Experimental fishing in Hirakud Reservoir, Orissa (1965-67)

The comparative efficiencies of simple gill net, vertical line net and framed net in exploiting the fishery of Hirakud Reservoir in Orissa were studied. Though comparatively costlier to fabricate, the framed net gave better results than the other two.

On the troll line investigations off Cochin during five fishing seasons. Pt. 3. Investigations during 1965-66 and 1966-67 seasons

During these two seasons investigations were carried out with a view to exploring the possibility of this operation on commercial basis and to study the effect of certain meteorological factors on catch.

A Study of Fan-Distortion Interaction Within the NASA Rotor 67 Transonic Stage

The performance of a transonic fan operating within nonuniform inlet flow remains a key concern for the design and operability of a turbofan engine. This paper applies computational methods to improve the understanding of the interaction between a transonic fan and an inlet total pressure distortion. The test case studied is the NASA rotor 67 stage operating with a total pressure distortion covering a 120-deg sector of the inlet flow field. Full-annulus, unsteady, three-dimensional CFD has been used to simulate the test rig installation and the full fan assembly operating with inlet distortion. Novel post-processing methods have been applied to extract the fan performance and features of the interaction between the fan and the nonuniform inflow. The results of the unsteady computations agree well with the measurement data. The local operating condition of the fan at different positions around the annulus has been tracked and analyzed, and this is shown to be highly dependent on the swirl and mass flow redistribution that the rotor induces ahead of it due to the incoming distortion. The upstream flow effects lead to a variation in work input that determines the distortion pattern seen downstream of the fan stage. In addition, the unsteady computations also reveal more complex flow features downstream of the fan stage, which arise due to the three dimensionality of the flow and unsteadiness. © 2012 American Society of Mechanical Engineers.

GaAs/Al（0.33）Ga（0.67）As短周期超晶格中能带不连续性随压力的变化

于2010-11-23批量导入

杉木人工林凋落物分解的研究

杉木是我国特有的速生针叶树种，栽培面积广泛（北纬21°41'－33°41'；东经102°-122°）。我国商品材的近1/4出自杉木人工林。杉木连栽地力衰退，生产力降低，是当前困扰杉木人工林发展的重大生产问题。在水热条件优越的亚热带山地，土壤肥力是影响林木持续保持高生产力的重要因素。因此，加速杉木人工林系统内养分循环是维持系统生产力稳定的关键，而凋落物分解又是养分循环的核心，于是对分解过程的调控便成为关键之关键。本研究的目的在于，探索促进杉木凋落物分解的途径，以增强林木自我培肥土壤的能力，为杉木人工林的可持续发展提供理论依据。研究所采用的实验材料全部来源于湖南省会同县广坪林区的中国科学院会同森林生态实验站。室内缩微模拟实验在英国陆地生态所完成，其它试验均在会同森林生态实验站进行。1. 杉木叶凋落物属难分解的凋落物，其原因是凋落物养分含量较低，尤其是N的含量偏低，为6.0mg.g~(-1)，仅为分解较快的桤木叶凋落物的41.6％；C/N比较高，为134.0，相当于桤木叶凋落物的2.38倍。杉木叶凋落物到第420天时的分解速率为43.3％，而桤木叶凋落物为67.2％。2. 根系凋落物也是杉木人工林生态系统凋落物的重要组分。杉木纯林细根年死亡量为497 kg.hm~(-2).a~(-1)，而火力楠人工纯林为595 kg.hm~(-2).a~(-1)。当火力楠与杉木混交后，细根年死亡量大幅度提高，达1149kg.hm~(-2).a~(-1)。杉木林死细根生物量年动态变化与地上部分生长规律基本一致。杉木细根象地上部分凋落物一样养分贫乏，除Ca以外，N、P、K、Mg分别比火力楠细根低53.0％、131％、595.9％、447.5％，而C/N比值高51.9％。杉木细根的年分解为32.78％，而火力楠为57.70％。因此，杉木纯林中通过细根归还的养分量相对较少，N、P、Ca、K、Mg归还量分别为0.32、0.007、0.58、0.52和0.83kg.hm~(-2)，而混交林中依次为2.59、0.046、1.87、6.06、7.86kg.hm~(-2)，大幅度增加。3. 杉木叶凋落物与阔叶树叶凋落物混合分解时表现出不同的相互作用形式。野外网袋法分解试验的结果表明，桤木与杉木叶凋落物混合分解，失重速率明显加快；火力楠与杉木叶凋落物分别以不同比例混合分解时，失重速率或强或弱得到促进；其它阔叶树并没有促进失重速率。除木荷外，其它阔叶树凋落物都不同程度地促进了Ca的释放。对于P，桤木和红栲，对于K，桤木和刺楸，明显促进了其释放，而其它阔叶树没有对这2种元素的释放产生任何作用。除木荷和樟树外，其它树种叶凋落物明显促进Mg的释放。实验中还发现，促进作用的强弱与阔叶树叶凋落物初始N含量高低有关。室内模拟实验中观察到的木荷叶凋落物明显抑制杉木叶凋落物分解的现象并没有在野外实验中发现。如果仅以凋落物分解过程中促进作用的强弱为标准选择杉木的混交林树种的话，选择这6种阔叶树的优先顺序为桤木、刺楸、红栲、火力楠、樟树、木荷。4. 本研究还用微型渗滤器进行模拟实验发现，投加NO_3-N促进了杉木叶凋落物的分解，在15周的时间分解速率提高2.38个百分点，而投加NH_4-N则未产生任何影响。投加NH_3－N和NH_4－N的负面效应是促进土壤养分的淋失。除Na~+以外，投加NH_4-N使NO_3-N、K~+、Ca~(2+)、Mg~(2+)的淋失明显增多。投加NO_3－N未明显合任何养分元素淋失增多。

Isospin symmetry breaking at high spins in the mirror pair Se-67 and As-67

Recent experimental data have revealed large mirror energy differences (MED) between high-spin states in the mirror nuclei Se-67 and As-67, the heaviest pair where MED have been determined so far. The MED are generally attributed to the isospin symmetry breaking caused by the Coulomb force and by the isospin-nonconserving part of the nucleon-nucleon residual interaction. The different contributions of the various terms have been extensively studied in the fp shell. By employing large-scale shell-model calculations, we show that the inclusion of the g(9/2) orbit causes interference between the electromagnetic spin-orbit and the Coulomb monopole radial terms at high spin. The large MED are attributed to the aligned proton pair excitations from the p(3/2) and f(5/2) orbits to the g(9/2) orbit. The relation of the MED to deformation is discussed.