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Property T and strong property T for unital*-homomorphisms

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Frontiers of Mathematics in China 2020年第2期15卷 385-398页

作者： Qing meng School of Mathematical Sciences Qufu Normal UniversityQufu 273165China

We introduce and study property T and strong property T for unital*-homomorphisms between two unital C^*-*** also consider the relations between property T and invariant subspaces for some canonical unital^-*** a corollary,we show that when G is a discrete group,G is finite if and only if G is amenable and the inclusion map i:Cr^*(G)→B(l^2(G))has property *** also give some new equivalent forms of property T for countable discrete groups and strong property T for unital C^*-algebras.

关键词： Unital*-homomorphism unital C^*-algebra *-bimodule property T strong property T

Insight into deformation allocation in the multi-pass roll forming of a double-walled brazed tube

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Advances in Manufacturing 2023年第4期11卷 567-586页

作者： meng-meng Liu Yu-Li Liu Heng Li State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an710072People’s Republic of China

Deformation allocation is an important factor that affects 720°curling forming from copper-coated steel strips to double-walled brazed tubes(DWBTs).In this study,four schemes of deformation allocation,considering different weights of the total feed distance,are proposed,and a 3D finite element(FE)model of the multi-pass roll forming process for DWBT is developed and verified to investigate the cross-sectional evolution and deformation *** results show the following.(i)In the 720°curling forming process from the steel strip into double-walled tubes,the curvature of the formed circular arc initially increases and then remains stable with roll forming,and the inner and outer tubes of the DWBT are formed in the third and fifth forming *** forming can eliminate the gap between the double walls and improve the overall roundness.(ii)For different deformation allocations,the cross-sectional profiles of the roll-formed parts exhibit a discrepancy,and the deformation amount varies with the roll-forming *** deformation amount in Scheme three is the maximum,and the cross-sectional profile deviates significantly from the ideal shape and fails to form a DWBT,which indicates that the deformation allocation is unsuitable.(iii)The roundness of the outer tube is better than that of the inner ***,the roundness of the inner tube is the key to restricting the forming accuracy of the *** with Schemes one and two,Scheme four with a linear allocation of the total feed distance exhibits the best roundness,and the deformation allocation is reasonable;i.e.,when the contact points between the rollers and steel strip are in a straight line,the roundness of the DWBT is in good agreement with the ideal condition.

关键词： Double-walled brazed tube(DWBT) Multi-pass roll forming Deformation allocation Cross-sectional profile Roundness

Flex Ethernet Technology and Application in 5G Mobile Transport Network

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China Communications 2021年第2期18卷 250-258页

作者： meng Zhang Research Institute of Telecommunications Transmission(RITT) China Academy of Information Communications Technology(CAICT)MIITBeijing 100191China

With the advent of 5G era,the rise of cloud services,virtual reality/virtual reality(AR/VR),vehicle networking and other technologies has put forward new requirements for the bandwidth and delay of the bearer *** Ethernet technology cannot meet the new requirements very *** Ethernet(FlexE)technology has emerged as the times *** paper introduces the background,standardization process,functional principle,application mode and technical advantages of FlexE technology,and finally analyses its application prospects and shortcomings in 5G mobile transport network.

关键词： Flex Ethernet(FlexE) 5G mobile transport network network slicing

Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates

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Journal of University of Science and Technology Beijing 2005年第5期12卷 385-389页

作者： Yuqun meng Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching （FGIAL）, enhanced agitation alkali-leaching （EAAL）, thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arse- nides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.

关键词： refractory gold-bearing arsenosulfide concentrates pretreatment alkaline leaching self-leaching of gold thiosulfate leaching

Summary of research on recommendation system based on serendipity

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The Journal of China Universities of Posts and Telecommunications 2022年第4期29卷 89-105页

作者： meng Wei Wang Liting Lümeng School of Information Science and Technology Beijing Forestry UniversityBeijing 100083China Engineering Research Center for Forestry-oriented Intelligent Information Processing National Forestry and Grassland AdministrationBeijing 100083China

Personalized recommender systems provide various personalized recommendations for different users through the analysis of their respective historical ***,the problem of the“filter bubble”which has to do with over-specialization ***(SRDP),one of the evaluation indicators,can provide users with unexpected and useful recommendations,and help to successfully mitigate the filter bubble problem,and enhance users’satisfaction levels and provide them with diverse *** SRDP is highly subjective and challenging to study,only a few studies have focused on it in recent *** this study,the research results on SRDP were summarized,the various definitions of SRDP and its applications were discussed,the specific SRDP calculation process from qualitative to quantitative perspectives was presented,the challenges and the development directions were outlined to provide a framework for further research.

关键词： serendipity recommended algorithm recommended diversity filter bubbles evaluation indicators

机器学习在智能反射面辅助的通信系统中的应用综述

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北京工业大学学报 2025年第1期51卷 87-99页

作者：司鹏搏李双缘刘畅李萌北京工业大学信息学部北京100124 先进信息网络北京实验室北京100124

智能反射面(intelligent reflecting surfaces,IRS)可以通过大量低成本的无源反射元件巧妙地调整信号反射,从而动态改变无线信道,提高通信性能,目前已成为无线通信研究的焦点。然而,由于IRS的加入,整个通信系统变得更加复杂,系统的动态... 详细信息

智能反射面(intelligent reflecting surfaces,IRS)可以通过大量低成本的无源反射元件巧妙地调整信号反射,从而动态改变无线信道,提高通信性能,目前已成为无线通信研究的焦点。然而,由于IRS的加入,整个通信系统变得更加复杂,系统的动态性也更高,使通信系统面临着许多新的挑战。机器学习(machine learning,ML)具有很强的数据处理与自适应能力,能够不断适应变化的环境和需求,可以很好地应对通信系统中的许多挑战。因此,使用ML解决IRS辅助的通信系统中的问题,已经成为当前研究的重点。基于此,对ML在IRS系统中的应用进行了系统性的概述,从IRS辅助的通信系统中存在的问题入手,分别从反射因子的设计与优化、信道处理与建模、资源分配和管理、安全性增强4个方面对ML在IRS系统中的应用进行阐述和分析,并讨论了将ML应用在IRS系统中的优势及未来的发展趋势与挑战。

关键词：智能反射面(intelligent reflecting surfaces,IRS) 无线通信反射因子信道资源分配通信安全机器学习(machine learning,ML)

Optimal restructuring strategies under various dynamic factors

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第6期8卷 932-938页

作者： meng Qing-xuan Department of Management Science and Engineering Stanford University CA 94305 USA College ofEconomtcs Zhejiang University Hangzhou 310027 China

Corporate restructuring was identified as a new industrial force that has great impact on economic values and that therefore has become central in daily financial decision making. This article investigates the optimal restructuring strategies under different dynamic factors and their numerous impacts on firm value. The concept of quasi-leverage is introduced and valuation models are built for corporate debt and equity under imperfect market conditions. The model’s input variables include the quasi-leverage and other firm-specific parameters, the output variables include multiple corporate security values. The restruc- turing cost is formulated in the form of exponential function, which allows us to observe the sensitivity of the variation in security values. The unified model and its analytical solution developed in this research allow us to examine the continuous changes of security values by dynamically changing the coupon rates, riskless interest rate, bankruptcy cost, quasi-leverage, personal tax rate, corporate taxes rate, transaction cost, firm risk, etc., so that the solutions provide useful guidance for financing and restructuring decisions.

关键词： Restructuring Capital structure Financial decisions

Effects of COD/N ratio and DO concentration on simultaneous nitrification and denitrification in an airlift internal circulation membrane bioreactor

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Journal of Environmental Sciences 2008年第8期20卷 933-939页

作者： meng Qingjuan Yang Fenglin Liu Lifen meng Fangang Dalian Univ Technol Sch Environm & Biol Sci & Technol MOE Key Lab Ind Ecol & Environm & Engn Dalian 116024 Peoples R China Tech Univ Berlin Dept Chem Engn D-10623 Berlin Germany

The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic *** results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N *** the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...

关键词： simultaneous nitrification and denitrification(SND) chemical oxygen demand and nitrogen(COD/N)ratio dissolved oxygen(DO)concentration

Fault self-repair strategy based on evolvable hardware and reparation balance technology

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Chinese Journal of Aeronautics 2014年第5期27卷 1211-1222页

作者： Zhang Junbin Cai Jinyan meng Yafeng meng Tianzhen Department of Electronic and Optical Engineering Mechanical Engineering College

In the face of harsh natural environment applications such as earth-orbiting and deep space satellites, underwater sea vehicles, strong electromagnetic interference and temperature stress,the circuits faults appear easily. Circuit faults will inevitably lead to serious losses of availability or impeded mission success without self-repair over the mission duration. Traditional fault-repair methods based on redundant fault-tolerant technique are straightforward to implement, yet their area, power and weight cost can be excessive. Moreover they utilize all plug-in or component level circuits to realize redundant backup, such that their applicability is limited. Hence, a novel selfrepair technology based on evolvable hardware（EHW） and reparation balance technology（RBT） is proposed. Its cost is low, and fault self-repair of various circuits and devices can be realized through dynamic configuration. Making full use of the fault signals, correcting circuit can be found through EHW technique to realize the balance and compensation of the fault output-signals. In this paper, the self-repair model was analyzed which based on EHW and RBT technique, the specific self-repair strategy was studied, the corresponding self-repair circuit fault system was designed, and the typical faults were simulated and analyzed which combined with the actual electronic devices. Simulation results demonstrated that the proposed fault self-repair strategy was feasible. Compared to traditional techniques, fault self-repair based on EHW consumes fewer hardware resources, and the scope of fault self-repair was expanded significantly.

关键词： Evolutionary algorithm Evolvable hardware Fault Self-repair Fault-tolerant Genetic algorithm particle swarm optimization Reparation balance technology