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Improvement of LDA model with time factor for collaborative filtering

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The Journal of China Universities of Posts and Telecommunications 2019年第6期26卷 54-62页

作者： yao wenbin Hu Fangyi Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia Beijing University of Posts and TelecommunicationsBeijing 100876China National Engineering Laboratory for Mobile Network Beijing University of Posts and TelecommunicationsBeijing 100876China

Collaborative filtering(CF) is one of the most widely used Algorithm in recommender systems, which help users obtain the information they may like. We proposed a latent Dirichlet allocation(LDA) model combining time and rating(TR-LDA) for CF. We use mathematical methods to fit the Ebbinghaus forgetting curve in our method and introduce time weights based on time window to find out the impact of time on user’s interests. The user’s choice of items is not only influenced by his/her interests, but also influenced by other’s rating. According to the users’ feedback, we find their rating distribution on items under the interests. Finally, experimental results on real data sets MovieLens 100 k and MovieLens 1 M show that the proposed Algorithm can predict the user implicit interests effectively and improve the recommendation performance.

关键词： CF LDA forgetting curve time window feedback

Keyword Extraction for Contextual Advertising

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China Communications 2010年第4期7卷 51-57页

作者： LIU Jianyi WANG Cong yao wenbin National Engineering Laboratory for Disaster Backup and Recovery Beijing University of Posts and Telecommunications Beijing 100876 China

Contextual advertising is a major revenue source for today’s *** extraction is a key step in this kind of advertising,through which appropriate

关键词：网页广告互联网计算机技术

QoS-oriented packet scheduling scheme for opportunistic networks

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The Journal of China Universities of Posts and Telecommunications 2017年第3期24卷 51-57页

作者： yao wenbin Chen Yin Zong Ming Wang Dongbin Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia Beijing University of Posts and Telecommunications School of Computer Science Beijing University of Posts and Telecommunications Yingcai Honors College University of Electronic Science and Technology of China National Engineering Laboratory for Mobile Network Security Beijing University of Posts and Telecommunications

The unique characteristics of opportunistic networks （ONs）, such as intermittent connectivity and limited network resources, makes it difficult to support quality of service （QoS） provisioning, particularly to guarantee delivery ratio and delivery delay. In this paper, we propose a QoS-oriented packet scheduling scheme （QPSS） to make decisions for bundle transmissions to satisfy the needs for the delivery ratio and delivery delay constraints of bundles. Different from prior works, a novel bundle classification method based on the reliability and latency requirements is utilized to decide the traffic class of bundles. A scheduling algorithm of traffic class and bundle redundancy is used to maintain a forwarding and dropping priority queue and allocate network resources in QPSS. Simulation results indicate that our scheme not only achieves a higher overall delivery ratio but also obtains an approximate 14% increase in terms of the amount of eligible bundles.

关键词： opportunistic networks packet scheduling QoS traffic class of bundles

ESSA： An Efficient and Secure Splitting Algorithm for Distributed Storage Systems

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China Communications 2010年第4期7卷 89-95页

作者： CHEN Zhao yao wenbin XIAO Da WU Chunhua LIU Jianyi WANG Cong National Engineering Laboratory for Disaster Backup and Recovery Beijing University of Posts and Telecommunications Beijing 100876 China

The security of critical data is an important issue for distributed storage system design,especially for long-term *** (An Efficient and Secure Splitting Algorithm for Distributed Storage Systems) is presented,which takes advantage of a two level information dispersal scheme to strengthen the security of *** ESSA,the approach of knight’s tour problem,which is NP-Complete,is introduced to scramble data at the first level,and a split cube is used to split scrambled data at the second ***,it is very difficult for the malicious user to get information because the task of reconstructing the original data needs more computation than they can *** prove that the security of ESSA is better than encryption algorithm and not inferior to erasure codes and secret *** results show that distributed storage systems exploiting ESSA has greater efficiency than that exploiting keyed encryption,erasure codes and secret sharing.

关键词：存储系统安全性安全技术通信技术

A novel topology with controllable wideband baseband impedance for power amplifiers

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Frontiers of Information Technology & Electronic Engineering 2024年第2期25卷 308-315页

作者： yao yao Zhijiang DAI Mingyu LI School of Intelligent Technology and Engineering Chongqing University of Science and TechnologyChongqing400065China School of Microelectronics and Communication Engineering Chongqing UniversityChongqing400065China

This paper presents a novel topology to control the baseband impedance of a power amplifier(PA)to avoid performance deterioration in concurrent dual-band *** topology can avoid pure resonance of capacitors and inductors LC,which leads to a high impedance at some frequency ***,it can be applied to transmitters that are excited by broadband *** particular,by adjusting the circuit parameters and increasing stages,the impedance of the key frequency bands can be flexibly controlled.A PA is designed to support this design *** saturated output power is around 46.7 dBm,and the drain efficiency is>68.2%(1.8-2.3 GHz).Under concurrent two-tone excitation,the drain efficiency reaches around 40%even under 5.5 dB back-off power with the tone spacing from 10 MHz to 500 *** results demonstrate that the proposed topology is capable of controlling wideband baseband impedance.

关键词： Baseband impedance Concurrent dual-band Power amplifier

Fresh-Keeping Decision and Coordination of Fresh Agricultural Product Supply Chain Considering Carbon Cap-and-Trade under Different Dominance

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Journal of Systems Science and Systems Engineering 2024年第1期33卷 30-51页

作者： Yang Yang Guanxin yao China Institute for Agricultural Equipment Industrial Development Jiangsu UniversityZhenjiang212013China Jiangsu Modern Logistics Research Base Yangzhou UniversityYangzhou225009China

In the context of low carbon,this paper discussed the impact of the carbon cap-and-trade policy on the fresh-keeping decision-making of two-echelon fresh agricultural product supply chains under different dominance,and designed cost-sharing contracts to coordinate the supply chain of fresh agricultural products dominated by suppliers and retailers *** results showed that:dominance has no effect on the fresh-keeping decision and total revenue of fresh agricultural product supply chain,but it affects the internal income distribution,and dominance does not always bring more benefits;the implementation of carbon cap-and-trade reduces the fresh-keeping decision-making of fresh agricultural products supply chain and reduces the free-rider income of followers;the role of higher carbon trading price is twofold,which not only brings about the speculation of leading enterprises,but also promotes the application of low-carbon technologies;consumers’high preference for freshness,low-cost and high-efficiency low-carbon technology are all conducive to improving the fresh-keeping efforts and benefits of the supply chain;cost-sharing contracts can coordinate the supply chain of fresh agricultural products.

关键词： Dominant power carbon cap-and-trade policy fresh agricultural product supply chain fresh-keeping decision-making

Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO_(2)fracturing

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Particuology 2024年第7期90卷 149-163页

作者： Boyu Liu Jun yao Research Center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical CO_(2)(Sc-CO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-CO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-CO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： CFD-DEM Heat transfer Compressible fluid CO_(2)sequestration Proppant transport

Limits of Uneven Battery Power in Modular Multilevel Converter-based Battery Energy Storage Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 686-695页

作者： yao Pan Xiaofeng Sun Wei Zhao Xin Li yao Cai Institute of Electrical Engineering Yanshan UniversityQinhuangdao 066004China

For modular multilevel converter-based battery energy storage systems (MMC-BESS), uneven power among batteries of SMs will be deduced by battery aging, battery fault, etc., which will degrade performance and even lead to system failure. For maintaining the balance of capacitor voltage, this paper analyzes the limits of the uneven power of batteries, which are presented as the current limits in this paper. According to analysis, an analytical method is proposed that only the dc and fundamental frequency components of the arm current are used to calculate current limits. With the current limits it is able to evaluate the reasonability of power distribution among batteries. Meanwhile, increase of fundamental frequency component will enhance the current limits, and the dc component determines the size relationship between the absolute values of the upper and lower current limits. Finally, simulation model and experiment prototype are built for verifying the theoretical analysis and current limits calculation method, and satisfactory results are provided.

关键词： Arm current balance of capacitor voltage current limits MMC-BESS uneven power

A New Software Reliability Framework —— A Extended Cleanroom Model

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High Technology Letters 2001年第2期7卷 42-46页

作者：姚文斌 Dept. of Computer Science and Eng. Harbin Institute of Technology Harbin 150001 China

Cleanroom software engineering has been proven effective in improving software development quality while at the same time increasing reliability. To adapt to large software system development, the paper presents an extended the Cleanroom model, which integrates object-oriented method based on stimulus history, reversed engineering idea, automatic testing and reliability assessment into software development. The paper discusses the architecture and realizing technology of ECM.

关键词： Cleanroom model Stimulus history Object-oriented method Reversed engineering Automatic testing Reliability assessment