HF SAR image cross-correlation technique for high accuracy orbit positioning

A novel technique to determine the position of spacecraft orbits is proposed. The technique is based on the cross-correlation function of HF SAR images and is able to determine the relative position of orbits with an accuracy of ～ /4 or better, where is the wavelength of the HF radar pulse at its center frequency. The performance of the proposed technique was confirmed by simulation which was carried out under the condition of design facts of the SELENE LRS mission. The highly accurate orbit positioning ena...     

On Large-Time Behavior of Solutions to the Compressible Navier-Stokes Equations in the Half Space in R 3

 The Navier-Stokes equation for compressible viscous fluid is considered on the half space in R ³ under the zero-Dirichlet boundary condition for the momentum with initial data near an arbitrarily given equilibrium of positive constant density and zero momentum. Time decay properties in L ² norms for solutions of the linearized problem are investigated to obtain the rate of convergence in L ² norms of solutions to the equilibrium when initial data are sufficiently close to the equilibrium in . Some lower bounds are derived for solutions to the linearized problem, one of which indicates a nonlinear phenomenon not appearing in the case of the Cauchy problem on the whole space. (Accepted May 8, 2002) Published online October 18, 2002 Communicated by T.-P. LIU     

Advanced time-resolved absorption spectroscopy with an ultrashort visible/near IR laser and a multi-channel lock-in detector

Ultrashort visible-near infrared (NIR) pulse generation and its applications to ultrafast spectroscopy are discussed. Femtosecond pulses of around 800 nm from a Ti:sapphire laser are used as a pump of an optical parametric amplifier (OPA) in a non-collinear configuration to generate ultrashort visible (500–780 nm) pulses and deep-ultraviolet (DUV, 259–282 nm) pulses. The visible-NIR pulses and DUV pulses were compressed to 3.9 fs and 10.4 fs, respectively, and used to elucidate various ultrafast dynamics in condensed matter with a sub-10 fs resolution by pump-probe measurements. We have also developed a 128-channel lock-in amplifier. The combined system of the world-shortest visible pulse from the OPA and the lock-in amplifier with the world-largest channel-number can clarify the sub-10 fs-dynamics in condensed matter. This system clarified structural changes in an excited state, reaction intermediate, and a transition state. This is possible even during molecular vibration and reactions via a real-time-resolved vibronic spectrum, which provides molecular structural change information. Also, ultrafast dynamics in exotic materials like carbon nanotubes, topological insulators, and novel solar battery systems have been clarified. Furthermore, the carrier-envelope phase in the ultrashort pulse has been controlled and measured.     

一种新型的平面共轭的酞菁卟啉二联体的合成及光谱研究(英文)

5,10,15,20-四(4-氯苯基)-2′,3′-二氰基[2,3-β]卟啉和4,5-二(丁烷氧基)邻二氰基苯在锂存在的条件下在正戊醇中回流四聚,然后用醋酸处理得到了一种新型的平面共轭酞菁二联体H4{[(DAPc(OC4H9)6][TClPP]}(1)(其中DAPc(OC4H9)6是2,3,9,10,16,17-六(丁烷氧基)-22,25-二氮杂酞菁的二价阴离子,TClPP是5,10,15,20-四(4-氯苯基)卟啉的二价阴离子)。这种二联体和Zn(OAc)2.2H2O在DMF和甲苯混合溶剂中反应得到双金属配合物Zn2{[(DAPc(OC4H9)6][(TClPP)]}(2)。质谱和核磁共振光谱等一系列的表征方法证明了这种双核的混杂四吡咯结构。电子吸收光谱和磁圆二色谱证明了酞菁发色团和卟啉发色团之间存在有效的分子内电子相互作用。这一结论进一步得到了理论计算的支持。     

纤维素催化转化为高附加值化学品的研究进展

Currently,under huge pressure from energy demands and environmental problems,much attention is being paid to biomass conversion,which will play an important role in meeting the requirements for a sustainable society.As the most abundant biomass on earth, cellulose is usually used as the first research target for biomass conversion.In this review,the recalcitrant structure of cellulose is discussed and non-catalytic hydrolysis by hot-compressed water and catalytic hydrolysis using solid acids are then considered.We also review the catalytic conversion of cellulose into valuable chemicals including hexitols(sorbitol and mannitol),ethylene glycol,and related compounds using various heterogeneous catalysts.     

煤粉加压气流床气化特性实验研究

煤气化技术由于具有高煤炭利用率和低污染排放,近年米得到快速发展.我国煤种灰熔点普遍偏高,约占保有储量的57%,无法满足现有液态排渣气流床气化技术的需要.为扩大该技术对我国高灰熔点煤种的适应性,本文在25kg/h规模的加压气流床气化装置上,对我国高灰熔点煤种进行了气化特性实验研究.研究结果表明:高温有利干气化反应向吸热方向进行,碳转化率升高,但过多氧气存在,使得气化炉内燃烧份额增加,导致合成气中 CO2和H2O的含量升高,CO、H2含量降低,冷煤气效率下降,因此,存在最佳气化温度.本实验条件下,最伟气化温度为1300～1350℃;1350℃连续运行1小时30分,此时气化炉底部和旋风分离器内的灰渣,整体上仍以固态形式存在,只有灰中部分低熔融成分发生熔融,其熔融部分在数μm左右.     

ChemInform Abstract: Si60 Clusters: AM1 Computed Ih/C2v Relative Populations

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