Adding feedforward blade pitch control to standard feedback controllers for load mitigation in wind turbines

Combined feedback/feedforward blade pitch control is compared to industry standard feedback control when simulated in realistic turbulent winds. The feedforward controllers are designed to reduce fatigue loads, increasing turbine lifetime and therefore reducing the cost of energy. Two feedforward designs are studied: collective-pitch model-inverse feedforward using a non-causal series expansion and individual-pitch gain-scheduled shaped compensator. The input to the feedforward controller is a measurement of incoming wind speed, which could potentially be provided by LIDAR. Three of the designs reduce structural loading compared to standard feedback control, without reducing power production.     

VACON变频器在直驱型风力发电系统独立变桨中的应用可行性分析

直驱型风力发电系统是一种应用前景看好的变速恒频风力发电方案,为提高风能的利用率和风力发电经济效益,提高系统稳定性降低维修成本,迫切要求对风力机进行独立变桨控制。本文介绍了直驱型风力发电系统的拓扑原理和风力机的特性曲线,并以基于同步电动机的变桨执行机构为平台,介绍了Vacon NX型变频器的控制功能,并对其在独立变桨场合的应用可行性进行了分析,由Vacon NX系列变频器的各项参数和性能指标可知,其应用于变桨控制中是可行的,是实现高效、可靠独立变桨控制的良好途径之一。     

基于线性预测残差倒谱的多语音基音频率检测

本文提出了一种基于线性预测残差倒谱的多语音基音频率检测算法,该算法首先对混合语音信号进行线性预测分析,进而计算预测信号与原混合信号的残差,并对残差信号做倒谱变换,得到混合语音信号的线性预测残差倒谱;然后在该信号的残差倒谱中,结合图像处理的技术,利用语音信号基音倒频匹配法检测出多语音信号的基音频率;最后在基音标定的过程中,本文算法利用语音信号的连续特性,依据信号基音频率前后差距变化最小原则标记出各基音所属话者。实验结果表明,本文提出的算法在弱回声及无回声的情况下能快速有效地从单声道混合语音信号中检测出多语音基音信息。     

Statistical feature of pitch frequency distributions for robust speaker identification

This letter proposes an effective and robust speech feature extraction method based on statistical analysis of Pitch Prequency Distributions (PFD) for speaker identification. Compared with the conventional cepstrum, PFD is relatively insensitive to Additive White Gaussian Noise (AWGN), but it does not show good performance for speaker identification, even if under clean environments. To compensate this shortcoming, PFD and conventional cepstrum are combined to make the ultimate decision, instead of simply taking one kind of features into account.Experimental results indicate that the hybrid approach can give outstanding improvement for text-independent speaker identification under noisy environments corrupted by AWGN.     

基于船姿测量的舰载光电经纬仪视轴稳定方法研究

利用船姿测量仪和光学编码器测出视轴稳定初始时刻的纵横摇角度和经纬仪方位俯仰角度,通过坐标变换技术将稳定点从甲板坐标系转换到大地坐标系中.实时测量由舰船摇摆引起的纵横摇角度变化量和编码器角度变化量,计算出视轴稳定点在大地坐标系中的偏离误差.利用伺服控制系统有效地补偿该误差,由此达到舰载光电经纬仪视轴稳定的目的.实际舰载跟踪试验证明了本文设计的视轴稳定系统准确度高,能够较好地隔离船摇对经纬仪视轴稳定的影响.     

关于汉语/英语AMR语音编码参数统计特性的研究

自适应多速率（AMR）算法是第三代移动通信系统中语音业务所采用的语音编码标准。为研究AMR算法应用于汉语语音和英语语音所产生的差异，本文针对ARM语音编码算法的特点，在处理分析了大量汉语语音数据的基础上，对算法中的线谱频率（LSF）、基音周期等关键编码参数进行了比较并给出相应结合。本文的研究有助于AMR算法针对汉语语音的性能优化。     

Phonation Threshold Pressure Across the Pitch Range: Preliminary Test of a Model

This study sought to examine the specific relationship between phonation threshold pressure (PTP) and voice fundamental frequency (F(0)) across the pitch range. A published theoretical model of this relationship described a quadratic equation, with PTP increasing exponentially with F(0). Prospective data from eight adults with normal, untrained voices were collected. Subjects produced their quietest phonation at 10 randomly ordered pitches from 5% to 95% of their semitone pitch range at 10% intervals. Analysis included curve fitting for individual and group data, as well as comparisons to the previous model. The group data fit a quadratic function similar to that proposed previously, but the specific quadratic coefficient and constant values differed. Four of the individual subjects' data were best fit by quartic functions, two by quadratic functions, and one by a linear function. This preliminary study indicates that PTP may be minimal at a "comfortable" pitch rather than the lowest pitch tested, and that, for some individuals, PTP may be slightly elevated during the passaggio between modal and falsetto vocal registers. These data support the general form of the theoretical PTP-F(0) function for these speakers, and indicate the possibility of potential refinements to the model. Future studies with larger groups of male and female subjects across a wider age range may eventually reveal the specific nature of the function.     

一种基于小波变换和隐Markov模型的声调识别方法

本文给出了一种基于小波变换和隐Markov模型(HMM)的声调识别方法。根据小波变换检测信号突变的性质,充分利用多分辨率分析,准确可靠地实现了基音检测;采用分划Gauss混合(PGM)概率密度函数的HMM进行汉语声调识别,推导出用PGM函数的Viterbi算法的简化递推式。在匹配计算量大大减小的情况下,特定人的四声识别率为97.22％,非特定人达到94.47％。     

基于数据驱动的语音库的分析与构建

语音数据库和规则库是转换系统中最基本和重要的部分,在进行转换时,根据韵律建模的结果,从原始语音库中取出相应的语音基元,利用特定的语音合成技术对基元进行韵律调整合成。针对语音数据库和规则库的建立技术,在GPS嵌入式系统的语音库构建过程中,在与传统方法比较的基础上,给出了基于数据驱动的构建方法,并在特定平台RAM10上,对“文-语”转换技术中的瓶颈之一进行了探讨和实践。     

紫外-可见光谱测定马尾松纸浆树脂中甘油三酯含量

用紫外光谱法测定马尾松TMP浆和酸性亚硫酸盐浆正己烷抽出物中甘油三酯的含量,探讨了三油酸甘油酯标准物与纸浆树脂的紫外吸光谱图特征与特征峰位置以及测试时间对吸光度值的影响。结果表明,在实验试剂用量范围内,三油酸甘油酯在412 nm的吸光度与浓度成线性关系,线性相关系数为0.971;吸光度随测试时间呈线性降低关系,相关系数为0.990。再现性实验回收率98％～104％,精确度1.27％～4.03％。利用该方法测定了纸浆与酶处理后纸浆抽提物中甘油三酯的含量,评价了酶处理纸浆降解甘油酯的效果。马尾松TMP与酸性亚硫酸盐浆中甘油三酯含量较高,约占总抽提物的50％。酶处理后TMP浆与酸性亚硫酸盐浆中甘油三酯降解率分别达到46.31％和35.55％。