Table of Content

20 May 2003, Volume 39 Issue 3

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Energetic Particle Event Observed by a Polar Orbit Satellite at 780km

ZOU Hong,XIAO Zuo,WU Zhongxiang,ZHU Wenming

2003, 39(3):  370-374. 

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The first set of data collected by the energetic particle detectors on board of the ZY-1, a China Brasilia coordinated earth resource satellite, were introduced briefly in this paper. ZY-1 is a polar orbiting satellite at an altitude of 780km and launched on 14th October 1999. This is the first time that such measurement is carried out inside a satellite cabin. For the purpose of statistics, a consecutive set (around at least 3 to 5 times) of distinguishable records of electrons or protons was defined as a particle event. The preliminary analysis shows that almost all of the events recorded are located at polar and South Atlantic regions (SAA). In the northern polar region, at the same longitudes of SAA, there is a clear gap of occurrence of flux events. Proton events in general only occur in SAA region while electron events appear at both SAA and polar regions.Electron flux of 0.5～2.0MeV in polar regions is dominant over that of 2～15MeV，while at SAA, fluxes from the two channels are about the same. There is a close correlation between energetic particle radiation inside and outside the satellite.

A Test for the Ability of Mesoscale Numerical Model Using the Data of the Hong Kong Wind Profiler

LIU Shuyuan,TAO Zuyu,SUN Jian

2003, 39(3):  375-380. 

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Comparisons were made between the characteristics of the wind profile observed by the wind profiler and the wind profile simulated by mesoscale numerical model(MM5)from 8th June 1998 to 9th June 1998 at Hong Kong. The results showed that the wind profile simulated by MM5 is similar to that observed by the wind profiler. This confirmed the rationality of researching the structure and mechanism of the mesoscale convective system using MM5.

The Action of Rare Earth Elements in Ag-BaO Thin Films

XU Beixue,YANG Hai,LIU Weimin,XUE Zengquan,WU Jinlei

2003, 39(3):  381-385. 

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The action of rare earth elements doped in Ag-BaO thin films is discussed, based on the colloidal particles theory and experimental results. It shows that, influenced by the size and shape of Ag nanoparticles, increasing optical absorption and improving transport condition are two ways to enhance the photoemissive current density. With the action of rare earth elements, the Ag particles become smaller and spheroid. As a result, the total surface square of Ag particles increases, the optical absorption increases, the equivalent barrier between a metallic particle and the host semiconductor decreases, and the transport condition improves. So, the rare earth elements can enhance the photoemission of Ag-BaO thin film.

Synthesis and Field Emission Study of Large-Scaled Aligned Carbon Nanotube Films

GE Song,FENG Sunqi,YU Dapeng,ZHANG Guangyu,LIU Shuang

2003, 39(3):  341-346. 

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Large-scaled highly oriented carbon nanotube films on Si substrate with Ni as a catalyst were synthesized by hot-filament-enhanced CVD and field-emission properties of the films were studied. It has been discovered that there is a knee-point E_s on Fowler-Nordheim curves of the nanotube films, the slope of F-N curve in the low field region is much higher than that in the high field region. The field-enhancement factor β is proportional to the distance d between the anode and the cathode, and E_s is an inverse measure of the distance d. Both of them can be phenomenally interpreted by the two-region field-emission model. The possible mechanisms for the saturation of emitter current on high field region have been discussed.

Climatic Variability of Monthly Average Global and Hemispheric Air Temperature in Recent 150 Years

CAI Song,LI Xiaodong

2003, 39(3):  347-355. 

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The characteristics of variability of monthly average global and hemispheric air temperature in recent 150 years were analyzed. The correlations of the variability and the air temperature series were also discussed.

Spatial Correlation of Multi-Path Fading Channel and Its Effects on Spatial Diversity Receiver

CHEN Jiang,JIANG Wei,SHANG Yong,LIANG Qinglin

2003, 39(3):  386-393. 

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In cellular systems, the performance degradation caused by multi-path fading may be reduced by applying diversity antennas at base stations (BS) to recover the signals received on uplink. But the characteristics of the fading signals received on different antennas may be somehow correlative when the distance between antennas are constrained, thus the anticipated diversity gain may not always be obtainable. This paper proposes a modified multi-path uplink channel model based on the local scattering phenomena aroused around the mobile station. The effects of different channel model setups on the system performance are analyzed by purposeful simulations in the frame of the channel model proposed. Furthermore, this paper also proposes an effective numeric approach to calculate the BER performance in correlated Gaussian fading channel, given the correlation matrix of the channel.

Large Third-Order Optical Nonlinearity of SnO₂/PVA Composite Thin Film Measured by Femtosecond Optical Kerr Effect Method

LIANG Ruisheng,GONG Qihuang,WANG Shufeng,HUANG Wentao,WANG Dehuang,CHENG Humin,MA Jiming

2003, 39(3):  356-360. 

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The third-order nonlinear susceptibility χ⁽³⁾ of SnO₂/PVA composite thin film was measured by a femtosecond time-resolved optical Kerr effect OKE at 810nm wavelength. The χ⁽³⁾ observed was 4.301×10^-14esu for SnO₂ nanoparticles which average diameter is 10nm and 1.728×10^-13esu for 2～3nm SnO₂ nanoparticles. Femtosecond time-resolved OKE measurements revealed that the response time of the optical nonlinearity in SnO₂/PVA thin film is extremely fast as short as 50fs.

Energetic Particle Detector on Board “ZY-1” Satellite

XIAO Zuo,ZOU Jiqing,ZOU Hong,ZHONG Weiying,HUO Hongda,BAO Shanglian,XU Pingfang,ZHU Wenming,WU Zhongxiang

2003, 39(3):  361-369. 

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The preliminary results of data analysis of CBMC not only reveal the effects of polar particle precipitation and inner radiation belt on radiation environment inside a satellite, but also show some important features of the geo-space energetic particle radiation. A brief but overall description of the instrument was given and a few preliminary conclusions of data analysis were presented.

An Estimation of the Growth of Chinese Web Pages

LI Xiaoming

2003, 39(3):  394-398. 

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It is presented that a model for estimating number of previously existing web pages in terms of last-modify-time attribute of HTTP response header. In particular, this model has been used to estimate the growth of Chinese web pages since 1995. The result strongly supports the common sense that the Web is exponentially growing in terms of annual statistics.

New Algorithms Based on BPLI Solution for Reconstructing 3-D Surfaces from Parallel Contours

HE Jinguo,ZHA Hongbin

2003, 39(3):  399-411. 

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The correspondence and branching problems are vexed problems when reconstructing 3-D surfaces from 2-D parallel contours. BPLI tries to reconstruct non-intersecting surfaces from arbitrary input set of contours and latch a lambent solution of the two problems; however, BPLI remains the shortages of producing degenerate portions and involving time-consuming operations. After an overall analysis of BPLI, this paper proposed a series of new algorithms to improve BPLI approach: first, we proposed a new contour matching algorithm so that the correct similar contour portions of each pair of adjacent slices can be found though the contours are not finely segmented. Secondly, we triangulate the unmatched portions with a new dynamic programming scheme, which has ability to handle degenerate portions in the mesh. These improvements result in a fast triangulating process.

Structural and Electronic Properties of Hydrogen-Doped Endohedral Fullerene H@C₆₀and Exohedral Fullerene HC₆₀⁺

LU Jin,ZHOU Yunsong,ZHANG Shuang

2003, 39(3):  412-418. 

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Single hydrogen-doped endohedral fullerene H@C₆₀ and exohedral fullerene cation HC₆₀⁺ are investigated via semiempirical and first principles calculations. The most stable configuration of H@C₆₀ corresponds to the H atom on the center of the C₆₀ cage, a result consistent with the recent Bingel transformation experiments. The geometry of HC₆₀⁺ is quite similar to its neutral species. Its electronic structure is characterized by a strong localization of the LUMO on the dopant H site and a half-reduced HOMO-LUMO energy gap relative to that of C₆₀.The agreement between the calculated and observed electronic spectra of HC₆₀⁺ confirms its oxidation state in solution.

A Numerical Simulation Study of PM10 Pollution in Beijing during Summer Time

WANG Xuesong,LI Jinlong

2003, 39(3):  419-427. 

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A 3-D Eulerian regional air quality model, CAMx, is used to simulate the temporal variation and spatial distribution of PM10 in Beijing during summertime. The results show the prominent temporal and spatial variation characters of PM10. PM10 diurnal variation shows peaks around midnight and in the morning, an increasing trend around noon in urban areas because of the secondary aerosol production from photochemical reactions, a lowest concentration in early evening. The spatial distribution of PM10 has close relation to the source emission and is affected by the secondary aerosol production from photochemical reactions around noon. The secondary aerosol is an important portion of PM10. The secondary aerosol plays a main role on the concentration variation of sulfate and nitrate, while the concentration level and variation of organic carbon aerosol and PM10 is determined mainly by the primary aerosol.

Research on Reservoir Characteristics of Carboniferous Bioclast Limestone Member in Maigaiti Slope, Tarim Basin

JIANG Lingzhi ,YU Delong

2003, 39(3):  428-434. 

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By analyzing the photos of scanning electron microscopy and thin section, intrusive mercury curve and materials of porosity and permeability, the reservoir characteristics of bioclast limestone member are discussed, which include petrologic feature, pore structure, reservoir space and reservoir properties of matter. Although the reservoir is deep buried, and primary pore was seriously destroyed by earlier compaction and cementation, the secondary pore developed very well by latter solution and dolomitization, especially dolomitization. Bioclast limestone member is quite capable of reserving oil and gas, and is classified as reservoir Ⅱ.

The Gravitational Equilibrium of Spherically Symmetric Stars and the Oscillation near the Equilibrium

XU Renxin,QIAO Guojun

2003, 39(3):  435-437. 

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The relation between the stellar oscillation frequency and the average density is obtained by a semi-qualitative consideration of the equilibrium between gravity and pressure. It is explained to measure a stellar distance according to a period-luminosity relation.

Flow-Shop Scheduling Problem Based Improved Adaptive Genetic Algorithms

CHI Bin,YE Qingkai,XING Fei

2003, 39(3):  294-300. 

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Two kinds of improved adaptive genetic algorithms and encoding & decoding methods are presented. The experiment data shows that the improved adaptive genetic algorithms are superior to the pure genetic algorithms and other adaptive genetic algorithms in qualify of solution and efficiency.

A Condition of Transforming General Dynamical Systems into Linear Birkhoffian Dynamical Systems

ZHANG Xingwu,HUANG Kefu,LIU Kaixin

2003, 39(3):  309-315. 

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A condition of transforming general linear dynamical systems into linear Birkhoffian dynamical systems is studied. The condition and the procedure of transformation is given and proved. A theorem of the equivalence between linear Birkhoffian systems and linear Hamiltonian systems is given. According to the condition given by using the Jordan form, the non-degenerate condition of the Birkhoff tensor is analyzed from several aspects.

Nucleation and Growth Mechanism of the GaN Nanowires

JIA Shengguo,YU Dapeng

2003, 39(3):  336-340. 

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GaN material is one of the most attractive semiconductor materials. It is reported that the latest research results in the nucleation and growth mechanism of the GaN nanowires, which is grown by CVD method. Emphasis was paid on the effect of growth temperature and catalyst. Through analysis of the morphologies, microstructures, and their dependence on the growth temperature and catalyst, a clear understanding on the growth of the GaN nanowires is figured out, which is the key for a controlled growth of high quality GaN nanowires and can be used for nanodevices.

Experimental Investigation on the Rebuilding Project of Peacock Art Square in Kunming Expo Garden

ZHANG Zhen,LI Yiming,SUN Zhili,YAN Dachun,SONG Xiaobing

2003, 39(3):  301-308. 

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The experimental investigation on the Rebuilding Project of Peacock Art Square in Kunming Expo Garden is presented in this paper. During the experiment, the local wind field is simulated, in the same time, the mean wind pressures and the RMS wind pressures on the roofs of audience area and platform, as well as the frequency of vortex sledding in the downstream of the audience area are measured. Experimental results show that, because of the influence of vortex sledding in the downstream of the cliff, the instantaneous wind pressures on the roofs are very high, the wind pressure distributions on the roofs of the audience area vary obviously in main wind direction, and the RMS wind pressures are very strong. The mean wind pressures on the roofs of platform are small, but its instantaneous wind pressures are very high.

Study on Numerical Simulation of the Annular Jet Formation and Penetration

WANG Cheng,NING Jianguo,LU Jie

2003, 39(3):  316-321. 

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The coupling computation method which combines numerical solution and analytical one is used in simulating the annular jet formation and penetration into the target. The actual results indicate that this is the method is of having better computational precision and saving lots of computational time. It can be applied in the design of shaped charge.

An Adapter for Beam Loading Compensation of IH Linear Accelerators

LU Yuanrong,U Ratzinger,N Angert

2003, 39(3):  322-330. 

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The effective permeability of ferrite can be adjusted by different perpendicular biased magnetic intensity. Such characteristic could be used to manufacture variable characteristic impedance transmission line. The RF power feeder of IH linear accelerator has different input impedance with different accelerating beam current. An adapter based on above ferrite dominated transmission line has been designed and can compensate the beam loading effects and realize the impedance matching between RF high power amplifier and IH cavity automatically. The relevant computer code has been developed.

The Improvement of Extractive Emission in InGaAlP Quantum Wells Light Emitting Diodes by Microstructures

SUI Wenhui,ZHANG Bei,WANG Dajun,LUAN Feng,XU Wanjin,MA Xiaoyu

2003, 39(3):  331-335. 

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To solve the problem of low extractive efficiency in semiconductor light emitting diodes(LED), a proposal of introducing microstructures onto the top of LED was presented. Based on this idea, the InGaAlP quantum wells LEDs with centric ring-grooves microstructures have been successfully prepared by the conventional micro-fabrication. As a result, the vertical extractive light intensity from the novel LED was obviously stronger than that of the LED without microstructures. This success provides a new method for improving extraction efficiency from LED.