Coupled-mode envelope solitary waves in a pair of cubic Schrödinger equations with cross modulation: Analytical solution and collisions with application to Rossby waves

Coupled-Nonlinear Schrödinger equations, linked by cross modulation terms, arise in both nonlinear optics and in Rossby waves in the atmosphere and ocean. In this paper, we derive exact, analytic solutions for the “bright” coupled-mode soliton, for which the envelope in each mode asymptotes to zero at spatial infinity, and for its spatially periodic generalization. We then numerically study the collisions of the coupled-mode solitary wave both with a conventional envelope soliton, confined to a single mode, and also with a second coupled-mode solitary wave. The collisions are sensitive to both the relative speed and phase of the solitons. In some parameter ranges, the collisions are nearly elastic, but in others, one or both solitons fission.     

Modelling and analysis of sustainable operations management: certain investigations for research and applications

Sustainable operations management (SOM) can be defined as the operations strategies, tactics and techniques, and operational policies to support both economic and environmental objectives and goals. The subject of sustainability has gained much attention from both researchers and practitioners in the past 6–8 years. Most of the articles deal with sustainability from environmental perspectives, but a limited number of them integrate both economic and environmental implications or focus on trading-off between profitability, competitiveness and environmental dimensions. Moreover, there is a limited focus on modelling and analysis (MA) of SOM integrating and balancing the interests of both economic and environmental interests. Therefore, an attempt has been made in this paper to review the extant literature on SOM. The objective is to understand the definition of SOM and present the current status of research in MA, as well as future research directions in the field. Considering the recent focus of the subject, we review the literature on MA of SOM beginning in 2000 in order to make our study current and more relevant for both researchers and practitioners. Finally, a summary of findings and conclusions is reported.     

Creativity and interdisciplinarity: one creativity or many creativities?

Psychologists and educators frequently debate whether creativity and problem solving are domain-general—applicable to all disciplines and tasks—or domain-specific—tailored to specific disciplines and tasks. In this paper, we briefly review the major arguments for both positions, identify conceptual and empirical weaknesses of both perspectives, and describe two relatively new hybrid models that attempt to address ways in which creativity and innovation are both domain-general and domain-specific.     

考虑促销努力与生产努力的供应链召回努力策略研究

考虑一条由单个供应商和单个制造商组成的二级供应链,面对产品召回事件,供应商和制造商都可以通过召回努力来降低召回事件发生的概率。本文研究了供应链最优召回努力策略,研究发现双方的召回努力与初始期望单位召回成本和潜在市场规模有关。当潜在市场规模和初始期望单位召回成本都较小时,双方均选择部分召回努力,当潜在市场规模和初始期望单位召回成本都较大时,双方均选择全部召回努力,否则,供应商选择全额召回努力而制造商选择部分召回努力。由于制造商的促销努力与供应商的生产努力是企业扩大市场规模常用的策略,因此,本文还研究了这两种策略分别对供应链召回努力策略的影响。我们发现这两种策略都能降低双方采取全额召回努力时潜在市场规模的门槛,激励双方增加召回努力,降低产品召回概率并增加供应链成员的利润。特别的,我们还对比了这两种策略对双方召回努力的影响,发现当促销努力成本系数与生产努力成本系数都较小时,两种策略对召回努力的影响相同,当生产努力成本系数足够大时,考虑促销努力时双方的召回努力水平更高,否则,考虑生产努力时双方的召回努力水平更高。     

Inexact Two-Grid Methods for Eigenvalue Problems

We discuss the inexact two-grid methods for solving eigenvalue problems, including both partial differential and integral equations. Instead of solving the linear system exactly in both traditional two-grid and accelerated two-grid method, we point out that it is enough to apply an inexact solver to the fine grid problems, which will cut down the computational cost. Different stopping criteria for both methods are developed for keeping the optimality of the resulting solution. Numerical examples are provided to verify our theoretical analyses.     

Preference elicitation from inconsistent judgments using multi-objective optimization

Several decision-making techniques involve pairwise comparisons to elicit the preferences of a decision maker (DM). This paper proposes a new approach for prioritization from pairwise comparisons using the concept of indirect judgments. No method exists that simultaneously minimizes deviations from both direct and indirect judgments. In order to estimate preferences, it is sensible to consider both the acquired judgments and the other judgments latent in the DM’s mind. Hence, a technique is developed here to minimize the deviations from both types of judgments.     

ITERATIVE ILU PRECONDITIONERS FOR LINEAR SYSTEMS AND EIGENPROBLEMS

Iterative ILU factorizations are constructed,analyzed and applied as preconditioners to solve both linear systems and eigenproblems.The computational kernels of these novel Iterative ILU factorizations are sparse matrix-matrix multiplications,which are easy and efficient to implement on both serial and parallel computer architectures and can take full advantage of existing matrix-matrix multiplication codes.We also introduce level-based and threshold-based algorithms in order to enhance the accuracy of the proposed Iterative ILU factorizations.The results of several numerical experiments illustrate the efficiency of the proposed preconditioners to solve both linear systems and eigenvalue problems.     

Doubly Adaptive Quadrature Routines Based on Newton–Cotes Rules

In this paper we test two recently published Matlab codes, adaptsim and adaptlob, using both a Lyness–Kaganove test and a battery type of test. Furthermore we modify these two codes using sequences of null rules in the error estimator with the intention to increase the reliability for both codes. In addition two new Matlab codes applying a locally and a globally adaptive strategy respectively are developed. These two new codes turn out to have very good properties both with respect to reliability and efficiency. Both algorithms are using sequences of null rules in their local error estimators. These error estimators allow us both to test if we are in the region of asymptotic behavior and thus increase reliability and to take advantage of the degree of precision of the basic quadrature rule. The new codes compare favorably to the two recently published adaptive codes both when we use a Lyness–Kaganove testing technique and by using a battery test.     

基于电商平台的最优销售模式和退款保证策略研究

基于一个制造商和一个平台商组成的供应链,考虑消费者退货行为,运用博弈论建立了不同销售模式和退款保证策略下的六个模型。通过均衡解对比和数值算例分析,给出了制造商的最优销售模式选择和制造商与平台商的退款保证策略。研究发现:制造商同时选择转售和代理模式对其自身、平台商和消费者都最有利;在制造商同时选择两种销售模式的情况下,当转售和代理模式下客户满意度都比较高时,佣金费率对制造商和平台商的退款保证策略选择没有影响,制造商始终倾向于提供退款保证而平台商始终倾向于不提供退款保证。     

Facilitated modelling in strategy development: measuring the impact on communication,consensus and commitment

Facilitated modelling is used in supporting the resolution of strategic issues mainly because it is expected to improve communication between decision makers, foster consensus and create commitment. Researchers in both the strategy and facilitated modelling fields call for more systematic research on how strategy development works in practice and how outcomes are created. In this paper, three facilitated modelling cases on strategic issues are studied using both written questionnaires, developed in the strategy and decision support fields, and semi-structured interviews. Results of both measurement approaches are compared to determine (a) to what extent outcomes in participants’ own terms are similar to concepts in the questionnaire and (b) whether changes measured by both methods are similar. Interview results are used to assess (c) which elements of the intervention contribute to outcomes. Findings suggest that questionnaires offer clear benefits as standardized measurement of facilitated modelling outcomes.     

Measuring inefficiency for specific inputs using data envelopment analysis: evidence from construction industry in Spain and Portugal

This article contributes to the efficiency literature by defining, in the context of the data envelopment analysis framework, the directional distance function approach for measuring both technical and scale inefficiencies with regard to the use of individual inputs. The input-specific technical and scale inefficiencies are then aggregated in order to calculate the overall inefficiency measures. Empirical application focuses on a large dataset of Spanish and Portuguese construction companies between 2002 and 2010 and accounts for three inputs: materials, labor and fixed assets. The results show, first, that for both Spanish and Portuguese construction companies, fixed assets are the most technically inefficient input. Second, the most inefficient scale concerns the utilization of material input in both samples; the reason for this inefficiency is that firms tend to operate in the increasing returns to scale portion of technology set. Third, in both samples, large firms have the lowest input-specific technical inefficiencies, but the highest input-specific scale inefficiencies, compared to their small and medium-sized counterparts, and tend to suffer from decreasing returns to scale. Finally, in both samples, input-specific technical inefficiency under constant returns to scale increased during the period of the recent financial crisis, mainly due to the augmentation in scale inefficiency.

     

考虑制造商开设展厅的横向竞争博弈及定价-服务策略

从体验成本差异角度出发,将消费者分为高低体验成本两类,利用Hotelling模型构建消费者的效用函数。分析两个竞争性制造商关于开设展厅的Bertrand博弈以及展厅开设后的价格与服务决策。结果表明,当低体验成本消费者较多且产品匹配度较高或者低体验成本消费者较少时,两个制造商均开设展厅,但双方都获得最低的利润,陷入囚徒的困境;当低体验成本消费者较多且产品匹配度较低时,两个制造商都不开设展厅,双方达到帕累托最优。     

基于随机提前期的二级库存系统的优化方法

针对需求和提前期均是随机的情况下,考察了一个简单的二级库存系统,即单个供应商、单个零售商的优化问题,两者均采用s,Q策略进行库存管理,他们的订货数量Qr,Qs都是已知常数,以每计划周期内系统运行期望总费用最小建立了目标函数,寻求系统的决策变量sr,ss,最后给出了求解算法与数值算例.     

Electricity price forecasting through transfer function models

Forecasting electricity prices in presentday competitive electricity markets is a must for both producers and consumers because both need price estimates to develop their respective market bidding strategies. This paper proposes a transfer function model to predict electricity prices based on both past electricity prices and demands, and discuss the rationale to build it. The importance of electricity demand information is assessed. Appropriate metrics to appraise prediction quality are identified and used. Realistic and extensive simulations based on data from the PJM Interconnection for year 2003 are conducted. The proposed model is compared with naïve and other techniques.     

Design of fast one-pass authenticated and randomized encryption schema using reversible cellular automata

A novel way to provide fast authenticated and randomized encryption is proposed using reversible cellular automata for the first time. A block-based cryptosystem is presented and shown to provide security against both active and passive attackers by the way of a strong authentication mechanism. The proposed system is much faster than existing authenticated encryption standards since only one pass per block is performed to ensure both encryption and integrity. Experimental results show robustness of the cryptosystem against several cryptanalysis techniques, when a formal proof of strict integrity preserving is included. Obtained results demonstrate superiority of the approach in both security and rapidity aspects.     

Fatigue properties of kapron (nylon-6) and kaprolon

It is shown that kaprolon has high fatigue strength as compared with kapron (nylon-6) and other thermoplastics. This is attributable both to its high static fatigue strength and to its high fatigue coefficient. For both kapron and kaprolon a sharp increase in hysteretic heat production is observed after critical self-heating at 15° C; in this case the endurance of both materials is low.Mekhanika Polimerov, Vol. 1, No. 2, pp. 118–122, 1965     

Do the generalized polynomial chaos and Fröbenius methods retain the statistical moments of random differential equations?

The aim of this paper is to explore whether the generalized polynomial chaos (gPC) and random Fröbenius methods preserve the first three statistical moments of random differential equations. There exist exact solutions only for a few cases, so there is a need to use other techniques for validating the aforementioned methods in regards to their accuracy and convergence. Here we present a technique for indirectly study both methods. In order to highlight similarities and possible differences between both approaches, the study is performed by means of a simple but still illustrative test-example involving a random differential equation whose solution is highly oscillatory. This comparative study shows that the solutions of both methods agree very well when the gPC method is developed in terms of the optimal orthogonal polynomial basis selected according to the statistical distribution of the random input. Otherwise, we show that results provided by the gPC method deteriorate severely. A study of the convergence rates of both methods is also included.     

Peng’s maximum principle for a stochastic control problem driven by a fractional and a standard Brownian motion

We study a stochastic control system involving both a standard and a fractional Brownian motion with Hurst parameter less than 1/2. We apply an anticipative Girsanov transformation to transform the system into another one, driven only by the standard Brownian motion with coefficients depending on both the fractional Brownian motion and the standard Brownian motion. We derive a maximum principle and the associated stochastic variational inequality, which both are generalizations of the classical case.     

Optimizing source and receiver placement in multistatic sonar networks to monitor fixed targets

Multistatic sonar networks consisting of non-collocated sources and receivers are a promising development in sonar systems, but they present distinct mathematical challenges compared to the monostatic case in which each source is collocated with a receiver. This paper is the first to consider the optimal placement of both sources and receivers to monitor a given set of target locations. Prior publications have only considered optimal placement of one type of sensor, given a fixed placement of the other type. We first develop two integer linear programs capable of optimally placing both sources and receivers within a discrete set of locations. Although these models are capable of placing both sources and receivers to any degree of optimality desired by the user, their computation times may be unacceptably long for some applications. To address this issue, we then develop a two-step heuristic process, Adapt-LOC, that quickly selects positions for both sources and receivers, but with no guarantee of optimality. Based on this, we also create an iterative approach, Iter-LOC, which leads to a locally optimal placement of both sources and receivers, at the cost of larger computation times relative to Adapt-LOC. Finally, we perform computational experiments demonstrating that the newly developed algorithms constitute a powerful portfolio of tools, enabling the user to slect an appropriate level of solution quality, given the available time to perform computations. Our experiments include three real-world case studies.     

展厅模式下制造商的质量与价格竞争

根据消费者对线上产品信息的了解程度,将市场中消费者分为高信息消费者和低信息消费者,利用Hotelling模型构造消费者的效用函数,分析两个竞争性的制造商关于开设展厅的Bertrand博弈以及制造商开设展厅后的质量和价格决策,并进行均衡分析。结果表明:当开设展厅的固定成本很低或可以忽略不计时,若低信息消费者对线上产品信任度很低,两个制造商都会开设展厅,同时其最优价格以及质量都会增加,但双方都获得较低的利润,陷入囚徒的困境;若低信息消费者对线上产品信任度很高时,两个制造商都不开设展厅,双方达到帕累托最优;当低信息消费者对线上产品信任度中等时,均衡策略与市场中低信息消费者比例有关,低信息消费者较多时,都不开设展厅,低信息消费者较少时,都开设展厅。当开设展厅的固定成本达到某一值,无论市场中的低信息消费者的多少或者信任度的高低,制造商都不会开设展厅。