Creating Language: A Learning Curve in Material Development

本文は、新たな教授法の導入に関する情報を提供する。著者は、言語学習教材の質および焦点に物足りなさを感じた経緯から、試行錯誤を重ね、ハリデーの機能文法ならびに一連のスキャフォールディング（足場づくり）による支援された’guided writing（予め方向付けされたライティング練習）’を取り込んだコースを開始した。このコースは、大学での言語教育に必要とされるスキルを習得し使うこと、過去の言語学習を発展させること、ならびに自律学習に向けた十分な指導をすることを3 年の間にさまざまなバージョンが作成されたが、ここではどのような段階を経て、どのような問題に遭遇したかを取り上げる。学生からのフィードバックの反映、アクティビティの数および多様性の増加、’guided writing’の導入、学生への教材の提示方法の変更、ならびに文章のジャンルによる違いなど、時間の経過とともに変更・調整を重ねた。この結果としてできたコースをCreating Language と呼ぶ。本コースの学生は、常時、特定のリサーチトピックへと方向づけられ、クラスメートや講師との振り返りおよびディスカッションを通じて、深いレベルで教材に関わるよう奨励される。コース終了時には、今後もこの手法を継続して使用、発展させていくための十分な手ごたえがあった。This paper examines the development of new academic teaching materials in a university context. The materials include explicit reference to Hallidayan functional grammar and make strong use of the Vygotskian concept of scaffolding.Several versions of the course illustrate the problems encountered and the modifications made over a period of three years. During this time, adjustments to the course, with reference to feedback from students, included the number and variety of activities, the introduction of scaffolded guided writing paragraphs, material presentation methods, and the utilisation of selected text types. The resulting course was named ‘Creating Language’. Throughout the course, students were guided towards specific research topics and encouraged to engage material at a deeper level through the use of taxonomies, reflection, and discussion with peers.By the end of the study period, it was strongly believed that the course had the potential to encourage a significant improvement in student language competence

Health impacts from diesel freight emissions: Development of a geospatial analytical framework for policy evaluation with a case study of Sacramento, CA

Diesel particulate matter, emitted by many types of freight transport, poses a health risk to populations living near freight activity. Accurate information about the magnitude and location of health impacts would help inform policy decisions at a number of levels. Existing methods, including atmospheric dispersion modeling, epidemiology or air quality measurement can estimate the magnitude of harm experienced by populations but these methods often require resources or expertise beyond the reach of some stakeholders, particularly those at local levels. This thesis describes a framework by which health impact estimation can be carried out utilizing readily available models and methodologies in a more simple fashion. This framework postulates that significant parts of the analytic process can be automated by computer scripts or other programmatic structures, thereby reducing the time, expertise and resource requirements for health impact analyses. These analyses will allow policy makers to more effectively evaluate the expected health impacts of transport policy and incorporate public health considerations into other policy making activities. This thesis assembles the analytic tools required for these analyses and outlines the ways in which they might be joined into a single piece of software; though the actual creation of this software is left to future work. A case study of on-highway truck activity in Sacramento, CA utilizes this analytic framework. This case study demonstrates framework and also highlights some possible policy directions for transport in the region

Evaluation of automatic shot boundary detection on a large video test suite

The challenge facing the indexing of digital video information in order to support browsing and retrieval by users, is to design systems that can accurately and automatically process large amounts of heterogeneous video. The segmentation of video material into shots and scenes is the basic operation in the analysis of video content. This paper presents a detailed evaluation of a histogram-based shot cut detector based on eight hours of TV broadcast video. Our observations are that the selection of similarity thresholds for determining shot boundaries in such broadcast video is difficult and necessitates the development of systems that employ adaptive thresholding in order to address the huge variation of characteristics prevalent in TV broadcast video

Voting rule optimisation for double threshold energy detector-based cognitive radio networks

The method by which individual decisions are combined in cooperative cognitive radio networks is crucial to minimising the overall probabilities of false alarm and missed detection. In this paper, general expressions for these probabilities are derived for a double threshold energy detector-based network, and an analytical solution for the optimal value of voting rule is found so that the overall probability of error is minimised. Simulation results show that there are significant advantages to the use of double threshold energy detector-based networks as opposed to their single threshold-based counterparts; additional simulations verify that the analytical solution is optimal

Implementation issues for optimized hard decision energy detector-based cooperative spectrum sensing

Recent studies in cooperative energy detection have focused on the optimization of the threshold value and fusion center voting rule in an effort to minimize the sensing error probability. However, such studies operate under the assumption that the signal to noise ratio is equal at every node, which is rarely the case in practice. In this paper, generalized formulas for the optimal threshold value and optimal fusion center voting rule are derived for hard decision energy detector-based spectrum sensing networks where the signal to noise ratio is distinct at each node. It is shown that the implementation of this solution requires more data to be transmitted than the optimal soft decision scheme, which is known to have superior performance

Fast and accurate approximations for the analysis of energy detection in Nakagami-m channels

Previous research has identified several exact methods for the evaluation of the probability of detection for energy detectors operating on Nakagami-m faded channels. However, these methods rely on discrete summations of complicated functions, and so can take a prohibitively long time to evaluate. In this paper, three approximation for the probability of detection in Nakagami-m faded channels, having distinct regions of applicability, are derived. All have closed forms, and enable the fast and accurate computation of key performance metrics

On the convergence of the chi square and noncentral chi square distributions to the normal distribution

A simple and novel asymptotic bound for the maximum error resulting from the use of the central limit theorem to approximate the distribution of chi square and noncentral chi square random variables is derived. The bound enables the quick calculation of the number of degrees of freedom required to ensure a given approximation error, and is significantly tighter than bounds derived using the Berry-Esseen theorem. An application to widely-used approximations for the decision probabilities of energy detectors is also provided

Performance limits of cooperative energy detection in fading environments

In this paper, the performance of energy detector-based spectrum sensor networks is examined under the constraints of the IEEE 802.22 draft specification. Additive white Gaussian noise (AWGN) channels are first considered, and a closed form solution for sample complexity is derived for networks of any size. Rayleigh, Nakagami and Rice fading channel models are also examined, with numerical results demonstrating the effect of these models on the required sample complexity for varying numbers of cooperating nodes. Based on these results, the relationship between the sample complexity for AWGN, Rayleigh and Nakagami channels is examined. Through data fitting, an approximate model is derived, allowing the sample complexity for Rayleigh and Nakagami channels to be computed easily. The model is shown to be accurate across a range of practical values

The Físchlár digital video recording, analysis, and browsing system

In digital video indexing research area an important technique is called shot boundary detection which automatically segments long video material into camera shots using content-based analysis of video. We have been working on developing various shot boundary detection and representative frame selection techniques to automatically index encoded video stream and provide the end users with video browsing/navigation feature. In this paper we describe a demonstrator digital video system that allows the user to record a TV broadcast programme to MPEG-1 file format and to easily browse and playback the file content online. The system incorporates the shot boundary detection and representative frame selection techniques we have developed and has become a full-featured digital video system that not only demonstrates any further techniques we will develop, but also obtains users’ video browsing behaviour. At the moment the system has a real-user base of about a hundred people and we are closely monitoring how they use the video browsing/navigation feature which the system provides