Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
For the OFDM-based Amplify-and-Forward cooperative system, a novel relay-superimposed pilot strategy is proposed, where the\nsource pilot symbols are frequency divisionmultiplexed to estimate the cascaded channelwhile relay pilot sequence is superimposed\nonto the top of the cooperative data streamfor second-hop channel estimation. This method avoids the loss of data rate for additional\npilot subcarriers but results in the interference of unknown cooperative data. To remove the interference of cooperative data during\nthe estimation of second-hop channel, the Cooperative Interference Cancelation scheme assisted by cooperative data from direct\nlink is proposed.We derive the approximated lower bound for the MSE of second-hop channel estimation. Simulation results are\npresented to validate the performance of the proposed schemes....
We have investigated the efficacy of on-line, multimedia learning modules (MLMs)\nas preparation for in-class, lecture-based tutorials in electromagnetism in a physics course for\nnatural science majors (biology and marine science). Specifically, we report the results of a\nmultiple-group pre/post-test research design comparing two groups receiving different treatments\nwith respect to activities preceding participation in Tutorials in Introductory Physics. The different\npre-tutorial activities were as follows: (1) students were assigned reading from a traditional textbook,\nfollowed by a traditional lecture; and (2) students completed on-line MLMs developed by the\nPhysics Education Research Group at the University of Illinois at Urbana Champaign (UIUC),\nand commercially known as FlipItPhysics. The MLM treatment group earned significantly higher\nmid-term examination scores and larger gains in content knowledge as measured by the Conceptual\nSurvey of Electricity and Magnetism (CSEM). Student attitudes towards ââ?¬Å?reformedââ?¬Â instruction in the\nform of active-engagement tutorials were also improved. Specifically, post-course surveys showed\nthat MLM-group students believed class time was more effective and the instructor was more clear\nthan reported by non-MLM students, even though there was no significant difference between groups\nwith respect to in-class activities and the same instructor taught both groups. MLM activities can be a\nhighly effective tool for some student populations, especially when student preparation and buy-in\nare important for realizing significant gains....
Energy efficiency and delay optimization are significant for the proliferation of wireless multimedia sensor network (WMSN). In\nthis article, an energy-efficient, delay-efficient, hardware and software cooptimization platformis researched to minimize the energy\ncost while guaranteeing the deadline of the real-time WMSN tasks. First, a multicore reconfigurable WMSN hardware platform\nis designed and implemented. This platform uses both the heterogeneous multicore architecture and the dynamic voltage and\nfrequency scaling (DVFS) technique. By this means, the nodes can adjust the hardware characteristics dynamically in terms of the\nsoftware run-time contexts. Consequently, the software can be executedmore efficiently with less energy cost and shorter execution\ntime. Then, based on this hardware platform, an energy and delay multiobjective optimization algorithm and a DVFS adaption\nalgorithm are investigated. These algorithms aim to search out the global energy optimization solution within the acceptable\ncalculation time and strip the time redundancy in the task executing process. Thus, the energy efficiency of the WMSN node\ncan be improved significantly even under strict constraint of the execution time. Simulation and real-world experiments proved\nthat the proposed approaches can decrease the energy cost by more than 29% compared to the traditional single-coreWMSN node.\nMoreover, the node can react quickly to the time-sensitive events....
Organisations such as hospitals and the public are increasingly relying on large computer\nnetworks to access information and to communicate multimedia-type data. To assess the effectiveness\nof these networks, the traffic parameters need to be analysed. Due to the quantity of the data\npackets, examining each packet�s transmission parameters is not practical, especially in real time.\nSampling techniques allow a subset of packets that accurately represents the original traffic to be\nexamined and they are thus important in evaluating the performance of multimedia networks.\nIn this study, an adaptive sampling technique based on regression and a fuzzy inference system was\ndeveloped. The technique dynamically updates the number of packets sampled by responding to\nthe traffic�s variations. Its performance was found to be superior to the conventional nonadaptive\nsampling methods....
Nowadays, the math learning is an important step in developing professional\ncarriers in technical and economic sciences. Increasing the number of e-learning tools used\nin universities courses can reduce the potential barrier of access to mathematical knowledge,\nbut most of them are not accessible for impaired students. Moreover, classical printed math\nbooks include little explicit instructional information about structural information interpretations.\nTaking into account these barriers the article presents the developed method used for\ncreating interactive steps of decomposed math�s exercise solution and alternative description of\nmath formulas accessible for the blind. The elements of proposed methodology: generation of\nstate machine, design and presentation of transition conditions, generating the presentation\nlayer and a typical usage by a blind user are presented. A set of rules for describing\nmathematical formulas were proposed after consultation with mathematicians and teachers\nof blind people. The application was developed as web application. The graphical interface of\npresented application was designed using PHP and JavaScript technologies. The collection of\nprepared exercises include about 240 prepared exercises from different areas of mathematics and 60 selected exercises including alternative description layer. About 1000 students and\nabout 40 impaired students, from 6 faculties of the university use this platform during math\ncourses for both self and class learning. The defined rules were used to read aloud mathematical\nformulas to the visually impaired people with a different level of mathematical knowledge.\nThe results confirmed good understanding of mathematical formulas by using prepared\nalternative description....
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