Neural network retrieval of ocean surface parameters from SSM/I data

A new algorithm based on the multiparameter neural network is proposed to retrieve wind speed (WS), sea surface temperature (SST), sea surface air temperature, and relative humidity ( RH) simultaneously over the global oceans from Special Sensor Microwave Imager (SSM/I) observations. The retrieved geophysical parameters are used to estimate the surface latent heat flux and sensible heat flux using a bulk method over the global oceans. The neural network is trained and validated with the matchups of SSM/I overpasses and National Data Buoy Center buoys under both clear and cloudy weather conditions. In addition, the data acquired by the 85.5-GHz channels of SSM/I are used as the input variables of the neural network to improve its performance. The root-mean-square (rms) errors between the estimated WS, SST, sea surface air temperature, and RH from SSM/I observations and the buoy measurements are 1.48 m s(-1), 1.54 degrees C, 1.47 degrees C, and 7.85, respectively. The rms errors between the estimated latent and sensible heat fluxes from SSM/I observations and the Xisha Island ( in the South China Sea) measurements are 3.21 and 30.54 W m(-2), whereas those between the SSM/ I estimates and the buoy data are 4.9 and 37.85 W m(-2), respectively. Both of these errors ( those for WS, SST, and sea surface air temperature, in particular) are smaller than those by previous retrieval algorithms of SSM/ I observations over the global oceans. Unlike previous methods, the present algorithm is capable of producing near-real-time estimates of surface latent and sensible heat fluxes for the global oceans from SSM/I data.

含尘大气近地层流底层流动特性及其摩阻系数

采用双向耦合的双流体模型，了大气悬浮沙尘的存在对大气边界层中流底层流动特性及摩阻系数的影响，计算并讨论了不同沙尘含量下含尘大气相对于无尘大气摩阻系数的变化，结果表明，摩阻系数的变化取决于悬浮沙尘的初始运动状态和质量载荷率。

Widely tunable quasi-phase-matched optical parametric amplification in infrared region using periodically poled lithium niobate

Widely tunable optical parametric amplification (OPA) in the IR region through quasi-phase-matching technology is demonstrated theoretically in periodically-poled lithium niobate (PPLN). For a 532nm pump wavelength and a broadband signal wavelength near 1300 nm, we can obtain the optimum grating period from phase-matching curves for different grating periods to achieve continuously tunable OPA by tuning the angle in a small range. Tunable OPA range of 200nm near 1300 mn can be obtained with a tuning incidence signal angle of 2.2 degrees.

图像处理在光路自动准直系统中的应用

光路自动准直系统应用于惯性约束聚变的高功率激光装置中的光束自动调整。图像处理是光路自动准直的关键技术之一。针对神光Ⅲ原型装置，结合阈值化、重心法、中值滤波和圆拟合等多种不同的图像处理方法设计了一套合理的准直方案，并且在模拟实验平台上进行了实验验证。实验结果表明，光路自动准直系统能够在15min之内顺利完成光路的自动调整，光束近场调整精度优于近场光斑的±0．5％，光束远场调整精度≤±0．3″，满足了原型装置的总体要求。

静动结合的化学腐蚀法制备近场光学探针的理论分析

理论上分析了静动结合的化学腐蚀法制备探针的具体机理及过程。在静态腐蚀的过程中, 利用流体力学Young-Laplace方程的一级近似解获得了光纤插入到HF酸中形成的新月形高度。在动态腐蚀过程中, 详细分析了当静态腐蚀时间和动态腐蚀时间分别取不同值时, 光纤移动速度对光纤探针结构的影响。利用此法可制备出尖端锐利、大锥角或多锥体等各种结构的光纤探针。这为实验上制备出性能优良的探针, 为拓宽扫描近场光学显微镜的应用范围奠定基础。将上述理论分析的结果与本文实验中所得初步结果进行了比较, 所得结果一致。

Infrared (1.2-1.6 mu m) luminescence in Yb, Cr : YAG with 940 nm diode pumping

Infrared (1.2-1.6 mum) luminescence in a yttrium aluminium garnet (YAG) crystal, co-doped with Yb (10 at.%) and Cr (0.05 at.%) ions, was investigated under CW laser diode pumping (lambda = 940 nm). The Cr4+ emission band was observed with its peak at 1.35 mum and measured to be about 6% with respect to Yb3+ IR luminescence (lambda = 1.03 mum). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+-Cr4+ energy transfer is a mechanism responsible for the B-3(2)(T-3(2))-B-3(1)((3)A(2)) emission of Cr4+ ions. This crystal is promising as an efficient source of the near infrared emission. (C) 2004 Elsevier B.V. All rights reserved.

Nonradiative recombination centers in Ga(As,N) and their annealing behavior studied by Raman spectroscopy

Nitrogen-related defects in diluted Ga(As,N) have been detected by Raman scattering in resonance with the localized E+ transition. These defects are attributed to local vibrational modes of nitrogen dimers on Ga- and As-lattice sites. Rapid thermal annealing under appropriate conditions is found to be able to remove the nitrogen dimers. The required minimum annealing temperature coincides with the threshold-like onset of strong, near-band-gap photoluminescence. This finding suggests that the nitrogen dimers are connected with nonradiative recombination centers. (C) 2004 American Institute of Physics.

Detect the sub-wavelength data by applying a very-small-aperture laser

We present a theoretical and experimental research about applying a very-small-aperture laser (VSAL) to detect sub-wavelength data. Near-field distribution of a VSAL, which is essential for the application of such near-field devices, will be affected by the sample or fiber posited in the near-field region of the aperture. When the device is applied to detect the sub-wavelength data, the real resolution depends on the near-field spot size, the divergent angle of the beam and the distance from the aperture to the sample. Experimental results, including the near-field detection of the spot and detection of the sub-wavelength data by using the VSAL, are presented in this paper. We realize the two dimensional scanning about the sub-wavelength data (with the width 600 nm) by employing a VSAL with a 300 nm x 300 nm aperture.

High-quality GaN grown by gas-source MBE

High-quality GaN epilayers were consistently obtained using a home-made gas-sourer MBE system on sapphire substrates. Room-temperature electron mobility of the grown GaN film is 300 cm(2)/V s with a background electron concentration as low as 2 x 10(17) cm(-3) The full-width at half-maximum of the GaN (0 0 0 2) double-crystal X-ray rocking curve is 6 arcmin. At low temperature (3.5 K), the FWHM of the: near-band-edge photoluminescence emission line is 10 meV. Furthermore, using piezoelectric effect alone with the high-quality films, two-dimensional electron gas was formed in a GaN/AlN/GaN/sapphire structure. Its room-temperature and low-temperature (77 K) electron mobility is 680 cm(2)/V s and 1700 cm(2)/V s, and the corresponding sheet electron density is 3.2 x 10(13) and 2.6 x 10(13) cm(-2), respectively. (C) 2001 Published by Elsevier Science.

High-quality GaN grown by gas-source MBE

High-quality GaN epilayers were consistently obtained using a home-made gas-sourer MBE system on sapphire substrates. Room-temperature electron mobility of the grown GaN film is 300 cm(2)/V s with a background electron concentration as low as 2 x 10(17) cm(-3) The full-width at half-maximum of the GaN (0 0 0 2) double-crystal X-ray rocking curve is 6 arcmin. At low temperature (3.5 K), the FWHM of the: near-band-edge photoluminescence emission line is 10 meV. Furthermore, using piezoelectric effect alone with the high-quality films, two-dimensional electron gas was formed in a GaN/AlN/GaN/sapphire structure. Its room-temperature and low-temperature (77 K) electron mobility is 680 cm(2)/V s and 1700 cm(2)/V s, and the corresponding sheet electron density is 3.2 x 10(13) and 2.6 x 10(13) cm(-2), respectively. (C) 2001 Published by Elsevier Science.

单向流作用下近壁面圆柱的流向振动

在单向流水槽中对近壁面圆柱体的流向振动进行了实验模拟.分析了圆柱流向振动位移时程曲线,探讨了圆柱振动频率随水流速度的变化特征.研究了圆柱振动幅值和频率的变化特性,结合圆柱尾迹涡的变化规律,分析了流向振动的起因.实验结果表明:随着流速的增加,圆柱流向振动经历了发生、发展和消失的变化过程,振动频率呈现出缓慢增长的趋势;在流向振动触发初期和后期衰退时,流向振动频率存在多值现象,频谱中呈现多个谱峰:圆柱流向振动所对应的约减速度范围明显小于横向涡激振动所对应的范围.

基于ANSYS的近底床悬跨海管建模技术研究

以ANSYS软件为平台建立了近底床钢管-混凝土单层悬跨海管有限元模型.该模型综合应用PIPE59,MATRIX27和COMBIN40三个单元不仅模拟了海流对管道的作用,而且还模拟了管内流体流动引起的科氏力和离心力,另外还考虑了海管与底床的弹性接触.通过与CAM和DNV工程规范对比,验证了该模型.研究结果表明,所提出的建模方法可方便地应用于含内流的近底床悬跨海管的计算

角蟾科（Megophryidae; Anura）蝌蚪的形态多样性和生态适应

角蟾科（Megophryidae）是以角蟾属（Megophrys Kuhl and Van Hasselt, 1822）为模式属而建立的，隶于无尾目（Anura），变凹型亚目（Anomocoela）。角蟾科包括2 亚科11 属142 种，分布于东洋界，从巴基斯坦、中国西部向东直到菲律宾和苏达群岛；中国有9 属75 种分布于华中和华南地区。角蟾科被认为是原始的两栖动物之一，其分类学、系统学、生态学、动物地理学的研究均深受中外科学家的瞩目。近年来，通过形态学、古生物学、细胞学、生态学、支序系统学的研究，角蟾科的分类与系统学研究取得了较大进展。与成体形态和分子系统学研究结果相比较，蝌蚪的研究存在更多的问题和挑战，尚需深入研究：（1）角蟾科蝌蚪的形态多样性分析；（2）角蟾科的系统发育关系与蝌蚪的演化，以及口漏斗的起源；（3）角蟾科蝌蚪表型分化与栖息环境和觅食行为的适应演化。针对上述问题，本文对角蟾科9 属30 种蝌蚪的形态特征，包括外部宏观形态和口器外部结构特征、口器内部显微结构、唇齿和角质颌的亚显微结构作了深入细致、多层次的比较研究；通过12s rRNA 和cytochrome b 基因构建最大简约树，采用贝叶斯系统发育进行分析，蝌蚪型的演化采用祖先性状的重建方法分析；得到如下结论：1）初步将角蟾科蝌蚪分为4 种类型；并且建立了2 种新的角蟾科蝌蚪类型。A 型：拟髭蟾型蝌蚪，该型蝌蚪包括拟髭蟾属、髭蟾属、齿蟾属和齿突蟾属的物种；B 型：新类型，掌突蟾型蝌蚪，该型蝌蚪在本文中包括掌突蟾属、小臂蟾属的物种；C 型：新类型，短腿蟾型蝌蚪，一种特化类型，该型蝌蚪在本文中仅包括短腿蟾属的物种；D 型：角蟾型蝌蚪，该型蝌蚪在本文中包括无耳蟾属、小口拟角蟾属和异角蟾属的物种。2）对角蟾科的分类进行了修订：（1）支持角蟾科两个亚科的分类系统；（2）角蟾亚科包括拟角蟾属、异角蟾属、无耳蟾属和短腿蟾属；该亚科形态差异小，系统学关系比较复杂，暂不作族级分类的再划分；（3）拟髭蟾亚科分为2 个族：拟髭蟾族，该族物种具有类型A 的蝌蚪，包括4 个属：拟髭蟾属、髭蟾属、齿蟾属、齿突蟾属；掌突蟾族，该族物种具有类型B 的蝌蚪，包括2 个属：掌突蟾属和小臂蟾属。3）结合分子系统进化关系探讨了4 种蝌蚪类型的演化。（1）角蟾科蝌蚪的最近共同祖先来自于一类具有拟髭蟾型蝌蚪性状的蝌蚪；（2）掌突蟾型蝌蚪和角蟾亚科的蝌蚪是由具有拟髭蟾型蝌蚪性状的祖先蝌蚪分别演化而来；（3）短腿蟾型蝌蚪是角蟾型蝌蚪的一种特化类型；（4）外群蝌蚪具有与拟髭蟾型蝌蚪相似的性状，进一步印证了类拟髭蟾型蝌蚪是角蟾科蝌蚪的最近共同祖先的假说；（5）具有口漏斗的蝌蚪类型是由不具口漏斗的蝌蚪类型演化而来，在角蟾科中口漏斗是一种衍生性状。4）分析了角蟾科四种蝌蚪类型与栖息环境的适应演化。（1）角蟾科蝌蚪的口部和体形的变化反映了该科蝌蚪由缓流向类似静水生境的回水凼的渐变式适应，角蟾科蝌蚪的形态显示了多方面的适应变化；（2）随着蝌蚪类型由A 向D的演化，当水速较大时，拟髭蟾型的蝌蚪营流水攀吸型生活方式；当水速递减时，掌突蟾型蝌蚪营流水附着型生活方式；当水速进一步递减时，具有较小口漏斗的短腿蟾型蝌蚪和具有大漏斗的角蟾型蝌蚪营流水浮泳型生活。角蟾科蝌蚪对于水流递减的适应演化说明蝌蚪的生态学适应是具有进化意义的；（3）蝌蚪口器内部结构的分化揭示了蝌蚪和食性的适应关系，蝌蚪以口部的唇齿与角质颌刮取或吞吸水中的物质，然后，通过口乳突有选择地过滤进入口腔中食物。拟髭蟾亚科蝌蚪的唇齿多而窄，唇齿间距宽，颌鞘粗而稀，反映了其植食性为主的特点；它们的舌前乳突一般为指状，在口腔入口处所占面积小，其机械过滤的作用很多被唇齿和角质颌分担了；而角蟾亚科的蝌蚪，其角质颌弱，其舌前乳突一般为匙状，几乎填满了口腔入口处，因此舌前乳突起了主要的机械过滤作用。The family Megophryidae is the largest and most diverse families inArchaeobatrachia, and most of its species occur in India, Pakistan, and eastward intoChina, Southeast Asia, Borneo and the Philippines to the Sunda Islands. Currently thefamily includes 142 species have been grouped into two subfamilies, Megophryinaeand Leptobrachiinae. The mountains of central and southern China are rich in speciesof Megophryidae, 75 species belong to 9 genera and two subfamilies.The family was supposed to be ideal materials of studies in many fields of biology,such as taxonomy, evolution, systematics, ecology, and biogeography. Recently, therehave a great development in taxonomy and systematics of megophryids throughstudied by morphology, paleontology, cytology, ecology, and cladistics. However,larvae of megophryids were generally unknown, although the tadpoles might be veryimportant for above studies.In this paper, we examined the evolutionary scenario of the tadpoles’ morphologyin the context of a phylogenetic framework. Our objectives are (1) to evaluate thedivergence of larval body shape and oral discs in the family Megophryidae, (2) toexplore the evolutionary trends of the larvae in megophryidae, and test if thefunnel-shaped oral disc is apomorphic, and (3) to explore the relationship of the larvalstructure, diet and microhabitat.We examined larval morphology of 30 megophryid species, the larval body shape,oral discs, the buccopharyngeal cavity, and jaw sheaths and denticles of the Chinesemegophryid frogs were re-examined. We constructed a phylogeny of the species on thebasis of published mitochondrial cytochrome b and 16S rRNA gene segments usingpartitioned Bayesian analyses. Furthermore, hypothetical changes of larval morphologywere inferred using parsimony principle on the phylogeny. The results showed that:1) Four tadpole types in Megophryidae. The larval morphological charactersseries in Chinese megophryids fall into four general categories according to the bodyshape and oral discs: (A) Leptobrachiini type, species from genera Leptobrachium,Oreolalax, Scutiger and, Vibrissaphora share this type of tadpoles. (B) Leptolalax type,species of genus Leptolalax have this type of tadpoles. (C) Brachytarsophrys type,species of the genus Brachytarsophrys have this type of tadpoles. (D) Megophryinitype, species of the genera Atympanophrys, Ophryophryne, and Xenophrys share this type of tadpoles. Of which B and C are two novel types.2）Taxonomic implications. The present study leads us to reconsider the generalclassification of tribes attributed to members of Megophryidae. More specifically,concerning the phylogenetic relationships and the two novel tadpole types describedherein, we propose a provisional taxonomy for the family but suggest that further taxasampling of other megophryids be performed to confirm this taxonomic change. TheMegophryidae is composed of two subfamilies (Leptobrachiinae and Megophryinae).The Leptobrachiinae was recogonized the two tribes: (1) tribe Leptobrachiini sensuDubois, corresponding to the tadpole of type A, including four genera, i.e.,Leptobrachium, Oreolalax, Scutiger and, Vibrissaphora; (2) tribe Leptolalaxini,corresponding to the tadpole of novel type B, including two genera, i.e., Leptolalaxand Leptobrachella. However, the relationships among the genera of Megophryinaewere largely unresolved, they recognized no monophyletic groups above the generalevel. A more thorough sampling will likely foster a better taxonomic solution.3) The larval evolutionary scenario in Megophryidae.Type A is characteristicof normal-mouthed with multiple tooth rows, representing the tadpole type of theMRCA of Chinese megophryids. Type B is characteristic of normal-mouthed withreduced tooth rows, prolonging labium, and integumetary glands. Type C ischaracteristic of no labial teeth and smaller umbeliform oral disc. Type D ischaracteristic of no labial teeth, enlarged umbeliform oral disc, representing the tadpoleof the MRCA of subfamily Megophryinae. A previous hypothesis, referring tofunnel-shaped oral discs as an apomorphy, is supported.4) The larval adaptation to habitats in Megophryidae. Tadpoles generallyadhere to substrates using their mouths, and the microhabitat that the tadpoles occupyreflects the degree of adhesion and oral complexity. The morphological changes inmegophryid tadpoles virtually allow a progressive adaptation to a changing habitatfrom faster water to slower water. Within the tadpoles of Type A to type D, the TOTbecomes smaller and smaller, and the oral disc orientates from anteroventral toumbelliform upturned, and eye position orientates from dorsal to lateral, and the trunkis more and more depressed and tail becomes relatively longer and slender. Within therunning water, the normal-mouthed with multiple tooth rows of Leptobrachiini tadpoles are correlated with lotic-suctorial, benthic feeders with anteroventral oraldisc and the largest body. With the water’s velocity decreasing, the lotic-adherentfeeders of Leptolalax tadpoles have tube-shaped labium with reduced tooth rows andintegumetary glands. And then, the smaller umbeliform in Brachytarsophrys tadpolesand the enlarged umbeliform oral disc in the Megophryini tadpoles are inhabitmicrohabitats of non-flowing backwaters of rivers, indicative of adaptive traits oflotic-neustonic surface feeders. The scheme of megophryid tadpoles andmicrohabitats provided the first clear evidence which congruent with the hypothesis ofAltig and Johnston (1989). The ecological divergence plays a general role in thedivergence and evolution of megophrid larvae. There is a definite correlation amongthe buccopharyngeal cavity, diet and feeding mechanisms, the tadpole graze orswallow the food particles, then through papillae which like a sieve and sort out foodparticles to the oesophagus. The tadpole of Leptobrachiinae possess multiple toothrows, wide intertooth distance as well as thick and sparse jaw sheath, these tadpolesinhabit bottom of the streams and graze on epiphyton or major detritus of organicmatter on the substrates, their prelingual papillae like single finger, the mechanicalpurpose of papillae served share in by tooth and jaw. The tadpoles of Megophryinaeoccur near the water surface of small streams and are the filter feeder, their dietincludes plankton and organic debris floating on the water surface, those tadpolepossess weak jaw, their prelingual papillae like spoon, the mechanical purpose ofpapillae served mostly for sieve.

Photon production in a chemically equilibrating quark-gluon plasma at finite Baryon density: Complete leading order results

We investigate hard photon production of the near-collinear bremsstrahlung and a new process called the inelastic pair annihilation, fully including the LPM effect, in a chemically equilibrating quark-gluon plasma at finite baryon density, and find that the effect of the system evolution on the photon production and large contribution of the bremsstrahlung make the total photon yield of the two processes as a strongly increasing function of the initial quark chemical potential.

Azimuthal di-hadron correlations in d plus Au and Au plus Au collisions at root s(NN)=200 GeV measured at the STAR detector

Yields, correlation shapes, and mean transverse momenta p(T) of charged particles associated with intermediate-to high-p(T) trigger particles (2.5 < p(T) < 10 GeV/c) in d + Au and Au + Au collisions at root s(NN) = 200 GeV are presented. For associated particles at higher p(T) greater than or similar to 2.5 GeV/c, narrow correlation peaks are seen in d + Au and Au + Au, indicating that the main production mechanism is jet fragmentation. At lower associated particle pT < 2 GeV/c, a large enhancement of the near- (Delta phi similar to 0) and away-side (Delta phi similar to pi) associated yields is found, together with a strong broadening of the away-side azimuthal distributions in Au + Au collisions compared to d + Au measurements, suggesting that other particle production mechanisms play a role. This is further supported by the observed significant softening of the away-side associated particle yield distribution at Delta phi similar to pi in central Au + Au collisions.