Analyzing Online Sentiment to Predict Telephone Poll Results

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Large-eddy simulation of turbulent flows and pollutant transport inside and above idealized urban street canyons under different unstable thermal stratification

Large-eddy simulation (LES) is employed to study the behaviours of flows and pollutant transport inside and over idealized urban street canyons under different unstable thermal stratification. Three configurations of idealized street canyon, consisting of building-height-to-street-width (aspect) ratios, 0.5, 1 and 2, are considered. Under unstable stratification, the vertical profiles of streamwise velocity and temperature over the bottom rough surface are more uniform and the turbulent transport of momentum and heat are enhanced. Inside the street canyons, the ventilation performance, which are characterized by the air exchange rate (ACH), pollutant exchange rate (PCH), pollutant retention time and average pollutant concentration, is found improved in unstable stratification.postprin

Reverse-play technique on compressed video across GOP boundaries

Centre for Signal Processing, Department of Electronic and Information EngineeringRefereed conference paper2007-2008 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Development of the vestibular system

This review mainly focuses on the development of the vestibular system in humans and other mammals, but reference is made to anurans and other species where applicable. In the first section, the steps involved in the development of undifferentiated cells into mature vestibular receptors are analysed. Available data indicate that in humans, maturation of the vestibular receptor and its afferent innervations involves a similar sequence of events as in other mammalian species. In the second section, morphological and physiological aspects of the maturation of the central vestibular system are presented. Undifferentiated neuron precursors have been identified in specific segregrated domains of the hindbrain neural tube, and these can develop into secondary vestibular neurons with unique properties. Several neuronal populations in the vestibulospinal and vestibulo-ocular pathways have been found to correlate with rhombomeric domains at early embryonic stages. In rodents, the vestibular system continues to develop postnatally in terms of morphology and function until it achieves its final form. The postnatal changes in the properties of vestibular nuclear neurons are chronologically matched with structural changes and serve to prime the development of vestibular-induced reflexes. Copyright © 2002 S. Karger AG, Basel.published_or_final_versio

Interleaved boost power factor corrector operating in discontinuous-inductor-current mode

This paper presents the basic operation of the Discontinuous-Inductor-Current-Mode (DICM) boost PFC and the improvement achieved by interleaving technique. The PFC is constructed by at least two boost cells, each cell is kept running in DICM. Input current of the PFC is analyzed by numerical method and the optimum power factor is calculated in different modes of operation. The calculated result is verified by experiment and presented in graphical form with detailed discussion. The result shows that interleaving technique can alleviate the ripple current and improve the power factor. The improvement is obvious for the number of boost cells equal to 2 or 3 and the ripple alleviation is better when the PFC is operated in fixed frequency mode. The optimum power factor is improved up to 0.99 even without an input filter.published_or_final_versio

Fast response Full Bridge Power Factor Corrector

A fast response Full Bridge Power Factor Corrector (FBPFC) is presented in this paper. The converter is combined by two interleaved boost cells and a conventional full bridge converter. As the interleaving technique is applied, the input ripple current of FBPFC are reduced. Experimental result shows that the maximum power factor is 0.98 even without input filter.published_or_final_versio

Networked collective action in the 2014 Hong Kong Occupy Movement: analysing a Facebook sharing network

Using a “big data” approach, this study aims to demonstrate and analyse the way in which the formation of an online network, i.e. posts sharing between Facebook pages, help construct a countervailing power during the course of the Hong Kong Occupy Movement (or called “Umbrella Movement”), which protested against the electoral reform framework imposed by the Standing Committee, China’s National People’s Congress in relation to the implementation of universal suffrage for the 2017 Hong Kong Chief Executive election. The result indicates an empowerment of emerging civil society in the venue of policy debate, whereas there was a disintegration between institutional political forces and the civil society. This may not be conductive to an institutionalized policy formation involving a variety of stakeholders amid the controversy.postprin

Fabric defect detection by Fourier analysis

Many fabric defects are very small and undistinguishable, which are very difficult to detect by only monitoring the intensity change. Faultless fabric is a repetitive and regular global texture and Fourier transform can be applied to monitor the spatial frequency spectrum of a fabric. When a defect occurs in fabric, its regular structure is changed so that the corresponding intensity at some specific positions of the frequency spectrum would change. However, the three-dimensional frequency spectrum is very difficult to analyze. In this paper, a simulated fabric model is used to understand the relationship between the fabric structure in the image space and in the frequency space. Based on the three-dimensional frequency spectrum, two significant spectrum diagrams are defined and used for analyzing the fabric defect. These two diagrams are called the central spatial frequency spectrums. The defects are broadly classified into four classes: (1) double yarn; (2) missing yarn; (3) webs or broken fabric; and (4) yarn densities variation. After evaluating these four classes of defects using some simulated models and real samples, seven characteristic parameters for central spatial frequency spectrum are extracted for defect classification.published_or_final_versio

Numerical modeling of flows and pollutant dispersion within and above urban street canyons under unstable thermal stratification by large-eddy simulation

Recently, with the ever increasing urban areas in developing countries, the problem of air pollution due to vehicular exhaust arouses the concern of different groups of people. Understanding how different factors, such as urban morphology, meteorological conditions and human activities, affect the characteristics of street canyon ventilation, pollutant dispersion above urban areas and pollutant re-entrainment from the shear layer can help us improve air pollution control strategies. Among the factors mentioned above, thermal stratification is a significant one determining the pollutant transport behaviors in certain situation, e.g. when the urban surface is heated by strong solar radiation, which, however, is still not widely explored. The objective of this study is to gain an in-depth understanding of the effects of unstable thermal stratification on the flows and pollutant dispersion within and above urban street canyons through numerical modeling using large-...published_or_final_versio

Fabric defect detection by Fourier analysis

Many fabric defects are very small and undistinguishable, which are very difficult to detect by only monitoring the intensity change. Faultless fabric is a repetitive and regular global texture and Fourier transform can be applied to monitor the spatial frequency spectrum of a fabric. When a defect occurs in fabric, its regular structure is changed so that the corresponding intensity at some specific positions of the frequency spectrum would change. However, the three-dimensional frequency spectrum is very difficult to analyze. In this paper, a simulated fabric model is used to understand the relationship between the fabric structure in the image space and in the frequency space. Based on the three-dimensional frequency spectrum, two significant spectrum diagrams are defined and used for analyzing the fabric defect. These two diagrams are called the central spatial frequency spectrums. The defects are broadly classified into four classes: (1) double yarn; (2) missing yarn; (3) webs or broken fabric; and (4) yarn densities variation. After evaluating these four classes of defects using some simulated models and real samples, seven characteristic parameters for central spatial frequency spectrum are extracted for defect classification.published_or_final_versio