efficient way to mitigate market *** that there is no relevant literature discussing the market power effects of different mitigation methods in detail,the mitigation effects need to be discussed and further ***,we analyze the effects of the most utilized market power mitigation mechanisms while considering different market ***,we establish a Nash-Stackelberg interactive game model to simulate the competitive strategies of power ***,the different market power mitigation approaches are ***,a multi-agent system(MAS)genetic interior-point algorithm is proposed to solve the problem of ***,through the simulation analysis,the market power mitigation effects of different mechanisms while considering three operation states of the system in two market structures are all analyzed.

关键词： Supply-side market power mitigation mechanism market operating state bilevel interactive game model effect analysis

Classification of protein domains based on their three-dimensional shapes (CPD3DS)

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Synthetic and Systems Biotechnology 2021年第3期6卷 224-230页

作者： Zhaochang Yang Mingkang Liu Bin wang beibei wang School of Life Science and Technology University of Electronic Science and Technology of ChinaChina School of Information and Software Engineering University of Electronic Science and Technology of ChinaChina Centre for Informational Biology University of Electronic Science and Technology of China2006 Xiyuan RoadChengduSichuan611731China

Protein design has become a powerful method to expand the number of natural proteins and design customized proteins according to ***-based protein design spares the need to create novel elements from scratch,which makes it a more efficient strategy than scratch-based protein design in designing multi-domain proteins,protein complexes and *** the surface shape plays a central role in domain-domain and protein-protein interactions,a global map of the surface shapes of all domains should be very beneficial for domain-based protein ***,in this study,we characterized the surface shapes of protein domains,collected from CATH and SCOP databases,with their 3D-Zernike descriptors(3DZDs).Then similarities of domain shape features were identified,and all domains were classified *** preferences of the combinations of domains between different clusters were analyzed in natural proteins from the Protein Data Bank.A user-friendly website,termed CPD3DS,was also developed for storage,retrieval,analyses and visualization of our *** work not only provides an overall view of protein domain shapes by showing their variety and similarities,but also opens up a new avenue to understand the properties of protein structural domains,and design principles of protein architectures.

关键词： 3D-zernike descriptors K-means Shape similarity Domain surface shapes Structural similarity

Health risk assessment of dietary exposure to polycyclic aromatic hydrocarbons in Taiyuan, China

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Journal of Environmental Sciences 2014年第2期26卷 432-439页

作者： Jing Nie Jing Shi Xiaoli Duan beibei wang Nan Huang Xiuge Zhao Chinese Research Academy of Environmental Sciences State Key Lab of Environmental Criteria and Risk Assessment Soil and Water Science College of Resources and Environmental Sciences China Agricultural University Department of Safety Engineering China Institute of Industrial Relations

Sixteen polycyclic aromatic hydrocarbons （PAHs） were determined in 24 duplicate-diet samples from people in Taiyuan during summer and winter in 2009. Dietary intake of PAHs for 2862 participants was subsequently estimated by a survey in Taiyuan. Results from these 24 samples were compared with a raw food study in Taiyuan in 2008. Three main sources of dietary PAHs are vegetables, wheat flour and fruits, the sum of which contributes 75.95% of PAHs in dietary food. Compared to the estimated value in raw food, much more B[a]Peq （benzo[a]pyrene equivalents） were detected in food samples collected in the duplicate-diet study in Taiyuan （60.75 ng/day）. The cooking process may introduce more B[a]Peq into food, and the relative contribution of 16 PAHs in the diet would be changed during the cooking procedure.

关键词： dietary exposure food health risk assessment polycyclic aromatic hydrocarbons (PAHs) benzo[a]pyrene