二阶导数的几何意义及直观解释     

赵开斌 《巢湖学院学报》2005,7(3):32-34

本文给出抛物线y=ax2 bx c(a≠0)"张口宽度"的一种度量--张口度,此张口度仅与a有关.若y=f(x)在U(x0)内三阶可导,y=f(x)可由f(x)=f(x0) f′(x0)(X-X0) f"(x0)/2!(X-X0)2近似,可得出f"(x0)与f(x)的张口度有关.  相似文献   

大跨钢管混凝土桁架拱桥的地震反应分析     

李少冲  张毅  范存新 《巢湖学院学报》2008,10(6)

以巫峡长江大桥为研究背景,通过建立空间结构有限元模型,计算和分析该大桥的动力特性,并运用时程分析法分析该桥的地震反应,采用EI-centro波进行计算,讨论横桥向和竖桥向地震动对地震反应的影响和规律,为大跨度钢管混凝土拱桥的抗震设计和研究提供了理论依据。  相似文献   

Construction simulation and real-time control for high arch dam   总被引：1，自引：0，他引：1  

钟登华  任炳昱  吴康新 《天津大学学报(英文版)》2008,14(4):248-253

A method of combining dynamic simulation with real-time control was proposed to fit the randomness and uncertainty in the high arch dam construction process. The mathematical logic model of high arch dam construction process was established. By combining dynamic construction simulation with schedule analysis, the process of construction schedule forecasting and analysis based on dynamic simulation was studied. The process of real-time schedule control was constructed and some measures for dynamic adjustment and control of construction schedule were provided. A system developed with the method is utilized in a being constructed hydroelectric project located at the Yellow River in northwest China, which can make the pouring plan of the dam in the next stage (a month, quarter or year) to guide the practical construction. The application result shows that the system provides an effective technical support for the construction and management of the dam. ZHONG Denghua, born in 1963, male, Dr, Prof. Supported by National Natural Science Foundation of China(No.50539120), National Basic Research Program of China(“973”Program,No. 2007 CB714101), National Science Fund for Distinguished Young Scholars of China(No.50525927), and National Natural Science Foundation of China (No.50579045).  相似文献   

Mapping students' interest in a new domain: Connecting prior knowledge,interest, and self-efficacy with interesting tasks and a lasting desire to reengage     

《Learning and Instruction》2021

How students experience educational environments and the interconnections between their readiness, task experiences and their long-term desire to reengage with course content are critical questions for educators. Research postgraduate students (n = 310) at a research-intensive university in Hong Kong, engaging in a 24-h introductory teaching course, participated in this study. Learner readiness for the course was assessed as prior Domain interest, self-efficacy, and knowledge. Subsequently, students completed four formative assessments, reported their on-task interest in seven strategically chosen tasks and end-of-course Course and Domain interest. Longitudinal-SEM tested interconnections between readiness components, Task, Course and Domain interest. Initial self-efficacy beliefs for teaching predicted early Task interest, while Domain interest was a predictor of Task interest in explicitly practical task experiences. Strong interconnections between Task interest across the study were evident. Individual written and social discussion tasks presented strong contributions to future Course/Domain interest. Implications for theory and practice are discussed.  相似文献   

An empirical investigation of information sharing behavior on social commerce sites     

《International Journal of Information Management》2016,36(5):686-699

Social commerce sites (SCSs), a new model of social media, provide fertile ground for customers to communicate their opinions and exchange product- or service- related information. Given the significant opportunities related to the use of social media data for customers’ insight, we explore the factors driving information sharing behavior on SCSs. In this paper, we propose and empirically test a comprehensive theoretical model for customer information sharing behavior through analysis of online survey data as well as network and behavioral usage data of over four months from 1177 customers in a SCS. The research model was empirically validated with the use of both subjective and objective data in a longitudinal setting. Our results show that customer information sharing is influenced by both individual (i.e., reputation and the enjoyment of helping others) and social capital (i.e., out-degrees’ post, in-degrees’ feedback, customer expertise and reciprocity) factors. This study contributes to the existing literature by highlighting the role of directed social network in customer information sharing behavior on SCSs. We believe that the results of our study offer important insights to the IS research and practice.  相似文献   

THE DYNAMIC CHARACTERISTICS OF LONG SPAN ARCH STRUCTURE     

颜玉玲  张建周 《东南大学学报》1989,(1)

This paper presents a method for isolatedly solving the normal mode of vi-bration according to the uncoupling condition of vibrations inside and outside the archplane.The finite element method for curved beam elements is adopted to analyse the dy-namic characteristics of arch structures and the calculating program is made.The resultsobtained from Apple II microcomputer are compared with those from SAP5 program byan example,and are in good agreement.  相似文献   

大跨度钢管混凝土拱桥的稳定与振动     

彭卫  董熙强  杜时贵 《金华职业技术学院学报》2004,4(4):15-18,14

通过理论研究和数值计算，详细分析了大跨径钢管混凝土双肋拱桥的侧倾稳定性和地震响应。首先，根据双肋拱桥结构在竖向均布荷栽作用下的侧倾稳定临界力的近似解析解，讨论了横撑设置、横撑刚度等因素对稳定性的影响。其次，基于多点激振理论和拟静力位移概念，介绍了拱桥结构的动力特点和地震动作用下的响应，并讨论了行波效应的影响。分析表明，地震行波作用对大跨度拱桥影响很大，横撑设置对稳定性敏感。  相似文献   

Temporal processing and reading disability     

David L. Share  Anthony F. Jorm  Rod Maclean  Russell Matthews 《Reading and writing》2002,15(1-2):151-178

The present investigation examined thehypothesis that early auditory temporalprocessing deficits cause later specificreading disability by impairing phonologicalprocessing (Farmer & Klein 1995; Tallal1980, 1984). Temporal processing ability atschool entry was examined using Tallal'sRepetition Test in a large unselected sample ofover 500 children followed over subsequentyears. Although our data confirmed the presenceof certain non-speech auditory processingdeficits in children later classified asspecific reading-disabled, many findings wereclearly at odds with a causal interpretation ofthis relationship. (1) Reading-disabled (RD)children were impaired at school entry on thesubtest with long interstimulus intervals(ISIs) but not the critical short-ISIsubtest. (2) RD children were not inferior toreading-age (RA) controls. (3) A subgroup of RDchildren with evidence of temporal deficitswere no less proficient on later phonologicalor reading measures than RD children with noevidence of early temporal impairment. (4)Although there was a reliable concurrentcorrelation between temporal deficits andphonological awareness at school entry(suggesting a possible common causeexplanation), early temporal deficits did notpredict later phonological impairment,pseudoword processing difficulties, or specificreading disability. On the other hand, earlytemporal deficits did predict later oralreceptive vocabulary and reading comprehensionweaknesses. These findings suggest thatauditory temporal deficits in dyslexics may beassociated with the same dysphasic-typesymptoms observed by Tallal and her colleaguesin specific language-impaired populations, butdo not cause the core phonological deficitsthat characterize dyslexic groups.  相似文献   

The role of maternal mediation of writing to kindergartners in promoting literacy in school: A longitudinal perspective     

Aram  Dorit  Levin  Iris 《Reading and writing》2004,17(4):387-409

The current study follows up on Aram andLevin's (2001, Cognitive Development, 16, 831–852)analysis of the role of maternalwriting mediation among low SES Israelikindergartners. That study's main findingindicated that the quality of maternal writingmediation correlated concurrently withkindergartners' literacy skills aftercontrolling for socio-cultural measures. Thepresent study followed up the participants tothe second grade in school, and evaluated theirlevel of Spelling, Reading Comprehension, andLinguistic Knowledge two and a half years later. Theresults indicate that the children's literacymeasures in school were predicted by maternalwriting mediation in kindergarten beyond SESand the early literacy measures assessed in thekindergarten (Word Writing and LinguisticKnowledge). These results highlight thesignificance of early maternal writingmediation as a major factor in literacydevelopment.  相似文献   

金属拱型波纹屋盖加强后受力性能研究     

张德生 《嘉应学院学报》2006,24(3):109-112

建立了加强后的金属拱型波纹屋盖模型,利用ANSYS有限元分析软件对加强后的波纹拱进行了荷载作用下几何非线性有限元分析,并与原波纹拱进行了变形与应力的比较。计算结果表明,加强后的波纹拱对约束结构位移变形有较好的效果,且提高了结构的承载能力,这一结论为该结构进行抗风、抗雪等设计提供了有益参考。  相似文献