Low-cost sensorless control of four-switch, brushless DC motor drive with direct back-EMF detection

We propose a position sensorless control scheme for a four-switch, three-phase brushless DC motor drive, based on the zero crossing point detection of phase back-EMF voltages using newly defined error functions （EFs）. The commutation instants are 30° after detected zero crossing points of the EFs. Developed EFs have greater magnitude rather than phase or line voltages so that the sensorless control can work at a lower speed range. Moreover, EFs have smooth transitions around zero voltage level that reduces the commutation errors. EFs are derived from the filtered terminal voltages Vao and Vbo of two low-pass filters, which are used to eliminate high frequency noises for calculation of the average terminal voltages. The feasibility of the proposed sensorless control is demonstrated by simulation and experimental results.     

Investigating substantive and consequential validity of student ratings of instruction

This study aimed at exploring faculty and student perspectives on student evaluations, as well as identifying their perceptions of the usefulness and appropriateness of the ratings for evaluating teaching effectiveness. More specifically, the study aimed at identifying the consequences, both intended and unintended, of using the evaluations, in addition to better understanding the process students used in responding to evaluations and what use faculty members made of them. Two surveys were developed and placed on the website of the Office of Institutional Research and Assessment. Emails were sent to all students and faculty participating in evaluations soliciting their cooperation and requesting their input. Faculty and student perceptions were compared qualitatively and statistically. Results revealed that students and faculty believe in the effectiveness and usefulness of the system with the need to overcome some negative consequences and biases inherent in its application at the University. Recommendations for system improvement are provided.     

An optimal Fuzzy-logic based frequency control strategy in a high wind penetrated power system

This paper introduces a new load frequency control (LFC) model in the presence of high wind power penetration level. The main issue in a wind-penetrated power system is to maintain the system frequency in a normal operating band which is specified by the given system grid codes. Essentially, the power system equilibrium point changes following a contingency, and in this case, the high penetration of wind farms makes it harder to regain an acceptable system equilibrium points through conventional control applications. In order to overcome the aforesaid problem, a new Fuzzy-logic controller is designed optimally in this paper using the artificial bee colony (ABC) algorithm. In this approach, the ABC algorithm tunes the membership function parameters of the Fuzzy controller to acquire a good-enough performace of the proposed strategy. More importantly, the proposed Fuzzy-logic controller is blessed with robustness, simplicity, and reliability in order to ameliorate the frequency deviation. It is worth saying that the stability analysis is presented in this paper as well as the noise analysis of the proposed method. The research results indicates how effectively wind farm could participate in the system frequency control through inertial control, primary frequency control, and supplementary frequency control.     

Evaluation of tactical training in team handball by means of artificial neural networks

While tactical performance in competition has been analysed extensively, the assessment of training processes of tactical behaviour has rather been neglected in the literature. Therefore, the purpose of this study is to provide a methodology to assess the acquisition and implementation of offensive tactical behaviour in team handball. The use of game analysis software combined with an artificial neural network (ANN) software enabled identifying tactical target patterns from high level junior players based on their positions during offensive actions. These patterns were then trained by an amateur junior handball team (n = 14, 17 (0.5) years)). Following 6 weeks of tactical training an exhibition game was performed where the players were advised to use the target patterns as often as possible. Subsequently, the position data of the game was analysed with an ANN. The test revealed that 58% of the played patterns could be related to the trained target patterns. The similarity between executed patterns and target patterns was assessed by calculating the mean distance between key positions of the players in the game and the target pattern which was 0.49 (0.20) m. In summary, the presented method appears to be a valid instrument to assess tactical training.     

MRI and PET images fusion based on human retina model

The diagnostic potential of brain positron emission tomography (PET) imaging is limited by low spatial resolution. For solving this problem we propose a technique for the fusion of PET and MRI images. This fusion is a trade-off between the spectral information extracted from PET images and the spatial information extracted from high spatial resolution MRI. The proposed method can control this trade-off. To achieve this goal, it is necessary to build a multiscale fusion model, based on the retinal cell photoreceptors model. This paper introduces general prospects of this model, and its application in multispectral medical image fusion. Results showed that the proposed method preserves more spectral features with less spatial distortion. Comparing with hue-intensity-saturation (HIS), discrete wavelet transform (DWT), wavelet-based sharpening and wavelet-à trous transform methods, the best spectral and spatial quality is only achieved simultaneously with the proposed feature-based data fusion method. This method does not require resampling images, which is an advantage over the other methods, and can perform in any aspect ratio between the pixels of MRI and PET images.     

未来的巴基斯坦地质公园——盐岭

盐岭包括六个峡谷,具有出露充分的地质学和古生物学特征,并且交通便利。这些特点吸引了研究者对这个独特地区的地质时代测定方面的浓厚兴趣,开始对寒武纪三叶虫、二叠纪腕足类、三叠系下统菊石、下第三系大型有孔虫和上第三系及第四纪脊椎动物产生的古地理进行了研究调查。在地质学家眼中,这些盐岭峡谷充满着如此美妙的地质遗址,堪称为世界上独特的野外自然历史博物馆,同时也可能被建设为巴基斯坦的一个地质公园。     

Still as divided as ever? Northern Ireland,football and identity 20 years after the Good Friday Agreement

ABSTRACT

The signing of the Belfast-Good Friday Agreement in 1998 was widely welcomed by those that interpreted it as offering Northern Ireland the prospect of a fresh start, free from inter-ethnic violence that had blighted the country for almost 80 years. Soon it began to be seen by some observers as the genesis too of a ‘Northern Irish’ identity, as the community at large came to reconcile themselves to their common lives in Northern Ireland. Sport was also viewed as offering the prospect of adding weight to this sense of a shared journey and governing bodies of sport unquestionably played their parts in supporting a settled political environment where division had previously existed. This article examines the still contested concept of a ‘Northern Irish’ identity and critically reviews its real currency in a divided society, even if sport and, specifically, association football offers renewed hope for something better in the time ahead.     

Measuring attitude towards learning science in Malaysian secondary school context: implications for teaching

ABSTRACT

The aim of education is to ensure a holistic development towards knowledge and well-being. Despite exhaustive effort on embedding twenty-first century skills in science teaching, students show lack of interest to learn and pursue their science careers. This present study has attempted to develop an instrument for measuring attitude towards science learning. The purpose was to ensure valid items were identified to measure all aspects of attitude namely affect, behaviour and cognitive. The study of attitude in science will determine the direction on how teaching strategies can be successful in promoting interest in learning. The study has been underpinned from the theories related to Theory of Reasoned Action, Constructivist learning and Connectivism. Samples from three secondary schools were selected based on proportionate stratified random sampling. 350 samples were targeted to respond to self-constructed questionnaires. Confirmatory Factor Analysis (CFA) was employed to prove the hypothesised 5-factor measurement model. The results have supported a model fit with positive interactions between the factors are evident. The study has proven the theoretical contributions which embark on holistic development of an individual to ensure attitude is moulded. The emotional and spiritual aspects of learning are needed to ensure positive contribution to the social dynamic. In this paper, the discussions are elaborated from the standpoints of theories and practical importance. The results have contributed to a theoretical model of science teaching method.     

Sports tourism does not have to be accompanied by crime: a case for the NFL Super Bowl

The Routine Activities Theory suggests that when there is the presence of a motivated offender, a suitable target, and the absence of a capable guardian, crime has the opportunity to occur. Large sporting events accompanied by massive tourists bring these ingredients of crime together. The purpose of this study is to find out whether the crime rates spike in the host cities during the high tourist month of the Super Bowl. Twenty-four months of crime rates on eight types of crimes were obtained for every American city that has hosted the Super Bowl. Panel Data Analysis is used to test the Hypotheses of this study. The findings do not show a spike in crime rates during the month of Super Bowl for any of the crimes examined in this study. It is in the economic interests of all stakeholders to provide a safe and secure venue free of crimes for sports tourists.     

The effect of content representation design principles on users’ intuitive beliefs and use of e-learning systems

A model is proposed to assess the effect of different content representation design principles on learners’ intuitive beliefs about using e-learning. We hypothesized that the impact of the representation of course contents is mediated by the design principles of alignment, quantity, clarity, simplicity, and affordance, which influence the learner’s intuitive beliefs about using e-learning systems. The model was empirically validated using data collected from a survey administered to university students. This study demonstrates that these design principles are essential predictors of learners’ intuitive beliefs, which in turn directly influence their decisions about using e-learning systems. The findings provide system designers with quasi-quantitative managerial insights into how to motivate users to continue using e-learning systems.