A general version of the Morse-Sard theorem

INTRODUCTION The Morse-Sard theorem is a fundamentaltheorem in analysis, especially in the basis oftransversality theory and differential topology. Theclassical Morse-Sard theorem states that the imageof the set of critical points of a function f: Rm→Rnof class Cm ?n 1 has zero Lebesgue measure in Rn. Itwas proved by Morse (1939) in the case n =1andby Sard (1942) in general case. So it is called. Due to its theoretical importance, the Morse-Sard theorem was generalize…     

优秀译文

During the Beijing Olympic Games, t was witnessed that Chinese athlets put on a successful performance and broke many records.Meanwhile, it was the same as the past Games that there were many great pities we have to keep in mind. Because of the hated competition of athletics, the Games took on the performance of perfection, as well as greatness of Pity. In a sense, the pity is one of the indispensable attractions of athletics.Actually, it is the pity that allows us to fully appreciate what a successful life is,     

完形填空精练(英文)

As the pace of life continues to increase,we are fast losing the art of relaxation.1you are in thehabit of rushing through life,being on the go from morningtill night,it is hard to2down.But relaxationis3for a healthy mind and body.Stress is a4part of everydaylife and there is no way to5it.Infact,it is not the bad thing that it is oftensupposed to be.A6amount of stressis important to provide motivation and give7to life.It is only when the stressgets out of control8it can lead topoor performanc…     

Constant-step stress accelerated life test of VFD under Weibull distribution case

Constant-step stress accelerated life test of Vacuum Fluorescent Display (VFD) was conducted with increased cathode temperature. Statistical analysis was done by applying Weibull distribution for describing the life, and Least Square Method (LSM) for estimating Weibull parameters. Self-designed special software was used to predict the VFD life. Numerical results showed that the average life of VFD is over 30000 h, that the VFD life follows Weibull distribution, and that the life-stress relationship satisfies linear Arrhenius equation completely. Accurate calculation of the key parameter enabled rapid estimation of VFD life.     

Idealism and Reality,history and poem:The Journey as Polyphonic Form in History of the Soul

In the present paper the approach of formalism was adopted to analyze Zhang Chengzhi’ s work History of the Soul.According to the analysis to its form selection,unique style,the speaker’ s voice and the symbol,it is proved that a proper form and literary experience function to each other.And a conclusion was drawn that this work both contains a fantasy in reality and a reality in history.It is a journey of the author’ s soul,a real fiction.     

Application of time-temperature superposition method in thermal aging life prediction of shipboard cables

The life of shipboard cables will decrease due to the complex aging processes. In terms of the safety perspective, remaining life prediction of the cable is essential to maintain a reliable operation. In this paper, firstly, based on Arrhenius equation, residual life of new styrene-butadiene cable is calculated; result indicates that the degradation rate which changes with time is proportional to thermal temperature. Then second order dynamic model is adopted into the residual life prediction, combined with the time-temperature superposition method （TTSP）, and a new residual life model is proposed. According to the accelerated thermal aging experiment data and Arrhenius equation, TTSP method demonstrates to be an efficient way for life prediction, and life at normal temperature can be estimated by this model. In order to monitor the state of styrene-butadiene cable more accurately, an improved residual life model based on equivalent environment temperature of cable is proposed, and life of cable under real operation is analyzed. Result indicates that this model is credible and reliable, and it provides an important theoretical base for residual life of cables.     

Naturalistic Elements in The Egg

The purpose of the study is to analyze the naturalistic elements in The Egg, which is taken from the collection of short stories, The Triumph of the Egg. The study states the ideology and technique of naturalism and then exams how naturalistic elements are revealed in the fiction. Then it comes to the conclusion that the family is defeated by the egg and the life of human beings is under control of complicated forces from both inside and outside.     

High cycle fatigue life prediction and reliability analysis of aeroengine blades

Based on the nonlinear continuum damage model(CDM) developed by Chaboche,a modified model for high cycle fatigue of TC4 alloy was proposed.Unsymmetrical cycle fatigue tests were conducted on rod specimens at room temperature.Then the material parameters needed in the CDM were obtained by the fatigue tests,and the stress distribution of the specimen was calculated by FE method.Compared with the linear damage model(LDM),the damage results and the life prediction of the CDM show a better agreement with the test and they are more precise than the LDM.By applying the CDM developed in this study to the life prediction of aeroengine blades,it is concluded that the root is the most dangerous region of the whole blade and the shortest life is 58 211 cycles.Finally,the Cox proportional hazard model of survival analysis was applied to the analysis of the fatigue reliability.The Cox model takes the covariates into consideration,which include diameter,weight,mean stress and tensile strength.The result shows that the mean stress is the only factor that accelerates the fracture process.     

混凝土三轴等幅拉-压疲劳性能试验研究

Fatigue tests were conducted on tapered plain concrete prism specimens under triaxial constant-amplitude tension-compression cyclic loading. The low stress of the cyclic loading was taken as 0.2fc and the upper stress ranged from 0.20ft to 0.65ft. Three constant lateral pressures were 0.1fc, 0.2fc and 0.3fc respectively. Based on the results, the three-stage evolution nile of the fatigue stiffness, maximttm(minimum) longitudinal strain and damage were analyzed, and a unified S-N curve to calculate fatigue strength factors was worked out. The results show that the fatigue strength and fatigue life under triaxial constant-amplitude tension-compression cyclic loading are smaller than those under uniaxial fatigue condition. Moreover, the secondary strain creep rate is related to the fatigue life, a formula for describing their relation was derived. The investigation of this paper can provide information for the fatigue design of concrete structures.     

Flexural rigidity evolvement laws of reinforced concrete beams strengthened with carbon fiber laminates

Extensive research has shown that externally bonded carbon fiber reinforced polymer (CFRP) laminates are particularly suitable for improving the fatigue behavior of reinforced concrete (RC) beams. This paper presents the research on flexural rigidity evolvement laws by testing 14 simple-supported RC beams strengthened with carbon fiber laminates (CFL) under cyclic load, and 2 under monotone load as a reference. The cyclic load tests revealed the peak load applied onto the surface of a supported RC beam strengthened with CFL is linear to the logarithm of its fatigue life, and the flexural rigidity evolvement undergoes three distinct phases: a rapid decrease from the start to about 5% of the fatigue life; an even development from 5% to about 99% of the fatigue life; and a succedent rapid decrease to failure. When the ratio of fatigue cycles to the fatigue life is within 0.05 to 0.99, the flexural rigidity varies linearly with the ratio. The peak load does not affect the flexural rigidity evolvement if it is not high enough to make the main reinforcements yield. The dependences of the flexural rigidity of specimens formed in the same group upon their fatigue cycles normalized by fatigue life are almost coincident. This implies the flexural rigidity may be a material parameter independent of the stress level. These relationships of flexural rigidity to fatigue cycles, and fatigue life may be able to provide some hints for fatigue design and fatigue life evaluation of RC member strengthened with CFL; nevertheless the findings still need verifying by more experiments.     

NBEE和NWEE寿命分布类及其性质(英文)

在比较寿命 X 与其平衡寿命 Xe 的数学期望的基础上,研究了一类新的寿命分布类 NBEE 和它的对偶类NWEE. 讨论了 NBEE(NWEE) 与其他寿命分布类的关系,证明了 NBEE 分布类是一种很大的分布类,IFR,NBU,L 类等为它的子类. 分析了 NBEE(NWEE) 在卷积、混合等可靠性运算下的封闭性质. 针对泊松冲击模型和累积失效模型,分别给出了系统寿命属于 NBEE(NWEE) 类的充要条件. 在齐次泊松冲击模型中,系统寿命属于 NBEE(NWEE) 类的充要条件是离散冲击失效分布属于 DNBEE(DNWEE) 类. 而在累积失效模型中系统中,累积失效寿命属于 DNBEE 类的充要条件是损失量阈值的分布属于 NBEE 类.     

Frame 分离公理(英文)

在Ｆｒａｍｅ理论中,与拓扑空间中的Ｈａｕｓｄｏｒｆ分离公理相对应的分离公理已被较深入地研究,但其结果并不很理想．本文给出相对应于Ｈａｕｓｄｏｒｆ分离公理的另一种定义,称之为分离公理．并证明如把此分离公理应用于Ｓｐａ－ｔｉａｌｆｒａｍｅｓ－拓扑－之上,它将与Ｈａｕｓｄｏｒｆ分离公理完全等价,而且此分离公理对于Ｓｕｂｆｒａｍｅｓ以及Ｆｒａｍｅ的和运算有遗传性．同时进一步证明：由满足此分离公理的ｆｒａｍｅｓ组成的范畴ＦＲＡＭＥ与Ｈａｕｓｄｏｒｆ拓扑空间范畴ＴＯＰ是反变伴随的．     

Lower Secondary Students’ Views in Astrobiology

Astrobiology is, on a profound level, about whether life exists outside of the planet Earth. The question of existence of life elsewhere in the universe has been of interest to many societies throughout history. Recently, the research area of astrobiology has grown at a fast rate, mainly due to the development of observational methods, and the media is frequently reporting on new research findings. International surveys show that astrobiology questions are among those that interest young people the most. The popularity of astrobiology and the way it captures much science content makes it an interesting area for science teaching. However, there is very little research directly focused upon students’ views in astrobiology. The study reported in this paper draws from the answers of 186 Swedish lower secondary students (16 years old) to a questionnaire, with closed and open-ended questions regarding their views of issues in astrobiology. The study was guided by the worldview theory (Cobern 1991; Cobern, Science Education 80(5):579–610, 1996; Cobern, Science and Education 9:219–246, 2000). The results show that even though basic reasoning in astrobiology is known by a majority of the students, there is a considerable number of students, for whom this is not the case. Furthermore, it was found that for all questions, there are students answering in different ways when asked to describe their own view and the view they associate with science researchers. The implications of the study for further research and for the teaching of astrobiology in science class are discussed.     

三对角逆M-矩阵性质的探讨

本文研究一类特殊的逆M-矩阵:三对角逆M-矩阵.用图论的方法完全刻划了三对角逆M-矩阵的结构特征和性质,给出了三对角非负矩阵是逆M-矩阵的充要条件.最后,证明了具有唯一路M-矩阵的逆在Hadamard乘积下的封闭性.     

分次模态传递框架类

本文证明分次模态逻辑在有穷传递框架类中的Goldblatt-Thomason定理.一个有穷传递框架类可由分次模态公式集定义当且仅当它在不相交并、生成子框架和分次有界态射像下封闭.该定理的证明使用带根的有穷传递框架的分次Jankov-Fine公式.     

Growth Mixture Modeling With Nonnormal Distributions: Implications for Data Transformation

This study investigated the extent to which class-specific parameter estimates are biased by the within-class normality assumption in nonnormal growth mixture modeling (GMM). Monte Carlo simulations for nonnormal GMM were conducted to analyze and compare two strategies for obtaining unbiased parameter estimates: relaxing the within-class normality assumption and using data transformation on repeated measures. Based on unconditional GMM with two latent trajectories, data were generated under different sample sizes (300, 800, and 1500), skewness (0.7, 1.2, and 1.6) and kurtosis (2 and 4) of outcomes, numbers of time points (4 and 8), and class proportions (0.5:0.5 and 0.25:0.75). Of the four distributions, it was found that skew-t GMM had the highest accuracy in terms of parameter estimation. In GMM based on data transformations, the adjusted logarithmic method was more effective in obtaining unbiased parameter estimates than the use of van der Waerden quantile normal scores. Even though adjusted logarithmic transformation in nonnormal GMM reduced computation time, skew-t GMM produced much more accurate estimation and was more robust over a range of simulation conditions. This study is significant in that it considers different levels of kurtosis and class proportions, which has not been investigated in depth in previous studies. The present study is also meaningful in that investigated the applicability of data transformation to nonnormal GMM.     

封闭空间环境控制理论与哲学思想

封闭环境与封闭环境控制技术（如建筑空间、飞机空间、工业低温空间）是指人工创造的,为人类生产生活服务的技术,其在现代社会中有不可替代的地位。舒适、节能、环保、健康的封闭环控技术只有在正确的哲学观念引领下才有可能实现人、外部环境、环控系统、封闭环境的和谐统一。天人和谐,以人为本,承认大自然的内在价值,认识自然美等哲学观念可以有效指导封闭环控技术的概念设计。在分析封闭空间环控,基本自然哲学观基础上,总结了同封闭空间环控有关的哲学思想,思想核心是天人统一。     

简论《实践论》对中国知识分子自由的影响

《实践论》使中分国知识子得到了新生，实现了自由。但在特定环境下又让这一阶层的人们陷入困境而难以自由。毋庸置疑，中国知识分子的如此境遇只能是历史的匆匆过客，它最终会通过否定之否定而使中国知识分子获得更高的自由。     

荒原的精灵之歌--从艾米莉的性格看《呼啸山庄》的主题

艾米莉出身于牧师家庭,富于才华,有良好的教养;但她生活在较闭塞而生硬的环境里,接受着简单、古板的教育,因而性格内向。这使她难以适应社会,生活封闭,经历简单,对人生充满痛感;精神上“反叛社会”,幻想超现实的自由生活(“返回自然”)。《呼啸山庄》正是艾米莉上述人生状态与精神的自传,客观上具有超越时空的人类启示意义。     

鲁棒自适应飞行跟踪控制系统设计

针对具有外部扰动的一类非线性飞行控制系统提出了一种在线神经网络控制的方法,应用3个在线神经网络分别实时抵消系统中的非线性部分、与控制量耦合的非线性项以及外部扰动,使受控系统的输出可以完全跟踪给定输入参考信号。文中以一个实际的验证机非线性模型为仿真对象,验证了这种方法的有效性,由于在线神经网络的动态补偿特性,即使飞机在不同的高度和速度下,在模型参数发生改变时,控制过程并不需要改变增益表就可以完成全包络的飞行跟踪控制,相关的定理证明了整个神经自适应飞行闭环控制系统的稳定性,仿真示例表明了该设计方法的有效性。