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结合2012年数学建模大赛的酿酒葡萄等级划分案例,对酿酒葡萄分级问题进行分析,建立相应的数学模型,阐述了数学建模中的聚类分析法在实际问题中的应用过程及模型求解方案,同时对整体模型进行了评价,并提出了相应的改进意见. 相似文献
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提出了在同时考虑酿酒葡萄和葡萄酒的情况下,运用多目标优化模型研究酿酒葡萄的分级方法.首先,建立了以酿酒葡萄的各个理化指标的误差平方和最小和酿酒葡萄对应的葡萄酒质量误差平方和最小为目标的多目标0-1规划模型;其次,利用线性加权法,将多目标0-1规划模型转化成单目标0-1规划模型;然后,建立基于酿酒葡萄分类结果的酿酒葡萄分级模型;最后,将该模型运用于酿酒葡萄分级问题中,将酿酒葡萄分成5级,每级个数分别为6,5,4,6,6,避免了分级方法的主观性和分级不均匀性. 相似文献
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酿酒葡萄叶面积的测定方法研究 总被引:14,自引:1,他引:14
在调查酿酒葡萄叶片形状及大小的基础上,以两年、两个试验地点的3个酿酒葡萄品种(赤霞珠、梅鹿辄、阿尔卡布斯)的成熟叶片为试材,应用相关的回归分析,找出叶片宽度(x)和叶面积(y)的回归方程。结果表明:两个试验地点的相同品种(赤霞珠)以及两个试验地点的3个不同品种的混合叶片,均可以用叶宽做自变量,建立与叶面积的回归方程,并且相关程度达极显著水平。这为酿酒葡萄叶面积的测定提供了一个更为简单0实用、操作快捷的测定方法。 相似文献
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采用摘心,去副梢,去叶等进行组合处理研究了雷司令品种的反季果酿酒特性。结果表明:不同处理的反季节结果能力有显著差异;冬芽成花结实率高于夏芽;摘心+去副梢处理的效果优于不摘心+去副梢处理。 相似文献
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昌黎县酿酒葡萄产业化存在问题与对策研究 总被引:1,自引:0,他引:1
李育华 《河北职业技术师范学院学报》2002,16(2):52-56,67
通过对昌黎县酿酒葡萄产业化现状及存在问题的分析,认为葡萄产业化可持续发展的关键是:提高葡萄和葡萄酒的质量;建立利益分配机制和开拓市场,并对此提出了一些具体措施。 相似文献
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为提高萧县酿酒葡萄残渣的利用率,采用索氏提取法,以石油醚为溶剂,从酿酒葡萄残渣中提取植物油,利用气相色谱-质谱联用探究植物油中脂肪酸组成及含量。以酸价和过氧化值为依据,探究温度、水分、氧气、金属离子、抗氧化剂对植物油氧化稳定性的影响。结果表明,石油醚对酿酒葡萄残渣中植物油的提取率为(22.01±0.78)%,其中含有21种脂肪酸,包括三种必需脂肪酸:亚油酸(42.67%)、α-亚麻酸(7.11%)、花生四烯酸(0.10%),不饱和脂肪酸总量高于饱和脂肪酸。温度、水分、氧气、金属离子均会在一定程度上影响酿酒葡萄残渣中植物油的氧化稳定性,而加入一定量的抗氧化剂可抑制其氧化酸败,其中没食子酸丙酯的效果最好。 相似文献
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《黄冈职业技术学院学报》2017,(4):103-108
随着市场经济的发展,人们的生活水平不断提高,酒类消费占总消费支出比例逐年增加,酿酒行业日益兴盛,酒文化已渗透到人们生活中的方方面面,并推动着我国GDP的增长。因此,研究酿酒行业上市公司综合绩效势在必行。本文选取了我国酿酒行业30家上市公司作为研究对象,基于其2015年财务报告,利用因子分析法进行综合绩效评价,以期为公司管理人员、投资者们提供决策建议。 相似文献
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沃尔评分法指标体系的探索与改进 总被引:1,自引:0,他引:1
危高潮 《荆门职业技术学院学报》2009,24(12):66-71
文章结合统计学原理运用应用回归分析的方法,对沃尔评分法指标体系的指标选取,以及指标的比重进行了探索。分别从沃尔指标体系指标选择的代表性、独立性、可操作性出发,探索了沃尔评分法指标体系的科学性,发现沃尔指标体系指标选择不尽合理,提出了改进方法。 相似文献
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扩招形势下的英语分级教学 总被引:1,自引:0,他引:1
阮先凤 《海南师范大学学报(社会科学版)》2004,17(6):97-99
近几年高校不断的扩招,推动了高等教育由昔日的“精英教育”向“大众化教育”的转变,但扩招也带来了学生生源分布广、水平参差不齐的新问题。遵循“以人为本”、“以学生为中心”的教学理念,体现因材施教的原则和灵活的教学管理方法的分级教学在一定程度上扭转了教学上的被动局面,大大提高了教学效果。 相似文献
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在高等教育自学考试诸多工作中,评卷工作是一个重要环节,客观、公正、合理地评卷,可以鼓舞鞭策学员积极学习、努力进取,为国家选拔更多的合格人才。本文就自学考试评卷管理工作进行了深入的探讨。 相似文献
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Grades are important for admission of students in most higher education programs. Analyzing admission and student performance data at a major Norwegian business school, we find that the grading practice of teachers at regional colleges sending students to the school is affected by the average performance of the students being graded. Teachers at colleges recruiting good students from upper secondary school tend to be strict in their grading practice, while teachers at colleges recruiting less good students tend to follow a lenient practice. This has implications for the interpretation of grades and hence for optimal admission procedures. We develop a methodology to assess the consequences of differential grading standards. Approximately 10% of the students in our data are admitted at the expense of more competent students. We demonstrate costs for the school admitting the wrong students and in particular for the rejected students. 相似文献
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学业评价是教师教育教学中的重要环节,不仅关系到对学生的评价,也关系到学生对学习的情感态度和努力投入,以及师生关系的质量。优秀的中小学教师在评定学生学业成绩时,能够从学生长远发展角度考虑评价对学生的全面影响,重视评分的发展性评价目的;在具体评分实践中,能充分考虑学生对分数的认识、理解和感受,评分目的明确;能够运用多种评价方式,从多个来源对学生多个方面的表现实施多元综合评价;能够根据评分目的和条件合理恰当地选择评分标准,评分灵活可靠,又不失评价原则。这些理念和策略作法,确保了他们的评分能够真正发挥鼓励学生学习,促进学生成长的广阔而深远的目的。 相似文献
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Grading and the Ethos of Effort 总被引:1,自引:0,他引:1
Using quantitative and qualitative data from a project to improve middle-school girls' engagement with science, mathematics
and technology, this study examined the ways in which grading practices worked to augment the messages about achievement and
compliance conveyed in more and less troubled schools. In particular, the study revealed differences in the extent to which
different kinds of schools embedded achievement and non-achievement factors in the grades awarded to middle school girls.
The study linked these differences to school-level differences in teachers' overall orientation toward grading. Grading in
the more troubled schools - those with a more custodial orientation toward control - appeared to reflect teachers' tendency
to subscribe to an 'ethos of effort'. Acting on the basis of this 'ethos', teachers in the troubled schools tended to confound
achievement and non-achievement factors in the determination of report-card grades. In the less troubled school, by contrast,
teachers did not rely as heavily on non-achievement factors when they determined students' grades. Given limitations associated
with sampling, however, findings from the study were viewed cautiously. Nevertheless, the research appeared to support the
claim that there could be systematic associations between school-level climate characteristics and particular instructional
practices.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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《The Journal of educational research》2012,105(4):203-213
Abstract The authors investigated the assessment and grading practices of over 900 Grades 3-5 teachers representing urban, suburban, and rural schools. Teachers indicated the extent to which they used various factors to grade students, the types of assessments used, the cognitive level of assessments, and the grades awarded. Teachers appeared to conceptualize 6 major factors when they graded students; they placed the greatest weight on academic performance and academic-enabling behaviors, such as effort and improvement, and much less emphasis on homework, comparisons with other students, grade distributions of other teachers, and borderline cases. The teachers used 3 types of assessments—constructed-response, objective, and teacher-made major examinations; they differentiated between recall and higher level cognitive skills. However, there were few relationships between assessment and grade level, subject matter assessed, and grades awarded. Results are discussed in light of other research, indicating that teachers use a “hodgepodge” of factors when assessing and grading students. 相似文献
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二语学习者必须吸收相当的语言输入,但是要达到并增强输入的效果,需要同时重视语言的输出,输出有助于促进二语学习者流利和准确地使用语言;大学英语教学的中级阶段尤其要加强训练学生的输出能力以及输出的有效性;从实验和对比中可以看出,针对大学英语分级教学中不同起点选修三级课程的学生,输出训练要依照相关理论在统一部署下有区别、有针对性地进行,科学合理地组织教学过程,全面考虑教学过程的各个方面,重视学生的差异性,改良教学模式,实现更多学生更多语言的有效输出。 相似文献