Vision-based measurement systems for static and dynamic characteristics of overhead lines

In the paper, optical-based measurement methods for calculating the deflection and vibration of overhead lines are presented. The authors describe the state of the art in the field of non-contact examination of static and dynamic overhead transmission line characteristics, and propose concepts of vision-based measurement systems for both static and dynamic states of a structure. The system devoted to static measurements is based on a digital SLR camera and image-processing software used for the acquisition and interpretation of data. The digital image correlation method, implemented in Wiz2D software, is applied to compute the displacement of the transmission line cable with respect to a known baseline position. Dynamic characteristics of the structure are obtained using a stereo-vision system consisting of two high-speed digital cameras. Corresponding points in two video sequences of the vibrating cable are tracked using TEMA software. 3D positions in a camera frame of reference and displacements are computed using a 3D reconstruction method. The paper describes two series of experiments conducted on a lab setup and the obtained results are examined and discussed

Study of the influence of ice accretion on the aerodynamic coefficients of lattice tower elements

In cold regions, overhead line cables and their supporting structures are usually fully exposed to atmospheric icing. In addition, rising temperatures due to climate changes are expected to increase the risks associated with extreme weather events which in turn could possibly increase the frequency and severity of storms such as winter blizzards and ice storms. Atmospheric icing is one of the major problems in cold climate regions, which can cause serious damage to transmission line structures, such as overhead transmission networks. Towers or pylons, usually steel lattice structures, represent an important part of the cost of transmission lines. Ice deposits on exposed structures can be the source of several mechanical problems. On transmission line towers in particular, the loads due to heavy ice accretion, coupled with wind-on-ice loads, may lead to aerodynamic effects and cause structural damages, or failure and even cascading collapse of towers. The present investigation is mainly focused on the study of aerodynamic characteristics of angle member icing. The objective is to understand the influence of ice accretion on drag, lift and moment in respect to different ice profiles. In most of the previous experimental studies of ice effects on aerodynamic characteristics, aerodynamic bodies such as airfoils and wings were modeled, whereas in this research, the ice effects on bluff bodies is studied. Experimental models that explicitly consider different glaze ice profiles by including the thermo-physical properties of ice during accretion are proposed. Drag, lift and moment coefficient of those angle member reproduced using cement molded glaze ice profiles are thus measured in a wind tunnel. The models serve as a basis to study various criteria of atmospheric glaze ice effects in terms of aerodynamic coefficient and, aerodynamic forces. Various tower section geometries with glaze ice profiles can also be readily investigated using these models. Several aerodynamic scenarios of an angle member are simulated in order to investigate how variables including ice thickness, liquid water content (LWC), droplet size distribution (DSD) and Reynolds number affect the drag, lift and moment coefficients of an iced angle member subjected to air velocity. Ice morphology of an angle member for different aerodynamic angles and different model orientations are also explored in order to study the flow characteristics effects on ice accretion. Dans les régions froides, les câbles des lignes de transport et leurs structures sont généralement exposés au givrage atmosphérique. En outre, l'élévation des températures en raison des changements climatiques devraient accroître les risques associés aux phénomènes météorologiques extrêmes, qui à leur tour pourraient éventuellement augmenter la fréquence et la gravité des tempêtes telles que les tempêtes de neige hivernales et les tempêtes de verglas. Dans les régions au climat froid, le givrage atmosphérique est un des problèmes majeurs qui peut causer de graves dommages aux structures des lignes aériennes de transport de l’énergie électrique. Les pylônes, dont les structures sont normalement composées de treillis métalliques, représentent une part importante du coût des lignes de transport. Les dépôts de glace sur les structures exposées peuvent être la source de plusieurs problèmes mécaniques. Plus spécifiquement sur les pylônes des lignes électriques, les charges occasionnées par une épaisse couche de glace, couplées avec celles créées par le vent, peuvent entraîner des charges aérodynamiques excessives et causer des dommages structuraux, des bris ou même un effondrement en cascade des pylônes. Cette recherche a principalement porté sur l'étude des caractéristiques aérodynamiques des cornières sous l'effet du givrage. L'objectif était de comprendre l'influence de différents profils de glace sur la traînée, la portance et le moment aérodynamique. Dans la plupart des études expérimentales précédentes sur les effets de la glace sur les caractéristiques aérodynamiques, des corps profilés tels des ailes d’avion ont été modélisés alors que dans cette recherche, ce sont les effets de la glace sur des corps non profilés qui ont été étudiés. Des modèles expérimentaux tenant explicitement compte de différents profils de glace, tout en incluant les propriétés thermo-physiques de la glace durant l'accrétion, ont été proposés. Les coefficients de traînée, de portance et le moment des profils de glace reproduits à l’aide de ciment moulé sur une cornière ont été mesurés en soufflerie. Les modèles développés peuvent servir de base pour l’étude des effets de la glace atmosphérique, tels les coefficients aérodynamiques et les forces aérodynamiques. Différentes géométries de section de pylônes avec des profils de glace peuvent également être plus facilement étudiées à l'aide de ces modèles. Plusieurs scénarios aérodynamiques sont simulés afin d'étudier comment des variables, tels que l’épaisseur de la glace, la teneur en eau liquide, la taille des gouttelettes et le nombre de Reynolds, affectent les coefficients de traînée, la portance et le moment d'une cornière givrée soumise à un écoulement d'air. La morphologie de la glace accumulée sur une cornière, pour différents angles d’attaque aérodynamiques et différentes orientations de la cornière, est également explorée afin d'étudier l’effet des paramètres du vent sur une accrétion de glace

Image analysis methods in the measurement of ice loads on structures

The icing of marine vessels and offshore structures causes significant reductions in their efficiency and creates unsafe working conditions. Ice detection and removal play important roles to reduce the risk of hazards and increase operational efficiency. Ice detection and measurement on structures are a challenge in marine industries, due to a lack of studies in this field. In this research, image processing methods are developed to measure ice loads on structures. Image processing algorithms are used to detect the ice accumulated on the structures and then the ice loads are calculated. The combination of thermal and visual imaging is suggested to detect ice, in order to reduce drawbacks occurring in these types of imaging. Also, the ice load is calculated on a known structure based on the structure information and the ice detection results. Experiments are conducted to verify the results of ice load measurements obtained by the algorithms. Ice loads are calculated in a variety of situations, such as using different imaging types, changing camera positions and angles of view and using different ice load values. The calculated ice load results show good coherence with the actual values obtained by measuring the samples which are used in the experimental setups

NASA-ASEE Summer Faculty Fellowship Program at NASA Lewis Research Center

During the summer of 1996, a ten-week Summer Faculty Fellowship Program was conducted at the NASA Lewis Research Center (LeRC) in collaboration with Case Western Reserve University (CWRU), and the Ohio Aerospace Institute (OAI). This is the thirty-third summer of this program at Lewis. It was one of nine summer programs sponsored by NASA in 1996, at various field centers under the auspices of the American Society for Engineering Education (ASEE). The objectives of the program are: (1) to further the professional knowledge of qualified engineering and science educators, (2) to stimulate an exchange of ideas between participants and NASA, (3) to enrich and refresh the research activities of participants' institutions. (4) to contribute to the research objectives of LeRC. This report is intended to recapitulate the activities comprising the 1996 Lewis Summer Faculty Fellowship Program, to summarize evaluations by the participants, and to make recommendations regarding future programs

Experimental investigations on the characteristics of snow accretion using the EMU-320 model train

This paper presents a snow accretion test conducted in a climate wind tunnel to investigate the icing process on a model train. The model used within this experiment was the cleaned-up and 2/3-scaled version of EMU-320, which is a high-speed train in Korea. The model was designed without an electronic power source or heat source so that the wheels did not rotate and snow accretion on the model did not occur due to heat sources. To investigate snow accretion, four cases with different ambient temperatures were considered in the climate wind tunnel on Rail Tec Arsenal. Before analyzing the snow accretion on the train, the snow flux and liquid water content of snow were measured so that they could be used as the input conditions for the simulation and to ensure the analysis of the icing process was based on the characteristics of the snow. Both qualitative and quantitative data were obtained, whereby photographs was used for qualitative analysis, and the density of the snow sample and the thickness of snow accreted on the model were used for quantitative analysis. Based on the visual observations, it was deduced that as the ambient temperature increased, the range of the snow accreted was broader. The thickness of snow accreted on the model nose was the largest on the upper and lower part at -3 oC, and on the middle part at -5 oC. Additionally, the cross section of snow accreted was observed to be trench-like. Similar icing processes were observed to occur on the slope of nose. Snow accreted on all components of the bogie, and for all cases, the thickness of snow at wheel was the largest at an arc angle of 40 to 70 o. These detailed data of experimental conditions can be applied as an input to simulations to improve simulations of ice conditions. Thus, they can facilitate the development of appropriate anti-icing designs for trainsComment: 31 pages, 23 Figures, 8 Table

Deep Mapping of Small Solar System Bodies with Galactic Cosmic Ray Secondary Particle Showers

We will investigate the use of galactic cosmic ray (GCR) secondary particles to probe the deep interiors of small solar system bodies (SSBs), including comets, asteroids, and geologic structures on the surfaces of airless bodies. Applications include solar system science, planetary defense, and resource utilization. Our Phase I study demonstrated that muons, the long-range charged component of GCR showers, can penetrate SSBs up to a km in diameter, providing information on their interior structure. Muons produced in Earths atmosphere have been applied to image the interior of large objects for science and engineering. In Phase I, we found that the production of muons in the solid surfaces of airless bodies is much smaller than in Earths atmosphere. Nevertheless, the flux of transmitted muons is sufficient to detect inclusions within an asteroid or comet in a reasonable amount of time, ranging from hours to weeks, depending on the size of the SSB and the density contrast, position and size of the inclusion. For asteroids and comets, large density variations (e.g., porous soil or ice versus solid rock) are relatively easy to detect. The intrinsic spatial resolution of muon radiography (muography) is on the scale of a few meters. The spatial resolution that can be achieved in practice depends on signal intensity and integration time (counting statistics), the angular resolution of the muon tracker (hodoscope) and details of data reduction and analysis methodology. Our Phase II project will assess remaining unknowns for the application of muography to determining the interior structure of SSBs, assess risks for implementation, and provide a roadmap for development of SSB muography beyond the NIAC program. To achieve our objectives, we will focus on four interrelated tasks: Task1) Signal and background characterization: Characterize the production and transmission of muons and secondary particle backgrounds made by cosmic ray showers in SSBs; and near-surface features from radiographic and tomographic data; Task2) Imaging studies: Develop methods to determine the density structure of SSB interiors and near-surface features from radiographic and tomographic data; Task3) Instrument design: Using simulations and bench-top laboratory experiments, investigate specific concepts for the design of compact hodoscopes and components; Task4) Synthesis: Combine the results of the first three tasks to determine the range of applicability of the method, identify the steps needed for maturation of the concept, and explore concepts for a pilot muography mission

Icing Effects on Power Lines and Anti-icing and De-icing Methods

Icing on power lines may lead to compromise safety and reliability of electric supply network. Prolong icing can lead to power breakdown and collapse of towers. Since power transmission lines are mostly overhead and could face the direct impact of icing, and it is one of the main challenges faced by power distribution companies in cold regions. When the ice accretion crosses the safety limit then deicing action can be carried out. We can find number of deicing methods that are used in different parts of the world. However, all of these deicing techniques have their own advantages and disadvantages on implementation. It is one of the most difficult as well as dangerous process to perform deicing on power lines. If a fault is detected and that has been occurred due to icing or during routine maintenance, extra care must be taken in order to ensure safety of the personals when performing de-icing of lines. However, as technology evolved, new ways and techniques are adopted with the help of sensors that give quick feedback to control room in the national grid via wireless communication network for real time action. In the thesis we have discussed atmospheric icing impacts on power lines in the cold regions across the world. A literature review has been done for anti-icing and deicing methods that are currently adopted in the power distribution network. Methods that are used against ice buildups have also been analyzed. This work also shows the impacts of icing and deicing techniques presently adopted, and also throws light on their pros and cons during maintenance operations. It provides an overview of the evolving technology trends that are practiced to ensure the availability of existing power transmission system in cold climate regions

Development of a Mode I test rig for quantitative measurements of ice adhesion using tensile stress

Every winter in Canada, ice formation affects airplanes, power lines, telecommunications equipment, windmills, ships and rail transport. Icing in aeronautics augment significant human and monetary costs. From the National Transportation Safety Board (NTSB) Accident Database, during a 19-year period 583 accidents and more than 800 fatalities were caused by airframe icing accidents. Ice accumulation on aerostructures causes a variety of issues — loss of lift, increase in drag, jamming of control surfaces or of mechanical parts, damage of engine blades. Thus, aircraft icing affects the safety of flight and increases fuel consumption. Engineers have developed various techniques for anti-\ and de-icing areas for components of an aircraft that are affected. In laboratory settings, these technologies show promising results. However, they are designed and tested under ‘‘ideal’’ conditions and consequently they often underperform in practical applications. Not all of the technologies make it beyond the conceptual phase, which is also due to the fact that the processes of ice accretion and ice adhesion are not fully understood yet. The purpose of this thesis is to study the available ice adhesion tests in order to select and develop an easy to use and reproducible testing tool for measuring ice adhesion. The Mode I or tensile was chosen because the analysis of the results is well understood, the test is fully controlled and it can be easily reproduced. Test results will simulate real, in-flight icing conditions. Mode I applies tensile loading at the ice-substrate interface. The CRT icing wind tunnel has the capability of investigating the ice adhesion with a bending cantilever test that measures the ice-substrate interfacial strength based on harmonic excitation with a permanent magnet shaker. This proposed study will help researchers and engineers to develop reliable systems by correlating the complementary ice adhesion results obtained from the Mode I and the bending cantilever tests. The intention is to minimize the risk of failures when conducting full-scale or flight testing. The prevention of ice build-up on aircraft structures or its easy removal will reduce safety hazards, in addition to leading to considerable savings, both financial and environmental. Further advancement in the technology of ice protection systems will contribute to retaining Canada’s position as the leading authority of aerospace, green energy production, and consumer products

Aeronautical engineering: A continuing bibliography with indexes (supplement 282)

This bibliography lists 623 reports, articles, and other documents introduced into the NASA scientific and technical information system in Aug. 1992. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles