小回线装置TEM法在病害地质勘察中的应用

小回线装置瞬变电磁法(TEM)具有地形影响小、施工效率高等优势,在地质勘察工作中得到了广泛的应用。引入小回线装置TEM法对病害地质进行勘察,能有效地避免岩溶、滑坡、沉降、崩塌等地质灾害,提升建筑物的稳定性,减少对社会和人们的生命财产安全的危害。     

加性白噪声下基带延迟锁定环跟踪精度的计算

研究了加性白噪声下基带延迟锁定环跟踪精度的计算问题,着重讨论了积分时间和 环路带宽的关系。以码延迟相关鉴别器的等效鉴相模型为基础,研究了相关器输出噪声特性 及其在输入端等效噪声的特性,推导了线性跟踪环输出噪声方差的计算公式,并得到了积分 时间和环路带宽分别起主导作用时的简化计算公式,使两种不同的结论得到了统一。     

Designing a reverse logistics network for optimal collection, recovery and quality-based product-mix planning

This study proposes an integrated, reverse logistics supply chain planning process with modular product design that produces and markets products at different quality levels. A mixed integer programming (MIP) model formulates the overall planning process required to maximize profit by considering the collection of returned products, the recovery of modules and the proportion of the product mix at different quality levels. This paper proposes the collection of returnables (end-of life, defective, product under warranty) through retail outlets combined with the recovery of modules from the collected products using a network of recovery service providers. The proposed modular product design approach would create a design criterion that provides an improved recovery process at a lower cost. This study uses a total supply chain view that considers the production, transportation and distribution of products to customers, while a numerical problem illustrates the applicability of the models.     

黄河下游治理方略演变及综合治理前沿技术

较为全面地回顾了我国黄河下游治理方略的演变,着重介绍了黄河下游治理的最新科研成果——流域"分区治理"新方略.新方略将黄河河道至大堤之间的流域空间依次划分为生态移民安置区、高效生态农业区和生态湿地等功能区,利用泥沙放淤、挖河疏浚等技术手段实施滩区再造,建设嫩滩、二滩和高滩,以达成洪水分级设防、泥沙分区落淤、滩槽水沙自由交...     

在负荷变化大的工况下轧机的智能控制

针对中国轧机控制技术较低的实际情况,提出了在闭环调速基础上应用模糊PID和模糊神经网络到轧机初轧控制系统中的方案,详细介绍了该控制系统优化算法的实现过程。此方案实现了对调节时间和超调量的双重优化,提高了轧机的抗扰性、启动时的平稳性,并减少了因超调引起的附加机械损耗,使轧制生产线自动化控制水平显著提高。     

自适应网络结构的故障行波定位方法

输电网中环路的存在会影响故障初始行波到达时间与行波传输路径的匹配,影响故障点位置的计算。为此,提出了一种自适应网络结构的故障行波定位方法。对于故障线路不包含于环路的情况,利用Floyd算法搜索故障点到网络中各节点的最短路径;对于故障线路包含于环路的情况,确定环路中初始行波到达时间最大的节点为解环点,并提出了剔除无效路径的时间判据,将复杂故障网络简化为辐射形网络。在辐射形网络中,运用基于整个电网的故障行波定位算法,实现全网综合定位。仿真结果表明,该方法实现简单,适用于任何结构的电网,能够有效弥补现有行波网络定位算法的缺陷和不足。     

生态河道种植圈对水流水力特性的影响

采用三维超声波多普勒测速仪对河道生态修复中种植圈布设前后的工况量测,比较了布设种植圈前后的流速分布、紊动强度和雷诺应力的变化．结果表明,布设种植圈后,纵向流速分布波动明显,相对紊动强度和雷诺应力均略有增加．     

Unbundling and infrastructure competition for broadband adoption: Implications for NGA regulation

The common idea of open access policy is that it refers to the sharing of particular elements, such as wholesale access networks, backhaul, under-sea cable and internet exchange points in fixed and mobile networks. In broadband networks, the use of open access policy usually refers to the infrastructure parts, which are considered a bottleneck. Many regulators have generally focused open access policy on fixed broadband networks, especially digital subscriber line (DSL) technology, in the last decade. Local loop unbundling (LLU) regulation is one of the main strategies for the regulator to open access to an incumbent’s bottleneck network in order to soften its monopoly power and encourage competition in the DSL broadband market. The OECD countries have different strategies regarding unbundling local loop and infrastructure competition, as the characteristics and infrastructure networks of countries vary. There are currently more choices of next generation network (NGN) technologies to develop. While local loop unbundling may not be applied fully to NGN development (the cost is not sunk, more technologies are available to implement, incentive of investment by operator), it can indicate benefits and drawbacks of open access policy in the past decade that can be adapted to NGN.The empirical results of this study show that during 2002–2008, LLU regulation was one of the strategies used to increase broadband adoption in countries that had difficulty encouraging infrastructure competition. Unbundling regulation can therefore be implemented carefully and differently in each country that has inefficiency that is harmful to consumers in its market from a monopoly incumbent. Infrastructure competition, on the other hand, is introduced as another strategy to increase broadband adoption. The empirical results of this study indicate that infrastructure competition can be used as a strategy when there are already enough infrastructures in the area or country. These results support the idea of using open access and infrastructure competition policy depending on the existing competition of broadband infrastructure in each country.     

大朝山水电站机组筒形阀控制回路故障分析及改造

大朝山水电站水轮机组采用筒形阀作为停机断流部件,但筒形阀控制回路在设计上存在不足,投产初期,筒形阀接力器下腔在开机后不能保持压力。为解决问题,短接了控制回路一对节点,却造成筒阀开启回路长期带电,加快了元件老化,多次出现故障,产生新的隐患。文章分析了筒形阀开启回路并提出改造建议。     

圆线圈及亥姆霍兹线圈的磁场分布

直接从毕奥-莎伐尔定律写出固线圈在空间任一点磁场分量的积分表达式．通过数值计算给出其分布曲线，进一步给出亥姆霍兹线圈的磁场分布曲线．非常直观。该文还讨论了探测线圈直径对测量精度的影响．并给出亥姆霍兹线圈的均匀磁场区的范围。