Metallic Tower Research Articles

Growing Stress-Strain State of a Metal Tower Structure Intended for Placing Cellular Communication Equipment in the Presence of Corrosion Damages of Individual Elements and Connections of its Support

Statement of the problem. The article presents the results of a study of the stress-strain state of a me-tal tower, to accommodate cellular communication equipment, in the presence of corrosion damage to individual elements and connections of the support. The effect of section reduction on the change in horizontal displacements of the structure, as well as on the bearing capacity of individual rods, is considered. The relationship between the decrease in the thickness of the considered section and the above parameters is described. Results. The absence of a linear relationship between the increase in corrosion damage and the change in horizontal displacements of the upper support points was established. An approach to assessing corrosion wear is proposed, using a regression function that takes into account corrosion intensity and rate factors. Conclusions. The phenomenon under consideration leads to an increase in sign-variable movements and causes a negative impact on process equipment with a deviation of 0o18', exceeding the allowable value of trouble-free operation by 1.5 times.

Modelling and performance investigation of a solar chimney power plant with glass-covered solar collector

ABSTRACT Solar chimney power plants (SCPP) exploit solar radiation to create an up-draft airflow to run a turbine. This article proposes an innovative design of an SCPP that consists of transparent glass covered solar collector. Outdoor experiments have been carried out in the arid climates of Tikrit city, Iraq, with galvanized metal tower installed instead of conventional PVC solar towers. Performance of the SCPP has been studied with and without transparent cover for collector periphery heights of 2 and 4 cm. Measurements of ambient temperature, chimney inlet temperature, interior and outlet air temperatures, humidity, air mass flow rate, and solar irradiance values were recorded from 9:00 am to 4:00 pm throughout the month of May 2021. Results show that the solar chimney collector with a periphery height of 2 cm performed better than that with the 4-cm periphery height. In addition, using transparent cover in SCPP increases the air outlet temperature by 16.4°C and air flowrate augments by around 34%. Thermal efficiency of the solar chimney with non-covered tower is found to be 10.3% whereas for a glass covered tower it increases to 14.6%, which is a remarkable 41% enhancement. Likewise, mechanical and electrical power output augment by 39.6% and 40.3% using transparent cover in SCPP. Such innovation in SCPP design is proven apposite for hot arid climates.

Design and application of a UHF RFID tag for monitoring pollution in high voltage towers

Pollution diagnosis is difficult and costly for power grid operators. For the purpose of have an effective, low-cost and user-friendly pollution diagnosis, a Radio Frequency Identification prototype is proposed - an RFID tag for identifying and monitoring pollution in high voltage towers. For that, the following steps were performed: dielectric characterization of artificial pollution; project via simulation of RFID tags for application in metallic towers; manufacture, validation and testing of tags; sensitivity analysis of tag reach; and computational algorithm for signal treatment and subsequent identification. Pollution identification was based on variations of the Received Signal Intensity Indicator (RSSI) by the reader as a function of the amount of pollution deposited. The validation and testing of the tags were carried out in an external environment with an emulation of a de-energized high voltage tower. For all levels of deposited pollution analyzed, the average maximum reach of the signal reading, in an external environment, was 18 m. The RSSI data, obtained by reading the RFID tag, were processed and analyzed to identify the pollution deposited on the high voltage transmission towers. The results demonstrated the potential of the tags for identification and monitoring pollution levels in high voltage metal towers.

Fair-Weather Atmospheric Charge Measurements with a Small UAS

Abstract Atmospheric electricity measurements made from small unmanned aircraft systems (UAS) are rare but are of increasing interest to the atmospheric science community due to the information that they can provide about aerosol and turbulence characteristics of the atmospheric boundary layer (ABL). Here we present the first analysis of a new dataset of space charge and meteorology measurements made from the small, electric, fixed-wing UAS model MASC-3. Two distinct experiments are discussed: 1) Flights past a 99 m metal tower to test the response of the charge sensor to a fixed distortion of the electric field caused by the geometry of the tower. Excellent agreement is found between the charge sensor response from the MASC-3 and modeled electric field around the tower. 2) Vertical profiles up to an altitude of 2500 m to study the evolution of the ABL with the time of day. These flights demonstrated close agreement between the space charge profiles and temperature, relative humidity, and turbulence parameters, as would be expected on a fair-weather day with summertime convection. Maximum values of space charge measured were of order 70 pC m−3, comparable with other measurements in the literature from balloon platforms. These measurements demonstrate the suitability of small UAS for atmospheric electrical measurements, provided that care is taken over the choice of aircraft platform, sensor placement, minimization of electrical interference, and careful choice of the flight path. Such aircraft are typically more cost-effective than manned aircraft and are being increasingly used for atmospheric science purposes.

Effect of Different Bracing Systems on the Performance of Metallic Tower

Effect of Different Bracing Systems on the Performance of Metallic Tower

Vibration damping of a vertical axis wind turbine in operating conditions

Distributed power generation technologies have been, over the years, gaining more and more attention from the industry as well as from the academia, due to the global interest in the exploitation of renewable energy sources even in urban areas. From this perspective, small size wind turbines, often with vertical axis layout and a nominal power between 1-3 kW, are being installed in urban areas on rooftops of residential, commercial, industrial buildings and even on metallic carpentry towers. As wind turbines tend to produce noise and vibrations, especially in presence of vortexes, wakes and unsteadiness, efficient devices for mitigating the vibrations transmitted to the supporting structure have to be added in order to limit the generation of stresses. Actually, the social acceptance of the installation of small wind turbines in built environment is tightly connected to the acoustic comfort for the inhabitants. The present study has been developed thanks to a joint collaboration between the Department of Engineering of the University of Perugia (Italy) and FH Technikum Wien (Austria) within the participation to the IEA Wind-Task 41: “Distributed Wind”. The work aims at mechanically characterizing the vibration damping provided by a mechanical device installed on the top of the turbine tower support. The decoupler, specifically designed for this purpose, has been tested in different conditions (in field and laboratory) and with different approaches, in order to have an overall evaluation of its performance. At first, vibrations are measured in open field in a real test case scenario with two installation arrangements: on the rooftop of a small building and on a tubular tower. Subsequently, the decoupler has been removed from its original location and tested in laboratory with external excitation from shaker.

Vertical stratification of insect abundance and species richness in an Amazonian tropical forest

Tropical forests are among the most biodiverse biomes on the planet. Nevertheless, quantifying the abundance and species richness within megadiverse groups is a significant challenge. We designed a study to address this challenge by documenting the variability of the insect fauna across a vertical canopy gradient in a Central Amazonian tropical forest. Insects were sampled over two weeks using 6-m Gressitt-style Malaise traps set at five heights (0 m–32 m–8 m intervals) on a metal tower in a tropical forest north of Manaus, Brazil. The traps contained 37,778 specimens of 18 orders of insects. Using simulation approaches and nonparametric analyses, we interpreted the abundance and richness of insects along this gradient. Diptera, Hymenoptera, and Coleoptera had their greatest abundance at the ground level, whereas Lepidoptera and Hemiptera were more abundant in the upper levels of the canopy. We identified species of 38 of the 56 families of Diptera, finding that 527 out of 856 species (61.6%) were not sampled at the ground level. Mycetophilidae, Tipulidae, and Phoridae were significantly more diverse and/or abundant at the ground level, while Tachinidae, Dolichopodidae, and Lauxaniidae were more diverse or abundant at upper levels. Our study suggests the need for a careful discussion of strategies of tropical forest conservation based on a much more complete understanding of the three-dimensional distribution of its insect diversity.

Estimation of the Tower Shape Effect on the Stress–Strain Behavior of Wind Turbines Operating under Offshore Boundary Conditions

The metal tower, or the pylon, is one of the most important elements in the construction of a wind turbine. It has the role of supporting the entire wind turbine, and it also allows access for inspection and conducting planned maintenance and repairs. Moreover, the tower ensures support for the structure and strengthens the whole assembly. It has a particularly important role, as it has to face very severe weather conditions. The present study aims to analyze the forces and moments resulting from the action of the wind on the tower of a wind turbine. Two important load cases are considered, namely, the load under operating conditions and the ultimate load under 50 year wind conditions. For this purpose, cylindrical and conical geometric shapes of the tower were chosen. These were analyzed under the action of both normal and extreme wind speeds. Then, the behavior of the two towers under the action of the wind speed for a location in the Black Sea was analyzed. Finally, in an attempt to make the structure more economical, the thickness of the shell was reduced.

Research on Construction and Sizing of the Metal Structure of a Winding Installation

The paper focuses on the design of the metal tower for the sinking of Netiș de-ventilating shaft in Râul Mare Retezat hydro-energetic setup. The analytical calculation of sizing and verification of the metal structure is doubled by the graphic simulation with speciality software, in view of obtaining results as close as possible to the real exploitation conditions of the tower. The tower of the de-ventilating shaft is considered to be a temporary construction, and its component parts will be decommissioned once the sinking is finalized. The tower is made up of metal structures in four transoms, 3 being mounted with junction plates and screws, the fourth being the roof.

Comparison of Backflashover performance between a novel composite pylon and metallic towers

A design of a fully composite pylon with external grounding down-leads has been proposed for new-generation 400 kV transmission towers, able to save lines corridors and to reduce visual impact. This paper investigates and compares the backflashover performance of a composite pylon and two conventional metallic towers, which have been widely installed in Denmark. The transient models of overhead lines and all three towers were established respectively and the transient analysis was carried out in PSCAD. Monte Carlo method was used to estimate backflashover rate. The backflashover rate of composite pylon is 0.4526 cases per 100 km per year, which is in the same range, but slightly higher than that of metallic towers. The separated grounding down-leads of double circuits on composite pylon eliminates the danger of simultaneous backflashover of double circuits, which exists in transmission lines supported by metallic towers. After comparing the overvoltages to three phases of the three towers from backflashover, it is worthy considering that the installation of surge arresters at all three phases of composite pylon has a strong impact on the backflashover rather, but for the two metallic towers only the surge arresters at the upper phase has an impact.

On the Spectral and Polarimetric Signatures of a Bright Scatterer before and after Hardware Replacement

A previous study has used the stable and peculiar echoes backscattered by a single “bright scatterer” (BS) during five winter days to characterize the hardware of C-band, the dual-polarization radar located at Monte Lema (1625 m altitude) in Southern Switzerland. The BS is the 90 m tall metallic tower on Cimetta (1633 m altitude, 18 km range). In this note, the statistics of the echoes from the BS were derived from other ten dry days with normal propagation conditions in winter 2015 and January 2019. The study confirms that spectral signatures, such as spectrum width, wideband noise and Doppler velocity, were persistently stable. Regarding the polarimetric signatures, the large values (with small dispersion) of the copolar correlation coefficient between horizontal and vertical polarization were also confirmed: the average value was 0.9961 (0.9982) in winter 2015 (January 2019); the daily standard deviations were very small, ranging from 0.0007 to 0.0030. The dispersion of the differential phase shift was also confirmed to be quite small: the daily standard deviation ranged from a minimum of 2.5° to a maximum of 5.3°. Radar reflectivities in both polarizations were typically around 80 dBz and were confirmed to be among the largest values observed in the surveillance volume of the Monte Lema radar. Finally, another recent 5-day data set from January 2020 was analyzed after the replacement of the radar calibration unit that includes low noise amplifiers: these five days show poorer characteristics of the polarimetric signatures and a few outliers affecting the spectral signatures. It was shown that the “historical” polarimetric and spectral signatures of a bright scatterer could represent a benchmark for an in-depth comparison after hardware replacements.

КОМПОЗИТНІ ОПОРИ ПОВІТРЯНИХ ЛІНІЙ ЕЛЕКТРОПЕРЕДАЧІ

The article considers the feasibility of using composite supports during the replacement of overhead power lines, analyzes the relevance of these technologies. The advantages of composite overhead power line towers for construction, modernization and restoration work over traditional wooden and metal towers are substantiated.

Seasonal and interannual variability of CO2 above the moist tropical forest of southern Vietnam

The paper presents the results of a study of seasonal and interannual variability of CO2 concentration above the moist tropical forest in southern Vietnam. Experimental data were collected during year-long observation of CO2 directly in the forest from 2012 to 2017. All data were obtained through the use of an air intake tube, placed on a metal tower at a height of 46 m and connected to a Li-Cor 820 gas analyzer (Li-Cor Inc., USA) located in a building at the foot of the tower. The values of the concentration were recorded with a resolution of 1 second; for further analysis, all data was averaged to 0.5 h values. Statistical processing based on the Fourier analysis allowed to evaluate the main characteristics of the annual distribution of CO2 concentration, such as the amplitude and phase, as well as to analyze their variability over the years. The results of the study showed a presence of a well-determined annual course of CO2 concentration above the canopy of the moist tropical forest.

Study of the state of atmospheric air in the vicinity of non-ferrous metallurgy facilities and the power line tower damage

In the studies of the state of land areas performed using the advanced methods, in images from space, the industrial region around the city of Norilsk can be seen as a blurred spot that occupies an area of more than 900 km2. Among diverse pollutants forming the picture, sulfur and nitrogen compounds, nitrates, sulfates, phenols, industrial dust, and heavy metals have a particular impact. The release of sour gases results in acid rains, which are among the major pollutants forming the whole picture. These substances affect humans, all objects of the environment, and sources of anthropogenic activities including engineering installations of power plant enterprises. The direct impact on the state of metal towers decreases significantly their lifetimes and increases the risk of emergencies. In this paper, the research data on the state of power line towers of different types are provided and the effect of acid precipitation on structures is shown.

Characterization and Optimization of a Collinear Array of Circularly Polarized Side-Mounted Elements

This paper presents the radiation characteristics of a two-element collinear array of shunt-fed, slanted dipoles side-mounted to a metallic tower. It presents the radiation characteristics of the array as commonly implemented by FM broadcasters and suggests methods on how to optimize these characteristics such as the power gain, pattern circularity, side-lobe reduction, and horizontal-vertical polarization component ratio for the array to better conform to broadcast standards. By determining these characteristics using an advance antenna simulation software, optimization variables are identified, and their optimized values are determined. The optimized values lead to improved radiation characteristics of the array in conforming with broadcast requirements. Results show that adjusting the distance between the dipoles to less than one wavelength reduces the sidelobe of the array radiation pattern; varying the dipole physical specifications improves the polarization component ratio and the circularity of the radiation pattern. However, varying the dipole specifications also reduces the gain of the array. For applications requiring higher gains, other methods of realizing high collinear array gains are recommended.

Characterization and Optimization of a Collinear Array of Circularly Polarized Side-Mounted Elements

This paper presents the radiation characteristics of a two-element collinear array of shunt-fed, slanted dipoles side-mounted to a metallic tower. It presents the radiation characteristics of the array as commonly implemented by FM broadcasters and suggests methods on how to optimize these characteristics such as the power gain, pattern circularity, side-lobe reduction, and horizontal-vertical polarization component ratio for the array to better conform to broadcast standards. By determining these characteristics using an advance antenna simulation software, optimization variables are identified, and their optimized values are determined. The optimized values lead to improved radiation characteristics of the array in conforming with broadcast requirements. Results show that adjusting the distance between the dipoles to less than one wavelength reduces the sidelobe of the array radiation pattern; varying the dipole physical specifications improves the polarization component ratio and the circularity of the radiation pattern. However, varying the dipole specifications also reduces the gain of the array. For applications requiring higher gains, other methods of realizing high collinear array gains are recommended.

Inverse Heat Transfer Study of a Power Transmission Line Tower Foundation

Abstract In some northern regions, power transmission lines are built with metal tower footings buried in the permafrost. With a high thermal conductivity, the tower footing has a significant thermal effect on the foundation and the nearby permafrost. Heat transfer models were previously developed to predict the thermal effect with line heat source assumptions, without knowing the exact spatial distribution and temporal variation of the heat source strength. This limited the accuracy of these heat transfer models. In this work, an inverse heat transfer method (IHTM) based on dynamic matrix control (DMC) theory is developed to better estimate the heat source strength representing the tower footing. The methodology is validated with numerical simulations and experimental data. It is found that the distribution of heat source varies spatially and temporally in a more complicated way than what was assumed in previous studies. The inversed heat source is then used to reconstruct the temperature fields in a tower foundation, which provides more accurate heat transfer analysis for design and maintenance of the foundation.

Dynamic Modal Identification of Telecommunication Towers Using Ground Based Radar Interferometry

This work presents a methodology to monitor the dynamic behaviour of tall metallic towers based on ground-based radar interferometry, and apply it to the case of telecommunication towers. Ground-based radar displacement measurements of metallic towers are acquired without installing any Corner Reflector (CR) on the structure. Each structural element of the tower is identified based on its range distance with respect to the radar. The interferometric processing of a time series of radar profiles is used to measure the vibration frequencies of each structural element and estimate the amplitude of its oscillation. A methodology is described to visualize the results and provide a useful tool for the real-time analysis of the dynamic behaviour of metallic towers.

Patterns of sidemount four-bay FM antenna system

This paper presents the radiation characteristics of a 4-bay collinear FM antenna system, both in free-space and with the presence of a metallic tower where the bays are mounted, with the use of powerful computers and accurate antenna simulation software. The radiation characteristics of the array are presented and discussed, such as the total gain, polarization components, circularity, beamwidth and minor lobe of the array. This is to determine the conformity of the array performance with existing standards. The possible effects of the metallic tower and the downward radiation from the minor lobe are emphasized. Being aware with these radiation characteristics, broadcast practitioners can optimize the use of this popular array. Results of numerical analyses show that the array is basically a vertically polarized radiator, the beamwidth is quite small which makes it disadvantageous for high-elevated antenna systems, the metallic tower affects the circularity of the azimuth pattern, and the downward radiation from the minor lobes can cause adverse effects. Adjustments on the basic elements and bay placements are recommended.

On the Eddy Current Losses in Metallic Towers

The existence of magnetic field around high-voltage overhead transmission lines or low-voltage distribution lines is a known fact and well-studied in the literature. However, the interaction of this magnetic field either with transmission or distribution towers has not been investigated. Noteworthy it is to remember that this field is time-varying with a frequency of 50 Hz or 60 Hz depending on the country. In this paper, we studied for the first time the eddy currents in towers which are made of metals. As the geometrical structures of towers are extremely complex to model, we provide a simple approach based on principles of electromagnetism in order to verify the existence of power loss in the form of eddy currents. The frequency-domain finite difference method is adapted in the current study for simulating the proposed model. The importance of such a study is the addition of a new type of power loss to the power network due to the fact that some towers are made of relatively conductive materials.©2020. CBIORE-IJRED. All rights reserved