计算机优化饲料配方软件的研制

目前国内几个不同版本的饲料配方饮件主要采用线性规划和目标规划进行配方优化设计。采用这两种方法进行优化调剂时,往往不能一次得到满意的结果,须经过多次调整。模糊经性规划能根据各项营养成分的影子价格自动按用户给出的伸缩量调整配方,且能得到一个较理想的结果。这是模糊线性规划优于其它方法的主要特征。开发了用模糊线性规划优化料配方设计的软件,介绍了该软件的总体设计及系统的各功能模块。     

几种规划在优化饲料配方设计中的比较

通过实例分析,探讨了线性规划,目标规划和模糊线性规划三种优化技术在饲料配方设计中的应用,客观地对它们之间的联系,区别和优缺点进行了比较。．     

应用分组编码调制的超宽带自相关接收机及其性能分析

由于实现简单,非相干传输参考接收机(TR)对于超宽带通信具有较大吸引力,但另一方面,由于需要发送参考脉冲,降低了系统的能量效率和数据传输率.为克服这一缺点,现有文献提出一种采用分组编码调制方案的码字匹配与信号汇聚(CMSA)接收机,但相关文献没有对 CMSA 接收机的最优性和误码性能进行理论分析.针对这一问题,本文基于广义最大似然比检验,提出一种针对分组编码调制超宽带信号的新型非相干接收机.该接收机与 CMSA 接收机的码字判决规则等价,即证明了 CMSA 接收机实质上是广义最大似然意义下的最优接收机.与 CMSA 接收机不同,新型接收机采用脉冲帧信号进行自相关的结构,具有实现更加简单和灵活的特点.同时文中对接收机的错误性能进行了理论分析,在推导成对差错概率的基础上得到接收机的误比特率理论上界,多径衰落信道下的仿真结果表明当误比特率小于 10-3 时,该理论上界是误比特率的一个很好近似.     

三峡工程基础帷幕灌浆试验

根据三峡工程坝基岩石地质特点,采用“孔口封闭、高压灌浆”法和ＧＩＮ法以及使用没灌浆材料,在现场进行灌浆试验,以便对三峡工程主体建筑物基础灌浆设计技术参数进行验证并寻求合适的交流 材料、施工方法与工艺措施。此次帷幕灌浆试验结果表明：“孔口封闭、高压灌浆”法灌浆效果明显,能达到设计源防渗标准;ＧＩＮ灌浆法,其抗生及耐久性达不到设计要求。湿磨普通水泥浆液和改性灌浆水泥,均能满足三峡帷幕灌浆对浆材的要求。     

子载波间隔自适应OFDM系统研究

随着无线电技术的发展,对正交频分复用系统的频谱效率要求越来越高,子载波间隔是影响系统频谱效率的主要因素.本文推导出了时变频率选择性信道下OFDM系统容量表达式,然后分析了子载波间隔对OFDM系统频谱效率的影响,提出了子载波间隔自适应以最大化频谱效率的方法,仿真结果证明此类自适应技术能大幅提高OFDM系统的频谱效率.     

Study and formation of 2D microstructures of sapphire by focused ion beam milling

Dry etching of C-plane sapphire wafer has been studied using Ga⁺ focused ion beam milling (FIBM). Due to a much lower milling rate of sapphire compared to GaN, it has been proven that gas-assisted FIBM (GAFIBM) is a necessity. Furthermore, it needs to be determined whether XeF₂- or I₂-GAFIBM can improve the technique. We found that XeF₂-GAFIBM gave the highest milling rate. The obtained enhancement factor of the XeF₂-GAFIBM milling rate compared to FIBM rate varied from 2.3 to 1.2 for the ion beam current in the range 20 pA-1 nA. A favorable milling rate selectivity of sapphire to nickel film of about 1.5 was obtained by XeF₂-GAFIBM at 350 pA. We have successfully fabricated a variety of 2D sapphire-based submicron pillar or hole arrays in regular crystals, quasicrystals and aperiodic symmetries. The nearest neighbor distance was down to 230 nm. The depth achieved was deeper than 400 nm. The air filling factor ranged from 12% to 60%. These sapphire-based 2D microstructures were applied on flip-chip GaN-based light emitting diodes (LEDs) and more than 40% improvement in light extraction was obtained.     

“网河”非稳定流模型在洪泛区洪流演进中的应用

将宽阔的溃口洪水行进范围概化成由河道水塘和联系河道组成的网河,用一维非恒定流方程组来描述主要的水充运动状态,通过简化和变换,改写成统一的四点线性隐式有限差的方程组形式,再用双消除法求解,全部计算在微机上实现,参数用实测资料率定,成果具有较好的精度,在一定程度上反映出横水流方向的水位流量变化,为防洪水利计算开辟一条新的途径。     

Design issues of optical IP routers for Internet backboneapplications

The rapid increase of Internet traffic is pushing the deployment of WDM technology in the next-generation high-speed Internet backbone. Routers in the backbone could still be the potential bottleneck. In this article we consider some design issues of high-throughput optical routers which combine the advantages of WDM with the new optical switching technology. We first introduce a proposed Internet architecture based on the optical burst switching mechanism. Some important design issues in optical buffering and control function are addressed which are expected to have significant effects on router performance. Numerical results of a simulation study are also presented along with discussions     

Magnetoconductance of polymer–fullerene bulk heterojunction solar cells

The organic magnetoconductance (MC) effects in poly(3-hexylthiophene): [6,6]-phenyl-C61-butyricacid methylester based bulk heterojunction solar cells were studied in dark and under illumination. The correlations between the MC and current character were revealed in this study. Results show that the dark current always exhibits a negative MC whereas a sign change in MC under illumination occurs at the bias around the open circuit voltage V_oc. We suggest that the positive MC in photocurrent is due to the field dependent conversion of singlet electron–hole pairs to triplet states and the negative MC is associated with space charge limited current with traps. Other possible mechanisms about the magnetoconductance effects are also discussed.     

Control architecture in optical burst-switched WDM networks

Optical burst switching (OBS) is a promising solution for building terabit optical routers and realizing IP over WDM. In this paper, we describe the basic concept of OBS and present a general architecture of optical core routers and electronic edge routers in the OBS network. The key design issues related to the OBS are also discussed, namely, burst assembly (burstification), channel scheduling, burst offset-time management, and some dimensioning rules. A nonperiodic time-interval burst assembly mechanism is described. A class of data channel scheduling algorithms with void filling is proposed for optical routers using a fiber delay line buffer. The LAUC-VF (latest available unused channel with void filling) channel scheduling algorithm is studied in detail. Initial results on the burst traffic characteristics and on the performance of optical routers in the OBS network with self-similar traffic as inputs are reported in the paper.