一种自动校准多风表的风洞检测试验装置

针对传统风表校准方式需多次手动调节风量、操作复杂、人工读数与绘图费时费力且校准精度低等问题,设计了一种自动校准多风表的风洞检测试验装置,介绍了该装置的结构及检测试验原理。试验结果表明,该装置风流稳定,可自动调节风量,操作简单,可1次校准多个风表,校准精度高,并能对校准结果进行记录、存储、处理,适合于低、中、高3档多风表自动校准。     

Calculation and characteristics analysis of blade pitch loads for large scale wind turbines

Based on the electric pitch system of large scale horizontal-axis wind turbines,the blade pitch loads coming mainly from centrifugal force,aerodynamic force and gravity are analyzed,and the calculation models for them are established in this paper.For illustration,a 1.2 MW wind turbine is introduced as a practical sample,and its blade pitch loads from centrifugal force,aerodynamic force and gravity are calculated and analyzed separately and synthetically.The research results showed that in the process of ro...     

Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbi...     

Satellite-based and mesoscale regression modeling of monthly air and soil temperatures over complex terrain in Turkey

Simple regression algorithms were developed to quantify spatio-temporal dynamics of minimum and maximum air temperatures (T_min and T_max, respectively) and soil temperature for a depth of 0-5 cm (T_soil-5cm) across complex terrain in Turkey using Moderate Resolution Imaging Spectroradiometer (MODIS) data at a 500-m resolution. A total of 762 16-day MODIS composites (127 images × 6 bands) between 2000 and 2005 were averaged over a monthly basis to temporally match monthly T_min, T_max, and T_soil-5cm from 83 meteorological stations. A total of 60 (28 temporally averaged plus 32 time series-based) linear regression models of T_min, T_max, and T_soil-5cm were developed using best subsets procedure as a function of a combination of 12 explanatory variables: six MODIS bands of blue, red, near infrared (NIR), middle infrared (MIR), normalized difference vegetation index (NDVI), and enhanced vegetation index (EVI); four geographical variables of latitude, longitude, altitude, and distance to sea (DtS); and two temporal variables of month, and year. The best multiple linear regression models elucidated 65% (RMSE = 5.9 °C), 65% (RMSE = 5.1 °C), and 57% (RMSE = 6.9 °C) of variations in T_min, T_max, and T_soil-5cm, respectively, under a wide range of T_min (−34 to 25 °C), T_max (0.2-47 °C) and T_soil-5cm (−9 to 40 °C) observed at the 83 stations.     

超声波传感技术的矿用多通道智能风速风向仪

针对国内矿井现阶段测风仪器产品测量精准度易受井下潮湿、多尘等复杂条件的影响,提出了一种矿用智能多通道风速风向仪.软件采用多平台分模块设计,利用多段拟合进行测量参数误差修正,将超声波传感器、干湿温度传感器、压力传感器、信号转换电路等集成在风速风向仪手持终端上,实现了风速、风向等待测环境参数的多通道快速精准测量与参数自主校准.通过在测试环境下与传统机械风表的对比测试,结果表明:平均测试误差仅为2.47%,测风效果与稳定性明显高于传统机械风表.     

地形漫游中数据块调度算法研究

在LOD(level-of-detail)算法基础上,提出处理视点相关的交互式大规模地形数据的方法.包括:分块策略对规则网格进行区域分割;通过输入的数据点构建自顶向下的四叉树结构,划分成不同的块层次;在实时漫游过程中,根据视点z轴坐标值的变化导致块层次的改变,重新调入相应数据块构造地形网格,以及当视点x,y轴坐标改变时进行块调度.实验证明了该算法的有效性.     

Adaptive back-stepping pitch angle control for wind turbine based on a new electro-hydraulic pitch system

A new electro-hydraulic pitch system is proposed to smooth the output power and drive-train torque fluctuations for wind turbine. This new pitch system employs a servo-valve-controlled hydraulic motor to enhance pitch control performances. This pitch system is represented by a state-space model with parametric uncertainties and nonlinearities. An adaptive back-stepping pitch angle controller is synthesised based on this state-space model to accurately achieve the desired pitch angle control regardless of such uncertainties and nonlinearities. This pitch angle controller includes a back-stepping procedure and an adaption law to deal with such uncertainties and nonlinearities and hence to improve the final pitch control performances. The proposed pitch system and the designed pitch angle controller have been validated for achievable and efficient power and torque regulation performances by comparative experimental results under various operating conditions.     

A multiple observers and dynamic weighting ensembles scheme for diagnosing new class faults in wind turbines

This paper presents an incremental way to design the decision module of a diagnostic system by resorting to dynamic weighting ensembles of classifiers. The method is applied for sensor fault detection and isolation in a doubly fed induction generator for wind turbine application. Three sets of observers are combined to generate residuals that are robust to operating point changes. These signals are progressively fed into a dynamic weighting ensembles algorithm, called Learn⁺⁺.NC, for fault classification. The algorithm incrementally learns the residuals–faults relationships and dynamically classifies the faults including multiple new classes. It resorts to a dynamically weighted consult and vote mechanism to combine the outputs of the base-classifiers.     

Iterative learning control applied to a non-linear vortex panel model for improved aerodynamic load performance of wind turbines with smart rotors

The inclusion of smart devices in wind turbine rotor blades could, in conjunction with collective and individual pitch control, improve the aerodynamic performance of the rotors. This is currently an active area of research with the primary objective of reducing the fatigue loads but mitigating the effects of extreme loads is also of interest. The aerodynamic loads on a wind turbine blade contain periodic and non-periodic components and one approach is to consider the application of iterative learning control algorithms. In this paper, the control design is based on a simple, in relative terms, computational fluid dynamics model that uses non-linear wake effects to represent flow past an airfoil. A representation for the actuator dynamics is included to undertake a detailed investigation into the level of control possible and on how performance can be effectively measured.     

山谷地形无线传感器网络DV-Hop定位算法研究

无线传感器网络在森林防火、目标追踪、灾难预警、环境监测等应用中,节点定位是关键技术之一。对山谷地形中无线传感器网络三维DV-Hop定位算法进行了研究。通过对三维DV-Hop定位算法误差分析,找出产生误差的主要原因,提出了相应的改进算法。仿真实验结果证明:改进后的算法提高了节点定位精度,并指出了在山谷地形应用三维DV-Hop定位算法时锚节点比例的参考值。     

带式压力传感器的大型风力机气动测试研究

介绍了一种新型带式压力传感器的设计方法及其在大型风力机的空气动力学基础研究中的应用。该传感器由电源模块、压力测试节点、数据采集与传输模块组成。压力测试节点中敏感头的输出信号通过调理芯片,确保每个节点输出的模拟信号准确可靠;数据采集与传输模块采用高速单片机,用12位高精度AD进行数据采集,并通过适配器将数据发送给上位机。该传感器经过试验取得比较满意的结果。     

Studies on a low Reynolds number airfoil for small wind turbine applications

In contrast to large horizontal axis wind turbines (HAWTs) that are located in areas dictated by optimum wind conditions, small wind turbines are required for producing power without necessarily the best wind conditions. A low Reynolds number airfoil was designed after testing a number of low Reynolds number airfoils and then making one of our own; it was tested for use in small HAWTs. Studies using XFOIL and wind tunnel experiments were performed on the new airfoil at various Reynolds numbers. The pressure...     

新翼型风力机叶片综合性能的实验研究

以自制新翼型风力机风轮为研究对象,在B1/K2直流式低速风洞完成自制新翼型风力机的功率特性测试实验,采用丹麦B＆K公司结构动态测试系统完成风轮结构动态特性实验,并与国内某公司同型号传统翼型的风力机进行气动特性、结构动态特性的对比分析,为下一步系统研究新翼型的气动特性和设计综合性能较优的风轮奠定了理论和实验基础.     

矿用风速传感器研究

研究了一种基于热膜式工作原理的煤矿专用风速传感器,传感器除具有风速测量功能外,还具有风流的温度测量功能和风流正反方向识别功能,芯片结构采用了冗余设计的思想,增加了风速敏感膜冷贮备系统,提高了产品可靠性[1],风速传感器采用恒温式工作原理,测量范围为0.1~15m/s,具有结构可靠、动态特性好、测量精度高的特点。     

Constraints on general motions for camera calibration with one-dimensional objects

This paper focuses on two problems in camera calibration with one-dimensional (1D) objects: (a) to find out the general motion patterns well suited for solving the calibration problem, and (b) to improve the robustness and accuracy of the method. Firstly, a sufficient and necessary condition for the solvability of 1D calibration with general motions is proved. Then the special motion of tossing a 1D object is provided as an example to illustrate the correctness and feasibility of this condition. After that some practical issues on obtaining the solution are inspected. By avoiding singularities, the precision and robustness of the method are improved: the relative mean errors are reduced to less than 5% at the noise level of one pixel which surpasses the state-of-the-art methods of the same category.     

基于虚拟仪器的热电偶自动计量检定系统

热电偶的检定是其使用过程中必不可少的工作环节。自动检定不仅工作效率高,而且可以提高检定准确度。虚拟仪器技术是计算机技术应用于仪器领域的最新成果,以虚拟仪器技术为基础,介绍了热电偶检定系统的新方法,使得热电偶的检定真正实现了自动化,同时,具有数字和图形显示方式,以及分析、打印和数据处理等多种功能,还阐述了系统的硬件结构和软件流程,并在实际应用中得到验证。     

峰值流量仪标定系统

峰值流量仪是家用的哮喘监控仪器。它在临床使用和标定时的差异使得测量结果不够精确。为了提高标定准确度,在分析气体流态的基础上建立了标定系统的数学模型,并应用该模型对新研制出的峰值流量仪进行了标定。     

MEMS陀螺仪参数校准方法研究

针对陀螺仪标定成本与精度之间矛盾的问题,建立了陀螺仪的误差模型,探索了一组最佳标定位置,提出了针对陀螺仪的零偏、标度因数和安装误差角等参数引起测量数据出现偏差的4位置标定方法.并将该方法应用于机载系统的姿态测量单元,估计出了陀螺的标定参数,并对标定后的陀螺仪进行试验测试.测试结果表明,标定后陀螺仪的性能满足预期试验要求,验证了该标定方法的正确性和有效性.     

基于单张平行六面体照片的摄像机标定方法

摄像机标定是计算机视觉的重要组成部分。根据射影几何理论建立了基于单张平行六面体照片的摄像机全参数标定方法。通过调和射影及Laguerre定理的推论求解出平面圆环点的共轭虚像,利用平行六面体照片存在的三对圆环点的虚像,构造对无穷远平面绝对二次曲线的像ω的约束,使用辗转相除法求解非线性问题。最后,给出该算法对模拟图像和真实照片的实验。实验结果表明计算结果与真实情况吻合。     

PETOOL: MATLAB-based one-way and two-way split-step parabolic equation tool for radiowave propagation over variable terrain

A MATLAB-based one-way and two-way split-step parabolic equation software tool (PETOOL) has been developed with a user-friendly graphical user interface (GUI) for the analysis and visualization of radio-wave propagation over variable terrain and through homogeneous and inhomogeneous atmosphere. The tool has a unique feature over existing one-way parabolic equation (PE)-based codes, because it utilizes the two-way split-step parabolic equation (SSPE) approach with wide-angle propagator, which is a recursive forward–backward algorithm to incorporate both forward and backward waves into the solution in the presence of variable terrain. First, the formulation of the classical one-way SSPE and the relatively-novel two-way SSPE is presented, with particular emphasis on their capabilities and the limitations. Next, the structure and the GUI capabilities of the PETOOL software tool are discussed in detail. The calibration of PETOOL is performed and demonstrated via analytical comparisons and/or representative canonical tests performed against the Geometric Optic (GO) + Uniform Theory of Diffraction (UTD). The tool can be used for research and/or educational purposes to investigate the effects of a variety of user-defined terrain and range-dependent refractivity profiles in electromagnetic wave propagation.

Program summary

Program title: PETOOL (Parabolic Equation Toolbox)Catalogue identifier: AEJS_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJS_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 143 349No. of bytes in distributed program, including test data, etc.: 23 280 251Distribution format: tar.gzProgramming language: MATLAB (MathWorks Inc.) 2010a. Partial Differential Toolbox and Curve Fitting Toolbox requiredComputer: PCOperating system: Windows XP and VistaClassification: 10Nature of problem: Simulation of radio-wave propagation over variable terrain on the Earth?s surface, and through homogeneous and inhomogeneous atmosphere.Solution method: The program implements one-way and two-way Split-Step Parabolic Equation (SSPE) algorithm, with wide-angle propagator. The SSPE is, in general, an initial-value problem starting from a reference range (typically from an antenna), and marching out in range by obtaining the field along the vertical direction at each range step, through the use of step-by-step Fourier transformations. The two-way algorithm incorporates the backward-propagating waves into the standard one-way SSPE by utilizing an iterative forward–backward scheme for modeling multipath effects over a staircase-approximated terrain.Unusual features: This is the first software package implementing a recursive forward–backward SSPE algorithm to account for the multipath effects during radio-wave propagation, and enabling the user to easily analyze and visualize the results of the two-way propagation with GUI capabilities.Running time: Problem dependent. Typically, it is about 1.5 ms (for conducting ground) and 4 ms (for lossy ground) per range step for a vertical field profile of vector length 1500, on Intel Core 2 Duo 1.6 GHz with 2 GB RAM under Windows Vista.