ISSN 0253-2778

CN 34-1054/N

2013 Vol. 43, No. 5

Display Method:
Research on the resolution enhancement of brightness temperature at TMI 107 GHz
GAO Yue, LIU Qi, FU Yunfei, HENG Zhiwei, XIAN Tao
2013, 43(5): 345-354. doi: 10.3969/j.issn.0253-2778.2013.05.001
The relatively coarser spatial resolution of low frequency channels of passive microwave remote sensing tends to cause the beam-filling effect,which essentially affects the retrieval of atmospheric parameters and efficiency of usage. With the TMI 107 GHz measurements as the target, discussions were conducted on how to effectively enhance the data resolution of microwave low frequency channels. Firstly, nearest neighbor interpolation, inverse distance weighted and moving least-squares were analyzed separately based on the spatial resolution (about 5 km) of the vertical polarization channel at TMI 855 GHz. Results show that the best method for self-verification is moving least-squares, followed by inverse distance weighted, and the worst one is nearest neighbor interpolation. Then, three typical areas of ocean (170°E~180°E, 10°N~20°N), land (110°W~100°W, 29°N~38°N) and costal regions (140°E~150°E, 13°S~3°S) were chosen for matching resolution at TMI 107 GHz and 855 GHz. Finally, an application to a typhoon case was put forward. This study provides a basis for enhancing the coarse resolution at TMI low frequencies to a fine one at 855 GHz, and for producing a set of multichannel passive microwave data with fine calculated resolution.
Geochemical characteristics of REE in limestone of the Taiyuan Formation, Paner coalmine and their constraint on depositional environment
WU Bin, WU Dun, WAN Zongqi, LIU Guijian, SUN Ruoyu
2013, 43(5): 355-362. doi: 10.3969/j.issn.0253-2778.2013.05.002
Based on a detailed petrologic study, the characteristics of REEs in limestone samples from the Late Carboniferous Epoch Taiyuan Formation in the Huainan Paner coalmine were analyzed. The origin of REEs and the depositional environment of limestone were investigated. Lower concentrations of Zr, Th, Sc, and relatively higher ratios of Y/Ho show that the limestone sediments deposited in a marine environment, with no impact on terrigenous detrital. The characteristics of LREE-depletion, slightly positive La anomaly, positive Y anomaly and high ratio of Y/Ho show that the limestones have similar tendency as the marine carbonate, which indicates that the limestone deposited in a marine environment. However, the Ce anomaly in the limestone samples reflects a transition process of a reducing-oxidizing environment during the deposition. The positive Eu anomaly reflects that the limestone from Taiyuan Formation was formed in a near coastal environment with the input of weathered terrestrial organic matter.
Image fusion quality assessment of multisource remote sensing for TH-1 PAN
ZHU Qian, LI Xia, LIU Lingling
2013, 43(5): 363-368. doi: 10.3969/j.issn.0253-2778.2013.05.003
In order to find suitable multispectral images and fusion methods for the pan-sharpening of TH-1 panchromatic images, IHS, Wavelet, PCA, P+XS, Brovey five transformation methods were used to separately fuse TH-1 PAN with TH-1 MS, TM MS and ETM MS, and the fusion results were assessed from visual and quantitative aspects. Results show that TH-1 PAN and TH-1 MS fusion combination have the best quality; Wavelet transformation can keep the best spectral information, P+XS and Wavelet transformation can keep the best spatial information, and Brovey and IHS can get the best overall quality.
Experimental and theoretical investigation of the superhalogen character of BO2 cluster
FENG Yuan, XU Hongguang, HOU Gaolei, KONG Xiangyu
2013, 43(5): 369-378. doi: 10.3969/j.issn.0253-2778.2013.05.004
Superhalogens exhibit special stable characters and electronic properties, and are suitable to be used as building blocks in designing cluster assembling materials. BO2 is only one electron short to electronic shell closing and has a high electron affinity, 446 eV, larger than that of halogen atoms, so BO2 can be considered as a superhalogen. In order to confirm this, the interactions between BO2 and Cu, Na atoms as well as microscopic salvation of NaBO2 cluster were intensively studied through anion photoelectron spectroscopy (PES) and density functional theory (DFT) calculation. The studies show that BO2 moiety still retains its linear structure as the bare BO2 cluster and behaves as a superhalogen. On the other hand, the microscopic solvation of NaBO2 in water is similar to that of halogen salts. NaBO2 appears as contact ion pair (CIP) structure at first, and then there is a significant change in the photoelectron spectra of NaBO2-(H2O)n clusters starting from n=3, corresponding to the transition from contact ion pair (CIP) structure to solvent-separated ion pair (SSIP) structure. Besides, with an electron affinity of 507 eV, which is larger than that of its BO2 superhalogen building-block, Cu(BO2)2 can be classified as a hyperhalogen. Since the hyperhalogen contains three different elements, it has much more freedom in designing materials.
Theoretical study on the properties of TEMPO and its derivates losing an electron
MAO Shucai, SHU Xugang, SHEN Yong
2013, 43(5): 379-386. doi: 10.3969/j.issn.0253-2778.2013.05.005
A theoretical study on the properties of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and its derivates and each molecule losing an electron in vacuum and in acetonitrile were carried out using the density functional theory (DFT) at the (U)B3LYP/6-31g(d,p) level. The computational results show that different substituents obviously influence the second highest occupied molecular orbitals and the lowest unoccupied molecular orbitals, but the singly occupied molecular orbitals (SOMO) are similar and keep almost unchanged after each molecule losing an electron. Grouping the derivates by the linking atoms(O, N, C) of substituents shows the orderliness: in each group, with the reduction of electron withdrawing ability, the difference of the spin densities on O1 and N2 decreases, while the positive charge population of N2, the negative charge population of O1, bond length of O1—N2 and the energy of SOMO increase. After losing an electron O1—N2 shows obvious double bond properties and above half positive charge increases on O1 and N2. Through the analysis of the open-circuit voltage (VOC) of dye-sensitized solar cells using the derivates as redox mediator, it was found that the VOC were in linear correlation with SOMO levels and vertical ionization potentials.
A heat transfer empirical correlation for the stratospheric airship based on its length-to-diameter ratio
LIU Quan, XU Shumin, ZHONG Wei, YANG Jianzhi, LIU Minghou
2013, 43(5): 387-392. doi: 10.3969/j.issn.0253-2778.2013.05.006
Thermal control is one of the key technologies involved in stratospheric airship applications, and convective heat transfer is an important factor in the thermal control of a stratospheric airship. In order to accurately predict the heat transfer of an airship,using the numerical method, an empirical correlation of Nu number as a function of Re, Pr and l/d (length to diameter ratio) was established. Compared with experimental data, the uncertainty of the empirical correlation is about ±7%. The effect of the attack angle of an airship on heat transfer performance was evaluated. It was found that the heat transfer at the windward side is 10% higher than that of the leeward side, while the average heat transfer of airship is 7% higher when the attack angle changes from 0° to 15°.
Experimental study on flat loop heat pipes used in HCPV systems
ZHU Huiyuan, ZHANG Xianfeng, LIU Quan, LIU Minghou
2013, 43(5): 393-401. doi: 10.3969/j.issn.0253-2778.2013.05.007
A flat loop heat pipe (FLHP) with a mixed sintered wick was designed for cooling off high concentration photovoltaic (HCPV) solar cells. The effect of heat load, inclination angle and condenser parameters on the start-up and operating performance of the heat pipe was experimentally studied. It was found that the heat pipe can basically meet the needs of HCPV cooling both in heat load and installation angle requirements. The maximum heat load is up to 320 W (40 W/cm2) when the temperature of the heating surface is under 100 ℃. Relative positions between evaporator and accumulator, evaporator and condenser have important influences on the start-up and operating performance of the heat pipe. The pipe may start more easily when the compensation chamber is under the evaporator. The start-up temperature of low heat load drops when the condenser is placed above the evaporator. The capability of anti-gravity start-up performance of the heat pipe can be improved by reducing the flow rate of cooling water in the condenser.
A model for predicting smoke filling time in a compartment with ceiling vents based on the assumption of an irregular ceiling
LI Qiang, LU Shouxiang, ZHANG Jiaqing, CHEN Bing, LI Changhai
2013, 43(5): 402-409. doi: 10.3969/j.issn.0253-2778.2013.05.008
Based on the assumption of an irregular ceiling, a model was established for predicting smoke filling time in a compartment with ceiling vents. 24 experiments were conducted in a compartment with an interior dimension of 3.0 m(L)×3.0 m(W)×1.95 m(H). Four pool fires with diameters of 0.10, 0.14, 0.20 and 0.30 m, six ceiling vents with areas of 0.01, 0.04, 0.09, 0.14, 0.25, and 0.32 m2 were used in the experiments. Two methods for measuring smoke filling time with temperature and light extinction were used. A comparison of the model prediction results with those of the experiments shows a good agreement between them.
Relationship between credit risk and market value of listed companies based on copula method
HU Xinhan, YE Wuyi, MIAO Baiqi
2013, 43(5): 410-419. doi: 10.3969/j.issn.0253-2778.2013.05.009
Based on a variable selection method, the default probability of listed companies was calculated with a logistic model. Then kernel estimation and copula method were applied to fit the marginal and joint distribution between credit risk and changes in market value of listed companies. With conditional VaR, the applicability of the structure credit risk model was tested with large samples. Empirical tests show that there is a negative relationship between credit risk and market value which is affected by financial ratios and the default probability is sensitive to the decrease in market value. Besides, the main factor in forecast accuracy is the distribution of default probability, while the impact of the dependence structure between default probability and market value is not significant.
Deriving intuitionistic fuzzy number priority weights from intuitionistic judgment matrix
TU Zhenkun, LIU Xinbao
2013, 43(5): 420-428. doi: 10.3969/j.issn.0253-2778.2013.05.010
The problem of the weights of intuitionistic judgment matrix (IGM) was discussed, and the consistency of IGM, which is related to the reliability of the weights, was explored. From the perspectives of the score function and accuracy function of intuitionistic fuzzy value, a new definition of additive consistency of IGM was given, and an equivalent condition for additive consistency was achieved. To make full use of the information of the original IGM and make the decision meet the consistency, the original IGM was converted into two additive consistency fuzzy judgment matrices, which was achieved by the transformation function arising from the equivalent condition. The membership degree and the non-membership degree of the original IGMs weights were respectively achieved by normalizing rank aggregation to the two additive consistency fuzzy judgment matrices. Thus the intuitionistic fuzzy number priority weights of the IGM were obtained, and ranked with a sequencing rule for intuitionistic fuzzy values. The excellent properties of the proposed method were discussed, and its validity and practicability were illustrated in an example.