Combining information sources for confidence estimation with CRF models

Obtaining accurate confidence measures for automatic speech recognition (ASR) transcriptions is an important task which stands to benefit from the use of multiple information sources. This paper investigates the application of conditional random field (CRF) models as a principled technique for combining multiple features from such sources. A novel method for combining suitably defined features is presented, allowing for confidence annotation using lattice-based features of hypotheses other than the lattice 1-best. The resulting framework is applied to different stages of a state-of-the-art large vocabulary speech recognition pipeline, and consistent improvements are shown over a sophisticated baseline system. Copyright © 2011 ISCA.

淡水藻源异味化合物的光降解和光催化降解研究

为探讨利用太阳光降解水中异味化合物的可行性,对2-甲基异莰醇(MIB)、β-柠檬醛(β-Cyclocitral)和β-紫罗兰酮(β-Ionone)等3种异味化合物在紫外光和太阳光下的光降解及光催化降解效果进行了研究。结果表明,单波长紫外光——UVC(254 nm)和UVB(312 nm)及太阳光均能有效降解纯水中的β-Cyclocitral和β-Ionone,但不能降解MIB。加入纳米TiO2后,在UVC(254 nm)、UVB(312 nm)和太阳光照射下,MIB、β-Cyclocitral和β-Ion

武汉东湖鳜鱼生长速率及与其它几种养殖鱼类对水质影响的比较研究

“八五”国家攻关课题85-908-01-03-02

微囊藻和栅藻共培养实验及其竞争参数的计算

以Ｌｏｔｋａ－Ｖｏｌｔｅｒｒａ 的双种竞争模型为基础，进行试验设计。共培养试验中，两种藻类的增长行为是不同的，培养前期共培养中栅藻的数量大于纯培养中栅藻的数量，而在后期则相反，微囊藻则是在整个共培养过程中的数量都小于纯培养中的数量。通过纯培养取得参数Ｋ 和ｒ，变模型的微分形式为差分形式，以生长曲线拐点（密度制约起始点）出现的时间作为计算竞争参数的起始时间。经模拟计算获得竞争参数，表明微囊藻对栅藻的抑制能力是栅藻对微囊藻抑制能力的７倍。并以此作为微囊藻可能爆发成为“水华”的理由之一。应用所得的参数，拟合共培

鳜消化器官的组织学观察

“八五”国家科技攻关项目85-908-01-03-02

富营养浅湖水生植被重建对底栖动物的影响

利用在极富营养型的浅水湖泊所建立的大型实验围隔系统，对水生植被恢复后底栖动物群落的变化作了为期3a的研究．4个围隔和大湖对照点共采集到底栖动物38种，Ⅰ、Ⅱ和Ⅲ号围隔人工恢复沉水植被后，水质得到明显的改善，底栖动物群落结构发生明显的变化：其种类项目、个体密度和生物量增加，软体动物重新出现，生物多样性提高．对底栖动物与水生植物之间的相互关系也作了探讨．

武汉东湖水生植被的恢复试验研究

本文报道了在武汉东湖所作的水生植被恢复的研究结果．分别在东湖水果湖、汤林湖和后湖等三个湖建立水生植被恢复示范区．挺水植物莲Nelumbonucifera和芦苇Phragmitescommumis、浮叶植物菱Trapasp．和r－选择型的沉水植物苦草Vallisneriasp．、聚草Myriophyllumspicatum、菹草Potamogetoncrispus和大茨藻Najasmarina等在三个植被复示范区均可以恢复．而黄丝草Potamogetonmaackianus、伊乐藻Elodeacanaden

武汉东湖不同营养型子湖的水生生物与水域功能

于1991－1993年研究了武汉东湖4个营养型不同的子湖中水生生物与水域功能，表明各子湖之间各类水生生物的生态特征存在明显差异。茶港湾的HBC和FC的数量、藻类的细胞密度和初级生产量、浮游动物和底栖动物的个体密度等均居4个子湖之首，其水质已达到超富营养水平，将该湖区作为污水天然净化区进行管理，可望对东湖的主体湖区起到缓冲和保护作用；郭郑湖的水质状况仅次于茶港湾湖区，处于富营养阶段，该湖区多项生化指标已不符合饮用水源和养殖水体的要求，以发展水上运动和旅游事业为主要功能较为适宜；后湖的营养水平介于中-富营养和

富营养化浅水湖泊沉水水生植被的衰退与恢复

对国外近年来有关富营养化浅水湖泊的退化与恢复方面的研究进展以及生物操纵作用作了述评．对有关富营养化湖泊沉水植被衰退的有代表性的3种假说也作了介绍．根据“八五”期间武汉东湖水生植被重建的研究工作和多年积累的湖泊水生植被调查资料，提出了长江中下游浅湖富营养化过程中沉水植技演替的模式．

武汉东湖水生植物生态学研究 Ⅱ.后湖水生植被动态与水体性质

报道1991～1993年武汉东湖子湖后湖区水生植被和水体理化性质的调查结果。目前后湖水生植物较东湖其它湖区丰富，共记载了47种，3年间水生植物生物量和水生植被分布面积变动剧烈。1991年水生植被分布面积约为该湖区面积的8．4％；1992年高达381hm2，覆盖面积达80％；而1993年水生植被面积不到1％。经分析，认为目前影响后湖水生植被的主要因子是草食性鱼类，只要停止放养草食性鱼类，结合降低水位和人工引种等措施，可以促进沉水植物迅速恢复。并对沉水植物和浮游植物分别占优势的状态下水体的性质作了比较。

武汉东湖主要湖区的藻类与营养型评价

对东湖9个湖区藻类的群落结构、生长潜力、初级生产力和营养状况进行了比较研究。结果表明,9个湖区藻类的种类组成无明显差异,绿藻为主,蓝藻和硅藻次之;藻类的生长潜力和初级生产力各湖区差异较大,均以茶港湾重污染区最高和牛巢湖最低。根据各项指标综合分析,9个湖区水质优劣的顺序是:牛巢湖、汤林湖、后湖、郭郑湖、菱角湖、筲箕湖、庙湖、喻家湖和茶港湾重污染区。对东湖的大水面郭郑湖40年来藻类的有关参数进行比较发现,藻类个体数量的峰值40年内增加了百倍以上,而藻类的属数却比50年代减少了一半,藻类多样性下降,种类小型化现

Phase perfection in zinc Blende and Wurtzite III-V nanowires using basic growth parameters.

Controlling the crystallographic phase purity of III-V nanowires is notoriously difficult, yet this is essential for future nanowire devices. Reported methods for controlling nanowire phase require dopant addition, or a restricted choice of nanowire diameter, and only rarely yield a pure phase. Here we demonstrate that phase-perfect nanowires, of arbitrary diameter, can be achieved simply by tailoring basic growth parameters: temperature and V/III ratio. Phase purity is achieved without sacrificing important specifications of diameter and dopant levels. Pure zinc blende nanowires, free of twin defects, were achieved using a low growth temperature coupled with a high V/III ratio. Conversely, a high growth temperature coupled with a low V/III ratio produced pure wurtzite nanowires free of stacking faults. We present a comprehensive nucleation model to explain the formation of these markedly different crystal phases under these growth conditions. Critical to achieving phase purity are changes in surface energy of the nanowire side facets, which in turn are controlled by the basic growth parameters of temperature and V/III ratio. This ability to tune crystal structure between twin-free zinc blende and stacking-fault-free wurtzite not only will enhance the performance of nanowire devices but also opens new possibilities for engineering nanowire devices, without restrictions on nanowire diameters or doping.

The rocking response of large flexible structures to earthquakes

The rocking response of structures subjected to strong ground motions is a problem of 'several scales'. While small structures are sensitive to acceleration pulses acting successively, large structures are more significantly affected by coherent low frequency components of ground motion. As a result, the rocking response of large structures is more stable and orderly, allowing effective isolation from the ground without imminent danger of overturning. This paper aims to characterize and predict the maximum rocking response of large and flexible structures to earthquakes using an idealized structural model. To achieve this, the maximum rocking demand caused by different earthquake records was evaluated using several ground motion intensity measures. Pulse-type records which typically have high peak ground velocity and lower frequency content caused large rocking amplitudes, whereas non-pulse type records caused random rocking motion confined to small rocking amplitudes. Coherent velocity pulses were therefore identified as the primary cause of significant rocking motion. Using a suite of pulse-type ground motions, it was observed that idealized wavelets fitted to velocity pulses can adequately describe the rocking response of large structures. Further, a parametric analysis demonstrates that pulse shape parameters affect the maximum rocking response significantly. Based on these two findings, a probabilistic analysis method is proposed for estimating the maximum rocking demand to pulse-type earthquakes. The dimensionless demand maps, produced using these methods, have predictive power in the near-field provided that pulse period and amplitude can be estimated a priori. Use of this method within a probabilistic seismic demand analysis framework is briefly discussed. © 2013 Springer Science+Business Media Dordrecht.

Observation of the third subband population in modulation-doped InGaAs/InAlAs heterostructure

The population of the third (n = 3) two-dimensional electron subband of InGaAs/InAlAs modulation-doped structures has been observed by means of Fourier transform photoluminescence (PL). Three well resolved PL peaks centred at 0.737, 0.908, and 0.980eV are observed, which are attributed to the transitions from the lowest three electron subbands to the n = 1 heavy-hole subband. The subband separations clearly exhibiting the features of the stepped quantum well with triangle and square potentials are consistent with numerical calculation. Thanks to the presence of Fermi cutoff, the population ratio of these three subbands can be estimated. Temperature- and excitation-dependent luminescences are also analyzed.