Conservation strategies for endemic fish species threatened by the Three Gorges Dam

The largest damming project to date, the Three Gorges Dam has been built along the Yangtze River (China), the most species-rich river in the Palearctic region. Among 162 species of fish inhabiting the main channel of the upper Yangtze, 44 are endemic and are therefore under serious threat of global extinction from the dam. Accordingly, it is urgently necessary to develop strategies to minimize the impacts of the drastic environmental changes associated with the dam. We sought to identify potential reserves for the endemic species among the 17 tributaries in the upper Yangtze, based on presence/absence data for the 44 endemic species. Potential reserves for the endemic species were identified by characterizing the distribution patterns of endemic species with an adaptive learning algorithm called a "self-organizing map" (SOM). Using this method, we also predicted occurrence probabilities of species in potential reserves based on the distribution patterns of communities. Considering both SOM model results and actual knowledge of the biology of the considered species, our results suggested that 24 species may survive in the tributaries, 14 have an uncertain future, and 6 have a high probability of becoming extinct after dam filling.

Performance improvement of GaN based Schottky barrier ultraviolet photodetector by adding a thin AlGaN window layer

We propose a new structure of GaN based Schottky barrier ultraviolet photodetector, in which a thin n-type AlGaN window layer is added on the conventional n(-)-GaN/n(+)-GaN device structure. The performance of the Schottky barrier ultraviolet photodetector is found to be improved by the new structure. The simulation result shows that the new structure can reduce the negative effect of surface states on the performance of Schottky barrier GaN photodetectors, improving the quantum efficiency and decreasing the dark current. The investigations suggest that the new photodetector can exhibit a better responsivity by choosing a suitably high carrier concentration and thin thickness for the AlGaN window layer.

LD side-pumped high beam quality passive Q-switched and mode-locked Nd:YAG laser based on SESAM

We report a LD side-pumped fundamental-mode (Mx(2) = 1.35 and My(2) = 1.27) passive Q-switched and mode-locked Nd:YAG laser based on a semiconductor saturable absorber mirror (SESAM). At a pump current of 12.5 A, the average output power of 5.68 W with 80 kHz repetition rate and 2 mu s pulse width of the Q-switched envelope was generated. The repetition rate of the mode-locked pulse within the Q-switched envelope of 88 MHz was achieved.

智能玻璃建筑节能特性分析

智能玻璃能够根据人的意愿或者外界环境的变化动态的调节太阳光的输入，是新一代的建筑节能玻璃，目前引起广泛的关注。本文选取了两种典型的智能玻璃——电致变色玻璃和VO2热色玻璃，采用动态能耗分析软件EnergyPlus分别对其建筑节能特性进行了分析，具体研究内容如下： （1）讨论了电致变色玻璃不同控制方式对其节能效果的影响。结果表明，电致变色玻璃选用合适的控制方式可以显著降低建筑的能耗，但如果控制方式选用不当，采用电致变色玻璃后建筑的能耗反而会高于采用普通白玻的能耗。此外，无论在何种控制方式下，采用电致变色/LOW-E的节能效果都要优于电致变色/白玻中空玻璃。 （2）对VO2光学薄膜的膜系结构进行了优化，研究了外观颜色与膜层厚度的关系，设计出的TiO2(135nm)/VO2(50nm)/ITO(45nm)/glass三层膜结构相对于VO2(50nm)/glass的单层膜结构，太阳能调节量提高了从3.7%提高到9.8%，半导体状态时的可见光透过率从33.6%提高到55.5%，金属状态时的可见光透过率从34.0%提高到50.0%，同时半导体与金属状态时的膜面发射率都有很大程度的降低。 （3）研究了VO2热色玻璃的热学性能和建筑节能特性，重点分析了膜层结构、膜面位置、建筑的地理位置等因素对VO2热色玻璃建筑节能效果的影响。结果表明，对于单层VO2热色玻璃，其功能膜面朝向室内比朝向室外可以获得更好的节能效果，而对于由VO2热色玻璃与白玻组成的双层玻璃，其功能膜面位于室内玻璃的外侧时VO2很难起到相应的调节作用。另外，与其他类型的玻璃相比，虽然一定膜层结构下VO2热色玻璃在不同地区的建筑能耗低于白玻，但是在全年以采暖为主的严寒地区和全年以空调为主的夏热冬暖地区，VO2热色玻璃的节能效果分别不及高透型和遮阳型LOW-E玻璃。

深地震探测的分辨率分析——以南海北部OBS数据为例

多次深地震探测结果表明南海北部陆缘地壳结构在走向和倾向上都有明显的变化.在一些相隔很近的测线上，

Broadly Tunable Grating-Coupled External Cavity Laser With Quantum-Dot Active Region

A broadly tunable and high-power grating-coupled external cavity laser with a tuning range of more than 200 nm and a similar to 200-mW maximum output power was realized, by utilizing a gain device with the chirped multiple quantum-dot (QD) active layers and bent waveguide structure. The chirped QD active medium, which consists of QD layers with InGaAs strain-reducing layers different in thickness, is beneficial to the broadening of the material gain spectrum. The bent waveguide structure and facet antireflection coating are both effective for the suppression of inner-cavity lasing under large injection current.

A study of the influence of initial liquid volume on the capillary flow in an interior corner under microgravity

In this work the influence of initial liquid volume on the capillary flow in an interior corner is studied systematically by microgravity experiments using the drop tower, under three different conditions: the Concus-Finn condition is satisfied,close to and dissatisfied. The capillary flow is studied by discussing the movement of tip of the meniscus in the corner. Experimental results show that with the increase of initial liquid volume the tip location increases for a given microgravity time, the achievable maximum tip velocity increases and the flow reaches its maximum tip velocity earlier However, the results for the three different conditions show some difference. (C) 2010 Elsevier Ltd All rights reserved

Fiber Bragg Grating Sensor for Strain Sensing in Low Temperature Superconducting Magnet

Fiber Bragg grating (FBG) sensor for monitoring the electromagnetic strain in a low temperature superconducting (LTS) magnet was studied. Before used to LTS magnet strain sensing, the strain response of the sensor with 1.54-mu m wavelength at liquid helium was experimentally studied. It was found that the wavelength shift showed good linearity with longitudinal applied loads and the strain sensitivity is constant at 4.2 K. And then, the hoop strain measurement of a LTS magnet was carried out on the basis of measured results. Furthermore, the finite element method (FEM) was used to simulate the magnet strain. The difference between the experimental and numerical analysis results is very small.

Fiber Bragg Grating Sensor for Strain Sensing in Low Temperature Superconducting Magnet

Fiber Bragg grating (FBG) sensor for monitoring the electromagnetic strain in a low temperature superconducting (LTS) magnet was studied. Before used to LTS magnet strain sensing, the strain response of the sensor with 1.54-mu m wavelength at liquid helium was experimentally studied. It was found that the wavelength shift showed good linearity with longitudinal applied loads and the strain sensitivity is constant at 4.2 K. And then, the hoop strain measurement of a LTS magnet was carried out on the basis of measured results. Furthermore, the finite element method (FEM) was used to simulate the magnet strain. The difference between the experimental and numerical analysis results is very small.