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Product of Toeplitz Operators on the Harmonic Dirichlet Space

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Acta Mathematica Sinica,English Series 2012年第5期28卷 1033-1040页

作者： Lian kuo zhao School of Mathematics and Computer Science Shanxi Normal University

In this paper, we study Toeplitz operators with harmonic symbols on the harmonic Dirichlet space, and show that the product of two Toeplitz operators is another Toeplitz operator only if one factor is constant.

关键词： Harmonic Dirichlet space Toeplitz operator zero product

A Class of Normal Weighted Composition Operators on the Fock Space of C^n

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Acta Mathematica Sinica,English Series 2015年第11期31卷 1789-1797页

作者： Lian kuo zhao School of Mathematics and Computer Science Shanxi Normal University

This paper characterizes a class of normal weighted composition operators and their spectrum on the Fock space of Cn.

关键词： Fock space weighted composition operator normal spectrum

A Note on Weighted Composition Operators on the Weighted Bergman Space

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Acta Mathematica Sinica,English Series 2015年第6期31卷 947-952页

作者： Lian kuo zhao Sheng zhao HOU School of Mathematics and Computer Science Shanxi Normal University School of Mathematics Science Soochow University

This paper gives a note on weighted composition operators on the weighted Bergman space, which shows that for a fixed composition symbol, the weighted composition operators are bounded on the weighted Bergman space on... 详细信息

关键词： Weighted Bergman space weighted composition operator boundedness finite Blaschke product

Thermal test and numerical simulation of cooling stave with internal ribbed tube

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Journal of Iron and Steel Research International 2022年第8期29卷 1194-1204页

作者： Xun Xu Li-jun Wu zhao-kuo Yuan Xinglin College Nantong UniversityNantong 226000JiangsuChina School of Mechanical Engineering Tongji UniversityShanghai 201804China

A new type of cooling stave with internal ribbed tube was proposed,and the heat transfer performance of the stave was studied by means of thermal test and numerical *** temperature of cooling stave was monitored in the conditions of furnace gas temperature of 200-700 C and cooling water velocity of 0.2-1.0 m/*** thermal test results show that the internal rib structure can form swirl in the water pipe and improve the cooling capacity of the cooling *** higher the furnace temperature or the lower the cooling water flow rate,the more obvious the advantage of the cooling stave with internal ribbed *** mathematical model of the cooling stave with internal ribbed tube was established by FLUENT software,and the influence of the internal rib structure parameters on the heat transfer performance of the cooling stave was *** is suggested that the parameters of the internal ribbed tube should be 4 ribs,1 mm in height,5-7 mm in width,and 20-30 mm in *** the same common working conditions of the cooling stave,the maximum temperature of the newly designed cooling stave with internal ribbed tube is reduced by 5.6%compared with that of common cooling stave with round *** water flow rate in the internal ribbed tube only needs 0.9 m/s to reach the cooling effect of 2 m/s in the common tube cooling stave,which can save 55%of *** case of water shortage accident of cooling stave,the maximum temperature of the cooling stave with internal ribbed tube is decreased by 22.4%compared with that of common round tube,which can effectively reduce the harm of water shortage and protect the cooling stave.

关键词： Cooling stave Internal ribbed tube Heat transfer Thermal test Numerical simulation

Spectrum of Normal Weighted Composition Operators on the Fock Space Over C^N

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Acta Mathematica Sinica,English Series 2019年第9期35卷 1563-1572页

作者： Li Xia FENG Lian kuo zhao School of Mathematics and Computer Science Shanxi Normal University

By using commutative C*-algebra techniques, spectrum and essential spectrum of normal weighted composition operators on the Fock space over CN are completely characterized. As an application, spectrum of self-adjoint ... 详细信息

关键词： Fock space weigh ted composition operator normal spectrum

SCC evaluation of a 2297 Al-Li alloy rolled plate using the slow-strain rate technique

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Chinese Journal of Aeronautics 2019年第11期32卷 2516-2525页

作者： kuo zhao Jianhua LIU Mei YU Songmei LI School of Materials Science and Engineering Beihang University

The stress corrosion cracking(SCC) susceptibility of 2297 Al-Li alloy in 1 M Na Cl +0.01 M H2O2 solution(CP solution) and 1 M NaCl + 0.01 M H2O2+ 0.6 M Na2SO4 solution(CPS solution) was investigated by slow-strain rate tests at various strain rates ranging from 10-5s(-1) to 10-7s-1. The roles of H2O2 and SO42-in the corrosion process were estimated by potentiodynamic polarization and electrochemical impedance spectroscopy. 2297 Al-Li alloy does not fracture ascribed to SCC in CP solution, while it undergoes SCC in CPS solution. In CPS solution,with a decreasing strain rate from 10-5s(-1) to 10-7s-1, the SCC susceptibility firstly rises and then declines exhibiting a peak value at a strain rate of 10-6s-1. H2O2 promotes the active dissolution while SO42- lowers the corrosion rate. The SCC fracture is associated with a decline in the dissolution rate of the crack tip by SO42-, which leads to stress concentration. In CPS solution, a reduction in the local dissolution rate of the crack tip leads to stress concentration, resulting in SCC *** the preferred initiation site for a crack, pits also show a noteworthy effect on SCC of 2297 Al-Li alloy.

关键词： Al-Li alloy Dissolution Electrochemical behavior Slow strain rate testing Stress corrosion cracking

Optimization of the Deployment of Temperature Nodes Based on Linear Programing in the Internet of Things

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Tsinghua Science and Technology 2013年第3期18卷 250-258页

作者： Liang Hu Zhengyu Zhang Feng Wang kuo zhao the School of Computer Science and Technology Jilin University

The Internet of Things emphasizes the concept of objects connected with each other, which includes all kinds of wireless sensor networks. An important issue is to reduce the energy consumption in the sensor networks since sensor nodes always have energy constraints. Deployment of thousands of wireless sensors in an appropriate pattern will simultaneously satisfy the application requirements and reduce the sensor network energy consumption. This article deployed a number of sensor nodes to record temperature data. The data was then used to predict the temperatures of some of the sensor node using linear programming. The predictions were able to reduce the node sampling rate and to optimize the node deployment to reduce the sensor energy consumption. This method can compensate for the temporarily disabled nodes. The main objective is to design the objective function and determine the constraint condition for the linear programming. The result based on real experiments shows that this method successfully predicts the values of unknown sensor nodes and optimizes the node deployment. The sensor network energy consumption is also reduced by the optimized node deployment.

关键词： Internet of Things linear programming optimized node deployment energy consumption

Personalized Recommendation Algorithm Based on Preference Features

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Tsinghua Science and Technology 2014年第3期19卷 293-299页

作者： Liang Hu Guohang Song Zhenzhen Xie kuo zhao the School of Computer Science and Technology Jilin University

A hybrid collaborative filtering algorithm based on the user preferences and item features is proposed.A thorough investigation of Collaborative Filtering （CF） techniques preceded the development of this *** proposed algorithm improved the user-item similarity approach by extracting the item feature and applying various item features＇ weight to the item to confirm different item *** preferences for different item features were obtained by employing user evaluations of the *** is expected that providing better recommendations according to preferences and features would improve the accuracy and efficiency of recommendations and also make it easier to deal with the data *** addition,it is expected that the potential semantics of the user evaluation model would be *** would explain the recommendation results and increase accuracy.A portion of the MovieLens database was used to conduct a comparative experiment among the proposed algorithms,i.e.,the collaborative filtering algorithm based on the item and the collaborative filtering algorithm based on the item *** Mean Absolute Error （MAE） was utilized to conduct performance *** experimental results show that employing the proposed personalized recommendation algorithm based on the preference-feature would significantly improve the accuracy of evaluation predictions compared to two previous approaches.

关键词： recommendation system collaborative filtering user preference

Effects of dry/wet ratio and pre-immersion on stress corrosion cracking of 7050-T7451 aluminum alloy under wet-dry cyclic conditions

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Chinese Journal of Aeronautics 2018年第11期31卷 2176-2184页

作者： Mei YU Hang ZU kuo zhao Jianhua LIU Songmei LI School of Materials Science and Engineering Beihang University

The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the effects of dry/wet ratio(DWR) and pre-immersion on *** and side surface characterizations were observed by scanning electron microscopy(SEM).The results demonstrate that SCC susceptibility decreases with an increase of the DWR. With an increase of the pre-immersion time, both continuous pre-immersion(CP) and wet-dry cyclic preimmersion(WDP) samples are more sensitive to SCC, and the cracking mode in the SCC fracture region is intergranular. Furthermore, the effect of WDP on SCC is greater than that of CP when the total time immersed in solution before an SSRT is the same with each other. In fact, each single wetdry cycle can be divided into three processes with respect to the change of solution on samples’ surface. Volatilization of water on the surface results in an increase in solute concentration, thus accelerating corrosion.

关键词： 7050-T7451 aluminum alloy Electrochemical test Pre-immersion Stress corrosion cracking Wet-dry cycle