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Advance in Microwave Photonics

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ZTE Communications 2009年第3期7卷 1-5页

作者： Xie Shizhong,Chen Minghua,Chen Hongwei(tsinghua National Laboratory for Information Science and Technology,department of electronic Engineering,tsinghua {4.,beijing 100084.P.R.china)

Microwave photonics is a combination of microwave and photonics in concepts,devices and *** typical research involves optical generation,processing and conversion of microwave signals,as well as distribution and transmission of microwave signals on optical *** achievements of microwave photonics have promoted the development of some new technologies,including Radio over Fiber (RoF) communication,subcarrier multiplexing and fiber transmission in Cable Television (CATV) system,optical controlled beam forming network with phased array radar and measurement technologies in microwave frequency domain.

关键词： RoF Advance in Microwave Photonics Radio EDFA WDM IEEE high

MANDARIN DIGIT STRING SPEECH RECOGNITION USING LINEAR DISCRIMINANT ANALYSIS AND TONE DISCRIMINATION MODEL

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MANDARIN DIGIT STRING SPEECH RECOGNITION USING LINEAR DISCRI...

2002年IEEE十区计算机、通信、控制和电机工程会议

作者： Yuan-yuan Shi Jia Liu Run-sheng Liu department of electronic Engineering, tsinghua university {4., china, 100084

The acoustic models based on the convenional Hidden MarkovModel have not high recognition performance for the connectedMandarin digit string, because highly confusable syllables *** state-specific linear discriminant analysis is adopted toreduce the substitution errors of confusable digits. Therecognition rate for the isolated digit is increased from 97.16%to 99.32%;and the unknown length digit string from 86.5% to88.18%. Furthermore experiments showing that most of thetypical confusions can be discriminated by the pitch contourpatterns the tone discrimination models are trained and the two-pass recognition algorithm to combine the acoustic modellikelihood and the tone discrimination model likelihood isdeveloped. By tone discrimination the relative digit string errorrate is reduced by 37.4.. The unknown length digit stringrecognition rate and its digit recognition rate are increased from88.18% and 97.54. to 92.6% and 98.21%. respectively.

关键词： MANDARIN DIGIT STRING SPEECH RECOGNITION USING LINEAR DISCRIMINANT ANALYSIS AND TONE DISCRIMINATION MODEL

Selecting HMM state numbers for initial semi-syllables in continuous Mandarin Speech Recognition of Human-Machine intercommunion

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Selecting HMM state numbers for initial semi-syllables in co...

第一届建立和谐人机环境联合学术会议（HHME2005）

作者： HE JUE2, LIU JIAtsinghua university department of electronic Engineering {4. 100084.0} university department of electronic Engineering {4. 100084

In this paper, a new criterion is proposed to select the HMM state numbers for initial semi-syllables in continuous Mandarin speech recognition. The new criterion is synthetically composed of each ini

关键词： HMM state number initial semi-syllable Human-Machine intercommunion Duration

OXIDATIVE COUPLING OF METHANE OVER Na2O-La2O3/BaCO3 CATALYSTS

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Journal of Energy Chemistry 1994年第2期 150-155页

作者： Q1U Xian-Qing ZHANG Mei-Zhen ZHU Qi-Ming department of Chemistry, tsinghua university beijing 100084

The oxidative coupling of methane over various alkali metal oxidespromoted LaOO/BaCOcatalysts and the effects of NaO content on the performance of NaO-LaO/BaCOcatalyst have been *** was found thatNaO promoted LaCO/BaCOcatalyst showed advantages of high CHconver-sion,Cselectivity and CH/CHratio,NaO might affect the properties ofcatalyst through elctronic and geometric *** highest Cyield（19.0一20.6%）over Na-9wt%LaO/BaCOcatalysts was obtained in the NaOcontent range of 1.0—3.0%.Effects of reaction conditions on OCM over3wt% NaO-9wt%LaCO/BaCOcatalyst were also *** catalystswere characterized by BET,TPD,and *** studies on 3wt% NaO-9wt%LaO/BaCOcatalyst demonstrated that CO,*** bestrongly on the *** might be related to the activation of CHand theformation and reseneration of active oxygen soecies.

关键词： Na La OXIDATIVE COUPLING OF METHANE OVER Na2O-La2O3/BaCO3 CATALYSTS

Preparation,Characterization and Applications of Titanate/Titania Nanocrystals

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稀有金属材料与工程 2006年第S3期 638-641页

作者： Junrong Li~(1,2) Zilong Tang~1 Zhongtai Zhang~1 Zhigang Zhou~1 (1.State Key Laboratory of New Ceramics and Fine Processing,department of Materials Science and Engineering,tsinghua university,beijing 100084.{4.) (2.beijing Institute of Space Medico-Engineering,beijing 100094.{4.)

The present paper focused on the preparation of hydrogen titanate nanotubes and nanowires and their conversion into titania by heat *** structural,morphology and optical properties of as-prepared nanostructured titanate and titania were investigated by transmission electron microscopy (TEM),X-ray diffraction (XRD) and diffusive reflectance *** slim diameter of these nanostructured titanate and titania,the versatile crystal structure and special optical and electronic properties may make them find versatile applications in chemical sensors for multiple purposes.

关键词： titanate titania nanocrystals preparation applications

Adaptive Admission Control for QoS Services in OFDM-MIMO Networks

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Adaptive Admission Control for QoS Services in OFDM-MIMO Net...

The 19th International Teletraffic Congress-ITC19

作者： LI Lei and NIU Zhisheng tsinghua-Hitachi Joint Lab on Ubiquitous IT department of electronic Engineering tsinghua {4. 100084.beijing P. R. china

＜正＞In this paper, we develop a resource allocation and admission control scheme for multimedia services downlink transmission in a multiple parallel time-varying subchannels circumstance such as that in current orthogonal frequency division multiplexing （OFDM） and multi-input multi-output （MIMO） systems. We introduce the outage probability to characterize the influence of both the bursty nature of multimedia traffic and the uncertainty of wireless capacities on resource allocation and then correlate it to the connection dropping probability factor in the quality-of-service （QoS） requirements. In order to utilize the scarce wireless resource efficiently, as many users as possible should be admitted into the network while providing guaranteed QoS support for them. By integrated multiuser diversity and space-frequency diversity scheduling, we analysis the outage probabilities under the current proportional fair scheduling algorithm. By simulation results, superiorities in system utilization efficiency of our scheme are verified.

关键词： Radio resource management admission control scheduling orthogonal frequency division multiplexing (OFDM) multi-input multi-output (MIMO).

Design of Lowering the Error Floors of LDPC Codes

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Design of Lowering the Error Floors of LDPC Codes

2005全球移动通信大会

作者： wang Ruihua Yin Liuguo Yu Quan Communication engineering college PLA Science and technology university. Nanjing 210007 china department of {4. Engineering tsinghua university beijing 100084.china china {4. equipment system engineering corporation beijing 100039 china

＜正＞Aiming at the requirement of very low bit error rate （BER） output in the new generation multimedia transmission system and storage system, a concatenated code construction scheme for low-error-floor low-density parity-check （LDPC） codes is proposed in this paper. The inner code of this scheme is low rate LDPC code that is generated randomly, which is used to correct channel error;the outer code of this scheme is high rate finite geometry LDPC code, which is used to correct residual error. Simulation result shows that this concatenated coding scheme can effectively eliminate the error floor and meet the requirement of the high reliability transmission system.

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ON MULTICAST TREE CONSTRUCTION IN IPV4.IPV6 HYBRID NETWORK

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Journal of electronics(china) 2010年第3期27卷 398-404页

作者： Zhang Chao Zhang Yuan Huang Yongfeng Li Xing New Generation Network Lab Department of Electronic Engineering Tsinghua University Beijing 100084 China

With the IPv4.addresses exhausting and IPv6 emerging, the Peer-to-Peer (P2P) overlay is becoming increasingly heterogeneous and complex: pure IPv4. dual stack and pure IPv6 hosts coexist, and the connectivity limitation between IPv4.and IPv6 hosts requires the overlay protocols to be fit for this hybrid situation. This paper sets out to answer the question of how to construct multicast tree on top of IPv4.IPv6 hybrid network. Our solution is a New Greedy Algorithm (NGA) which eliminates the problem of joining failure in the hybrid network and keeps the efficiency of greedy algorithm in tree construction. Simulation results show that our algorithm has excellent performance, which is very close to the optimal in many cases.

关键词： IPv6 Peer-to-Peer (P2P) Multicast tree

A brief review on the recent development of phonon engineering and manipulation at nanoscales

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International Journal of Extreme Manufacturing 2024年第1期6卷 177-206页

作者： Siqi Xie Hongxin Zhu Xing Zhang Haidong wang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

Phonons are the quantum mechanical descriptions of vibrational modes that manifest themselves in many physical properties of condensed matter systems. As the size of electronic devices continues to decrease below mean free paths of acoustic phonons, the engineering of phonon spectra at the nanoscale becomes an important topic. Phonon manipulation allows for active control and management of heat fow, enabling functions such as regulated heat transport. At the same time, phonon transmission, as a novel signal transmission method, holds great potential to revolutionize modern industry like microelectronics technology, and boasts wide-ranging applications. Unlike fermions such as electrons, polarity regulation is difficult to act on phonons as bosons, making the development of effective phonon modulation methods a daunting *** work reviews the development of phonon engineering and strategies of phonon manipulation at different scales, reports the latest research progress of nanophononic devices such as thermal rectifiers, thermal transistors, thermal memories, and thermoelectric devices,and analyzes the phonon transport mechanisms involved. Lastly, we survey feasible perspectives and research directions of phonon engineering. Thermoelectric analogies, external field regulation, and acousto-optic co-optimization are expected to become future research hotspots.

关键词： phonon engineering phononic device nanoscale