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Approximations to Isentropic Planar Magneto-Hydrodynamics Equations by Relaxed Euler-Type Systems

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Chinese Annals of Mathematics,Series B 2024年第3期45卷 413-440页

作者： Yachun LI Zhaoyang SHANG Chenmu WANG Liang ZHAO School of Mathematical Sciences CMA-ShanghaiMOE-LSC and SHL-MACShanghai Jiao Tong UniversityShanghai 200240China School of finance Shanghai Lixin University of Accounting and FinanceShanghai 201209China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China School of Mathematical Sciences Harbin Engineering UniversityHarbin 150001China Mathematical Modelling&Data Analytics Center Oxford Suzhou Centre for Advanced ResearchSuzhou 215123JiangsuChina

In this paper, the authors consider an approximation to the isentropic planar Magneto-hydrodynamics(MHD for short) equations by a kind of relaxed Euler-type system. The approximation is based on the generalization of the Maxwell law for nonNewtonian fluids together with the Maxwell correction for the Ampe`re law, hence the approximate system becomes a first-order quasilinear symmetrizable hyperbolic systems with partial dissipation. They establish the global-in-time smooth solutions to the approximate Euler-type equations in a small neighbourhood of constant equilibrium states and obtain the global-in-time convergence towards the isentropic planar MHD equations. In addition, they also establish the global-in-time error estimates of the limit based on stream function techniques and energy estimates for error variables.

关键词： Planar MHD equations Relaxation limits Global convergence Stream function

SHA: QoS-Aware Software and Hardware Auto-Tuning for Database Systems

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Journal of Computer Science & Technology 2024年第2期39卷 369-383页

作者：李进陈全唐晓新过敏意 Department of Computer Science Shanghai Jiao Tong UniversityShanghai 200240China Department of Computer Science and Technology Shanghai University of Finance and EconomicsShanghai 200433China

While databases are widely-used in commercial user-facing services that have stringent quality-of-service(QoS)requirement,it is crucial to ensure their good performance and minimize the hardware usage at the same *** investigation shows that the optimal DBMS(database management system)software configuration varies for different user request patterns(i.e.,workloads)and hardware *** is challenging to identify the optimal software and hardware configurations for a database workload,because DBMSs have hundreds of tunable knobs,the effect of tuning a knob depends on other knobs,and the dependency relationship changes under different hardware *** this paper,we propose SHA,a software and hardware auto-tuning system for *** is comprised of a scaling-based performance predictor,a reinforcement learning(RL)based software tuner,and a QoS-aware resource *** performance predictor predicts its optimal performance with different hardware configurations and identifies the minimum amount of resources for satisfying its performance *** software tuner fine-tunes the DBMS software knobs to optimize the performance of the *** resource reallocator assigns the saved resources to other applications to improve resource utilization without incurring QoS violation of the database *** results show that SHA improves the performance of database workloads by 9.9%on average compared with a state-of-the-art solution when the hardware configuration is fixed,and improves 43.2%of resource utilization while ensuring the QoS.

关键词： auto-tuning database configuration joint tuning utilization quality-of-service(QoS)

Markovian Quadratic BSDEs with an Unbounded Sub-quadratic Growth

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Chinese Annals of Mathematics,Series B 2024年第3期45卷 441-462页

作者： Jingnan JU Shanjian TANG shanghai Center for Mathematical Sciences Fudan UniversityShanghai 200433China Department of finance and Control Sciences School of Mathematical SciencesFudan UniversityShanghai 200433China

This paper is devoted to the solvability of Markovian quadratic backward stochastic differential equations(BSDEs for short)with bounded terminal *** generator is allowed to have an unbounded sub-quadratic growth in the second unknown variable *** existence and uniqueness results are given to these *** an application,an existence result is given to a system of coupled forward-backward stochastic differential equations with measurable coefficients.

关键词： Markovian BSDE Quadratic growth Unbounded sub-quadratic term coeficients Coupled FBSDE

Private information and investment-q sensitivity:Evidence from new products

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China Journal of accounting Research 2024年第1期17卷 28-44页

作者： Ganbing Li Kai Zhu shanghai university of finance and Economics China

This study shows that a decline in investment efficiency due to information asymmetry may not necessarily devalue a firm but may enhance its value *** base their investment decisions on both public and private ***,effectively transmitting private information to investors in a competitive market is quite challenging,as it leads to stock prices inadequately reflecting a firm’s true ***,firms must invest to achieve their business objectives,which results in a deviation between a firm’s actual investment level and the market’s expected investment level,thereby reducing investment-q ***,this deviation does not imply a waste of societal resources;instead,it improves a firm’s core competitiveness in the product *** consider the future launch of new products as a proxy for firm private *** find that(1)private information is negatively associated with investment-q sensitivity,and that the greater the sales of the new product,the lower the investment-q sensitivity;(2)the negative effect is more pronounced for firms with higher revenue volatility and ownership concentration than for those with lower revenue volatility and ownership *** study helps us to further understand how to evaluate firm investment efficiency from the perspective of private information and provides empirical evidence of the costs of the new product launch process.

关键词： Private information New product Investment-q sensitivity

Quality disclosure strategies for small business enterprises under consumer loss aversion

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Journal of Management Science and Engineering 2024年第1期9卷 62-87页

作者： Danli Yao Simai He Meng Zheng Business School University of Shanghai for Science and TechnologyShanghai200093China School of Information Management and Engineering Shanghai University of Finance and EconomicsShanghai200433China

In this paper,we focus on small business enterprises(SBEs)that usually have low market power but can rely on retailers to transact sales and gain the ability to disclose quality ***,consumer loss aversion(CLA)is pronounced when buying from SBEs that have yet to develop a strong reputation and uncertain *** focus on two competing SBEs with heterogeneous quality levels and discuss their quality disclosure strategiesd whether selling through a retailerd in the context of *** study the interaction between consumers'prior belief in product quality and CLA and how these factors affect equilibrium *** show that a situation in which low-quality and high-quality SBEs both choose to disclose will not occur under a neutral consumer attitude,i.e.,it happens only when the aversion level is *** the aversion level is low,either the low-quality SBE or the high-quality SBE will decide to disclose,and the disclosing party depends on the prior *** addition,CLA significantly impacts the monotonicity of both SBEs'and retailers'prices and profits relating to the consumers'prior beliefs.

关键词： Quality disclosure Consumer loss aversion Competition Game theory

Principal Model Analysis Based on Bagging PLS and PCA and Its Application in Financial Statement Fraud

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Journal of Systems Science and Information 2024年第2期12卷 212-228页

作者： Xiao LIANG Qiwei XIE Chunyan LUO Liang TANG Yi SUN School of Economics and Management Beijing University of TechnologyBeijing 100124China shanghai Tongtu Semiconductor Technology Co. LtdShanghai 210203China School of finance Anhui University of Finance&EconomicsBengbu 233000China

Motivated by the Bagging Partial Least Squares(Bagging PLS)and Principal Component Analysis(PCA)algorithms,a novel approach known as Principal Model Analysis(PMA)method is introduced in this *** the proposed PMA algorithm,the PCA and the Bagging PLS are *** this method,multiple PLS models are trained on sub-training sets,derived from the training set using the random sampling with replacement *** regression coefficients of all the sub-PLS models are fused in a joint regression coefficient *** final projection direction is then estimated by performing the PCA on the joint regression coefficient ***,the proposed PMA method is compared with other traditional dimension reduction methods,such as PLS,Bagging PLS,Linear discriminant analysis(LDA)and *** results on six public datasets demonstrate that our proposed method consistently outperforms other approaches in terms of classification performance and exhibits greater ***,it is employed in the application of financial statement fraud *** and other five algorithms are utilized to financial statement fraud which concerned by the academic community,and the results indicate that the classification of PMA surpassed that of the other methods.

关键词： principal model analysis partial least squares principal component analysis dimension reduction ensemble learning financial statement fraud detection

Foreign Ownership and International Trade Performance in China

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China & World Economy 2024年第2期32卷 42-72页

作者： Zhiyuan Li Yichun Lin Mingyao Xu School of Economics Fudan University shanghai Institute of International finance and Economics China School of Economics Fudan UniversityChina

We investigate the causal relationship between foreign ownership and international trade performance by comparing foreign-acquired firms with similar domestic-acquired firms in China with regard to changes in their post-acquisition international trade *** findings indicate that foreign ownership significantly enhanced the probability of both exporting and importing,and strongly increased trade *** ownership took effect from the year of the acquisition and persisted for at least 2 *** stimulated both processing trade and ordinary trade,and expanded products and trading ***-acquisition trade performance also exhibited heterogeneity based on the different pre-acquisition and post-acquisition *** for the underlying mechanisms,we show that firms experienced significant output expansion,increased export dependence,and eased financial constraints after foreign acquisition.

关键词： domestic acquisition foreign acquisition foreign ownership international trade performance

THE LIMITING PROFILE OF SOLUTIONS FOR SEMILINEAR ELLIPTIC SYSTEMS WITH A SHRINKING SELF-FOCUSING CORE

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Acta Mathematica Scientia 2024年第2期44卷 583-608页

作者：金可石影谢华飞 Zhejiang College Shanghai University of Finance and EconomicsJinhua321013China School of Mathematical Sciences Zhejiang Normal UniversityJinhua321004China School of Mathematics and Statistics Nanyang Normal UniversityNanyang473061China

In this paper,we consider the semilinear elliptic equation systems{△u+u=αQ_(n)(x)|u|^(α-2)|v|^(β)u in R^(N),-△v+v=βQ(x)|u|^(α)|v|^(β-2)v in R^(N),where N≥3,α,β>1,α+β0} shrink to a set with finitely many points as n→∞.Motivated by the work of Fang and Wang[13],we use variational methods to study the limiting profile of ground state solutions which are concentrated at one point of the set with finitely many points,and we build the localized concentrated bound state solutions for the above equation systems.

关键词： Schrödinger system ground states solutions bound state solutions

THE TRUNCATED EM METHOD FOR JUMP-DIFFUSION SDDES WITH SUPER-LINEARLY GROWING DIFFUSION AND JUMP COEFFICIENTS

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Journal of Computational Mathematics 2024年第1期42卷 178-216页

作者： Shounian Deng Chen Fei Weiyin Fei Xuerong Mao Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment Ministry of Educationand School of Mathematics-Physics and FinanceAnhui Polytechnic UniversityWuhu 241000China Business School University of Shanghai for Science and TechnologyShanghai 200093China Department of Mathematics and Statistics University of StrathclydeGlasgow G11XHUK

This work is concerned with the convergence and stability of the truncated EulerMaruyama(EM)method for super-linear stochastic differential delay equations(SDDEs)with time-variable delay and Poisson *** constructing appropriate truncated functions to control the super-linear growth of the original coefficients,we present two types of the truncated EM method for such jump-diffusion SDDEs with time-variable delay,which is proposed to be approximated by the value taken at the nearest grid points on the left of the delayed *** first type is proved to have a strong convergence order which is arbitrarily close to 1/2 in mean-square sense,under the Khasminskii-type,global monotonicity with U function and polynomial growth *** second type is convergent in q-th(q<2)moment under the local Lipschitz plus generalized Khasminskii-type *** addition,we show that the partially truncated EM method preserves the mean-square and H∞stabilities of the true ***,we carry out some numerical experiments to support the theoretical results.

关键词： SDDEs Truncated EM method Time-variable delay Poisson jumps