Design of power control mechanisms with PCM realization for theuplink of a DS-CDMA cellular mobile radio system

Power control (PC) is an important issue in a direct sequence-code division multiple access (DS-CDMA) cellular mobile radio system. Higher link performance and greater system capacity cannot be achieved unless an appropriate PC mechanism is employed. In previous research, a delta-modulation (DM) realization of strength-based and SIR-based PC mechanisms for uplink communication has been studied by simulation. In order to obtain higher PC trackability, we study a pulse-code-modulation (PCM) realization of the above two PC mechanisms for the uplink of a DS-CDMA cellular mobile radio system. The simulation results presented indicate that the PC mechanisms with PCM realization for the uplink can achieve a lower outage probability and thus higher link performance than the PC mechanisms with DM realization. We also obtain optimal design parameters such as the stepsize and the control mode for the two PCM PC mechanisms. In addition, we compare the two PCM PC mechanisms in terms of their outage probability and stability and find that the strength-based mechanism has a higher outage probability but greater stability than the SIR-based mechanism     

混合比对市政污泥与餐厨垃圾二级高温共消化的影响

研究不同混合比下市政污泥与餐厨垃圾二级高温共消化的情况。实验分别采用污泥与餐厨TS之比为3∶1,4∶1,5∶1的3种混合比,主要考查了混合比对二级反应罐的影响。研究表明,不同的混合比对各反应罐达到稳定时出料的COD浓度、VS的含量及其去除率、日产气量以及产气中甲烷含量等都有一定的影响,混合比为3∶1,4∶1,5∶1的反应罐稳定时出料的COD浓度分别为13 500,10 000,23 000mg/L,混合比为4∶1时,出料COD浓度最低。稳定时VS的含量随着混合比的增加而升高,分别为0.034 7,0.039 6,0.045 6g/g物料,VS的去除率分别为42.8%,26.7%,5.2%;稳定时各反应罐的日产气量随着混合比的升高而降低,分别为12 000,5 500,4 500mL,产气中甲烷含量分别为92.49%,91.55%,88.69%。     

零散天然气化工利用研究

根据零散天然气分散而且量较小的特点对其化工利用的途径进行探讨,提出撬装一步生产尿素、撬装生产甲醇和生产合成油等化工利用途径,并对其技术经济性能进行了估算。     

Olefins from conventional and heavy feedstocks: Energy use in steam cracking and alternative processes

Steam cracking for the production of light olefins, such as ethylene and propylene, is the single most energy-consuming process in the chemical industry. This paper reviews conventional steam cracking and innovative olefin technologies in terms of energy efficiency. It is found that the pyrolysis section of a naphtha steam cracker alone consumes approximately 65% of the total process energy and approximately 75% of the total exergy loss. A family portrait of olefin technologies by feedstocks is drawn to search for alternatives. An overview of state-of-the-art naphtha cracking technologies shows that approximately 20% savings on the current average process energy use are possible. Advanced naphtha cracking technologies in the pyrolysis section, such as advanced coil and furnace materials, could together lead to up to approximately 20% savings on the process energy use by state-of-the-art technologies. Improvements in the compression and separation sections could together lead to up to approximately 15% savings. Alternative processes, i.e. catalytic olefin technologies, can save up to approximately 20%.     

电力范围远期合同的定价分析及仿真研究

为规避市场风险,电力远期合同受到了广泛关注。借鉴金融外汇市场上常见的范围远期合同,提出一种新的电力双边范围远期合同,以期减少买卖电双方的交易风险、稳定市场。与普通差价合同相比,范围远期合同更具实用性,为交易双方提供了一个电价估计的区间,即把价格从一点扩展为一个范围,并得到了此区间上下限独立的方程,证明了方程解的存在性。通过算例仿真和理论研究,范围远期合同更具避风险能力,更能提高远期合同市场的运作效率。     

太阳电池内部电阻对其输出特性影响的仿真

通过对太阳电池的等效电路进行分析,建立了太阳电池的计算机仿真模型,定量地模拟了在一定光照下太阳电池内部的等效并联电阻及串联电阻对其伏安特性、开路电压、短路电流及填充因子的影响的程度。仿真结果表明：等效并联电阻产生的漏电流会影响太阳电池的反向特性和正向小偏压特性,且并联电阻影响其开路电压,但对短路电流基本没有影响；等效串联电阻会影响太阳电池的正向伏安特性和短路电流,而对开路电压没有影响；另外,并联电阻的减小和串联电阻的增大都会使太阳电池的填充因子和光电转换效率降低。仿真结果与实际测量的数据取得了相一致的结论。     

基于宽带隙P-I-N结构的高效有机小分子太阳电池

研制了一种采用混合的P-I-N异质结结构、基于混合ZnPc和C60的有机小分子太阳电池。该有机太阳电池光电转换由ZnPc和C60异质结混合成膜完成,电子和空穴分别通过n掺杂和p掺杂的宽带有机层传输至阴极和阳极,不同掺杂的电子或空穴传输层由精确控制两种有机小分子的蒸镀速率来实现;其中空穴传输层采用N,N,N’,N-’Tetrakis(4-methoxyphenyl)-benzidine(MeO-TPD)为基底材料和Tetrafluoro-tetracyano-quinodimethane(F4-TCNQ)为掺杂材料,电子传输层采用C60为基底材料,而掺杂材料为Leuco Crystal violet(LCV)。实验发现:可以通过改变光电转换层和电子传输层的厚度,优化器件的结构;与未掺杂的有机薄膜相比,掺杂的宽带有机传输层导电率提高了3~4个数量级,并且它们几乎不吸收太阳光;电子传输层的厚度直接影响太阳电池的转换效率,这与薄膜光学的预期结果相符;当增大光电转换层的厚度,不仅增加了光吸收,同时电子空穴的复合率也随之增加,因此器件的填充因子降低。实验结果表明:该有机太阳电池的光电转换效率可达2.4%。     

轴承式摇臂在摩托车上的应用

介绍了一种新型轴承式摇臂在摩托车上的应用，以其取代常用的整体式普通摇臂，经过试验表明，这种新型摇臂能够有效地提高发动机的中低速扭矩。     

摩托车点火系统初级回路参数的优化在高能点火中的应用

本文分析了摩托车点火系统的初级回路，给出了初级能量与初级回路的各种参数的关系式，为精确控制点火能量及其可靠性提供了理论依据。     

柴油机轴瓦损伤的故障分析

针对柴油机在工作中常见的轴瓦故障现象及特征,阐述了轴瓦损伤故障判断与检查的方法,分析了造成这些轴瓦损伤的原因,最后对避免出现类似故障提出了几点安装和维护的对策。