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排序方式: 共有114条查询结果,搜索用时 15 毫秒
1.
Linus Nyiwul 《Clean Technologies and Environmental Policy》2017,19(2):437-450
This paper analyzes the drivers of renewable energy development and consumption in Sub-Sahara African countries for the period, 1980–2011. The fully modified ordinary least squares, dynamic ordinary least squares, and fixed-effects estimation techniques are used to evaluate the statistical significance of the determinants of renewable energy consumption. Results indicate that income has the desired positive, albeit statistically insignificant contribution to renewable energy consumption growth. This indicates that recent economic strength in the region has not been accompanied by increased development and consumption of renewable energy, in contrast to empirical evidence in other developing economies. A review of the possible reasons for this incongruence is presented. Also, increased consumption of renewable energy is associated with heightened concerns for climate change caused by pollutants such as carbon dioxide. Population and industrial expansion are statistically significant determinants of renewable consumption, and oil prices correlate negatively with renewable energy consumption. 相似文献
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This article proposes a wind velocity sensorless hill-climb searching algorithm in the grid-connected field-oriented controlled permanent magnet synchronous generator based wind energy conversion system. The proposed method improves the speed and accuracy of initial tracking. Pseudo-optimum points are used to track the exact optimum points using the power versus speed characteristics of a wind turbine for various wind velocities. This research emphasizes that the pseudo-optimum points using the power versus speed characteristics are always less than and much nearer to the exact optimum points. The small-step forward tracking after pseudo-optimum points improves the accuracy of this algorithm. Moreover, this method improves the tracking speed for various wind velocities. The system used for this research consists of a back-to-back sinusoidal pulse-width modulation converter between the generator and the grid. The performance of the proposed method is analyzed mathematically and verified by simulation using MATLAB/Simulink software (The Mathworks, Natick; Massachusetts, USA). 相似文献
4.
英国的3C环境和国内有很大不同。首先,英国用户对电脑的要求喜好和国内不同。以台式机为例.DIY在英国并不是很流行,花心思装配一台电脑是很多人不愿意去做的。他们重视的是享受到什么服务和附加价值.例如一些店铺举行促销的话有时候买电脑还会送一年宽带。因此英国人买电脑都是以买品牌机为主。 相似文献
5.
This study shows the effects of three different nanofillers on the viscosity properties and fire behavior of a halogen‐free flame retardant system. The original system, based on ethylene‐acrylate copolymer, calcium carbonate, and a silicone elastomer, shows good flame retardant properties. One of the nanofillers, montmorillonite (MMT), significantly increases the viscosity above 250°C, resulting in reduced dripping and decreased heat release rate. The ash residue, however, is very brittle, indicating poor interactions between the MMT and other components of the system. The second nanofiller, sepiolite, shows no improvement on the flame retardant properties of the system. Reduced dripping is observed when a small amount of the third nanofiller, polyhedral oligomeric silsesquioxane, POSS, is incorporated into the system. In this case, high silica content on the surface indicates char formation originating from the POSS. However, an increased heat release is observed when POSS is used in the system. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
6.
Linus M. Perander Zoran D. Zujovic Tom F. Kemp Mark E. Smith James B. Metson 《JOM Journal of the Minerals, Metals and Materials Society》2009,61(11):33-39
Fines in smelter-grade aluminas are recognized as a significant process problem in aluminum smelting. However, understanding
the nature of this fine material and how it impacts the reduction process are less clearly understood. The combination of
new analytical methods such as variable pressure scanning electron microscopy and very high field solid state nuclear magnetic
resonance provide new insights into the phases present and their spatial distribution within aluminas, and suggest how such
fine materials are generated, particularly during calcination in the alumina refinery. 相似文献
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8.
Jayaprakash Sivasamy Teck-Neng Wong Nam-Trung Nguyen Linus Tzu-Hsiang Kao 《Microfluidics and nanofluidics》2011,11(1):1-10
This paper reports the findings of a numerical investigation on the droplet break-up in a microfluidic T-junction. The numerical
flow visualization of the droplet formation process is validated with the experimental flow visualization. From the computational
results, we show that the pressure profile of the dispersed phase and the continuous phase in the squeezing regime changes
as the droplet break-up process proceeds. The assumption taken by other researchers that the dispersed phase pressure profile,
during the droplet formation process at a T-junction, remains constant and only the continuous phase pressure changes according
to the blockage of the channel is proved to be invalid. We provide new insights on the pressure difference between the dispersed
phase and the continuous phase during the droplet break-up process and show that the minimum pressure difference happens at
the last moment of the droplet break-up and not during the second and third stage of the droplet formation mechanism in the
squeezing regime as suggested by other researchers. 相似文献
9.
Oluwafemi J. Caleb Pramod V. Mahajan Marena Manley Umezuruike Linus Opara 《International Journal of Food Science & Technology》2013,48(11):2315-2323
This study evaluated the effects of passive modified atmosphere packaging design parameters as a function of the amount of product (g), temperature (°C) and time (days) on two pomegranate cultivars. Arils (75, 100 and 125 g) were packed in trays, heat sealed with polylid film and stored at 5, 10 and 15 °C for 14 days, and analysed for physicochemical parameters viz headspace gas composition, weight loss, total soluble solids, titratable acidity, pH, anthocyanin, aerobic‐mesophilic bacterial and fungal load (log CFU g?1). At the highest temperature and weight, O2 concentration continuously decreased below the critical limit (2%) after 4 days, while at 5 °C, this lower limit was not reached. Shelf life of arils was limited to 10, 7 and 3 days by fungal growth ≥2 log CFU g?1 at 5, 10 and 15 °C, respectively. Using unsteady‐state equation, a good agreement was found between simulated and experimental gas composition data. 相似文献
10.
在很多人看来,显卡不过是一块板载了很多芯片的PCB罢了,但是你是否想过,一款显卡之所以设计成目前这个样子其实还是有很大的学问,下面就让我们一起去深入了解显卡……[编者按] 相似文献