基于SOLIDWORKS电加热器三维建模与数值分析

分析了电加热器的结构特点与SolidWorks软件的三维建模步骤。在几何模型上直接定义了载荷和边界条件,对电加热器温度场与速度场进行了模拟,模拟结果与工程实际吻合较好。探索了有无折流板对电加热器换热的影响,结果显示无折流板的出口温度高于有折流板情况,这对电加热管不利,局部温度过高,长时间工作,容易导致电加热管烧坏。可见利用SolidWorks软件可为电加热器的结构优化与换热等性能的研究提供新的设计手段。     

高职数学教学改革的探讨

高职数学教学的改革成功与否将极大影响学生学习的效果,本文主要介绍山东商业职业技术学院的高等数学教学改革的过程以及结果,提供一些现实中非常实用的方法以及模式,例如反复记忆模式、利用数学建模引发学生兴趣等.期望促进高职数学教学改革的成功.     

ArtCAM相对于数控雕铣加工技术的实际应用

ArtCAM软件可以通过矢量图和各种形式的位图文件建立复杂的三维立体浮雕造型,并可以生成复杂的刀具轨迹。将ArtCAM与数控雕铣加工技术有机结合,充分实现数控设备的较强加工功能,促进CAD/CAM技术在雕铣加工中的广泛应用。     

数学模型与数学实验教学改革探索

数学模型与数学实验教学如何适应现代数学科学的迅猛发展,满足社会对高素质数学人才的需求,是高等理工科院校共同面临的课题。从教学观念的改变、教学内容的更新、教学模式的优化以及教学考核机制的完善等方面进行研讨,主旨在为数学模型与数学实验教学改革探索有效的解决途径。     

Coupled matrix factorization and topic modeling for aspect mining

Aspect mining, which aims to extract ad hoc aspects from online reviews and predict rating or opinion on each aspect, can satisfy the personalized needs for evaluation of specific aspect on product quality. Recently, with the increase of related research, how to effectively integrate rating and review information has become the key issue for addressing this problem. Considering that matrix factorization is an effective tool for rating prediction and topic modeling is widely used for review processing, it is a natural idea to combine matrix factorization and topic modeling for aspect mining (or called aspect rating prediction). However, this idea faces several challenges on how to address suitable sharing factors, scale mismatch, and dependency relation of rating and review information. In this paper, we propose a novel model to effectively integrate Matrix factorization and Topic modeling for Aspect rating prediction (MaToAsp). To overcome the above challenges and ensure the performance, MaToAsp employs items as the sharing factors to combine matrix factorization and topic modeling, and introduces an interpretive preference probability to eliminate scale mismatch. In the hybrid model, we establish a dependency relation from ratings to sentiment terms in phrases. The experiments on two real datasets including Chinese Dianping and English Tripadvisor prove that MaToAsp not only obtains reasonable aspect identification but also achieves the best aspect rating prediction performance, compared to recent representative baselines.     

Spark作业性能建模及参数优化

Apache Spark分布式大数据计算框架应用广泛,但是其配置参数繁多导致使用难度较大,且不合理的配置将严重影响作业执行性能,研究Spark参数对性能的影响并进一步对参数进行自动优化具有重要意义.该文分析了 Spark作业中影响系统行为的关键参数,建立了性能模型,并进一步探索了 Spark参数自动优化的方法和策略.通...     

企业组织结构的刚性特征及对战略变革的影响

刚性是指企业组织结构极端理性的特征,并会影响到战略变革。把该特征分为五个维度：正式化、集权化、整合化、复杂化与制度化,并以中国企业为样本进行实证分析。结果发现,正式化与复杂化维度对战略变革具有阻碍作用。更重要的是,制度化维度对战略变革具有正向推动作用,这与西方学者的众多研究结论是相反的。     

非理想反激变换器连续工作模式建模分析

基于电路平均法,同时考虑实际变压器、二极管、电容、MOSFET管寄生参数的影响,在连续工作模式下建立非理想反激变换器直流和小信号模型,并推导出传递函数．模型分析以及仿真结果证实所建模型能够准确地反映变换器的实际特性．     

Clones identification of Sequoia sempervirens (D. Don) Endl. in Chile by using PCR-RAPDs technique

A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied. The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction. The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index and a dendrogram was constructed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA). Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of 49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although they are derived from the same geographic origin. Project (No. CONICYT-FONDEF PROYECT D01 I 1008) supported by the National Commission of Science and Research of Chile     

分子标记及其在甘薯种质资源和遗传育种中的应用

植物分子生物学和植物生物技术利用分子标记技术得到了大力发展,分子标记的创新、发展与应用对其起了积极的推动作用,本文就RFLP、AFLP、RAPD、DAF、SSR、CAPS分子标记的原理与技术及其在甘薯种质资源和遗传育种中的应用作一介绍