基于小波变换的语音信号基音周期估计

基音周期是语音信号最重要的参数之一，是进行语音信号数字处理的基础。小波变换具有良好的时频分辨率，为语音信号基音周期提取提供了新的途径。基于小波变换及其多尺度边缘检测的基本特性，阐述了语音信号基音周期估计的原理、实现方法、算法流程；并给出了实验结果。实验表明：该方法可以实现大动态范围的语音信号基音周期估计计算，并可获得满足实用的较为精确的结果。     

液压钳制器的螺栓力学分析

针对某款液压常闭型钳制器提供钳制力的螺栓,分析其受力情况与安全系数,验证了车去中段螺纹的螺栓直径为9mm的光杆部分能够承受钳制器所需要的巨大的钳制力,但是在重新设计时,应当将光杆部分的直径尽量取得大一些,保证螺杆不会被拉坏。同时验证了大径为12mm的螺栓,各螺距对螺纹强度影响不大,并给出了不同大径不同螺距的普通螺纹危险截面的切应力与弯曲应力的计算公式,为替换其他标准和选用合适的国标普通螺纹提供了理论依据。     

基于时域自相关平方函数的基音周期估计

语音信号的基音估计算法多年来一直是人们关注的问题。属于时域法的基于短时自相关函数的基音估计方法以其算法简单、计算量小而成为人们首选的算法。论文在此法的基础上,提出了一种基于时域自相关平方函数的基音周期估计方法。通过实验仿真表明,该方法简单易行,基音周期估计的准确性比较高。     

γ树脂提取方式及含量对煤沥青润湿性能的影响

为改善煤沥青的润湿性能,分别以甲苯、苯、二甲苯为溶剂,改质煤沥青为基体,萃取获得甲苯提取物、苯提取物、二甲苯提取物,利用FT-IR结合TG-DTG研究3种提取物的化学结构与热解特性。结果显示3种溶剂提取物的红外光谱图及TG-DTG曲线基本相似,可以认为3种提取物基本相似。将3种提取物分别与改质煤沥青按照不同比例混合制备改性沥青,研究γ树脂提取方式和含量对改性沥青软化点、结焦值以及润湿性能的影响,结果表明,随着提取物含量的增加,改性沥青的软化点、结焦值均有所降低,接触角降至0°的时间缩短,3种提取物均会降低改性沥青的软化点和结焦值,改善煤沥青的润湿性能。     

锥齿轮齿距及齿形偏差测量与分析方法

研究了基于齿轮测量中心的锥齿轮齿距偏差和齿形偏差测量与分析方法及其实现技术。该方法应用齿轮啮合理论,根据锥齿轮齿面成形方法,建立了齿面几何参数计算模型;在齿面上建立测量网格,控制齿轮测量中心四轴运动使齿面和测头于测量网格点接触,采集实际坐标轴及测头读数;应用B样条法构造实际齿面,计算其齿形偏差。在此基础上,开发了基于哈量集团公司制造的390X系列齿轮测量中心的实现软件系统。30家锥齿轮制造企业实际应用表明,该软件系统为提高锥齿轮精度、减小齿形偏差提供了先进的测量与分析手段。     

兆瓦级风力发电机组变桨距控制系统研究

分析和建立了兆瓦级风力发电机组各个部分机理模型以及有效风速的模型,针对变桨距风力发电机组在低风速最大风能捕获和高风速额定功率保持的控制目标,建立数学模型。并应用MATLAB对PID控制器下的系统模型进行仿真,结果表明模型的可行性。     

Evaluating techniques for redirecting turbine wakes using SOWFA

Wind plant control is an active field of research in which controllers are developed that seek to maximize overall wind-plant performance in terms of power production, turbine structural loads, or both. Such control strategies are often different from those that are optimal for an individual turbine. One type of wind-plant control method is to redirect the wakes of upstream turbines so that they avoid downstream turbines. In this paper, we investigate several possible methods for redirecting turbine wakes, including some existing and some novel approaches. The methods are compared in terms of their ability to redirect turbine wakes and their effects on turbine power capture and structural loads using the high-fidelity wind plant simulation tool Simulator for On/Offshore Wind Farm Applications (SOWFA).     

环氧煤焦沥青管道防腐涂料应用

介绍了环氧煤沥青防腐涂料的基本组成、基本性能、基本技术指标,以及在管道防腐施工应用中的基本要求和注意事项。     

Airfoil optimisation for vertical‐axis wind turbines with variable pitch

To advance the design of a multimegawatt vertical‐axis wind turbine (VAWT), application‐specific airfoils need to be developed. In this research, airfoils are tailored for a VAWT with variable pitch. A genetic algorithm is used to optimise the airfoil shape considering a balance between the aerodynamic and structural performance of airfoils. At rotor scale, the aerodynamic objective aims to create the required optimal loading while minimising losses. The structural objective focusses on maximising the bending stiffness. Three airfoils from the Pareto front are selected and analysed using the actuator cylinder model and a prescribed‐wake vortex code. The optimal pitch schedule is determined, and the loadings and power performance are studied for different tip‐speed ratios and solidities. The comparison of the optimised airfoils with similar airfoils from the first generation shows a significant improvement in performance, and this proves the necessity to properly select the airfoil shape.     

An improved reduced-order model of an electric pitch drive system for wind turbine control system design and simulation

To obtain satisfactory dynamic characteristics and enhance numerical simulation efficiency, an improved reduced-order transfer-function model of an electric pitch drive system (EPDS) for a wind turbine is proposed. First, a detailed transfer-function model of an EPDS is developed on the basis of its mathematical model. Thereafter, the improved reduced-order transfer-function model for an EPDS is derived from the detailed model by transfer-function approximation, sensitivity analysis, and block diagram reduction. The frequency-domain characteristics of the proposed model and their effects on the stability of the pitch angle control system are also analyzed and compared with that of a first-order transfer-function model. Finally, the dynamic characteristics of an EDPS using the improved model are analyzed and verified by a practical EPDS test platform. Furthermore, based on the FAST–MATLAB/Simulink co-simulation tool, simulation comparisons are performed on the loading characteristics of a wind turbine to further validate its availability in it. Results show that the improved model is superior to the first-order model for the performance analysis of a wind turbine pitch angle controller, and it also can meet the requirements of large-scale loading simulations for wind turbines both in terms of the precision and the time efficiency.