CMMB系统的整数倍载波频偏估计方法

在中国移动多媒体广播(CMMB)系统中,发送端的加扰使基于导频相关的整数倍载波频偏估计方法无法正常工作。针对该问题,提出一种适用于CMMB系统的整数倍载波频偏估计方法。利用CMMB帧结构中特有的同步信号进行整数倍载波频偏估计,避免发送端加扰对频偏估计的影响。仿真结果表明,该方法在低信噪比、高多普勒频偏的多径信道下仍具有良好的估计性能。     

Self-assessment and task selection in learner-controlled instruction: Differences between effective and ineffective learners

Learner-controlled instruction is often found to be less effective for learning than fixed or adaptive system-controlled instruction. One possible reason for that finding is that students – especially novices – might not able to accurately assess their own performance and select tasks that fit their learning needs. Therefore, this explorative study investigated the differences in self-assessment and task-selection processes between effective and ineffective learners (i.e., in terms of learning gains) studying in a learner-controlled instructional environment. Results indicated that although effective learners could more accurately assess their own performance than ineffective learners, they used the same task aspects to select learning tasks. For effective learners, who were also more accurate self-assessors, the self-assessment criteria predicted subsequent task selection. The results are discussed, particularly with regard to their potential to provide guidelines for the design of a self-assessment and task-selection training.     

Learning science in a virtual reality application: The impacts of animated-virtual actors’ visual complexity

As the technology in computer graphics advances, Animated-Virtual Actors (AVAs) in Virtual Reality (VR) applications become increasingly rich and complex. Cognitive Theory of Multimedia Learning (CTML) suggests that complex visual materials could hinder novice learners from attending to the lesson properly. On the other hand, previous studies have shown that visual complexity correlates with presence and may increase the perceived affective quality of the virtual world, towards an optimal experience or flow. Increasing these in VR applications may promote enjoyment and higher cognitive engagement for better learning outcomes. While visually complex materials could be motivating and pleasing to attend to, would they affect learning adversely? We developed a series of VR presentations to teach second-year psychology students about the navigational behaviour of Cataglyphis ants with flat, cartoon, or lifelike AVAs. To assess learning outcomes, we used Program Ratings, which measured perception of learning and perceived difficulty, and retention and transfer tests. The results from 200 students did not reveal any significant differences in presence, perceived affective quality, or learning outcomes as a function of the AVA’s visual complexity. While the results showed positive correlations between presence, perceived affective quality and perception of learning, none of these correlates with perceived difficulty, retention, or transfer scores. Nevertheless, our simulation produced significant improvements on retention and transfer scores in all conditions. We discuss possible explanations and future research directions.     

The influence of collaboration styles to children’s cognitive performance in digital problem-solving game “William Adventure”: A comparative case study

Since a large variety of digital games have been used in many fields for educational purposes, their real functions in learning have caught much attention as well. This study first defines learning characteristics of problem-solving digital games and their corresponding cognitive levels, then designs and develops a problem-solving game in accordance to the criteria. Tasks in the game context are inter-related to each other so that players need to critically and creatively think about problem solutions. Learners’ task analyses are performed to observe four elementary learners’ gaming paths, behaviors and cognitive activities, individually and collaboratively. System documentation, video recording, researcher observation, and interviews are conducted to analyze learners’ learning strategies and their cognitive performance during the gaming process.     

Construction safety training via e-Learning: Learning effectiveness and user satisfaction

In Taiwan, promoting knowledge of “Labor Safety” which relates to life and work right is very important. Safety training and learning effectiveness become essential issues of adult learning. To reduce the costs of educational training, enterprises have also started to aggressively introduce e-learning education training. Unlike the construction industry, few studies have investigated the effectiveness of e-learning and conventional learning. This study tested the effectiveness of the safety education to prevent falls by different learning modes used to assess safety behavior and learning effectiveness during the education training period. According to the average pass rate, satisfaction degree of course and total number of unsafe behavior, the e-learning mode improves learning effectiveness. Additionally, when the e-learning mode is introduced in the construction safety education training, the labor can use the teaching material more independently and multimedia system, such as animated teaching materials, case teaching, and repeated course learning, to reduce the error rate of operation, property loss rate, and light (heavy) injury. Under this condition, the e-learning mode is positively associated with the learning effectiveness of construction safety education training. High learning effectiveness promotes safe behavior during construction operations.     

高校多媒体网络教室的病毒防治

本文针对高校多媒体网络教室面临的计算机病毒、网络攻击等安全问题,首先分析了病毒的传播途径,然后探讨了计算机病毒防治的方法,从技术上和管理等方面有的放矢地采取安全防治对策,为师生创造安全的实验教学环境。     

基于文图转换的维吾尔文彩信技术研究与实现

以维吾尔文MMS(Multimedia Messaging Service)技术研究为背景,结合维吾尔文的书写特点和风格,通过调研现有手机MMS技术方案,分析了开发维吾尔文彩信业务的技术难点,研究了一种基于文图转换的维吾尔文彩信技术实施方案,提供了一种文图转换算法,并通过研究MMS消息封装,SMIL语言对消息的组装,生成了维吾尔文MMS,在Nokia 5100模拟器中验证了本研究方案的有效性和可行性。     

Learning science via animated movies: Its effect on students’ thinking and motivation

Some researchers claim that animations may hinder students’ meaningful learning or evoke misunderstandings. In order to examine these assertions, our study investigated the effect of animated movies on students’ learning outcomes and motivation to learn. Applying the quantitative methodology, two pre- and post-questionnaires were administered: Science thinking skills and Motivation to learn science. Students’ overall achievement in science was examined by their report card scores. The research population (N = 1335) was divided into experimental (N = 926) and control (N = 409) groups from 11 elementary schools. Findings indicated that the use of animated movies promoted students’ explanation ability and their understanding of scientific concepts. Findings also indicated that students who studied science with the use of animated movies developed higher motivation to learn science, in terms of: self-efficacy, interest and enjoyment, connection to daily life, and importance to their future, compared to the control students. Following the definition of multimedia, the students who study with the use of animated movies, applied all three learning styles: visual, auditory and kinesthetic. The use of multimedia and the fact that the students were engaged in exploring new concepts, that were relevant to their daily life experiences, can explain the positive results.     

Incorporating haptic feedback in simulation for learning physics

The purpose of this study was to investigate the effectiveness of a haptic augmented simulation in learning physics. The results indicate that haptic augmented simulations, both the force and kinesthetic and the purely kinesthetic simulations, were more effective than the equivalent non-haptic simulation in providing perceptual experiences and helping elementary students create multimodal representations of the movements of gears. However, in most cases, force feedback was needed to construct a fully loaded multimodal representation that helps students to comprehend later instruction with less sensory modalities. In addition, the force and kinesthetic simulation was effective in helping to transfer knowledge to new learning situations. These findings suggest that it is important to help elementary students make a solid cognitive grounding with the use of a perceptual anchor.