BLS polarization-induced performance degradation in WDM-PON systems based on wavelength-locked FP-LDs

We experimentally investigated the performance degradation due to broadband light source (BLS) polarization in wavelength-division multiplexing-passive optical network systems based on a wavelength-locked Fabry-Perot laser diode. The results showed that the BLS polarization difference between two polarization states should be less than 3 dB, and its injection power should be greater than −18 dBm for a received-power penalty of less than 1 dB.     

Whale 3D monitoring using astrophysic NEMO ONDE two meters wide platform with state optimal filtering by Rao-Blackwell Monte Carlo data association

This paper proposes an algorithm for whale monitoring by passive acoustic using four short-spaced hydrophones. It is successfully tested on the NEutrino Mediterranean Observatory - Ocean Noise Detection Experiment (NEMO ONDE) underwater acoustic platform. In past years, interest in marine mammals has increased, leading to the development of passive acoustic methods of localization which permits to study whales’ behavior in deep water (several hundreds of meters) without interfering with the animals. In this paper, we propose a robust Angle of Arrival (AoA) tracking algorithm, which provides an estimation of elevation and azimuth angles in spite of the short distance between hydrophones, which does not allow direct 3D localization. Moreover we show that, in some cases, the time-delay between direct signal and its reflection on the sea surface allows the range estimation, and thus the exact localization of the whale. The classic AoA estimation is performed with a non-linear regression, and it is compared with a more sophisticated algorithm, the Rao-Blackwell Monte Carlo Data Association. We demonstrate that the second method is very robust to the presence of clutter. According to the Pavi 2009 workshop challenge, our algorithm is the only one performing relevant tracks of whale.     

被动遥测光谱仪仪器响应函数的实验测定研究

被动遥测光谱技术在目标光谱探测、大气痕量气体监测等方面都有广泛的应用.为了得到准确和高灵敏度的遥测光谱测试数据,被动遥测光谱设备必须首先进行响应函数的测量,以消除仪器本身热量对测量数据的影响.利用标准高温黑体对BLUKER TENSOR 37型被动式FTIR光谱仪仪器响应函数进行了测定,得到了该型仪器在不同温度区间MCT探测器和InSb探测器仪器的响应函数和背景函数.实验发现MCT探测器响应函数随温度升高而增加,而InSb探测器则相反,随温度升高略有减小.背景函数不仅与背景相关,还与温度相关.MCT探测器背景函数随温度的升高而减小,而InSb探测器则相反,随温度升高而增加.     

被动多轴DOAS技术污染气体垂直柱浓度反演方法研究

介绍了基于太阳散射光的多轴被动差分吸收光谱技术与系统及其在大气污染气体垂直柱浓度监测中的应用.实验中利用夫琅和费光谱作为参考光谱,同时将Ring光谱作为一种吸收结构参与拟合去除太阳光谱中的夫琅和费结构和Ring效应对测量结果的影响,并结合辐射传输模型将污染气体斜柱浓度转换为垂直柱浓度,通过“好运北京”奥运限车期间与OMI卫星的对比实验一致得出限车期间NO2有约20％的下降,证实了本方法的可行性.     

一种具有主次标签的多标签文本分类方法

在自然语言文本分类处理领域中,各种主流的多标签分类方法都只能使文本具有多个标签类别,但并不能识别哪个标签对使用者来说最重要,哪些标签次重要。本文以文本信息为研究对象,通过对几种主流多标签分类算法原理的研究分析,提出了能识别主、次标签的多标签文本分类方法 -具有主次标签的多标签分类方法(Multi-Labels Text Classifier with Primary and Secondary Labels:MLTCPSL)。     

Structural control of floating wind turbines

The application of control techniques to offshore wind turbines has the potential to significantly improve the structural response, and thus reliability, of these systems. Passive and active control is investigated for a floating barge-type wind turbine. Optimal passive parameters are determined using a parametric investigation for a tuned mass damper system. A limited degree of freedom model is identified with synthetic data and used to design a family of controllers using H_∞ multivariable loop shaping. The controllers in this family are then implemented in full degree of freedom time domain simulations. The performance of the passive and active control is quantified using the reduction in fatigue loads of the tower base bending moment. The performance is calculated as a function of active power consumption and the stroke of the actuator. The results are compared to the baseline and optimal passive system, and the additional achievable load reduction using active control is quantified. It is shown that the optimized passive system results in tower fore-aft fatigue load reductions of approximately 10% compared to a baseline turbine. For the active control, load reductions of 30% or more are achievable, at the expense of active power and large strokes. Active control is shown to be an effective means of reducing structural loads, and the costs in power and stroke to achieve these reductions are demonstrated.     

泛在网络中基于标签标识的应用与业务需求

介绍了泛在网络中基于标签标识的应用和业务的概念、组成要素、应用场景分类，并对相关业务和能力需求进行了分析和探讨。     

Analysis of steady-state response regimes of a helicopter ground resonance model including a non-linear energy sink attachment

Helicopter Ground Resonance is a dynamic instability involving the coupling of the blades motion in the rotational plane (i.e. the lag motion) and the motion of the fuselage. This paper presents a study of the capacity of a Non-linear Energy Sink to control a Helicopter Ground Resonance. A model of helicopter with a minimum number of degrees of freedom that can reproduce Helicopter Ground Resonance instability is obtained using successively Coleman transformation and binormal transformation. A theoretical/numerical analysis of the steady-state responses of this model when a Non-linear Energy Sink is attached on the fuselage in an ungrounded configuration is performed. The analytic approach is based on complexification-averaging method together with geometric singular perturbation theory. Four steady-state responses are highlighted and explained analytically: complete suppression, partial suppression through strongly modulated response, partial suppression through periodic response and no suppression of the Helicopter Ground Resonance. A systematic method based on simple analytical criterions is proposed to predict the steady-state response regimes. The method is finally validated numerically.     

支持Web2.0标签层次体系构建的关系识别及层次组合方法研究

从标签系统中生成层次体系可以支持多种类型的应用，具备重要的意义.当前的研究主要集中于发现标签间的关系，但对如何利用这些关系形成高质量的层次体系却关注不足.针对这一现状，研究了支持Web 2.0标签层次体系构建的关系识别及层次组合方法，通过分析并识别已发现的标签间关系所具有的不同类型提升了标签间关系的质量，并提出基于语义流动分析的层次组合方法实现了更高质量的层次体系构建.应用多种评估指标的实验结果表明应用关系识别及使用语义流分析方法可以获得相比评估方法更高质量的标签层次体系.     

Experimental results on chatter reduction in turning through embedded piezoelectric material and passive shunt circuits

Chatter instability is an important drawback concerning high precision and accurate machining operations. Suitable strategies for chatter detection and reduction should be proposed and exploited in order to ultimately improve the final quality of machined parts. It is well known that chatter instability can be reduced by increasing damping since the later presents a proportional relationship with stability limits. The main idea in the present work is to address the issue of chatter instability by proposing a vibration reduction methodology through the use of embedded piezoelectric patches in the tool-holder connected to a passive shunt electrical circuit. This circuit is responsible for energy dissipation providing extra damping to the system. The strategy is numerically and experimentally tested in turning/boring operations. A simplified electro-mechanical distributed-parameter model is briefly described and numerically evaluated in order to assess the potentiality of the proposed technique. Actual measured frequency response functions of the tool-holder with different shunt strategies are compared demonstrating how damping can be modified. Moreover, two different shunt strategies are evaluated during a boring operation. Preliminary experimental results point to a considerable improvement in the quality of the surface finishing when the proposed passive shunt circuits associated to the piezoelectric elements are used, indicating that the proposed strategy can be a promising and feasible solution for chatter reduction. Nevertheless, there are still some technical difficulties that should be overcome towards the full practical implementation of the proposed methodology.