Revisiting CO2 emissions convergence in G18 countries

This study revisits whether CO₂ emissions converge in G18 countries over the period of 1950–2013. To work on this empirical analysis, we employ a more powerful quantile unit root test with per capita CO₂ emissions. While conventional unit root tests fail to reject convergence in CO₂ emissions in these G18 countries, quantile unit root test results demonstrate CO₂ emissions converged in 5 of these G18 countries (i.e., Australia, Brazil, Canada, Germany, and India). Our empirical results have important policy implications for the governments of G18 countries to direct efficient and effective energy policies to reduce the CO₂ emissions.     

非光滑凸问题投影型对偶平均优化方法的个体收敛性

对于一般凸问题,对偶平均方法的收敛性分析需要在对偶空间进行转换,难以得到个体收敛性结果.对此,文中首先给出对偶平均方法的简单收敛性分析,证明对偶平均方法具有与梯度下降法相同的最优个体收敛速率Ο(lnt/t).不同于梯度下降法,讨论2种典型的步长策略,验证对偶平均方法在个体收敛分析中具有步长策略灵活的特性.进一步,将个体收敛结果推广至随机形式,确保对偶平均方法可有效处理大规模机器学习问题.最后,在L1范数约束的hinge损失问题上验证理论分析的正确性.     

Multi-elite guide hybrid differential evolution with simulated annealing technique for dynamic economic emission dispatch

This paper proposes an improved multi-objective differential evolutionary algorithm named multi-objective hybrid differential evolution with simulated annealing technique (MOHDE-SAT) to solve dynamic economic emission dispatch (DEED) problem. The proposed MOHDE-SAT integrates the orthogonal initialization method into the differential evolution, which enlarges the population diversity at the beginning of population evolution. In addition, modified mutation operator and archive retention mechanisms are used to control convergence rate, and simulated annealing technique and entropy diversity method are utilized to adaptively monitor the population diversity as the evolution proceeds, which can properly avoid the premature convergence problem. Furthermore, the MOHDE-SAT is applied on the thermal system with a heuristic constraint handling method, and obtains more desirable results in comparison to those alternatives established recently. The obtained results also reveal that the proposed MOHDE-SAT can provide a viable way for solving DEED problems.     

Convergence analysis of the alternating RGLS algorithm for the identification of the reduced complexity Volterra model

In this paper we provide a convergence analysis of the alternating RGLS (Recursive Generalized Least Square) algorithm used for the identification of the reduced complexity Volterra model describing stochastic non-linear systems. The reduced Volterra model used is the 3rd order SVD-PARAFC-Volterra model provided using the Singular Value Decomposition (SVD) and the Parallel Factor (PARAFAC) tensor decomposition of the quadratic and the cubic kernels respectively of the classical Volterra model. The Alternating RGLS (ARGLS) algorithm consists on the execution of the classical RGLS algorithm in alternating way. The ARGLS convergence was proved using the Ordinary Differential Equation (ODE) method. It is noted that the algorithm convergence canno׳t be ensured when the disturbance acting on the system to be identified has specific features. The ARGLS algorithm is tested in simulations on a numerical example by satisfying the determined convergence conditions. To raise the elegies of the proposed algorithm, we proceed to its comparison with the classical Alternating Recursive Least Squares (ARLS) presented in the literature. The comparison has been built on a non-linear satellite channel and a benchmark system CSTR (Continuous Stirred Tank Reactor). Moreover the efficiency of the proposed identification approach is proved on an experimental Communicating Two Tank system (CTTS).     

Trajectories of knowledge economy in SSA and MENA countries

In the first critical assessment of knowledge economy dynamic paths in Africa and the Middle East, but for a few exceptions, we find overwhelming support for diminishing cross-country disparities in knowledge-based economy dimensions. The paper employs all the four components of the World Bank's Knowledge Economy Index (KEI): economic incentives, innovation, education, and information infrastructure. The main finding suggests that sub-Saharan African (SSA) and the Middle East and North African (MENA) countries with low levels of KE dynamics and catching-up their counterparts of higher KE levels. We provide the speeds of integration and time necessary to achieve full (100%) integration. Policy implications are also discussed.     

尖山铁矿破碎机硐室收敛速率与暴露面积的相关分析

在尖山铁矿破碎机硐室施工过程中对围岩的暴露面积和收敛速率间相关性进行了分析，并对硐室拱顶收敛速率与暴露面积关系进行了回归分析、给出了表达式，指出了尖山铁矿破碎机硐室施工过程中的空顶距、分层高度等参数。     

矿井噪声主动控制技术研究及参数优化

矿井下有很多主动降噪设备降低噪声,但主要对高频噪声有较好的效果。针对井下环境中的复杂噪声信号,采用主动降噪算法降低噪声对矿工身心健康的影响,分析了LMS算法存在的次级声源信号的反馈和声音信号传输的延迟两大问题;针对存在的两大问题,采用FX-LMS算法,在次级通道上引入一传递函数对原始参考信号进行预处理,并给出了FX-LMS算法中收敛步长取值范围的求解方法,为寻求最优实验参数提供了参考依据。在MATLAB开发环境中,对混有白噪声的声音信号进行降噪处理,给出了不同收敛步长下的仿真结果,结果表明FX-LMS算法是有效的,并验证了收敛步长会影响收敛速度和稳态误差。     

破碎难采矿体开采地压的测试研究

针对新城金矿极破碎顶底柱难以安全采出的情况，开展了采场地压规律的动态监测。应用YZY型钻孔应力传感器和二次接收仪测量采场地压变化，采用电子数显式收敛计量测围岩变形，得出了顶底往开采地压变化的一般规律，为选择合理的矿柱开采方案和地压控制措施提供了科学的依据。     

A new direct version of the Cook-Mayne method for wind pressure probabilities in temperate storms

The original Cook-Mayne (CM) method for obtaining a wind pressure or load of a prescribed probability is reviewed. A new direct calculation method is introduced. This does not require either Monte Carlo simulations or the assumption that extreme pressures conform to the ultimate Fisher-Tippett Type I asymptote. The required value is calculated directly with no intermediate stages. The new method still relies on the original assumptions that both the pressure coefficient and the wind dynamic head have extremes which conform to the ultimate FT1 asymptote.Violation of these two assumptions is studied in some cases where calculations based on these assumptions are compared with exact results. The direct CM method is found to retain accuracy in spite of departures from the assumptions and therefore can provide a robust design tool.