Flow and Acoustic Properties of Low Reynolds Number Underexpanded Supersonic Jets

Jet noise on underexpanded supersonic jets are studied with emphasis on determining the role played by large scale organized flow fluctuations in the flow and acoustic processes. The experimental conditions of the study were chosen as low Reynolds number (Re=8,000) Mach 1.4 and 2.1, and moderate Reynolds number (Re=68,000) Mach 1.6 underexpanded supersonic jets exhausting from convergent nozzles. At these chosen conditions, detailed experimental measurements were performed to improve the understanding of the flow and acoustic properties of underexpanded supersonic jets

Rethinking washback: The interplay of beliefs and contextual factors to mediate pedagogy

This study addresses issues of English as a foreign language (EFL) practice in the attainment-oriented context at the tertiary level. Referring to the widespread use of testing as an instrument for the enhancement of teaching quality, the study stresses the importance of teachers’ epistemological beliefs and other contextual factors to mediate teacher’s pedagogical decision-making. Four EFL teachers at Air Force colleges in Taiwan were selected to participate in the present research. The EFL teachers’ beliefs were collected by semi-structured interviews, and actual classroom practices were analyzed through a taxonomy of teachers’ questions, a taxonomy of teachers’ corrective feedback and Communicative Orientation Language Teaching (COLT) scheme analysis. The evidence of this case study generated four archetypal patterns of washback based on aligned or oppositional beliefs and its contexts. The study concludes that test designers’ expectations to use a test to innovate the curriculum do not always produce the desired results. Education reform that requires pedagogical changes of practitioners but fails to provide re-attribution training and sufficient resources to effect belief changes will likely yield resistance and pressure. Finally, implications of four archetypes of washback on the teaching of English are presented in order to sustain the successful testing, teaching, and learning

Colors of the music

It is a generation of high technology. Our daily life is full of computing in the aspects of work and leisure. Computing also influences on art, and now a computer can be a new form of representation. Artists use computers to create and show their art works, and viewers now not only view those art works but also involve in art works through the interactivity of a computer. Motion graphics are attractive. Flash based programs are rich in interaction. This project combines the two features to create a user driven art that promotes classical music to children and of course to every one. In such an interactive and attractive way, users enjoy the music and listen to the three world-known songs from Saint Saëns\u27s Carnival of Animals- Royal March of Lion, Aquarium, and the Swan. When the music starts, by clicking the mouse, users can add motion graphics related to the music on a computer screen. It is a problem to figure out a way to generate pixel-based motion graphics with Flash, which usually deals with vector images. First built are the codes, that give this project functions of interaction. Users can choose a song, add motion graphics on a computer screen, pause or play the music, change the volume of the sound, choose different color, and print out images they create. The rest are the motion graphics, that reflect the unique theme of each song. In order to display well, different methods are examined to generate motion graphics, including loading FLV files exported by After Effects, and adding movie clips built in Flash, and more. The result shows that adding movie clips built in Flash is the best way. Other ways result in the pixilated edges of graphics, the difficulty of making alpha movies, or other technical problems. Having the capabilities of enabling users to control the program and displaying motion graphics in high quality, this project performs as a new medium introducing classical music to new generations

Efficient gear fault feature selection based on moth‑flame optimisation in discrete wavelet packet analysis domain

Rotating machinery—a crucial component in modern industry, requires vigilant monitoring such that any potential malfunction of its electromechanical systems can be detected prior to a fatal breakdown. However, identifying faulty signals from a defective rotating machinery is challenging due to complex dynamical behaviour. Therefore, the search for features which best describe the characteristic of different fault conditions is often crucial for condition monitoring of rotating machinery. For this purpose, this study used the intensification and diversification properties of the recently proposed moth-flame optimisation (MFO) algorithm and utilised the algorithm in the proposed feature selection scheme. The proposed method consisted of three parts. First, the vibration signals of gear with different fault conditions were decomposed by a fourth-level discrete wavelet packet transform, and the statistical features at all constructed nodes were derived. Second, the MFO algorithm was utilised to select the optimal discriminative features. Lastly, the MFO-selected features were used as the input for a support vector machine (SVM) diagnostic model to identify fault patterns. To further demonstrate the superiority of the proposed method, other feature selection approaches were applied, including randomly selected features and complete features, and other diagnostic models, namely the multilayer perceptron neural network and k-nearest neighbour. Comparative experiments demonstrated that SVM with the MFO-selected features outperformed the others, with the classification accuracy of 99.60%, thus validating its effectiveness

Noninvasive prediction of Blood Lactate through a machine learning-based approach.

We hypothesized that blood lactate concentration([Lac]blood) is a function of cardiopulmonary variables, exercise intensity and some anthropometric elements during aerobic exercise. This investigation aimed to establish a mathematical model to estimate [Lac]blood noninvasively during constant work rate (CWR) exercise of various intensities. 31 healthy participants were recruited and each underwent 4 cardiopulmonary exercise tests: one incremental and three CWR tests (low: 35% of peak work rate for 15 min, moderate: 60% 10 min and high: 90% 4 min). At the end of each CWR test, venous blood was sampled to determine [Lac]blood. 31 trios of CWR tests were employed to construct the mathematical model, which utilized exponential regression combined with Taylor expansion. Good fitting was achieved when the conditions of low and moderate intensity were put in one model; high-intensity in another. Standard deviation of fitting error in the former condition is 0.52; in the latter is 1.82 mmol/liter. Weighting analysis demonstrated that, besides heart rate, respiratory variables are required in the estimation of [Lac]blood in the model of low/moderate intensity. In conclusion, by measuring noninvasive cardio-respiratory parameters, [Lac]blood during CWR exercise can be determined with good accuracy. This should have application in endurance training and future exercise industry