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71.
S.G. Tzafestas 《Journal of The Franklin Institute》1980,309(6):399-438
In this paper a variety of optimal control (OC) problems for distributed- parameter (DP) systems are approached using mathematical programming (MP). First, the principal DP models in current use are given, a variety of DP objective functions is provided, and the OC problems based on them are formulated. Second, these models and objective functions are converted in algebraic form, as required by MP, and the solution procedure of the OC problems via MP is outlined. Third, a representative set of nonlinear programming results applied to DP systems is presented, and finally, a numvber of application examples is given. 相似文献
72.
Research in the area of technology learning environments is tremendously complex. Tasks performed in these contexts are highly cognitive and mostly invisible to the observer. The nature of performance in these contexts is explained not only by the outcome but also by the process. However, evaluating the learning process with respect to tasks involving technology is difficult to measure objectively. As a result, audit trails (also called log or dribble files) are becoming extremely valuable tools in evaluating learning and performance in complex environments. This article reviews efforts of researchers in various areas, describes the nature of research using dribble files, and provides a framework on which investigators might build evaluations. 相似文献
73.
74.
Brian Byrne William L. Coventry Richard K. Olson Jacqueline Hulslander Sally Wadsworth John C. DeFries Robin Corley Erik G. Willcutt Stefan Samuelsson 《Journal of Research in Reading》2008,31(1):8-21
As part of a longitudinal twin study of literacy and language, we conducted a behaviour‐genetic analysis of orthographic learning, spelling and decoding in Grade 2 children (225 identical and 214 fraternal twin pairs) in the United States and Australia. Each variable showed significant genetic and unique environment influences. Multivariate analyses revealed very high genetic correlations among the variables, indicating that the same genes are involved in their aetiology. These genes are partly independent of those contributing to intelligence. A further analysis indicated that the covariation between decoding and orthographic learning is mediated by shared genes rather than by a direct causal path. The authors argue that a learning parameter, most directly assessed by orthographic learning in this study, underlies all three literacy variables. The results are also discussed in relation to Share's self‐teaching hypothesis, which may require modification. 相似文献
75.
Leon IG 《Child development》2002,73(2):652-663
The American definition of kinship based on biological ties, the practice of closed adoption, and stigmas associated with adoption may decisively influence adoption-related losses. Cross-cultural and historical accounts of adoption that do not apply to these contemporary American constructs of parenthood and practices of adoption suggest outcomes that are not as integrally based on loss. Adoption in infancy is defined as parenting a child with one set of (adoptive) parents and two (adoptive and birth) families. Implications for adoption research, policy, and practice are discussed. 相似文献
76.
This study evaluated a 2‐week residential program aimed at enhancing the science interest and persistence of high‐achieving 8th‐grade girls. Questionnaires were administered to 38 program participants (14 of whom were of minority ethnicity) and 173 applicants who did not attend the program, at 3 time points: preprogram, 1 year postprogram, and 4 years postprogram. Outcomes, measured postprogram, included science self‐concept and interest, persistence and aspirations in science, science activities, science course‐taking in high school, and plans for a science college major. There was no main effect of program participation on any of the outcome measures, but a significant Participation × Ethnicity interaction effect occurred for all but one of the outcome variables. At Time 2, and especially Time 3, nonminority participants tended to have the most positive outcomes, whereas minority participants tended to have the most negative outcomes, compared with applicants. Post hoc analyses showed that although nonminority girls overall were more advantaged, this difference did not explain results. Several interpretations for these findings are discussed, the most likely that some global feature of the program, not any intervention component, interacted over time with the girls' postprogram experience. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 393–414, 2003 相似文献
77.
The relationship between self reports of college experiences and achievement test scores 总被引:1,自引:3,他引:1
Gary R. Pike 《Research in higher education》1995,36(1):1-21
This study evaluated the feasibility of using students' self reports of the academic development and college experiences as proxies and policy indicators for a national assessment of undergraduate education. Results indicated that self reports of academic development should be used with care as proxies for a national test. Particularly important are issues of content overlap and differences in the measurement methods. Results from the second part of this study supported using self reports of college experiences as policy indicators to improve undergraduate education.Paper presented at the annual forum of the Association for Institutional Research, New Orleans, May 1995. 相似文献
78.
A Twin Study of Attachment in Preschool Children 总被引:3,自引:0,他引:3
The degree to which individual differences in child-parent attachment were mediated by genetic, shared environmental, and nonshared environmental influences was investigated. One hundred and ten preschool-aged twin pairs (N = 220) were assessed in the Strange Situation and coded using conventional four-way classifications and a continuous measure of attachment security. The degree of sibling similarity in attachment was substantial, with an overall concordance rate of 67% at the secure/insecure level. The degree of concordance was equally high in monozygotic and dizygotic twin pairs, 70% and 64%, respectively, suggesting little genetic influence but a moderate degree of discordance. Twin similarity on the continuous measure of attachment security was r(57) = .48 and r(53) = .38 for monozygotic and dizygotic twin pairs, respectively, also consistent with a modest role for genetic influence but a significant effect for shared and nonshared environment. The implications for genetic influences on the environment and for understanding nonshared and shared environmental influences are discussed. 相似文献
79.
The semantic differential technique was used in this study for the purpose of discovering similarities and differences in the meaning of words between teachers in training and counselors in training. A number of differences were revealed which indicate that teachers in training and counselors in training are not in accord as to the connotations of certain concepts. These differences suggest that counselors and counselor educators must strive for a greater understanding of the counselor's role in the school setting on the part of other education professionals. 相似文献
80.