A noise constrained least mean fourth (NCLMF) adaptive algorithm

The learning speed of an adaptive algorithm can be improved by properly constraining the cost function of the adaptive algorithm. In this work, a noise-constrained least mean fourth (NCLMF) adaptive algorithm is proposed. The NCLMF algorithm is obtained by constraining the cost function of the standard LMF algorithm to the fourth-order moment of the additive noise. The NCLMF algorithm can be seen as a variable step-size LMF algorithm. The main aim of this work is to derive the NCLMF adaptive algorithm, analyze its convergence behavior, and assess its performance in different noise environments. Furthermore, the analysis of the proposed NCLMF algorithm is carried out using the concept of energy conservation. Finally, a number of simulation results are carried out to corroborate the theoretical findings, and as expected, improved performance is obtained through the use of this technique over the traditional LMF algorithm.     

混凝土植筋锚固

混凝土结构植筋锚固的使用受多种因素制约,植筋锚固材料的耐久性、稳定性、耐火性、使用部位、钢筋锚固长度、锚固区混凝土的约束等在设计时都应慎重考虑。     

Risk-constrained self-scheduling of a fuel and emission constrained power producer using rolling window procedure

This work addresses a relevant methodology for self-scheduling of a price-taker fuel and emission constrained power producer in day-ahead correlated energy, spinning reserve and fuel markets to achieve a trade-off between the expected profit and the risk versus different risk levels based on Markowitz’s seminal work in the area of portfolio selection. Here, a set of uncertainties including price forecasting errors and available fuel uncertainty are considered. The latter uncertainty arises because of uncertainties in being called for reserve deployment in the spinning reserve market and availability of power plant. To tackle the price forecasting errors, variances of energy, spinning reserve and fuel prices along with their covariances which are due to markets correlation are taken into account using relevant historical data. In order to tackle available fuel uncertainty, a framework for self-scheduling referred to as rolling window is proposed. This risk-constrained self-scheduling framework is therefore formulated and solved as a mixed-integer non-linear programming problem. Furthermore, numerical results for a case study are discussed.     

Daily integrated generation scheduling for thermal,pumped‐storage,and cascaded hydro units and purchasing power considering network constraints

We have developed an innovative power generation scheduling method using quadratic programming (QP). The advantage of using our method is that it simultaneously solves unit commitment and economic load dispatch. We relax the binary variables of the unit state into continuous variables to apply QP to this problem. We also add a penalty term to converge the value of those variables to 0 or 1 to the objective function: the sum of the fuel costs and the start‐up costs. This penalty term depends on the per‐unit fuel cost. The possibility of its variable converging to zero increases as the cost increases. This method was applied to a test system of daily generation scheduling that consisted of 29 thermal units, two pumped‐storage units, four cascaded hydro units, and one transmission. The schedule satisfied all constraints, that is, load‐power balance, operation reserve, power flow, minimum up/down‐times, and fuel consumption. This result shows that the proposed method is effective. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 25–34, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21014     

基于稠密局部自相似特征流的图像配准算法

针对基于稠密SIFT流图像配准算法执行效率和配准准确率有待提高的不足,提出了一 种基于稠密局部自 相似(LSS)描述符构建的稠密改进的LSS(ILSS)特征流的图像配准算法。算法通过颜色空间转 换分离出彩色图像中的 颜色和亮度信息,只在亮度通道上提取稠密LSS特征以大幅度提高图像特征提取阶段 执行效率。随后以 保持特征流场光滑性为约束条件,采用金字塔多分辨率迭代法提高LSS特征流场估计 阶段的执行效率。 多分辨率迭代法的基本思想是先在图像粗粒度网格上快速估算出初步的特征流场,然后再逐 步求精获得最 终精确的特征流场。大量实验表明,与稠密SIFT流相比,基于稠密ILSS特征流的图像 配准算法在图像内容发生较大变化时具有更好的鲁棒性,同时具有更高的执行效率和图像配 准确率。     

A pumping lemma for random permitting context languages

Random context grammars belong to the class of context-free grammars with regulated rewriting. Their productions depend on context that may be randomly distributed in a sentential form. Context is classified as either permitting or forbidding, where permitting context enables the application of a production and forbidding context inhibits it. For random context languages of finite index a generalization of the well-known pumping lemma for context-free languages has been proven. We drop the finite index restriction and concentrate on non-erasing grammars that use permitting context only. We prove a pumping lemma for their languages that generalizes and refines the existing one, and show that these grammars are strictly weaker than the non-erasing random context grammars.     

嵌入式控制状态转移的确定性实时语义义

嵌入式控制是在实时事件驱动下物理系统状态转移的执行过程, 采用超致密时间(SDT) 标签表示事件的实时性, 描述一种自然表达时间的实时状态转移语义模型; 证明事件实时标签是时间值上的偏序函数, 实时事件的状态转移顺序与对应的非实时过程一样; 针对状态转移轨迹中的实时约束条件, 把非实时过程上的操作扩展到实时过程, 得到确定性的操作执行顺序. 一个控制横毛织机编织运动的实例表明了语义表达的有效性.     

Socio-economic hurdles to widespread adoption of small-scale biogas digesters in Sub-Saharan Africa: A review

The unsustainable use of fossil fuels has led to increased awareness and widespread research on the accessibility of renewable energy resources such as biogas. Biogas is a methane rich gas that is produced by anaerobic fermentation of organic material. Despite its potential to replace biomass in Africa, where over 70% of the households use wood fuel and agricultural waste for cooking, biogas technology has not been adopted by Sub-Saharan African countries compared to their Asian counterparts. This paper examines the socioeconomic constraints to adoption of biogas in Sub-Saharan Africa and explores factors that could enhance adoption of the technology. These include standardization and quality control, as well as an approach of integrated farming using biogas and slurry. The article recommends mobilization of local and external funds to promote biogas, use of ready to use funds such as the Clean Development Mechanisms in overcoming the initial construction costs of biogas units, and formation of user and disseminator associations to reduce costs by joint procurement and linkage to finance. It further advocates the promotion of multiple uses of biogas for purposes other than cooking and lighting. It is expected that widespread adoption of the technology could lead to self-sufficiency in household energy provision for cooking. This would facilitate environmental management and economic development in Sub-Saharan Africa.     

拉格朗日乘数法求解约束线性回归问题研究

参数满足特定线性等式约束的最小二乘估计问题是在各种各样的应用问题中产生的。为了求解带有多个约束条件的多元线性回归的参数估计问题,基于广义逆矩阵理论,利用多元微积分求条件极值的拉格朗日乘数法,通过建立辅助函数,把带有多个约束条件的多元线性回归参数估计问题转化为计算无条件极值,并给出了矩阵解法的计算公式。     

Organisational routines in multi-project contexts: Coordinating in an urban development project ecology

Project management literature have focused on either intra-organisational relationships or on vertical inter-organisational relationships. The purpose of this paper is to explore inter-project interdependencies and coordinating in multi-project contexts by using the notion of project ecologies. We adopt an organisational routines perspective to explore the coordinating practices managing those interdependencies. The empirical material underpinning our findings were collected and analysed through a case study of an urban development district, new to both the project ecology literature and the organisational routines literature. The findings highlight the existence and importance of horizontal interdependencies in project ecologies, as compared to the more commonly studied interdependencies in vertical relationships within and between projects. The need for horizontal coordinating is outside project managers’ regular focus on steering vertical relationships. Accordingly, the routines to manage the horizontal interdependencies in project ecologies are different to those in more engineered routines that are often described in project management guidelines.