Electric power transmission and maintenance is essential for the power industry. This paper proposes a method for the efficient extraction and classification of three-dimensional (3D) targets of ...electric power transmission facilities based on regularized grid characteristics computed from point cloud data acquired by unmanned aerial vehicles (UAVs). First, a spatial hashing matrix was constructed to store the point cloud after noise removal by a statistical method, which calculated the local distribution characteristics of the points within each sparse grid. Secondly, power lines were extracted by neighboring grids’ height similarity estimation and linear feature clustering. Thirdly, by analyzing features of the grid in the horizontal and vertical directions, the transmission towers in candidate tower areas were identified. The pylon center was then determined by a vertical slicing analysis. Finally, optimization was carried out, considering the topological relationship between the line segments and pylons to refine the extraction. Experimental results showed that the proposed method was able to efficiently obtain accurate coordinates of pylon and attachments in the massive point data and to produce a reliable segmentation with an overall precision of 97%. The optimized algorithm was capable of eliminating interference from isolated tall trees and communication signal poles. The 3D geo-information of high-voltage (HV) power lines, pylons, conductors thus extracted, and of further reconstructed 3D models can provide valuable foundations for UAV remote-sensing inspection and corridor safety maintenance.
Salah satu kemampuan dasar wahana terbang type fixedwing adalah dapat lepas landas pada area yang terbatas, terbang cepat mencapai lokasi yang diinginkan secara aman, akurat pada lintasan yang ...diinginkan dan dapat kembali ke base untuk mendarat dengan selamat. Misi khusus seperti pertolongan dan pertahanan membutuhkan wahana terbang yang cepat dan mampu mendarat dengan akurat, tetapi performa tersebut juga membutuhkan konsumsi energi yang besar. Untuk mendapatkan performa yang cepat, namun dengan energi yang efisien, wahana terbang didesain dengan model pylon pusher menggunakan airfoil ag03-il dan penambahan stabilizer cruciform untuk meningkatkan kecepatan pesawat dan menjaga pesawat agar stabil. Untuk tahap awal penelitian ini dibagi menjadi tiga proses yaitu menentukan konfigurasi pesawat, membuat gambar tiga dimensi, dan menganalisis desain tiga dimensi menggunakan software ansys. Hasil ketiga proses tersebut didapatkan desain baru dengan konfigurasi penempatan sayap (hight wing) dengan ekor menggunakan stabilizer cruciform. Data teknis hasil perancangan adalah sebagai berikut: berat take-off 23 N, luas sayap 0,378 dan panjang pesawat 0,72 m pada saat kecepatan jelajah koefisien gaya angkat (Cl) 0,35 dan koefisien gaya angkat maksimum (CLmax) pesawat sebesar 1,12 ketika sudut serang .selain itu diperlukan campur tangan pilot melalui remote control untuk menghasilkan kecepatan yang maksimal. Desain baru pesawat model fighter untuk divisi Racing Plane mampu menambah kecepatan hingga 30% dari yang telah dibuat model pylon.
The current study numerically investigates the effect of fuel injection locations within a pylon-cavity aided Supersonic Combustion Ramjet (SCRAMJET) combustor on mixing enhancement, flame holding, ...fuel jet penetration and total pressure loss. RANS equations for compressed real gas are solved by coupled, implicit, second-order upwind solver. Two-equation SST model is used for turbulence modelling. The computational model is validated using experimental steady wall pressure data and 2D velocity field. The study uses seven distinct sonic fuel injection location cases of hydrogen fuel through a 1 mm diameter hole along the axis of the test section floor. All cases maintain crossflow of Mach number 2.2. The simulations show that the counter rotating vortex pair within the cavity plays a vital role in fuel dispersion and fuel jet penetration capability. The presence of pylon resulted in an increase of pressure loss by 7%, whereas the influence on total pressure loss due to transverse fuel injection is found to be insignificant. The injection locations within the cavity give around 55% (max) increase in fuel dispersion compared to location upstream of the pylon. Also the cavity floor locations give about 55% - 90% more flammable plume area than the injection from other locations.
There have been significant advancements in artificial limbs called prosthetics. People with leg amputations may find it easier to move around with the aid of prosthetic legs or prosthesis. An ...artificial device known as a prosthesis or prosthetic implant replaces a missing bodily component that may have been lost due to trauma, illness, or a birth defect (congenital disorder). Prostheses are designed to replace the missing body part's lost functionality. They imitate the way a leg works and occasionally even how it looks. While some prosthetic limb users still use a cane, walker, or crutches to walk, others can do it without any assistance. To permit an amputee and to rehabilitate to a healthy locomotion its intended to develop an economical pylon prosthetics using CAD and FEA software. Nine combinations of three metal Titanium, Stainless steel and Aluminium for prosthetics specimen are developed using manual measurement and 3-D measurement. For each nine combinations the stress, strain, analysis is conducted and compared among the combinations to get an optimized model of metal combination with a maximum stress of 1.643e + 07 N/m2 which is near to the maximum stress of existing model 2.023e + 07 N/m2. This re-developed model is compared with the existing model to produce an optimized model that could meet the requirements of an amputee.
Mixing of ethylene secondary jet injected behind a curved pylon in supersonic cross-flow at a Mach number of 1.65 has been studied numerically with experimental validation. For the validation of ...numerical results, Schlieren, wall pressure measurements, particle image velocimetry, and planar laser-induced fluorescence experiments were performed. Ethylene fuel was used for the simulation, and air was used as a substitute fuel in the experiments. In this study, the curved pylon with different curvatures has been studied at 3.5 bar and 7 bar secondary injection pressures. The results are compared with the standard pylon and conventional transverse injection cases. The results showed improvements in mixing parameters when curved pylons were used. Results indicated that complete mixing was achieved in pylon cases at a much shorter distance than in the transverse injection. The complete mixing distance for the pylon cases was observed around z/dj = 50 and z/dj = 80 for 3.5 bar and 7 bar injection cases, respectively. Even though the mixing efficiencies were similar for all the pylon cases, the flammable plume area and total pressure loss differed. Changes in the bottom curvature angle at the trailing edge of the pylon caused different streamwise vortex structures, which affected the flammable plume area. A considerable difference was found in the penetration height among pylons at 3.5 bar injection pressure, and the difference became minimal at 7 bar injection pressure. Penetration height was greatly affected by the interaction of the secondary jet with the low-pressure region and the momentum flux ratio of the secondary jet. At least a 1 % reduction in total pressure loss was found for curved pylon cases when compared with the standard pylon.
•Short complete mixing lengths using pylons.•Curved pylons produce better flammable plume area and lower total pressure loss.•Different curvatures produce different vortex structures.•Penetration height is greatly affected by the wake interaction.
•Tensile stiffness of PBLs in composite pylons is experimentally and numerically studied.•Perforated rib’s geometric properties significantly affect tensile stiffness of PBLs.•Increasing concrete ...strength increases tensile stiffness of PBLs.•Proposed analytical spring model accurately predicts tensile stiffness of PBLs.
Perfobond rib connectors (PBLs) are subjected to considerable tensile forces when used as stiffeners in steel panels and force-transfer structures in the cable anchorage zone in the steel–concrete composite pylons of cable-stayed bridges. Determining the elastic tensile stiffness of the PBLs is necessary for a structural analysis of the composite pylons. This investigation aimed to explore the critical parameters affecting the elastic tensile stiffness of PBLs and propose equations for accurately predicting the tensile stiffness of PBLs. Twelve PBL specimens were tested under pull-out load to investigate their elastic tensile stiffness. Thereafter, a parametric analysis was conducted via the finite element approach to examine the influence of the geometric characteristics of the perforated rib, transverse rebar diameter, and concrete strength on the tensile stiffness of the PBL. The results demonstrated that the elastic tensile stiffness of PBLs increased with the increase in the rib thickness, hole diameter, and concrete strength but decreased with increasing embedded depth. The perforated rib width had no influence on the elastic tensile stiffness. Additionally, the elastic tensile stiffness increased slightly as the transverse rebar diameter increased. Subsequently, a theoretical spring model was developed to predict the elastic tensile stiffness of the PBLs, considering the contribution of perforated ribs and concrete dowels. Finally, a comparative analysis was performed, which proved that the proposed equations in the present study based on the spring model were accurate in predicting the tensile stiffness of PBLs. The proposed equations are recommended for application in the structural analysis of composite pylons.
The reconstruction of 3-D models of power pylons from light detection and ranging (LiDAR) data plays an important role in power transmission safety. However, accurate reconstruction of power pylon ...models still faces challenges, e.g., complex structures, missing data, and occlusion. In this letter, a novel four-component segmentation method is proposed for reconstructing power pylon models. In the proposed method, the pylon components of the pylon head, pylon body, cross-arms, and pedestal are first defined in terms of the common features and functionality of each component. Then, these four components are each segmented and identified based on their position and shape features from the raw point cloud. An improved approach based on Metropolis-Hastings sampling and a simulated annealing algorithm is proposed to estimate the model parameters. Based on the estimated parameters, the 3-D shapes of the individual components are reconstructed and stacked to form the whole pylon model. Experimental results show that our methods are able to reconstruct pylons with complex-shaped heads and multiple cross-arms, with an average reconstruction error of less than 0.3 m. Compared with the standard Metropolis-Hastings algorithm with annealing, the parameter estimation process in our strategy improves the computational efficiency by 7.54%.
Pylons play an important role in the safe operation of power transmission grids. Directly reconstructing pylons from UAV images is still a great challenge due to problems of weak texture, ...hollow-carved structure, and self-occlusion. This paper presents an automatic model-driven method for pylon reconstruction from oblique UAV images. The pylons are reconstructed with the aid of the 3D parametric model library, which is represented by connected key points based on symmetry and coplanarity. First, an efficient pylon detection method is applied to detect the pylons in the proposed region, which are obtained by clustering the line segment intersection points. Second, the pylon model library is designed to assist in pylon reconstruction. In the predefined pylon model library, a pylon is divided into two parts: pylon body and pylon head. Before pylon reconstruction, the pylon type is identified by the inner distance shape context (IDSC) algorithm, which matches the shape contours of pylon extracted from UAV images and the projected pylon model. With the a priori shape and coplanar constraint, the line segments on pylon body are matched and the pylon body is modeled by fitting four principle legs and four side planes. Then a Markov Chain Monte Carlo (MCMC) sampler is used to estimate the parameters of the pylon head by computing the maximum probability between the projected model and the extracted line segments in images. Experimental results on several UAV image datasets show that the proposed method is a feasible way of automatically reconstructing the pylon.
•The cable as a down-lead for a composite pylon is studied by simulation. The dynamic capacitance of the corona emanating from the dielectric has been obtained by experiments.•The effects of the ...corona on the cable down-lead on the overvoltage and lightning performance have been analyzed.•The phase voltage effect on the pylon critical current has been explored.
This paper investigates the effect of the impulse corona inside the cross-arm on the lightning performance of a Y-shaped composite pylon with a cable as an internal down-lead through the hollow cross-arm. First, the electromagnetic transient model for the down-lead system of the composite pylon is built. The simplified steps for calculating the surge impedance of the cable down-lead are given. In addition, the mutual coupling between two down-leads is considered. Through a laboratory test on coaxial cylinders resembling the structure of the cable and cross-arm, the dynamic capacitance of the corona on the surface of the cable is obtained and included in the electromagnetic transient model. Then, the effect of the corona on the traveling waveform and mutual capacitance is discussed. Furthermore, the influences of the ground electrode length and the phase voltage on lightning performance are also studied. Finally, the backflash rates of the composite pylon with cable as down-lead are calculated. The results show that the impulse corona has a limited impact on the critical current, and the composite pylon with cable as down-lead shows a promising lightning performance.
The down-lead system allows the direct strokes to be conducted efficiently to the ground and plays a vital role in the lightning protection of transmission towers. In this paper, the feasibility of a ...cable as a down-lead for a 400 kV composite pylon with the ‘Y’ pattern is investigated from the perspectives of the electrical insulation and lightning performance. A 3D full-size model is built in COMSOL to study the electric field distribution inside of the pylon cross-arm. Meanwhile, two coaxial Fiber Reinforced Plastic tubes are used to resemble the structure of a cable passing through a hollow cross-arm. The corona inception electric field on the surface of the cable with different radii under AC 50 Hz applied voltage and the corona characteristics under switching overvoltage are analyzed. Based on experimental tests, the cable parameters are determined. Then, an electromagnetic transient model for the pylon down-lead system considering impulse corona effect has been built in PSCAD/EMTDC and the backflashover rate is obtained. Finally, the cable insulation strength under the transient overvoltage is validated by lightning test. The research shows that a cable with appropriate dimensions used as a down-lead can meet electrical insulation requirements and presents a good lightning performance.
•The cable as a down-lead for a composite pylon is studied by simulation and experiments.•The relationship between corona power on cable surface and applied electric field intensity is obtained by experiments.•The Electromagnetic Transient model of the down-lead system is simulated to investigate the lightning performance of the pylon as well as the internal overvoltage of the cable.•Combined with the dielectric breakdown strength test and finite element simulation, the insulation strength of the cable is verified.
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