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.     

Crisis communication,anticipated food scarcity,and food preferences: Preregistered evidence of the insurance hypothesis

Whereas large-scale consumption of energy-dense foods contributes to climate change, we investigated whether exposure to climate change-induced food scarcity affects preferences toward these foods. Humans’ current psychological mechanisms have developed in their ancestral evolutionary past to respond to immediate threats and opportunities. Consequently, these mechanisms may not distinguish between cues to actual food scarcity and cues to food scarcity distant in time and space. Drawing on the insurance hypothesis, which postulates that humans should respond to environmental cues to food scarcity through increased energy consumption, we predicted that exposing participants to climate change-induced food scarcity content increases their preferences toward energy-dense foods, with this effect being particularly pronounced in women. Three experiments—including one preregistered laboratory study—confirm this notion. Our findings jointly demonstrate that receiving information about food shortages distant in time and space can influence current food preferences.     

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.     

A review of topic modeling methods

Topic modeling is a popular analytical tool for evaluating data. Numerous methods of topic modeling have been developed which consider many kinds of relationships and restrictions within datasets; however, these methods are not frequently employed. Instead many researchers gravitate to Latent Dirichlet Analysis, which although flexible and adaptive, is not always suited for modeling more complex data relationships. We present different topic modeling approaches capable of dealing with correlation between topics, the changes of topics over time, as well as the ability to handle short texts such as encountered in social media or sparse text data. We also briefly review the algorithms which are used to optimize and infer parameters in topic modeling, which is essential to producing meaningful results regardless of method. We believe this review will encourage more diversity when performing topic modeling and help determine what topic modeling method best suits the user needs.     

Secondary school educators' perceptions and practices in handling cyberbullying among adolescents: A cluster analysis

School educators play an important role in cyberbullying management. Since scarce earlier research indicated low perceived competence of school educators in handling cyberbullying, more insight is needed in what determines their actions and how to improve these practices. This study assessed school educator practices, their perceptions and context factors from a behavior change theoretical framework, and investigated educator clusters related to this. An online survey was conducted among 451 secondary school educators (teachers, principals, school counselors). School educators mostly used recommended actions (i.e. conversations with pupils, enlisting professionals for support, parental involvement, providing supportive victim advice). Four educator clusters were identified: ‘referrers’ (65%), ‘disengaged’ educators (14%), ‘concerned’ educators (12%) and ‘use all means’ educators (9%). The first two clusters were less adept at handling cyberbullying and comprised mostly teachers, particularly indicating a need for training teachers. Our findings show a need for tailored educator training, e.g. by job position, gender, school size and grade. The behavior change theoretical framework can help target educators' particular needs.     

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.     

焦炉煤气正、负压HPF脱硫工艺比较

对正、负压HPF脱硫工艺进行工艺特点和经济比较,并对2种工艺的设备、产品、原材料及消耗指标进行了对比,分析可知,操作运行费用2种工艺相当,而建设费用HPF正压脱硫工艺具有优势,因此,正压脱硫在焦化行业中应用广泛。     

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.