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1.
Sensitivity analysis is a mathematical tool, first developed for optimization methods, which aim is to characterize a system response through the variations of its output parameters following modifications imposed on the input parameters of the system. Such an analysis may quickly become laborious when the thermal model under consideration is complex or the number of input parameters is high. In this paper, we develop a mathematical model to analyse the heat exchanges in four different types of solar air collectors. When building this thermal model we show that for each collector, at quasi-steady state, the energy balance equations of the components of the collector cascade into a single first-order non-linear differential equation that is able to predict the thermal behaviour of the collector. Our heat transfer model clearly demonstrates the existence of an important dimensionless parameter, referred to as the thermal performance factor of the collector, that compares the useful thermal energy which can be extracted from the heater to the overall thermal losses of that collector for a given set of input parameters. A sensitivity analysis of our thermal model has been performed for the most significant input parameters such as the incident solar irradiation, the inlet fluid temperature, the air mass flow rate, the depth of the fluid channel, the number and nature of the transparent covers in order to measure the impact of each of these parameters on our model. An important result which can be drawn from this study is that the heat transfer model developed is robust enough to be used for thermal design studies of most known flat plate solar air heaters, but also of flat plate solar water collectors and linear solar concentrators. 相似文献
2.
The quantum states are presented in these processions of fabricating poly-Si films. Amorphous silicon films prepared by PECVD has been crystallized by conventional furnace annealing (FA) and rapid thermal annealing (RTA), respectively. It is found that the thin films grain size present quantum states with the increasing of the gas flow ratios of SiH4, H2 mixture, substrate temperatures, frequency power, annealing temperature and time. 相似文献
3.
Lubomir Spanhel 《Journal of Sol-Gel Science and Technology》2006,39(1):7-24
The past research work devoted to ZnO nanocolloidal sol-gel route is reviewed. It highlights the cluster chemistry of alcoholic
ZnAc2 solutions and the results of ZnO colloid growth investigations performed worldwide. Moreover, the role of doping and co-doping
in the processing of functional ZnO coatings is discussed. The possibilities of tuning the optical properties are also reported
with a particular attention to luminescence. The last part of this paper deals with electrical and photoelectrochemical properties
of ZnO nanocrystals and their aggregates.
This contribution is dedicated to the 80th birthday of Prof. Arnim Henglein from the Hahn-Meitner-Institut in Berlin and to
the memory of Prof. Jacques Mugnier from the Université Claude-Bernard Lyon 1 in France. 相似文献
4.
关新民 《新疆大学学报(理工版)》2002,19(1):95-99
介绍了采用MATLAB V5.2提供的模糊逻辑工具箱来设计研究电孤纺电极调节系统中的模糊--PD控制器,讨论了在SIMULINK环境下模糊-PD控制器的参数自调速原理、结构、建立模糊控制规则库和模糊推论方法,并给出仿真结果与结论。 相似文献
5.
R. Bairava Ganesh Hitoshi Matsuo Takahiro Kawamura Yoshihiro Kangawa Koji Arafune Yoshio Ohshita Masafumi Yamaguchi Koichi Kakimoto 《Journal of Crystal Growth》2008,310(11):2697-2701
Multicrystalline silicon was grown by unidirectional solidification method using the accelerated crucible rotation technique. The application of the accelerated crucible rotation technique in unidirectional solidification method induced growth striations across the axial direction of the grown crystal. This striation pattern was observed from carbon concentration distribution, obtained by using Fourier transform infrared spectroscopy. The generated striation pattern was found to be weak and discontinuous. Some striations were absent, probably due to back melting, caused during each crucible rotation. From the growth striations and applied time period in crucible rotation, the growth rate was estimated by using Fourier transformation analysis. 相似文献
6.
7.
B. Bavassano 《Il Nuovo Cimento C》1992,15(5):501-508
Summary A study has been promoted by NASA to evaluate the scientific return and the technological problems of a close-to-the-Sun mission
(Solar Probe). It has come out that using current technology it is possible to deliver at 4 solar radii from the Sun's centre
a scientific payload with such performances to allow a great improvement of our understanding of the coronal phenomena. The
mission concept currently under study uses planetary encounters to reach the required orbit. The final orbit period is 2.5
years, the estimated mission duration about 9 years. The orbit inclination is such as to give the maximum coverage in terms
of heliographic latitude. During the perihelion phases a conical structure shields the spacecraft from the intense solar radiation.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
8.
在过氧化氢溶液及硝酸镍存在下,用石墨炉原子吸收法测定化妆品中砷的含量,砷的浓度在0-1mg/L时与吸光度线相关,线性方程为A=0.838c 0.003,相关系数为0.99994。对液体和固体化妆品中的砷进行测定,砷的加标回收率为98.3%-98.7%,测定结果的相对标准偏差为0.65%-1.50%。 相似文献
9.
A new method based on anion exchange resin separation and graphite furnace atomic absorption spectrometry (GFAAS) detection
is proposed for the determination of inorganic tin species. The result showed that Sn(IV) was quantitatively retained on the
resin when [HCl] = 9.0 mol · L−1, but Sn(II) could not be adsorbed on the resin under the same condition. Thus, a separation of Sn(II) and Sn(IV) has been
realized. When the concentration of NaOH solution was between 2.0–7.0 mol · L−1, Sn(IV) that adsorbed on the resin could be eluated from the resin completely. Meanwhile, under the atmosphere and the nitrogen
states, the translation between Sn(II) and Sn(IV) was investigated. Under the optimal conditions, the detection limit of Sn(IV)
is 0.40 μg · L−1 with RSD of 2.3% (n = 5, c = 2.0 μg · L−1). The proposed method was applied to the speciation analysis of tin in different water samples and the recovery of total
Sn was in the range of 98.7–101.7%. In order to verify the accuracy of the method, a certified reference water sample was
analyzed and the results obtained were in good agreement with the certified value. 相似文献
10.
Summary The radial evolution of Alfvénic correlation is such that its value decreases with increasing heliocentric distance. So far
this behaviour has been interpreted as an increase in the local production of ?inward? modes interacting destructively with
the ?outward? modes. This work, which deals with largescale turbulence, shows that local generation phenomena are not commonly
found in the solar wind and that the Alfvénic character of the fluctuations mainly depend on the ?outward? modes alone. The
interaction of these modes with density and/or magnetic-field structures convected by the wind causes their destruction and
a consequent depletion of the Alfvénic correlation. The same effect would be obtained if ?inward? modes were really present.
Our conclusions are that large-scale ?inward? modes are the spectral counterpart of non-propagating field and plasma structures
convected by the solar wind and identified as both compression regions and pressure balance structures.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献