多源遥感图像分级校正研究

遥感图像在进行几何精校正时．需采用地面控制点(GCPs)，这些控制点一般来源于地形图．因此．校正后遥感图像的坐标和精度主要决定于地形图．本文以遥感图像作为校正空间．对研究区内Quick Bird、SPOT-5、ETM 和TM多源遥感图像采用分辨率由高至低分级校正．对分辨率最高的Quick Bird图像校正所需的地面控制点坐标采用静态GPS地面实测的方法．使校正后的图像具有较高精度．研究结果表明：用高精度的图像作为校正空间具有较好的校正效果．研究所涉及的4个时相、5种分辨率和4个遥感平台的多源遥感图像，分级校正后的精度均较高。     

The effects of strategy training on high school students’ learning from science texts

This research examines the effects of a reciprocal teaching intervention aimed at providing high school students. with a repertoire of strategies to integrate text and visual aid information (graphs, diagrams) while learning in science. Experimental subjects received an hour of instruction each week for 7 weeks using SLIC (Summarise, Link, Image, Check) strategies to integrate the written word with the visual aid while Controls were taught under normal class teaching methods using the same materials. Post test ANOVA’s with Treatment (Experimental, Control) and Reading Ability (Average, Below average) as the factors showed superior recall of details by average ability students in the Experimental group but no significant differences in main idea recall nor on comprehension questions. All Experimental students included a graph in their recalls and they also significantly included more linking information in their texts on the graphs. The quality of their recall graphs was superior to those of the Control group. The results of a far transfer test showed no effects of training on transfer. Implications for future research and for teaching are discussed.     

A Comparison of Item Calibration Procedures in the Presence of Test Speededness

In the presence of test speededness, the parameter estimates of item response theory models can be poorly estimated due to conditional dependencies among items, particularly for end‐of‐test items (i.e., speeded items). This article conducted a systematic comparison of five‐item calibration procedures—a two‐parameter logistic (2PL) model, a one‐dimensional mixture model, a two‐step strategy (a combination of the one‐dimensional mixture and the 2PL), a two‐dimensional mixture model, and a hybrid model‐–by examining how sample size, percentage of speeded examinees, percentage of missing responses, and way of scoring missing responses (incorrect vs. omitted) affect the item parameter estimation in speeded tests. For nonspeeded items, all five procedures showed similar results in recovering item parameters. For speeded items, the one‐dimensional mixture model, the two‐step strategy, and the two‐dimensional mixture model provided largely similar results and performed better than the 2PL model and the hybrid model in calibrating slope parameters. However, those three procedures performed similarly to the hybrid model in estimating intercept parameters. As expected, the 2PL model did not appear to be as accurate as the other models in recovering item parameters, especially when there were large numbers of examinees showing speededness and a high percentage of missing responses with incorrect scoring. Real data analysis further described the similarities and differences between the five procedures.     

Effects of Restructuring Training and Cognitive Style

Herman Witkin's research in differentiation theory proposed a conceptual framework describing the cognitive style known as field dependence‐independence. The operational measures of this construct are restructuring skills and interpersonal competencies, and were originally conceived to be fixed in an individual. A recent reconceptual‐isation, however, suggested that there may be some malleability in learning strategies that flow from cognitive style. Learners predisposed to field dependence might gain access to restructuring skills brought to problem‐solving situations by field independents. This study undertook to examine the effects and practicability of restructuring training as a means of addressing individual learner differences. Field independent subjects significantly out‐scored field‐dependent subjects on all three test tasks in the control group. Experimental group field independents did not significantly outscore experimental field dependents. Training enhanced field dependent subject performance on two dependent measures tasks. There was interaction across treatment and field dependence on all three dependent measures.     

Teaching text comprehension strategies to adult poor readers

This study demonstrated the benefit of teaching text comprehension strategies to adults who are poor readers. Subjects (n=90) were students enrolled in adult education programs who earned a score of 90 or above on theSlosson Intelligence Test and a score equivalent to a 3rd–7th grade reading level on theNelson Denny Reading Test. These subjects were randomly assigned to one of three experimental or two control conditions. Experimental conditions were: self questioning and summarizing instruction (total condition); self questioning instruction only; or summarizing instruction only. Control conditions were: tests and experimental materials without instruction; or tests only. Experimental subjects were instructed in small groups for six 45 minute sessions using an instructional method which features informed self control training and guided learning. Analyses of covariance showed significant differences between the performances of the groups. On one measure, a question task, subjects who self questioned and summarized, and subjects who self questioned, significantly out performed the two controls. On a second measure, a free recall task, subjects who self questioned and summarized significantly outperformed control groups combined. Contrary to expectations, the self questioning and summarizing condition (total condition) did not significantly outperform the other experimental groups.     

Systems Modelling and the Development of Coherent Understanding of Cell Biology

This article reports on educational design research concerning a learning and teaching strategy for cell biology in upper‐secondary education introducing systems modelling as a key competence. The strategy consists of four modelling phases in which students subsequently develop models of free‐living cells, a general two‐dimensional model of cells, a three‐dimensional model of plant cells, and finally they are engaged in formal thinking by modelling life phenomena to a hierarchical systems model. The strategy was thought out, elaborated, and tested in classrooms in several research cycles. Throughout the field‐tests, research data were collected by means of classroom observations, interviews, audio‐taped discussions, completed worksheets, written tests, and questionnaires. Reflection on the research findings eventuated in reshaping and formalizing the learning and teaching strategy, which is presented here. The results show that although acquiring systems thinking competence at the metacognitive level needs more effort, our strategy contributed to improving learning outcomes; that is, acquisition of a coherent conceptual understanding of cell biology and acquisition of initial systems thinking competence, with modelling being the key activity.     

Reading Angles in Maps

Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty‐eight children (age 47:15–53:30 months) were presented with fragments of geometric maps, in which angle sections appeared without any relevant length or distance information. Children were able to read these map fragments and compare two‐dimensional to three‐dimensional angles. However, this ability appeared both variable and fragile among the youngest children of the sample. These findings suggest that 4‐year‐old children begin to form an abstract concept of angle that applies both to two‐dimsional and three‐dimensional displays and that serves to interpret novel spatial symbols.     

Training Students to Use Maps to Increase Text Recall

In this study, high school students were trained to use adjunct maps strategically while studying a History text. Subjects were randomly assigned to either a control or map training group which read a lengthy passage which was accompanied by three maps. The control group was instructed to study the materials and write an essay about them. The map training group was instructed to study the materials and to place important event information from the text on their maps; they also discussed how their maps could be used to help them remember the text. One week later multiple choice, probed recall, free recall, and map recall tests were administered. Three weeks after training both groups read a transfer text and were instructed to use the attached map to help them remember the information. Free recalls were gathered after a short delay. Results showed that map training subjects obtained higher scores on all of the training text recall measures and on the main idea level transfer text measures. High ability map training subjects also recalled more details. Maps used in the transfer task showed trained subjects using the strategies they had been taught.     

Students' rating of Speak Out television programme

This study is an evaluation of Speak Out television programme in Lagos State. A total of 300 junior secondary school students of Lagos State participated in the study: 150 class I and 150 class II students randomly selected from the six secondary schools in the two environment settings (200 urban and 100 rural).
Two groups of subjects featured—Experimental: representing students taught using the instructional television programme approach, and Control: representing those taught the same subject matter of the instructional television programme using the group activity (socio-drama) without the stimulus of the television programme.
The research tested three hypotheses. The findings revealed that there were significant differences found in the performance of the Experimental groups that were taught with the instructional television programme approach. In addition, there was a significant difference found between location and instructional method. The classes' performances were not significant. The article discusses the findings and makes some recommendations     

Speed isn’t everything: a study of examination marking

The question of whether marking speed is related to marking accuracy is important for training examiners and planning realistic marking schedules. We explored marking speed in the context of a past examination for an international biology qualification for 14‐ to 16‐year‐olds. Forty‐two markers with differing backgrounds experimentally marked 23 diverse examination questions. All responded to questionnaires about times taken to mark two of four samples of candidate responses. We demonstrated a positive practice effect for inexperienced markers, who became significantly faster during the course of their marking whilst maintaining their accuracies; there was no clear trade‐off between speed and accuracy. The benefits of marking practice and background experience are distinct phenomena. To improve accuracy, longer term investments in education and experience are needed.     

Numerical investigation of cavitating flow behind the cone of a poppet valve in water hydraulic system

Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNGk-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera. The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good agreement with the numerical result. Project supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China (No. 50175097)     

基于半监督与词向量加权的文本分类研究

针对文本分类领域的有监督学习往往需要大量精准标注样本但大量人工标注困难的问题,提出一种新型的半监督学习方式,通过协同训练合理使用大量未标记训练样本,通过添加不同分类的文本特征噪声解决传统协同半监督学习方法中模型参数趋于统一的问题,同时提高分类模型的分类能力。针对传统深度学习方法中文本特征权重一致导致的分类特异性特征不突出问题,在训练模型中加入 self-attention 机制对文本句子特征权重进行提取,并通过句子加权方式突出特异性分类特征。实验结果表明,通过半监督学习方式同时使用少量已标注数据进行训练,模型能够达到 91.4%的准确率,召回率达到 84.3%,与有监督训练方式的分类准确能力相近,从而解决大量人工标注问题,具有一定的使用价值。     

The Reification of Goal Structures in a Calculus Tutor: Effects on Problem‐Solving Performance

In an initial experiment with a minimal version of a calculus tutor, it was determined through analyses of verbal protocol data that students were attempting to execute a fairly standard working‐backwards, means‐ends strategy to solve systems of equations, but were having difficulty maintaining the requisite goal stack. To remedy this problem, an enhancement to the interface of the tutor was designed which allowed students to post and display the subgoals required by the means‐ends strategy. As students progressed through problems, individual subgoals were boxed and shaded to indicate which subgoals were active and which had been satisfied, respectively.

An experiment testing the effects of this type of goal posting showed that student problem‐solving performance improved in terms of both speed and accuracy while the goal blackboard was present. Furthermore, many of the positive effects persisted after the goal blackboard was taken away.

Two explanations for the beneficial effects of goal posting are offered. The first is that the display served as external memory which maintained goal structures that would have otherwise been lost in the shuffle of problem solving. The second, perhaps more compelling explanation is that, in the process of posting goals, subjects learned something about the underlying structure of problems.     

BP神经网络在多维非线性函数拟合中的应用

为了解决常规方法拟合多维非线性函数的预测结果精度较低问题,采用非线性映射能力较强的BP神经网络进行多维非线性函数拟合。通过对BP神经网络结构及训练过程的分析,依据给定的两维非线性函数构建BP神经网络模型,并利用MATLAB软件对BP神经网络进行预测。仿真结果表明,BP神经网络对于两维非线性函数有良好的拟合能力,拟合误差小、收敛速度快,也使该方法具有较好的推广性。     

ACCURACY AND SPEED OF MEMORY IN DEPRESSED AND ORGANIC AGED

Forty‐three subjects aged 50 and over were tested on a Sternberg recognition‐memory task to explore the relative effects of depression and altered brain function on short‐term memory in later life. Organic, depressed, and control subgroups were compared on accuracy and speed of response. Speed‐of‐memory scanning was differentiated from other speed‐of‐response components; separate estimates of memory efficiency and subjective response criteria were calculated from accuracy data by signal‐detection methods. Organic subjects performed much less accurately and quickly than others, showing great variability of response speeds. Depressed subjects performed less accurately and quickly than controls, particularly on negative trials, but did not differ in rate of memory scanning. Depression was associated with poorer memory efficiency and laxer response criteria (greater tolerance for false‐positive errors). Slower and less accurate responding was also associated with a poorer educational background. Many performance differences were best accounted for by the additive effects of depression and educational background, rather than by either variable individually. The association of laxer criteria with depression alone, however, was discussed in terms of a possible acquiescent response bias in depression.     

Training of component reading skills

Fifteen reading-disabled boys, classified according to reading subskill deficits, formed three subgroups: Oral Reading, Associative, and Sequential. On the rationale that training procedures emphasizing accuracy and speed of response to letters, syllables, and words would improve reading skills, the children were trained daily for two and one-half months. Two schedules of testing and training allowed for an untrained control group and a follow-up group. The results indicated that the computer-assisted training procedures were not only effective in improving component reading skills, but in addition there was a transfer of training to achievement measures of reading word recognition. This study lends support to the hypothesis that training according to subgroup classification, using training procedures which incorporate an application of the automaticity theory and a combination of task-analytic and process-oriented models, is an effective training approach for reading-disabled children. This research was funded by a grant from the Toronto Hospital for Sick Children Foundation, Toronto, Canada, and a scholarship from the Natural Science and Engineering Research Council, Ottawa, Canada.     

Using a games console in the primary classroom: Effects of ‘Brain Training’ programme on computation and self‐esteem

It is known that computer games are motivating for children, but there is limited direct evidence of their effects on classroom learning. The aim of this exploratory study was to investigate the effects of a commercial off‐the‐shelf computer game on children's mental computation skills and on aspects of self‐perceptions. A pre–post design was employed. The participants were 71 primary school children (10–11 years old) from three classes. In School 1, a class of 21 children used a games console for 20 minutes each day, running a ‘brain training’ game. Two comparison groups were used. In School 2, 31 children used ‘Brain Gym’ techniques in their class over the treatment period. In school three, a class of 19 children acted as no‐treatment controls. The treatment period was 10 weeks. Significant pre–post gains were found in the games console group for both accuracy and speed of calculations, while results for the two comparison groups were mixed. The games console group showed significant gains in global self‐esteem, but not in other aspects of self‐concept. The comparison groups showed no significant gains in any area of self‐perceptions. There is a need now for upscaling to investigate generalisability.     

Encoding tactics in the retention of maps

Two experiments were designed to determine which of two encoding tactics learners use to remember maps and whether one or the other differentially preserves locational memory for mapped features. Experiment 1 subjects were presented a map with either low or high spatial distinction, with half of the subjects receiving general instruction to cluster the map's features. Results showed that the subjects have an apparent propensity to encode mapped features using a semantically based encoding tactic; yet the visuospatial properties of a map influence the employment of this tactic. In Experiment 2, the encoding instructions were made more specific by informing subjects to encode mapped features either conceptually or spatially or simply to study the map. Half the subjects in each group recalled mapped features either by listing them or by reconstructing the entire map. Results showed that a well-defined set to employ specific mechanisms of encoding differentially affects retention, but memory for location is preserved by an encoding tactic that is spatially based. Findings are discussed in terms of their theoretical and instructional implications.     

Effects of a Pre‐service Teacher Preparation Programme on Effective Instruction

A quasi‐experimental, treatment‐control group investigation was designed to test the effects of a pre‐service training course on effective instruction. Research findings from teacher effects research and cognitive strategy instruction were translated into two direct instructional models: one model for explicit or well‐structured skills and one model for implicit skills or higher‐level thinking strategies. Following a course on effective instruction from their teacher educators, student teachers implemented standardised lessons to apply selected research‐derived teaching behaviours and to increase pupil engagement rates. Based on trained observers’ pre‐and post‐training classroom observations, a significant treatment effect was found for student teachers’ teaching behaviours regarding effective instruction and for pupil engagement rates. Ratings from supervising teachers also showed that the student teachers who participated in the course on effective instruction used the recommended instructional skills after completion of the course significantly better than prior to the course.     

Phrase Reading Training and Reading Achievement

This study examined the independent and interactive effects of supplement format (knowledge map vs. text vs. no supplement) and strategy (cooperative learning vs. cooperative teaching vs. individual study) on learning. After training and practice sessions, subjects studied a science and math passage over which they were tested. Two individual difference measures were also taken and combined into a general ability score. Repeated-measures analysis of variance of the recall variables indicated that (a) high ability subjects outperformed low ability subjects, and (b) cooperative learning with map supplements had a mutually facilitative effect on the low ability subjects’ recall.