The Progress of P2P IPTV

1 Limitation of IPTV System with Client/Server Architecture IPTV services generally refer to theaudio/video contents transmittedthrough IP networks and received byTV. At present, telecom operatorsuse the manageable IP networkssupporting multicast to offer IPTVservices, including Live TV, Time- shiftedTV, Video on Demand (VOD) andinteractive data services.IPTVsystems in China are adoptingthe client/server architecture to offerunicast and on- demand (includes VoDand Time- shifted…     

Design and rapid prototyping of SCA-compliant public safety P25 waveform and P25?CFM3TR?CVoIP bridge

Establishing radio communication between military commanders, soldiers and law enforcement officers is an important enabling capability to facilitate interoperability. The Joint Tactical Radio System (JTRS) program is enabling communications within the military by implementing different military radio waveforms on software defined radio (SDR) platforms. It is logical to include a Project 25 (P25) public safety waveform in the JTRS waveform portfolio. This paper describes the rapid development of a P25 waveform on a surrogate JTRS SDR platform. The development process and methodology, which starts from a platform agnostic executable waveform model in Matlab, through an intermediate implementation using open tools on generic platforms, to the final platform-specific implementation, is introduced and discussed. This paper shows that adopting this methodology can speed up waveform development and porting. Furthermore, this paper presents the design and implementation of a three way voice bridge among P25, the future multiband multiwaveform modular tactical radio (FM3TR), and voice over Internet Protocol (VoIP), with software communication architecture (SCA) compliant implementation for both the P25 and FM3TR waveforms. This paper shows that critical issues such as interoperability can be tackled efficiently by leveraging SDR and SCA.     

Leakage current,active power,and delay analysis of dynamic dual Vt CMOS circuits under P–V–T fluctuations

The leakage current, active power and delay characterizations of the dynamic dual V_t CMOS circuits in the presence of process, voltage, and temperature (P–V–T) fluctuations are analyzed based on multiple-parameter Monte Carlo method. It is demonstrated that failing to account for P–V–T fluctuations can result in significant reliability problems and inaccuracy in transistor-level performance estimation. It also indicates that under significant P–V–T fluctuations, dual V_t technique (DVT) is still highly effective to reduce the leakage current and active power for dynamic CMOS circuits, but it induces speed penalty. At last, the robustness of different dynamic CMOS circuits with DVT against the P–V–T fluctuations is discussed in detail.     

The School of Software Engineering ,Beijing University of Posts and Telecommunications

Established on October18th of2002,the School of Soft-ware Engineering of Beijing University of Posts andTelecommunications is one of the35national model schoolsof software engineering approved bythe Ministry of Educa-tion and the National Committee of Development and Re-form.According to current requirements and internationaltrends,the school has set upits objective as to educate stu-dents with multi-level,practical,and composition talents.To this end,the school has established dynamic an…     

Transmission of neutron and γ-irradiated fused quartz,crystalline quartz,teflon, polyethylene and TPX at mm- and sub-mm wavelengths

The transmission of fused and crystalline quartz, teflon, polyethylene and TPX was measured at mm- and sub-mm-wavelengths after neutron and γ-irradiation of the samples at doses comparable with typical values for vessel windows in ignited fusion experiments. Whereas fused and crystalline quartz and — with some restriction —teflon and polyethylene retained their transparency even after such extreme exposures, the transmission of TPX was degraded by irradiation doses one or two orders of magnitude below those expected for such experimental conditions.     

The School of Software Engineering,Beijing University of Posts and Telecommunications

Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of Education and the National Committee …     

The School of Software Engineering ,Beijing University of Posts and Telecommunications

Established on October18th of 2002,the School of Soft-ware Engineering of Beijing University of Posts andTelecommunications is one of the35national model schoolsof software engineering approved bythe Ministry of Educa-tion and the National Committee of De…     

Synthesis and Measurement of the Thermoelectric Properties of Multiphase Composites: ZnSb Matrix with Zn4Sb3, Zn3P2, and Cu5Zn8

We synthesized a series of samples with composition around 52 at.% zinc (Zn), 44 at.% antimony (Sb), 4 at.% phosphorus (P), and up to 3 at.% copper (Cu) by melting the elements and subsequent annealing. This resulted in dense and almost crack-free samples. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) revealed composites with a majority phase of ZnSb containing varying amounts of Zn₃P₂ and Cu₅Zn₈, in addition to Zn₄Sb₃ in some of the samples. We measured the Seebeck coefficient, electrical conductivity, and thermal conductivity as a function of temperature. The thermoelectric performance tended to improve with increasing Cu content. At Cu content of 2 at.%, a reduced resistivity allows for the highest dimensionless figure of merit, with a maximum zT value of 0.18 at around 573 K.     

Design,Analysis,and Optimization of a CMOS Active Pixel Sensor

设计了一个三管有源像素和其用开关电容放大器实现的双采样读出电路. 该电路被嵌入一64×64像素阵列CMOS图像传感器，在Chartered公司0.35μm工艺线上成功流片. 在8μm×8μm像素尺寸下实现了57%的填充因子. 测得可见光响应灵敏度为0.8V/(lux·s)，动态范围为50dB. 理论分析和实验结果表明随着工艺尺寸缩小，像素尺寸减小会使光响应灵敏度降低. 在深亚微米工艺条件下，较深的n阱/p衬底结光电二极管可以提供合理的填充因子和光响应灵敏度.     

Design and Characterization of Fabry–Pérot MEMS-Based Short-Wave Infrared Microspectrometers

Microspectrometers based on the monolithic integration of a microelectromechanical system (MEMS) Fabry–Pérot filter and a Hg _x Cd_1–x Te-based infrared detector are discussed and measured results presented. The microspectrometers are designed to operate in the 1.5 μm to 2.6 μm wavelength range. Design equations are presented which account for the mechanical and optical characteristics of the device. Measurements indicate linewidths as narrow as 55 nm, switching times of 40 μs, and a tuning range of 380 nm, which is limited by snap-down. Optical characterization of the distributed Bragg mirrors and the Fabry–Pérot filter are presented, and these are shown to be in good agreement with simple first-order analytical models. Bowing of the movable Fabry–Pérot mirror due to stress gradients is identified as the dominant source of linewidth broadening.     

Application of the Appraisal Activities of the Products,Techniques and Applications Projects of BIRTV

Name of the ItemChinese‘EnglishTyPe of APPlieation口Audio Produetion and Broadeast口Video Produetion and Broadeast口Radio and Television Transmission and Delivery口Information Engineering口Film production,Projeetion and Distribution.The ProPertiesof the Item口Produets TyPe口Technieal TyPe口APplieation TypeProduetioll Unit of theItem DeveloPerReeonlnlexldation Unit ofthe Item APPlieaitonLiasion PersonnelTel.E一mailZIP CodeAdd.Of the APPlyingUnitOther necessary materials…     

Electronic structures and phase transition characters of β-, P61-, P62-and δ-Si3N4 under extreme conditions: a density functional theory study

This paper describes the results of structural, electronic and elastic properties of silicon nitride(in its high-pressure P61 and P62 phases) through the first-principles calculation combined with an ultra-soft pseudopotential. The computed equilibrium lattice constants agree well with the experimental data and the theoretical results. The strongest chemical bond(N–Si bond) shows a covalent nature with a little weaker ionic character. P61-Si3N4 is more stable than P62-Si3N4 due mainly to the fact that the shorter N–Si bond in the P61 phase allows stronger electron hybridizations. We have also predicted the phase stability of Si3N4 using the quasi-harmonic approximation, in which the lattice vibration and phonon effect are both considered. The results show that the β→P61 phase transition is very likely to occur at 42.9 GPa and 300 K. The reason why the β→P61→δ phase transitions had never been observed is also discussed.     

Resonance states, heavy quasiparticles, and the thermoelectric figure of merit of IV–VI materials

A high thermoelectric figure of merit ZT, with a maximum value ZT = 1.5 at 670?C800 K for the composition Ge_0.9Pb_0.05Bi_0.05Te, has been obtained for GeTe solid solutions with Bi and Pb impurities. This is conducive to a decrease in the hole concentration, an increase in the Seebeck coefficient, and a decrease in the lattice thermal conductivity. The main attention in interpretation of the experimental data is given to specific features of the energy spectrum of holes in the initial GeTe compound. The model of resonance states, formed with involvement of Ge atoms and metal vacancies, has been further developed. The types of defects and their transformation depending on temperature and the concentration of superstoichiometric Te have been considered. The experimental results give reason to believe that the interaction of localized and free charge carriers at elevated temperatures leads to a pronounced hybridization of their states and the formation of heavy quasiparticles, a situation in many ways similar to that observed in materials with heavy fermions.     

Data Service: Characteristics, Market Structure, and the Role of Operator

1　Introduction　Since the development of telecommunication technologymake the operator able to offer data service to subscribers inthe mid 1990s, operators of various countries have madeenormous efforts to develop data service. Currently, the ar gument on 3G ( 3rd Generation, International MobileTelecommunications 2000) focuses on how to find, develop,and popularize application services in data service markettoo. Some researchers propose that even NTT DoCoMo can n…     

Business Models,Operation Models and Service Development of IPTV

By 2005, the world had seen thetransition ofIPTVservices fromexperiment to commercialrollouton one network after another.Over 30 telecommunications operatorshave launched IPTVservices across theglobe and among them, France Telecomhas the most subscribers, reportedlyhundreds ofthousands. According to theestimation ofMRG, a multimediaresearch group based in California,globalIPTVsubscribers willgrow from734 thousand of2004 to 13 500 thousandthrough 2007. The related revenue willberising to…     

Endogenous Innovation, the Organization of Work and Institutional Context

Drawing on the results of the third Community Innovation Survey and the third European Working Conditions Survey, this paper develops aggregate indicators at the national level of innovation modes and forms of work organization for the 15 member nations of the European Union in 2000. The analysis based on these indicators demonstrates that there is a close connection between how people work and learn in a country and the way firms＇ innovate. Specifically, it shows that in nations where work is organized to support high levels of discretion in solving complex problems firms tend to be more active in terms of endogenous innovation, i.e. innovation developed, at least to some degree, in house. In countries where learning and problem-solving on the job are more constrained, and little discretion is left to the employee, firms tend to engage in a supplier-dominated innovation strategy. The technological renewal of these firms reflects, almost exclusively, absorption of innovations developed elsewhere.     

The review forms of the Appraisal Activities of the Products,Techniques and Applications Projects of BIRTV

ChineseName of the ItemEnglishTyPe of APPlication口Audio produetion and Broadcast口Video Produetion and Broadeast口Radio and Television Transmission and Delivery口Information Engineering口Film Produetion,Projection and DistributionThe ProPertiesof the Item口Products TyPe口Teehnieal Type口Application TypeReview OPinion on theAPPlied MaterialsOPinions of Prelimi-nary Examination forthe ItemOPinions ofRe一Exall刀-nation for the ItemOPinions of the FinalExamination for theItem…     

Atomic and electronic structure of the silicon and silicon-metal Si20, Si 20 − , NaSi20, KSi20 nanoparticles

The results of atomic-structure optimization and calculation of the electronic structure of the Si₂₀, Si ₂₀ ^? , NaSi₂₀, and KSi₂₀ clusters are reported. The PM3 and AM1 semiempirical methods were used in the calculations. It is shown that the Na and K atoms stabilize the fullerene-like silicon structure. The effect of configuration of the clusters on their electronic structure is analyzed.