160 research outputs found
Growth and characterization of cubic InGaN and InGaN/GaN quantum wells
No full textShunfeng LiPaderborn, Univ., Diss., 200
Growth of Cubic GaN by MOCVD at High Temperature
No full textHigh quality cubic GaN (c-GaN) is grown by metalorganic vapor deposition (MOCVD) at an increased growth temperature of 900 ℃, with the growth rate of 1.6 μm/h. The full width at half maximum (FWHM) of room temperature photoluminescence (PL) for the high temperature grown GaN film is 48meV. It is smaller than that of the sample grown at 830 ℃. In X-ray diffraction (XRD) measurement, the high temperature grown GaN shows a (002) peak at 20° with a FWHM of 21'. It can be concluded that, although c-GaN is of metastable phase, high growth temperature is still beneficial to the improvement in its crystal quality. The relationship between the growth rate and growth temperature is also discussed
Mobility of the Chinese Urban Poor - A Case Study of Hefei City
No full textIn a rapid economic development environment with rising income, escalating motorization, and growing urbanization, it is natural for government policies to focus on solving congestion related problems caused by the increased car ownership and usage. The mobility needs of the urban poor have been traditionally neglected in policy and in practice, particularly in developing countries. This paper addresses the mobility challenges the urban poor are facing based on a household travel survey in the City of Hefei in China. It first presents travel behaviors, transportation costs and commuting problems of the urban poor. It then discusses the urban transportation policy implications and examines the prevailing trends of urban transportation policies and plans in Chinese cities. Policy recommendations are suggested to improve the mobility needs of the urban poor.Urban transportation, poverty, mobility
Property Tax in Urban China
No full textThis paper examines the urban housing sector of China and proposes a property tax reform. Over the past decade, housing price in urban China has been increasing dramatically because of strong demand for self-use, investment and speculation. The booming housing market, however, has brought several challenges for further development, such as housing affordability, inequality, and possible housing bubble. One strategy is to reform the current property tax system. Specifically, this paper proposes that China significantly reduces taxes in circulation but levies property tax during possession. Doing so will increase housing affordability because of lower transaction costs, reduce speculation because of higher cost of holding, stabilize fiscal system because of more sustainable tax revenues, and improve the efficiency and fairness of the property tax system because of the implementation of “ability-to-pay” and “who use who pay” principles.Property tax; China
Head responses subjected to frontal translational acceleration loads
No full textIt is important to understand the relationship between impact accelerations and head responses to improve the protection of head against impact loads. This study aims to parametrically investigate the effects of different frontal translational acceleration loading configurations on head responses using a finite element head model. A series of translational accelerations defined by loading curve shape, impact duration and peak magnitude is applied to a head model to simulate different head impact accidents. The effects of loading configurations on the brain tissue-level responses, including intracranial pressure (ICP), von Mises stress (σv) and maximum principal strain (εp), were studied, and the correlations between head injury criterion (HIC) and tissue-level predictors were analysed. It is found that the head responses increase with the increase of peak magnitudes and the acceleration loading curve shape has significant influences on head responses. The largest head responses were observed for the equivalent square shape (ESS) acceleration case. Both the σv and εp responses increase with the increase of impact durations; however, the impact durations do not affect the ICP responses. Based on the thresholds for tissue-level injury predictors, it is found that both ICP-induced and εp-induced head injuries may occur whereas the σv-induced head injury is less likely to occur under translational acceleration loading conditions. For translational acceleration loading, good correlation can be found between HIC and the εp responses; however, the HIC show a significant difference with the ICP responses for the head injury prediction. To improve the accuracy of head injury prediction with considering different injury mechanisms, ICP responses should be considered when HIC and εp responses are applied in head injury analyses.</p
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