DC ice-melting model for wet-growth icing conductor and its experimental investigation

Icicles are often formed under the downside surface of conductor in the wet growth icing of overhead power line. When the ice deposit around overhead power line is molten by Joule heat produced by current, the pattern of heat transfer of ice deposit with icicles is dissimilar to that without icicle, so the ice-melting model for the columnar icing conductor cannot be applied to icicle-shaped icing conductor. According to the heat-transfer characteristic of the icicle-shaped icing conductor, this paper puts forward a DC ice-melting model for the icicle-shaped icing conductor. Because this full model includes three-dimensional heat-transfer and interface movement, which cannot be solved in closed form, a finite element scheme in space-domain and a finite difference scheme in time-domain are employed to discretize the governing equations. Firstly the whole ice-melting process on the icicle-shaped icing conductor is simulated by this model. Then the simulated results are validated by ice-melting experiments in the artificial chamber. The study from the model and the experiments shows that the size and length of icicle as well as the space between the adjacent icicles are factors to affect ice-melting. With the shorter icicle space, the bigger icicle size and the longer icicle-length, the surface of ice layer is enlarged and then more heat is taken away by the convection and radiation, so the ice melting time will get longer.

Research on the Icing Diagnosis ofWind Turbine Blades Based on FS–XGBoost–EWMA

In winter,wind turbines are susceptible to blade icing,which results in a series of energy losses and safe operation problems.Therefore,blade icing detection has become a top priority.Conventional methods primarily rely on sensor monitoring,which is expensive and has limited applications.Data-driven blade icing detection methods have become feasible with the development of artificial intelligence.However,the data-driven method is plagued by limited training samples and icing samples;therefore,this paper proposes an icing warning strategy based on the combination of feature selection(FS),eXtreme Gradient Boosting(XGBoost)algorithm,and exponentially weighted moving average(EWMA)analysis.In the training phase,FS is performed using correlation analysis to eliminate redundant features,and the XGBoost algorithm is applied to learn the hidden effective information in supervisory control and data acquisition analysis(SCADA)data to build a normal behavior model.In the online monitoring phase,an EWMA analysis is introduced to monitor the abnormal changes in features.A blade icing warning is issued when themonitored features continuously exceed the control limit,and the ambient temperature is below 0℃.This study uses data fromthree icing-affected wind turbines and one normally operating wind turbine for validation.The experimental results reveal that the strategy can promptly predict the icing trend among wind turbines and stably monitor the normally operating wind turbines.

Heat Transfer Analysis on Wire Icing and the Current Preventing from Icing

This study concerns the heat transfer processes during ice accretion on wires. The steady state heat balance equation assumed to describe the thermodynamics at the surface of a current heated wire subjected to icing is obtained by analyzing and computing each terms of heat flux. The surface temperature of wire is derived from the heat balance equation, which gives out a proposed estimation of the current intensity to prevent the wire icing

多光谱图像融合的IC器件表面缺陷检测

针对单可见光或单红外条件下的IC器件表面缺陷对比度不足,缺陷检测精度低的问题,提出多光谱图像融合的IC器件表面缺陷检测方法。针对IC器件可见光与红外图像配准中存在尺度不一致和对比度反转问题,引入拉普拉斯金字塔和特征描述符重组策略改进ORB(Oriented FAST and Rotated BRIEF)图像配准算法。在图像配准的基础上,提出NSST_VP图像融合方法,以非下采样剪切波变换(Non-Subsample Shearlet Transform, NSST)得到红外图像和已配准可见光图像的低频和高频子带,对低频子带采用视觉显著图(Visual Significance Map, VSM)加权融合规则,高频子带则采用自适应脉冲耦合神经网络(PA-Pulse Coupled Neural Network, PA-PCNN)决策融合规则,进而通过NSST逆变换得到高质量多光谱融合图像。最后,将融合图像输入YOLOv8s模型进行检测。实验结果表明,改进ORB的图像配准平均精度为87.8%,比ORB图像配准精度提高了62%,NSST_VP图像融合算法在主观视觉效果和客观评价指标上均有所提高。在缺陷检测实验中,NSST_VP融合方法的均值平均精度(mean Average Precision, mAP)达到83.15%,比单可见光、单红外缺陷图像检测的mAP分别提高了22.97%,28.31%,比双树复小波变换融合、曲线变换融合、非下采样轮廓波变换融合方法的mAP分别提高了13.14%,15.01%,20.35%。

带有左正则带的IC拟适当半群研究

文章利用富足半群上的L^(*)和R^(*)关系,得到了带有左正则带的IC拟适当半群的若干性质,特别是研究了幂等元导出的一类自同态映射。构造了半群上的一类好同余,将商半群简化为型-A半群,组建了一种具有半直积结构的AGC-系统,以此给出了带有左正则带的IC拟适当半群的一般刻画,改进了现有文献的部分结果。

IC厌氧反应器处理技术的应用研究及发展

IC厌氧反应器是第三代厌氧反应器,已广泛应用于高浓度有机废水处理。介绍了厌氧生物处理技术的特点及厌氧生物反应器的发展,重点介绍了IC厌氧反应器的构造、反应原理、特点、应用现状及发展趋势等,以期为IC厌氧反应器的应用提供参考。

基于阀切换UHPLC-IC联用技术的实验教学探索

具有阀切换的超高效液相色谱-离子色谱联用(UHPLC-IC)技术适用于同时分析含有机物和无机阴离子的样品,该联用技术简化了前处理的过程,消除了复杂基体,对无机阴离子进行富集,实现有机物和无机阴离子的同时分析,提高了色谱分析效率。将阀切换UHPLC-IC联用技术引入到本科生仪器分析实验课堂中,加深了学生对新型分析技术独特优势的理解,提高了本科生解决复杂实际问题的能力,拓宽和提升了仪器分析实验的教学内涵,有利于创新性和综合性人才的培养。

IC卡数据驱动下的公交客流分布及线路优化策略研究

为提升公交车的运营效率,研究以某市公交IC数据为基础,对公交客流进行分析,并提出基于遗传算法改进的公交线路优化模型。研究发现,该市全天公交客流出现早晚两个峰值段。工作日到节假日,客流集中地从市中心附近转变为旅游景点、公园和购物中心等地区。公交线路优化模型将某公交线路的利用率提高了15%,将乘客的平均等待时间降低了21%,有效提高了公交系统的运营效率和乘客满意度。此次研究为提升公交运营效率、改善乘客体验、优化城市交通结构、促进城市可持续发展提供重要依据和方法。

基于ICS算法的列车运动模型参数辨识

列车运动模型参数辨识对其运行控制至关重要,文章采用单质点列车模型,对运行列车进行受力分析,建立列车运动模型,并提出利用改进的布谷鸟搜索(ICS)算法对列车基本阻力参数进行辨识;基于真实的列车运行数据,对基本阻力参数辨识进行仿真分析,并基于TD3算法对参数辨识的有效性进行仿真验证。仿真结果表明,基本阻力参数辨识对列车运行控制十分必要,相对于经验参数,辨识参数下的列车基本阻力更为准确,且辨识参数下的牵引能耗有一定的降低。

APPLICATION OF CFD TECHNOLOGY IN WIND TURBINE ICING PROBER DESIGN

A series of numerical methods,which are suitable to design the shape and configuration of the icing prober for the horizontal axis wind turbine,are presented.The methods are composed of a multiple reference frame(MRF)method for calculating flow field of air,a Lagrangian method for computing droplet trajectories,an Eulerian method for calculating droplet collection efficiency,and an arithmetic for fast computing ice accretion.All the numerical methods are based on the computational fluid dynamics(CFD)technology.After proposing the basic steps and ideas for the design of the icing detection system,the shape and configuration of the icing prober for a 1.5 MW horizontal axis wind turbine are then obtained with the methods.The results show that the numerical methods are efficient and the CFD technology plays an important role in the design process.

基于ICA的锂电池SOH估计曲线确定方法研究

针对如何提取容量增量(IC)曲线上更有效的特征参数进行锂电池健康状态(SOH)估计问题,提出了一种基于修正的洛伦兹电压容量(RL-VC)模型。首先使用传统滤波方法对锂电池进行容量增量分析(ICA)。然后使用RL-VC模型进行对比,获得相应的特征参数并计算容量建模误差。在基于自主搭建的试验平台上获得的试验数据与开源数据集NASA中的动态数据集NCM中分别进行试验。VC容量建模的误差分别在0.23%和0.16%以内。RL-VC模型拟合的IC曲线提取的特征参数与锂电池容量高度线性相关,为后续SOH工作奠定了基础。基于RL-VC模型的IC分析方法相较于传统滤波方法,不仅在电池老化方面具有更高的鲁棒性,同时在特征参数提取方面避免了主观性和不确定性。

Observational Study on the Supercooled Fog Droplet Spectrum Distribution and Icing Accumulation Mechanism in Lushan, Southeast China

A fog monitor, hotplate total precipitation sensor, weather identifier and visibility sensor, ultrasonic wind speed meter,an icing gradient observation frame, and an automated weather station were involved in the observations at the Lushan Meteorological Bureau of Jiangxi Province, China. In this study, for the icing process under a cold surge from 20–25 January2016, the duration, frequency, and spectrum distribution of agglomerate fog were analyzed. The effects of rain, snow, and supercooled fog on icing growth were studied and the icing and meteorological conditions at two heights(10 m and 1.5 m)were compared. There were 218 agglomerate fogs in this icing process, of which agglomerate fogs with durations less than and greater than 10 min accounted for 91.3% and 8.7%, respectively. The average time interval was 10.3 min. The fog droplet number concentration for sizes 2–15 μm and 30–50 μm increased during rainfall, and that for 2–27 μm decreased during snowfall. Icing grew rapidly(1.3 mm h-1) in the freezing rain phase but slowly(0.1 mm h-1) during the dry snow phase. Intensive supercooled fog, lower temperatures and increased wind speed all favored icing growth during dry snow(0.5 mm h-1). There were significant differences in the thickness, duration, density, and growth mechanism of icing at the heights of 10 m and 1.5 m. Differences in temperature and wind speed between the two heights were the main reasons for the differences in icing conditions, which indicated that icing was strongly affected by height.

Study on Characteristics and Climatic Causes of Guangxi Conductor Icing

The icing disaster data and field investigation data of conductor icing were analyzed,the results indicated that conductor icing is mostly mixed freezing of glaze and rime in Guangxi,it becomes more severe with the higher of latitude and the increasing of altitude;the thickness of windward side is larger than leeward side in the same elevation.The closer to reservoir and rivers,the more serious the icing degree is.When cold wave broke,southwest warm-moist airflow was transported like an endless stream to the upper air of South China and surface stationary front sustained in South China coast.The main reasons of coming into being conductor icing were a stable strong frontal zone sustained in the upper air in Guangxi and there was strong inversion layer in the middle and lower troposphere,at that time,it was easy to generate conductor icing.The terrain generated an important effect on conductor icing.

Numerical Forecasting of Icing on Structural Components of Offshore Platforms in Polar Regions

The Polar Regions are rich in natural resources but experience an extremely cold climate.The surfaces of offshore platforms operating in the Polar Regions are prone to icing.To develop solutions to this problem of surface icing,the influence of both the liquid water concentration of the surrounding atmosphere and the average water droplet diameter on the formation of ice on two major structural components of offshore platforms was analyzed using a combination of Fluent and FENSAP-ICE.Results showed that at a wind speed of 7 m/s,as the concentration of liquid water in the air increases from 0.05 to 0.25 g/m3,the amount and thickness of the icing on the surfaces of the two structural components increase linearly.At a wind speed of 7 m/s and when the size of the average water droplet diameter is 20–30(30–35)μm,as the average water droplet diameter increases,the amount and thickness of the icing on the surfaces of the two structural components increase(decrease)gradually.

Prediction Model of Aircraft Icing Based on Deep Neural Network

Icing is an important factor threatening aircraft flight safety.According to the requirements of airworthiness regulations,aircraft icing safety assessment is needed to be carried out based on the ice shapes formed under different icing conditions.Due to the complexity of the icing process,the rapid assessment of ice shape remains an important challenge.In this paper,an efficient prediction model of aircraft icing is established based on the deep belief network(DBN)and the stacked auto-encoder(SAE),which are all deep neural networks.The detailed network structures are designed and then the networks are trained according to the samples obtained by the icing numerical computation.After that the model is applied on the ice shape evaluation of NACA0012 airfoil.The results show that the model can accurately capture the nonlinear behavior of aircraft icing and thus make an excellent ice shape prediction.The model provides an important tool for aircraft icing analysis.

State of the art and practice of pavement anti-icing and de-icing techniques

Pavement snow and icing are worldwide problems, but effective countermeasures are just beginning to be developed in China. The two most common snow and ice removal methods are mechanical clearance and chemical melting, and the advantages and disadvantages of each approach are discussed here, including environmental and structural damage caused by corrosive snow melting agents. New developments in chemical melting agents and mechanical equipment are discussed, and an overview of alternative thermal melting systems is presented, including the use of geothermy and non-geothermal heating systems utilizing solar energy, electricity, conductive pavement materials, and infrared/microwave applications. Strategic recommendations are made for continued enhancement of public safety in snow and ice conditions.

Quantitative assessment of flight safety under atmospheric icing conditions

A quantitative assessment method is proposed to sense the specific effects of atmospheric icing conditions on flight safety. A six degree-of-freedom computational flight dynamics model is used to study the effects of ice accretion on aircraft dynamics, and a pilot model is also involved. In order to investigate icing severity under different icing conditions, support vector regression is applied in establishing relationship between aircraft icing parameter and weather conditions. Considering the characteristics of aircraft icing accidents, a risk probability assessment model optimized by the particle swarm method is developed to measure the safety level. In particular, angle of attack is chosen as a critical parameter in this method. Results presented in the paper for a series of simulation show that this method captures the basic effects of atmospheric icing conditions on flight safety, which may provide an important theoretical reference for icing accidents avoidance.

Investigation of Heterogeneous Ice Nucleation on the Micro-Cubic Structure Superhydrophobic Surface for Enhancing Icing-Delay Performance

The aim of this study is to explore the heterogeneous ice nucleation behavior based on controllable micro-cubic array structure surfaces from the statistic perspective.To this end,we firstly constructed a group of micro-cubic array structures on silicon substrates by a selective plasma etching technique.After grafting low-free-energy substance,the as-constructed micro-cubic array structure surfaces exhibited higher non-wettability with the water contact angle being up to 150°.On this basis,500 cycles of freezing and melting processes were accurately recorded to analyze the instantaneous ice nucleation behavior according to the statistical results of freezing temperature.As a consequence,the statistical freezing temperature of the sample with micro-spacing distance of 40μm is as low as−17.13°C.This microstructure configuration(conforming to Cassie-Baxter wetting regime)not only could entrap more air pockets,but also achieved lower solid-liquid contact area,resulting in lower ice nucleation rate(~2–3 orders of magnitude less than that on the flat substrate).Furthermore,the gradually increasing micro-spacing distance to 60μm would induce the transition from CassieBaxter to Wenzel wetting state,leading to higher freezing probability and ice nucleation rate.The complete understanding on microstructure configuration improving the ice nucleation will lay the foundation stone for the microstructure design of ice-repellent materials.

IC器件表面缺陷多光谱图像特征融合检测方法

针对IC器件表面轻微缺陷在传统的像素级融合检测中容易被产生的冗余噪声淹没,干扰缺陷特征的提取,且在光照不稳定的复杂检测场景中不能够自适应调节可见光图像与红外图像对缺陷检测任务贡献度的问题,本文提出基于多光谱图像特征融合的IC器件表面缺陷检测方法,采用中期融合策略,设计了多光谱图像特征融合模块(MIFF),在YOLO框架下建立双路特征提取通道,构建多光谱图像特征融合端对端的YOLO-MIFF缺陷检测模型。实验表明,YOLO-MIFF融合检测比单可见光和单红外图像检测的mAP分别提高了24.69%、35.65%,相比于YOLO-Multiply、YOLO-Concat、YOLO-Add模型的检测精度分别提高了9.85%、6.67%、3.44%。

Influence of liquid water content on wind turbine blade icing by numerical simulation

In order to research the influence of liquid water content ( LWC ) on blade icing of wind turbine, a numerical simulation method for blade icing was established. The numerical simulation was based on low speed viscous N-S equation. The trajectory equation of water droplets was established by Lagrangian method. The mass and energy conservation equations of the water droplets impacting on the surface of the blade were solved based on control body theory. Three sections along blade span wise of a 1.5 MW wind turbine were decided to simulate icing. Five kinds of LWC were selected for simulation including 0.2,0.4,0.6,0.8 and 1.0 g/m^3 under two ambient temperatures of -10 ℃ and -20 ℃. The medium volume droplet diameter ( MVD ) was 30μm. The simulations included icing shape on blade surface, dimensionless icing area and dimensionless maximum stagnation thickness. Furthermore, the flow fields around both the iced blade airfoil and the original one were simulated and analyzed. Accor-ding to the results, the typical icing characteristics of icing shape, icing area and thickness were greatly affected by the difference of LWCs. This study can provide theoretical reference for the research on antiicing and deicing of wind turbine blade.