C中易出错的若干问题

分析了C语言编程中存在的若干问题 ,并指明了原因 ,给出了解决方法。     

Complementary Relationships Between Traditional Media and Health Apps Among American College Students

Abstract

Objective: This study explored the potential relationships between existing media and health apps for health information among college students. Participants: This study collected and analyzed a total of 408 surveys from students of 7 universities across the United States. Methods: In order to explore the research questions and test the hypotheses, quantitative data from the online survey were analyzed through hierarchical regression analyses. Results: Results from the hierarchical regression analyses indicated that the perceived credibility of health information from traditional mass media was positively and significantly associated with college students' perception of health apps. However, there was no significant effect in regards to online media. Conclusions: This study's consideration of the relationships between existing media and health apps may guide health practitioners in their strategic approaches to improve the well-being of college students.     

阎若璩与汪琬礼学论争考述

阎若璩、汪琬为清初经学的代表人物。二人在康熙年间的礼学之争始于金石义例之辩,焦点集中在礼服学上,是清代礼学史上的第一次大论争。二人礼学观不同,研经治礼方法互异。汪琬兼采汉、宋之学,重求本义,主于律文以求"用实",不屑专事章句之学;阎若璩倡古礼以兴"古学",取法汉儒,重于考据训诂,排斥宋学,批评自朱子以来学者不事考据以致"私造典礼"之习。这场论争体现了清初礼学复兴时期的特征,对清代礼学发轫有着深远的意义。     

屈原生辰研究综述

屈原是中国历史上第一个伟大诗人,他创作的楚辞体文学开创了中国文学的另一个源头。由于朝代邈远,战乱频仍,使很多关于屈原的珍贵史料荡然无存,因此,对这样一位重要的作家,关于其生平的材料却只有一鳞半爪,使后世的研究者对其人其作争论不休,至今未有定论。关于其生辰的争论一直是个焦点,自王逸,朱熹各自提出关于屈原出生日期的观点以来,关于屈原生辰的研究便没有停止过,特别是近代,更是对屈原的生辰进行前所未有的实证性研究。本文尽量穷尽关于屈原生辰的研究成果,以期能给后来研究者提供这一论题的研究全貌。     

线性规划中的灵敏度分析

考虑了线性规划模型中的灵敏度分析，解决了当约束条件减少时，最优解如何变化的问题。     

Standard Errors for Elasticities: A Comparison of Bootstrap and Asymptotic Standard Errors

This article compares two methods of deriving standard errors for elasticities in a linear expenditure demand system with first-order autoregressive errors. The first is the ordinary Taylor series method and the second is Efron's bootstrap. In an example problem, these two methods yielded similar values for the standard errors, with the exception of the income elasticity standard errors, for which the asymptotic standard errors were apparently too large by a factor of two.     

How to Teach by the Unit Method

Using data from the National Center for Educational Statistics research spanning fifteen years, researchers examined the impact of national educational policy implementation on the role of social studies in elementary schools. Specifically, with the reauthorization of No Child Left Behind (NCLB) in 2007 and the continuation of federal-mandated testing of English language arts (ELA) and mathematics in grades three through five, researchers sought to understand how policy decisions to extend testing to science affected teacher decisions in regard to instructional time allocations for core subject areas of ELA, mathematics, science, and social studies in elementary schools. Results of this quantitative study offer large-scale evidence of the declining role of social studies in an era in which testing is clearly linked to subject-area importance. Findings provide an overview of the national scope of testing and the ramifications for social studies in elementary schools. Researchers conclude that curriculum standardization, accountability, and high-stakes testing have had adverse affects on social studies time allotments in comparison to tested subjects.     

Quantitative Risk Assessment of the New York State Operated West Valley Radioactive Waste Disposal Area

This article is based on a quantitative risk assessment (QRA) that was performed on a radioactive waste disposal area within the Western New York Nuclear Service Center in western New York State. The QRA results were instrumental in the decision by the New York State Energy Research and Development Authority to support a strategy of in‐place management of the disposal area for another decade. The QRA methodology adopted for this first of a kind application was a scenario‐based approach in the framework of the triplet definition of risk (scenarios, likelihoods, consequences). The measure of risk is the frequency of occurrence of different levels of radiation dose to humans at prescribed locations. The risk from each scenario is determined by (1) the frequency of disruptive events or natural processes that cause a release of radioactive materials from the disposal area; (2) the physical form, quantity, and radionuclide content of the material that is released during each scenario; (3) distribution, dilution, and deposition of the released materials throughout the environment surrounding the disposal area; and (4) public exposure to the distributed material and the accumulated radiation dose from that exposure. The risks of the individual scenarios are assembled into a representation of the risk from the disposal area. In addition to quantifying the total risk to the public, the analysis ranks the importance of each contributing scenario, which facilitates taking corrective actions and implementing effective risk management. Perhaps most importantly, quantification of the uncertainties is an intrinsic part of the risk results. This approach to safety analysis has demonstrated many advantages of applying QRA principles to assessing the risk of facilities involving hazardous materials.     

The effects of correlation among observations on the consistency property of sample variance

It is well known that even when the sample observations are correlated and not normal the sample variance, S² converges in probability to E(S²). But the required sample size for S² to be a consistent estimator of E(S²) is an open question. Some light is shed on this question in this paper. In particular the relation between the rate of convergence and the correlation property of the observations is explored. It is shown that the retardation to the rate of convergence is not appreciable if the correlation is moderate but it can be severe for extreme correlations.     

软件无线电中正交数字变频的DSP实现

介绍了软件无线电的概念及DSP基本原理,利用DSP实现软件无线电中的正交数字变频技术,给出了中频下变频的数字化实现的主程序.