Wavelet-based deconvolution of ultrasonic signals in nondestructive evaluation   总被引：1，自引：0，他引：1  

OROZCO Rubén 《浙江大学学报(A卷英文版)》2006,7(10):1748-1756

INTRODUCTION Deconvolution of ultrasonic signals is defined as the solution of the inverse problem of convolving an input signal, known as the system function h(n), with a medium reflectivity function x(n) and can be rep- resented by y(n)=h(n)*x(n) η(n), (1) where y(n) is the measured signal, * denotes the convolution operation and η(n) is the additive noise. Recovering x(n) from the observation y(n) leads to improving the appearance and the axial resolution of the RF-signals by removin…  相似文献   

Examining student teachers’ engagement with the theory-practice link in initial teacher education     

Sylvia Y. F. Tang  Angel K. Y. Wong  Dora D.Y. Li  May M. H. Cheng 《师资教育杂志》2019,45(2):123-139

The theory-practice debate has been a perennial issue in initial teacher education (ITE). By reporting a mixed-methods study in an ITE programme characterized by a university-based ‘theory-first’ approach in Hong Kong, this study offers useful empirical evidence to analyse the theory-practice issue. 346 student teachers of a BEd Programme participated in the quantitative survey, 15 of whom were interviewed. The quantitative findings showed significant positive correlations between three types of perceived professional competence and two aspects of student teachers’ engagement with the theory-practice link. The qualitative findings offered an in-depth understanding of the ways in which student teachers connected theoretical knowledge learned in ITE coursework and practical experience in ITE fieldwork in developing their professional competence: (1) theoretical knowledge as a guide for professional decisions and a tool for reflection on practice; (2) practicalizing theoretical knowledge: adapting theoretical knowledge to practice situations. In the process of engagement, theoretical knowledge was transformed and adapted to practice situations when student teachers coped with the challenges of the teaching contexts in their ITE fieldwork. While affirming the value of student teachers’ engagement with the theory-practice link, the findings of the study shed light on ITE practices for preparing student teachers for such engagement.  相似文献   

Gender differences in the risk for delinquency among youth exposed to family violence     

Herrera VM  McCloskey LA 《Child abuse & neglect》2001,25(8):1037-1051

OBJECTIVE: The purpose of this research was to illuminate gender differences in adolescent delinquency against a backdrop of childhood exposure to both marital violence and physical child abuse. Specifically, analyses were performed to trace the unique effects of exposure to either form of family violence (marital or child) on the violent and nonviolent delinquency of boys and girls. METHOD: This is a prospective study of 299 children who were interviewed with their mothers in 1991 about forms of abuse in the family. Approximately 5 years later a search of juvenile court records was performed for these same children. Details on the nature of the crimes were collected. Outcome variables included: (1) whether there was ever an arrest; and (2) whether there was ever an arrest for a violent crime. RESULTS: Preliminary analyses indicated no gender differences in overall referral rates to juvenile court, although boys were more likely than girls to be referred for property, felony, and violent offenses. Exposure to marital violence in childhood predicted referral to juvenile court. Girls with a history of physical child abuse were arrested for violent offenses more than boys with similar histories, but the context of violent offenses differed dramatically by gender: Nearly all referrals for a violent offense for girls were for domestic violence. CONCLUSIONS: Although boys and girls share similar family risk factors for delinquency, girls are more likely than boys to be arrested for violent offenses in the aftermath of child physical abuse. These findings suggest that it takes more severe abuse to prompt violence in girls than is necessary to explain boys' violent offending.  相似文献   

Long-Term Effects of Food Supplementation and Psychosocial Intervention on the Physical Growth of Colombian Infants at Risk of Malnutrition     

Charles M. Super  M. Guillermo Herrera  José O. Mora 《Child development》1990,61(1):29-49

280 Colombian infants at risk of malnutrition were randomly assigned to 1 of 4 experimental groups formed by the presence/absence of 2 interventions: (1) food supplementation for the entire family, from mid-pregnancy until the target child was 3 years old, and (2) a twice-weekly home-visiting program to promote cognitive development, from birth until age 3. All families received free medical care and were studied prospectively. At 3 years of age, children who had received food supplementation averaged 2.6 cm and 642 grams larger than controls. Home visiting and supplementation together reduced the number of children with severe growth retardation. 3 years after intervention (age 6), supplementation effects remained. Children in the home visit condition had become larger than controls, by 1.7 cm and 448 grams. The interactive effect to reduce stunting was marginally significant at this age, and the overall distribution of scores was improved. Other results suggest that changes in family functioning as well as biological mechanisms account for the observed pattern of results.  相似文献   

Study persistence and academic achievement as a function of the type of competing tendencies     

Willy Lens  Marlies Lacante  Maarten Vansteenkiste  Dora Herrera 《European Journal of Psychology of Education - EJPE》2005,20(3):275-287

In order to understand and predict students’ achievement and persistence at learning activities, many contemporary motivational models consider how much students are motivated for their school work. However, students’ achievement and persistence might not only be affected by their amount of study motivation, but also by the motivation to engage in competing alternative activities, as suggested three decades ago by Atkinson and Birch in their “Dynamics of Action” (1970). Building on this line of theorizing, the present contribution indicates that it is not only instructive to consider the level of students’ motivation for these competing activities, but also the type of activities they engage in, that is leisure vs. working activities. Two studies demonstrated that whereas time spent on working activities is inversely related to study motivation, attitude, persistence and academic achievement, such relationships were not found for leisure time engagement. Spending some time on leisure time activities does not interfere with optimal learning.  相似文献   

Communities of Caring: Developing Curriculum That Engages Latino/a Students’ Diverse Literacy Practices     

Rosario Ordoñez-Jasis  KaiLonnie Dunsmore  George Herrera  Carlos Ochoa  Laura Diaz 《Journal of Latinos & Education》2016,15(4):333-343

This study investigates the learning and work of a community of practice that engaged in a specific inquiry around family/community literacy and the development of a culture of caring that would connect family/community/school literacies in ways that allowed their mostly Latino/a students to develop positive student identities, enhanced personal connections to their peers, and stronger experiential responses to literacy instruction.  相似文献   

Conflict, Understanding, and Relationships: Developments and Differences in the Preschool Years     

Judy Dunn  Cheryl Slomkowski  Nancy Donelan  Carla Herrera 《Early education and development》1995,6(4):303-316

Children's conflict management in three close relationships was studied longitudinally in 38 second born children, observed at home with their mothers and siblings at 33 months and at 47 months, and with friends at 47 months. Children used significantly more other-oriented argument with friends than with their mothers or siblings. Their use of reasoned argument with their siblings, but not their mothers, was related to their emotional understanding assessed formally at 40 months. The emotional context of conflict interactions was found to be important as an influence on children's use of reasoned argument, with less reasoning shown by children when they were upset at 33 months. The differences in patterns over time and in links with emotional understanding for these different relationships is discussed, and the significance of child-child interaction in the development of social understanding is highlighted.  相似文献   

The contribution of non-formal learning in higher education to student teachers’ professional competence     

Sylvia Y. F. Tang  Angel K. Y. Wong  Dora D. Y. Li  May M. H. Cheng 《师资教育杂志》2017,43(5):550-565

This article reports a mixed methods study on the contribution of various aspects of pre-service student teachers’ learning in initial teacher education (ITE) to their professional competence in a Five-year Bachelor of Education Programme in Hong Kong. Special attention is given to how student teachers’ non-formal learning in higher education contributes to their professional competence, an under-researched area in teacher education. A total of 282 student teachers participated in the quantitative survey, 18 of whom were interviewed. Although  Undergraduate Learning Experience: Formal Learning and Non-formal Learning was not the most highly rated factor, multiple regression indicated that it was the only ITE professional learning factor that significantly predicted all dimensions of professional competence. This supports the hypothesis that non-formal learning as a part of learning in higher education makes a significant contribution to student teachers’ professional competence. The qualitative findings showed that non-formal learning provided opportunities for service learning, co-curricular activities, and student exchange programmes with different objects of engagement. Student teachers constructed pedagogical content knowledge, general pedagogical knowledge, and knowledge of context through hands-on experiences, professional dialogue with practitioners, and observations of others’ practice. Such knowledge contributed to their competence in classroom teaching and to work in schools. Implications for ITE are discussed.  相似文献   

Developing professional skills in journalism through blogs     

Paula Hodgson  Dora Wong 《Assessment & Evaluation in Higher Education》2011,36(2):197-211

The curriculum for journalism is being forced to change because the traditional print‐based and broadcast modes are being challenged by wide and easy access to online mass communication. Primarily, students need to develop proficiency in writing, editing and publishing. However, they are also expected to be skilled in the Web medium as they venture into their careers, and weblogs offer a dynamic platform to develop these skills. Based on a statistical summary of student comments on the performance criteria for a blog project, a focus group interview and survey results, this paper will discuss the findings from the introduction of a course‐based blog to an undergraduate course in Hong Kong, including: (1) the technical challenge of making Web features; (2) the perception of proficiency in online publishing; (3) the evaluative skills developed through a peer‐review process; and (4) the development of a learning community through writing in blogs.  相似文献   

Ara Irititja and Ara Winki in the APY Lands: connecting archives to communities through mobile apps on portable devices     

Dora Dallwitz  John Dallwitz 《档案与原稿》2019,47(1):35-52

ABSTRACT

Ara Irititja is an enduring and multifaceted project that returns and collectively documents Anangu historical material and preserves it for the future. This paper explains why the archival project has been so effective in engaging Indigenous communities and what it is doing to ensure its longevity. In particular, the paper provides details about a new pilot project which has resulted in a software application entitled Ara Winki No. 1, ‘a whole lot of stories’, specifically for use on portable electronic devices, which delivers historical and cultural content of relevance to Anangu in local languages and works to connect the existing archive to younger generations.  相似文献