核心企业主导型供应链金融的序贯互惠博弈模型

以DK序贯互惠博弈模型为基础,在一般化假设基础上,构建了核心企业提供供应链金融支持的供应商与核心企业合作行为的两阶段序贯互惠模型。推导得出了在供应商完全理性假设条件下和具有互惠动机条件下供应商与核心企业博弈行为的序贯互惠均衡(sequential reciprocity equilibrium,SRE),并在此基础上提出命题1、2、3,分别指出供应商具有完全理性、供应商具有互惠动机但核心企业不提供支持与核心企业提供支持三种情形下的合作行为。最后,算例验证了论文所得结论。该研究结论将对供应链金融合作关系决策提供积极的参考价值。     

基于乘客选择行为的双航班竞争动态定价模型

将乘客分为两类:对时间敏感的乘客和对价格敏感的乘客。以提供同一航线的两个不同航班为研究对象,从乘客在两航班的选择行为出发,建立了竞争环境下动态定价博弈模型。通过假设两航班间具有完全信息,证明了价格均衡的存在,给出了均衡价格满足的条件,并探讨了模型求解的方法及相关性质,为航空公司价格决策提供依据。应用算例求出了给定初始库存时两航空公司各阶段的均衡价格及期望收益,对比了均衡策略及另外两种策略,并得出一些管理启示。     

确定需求时上游层面VMI利益分配机制研究

假设外界需求确定,充分考虑实施VMI后,订货主动权的转移导致订货策略的变化,以及制造商对各零部件需求速率的不同导致订货周期也不一致的现象,建立供需方在传统库存模式与VMI模式下的经济效果模型,得出VMI可使供应链上游层面整体受益的结论。在此基础上,区分供应商与制造商在合作中经常出现的3种情境——平等、供应商占优、制造商占优,利用Stackelberg博弈、纳什均衡等理论,构建上游层面VMI模式下各情境的利益分配机制,该机制最终体现在供应商所售产品的重新定价上,此定价既能弥补供应商因管理制造商库存而增加的成本,又可使制造商的利润得到保障,达到共赢的目标,同时,还可为如何在价格层面制定激励策略提供理论参考。     

易逝品供应链回购激励机理研究

运用委托代理理论对易逝品供应链中完全信息条件下基于批发价格c与回购价格b的激励机理进行了研究,并基于不完全契约理论给出了可行回购契约的具体形式,得出结论:(1)该回购激励价格组合能够在最大化供应链总期望收益的基础上达到对该收益的任意分配比例;(2)该回购机制事实上是一个具有不唯一子博弈均衡解的"讨价还价博弈模型",均衡解取决于双方的贴现因子;(3)该回购机制是共享供应链收益的一个可行的实施方式.分析并证明了不对称信息下该回购机制不能使供应链收益达到Pareto最优,这从一个侧面说明了信息共享障碍在供应链中的危害性以及消除的必要性和困难性.     

双种群可再生资源与生产资本的最优管理

本文在投资可逆的假设下建立了双种群可再生资源与生产资本的双重最优管理模型,证明了互惠(独立)双种群沿着最优轨线具有正的影子价格而股本资本具有非负的影子价格,分析了四种可能的状态轨线类型及其关系,最后给出长期最优均衡的求解方法。     

股价波动率具有模型不确定的最优消费与投资问题

本文在连续时间模型假设下,研究股票价格波动率具有模型不确定对投资者的最优消费和投资策略的影响.首先在股票价格波动率具有模型不确定的条件下,建立最优消费与投资问题的随机控制数学模型,得到了最优消费与投资所满足的HJB方程,并在常相对风险厌恶效用的情形下,获得了最优化问题值函数的显式解.其次当波动率具有模型不确定时,得到了含糊厌恶的投资者是基于股价波动率的上界作出决策的结论,并给出了投资者的最优投资和消费与含糊对冲需求.最后在给定参数的条件下,对所得结果进行了数值模拟和经济分析.     

噪声为厚尾过程的非参数函数变点的小波估计

本文给出了随机设计下非参数回归模型中噪声为无穷方差过程的小波检测和估计方法。利用基于经验小波系数的检验统计量,在原假设成立的条件下,推导出任意尺度上检验的临界值,证明了检验的一致性;在备择假设成立的条件下,得到变点个数、变点位置的相合估计与收敛速度。数值模拟以及IBM股票数据实例分析的结果均表明方法是有效的。     

新产品质量对闭环供应链再制造模式选择的影响

研究了新产品质量对闭环供应链回收再制造模式选择的影响。借助博弈论,建立了原制造商外包再制造和授权再制造的Stackelberg博弈模型,利用逆向归纳法解得两个模型的均衡解和供应链利润,并对均衡结果进行了比较分析。研究发现：外包再制造模式的供应链利润、消费者剩余、社会福利均优于授权再制造模式。原制造商选择外包再制造模式的利润要高于授权再制造模式,而第三方制造商最优策略受再制品价值折扣与新产品质量的影响。当再制品价值折扣系数与回收规模满足一定条件,而且新产品质量较高时,原制造商采取外包模式对环境更加友好。     

部分线性模型非参数部分的多项式关系检验

对于部分线性模型中非参数部分是否为某一特定阶数的多项式函数的检验问题,本文基于比较原假设与备择假设下模型拟合的残差平方和的思想构造了检验统计量,给出了计算检验p-值的精确方法和三阶矩x2逼近方法.另外我们讨论了广义似然比检验统计量的构造,并给出了其在原假设下的渐近分布.最后通过数值模拟验证了我们所提检验方法的有效性.     

基于能量最大化的磷酸亚铁锂电池组均衡策略研究

为了解决磷酸亚铁锂电池因开路电压(OCV)曲线较为平坦而无法用OCV判断电池组不一致性的问题,提出了一种基于电池能量的电池组均衡判据.基于此判据,提出了电池组可用容量和能量最大化的双重均衡目标,并设计了一种与充电机交互的改进型均衡控制策略,用此策略可在不降低整组电池可用能量的基础上实现组内电池在充电末期达到同时充满的效...     

Sorption of copper(II) ion from aqueous solution by Tectona grandis l.f. (teak leaves powder)

Studies on a batch sorption system using Tectona grandis l.f. as adsorbent was investigated to remove copper(II) from aqueous solutions. The adsorption experiments were performed under various conditions such as different initial concentrations, pH, adsorbent dosage and adsorbent particle size. The data showed that 0.1 g of Tectona grandis l.f. was found to remove 71.66% of 20 mg/L copper(II) from 30 mL aqueous solution in 180 min. The experimental equilibrium data were adjusted by the adsorption isotherms from Langmuir and Freundlich models and their equilibrium parameters were determined. The best-adjusted model to the experimental equilibrium data for Tectona grandis l.f. was the Langmuir model. Using the Langmuir model equation, the monolayer sorption capacity of Tectona grandis l.f. was evaluated and found to be 95.40 mg/g. The optimum pH value was found to be 5.5. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The dynamic data fitted the pseudo-second-order kinetic model.     

The effect of microbial selection on the occurrence-abundance patterns of microbiomes

Theoretical models are useful to investigate the drivers of community dynamics. In the simplest case of neutral models, the events of death, birth and immigration of individuals are assumed to only depend on their abundance—thus, all types share the same parameters. The community level expectations arising from these simple models and their agreement to empirical data have been discussed extensively, often suggesting that in nature, rates might indeed be neutral or their differences might not be important. However, how robust are these model predictions to type-specific rates? Also, what are the consequences at the level of types? Here, we address these questions moving from simple neutral communities to heterogeneous communities. For this, we build a model where types are differently adapted to the environment. We compute the equilibrium distribution of the abundances. Then, we look into the occurrence-abundance pattern often reported in microbial communities. We observe that large immigration and biodiversity—common in microbial systems—lead to such patterns, regardless of whether the rates are neutral or non-neutral. We conclude by discussing the implications to interpret and test empirical data.     

Removal of Reactive Red 195 from aqueous solutions by adsorption on the surface of TiO2 nanoparticles

Nanoparticles of TiO₂ were synthesized and characterized by XRD, BET, TG/DTA and TEM measurements. The commercial azo dye Reactive Red 195 (RR195) was selected as a model dye in order to examine the adsorption capacity of TiO₂ at room temperature, under dark conditions. It was demonstrated that RR195 could be efficiently adsorbed in aqueous suspension of TiO₂. A study on the effects of various parameters like initial pH, concentration of dye and concentration of adsorbent has been carried out in order to find optimum adsorption conditions. The optimum pH of sorption was 3. Substantial reduction of COD, besides removal of colour, was also achieved. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Equilibrium data fitted very well with the Langmuir model signifying the energetic homogeneity of TiO₂ surface adsorption sites. At the temperature of 30 °C, the maximum monolayer adsorption capacity obtained from the Langmuir model is 87 mg/g (pH 3.0). Kinetic studies were carried out and showed a rapid sorption of dye in the first 30 min while equilibrium was reached at 1 h. Three kinetic adsorption models were used to describe the kinetics data, the pseudo-first-order model, the pseudo-second-order model and the intraparticle diffusion model. The sorption kinetics of dye was best described by the pseudo-second-order kinetic model.     

Dye removal by almond shell residues: Studies on biosorption performance and process design

The objective of this research paper is to assess the biosorption potential of almond shell residues for methyl orange dye. The pseudo-second-order kinetic model described the dye biosorption process with a good fitting. The relationship between the pseudo-second-order model constants and the biosorption performance was also evaluated. The equilibrium data fit well with the Langmuir isotherm model presenting that the biosorption was the monolayer coverage of dye on the biosorbent and the homogeneity of active sites for dye binding on the biosorbent surface. Based on the Langmuir model, a single-stage batch biosorber was also designed to predict the biosorbent mass for certain percentage dye removal. Besides, the standard Gibbs free energy change was also calculated to define the nature of biosorption process. These results revealed that the utilization of almond shell residues as dye biosorbent could be an interesting option from both environmental and economic point of view.     

A generalized dimensionless local power-law correlation for refrigerant flow through adiabatic capillary tubes and short tube orifices

This paper presents a new method to obtain generalized dimensionless correlation of refrigerant mass flow rates through adiabatic capillary tubes and short tube orifices. The dimensionless Pi groups were derived from the homogeneous equilibrium model, which is available for different refrigerants entering adiabatic capillary tubes or short tube orifices as the subcooled liquid, two-phase mixture, or supercritical fluid. To mitigate the potential over-fitting risk in neural network, a new “local” power-law correlation reformed from the homogeneous equilibrium model was proposed and compared with the conventional “global” power-law correlation and recently developed neural network model. About 2000 sets of experimental mass flow rate data of R12, R22, R134a, R404A, R407C, R410A, R600a and CO₂ (R744) in the open literature covering capillary and short tube geometries, subcritical and supercritical inlet conditions were collected for the model development. The comparison between the recommended six-coefficient correlation and experimental data reports 0.80% average and 8.98% standard deviations, which is comparable with the previously developed neural network and much better than the “global” power-law correlation.     

Characterizations of strontium(II) and barium(II) adsorption from aqueous solutions using dolomite powder

In this research, adsorption technique was applied for strontium and barium removal from aqueous solution using dolomite powder. The process has been investigated as a function of pH, contact time, temperature and adsorbate concentration. The experimental data was analyzed using equilibrium isotherm, kinetic and thermodynamic models. The isotherm data was well described by Langmuir isotherm model. The maximum adsorption capacity was found to be 1.172 and 3.958 mg/g for Sr(II) and Ba(II) from the Langmuir isotherm model at 293 K, respectively. The kinetic data was tested using first and pseudo-second order models. The results indicated that adsorption fitted well with the pseudo-second order kinetic model. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were also determined using the equilibrium constant value obtained at different temperatures. The results showed that the adsorption for both ions was feasible and exothermic.     

Equilibrium and kinetic studies of methyl violet sorption by agricultural waste

In this work, sunflower (Helianthus annuus L.) seed hull (SSH), an agricultural waste, was evaluated for its ability to remove methyl violet (MV) from aqueous solutions. Sorption isotherm of MV onto the SSH was determined at 30 degrees C with the initial concentrations of MV in the range of 25-300 mg/L. The equilibrium data were analyzed using the Langmuir, Freundlich and Temkin isotherm models. The equilibrium process was described well by the Freundlich isotherm model. The maximum SSH sorption capacity was found to be 92.59 mg/L at 30 degrees C. The kinetic data were studied in terms of the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The pseudo-second-order model best described the sorption process. A single-stage batch-adsorber design of the adsorption of MV onto SSH was studied based on the Freundlich isotherm equation. The results indicated that sunflower seed hull was an attractive candidate for removing methyl violet from aqueous solution.     

Applications of Brazilian pine-fruit shell in natural and carbonized forms as adsorbents to removal of methylene blue from aqueous solutions--kinetic and equilibrium study

The Brazilian pine-fruit shell (Araucaria angustifolia) is a food residue, which was used in natural and carbonized forms, as low-cost adsorbents for the removal of methylene blue (MB) from aqueous solutions. Chemical treatment of Brazilian pine-fruit shell (PW), with sulfuric acid produced a non-activated carbonaceous material (C-PW). Both PW and C-PW were tested as low-cost adsorbents for the removal of MB from aqueous effluents. It was observed that C-PW leaded to a remarkable increase in the specific surface area, average porous volume, and average porous diameter of the adsorbent when compared to PW. The effects of shaking time, adsorbent dosage and pH on adsorption capacity were studied. In basic pH region (pH 8.5) the adsorption of MB was favorable. The contact time required to obtain the equilibrium was 6 and 4h at 25 degrees C, using PW and C-PW as adsorbents, respectively. Based on error function values (F(error)) the kinetic data were better fitted to fractionary-order kinetic model when compared to pseudo-first order, pseudo-second order, and chemisorption kinetic models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. For MB dye the equilibrium data were better fitted to the Sips isotherm model using PW and C-PW as adsorbents.     

Microstructural evolution and tensile property of 1Cr15Ni36W3Ti superalloy during thermal exposure

1Cr15Ni36W3Ti was thermally exposed at 580 ℃ and 680 ℃,respectively,up to 3000 h.The γ'phase and intergranular TiC carbides continuously coarsened during exposure.None of η,laves or σ phase was discovered in the exposed samples,indicating good microstructure stability under the present exposure conditions.The ripening process of the γ'phase could be well modelled utilizing the LSW theory.The evolutions of the yield and tensile strengths were monotonous during exposure at 580 ℃.However,a transition point in strengths was detected in the tensile samples exposed at 680 ℃ for 300 h.Accordingly,the critical γ'diameter was measured to be 13-14 nm.The γ'/dislocations interaction mechanism transformed from shearing to looping with the γ'diameter exceeding the critical point.The combination of the weakly coupled dislocations model and the Orowan looping model yielded a critical diameter of 13.1 nm which coincided well with the measured one,indicating the applicability of these two strengthening models for 1Cr15Ni36W3Ti.The present exposure conditions did not exert a profound effect on the fracture mode.All the tensile samples underwent a typically ductile fracture with a dimple pattern dominating the fracture surface.The dispersed deformation induced by the prevalence of dislocation looping in the over-aged tensile samples retarded the propagation of intergranular cracks.The declined precipitation hardening increment and the enhanced deformation homogeneity partially recovered the tensile ductility in the over-aged samples exposed at 680 ℃.     

Competitive adsorption of Cu (II), Co (II) and Ni (II) from their binary and tertiary aqueous solutions using chitosan-coated perlite beads as biosorbent

A new composite chitosan-coated biosorbent was prepared and was used for the removal and recovery of heavy metals from aqueous solution. In the present investigation, equilibrium adsorption characteristics of Cu (II), Ni (II), and Co (II) from their binary and tertiary solution on newly developed biosorbent chitosan-coated perlite beads were evaluated through batch and column studies. These beads were characterized by using FTIR, EDXRF and surface area analysis techniques. The effect of various biosorption parameters like effect of pH, agitation time, concentration of adsorbate and amount of adsorbent on extent of adsorption was investigated. The adsorption follows Lagergren first order kinetic model. The equilibrium adsorption data were fitted to Freundlich and Langmuir adsorption isotherm models and the model parameters were evaluated. Both the models represent the experimental data satisfactorily. The sorbent loaded with metal was regenerated with 0.1N NaOH solution. Furthermore the column dynamic studies indicate the re-usage of the biosorbent.