Effect of boundary conditions and convection on thermally induced motion of beams subjected to internal heating     

MALIK Pravin KADOLI Ravikiran GANESAN N. 《浙江大学学报(A卷英文版)》2007,8(7):1044-1052

Numerical exercises are presented on the thermally induced motion of internally heated beams under various heat transfer and structural boundary conditions. The dynamic displacement and dynamic thermal moment of the beam are analyzed taking into consideration that the temperature gradient is independent as well as dependent on the beam displacement. The effect of length to thickness ratio of the beam on the thermally induced vibration is also investigated. The type of boundary conditions has its influence on the magnitude of dynamic displacement and dynamic thermal moment. A sustained thermally induced motion is observed with progress of time when the temperature gradient being evaluated is dependent on the forced convection generated due to beam motion. A finite element method (FEM) is used to solve the structural equation of motion as well as the heat transfer equation.  相似文献   

Parents as adult learners in family-centered early education     

Bodner-Johnson B 《American annals of the deaf》2001,146(3):263-269

Several concepts from the adult learning literature are described that relate to working with parents of young children who are deaf. It is proposed that an adult learner perspective makes an important contribution to the family-centered philosophy and knowledge base that guide the development of practice in early intervention. Three areas are discussed: the context for adult learning, that is, the life situation of adults, including their social roles and responsibilities and experience; learning related to transitions in the adult life cycle; and transformative learning, which examines the ways people make changes in how they understand their experience. Implications for practice in early childhood education are presented.  相似文献   

自密实混凝土和高性能混凝土在预制法施工中性能的比较研究     

ROUGEAU  MAILLARD  C.MARY-DIPPE  张金强 《石家庄铁路工程职业技术学院学报》2002,1(2):36-39

在混凝土预制厂中制作挡土墙时，对自密实混凝土(简称SCC)和高性能混凝土(简称HPC)进行了比较，试验表明，SCC某种情况下可以替代HPC。在试验室中进行的性能研究，包括材料的微观结构分析及与之相关的耐久性，尤其突出了一系列系数的测定(渗透性、氯化物的扩散性、碳化程度等)以及分别在有和没有防冻盐两种条件下的抗冻性。试验室条件下的试验结果，显示了SCC抵抗CO2和氯化物转移的良好性能。在研究中，SCC(尤其是BAP3)也显示了比HPC更加良好的抗冻性。  相似文献   

Risk factors for the perpetration of child sexual abuse: a review and meta-analysis   总被引：1，自引：0，他引：1  

Whitaker DJ  Le B  Karl Hanson R  Baker CK  McMahon PM  Ryan G  Klein A  Rice DD 《Child abuse & neglect》2008,32(5):529-548

OBJECTIVES: Since the late 1980s, there has been a strong theoretical focus on psychological and social influences of perpetration of child sexual abuse. This paper presents the results of a review and meta-analysis of studies examining risk factors for perpetration of child sexual abuse published since 1990. METHOD: Eighty-nine studies published between 1990 and April of 2003 were reviewed. Risk factors were classified into one of the following six broad categories: family factors, externalizing behaviors, internalizing behaviors, social deficits, sexual problems, and attitudes/beliefs. Sex offenders against children (SOC) were compared to three comparison groups identified within the 89 studies: sex offenders who perpetrated against adults (SOA), non-sex offenders, and non-offenders with no history of criminal or sexual behavior problems. RESULTS: Results for the six major categories showed that SOC were not different from SOA (all d between -.02 and .14) other than showing lower externalizing behaviors (d=-.25). Sex offenders against children were somewhat different from non-sex offenders, especially with regard to sexual problems and attitudes (d=.83 and .51). Sex offenders against children showed substantial differences from non-offenders with medium sized effects in all six major categories (d's range from .39 to .58). CONCLUSION: Child sex offenders are different from non-sex offenders and non-offenders but not from sex offenders against adults. PRACTICE IMPLICATIONS: This study suggests that the presence of general risk factors may lead to a variety of negative behavioral outcomes, including the perpetration of child sexual offending. Family factors were strongly related to the perpetration of child sex offending (vs. non-sexual offending or non-offending) and may be valuable intervention points for interrupting the development of child sex offending, as well as other negative behaviors. Other potential points for intervention may focus on the development of appropriate social and emotional skills that contribute to sexual offending.  相似文献   

Attempted and completed incidents of stranger-perpetrated child sexual abuse and abduction     

Gallagher B  Bradford M  Pease K 《Child abuse & neglect》2008,32(5):517-528

OBJECTIVE: To establish the prevalence, typology and nature of attempted or completed incidents of stranger-perpetrated sexual abuse or abduction of children "away from home". METHODS: A questionnaire was completed by 2,420 children (83% response rate) aged 9-16 years in 26 elementary and high schools in North-West England. RESULTS: Of these children, 19.0% (n=461) reported that they had been the victims of any attempted or completed sexual abuse or abduction incident away from home at some point in their lives. Of these children, 161 (6.7% of the original sample) reported that the "last" incident had been perpetrated by a stranger. Based upon these last incidents, four main types of attempted or completed CSA or abduction incident were identified: indecent exposure (40.8% of victims), touching (25.8%), and abduction (23.1%), each occurring on their own; and incidents involving multiple types of act (10.2%). The majority of these abductions (91.1%) and touching incidents (50.9%) were attempted as opposed to completed. Rates of victimization were generally higher among girls than boys (10.4% vs. 4.2%, p<.001). A sizeable minority of victims had experienced sexual abuse or abduction previously (28.8%). The large majority of incidents were carried out by males (88.2%). Most incidents occurred when children were accompanied by their peers (67.9%). Many victims were frightened by their experience (46.9% very frightened) and the large majority made a disclosure (79.9%). Only a minority of incidents were reported to the police (33.3%). CONCLUSIONS: Incidents of attempted and completed stranger CSA and abduction are distinct from CSA and abduction by known persons, go against stereotypes, are complex, and give rise to a number of key issues that may have implications for prevention and intervention. PRACTICE IMPLICATIONS: Professionals involved in child protection should undertake work to reduce the risk of existing victims of CSA or abduction becoming victims of stranger CSA or abduction, and the risk of attempted incidents becoming completed ones. They also need to encourage the disclosure and reporting of attempted and completed stranger CSA and abduction incidents.  相似文献   

Stress analysis of anisotropic thick laminates in cylindrical bending using a semi-analytical approach   总被引：1，自引：0，他引：1  

LU Chao-feng LIM C.W. XU Feng 《浙江大学学报(A卷英文版)》2007,8(11):1740-1745

Semi-analytical elasticity solutions for bending of angle-ply laminates in cylindrical bending are presented using the state-space-based differential quadrature method (SSDQM). Partial differential state equation is derived from the basic equations of elasticity based on the state space concept. Then, the differential quadrature (DQ) technique is introduced to discretize the longitu- dinal domain of the plate so that a series of ordinary differential state equations are obtained at the discrete points. Meanwhile, the edge constrained conditions are handled directly using the stress and displacement components without the Saint-Venant principle. The thickness domain is solved analytically based on the state space formalism along with the continuity conditions at interfaces. The present method is validated by comparing the results to the exact solutions of Pagano’s problem. Numerical results for fully clamped thick laminates are presented, and the influences of ply angle on stress distributions are discussed.  相似文献   

关键词:生活     

《语文教学通讯·B刊》编辑部 《中国小学语文教学论坛》2016,(7)

单凭一支笔、一张纸,必然写不成什么好文字.进一步说,单凭能言善辩,也写不成什么好文字.能言善辩只是一种技术,必须有东西可说,才可以运用这种技术.要有东西可说,就不是作文当时的工夫了,须在生活中间随时观察,随时体会.观察得精,体会得深,那才有了可说的东西,说出来也自然有了技术.技术是从生活经验得来的,不是某几个文学家创造出来的,每一个文学家的技术都是从他的生活经验得来的,这是执笔作文的人首先要记住的事.  相似文献   

An Exploratory Analysis of a Subjective Well-Being Model for Chinese University Students     

Xiaoxi DONG  Lilia C. DIBELLO  Mehmet TÜREGÜN  Ruth A. BAN 《Frontiers of Education in China》2020,15(3):403

College students experience great stress due to many factors, such as an uncertain future, academic responsibilities, and pressures imposed by social communication. Many institutions of higher education are focusing on how to mediate stressful situations and increase the subjective well-being (SWB) of students to sustain a lifestyle focused on wellness. The online survey used for this study focused on testing an exploratory SWB model by implementing partial least squares structural equation modeling (PLS-SEM) techniques. The participants were 470 college-aged students enrolled in seven different institutions in six cities across China. Findings yielded a good model fit (the Standardized Root Mean Squared Residual [SRMR] = .054) with the validity of manifest variables, reliability of the latent variables (LVs), and overall SWB model indicating moderate predictiveness (GoF R2 = .476) by the LVs. Additionally, all of the direct path coefficients and indirect path coefficients that consisted of four partial mediators and one full mediator yielded statistically significant results via bootstrapping. Furthermore, path coefficients for utilization of emotion to life satisfaction for the cognitive exercise group were significantly higher than for the non-cognitive exercise group. The findings illustrated a good model fit for an exploratory SWB model that can predict an individual’s SWB, and cognitive and non-cognitive exercises had different effects on the individuals’ SWB.  相似文献   

旅行中的完美时刻     

T.C. Lower 《海外英语》2006,(4):23

When was the last time you experienced a perfect moment? You know,the kind of moment when everything is in sync and where a certain clarity surrounds the scene, setting it apart from the rest of the world.  相似文献   

教授和企业家:一个技术转让的事例研究     

G.R.苏里万  G.G.杜布里克  唐正秋 《中山大学学报论丛》1992,(4)

1 丹特克(Dantec)事例研究在1982年,我那时是化学工程教授,正集中精力在教三年级的化学变化过程控制。突然,一声轻轻的敲门声惊动了教室的人。那就是杰拉德·杜布里克,丹特克电子公司董事长。他听说我知道一点化学过程控制,便想找我谈一谈粮食干控技术。  相似文献