共查询到20条相似文献，搜索用时 109 毫秒
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传统的库存研究中都假定物品的库存费用是固定不变的.本文通过考虑库存费的变化率为库存量的函数,并在需求线性依赖于库存水平的形式下,拓展了变库存费的变质性物品的经济批量模型.然后以系统平均利润最大化为目标,讨论了在允许短缺发生且假定短缺完全拖后的情况下模型存在唯一最优解的条件.最后给出了应用实例,分析了模型主要参数的变化对最优订货策略的影响. 相似文献
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考虑通货膨胀的影响,建立了易变质物品的库存模型,其中融资模式采用存货质押融资策略。给出了模型的近似解,证明了解的存在性和唯一性。最后,用数值例子验证了库存模型的有效性。模型为库存管理提供决策参考依据。 相似文献
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本文对易变质多物品库存系统提出了两种订购策略,以系统平均费用最少为目标建立数学模型,在一定条件下给出其最优解。最后通过数值列子比较两种策略的优劣,对系统订购周期和平均成本进行了数值分析。 相似文献
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徐德英 《临沂师范学院学报》2010,32(6):13-20
研究了损失率及变质情形下可替代物品的经济订货批量问题.在计划期内,若某一种易变质物品发生缺货,则可以被另一种易变质物品以一定的替代率代替补充,不同物品有不同的变质率,且短缺量部分拖后供给.以总利润最大为目标函数,建立了一个三阶供应链模型,得到了最优订购策略.证明了最优策略存在的唯一性,并分别给出了求解最优订购策略的算法,最后通过一个算例验证了算法的最优性. 相似文献
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王燕 《兰州石化职业技术学院学报》2014,(4):43-47
VMI被越来越多的企业采用,它使企业的效率和效益得到提高。因此,VMI成为了企业库存控制的重点。建立了在VMI环境下,产品允许缺货,且当需求服从库存量函数分布时易变质品的库存控制模型,得出其最佳订货周期,求出其最优解,并对其中的参数进行分析,了解其对总成本的影响情况。 相似文献
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变质率影响下的易变质品库存模型研究 总被引：1，自引：0，他引：1
本文对果蔬食品等具有迟滞变质现象(non-instantaneous)的易变质品库存模型进行研究,以Weibll分布函数表示其在经过迟滞区后的变质特性,以总成本最低为目标建立了补货模型,确定了最优订货周期以及订货批量,并分析了各个参变量影响模型总成本的敏感度,最后还将该模型与经过迟滞区后为常变质情况的模型进行了对比. 相似文献
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常浩 《廊坊师范学院学报(自然科学版)》2012,12(3):98-101
高等数学课程是工科大学生的数学类主干课程,它的学习好坏直接影响到工科学生后续数学课程的学习效果。为了提高高等数学课程的教学效果,可尝试将数学建模思想方法融入到高等数学的实际教学过程中。以一类变质性物品的生产—库存问题为例,以数学建模思想方法为指导,应用高等数学知识去解决应用实例,对于强化学以致用的目的、培养学生的创新意识和创新能力有很大的启发性。 相似文献
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库存管理是物流管理的重要组成部分,是指一个组织对所储备的所有物品和资源进行的有效管理。库存管理不只是管理实物,更重要是管好库存成本。本文以真实的XX公司为例,阐述了良好的物流管理是如何通过控制库存的持有成本、获得成本和缺货成本。建立一套完善的物流管理体制来提高企业物流运作效益,从而加快资金回转、降低运营成本、改善客户服务水平,并最终提高企业利润。 相似文献
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Peter Zeegers 《高等教育研究与发展》2002,21(1):73-92
The Biggs' Study Process Questionnaire (SPQ), an instrument for the evaluation of student learning in higher education, was revised over a three-year period with over 2500 tertiary students. The original instrument structure of 42 items in 6 sub-scales was maintained with each item being subject to revision and assessed for internal consistency and appropriateness through a sequence of trial and retrial. The final version consists of 8 original items and 34 revised items. This version was evaluated with 996 students, at first-year and third-year level, through the use of confirmatory factor analysis using AMOS. The two models having the best fit to the data are represented by the original six sub-scale model which loads onto two higher order factors, a deep approach and a surface approach to learning, or a seven sub-scale version which loads on the same two higher order factors. Evidence is presented as to the preference of the latter model. 相似文献
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Audra E. Kosh Mary Ann Simpson Lisa Bickel Mark Kellogg Ellie Sanford‐Moore 《Educational Measurement》2019,38(1):48-53
Automatic item generation (AIG)—a means of leveraging technology to create large quantities of items—requires a minimum number of items to offset the sizable upfront investment (i.e., model development and technology deployment) in order to achieve cost savings. In this cost–benefit analysis, we estimated the cost of each step of AIG and manual item writing and applied cost—benefit formulas to calculate the number of items that would have to be produced before the upfront costs of AIG outweigh manual item writing costs in the context of K‐12 mathematics items. Results indicated that AIG is more cost‐effective than manual item writing when developing, at a minimum, 173 to 247 items within one fine‐grained content area (e.g., fourth‐ through seventh‐grade area of figures). The article concludes with a discussion of implications for test developers and the nonmonetary tradeoffs involved in AIG. 相似文献
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It is known that the Rasch model is a special two-level hierarchical generalized linear model (HGLM). This article demonstrates that the many-faceted Rasch model (MFRM) is also a special case of the two-level HGLM, with a random intercept representing examinee ability on a test, and fixed effects for the test items, judges, and possibly other facets. This perspective suggests useful modeling extensions of the MFRM. For example, in the HGLM framework it is possible to model random effects for items and judges in order to assess their stability across examinees. The MFRM can also be extended so that item difficulty and judge severity are modeled as functions of examinee characteristics (covariates), for the purposes of detecting differential item functioning and differential rater functioning. Practical illustrations of the HGLM are presented through the analysis of simulated and real judge-mediated data sets involving ordinal responses. 相似文献
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多面Rasch模型在主观题评分培训中的应用 总被引：7，自引：2，他引：7
主观题的评分受到很多因素的影响,如评分者的知识水平、综合能力和个人偏好等。这些评分者偏差不仅会导致不同评分者之间存在主观差异,也会到导致同一评分者在不同的时间也具有主观不稳定性,最终导致主观题评分信度的降低。本研究将多面Rasch模型运用到某国家级考试论述题的评分培训中。通过分析6名有经验评分者对58份试卷的试评数据,鉴别出四种评分者偏差,然后据此对每个评分者进行个别反馈,从而提高评分的客观性和精确性。 相似文献
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早期的单维IRT模型忽视了测验多维性的可能,而多维IRT模型对各维度的划分不够明确,不能很好地反映各维度能力的内涵。高阶IRT模型承认测验的多维性,以分测验划分维度,同时又将多个维度的能力统一到一个高阶的能力中,能够在了解被试各维度的能力同时,为被试提供整体的能力估计,它能更好地反映实际,并且适应大规模测验的需求。 相似文献
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The Science Teacher Efficacy Belief Instrument has been a widely reported measure of teachers' personal efficacy and outcome efficacy beliefs. This pilot study examined if the instrument could be amended for use in The Arts learning area. A small cohort of 110 Graduate Diploma of Education preservice teachers participated in the pilot. Factor structures were examined through confirmatory factor analyses. The model displaying best fit consisted of six items measuring outcome expectancy and 10 items related to teaching efficacy. Measuring self-efficacy is important as many teachers who teach the Arts in Australia and internationally are not subject specialist teachers. 相似文献
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The purpose of this study is to introduce and evaluate a method for generating reading comprehension items using template-based automatic item generation. To begin, we describe a new model for generating reading comprehension items called the text analysis cognitive model assessing inferential skills across different reading passages. Next, the text analysis cognitive model is used to generate reading comprehension items where examinees are required to read a passage and identify the irrelevant sentence. The sentences for the generated passages were created using OpenAI GPT-3.5. Finally, the quality of the generated items was evaluated. The generated items were reviewed by three subject-matter experts. The generated items were also administered to a sample of 1,607 Grade-8 students. The correct options for the generated items produced a similar level of difficulty and yielded strong discrimination power while the incorrect options served as effective distractors. Implications of augmented intelligence for item development are discussed. 相似文献
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To assess item dimensionality, the following two approaches are described and compared: hierarchical generalized linear model (HGLM) and multidimensional item response theory (MIRT) model. Two generating models are used to simulate dichotomous responses to a 17-item test: the unidimensional and compensatory two-dimensional (C2D) models. For C2D data, seven items are modeled to load on the first and second factors, θ1 and θ2 , with the remaining 10 items modeled unidimensionally emulating a mathematics test with seven items requiring an additional reading ability dimension. For both types of generated data, the multidimensionality of item responses is investigated using HGLM and MIRT. Comparison of HGLM and MIRT's results are possible through a transformation of items' difficulty estimates into probabilities of a correct response for a hypothetical examinee at the mean on θ and θ2 . HGLM and MIRT performed similarly. The benefits of HGLM for item dimensionality analyses are discussed. 相似文献
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计算机自适应性测试中的连续概率比例试模式,是一种适用于普通教师利用网络技术在班级教学这样的小规模测试中评估学生语言学习效果的测试模式。其基本原理就是估计被试连续测试时答对与答错的概率,然后与“掌握”和“未掌握”两个相互对立的假设作比较而产生相应的决策。它一方面可以弥补基于IRT测试模式应用范围的不足,_另一方面可以更好地帮助教师完成对于学生语言能力的评估。 相似文献
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Item response theory scalings were conducted for six tests with mixed item formats. These tests differed in their proportions of constructed response (c.r.) and multiple choice (m.c.) items and in overall difficulty. The scalings included those based on scores for the c.r. items that had maintained the number of levels as the item rubrics, either produced from single ratings or multiple ratings that were averaged and rounded to the nearest integer, as well as scalings for a single form of c.r. items obtained by summing multiple ratings. A one-parameter (IPPC) or two-parameter (2PPC) partial credit model was used for the c.r. items and the one-parameter logistic (IPL) or three-parameter logistic (3PL) model for the m.c. items, ltem fit was substantially worse with the combination IPL/IPPC model than the 3PL/2PPC model due to the former's restrictive assumptions that there would be no guessing on the m.c. items and equal item discrimination across items and item types. The presence of varying item discriminations resulted in the IPL/IPPC model producing estimates of item information that could be spuriously inflated for c.r. items that had three or more score levels. Information for some items with summed ratings were usually overestimated by 300% or more for the IPL/IPPC model. These inflated information values resulted in under-estbnated standard errors of ability estimates. The constraints posed by the restricted model suggests limitations on the testing contexts in which the IPL/IPPC model can be accurately applied. 相似文献