浅析降低IPTV用户质差率的有效措施

随着多媒体行业的领先发展,我国视频媒体得到了充分的推广和应用。IPTV是在电视技术的基础上为其增加网络服务系统,使得系统更加强大的一种智能化视频技术,并在现代社会中得到了广泛应用。但是,目前的IPTV业务质差较大,影响用户正常使用,也阻碍IPTV技术的继续发展。因此,本文主要从技术和网络结构等方面,探究IPTV质差大的原因以及降低质差的有效措施。

基于用户感知的IPTV端质量评估体系研究及实现

为了解决IPTV业务视频质量用户体验差、投诉率高等问题,提出建立IPTV端到端视频质量评估体系,该体系在确定合理的量化指标的基础上,依靠IPTV质量监测分析系统,主动感知业务质量劣化,实时监控网络性能,将业务质量与网络性能关联,实现群障主动预防、故障快速定界。通过在某省电信网络中的应用,故障定位准确,预判能力整体提升,质差率明显下降,市场优势明显,抢占了市场先机。

IPTV端到端网络优化策略研究

随着IPTV用户规模高速增长、高清和4K视频节目源不断增多,传统通信网络承载大流量、高速率视频业务逐渐力不从心,影响视频业务体验质量。安徽联通引入“质差率”指标,针对端到端IPTV视频流丢包、时延长等问题,开展了IPTV网络架构、设备能力、网络容量和家庭组网等4个方面的研究,诊断出影响视频体验的网络问题,制定了网络优化方案,并提出开展家庭组网服务的建议,对提升IPTV用户业务感知、推动通信网络业务转型具有借鉴意义。

Analysis and Optimum Design of Differential Inductors Using Distributed Capacitance Model

A distributed capacitance model for monolithic inductors is developed to predict the equivalently parasitical capacitances of the inductor.The ratio of the self-resonant frequency (f SR) of the differential-driven symmetric inductor to the f SR of the single-ended driven inductor is firstly predicted and explained.Compared with a single-ended configuration,experimental data demonstrate that the differential inductor offers a 127% greater maximum quality factor and a broader range of operating frequencies.Two differential inductors with low parasitical capacitance are developed and validated.

Comparison of Mode Quality Factors for Equilateral Triangular, Square and Rhombus Optical Micro-Resonators

The mode frequencies and the quality factors for the equilateral triangular resonator (ETR), the square resonator (SR) and the rhombus resonator (RR) are numerically calculated by the finite difference time domain technique and the Padé approximation. The numerical results show that the resonant modes confined in an equilateral triangular cavity have much higher quality factors than those in the square or the rhombus cavities. The modes in the ETR are totally confined in transverse direction while those in the SR and RR are only partly confined. For the ETR with the side length of 4μm and the refractive index of 3 2, the mode quality factor of about 5 5×10 3 at the wavelength of 1 55μm has been obtained.

Chemical characterization and sources of PM2.5 at 12-h resolution in Guiyang, China

The increasing emission of primary and gaseous precursors of secondarily formed atmospheric particulate matter due to continuing industrial development and urbanization are leading to an increased public awareness of environmental issues and human health risks in China. As part of a pilot study, 12-h integrated fine fraction particulate matter （PM2.5） filter samples were collected to chemically characterize and investigate the sources of ambient particulate matter in Guiyang City, Guizhou Province, southwestern China. Results showed that the 12-h integrated PM2.5 concentrations exhibited a daytime average of 51 ± 22 μg m^-3 （mean -4- standard deviation） with a range of 17-128 μg m^-3 and a nighttime average of 55 ± 32 μg m^-3 with a range of 4-186 μg m^-3. The 24-h integrated PM2.5 concentrations varied from 15 to 157 μg m^-3, with amean value of 53 ± 25 μg m^-3, which exceeded the 24-h PM2.5 standard of 35μg m^-3 set by USEPA, but was below the standard of 75 μg m^-3, set by China Ministry of Environmental Protection. Energy-dispersive X-ray fluorescence spectrometry （XRF） was applied to determine PM2.5 chemical element concentrations. The order of concentrations of heavy metals in PM2.5 were iron （Fe） 〉 zinc （Zn） 〉 manganese （Mn） 〉 lead （Pb） 〉 arsenic （As）〉 chromium （Cr）. The total concentration of 18 chemical elements was 13 ± 2 μg m^-3, accounting for 25% in PM2.5, which is comparable to other major cities in China, but much higher than cities outside of China.

Ionic Conduction and Fuel Cell Performance of Ba0.97Ce0.8Ho0.2O3-α Ceramic

The perovskite-type-oxide solid solution Ba0.97Ce0.8Ho0.2O3-α was prepared by high temperature solidstate reaction and its single-phase character was confirmed by X-ray diffraction. The ionic conduction of the sample was investigated using electrical methods at elevated temperatures, and the performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured, which were compared with those of BaCe0.8Ho0.2O3-α. In wet hydrogen, BaCe0.8Ho0.2O3-α almost exhibits pure protonic conduction at 600-1000℃, and its protonic transport number is 1 at 600-900 ℃ and 0.99 at 1000 ℃. Similarly, Ba0.97Ce9.8Ho0.2O3-α exhibits pure protonic conduction with the protonic transport number of 1 at 600- 700℃, but its protonic conduction is slightly lower than that of BaCe0.8Ho0.2O3-α, and the protonic transport number are 0.99-0.96 at 800-1000 ℃. In wet air, the two samples both show low protonic and oxide ionic conduction. For Ba0.97Ce0.8Ho0.2O3-α, the protonic and oxide ionic transport numbers are 0.01-0.11 and 0.30-0.31 respectively, and for BaCe0.8Ho0.2O3-α, 0.01-0.09 and 0.27-0.33 respectively. Ionic conductivities of Ba0.97Ce0.8Ho0.2O3-α are higher than those of BaCe0.8Ho0.2O3-α under wet hydrogen and wet air. The performance of the fuel cell using Ba0.97Ce0.8Ho0.2O3-α as solid electrolyte is better than that of BaCe0.8Ho0.2O3-α. At 1000 ℃, its maximum short-circuit current density and power output density are 465 mA/cm^2 and 112 mW/cm^2, respectively.

Production and Nutritive Value of Calopo with Nitrogen and Phosphorus Fertilizer from Difference Sources

Calopogonium mucunoides （calopo） is one of forage legumes as protein and mineral sources for ruminant livestock in the tropics. However, most of the land in Indonesia that used for forage crops production characterized by acid pH, low in nitrogen and phosphorus. Phosphorus fertilizers have been used widely to improve soil fertility in Indonesia. As the high cost of superphosphate （SP）, the focus is now on rock phosphate （RP） fertilizer which relatively cheaper than SP, and it has high solubility in acid condition. Combination between nitrogen and phosphorus fertilizer from difference sources may be a promising technique to overcome those problems. A field experiment was conducted on a latosolic soil （low pH, nitrogen and low available Bray II extractable P）. The objective of the research is to evaluate the effect of combination between nitrogen and phosphorus fertilizer from difference sources on dry matter production and digestibility, nitrogen and phosphorus uptake of Calopogonium mucunoides （calopo）. Completely randomized block design with 9 treatments in 3 replicates was used in this experiment. The treatments were TO （control）, TI （SP）, T2 （RP）, T3 （urea）, T4 （ZA）, T5 （SP ＋ urea）, T6 （SP ＋ ZA）, T7 （RP ＋ urea）, T8 （RP ＋ ZA）. Size of plot was 2 m × 3 m, fertilized with 50 kg N/ha and 200 kg P2O5/ha, according to the assigned treatment. All plot received basal fertilizer of KCI （100 kg KzO/ha） and goat manure （5 ton/ha）. Calopogonium mucunoides was defoliated and nutritive value. Result showed that dry matter production on 90 days after planting and analyzed for dry matter production and nutritive value significantly influenzed by the treatments. Combination between N （ZA, urea） and P （SP, RP） fertilizer resulted dry matter production, nutrient uptake, and dry matter digestibility significantly higher compared to control, and NP fertilization separatedly. Combination of RP and N （urea, ZA） resulted in dry matter production, nutrient uptake, and dry matter digestibility non-significantly different compared to SP in combination with N （urea, ZA）. Therefore, RP could replace SP if combined with urea or ZA to increase production and nutritive value of Calopogonium mucunoides in acid latosolic soil.

Preparation and Characterization of TiO_2/Expanded Graphite

In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high tempera- ture. The samples were analysed by using scanning electron microscope （SEM）, X-ray diffraction（XRD）, energy disperse spectroscopy （EDS）, and differential scanning calorimetry （DSC）. The optimal conditions for preparation are as follows： the molar ratio of tetrabutyl orthotitanate to triethanolamine is 1 ： 0.4, and the calcination and expansion temperature is in the range of 650--750 ~C. Under such conditions, the expansion volume of composites could reach 98 mE/g, and the mass loss ratio is less than 5%. The analysis shows that lower temperature and smaller particle size of graphite are helpful to the formation of anatase-type of TiO2, but larger particle size will lead to lower mass loss ratio, and higher temperature and larger particle size will lead to higher expansion volume.