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Commuting Dual Toeplitz Operators on the Polydisk

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Acta Mathematica Sinica,English Series 2007年第5期23卷 857-868页

作者： Yu Feng LU shu Xia shang Department of Applied Mathematics Dalian University of Technology Dalian 116024 P. R. China

On the polydisk, the commutativity of dual Toeplitz operators is studied. We obtain characterizations of commuting dual Toeplitz operators, essentially commuting dual Toeplitz operators and essentially semi-commuting ... 详细信息

关键词： dual Toeplitz operators polydisk Bergman space commute maximal ideal space

How is Systemic Risk Amplified by Three Typical Financial Networks

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Journal of the Operations Research Society of China 2022年第3期10卷 579-598页

作者： Jia-Li Ma shu-shang Zhu Xiao-Chuan Pang College of Big Data Statistics Guizhou University of Finance and EconomicsGuiyang550025GuiZhouChina School of Business Sun Yat-Sen UniversityGuangzhou510275GuangdongChina

Financial institutions are typically tied together via inter-liability,portfolio overlapping and share *** connections among financial institutions constitute the three most common financial networks,which may lead to financial risk contagion and even systemic risk when some institutions suffer *** this paper,firstly,for a given shock,we prove the existence of the equilibrium clearing vector of the financial system characterized by these three typical financial ***,we mathematically derive an analytical form to show how these three contagion channels jointly affect and amplify the loss of the non-default institutions,and explain how the lack of liquidity of external investment assets exacerbates the loss caused by portfolio ***,the influence of the characteristics of financial network on risk contagion is verified by numerical *** results provide basis for understanding the financial systemic risk contagion in the real world.

关键词： Systemic risk Inter-liability Share cross-holding Portfolio overlapping Contagion

Preface:Special Issue on New Challenges in Financial Optimization and Risk Management

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Journal of the Operations Research Society of China 2018年第1期6卷 1-2页

作者： Xiao-Guang Yang shu-shang Zhu Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China Department of Finance and Investment Sun Yat-Sen Business SchoolSun Yat-Sen UniversityGuangzhou 510275China

Optimization plays a significant role in both financial theory and ***–variance analysis of portfolio selection,one of the corner stones of modern financial theory,paved by Henry Markowitz in 1952,was modeled exactly as a convex quadratic programming which helps striking a balance between the expected return and investment ***,many financial decision-making problems can be formulated as optimization problems,and accordingly,some most important theories in finance actually originated from the theory of optimization.

关键词： finance return striking

OBSERVATION OF ENERGY DISSIPATION PEAK IN POLYSTYRENE MELT ABOVE T_g

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Chinese Journal of Polymer Science 2007年第6期25卷 629-633页

作者： shu-ying shang Xue-bang Wu Jia-peng shui Zhen-gang Zhu Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences P.O. Box 1129 Hefei 230031 China

In this paper two different kinds of dynamic mechanical techniques （inversed torsion pendulum and energy dissipation apparatus） were used to study the dynamic behavior of atactic monodisperse polystyrene above glass transition. The plots of energy dissipation versus temperature were presented for two atactic polystyrene samples. An apparent energy dissipation peak occurred above Tg in each plot measured by the inversed torsion pendulum, and simultaneously the sample was found to flow assuredly at the moment. To exclude the influence of the flow and demonstrate there was a peak indeed above Tg, the energy dissipation apparatus was used, in which the samples were put into a cup. An obvious peak appeared, and it was in agreement with the peak observed by the inversed torsion pendulum. On basis of the results measured by the two kinds of apparatus, a conclusion is drawn that a peak occurrs above Tg, which gives a manifestation for the existence of the liquid-liquid transition.

关键词： Liquid-liquid transition Polystyrene Energy dissipation apparatus.

Facet Engineering in Constructing Lewis Acid-Base Pairs for CO_(2) Cycloaddition to High Value-Added Carbonates

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Research 2023年第1期2022卷 331-339页

作者： shu shang Wei Shao Xiao Luo Ming Zuo Hui Wang Xiaodong Zhang Yi Xie Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of Energy Hefei Comprehensive National Science CenterHefei 230031China

Cycloaddition of epoxides with CO_(2) to synthesis cyclic carbonates is an atom-economic pathway for CO_(2) utilization with promising industry application value,while its efficiency was greatly inhibited for the lack of highly active catalytic ***,by taking BiOx(X=Cl,Br)with layered structure for example,we proposed a facet engineering strategy to construct Lewis acid-base pairs for CO_(2) cycloaddition,where the typical BiOBr with(O10)facets expose surface Lewis acid Bi sites and Lewis base Br sites *** the combination of in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and theoretical calculations,the oxygen atom of the epoxide is interacted with the Lewis acid Bi site to activate the ternary ring,then facilitates the attack of the carbon atom by the Lewis base Br site for the ring-opening of the epoxide,which is the rate-determining step in the cycloaddition *** a result,the BiOBr-(010)with rich surface Lewis acid-base pairs showed a high conversion of 85%with 100% atomic economy in the synthesis of cyclic-carbonates without any *** study provides a model structure for CO,cycloaddition to high value-added long chain chemicals.

关键词： reaction base synthesis

Incorporating Convexity in Bond Portfolio Immunization Using Multifactor Model:A Semidefinite Programming Approach

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Journal of the Operations Research Society of China 2018年第1期6卷 3-23页

作者： Wei Zhu Cai-Hong Zhang Qian Liu shu-shang Zhu Department of Finance and Investment Sun Yat-Sen Business SchoolSun Yat-Sen UniversityGuangzhou 510275China Ping An Securities Company Ltd Beijing 100033China

Bond portfolio immunization is a classical issue in finance. Since Macaulaygave the concept of duration in 1938, many scholars proposed different kinds of duration immunization models. In the literature of bond portfolio immunization usingmultifactor model, to the best of our knowledge, researchers only use the first-orderimmunization, which is usually called as duration immunization, and no one hasconsidered second-order effects in immunization, which is well known as “convexity” in the case of single-factor model. In this paper, we introduce the second-orderinformation associated with multifactor model into bond portfolio immunization andreformulate the corresponding problems as tractable semidefinite programs. Bothsimulation analysis and empirical study show that the second-order immunization strategies exhibit more accurate approximation to the value change of bonds and thusresult in better immunization performance.

关键词： Immunization Duration Convexity Multifactor model Semidefinite programming

A formally verified transformation to unify multiple nested clocks for a Lustre-like language

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Science China(Information Sciences) 2019年第1期62卷 208-210页

作者： Gang SHI Yucheng ZHANG shu shang Shengyuan WANG Yuan DONG Pen-Chung YEW Department of Computer Science and Technology Tsinghua University Department of Computer Science and Engineering University of Minnesota

Multiple nested clocks is a major language feature in synchronous data-flow languages such as Lustre [1]. To build a formally verified compiler for such a language, it is a common practice to compile the source program to a C-like program first before compiling it to low-level machine-dependent code using a formally verified backend compiler

关键词： A formally verified transformation to unify multiple nested clocks for a Lustre-like language cycle

Single-atom-mediated electron islands boost photocatalytic CO_(2)chemical fixation

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Science China Chemistry 2024年第7期67卷 2292-2299页

作者： shu shang Lei Li Xin He Hui Wang Lirong Zheng Wei Shao Xiaodong Zhang Yi Xie Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of Energy Hefei Comprehensive National Science CenterHefei 230031China Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Chemistry and Chemical Engineering Hefei Normal UniversityHefei 230031China

Photocatalytic cycloadditions of CO_(2)with epoxides are emerging as a significant platform for the green synthesis of valuable carbonates,where efficient catalytic systems with spatially separated charge carriers are ***,a single p-block metal atom is proposed to be a candidate for photogenerated electron localization on a metal oxide *** taking the Bi single-atom supported on ZnO nanosheet(Bi1/ZnO)as an example,we show that the Bi atom plays the role of an electron island in the sea of delocalized holes within ***,the as-formed electron island could readily promote the rate-determining ring-opening process of cycloaddition *** from the unique spatially separated electrons and holes,the Bi1/ZnO achieves a high yield of cyclic carbonates with almost 100%*** study provides a pioneering strategy for enhancing the performances of photocatalytic CO_(2)chemical fixation.

关键词： electron islands CO_(2)photofixation photogenerated charge carriers

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Pre-and post-pollination barriers between two exotic and five native Sagittaria species:Implications for species conservation

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Plant Diversity 2023年第4期45卷 456-468页

作者： Ting-Ting Zou Sen-Tao Lyu Qi-Lin Jiang shu-He shang Xiao-Fan Wang Laboratory of Plant Systematics and Evolutionary Biology College of Life SciencesWuhan UniversityWuhan 430072China

Anthropogenic introduction of species has resulted in a breakdown of geographical barriers and hybridization in previously allopatric ***,examining hybridization proneness of exotic species contributes to revealing its potential ***,reproductive barriers may be strengthened or weakened due to long-term geographical isolation for these newly sympatric ***,few studies have evaluated multiple barriers between alien and native *** this study,we quantified the importance of four pre-pollination barriers(phenological,floral traits,pollen production,and floral constancy)and four post-pollination barriers(pollen-pistil incompatibility,seed set,seed viability,and seedling survival)between two introduced and five native Sagittaria *** showed that introduced *** was cross-compatible with two native species,whereas introduced *** was incapable of hybridizing with any native *** barriers were asymmetric within species pairs and multiple barriers acted in concert to maintain species *** barriers contributed more to total reproductive isolation in native species,whereas prepollination barriers played a stronger role in total reproductive isolation for two introduced *** set was the only barrier that was positively correlated with genetic *** results provide a perspective to better understand reproductive barriers for secondary contact *** highlight the importance of monitoring hybridization events before human introduction and the possible conservation strategies to remove invasive species with hybridization proneness.

关键词： Alismataceae Introduced species Conservation Hybridization Reproductive isolation Sagittaria