电信运营企业综合竞争力比较研究——中国联通视角评价分析

经济全球化以及世界信息产业的持续增长决定了电信市场正走向全球竞争.本文基于竞争力相关理论,采用定性与定量分析相结合,围绕财务运作能力、客户发掘能力、资源利用能力、企业成长能力等4个维度,利用3层架构建立30个具体指标来衡量电信运营企业竞争力水平.相互比较中研究中国联通与国内外著名电信运营企业的经营状况.探讨中国联通竞争力提高途径和策略,为电信运营企业管理实践提供了有效的操作思路.     

突发业务流的TES建模方法

高速通信网络存在大量诸如可变速率(VBR)视频这类具有突发性的业务流。突发性,在数学上主要通过业务流的到达时间间隔的边缘概率分布和自相关函数来描述。TES(Transform-Expand-Sample)是一种建模静态随机过程的非参数化技术,能准确匹配边缘概率分布并很好地近似自相关函数。本文简要介绍了TES方法的基本原理,再详细讨论突发业务流的TES建模及其软件实现。对MPEG视频业务的建模的仿真结果表明,TES模型能够很好地表征网络业务流的突发性。     

CDPD技术实验系统的研制

本文介绍了CDPD系统的网络体系结构,围绕空中接口,提出了CDPD实验系统的软硬件实现方案,给出了我们研制的CDPD系统的试验结果,并对结果进行了分析。     

激光微束穿刺法获得抗虫转基因油菜及其后代的研究

利用激光微束穿刺法将苏云金芽孢杆菌的毒蛋白 (δ endotoxin)基因导入了油菜 ,经聚合酶催化链式反应(PCR)和PCRSouthern杂交证明抗虫基因已导入油菜基因组中并能在T1 代得到遗传。对转基因植株进行了抗虫性测试 ,结果表明某些植株具有较好的抗虫性 ,并且这种抗虫性在T1 代仍能保持。实验结果表明抗虫基因已整合进油菜基因组并得到了稳定的遗传。     

Performance enhancement in organic photovoltaic devices using plasma-polymerized fluorocarbon-modified Ag nanoparticles

In this work, Ag nanoparticles were modified by an ultra-thin plasma-polymerized fluorocarbon film (CF_X) to form a composite CF_X-modified Ag nanoparticles/indium tin oxide (ITO) anode for application in organic photovoltaic (OPV) devices. A CF_X-modified Ag nanoparticles/ITO anode exhibited a superior surface work function of 5.4 eV suited for application in OPV devices. The performance of zinc phthalocyanine:fullerene-based OPV devices showed a significant improvement when the structural identical cells are made with the CF_X-modified Ag nanoparticles/ITO. This work yielded a promising power conversion efficiency of 3.5 ± 0.1%, notably higher than that with a bare ITO anode (2.7 ± 0.1%).     

Organic Tribotronic Transistor for Contact‐Electrification‐Gated Light‐Emitting Diode

Tribotronics is a new field about the devices fabricated using the electrostatic potential created by contact electrification as a “gate” voltage to tune/control charge carrier transport in semiconductors. In this paper, an organic tribotronic transistor is proposed by coupling an organic thin film transistor (OTFT) and a triboelectric nanogenerator (TENG) in vertical contact‐separation mode. Instead of using the traditional gate voltage for controlling, the charge carrier transportation in the OTFT can be modulated by the contact‐induced electrostatic potential of the TENG. By further coupling with an organic light‐emitting diode, a contact‐electrification‐gated light‐emitting diode (CG‐LED) is fabricated, in which the operating current and light‐emission intensity can be tuned/controlled by an external force–induced contact electrification. Two different modes of the CG‐LED have been demonstrated and the brightness can be decreased and increased by the applied physical contact, respectively. Different from the conventional organic light‐emitting transistor controlled by an electrical signal, the CG‐LED has realized the direct interaction between the external environment/stimuli and the electroluminescence device. By introducing optoelectronics into tribotronics, the CG‐LED has open up a new field of tribophototronics with many potential applications in interactive display, mechanical imaging, micro‐opto‐electro‐mechanical systems, and flexible/touch optoelectronics.     

Inserting a Mn-doped TiO2 layer for improving performance of pentacene organic thin-film transistors

Device performance of pentacene organic thin-film transistors (OTFTs) was significantly improved via inserting a Mn-doped TiO₂ layer between pentacene semiconductor and the source–drain electrodes. In comparison with the OTFTs with only-Au electrodes, the introduction of a thin Mn-doped TiO₂ layer leads to saturation current increasing from 31.9 μA to 0.22 mA, effective field-effect mobility improving from 0.24 to 1.13 cm²/V s, and threshold voltage downshifting from −11 to −2 V. These performance enhancements are ascribed to the significant reduction of contact resistance and smoothed surface of pentacene layer. This work may provide an effective approach to improve the performance of the pentacene based OTFTs by inserting a Mn-doped TiO₂ layer.     

Radio Resource Allocation in Multi-User Cooperative Relaying Networks with Resource Block Pairing and Fairness Constraints

In this paper we address the problem of radio resource allocation in cooperative relaying networks. We focus on the resource block and power allocations for the downlink of OFDM-based relaying multi-user network. The resource allocation is investigated for both amplify and forward and decode and forward protocols under the constraints of power, resource block pairing and data rate fairness. To reduce complexity, the optimization problem is solved in two steps. In the first step, resource block pairing and allocation are conducted jointly with equal transmission power for both the base station and the relay. In the second step, transmission power is further optimized to maximize the system throughput. Our analysis is focused on the total achievable system throughput and the achievable individual throughput for each user.     

CO-OFDM系统中利用阈值功率点改进的后向传输补偿算法

采用后向传输(BP)补偿算法补偿相干光正交频分复用(CO-OFDM)通信系统的非线性损伤是一种具有应用前景的方法。本文针对后向传输(BP)补偿算法计算复杂度高的问题,根据相干光正交频分复用(CO-OFDM)系统中非线性损伤与光功率的关系,通过选取合适的阈值功率点降低BP补偿算法的高计算复杂度。仿真结果表明,提出的方法可以大大降低BP补偿算法的计算复杂度,同时克服了传统算法过补偿的缺点,系统性能也得到提升。在100Gbit/s的CO-OFDM系统中,采用衰减因子为0.2dB/km的零色散光纤,信号传输3 200km(32×100km),光信噪比(OSNR)为16dB时,在选取合适的阈值功率点后,所需的BP补偿步骤数目由传统算法N=61降低为N=13,计算复杂度仅为原来的13/61。此外,采用改进的BP补偿算法补偿之后,系统的Q因子增加了0.204dB。