Superconducting first‐order pairing: Finite‐temperature simulations

A recently developed first‐order mechanism for superconducting pairing has been extended from T = 0 K to finite temperatures. On the basis of quantum statistical considerations, we have suggested a direct pairing interaction that does not necessarily involve second‐order elements, such as the electron–phonon coupling or specific magnetic interactions submitted by spin fluctuations. The driving force for the (energy‐driven) first‐order pairing is an attenuation of the destabilizing influence of the Pauli antisymmetry principle (PAP). Only the moves of unpaired fermions are controlled by the PAP, while the moves of superconducting Cooper pairs are not. The quantum statistics of Cooper pairs is of a mixed type, as it combines fermionic on‐site and bosonic intersite properties. The strong correlation between the strength of PAP constraints and system topology in combination with the electron number has been discussed for some larger clusters. Detailed finite‐temperature simulations on first‐order pairing have been performed for four‐center–four‐electron clusters with different topologies. A canonical ensemble statistics has been employed to derive the electronic energy, the electronic configuration entropy, and the free energy of paired and unpaired states in thermal equilibrium. The simulations show that pairing can be caused by either the electronic energy or the electronic configuration entropy. The coexistence of two different sets of quantum particles in paired states (i.e., the Cooper pairs and the unpaired electrons) can lead to an enhanced configuration entropy. In this context, we discuss the possibility of an entropy‐driven high‐temperature superconductor emerging from a low‐temperature unpaired state. The charge and spin degrees of freedom of the four‐center–four‐electron systems have been studied with the help of the charge and spin fluctuations. The spin fluctuations are helpful in judging the validity of pairing theories based on magnetic interactions. The charge fluctuations are a measure for the carrier delocalization in unpaired and paired states. The well‐known proximity between Jahn–Teller activity and superconductivity is analyzed in the zero‐temperature limit. It is demonstrated that both processes compete in their ability to reduce PAP constraints. All theoretical results have been derived within the framework of the simple Hubbard Hamiltonian. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Day‐ahead price forecasting based on hybrid prediction model

Short‐Term Price Forecast is a key issue for operation of both regulated power systems and electricity markets. Energy price forecast is the key information for generating companies to prepare their bids in the electricity markets. However, this forecasting problem is complex due to nonlinear, nonstationary, and time variant behavior of electricity price time series. So, in this article, the forecast model includes wavelet transform, autoregressive integrated moving average, and radial basis function neural networks (RBFN) is presented. Also, an intelligent algorithm is applied to optimize the RBFN structure, which adapts it to the specified training set, reduce computational complexity and avoids over fitting. Effectiveness of the proposed method is applied for price forecasting of electricity market of mainland Spain and its results are compared with the results of several other price forecast methods. These comparisons confirm the validity of the developed approach. © 2016 Wiley Periodicals, Inc. Complexity 21: 156–164, 2016     

单链需求扰动下竞争供应链决策模型研究

突发事件经常导致需求扰动,致使供应链运营出现失调.以两条竞争供应链组成的供应链系统为研究对象,建立了供应链竞争基准模型.引入偏差惩罚成本,构建了竞争供应链应对单链需求扰动的均衡模型,给出了不同扰动程度下生产数量及零售价格的应对策略.研究发现,在一定的扰动程度内,原生产计划都具有鲁棒性,鲁棒性范围依赖于价格交叉弹性系数和偏离惩罚成本,其大小与需求扰动源无关.     

城市交通运输系统的碳排放交易货币化模型研究

在全球构建碳排放交易市场的热潮下,我国也在积极推进全国碳排放权交易市场建设,并将交通运输行业纳入构建碳排放交易市场的重点行业.在城市交通运输系统加入碳排放交易市场的假设前提下,基于对城市交通运输系统碳排放交易货币总额研究的角度,对城市交通运输系统客流构成进行分析,构建城市交通运输系统碳排放交易量的计算公式,并将二氧化碳作为一种特殊的生产要素,引入影子价格的计算公式,提出适合城市交通运输系统碳排放影子价格的计算公式,最终组合构建城市交通运输系统碳排放交易货币化模型.模型以重庆市轨道交通3号线为例,验证了模型可行性.     

Pricing Asian options of discretely monitored geometric average in the regime‐switching model

This paper provides analytic pricing formulas of discretely monitored geometric Asian options under the regime‐switching model. We derive the joint Laplace transform of the discount factor, the log return of the underlying asset price at maturity, and the logarithm of the geometric mean of the asset price. Then using the change of measures and the inversion of the transform, the prices and deltas of a fixed‐strike and a floating‐strike geometric Asian option are obtained. As the numerical results, we calculate the price of a fixed‐strike and a floating‐strike discrete geometric Asian call option using our formulas and compare with the results of the Monte Carlo simulation. Copyright © 2016 John Wiley & Sons, Ltd.     

基于GA-SVR算法的淀粉价格预测研究

近年来我国淀粉产业迅速发展,给相关企业带来了巨大经济效益的同时,由于其情况复杂,致使相关企业无法正确掌控淀粉价格的走势,也造成了大量的经济损失.因此,寻找一种科学的、高效的淀粉价格预测方法已成为当务之急.将遗传算法(GA)与回归型支持向量机(SVR)相融合,建立了GA-SVR淀粉价格预测模型.对2003-2011年淀粉价格进行仿真预测,结果表明,模型的决定系数和均方误差均优于其它方法,验证了模型的有效性与优势.     

关于Guzowska-Luís-Elaydi模型的分岔

本文考虑了一个离散的Logistic竞争模型.为了讨论分岔,给出了不动点的拓扑类型及非双曲的情况.应用中心流行约化定理,证明了跨临界分岔会在三个不动点上发生.本文还证明了在两个不动点处,跳跃分岔会发生,同时稳定的周期2轨会出现.     

Dynamics of a generalized Ricker–Beverton–Holt competition model subject to Allee effects

In this article, we propose and study a generalized Ricker–Beverton–Holt competition model subject to Allee effects to obtain insights on how the interplay of Allee effects and contest competition affects the persistence and the extinction of two competing species. By using the theory of monotone dynamics and the properties of critical curves for non-invertible maps, our analysis show that our model has relatively simple dynamics, i.e. almost every trajectory converges to a locally asymptotically stable equilibrium if the intensity of intra-specific competition intensity exceeds that of inter-specific competition. This equilibrium dynamics is also possible when the intensity of intra-specific competition intensity is less than that of inter-specific competition but under conditions that the maximum intrinsic growth rate of one species is not too large. The coexistence of two competing species occurs only if the system has four interior equilibria. We provide an approximation to the basins of the boundary attractors (i.e. the extinction of one or both species) where our results suggests that contest species are more prone to extinction than scramble ones are at low densities. In addition, in comparison to the dynamics of two species scramble competition models subject to Allee effects, our study suggests that (i) Both contest and scramble competition models can have only three boundary attractors without the coexistence equilibria, or four attractors among which only one is the persistent attractor, whereas scramble competition models may have the extinction of both species as its only attractor under certain conditions, i.e. the essential extinction of two species due to strong Allee effects; (ii) Scramble competition models like Ricker type models can have much more complicated dynamical structure of interior attractors than contest ones like Beverton–Holt type models have; and (iii) Scramble competition models like Ricker type competition models may be more likely to promote the coexistence of two species at low and high densities under certain conditions: At low densities, weak Allee effects decrease the fitness of resident species so that the other species is able to invade at its low densities; While at high densities, scramble competition can bring the current high population density to a lower population density but is above the Allee threshold in the next season, which may rescue a species that has essential extinction caused by strong Allee effects. Our results may have potential to be useful for conservation biology: For example, if one endangered species is facing essential extinction due to strong Allee effects, then we may rescue this species by bringing another competing species subject to scramble competition and Allee effects under certain conditions.     

考虑市场需求不确定下的供应链协调优化

在市场需求不确定的情况下,考察市场需求依赖销售价格,建立一个由单一供应商和单一零售商组成的二级退货模型,并分别从集中决策和分散决策两方面讨论,证明单纯的退货政策无法实现供应链协调,而通过引入回馈与惩罚机制后则可以实现协调,并求出此时的最优订货量和最优售价.最后,通过数值算例证明以上的结论.     

化学青年教师实验素养的问题表现与提升路径—基于 2020年江苏省高中化学青年教师教学基本功大赛

江苏省高中化学青年教师教学基本功大赛突出了对教师实验素养的考查。大赛中对教师实验素养考查的内容有6个项目。通过观摩大赛,发现部分选手实验素养较弱,表现在化学实验安全知识“口是心非”,化学基础原理知识“似是而非”,化学实验内容设计未能体现“以生为本”,化学实验操作未能“精益求精”。分析青年教师实验素养问题的原因,提出青年教师实验素养提升的路径有:落实教师实验素养提升培训活动,开展实验创新研讨活动,突出基于实验内容的教学设计。