有关数学期望计算的一个典型错误

对条件期望与无条件期望混淆不分,是计算二维随机变量函数数学期望时常犯的典型错误之一,结合实例分析,指出合理利用随机变量函数数学期望的定义或全概率公式,可避免此类错误的产生.     

有关数学期望的优化问题

讨论随机变量函数的数学期望的求解及其应用问题.针对连续型和离散型随机变量,实例说明有关数学期望的一类随机优化模型的决策变量的求解问题,指出在离散情形下相关问题的传统解法容易漏解,并给予修正.     

运用因子分析评估教学质量

文章通过教师所授学科成绩进行SPSS软件的因子分析,给出各位任课教师在考试前一段时间内的教学质量评估.此方法比单纯用数学期望和方差分析更有说服力,此操作简单.     

探究式教学模式在职业中专数学教学中的应用研究

中专数学探究式教学模式的研究目的,在于改革传统的教学模式,优化教学效果,提高教学质量.本文对探究式教学模式及数学探究式教学模式等有关理论进行了介绍,重点探讨了探究式教学模式在职业中专数学教学中的应用策略,期望可以为中专数学教学工作带来一些新的思路与借鉴.     

切比雪夫不等式证明的启示及应用

通过对切比雪夫不等式的证明,得到含数学期望和方差的概率不等式的证法.阐述了切比雪夫不等式是证明切比雪夫大数定律的重要工具和理论基础,在概率论及其实际生活中有很多应用.     

配料问题优化算法的数据分析与评价

针对铜闪速熔炼配料优化问题,简单介绍了一种配料优化算法。通过与另一种优化算法作多次重复计算数据对比,用正态分布、数学期望和标准方差统计学知识客观地分析和评价了这种算法。     

在小学数学教学中如何进行自主记忆的培养

在小学数学教学中,笔者经过长时间的观察,对比,思考,发现小学数学课堂教学效果并不尽人意,与所期望的相去甚远,究其因为学生学习缺乏学习内化的手段--自主记忆,没有记忆是不行的,尤其是自主记忆,没有强力自主记忆就没有了进一步学习的基础,短时记忆或者无意记忆都是不能有效地成就高效学习,因此把记忆变为自主状态是刻不容缓的.     

x2分布数学期望和方差的推导

从x2分布的定义出发,根据期望、方差的计算和性质,利用标准正态分布的期望、方差的性质,用广义积分和分布积分的计算方法,推导了x2分布的期望和方差.     

浅谈英语教学中的期望教育

结合教学实践,介绍了英语期望教育的应用方法及效果,并提出了期望教育中应注意的问题。     

数学建模思想融入《数学分析》教学

数学素质和创新能力是现代数学教育的目标,将数学建模的思想方法融入<数学分析>教学,从教学的主要环节提出了渗透数学建模思想方法的一些方法和实践.     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

显微维氏硬度测量不确定度评定

对显微维氏硬度测量不确定度进行评定，建立了不确定度计算的数学模型，确定了影响实验结果的各项因素，计算出了各因素的标准不确定度，得出结果的扩展不确定度，并给出最终测量结果的表达式。     

Concept of freedom of infection of animal flocks

Totally negative results of epidemiological investigation of random samples do not prove the absence of the infection as the pathogen may be restricted to only a few animals in the herd for a long time. The statement "absence of infection" is critical for such situations. The question is raised, whether the statement "absence of infection" should be generally avoided. Classification of herds and flocks according to the prevalence of the pathogen would be more valid for the implementation of control measures.     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.