例析用不等式组模型解决现实生活中的方案设计问题

不等式组与方程组一样,是解决现实生活中的重要模型,主要涉及经济类、劳力分配、方案设计等方面的问题,是中考的热点题型,下面精选几例加以分析.一、服装生产方案问题例1下岗职工王阿姨利用自己的一技之长开办了"爱心服装厂",计划生产甲、乙两种型号的服装共40套投放到市场销售.已知甲型服装每套成本34元,售价39元;乙型服装每套成本42     

多维评价主观判断的有效性研究

本文以灰色系统理论为基础,把专家主观判断的结果表征为“区间灰数”,用灰数统计方法进行统计分析,建立了评价专家主观判断有效性的灰色模型,该模型具有良好的可操作性和有效性．     

一类投资项目评估与选择问题的数学模型

章给出在模糊环境下求解带有平衡条件的投资项目评估与选择问题的数学模型，用模糊来描述决策人对项目的主观评价以及多个评价因素的综合，用模糊整数规划模型描述了各种不同门类利益间的平均。     

做数学趣题,学思想方法

<正>问题1某服装店在一次促销大甩卖活动中,同时将甲、乙两件价格相同的服装卖给一名顾客,其中甲服装赚了50%,乙服装赔了30%.问在与这名顾客的交易中,该服装店是赚了还是赔了?你是否认为肯定是赚了?如果是那样的话,那你就错了!具体分析如下:设甲、乙两服装的售价均为a元,由题意可知甲服装的进价为a/(1+0.5)=(2/3)a(元),乙服     

基于BP神经网络及灰色GM(1,1)模型的服装供应链第三方库存预测应用研究

在由服装制造企业及品牌代理商组成的服装供应链中,第三方物流企业可以通过预测模型优化服装物流资源,提升服装供应链末端运营效率.首先提出了服装供应链管理企业库存运营模式.其次,以第三方服装供应链管理企业实际库存数据为基础,依据服装行业变化快、季节性强、多批次、小批量的特性,针对服装产品因季节性产生的"爆仓"问题,建立基于BP神经网络的第三方物流企业库存改进预测模型.第三,将预测结果误差较大的部分运用灰色GM(1,1)模型进行补充研究,通过预测结果与实际数据的对比,验证针对服装供应链末端预测库存的有效模型.改进预测模型可以辅助第三方服装类物流企业进行科学决策,为提升供应链末端效率及物流管理整体水平提供新思路.     

多属性决策的组合赋权优化方法

针对多属性决策中属性权重的确定问题，提出了一种主观权重与客观权重的集成方法。对每个决策属性，将各个决策者给出的主观权重和客观权重作为样本点，采用规划的方法来集成主观权重和客观权重，使决策结果更加可靠、可信。     

服装供应链牛鞭效应仿真研究

根据系统动力学建模原理,构建了由S服装公司、直营店和加盟商组成的二级服装供应链系统动力学模型,通过改变模型中S公司的库存调整时间、库存覆盖周期以及运输延迟时间,观察系统模拟仿真运行结果中的订单波动、累计缺货变动情况,提出改善牛鞭效应和削弱累计缺货的措施.研究结果为S服装公司库存控制与优化提供了理论依据,对服装供应链库存控制亦有参考价值.     

基于分支定界组合权的综合评价方法

提出一种将主观权重区间和客观权重相结合的线性加权组合权确定方法.通过数学规划模型,不断寻找与组合权重综合评价结果序关系最为接近的主观权重,并由此采用分支定界思想优化主观权重区间,得到具有序关系一致性的最优主观权重.算例分析表明,优化后的主观权重、客观权重和组合权的综合评价结果将带来被评价对象序关系的一致性,验证了该综合评价方法的科学性.     

基于混合模糊数的TOPSIS方法及产能过剩评价

利用区间数和三角模糊数可将定性指标定量化,从而构建多属性的混合指标体系.在多指标的评价体系中,权重的大小对评价的结果是非常重要的,本文给出了一种融合主观和客观的组合权重TOPSIS法.以七大过剩行业为研究对象,用AHP方法求出主观权重,利用模糊数将一些定性指标定量化,用变异系数法求出客观权重建立以主观、客观指标为约束条件的优化模型,求出组合权重的最优解,并将其应用于TOPSIS评价方法中,分析七大行业在2016-2018年的产能过剩程度,最后给出结果分析及对策建议.     

基于模糊理论的改进TOPSIS法在工程项目评标中的应用

评标过程会涉及到大量的定性分析,定性分析过程中受到专家的经验知识和主观判断的影响较大,因而所确定的指标权重和指标值带有较强的主观模糊性,易造成评标决策的失误.基于模糊数能量化主观模糊性并融合到指标权重与指标值中,采用模糊理论对TOPSIS法进行改进,评价指标权重和指标值均用梯形模糊数表示,建立基于模糊TOPSIS法的评标模型.结果表明,依据CC值不仅可以对投标人排序,而且还能客观的反应出投标人自身的优劣,避免了劣中选优的情况发生.最后通过示例对提议模型的应用过程及可行性进行了说明.     

Modeling of thermal comfort in air conditioned rooms by fuzzy regression analysis

Thermal comfort is a vague and subjective term. Thermally comfortable is not only influenced by the physical environment but also influenced by individual feelings and perception, which is completely subjective and is generally expressed in linguistic terms. Traditional statistic approaches cannot handle these subjective aspects effectively. Fuzzy sets appear to be ideally suited for the modeling of this partially subjective system. To illustrate the effectiveness of fuzzy regression, two particularly fuzzy regression approaches were used to model thermal comfort. To obtain the needed data, experiments were first carried out. The influencing factors considered in the experiments included both the environment influences and the individual differences such as metabolic rate. The results are analyzed and the influence of individual feeling or perception plays an important role in the experimental results and in the modeling.     

生活环境感知评价体系的构建及实证分析

传统的生活环境监测指标虽然涉及多个方面,但具有一定的局限性,不能考虑居民对生活环境的主观感受.以生活环境感知为研究对象,从自然环境、社会环境、居住环境和人际关系软环境4个维度构建了全新的生活环境感知研究体系.调查结果基于北京市两次调研数据,2009及2013年,第一次实现了感知指数的可比较性,均采用Fuzzy AHP方法对调查数据进行模型分析,对前后两个年份的民众生活环境感知进行尝试性探索和分析.     

热防护服-空气-皮肤热传导模型及其解析解

建立了高温环境下热防护服-空气-皮肤的热传导模型.利用热传导时,层合界面间温度相等和热流量连续的条件,结合微分思想,用分离变量法推导了微小时间段内模型热传导的解析解,然后通过循环得到整个时域内的解析解.利用求得的解析解分析了在80 ℃的环境温度下模型各位置温度和热流密度的变化情况,以及在不同环境温度下皮肤表面温度变化和热损伤情况.该求解方法可用来分析一般层合结构传热问题,计算结果对热防护服的设计和效果评价具有一定的参考意义.     

“后配额时代”中国纺织品服装出口预测

本文利用单整自回归移动平均模型,依据2000年1月至2004年12月中国纺织品服装出口额数据,对2005年和2006年中国纺织品服装出口走势进行预测分析。     

Stocking of Prescribed Sizes of an Item

In this paper we consider an item that is sold in a number of different prescribed sizes, an example being an item of clothing. We first deal with the situation where the total demand for a forthcoming period is known accurately but only historical or subjective estimates of the fractions of demand in each size are available. A procedure is developed for optimally allocating a given stock budget among the different sizes. Its performance is compared with a simpler, proportional allocation scheme. The numerical examples include data on clothing provided by a major municipal organization. The case where the total demand is a random variable is also treated.     

Evaluation of thermal comfort conditions in a classroom equipped with radiant cooling systems and subjected to uniform convective environment

The aim of this work is to evaluate numerically the human thermal response that 24 students and 1 teacher feel in a classroom equipped with radiant cooling systems and subjected to uniform convective environments, in lightly warm conditions. The evolution of thermal comfort conditions, using the PMV index, is made by the multi-nodal human thermal comfort model.In this numerical model, that works in transient or steady-state conditions and simulates simultaneously a group of persons, the three-dimensional body is divided in 24 cylindrical and 1 spherical elements. Each element is divided in four parts (core, muscle, fat and skin), sub-divided in several layers, and protected by several clothing layers. This numerical model is divided in six parts: human body thermal system, clothing thermal system, integral equations resolution system, thermoregulatory system, heat exchange between the body and the environment and thermal comfort evaluation.Seven different radiant systems are combined to three convective environments. In the radiant systems (1) no radiant system without warmed curtain, (2) no radiant system with warmed curtain, (3) radiant floors cooling system with warmed curtain, (4) radiant panels cooling system with warmed curtain, (5) radiant ceiling cooling system with warmed curtain, (6) radiant floor and panels cooling system with warmed curtain and (7) radiant ceiling and panels cooling system with warmed curtain are analysed, while in the convective environments (1) without air velocity field and with uniform air velocity field of (2) 0.2 m/s and (3) 0.6 m/s are also analysed. The internal air temperature and internal surfaces temperature are 28 °C, the radiant cooling surfaces temperature are 19 °C and the warmed internal curtains surfaces temperatures, subjected to direct solar radiation, are 40 °C.The numerical model calculates the Mean Radiant Temperature field, the human bodies’ temperatures field and the thermal comfort level, for the 25 occupants, for the 21 analysed situations.Without uniform air velocity field, when only one individual radiant cooling system is used, the Predicted Percentage of Dissatisfied people is lowest when the radiant floor cooling system is applied and is highest when the radiant panel cooling system is applied. When are combined the radiant ceiling or the floor cooling systems with the radiant panel cooling system the Predicted Percentage of Dissatisfied people decreases.When the uniform air velocity increases the thermal comfort level, that the occupants are subjected, increases. When the radiant floor cooling system or the combination of radiant floor and panel cooling systems without uniform air velocity field is applied, the Category C is verified for some occupants. However, with a convective uniform air velocity field of 0.2 m/s the Category B is verified and with a convective uniform air velocity field of 0.6 m/s the Category A is verify for some occupants. In the last situation the Category C is verified, in general, for all occupants.     

Towards a constructive approach to act-conditional subjective expected utility models

In structuring a decision problem under uncertainty, the uncertain environment may be affected by the choice of an act. In decision analysis, the decision maker provides subjective probabilities and utilities through separate elicitation processes, and then both components are combined together to give an index of his preference over decision alternatives. Based upon this conceptualisation of decision analysis, a constructive approach to act-conditional subjective expected utility theory is proposed. Two utility models have been addressed: the linear utility model and the weighted utility model.     

Aggregation of analytic hierarchy process models based on similarities in decision makers’ preferences

The analytic hierarchy process is widely used in both individual and group decision making environments. In this paper we investigate its applicability to model a specific class of decentralized decision problems where many decision makers take individual subjective decisions using locally available information. In such subjective decision making environments, it is neither possible nor appropriate to use group preference aggregation techniques to model the problem as a single group decision problem. An approach to identify homogeneous subgroups of decision makers based on similarities in preferences and to aggregate preferences within each subgroup is proposed. This approach is validated using employment preferences of 70 subjects modeled using the analytic hierarchy process.     

Novel reliability-based optimization method for thermal structure with hybrid random,interval and fuzzy parameters

In this paper, novel reliability-based optimization model and method are proposed for thermal structure design with random, interval and fuzzy uncertainties in material properties, external loads and boundary conditions. Random variables are used to quantify the probabilistic uncertainty with sufficient sample data; whereas, interval variables and fuzzy variables are adopted to model the non-probabilistic uncertainty associated with objective limited information and subjective expert opinions, respectively. Using the interval ranking strategy, the level-cut limit state function is precisely quantified to represent the safety state. The eventual safety possibility is derived based on multiple integral, where the cut levels of different fuzzy variables are considered to be independent. Then a hybrid reliability-based optimization model is established with considerable computational cost caused by three-layer nested loop. To improve the computational efficiency, a subinterval vertex method is presented to replace the inner-loop and middle-loop. Comparing numerical results with traditional reliability model, a mono-objective example and a multi-objective example are provided to demonstrate the feasibility of proposed method for hybrid reliability analysis and optimization in practical engineering.     

基于ANP-SVR的高校新专业设置优化分析

随着新专业的设置问题越来越多地成为各个高校普遍面对的发展问题,人们逐渐意识到决策过程中的滞后性、盲目性、片面性问题给专业设置工作乃至于该专业的生命力和竞争力带来的负面影响.运用ANP-SVR算法深入分析了高校新专业设置过程中的主要问题及其内部包含的各种因素,利用10个专业进行建模分析,并利用SVR,算法对3个拟建专业进行回归分析,得到了理想结果.方法将主观决策数字化,为高校的决策者提供了一种解决问题的新方法.