Tower Model Research Articles

Investigation of the simultaneous effect of fouling and ambient conditions on cooling performance and water consumption of a wet cooling tower

The cooling performance and water consumption of the wet cooling tower are two important parameters that must be balanced to achieve the optimum performance of this industrial component in its operating condition. The performance of the wet cooling towers can be analyzed by the thermodynamic models. On the other hand, fouling can drastically affect the cooling tower performance. In the present research, a thermodynamic model is developed and validated with numerical and experimental results in order to investigate the wet cooling tower's water consumption and cooling performance under various weather conditions. The model includes an accurate cooling tower model, considering the buoyancy force and droplets evaporation in the rain and spray zones. To achieve accurate results, an optimization algorithm is also utilized to solve the equations. This model was then applied to analyze the water consumption and cooling performance of a small cooling tower during the hottest months of Iran (July/August) in Ahvaz, Tabriz, and Yazd with different climate conditions. The non-dimensional parameter of the fill performance index (ηF) was used to describe the fouling in the packing. So, considering the simultaneous effects of the buoyancy force and droplet evaporation in the rain and spray zones and fouling in packing in the developed model, with utilizing a new and accurate method to solve the model's equation to analyze the performance of the wet cooling towers under different conditions, are the novelty of this study. Based on the results, a rise in fouling decreases the fill performance index. A decline in the fill performance index from 2.4 to 1.2 increases the monthly average of the cooling tower outlet water temperature from 24.24, 21.21, and 21.19 °C to 25.94, 24.14, and 24.11 °C in Ahvaz, Tabriz, and Yazd, respectively, while the monthly water consumption decreases from 1.74, 1.87, and 2.22 m3h to 0.99, 1.10, and 1.29 m3h in the mentioned cities, respectively. The maximum outlet water temperature was observed in case ηF=1.2, while the maximum water consumption occurred in ηF=2.4. So, ambient conditions and fouling simultaneously affect the performance of the cooling tower, which is well predicted by the suggested model.

Multi-metric evaluation of the optimal intensity measure for mainshock-aftershock fragility analysis of transmission towers

Identifying the optimal intensity measure (IM) contributes to reducing uncertainties in probabilistic seismic demand models (PSDM) and enhancing confidence of their results. Although many studies have discussed appropriate IMs for mainshocks, relatively less attention is paid to the potential aftershock effect. In particularly, the optimal IMs for developing PSDM of transmission towers subjected to sequential earthquakes has not been well studied previously. Therefore, this paper conducts a multi-metric evaluation to identify the optimal IM in the context of mainshock-aftershock (MSAS) fragility analysis of transmission towers. This evaluation process includes collecting a set of ground motions recorded with varying magnitudes and fault distances to construct MSAS sequences, followed by comprehensive discussions on their seismic characteristics by comparing thirty-six potential IMs candidates. Additionally, a finite element model of a transmission tower is established to numerically investigate different engineering demand parameters (EDP) of the tower under the selected MSAS sequences. The optimal PSDM of the transmission tower is determined by evaluating each couple of IM−EDP on a logarithmic space using multiple evaluation metrics. Through this analysis, the first-mode spectral acceleration Sa(T1,ξ) is identified as the optimal IM as it exhibits excellent correlation, efficiency, practicality and proficiency with the EDPs of the transmission tower, especially with the inter-segment displacement ratio. Consequently, seismic fragility curves of the transmission tower are developed using the optimal IM. The research outcome can contribute to improving the understanding of the probabilistic assessment of transmission towers in the MSAS scenario.

An experimental study on the influence of wind-wave-current coupling effect on the global performance of a 12 MW semi-submersible floating wind turbine

Investigating the coupling effect between different marine environmental conditions is essential to understand the dynamic response of wind turbines. This paper presents the study findings from the model tests conducted in a wave basin, exploring the coupling effect of wind, waves, and currents on the global performance of a 1:70 scale model 12 MW semi-submersible floating wind turbine (FWT). A multi-blade large-scale wind generation system with a rectifier network was improved and fabricated to provide a reliable wind field for the experiment. The stiffness-matched and geometry-matched tower models were designed and fabricated, achieving an accurate simulation of the tower's flexibility and windward areas and their impact on the global dynamic response. Following the calibration of marine environmental conditions and the characterization of the model FWT system, the study focused on the operational and extreme responses of the FWT concept. The aerodynamic damping effect of wind in pitch and surge motions is remarkable, especially in pitch motion, primarily manifesting by reducing the standard deviation of motions. Mooring load responses are predominantly induced by the hydrodynamic effect, with the wave-frequency response gradually becoming dominant as wave parameters increase. Tower-top load responses are primarily induced by the hydrodynamic effect of waves and the aerodynamic load effect of wind. Furthermore, the phenomenon where the action of current strengthens the aerodynamic damping effect of wind is observed. The coupling effect between wind and current amplifies surge motion while diminishing pitch motion, effectively reducing the tower-top and tower-base load responses.

High‐fidelity finite element modeling of the seismic response of prefabricated steel stairs

AbstractAdvancing the seismic resilience of building systems is an active area of research in earthquake engineering. Ensuring safe egress in and out of buildings during extreme events, such as an earthquake, is essential to supporting this effort. To this end, understanding the seismic response of stairs facilitates the robust design of egress systems to ensure they can remain operable after an earthquake. From prior earthquake events and physical experiments, it is understood that stairs with a flight to landing fixed connection at multiple levels within a building are prone to damage. In addition, the stair system with flight to landing fixed attachments may affect the dynamic behavior of the building. To accommodate seismic inter‐story drifts, a kinematically free connection between the stairs and landing has been proposed. Herein this connection is referred to as a drift‐compatible stair connection. To investigate and aid in the design of such a connection, a unique set of shake table experiments were conducted at the University of Nevada, Reno. In this paper, an overview of these tests is presented, and a high‐fidelity finite element model of the tested stair system is used to predict the responses measured during these experiments. Developed in Abaqus, the robustness of the modeled stair unit is investigated considering a variety of contrasting connections, namely, drift‐compatible connections, fixed ends and one end fixed and the other free. Results from these numerical simulations offer guidance towards development of simplified models of multi‐level stair subsystems. Such models are needed when investigating seismic resilience of building systems across a wider range of hazard levels. Furthermore, best practices observed utilizing the models developed and evaluated herein against experimental data will be useful for subsequent analysis of larger stair tower models, such as the 10‐story stair system implemented in the NHERI Tall Wood mass timber building with post‐tensioned rocking walls, conducted in 2023 at the UC San Diego Large High‐Performance Outdoor Shake Table.

Transmission tower bolt-loosening time–frequency analysis and localization method considering time-varying characteristics

To address the issues of high concealment and difficult positioning of loose bolts in transmission towers, this paper proposes a new method for locating loose bolts in transmission towers. In this method, we divide the vibration response of the transmission tower into low-frequency signals of 2–25 Hz and high-frequency signals of 25–75 Hz. For the low-frequency signals, the single signal component is obtained by adaptive Chirp mode decomposition and uses the general demodulation transformation to deeply denoise the non-modal information. Since frequency characteristics themselves do not contain time information, considering the importance of time information for positioning, we propose a low-frequency time-varying frequency feature that preserves time characteristics based on synchronous wavelet transform and peak search. For the high-frequency signals, we use singular value decomposition to remove signal outliers caused by pulse excitation and eliminate forced vibrations through wavelet packet transform. Without altering its inherent characteristics, this method enables high-frequency time-domain signals to better represent the nonlinear characteristics of transmission towers. Furthermore, based on the powerful capabilities of Timesnet and Transformer in dealing with time series data, we propose a fault diagnosis model, which ultimately achieves the positioning of loose bolts in transmission towers. The bolt node model proves that this approach can better represent the loose bolt characteristics, and the transmission tower model verifies the effectiveness of this approach in locating loose bolts in transmission towers. Finally, bolt-loosening tests were conducted on a 110 kV transmission tower, and the accuracy of the positioning results reached 92.8%, demonstrating the effectiveness and efficiency of this method in practical positioning applications.

Velocity-pressure admittance for structural analysis of large cooling towers against strong winds

To facilitate dynamic structural analyses of large cooling towers subjected to strong winds in structural design and safety assessments, the auto-spectra of the local wind pressures on the tower shell are required. To avoid expensive and laborious physical model tests, Pirner provided empirical normalized pressure spectra for direct use, which imply that the concept of velocity-pressure admittance can be applied in the windward region on the tower shell. However, Pirner's empirical results are subjected to the fact that the dependence of pressure spectra on height or turbulence intensity of the oncoming flow is wrongfully neglected. To this end, velocity-pressure admittances are measured at various heights on a 1:200 scaled tower model in an atmospheric boundary layer wind tunnel, and unified formulae for velocity-pressure admittance on windward region of large cooling towers are fitted out for use considering the turbulence intensity effects. The unified formulae are further validated using data measured on a 167 m high full-scale cooling tower in China. The full-scale/empirical formulae comparison indicates that the unified formulae for velocity-pressure admittance proposed are applicable on the windward side [0 degrees, 70 degrees]; while a constant of 1 should be utilized as the normalized power spectral density in the circumferential region [70 degrees, 180 degrees] in structural analyses.

Bayesian model updating of super high‐rise building for construction simulation

SummaryA finite element model was established using SAP2000 software for the C1 tower, a super high‐rise building in the second phase of the Nanjing Financial City project, and the construction process of the tower was simulated. The C1 tower adopts a frame core tube extension arm and ring truss structure system, with 87 floors above ground and five floors underground. The roof structure has an elevation of 416.6 m. Precise measurements of inter‐story compression deformation were conducted using advanced surveying equipment. Sensitivity analysis, based on the finite difference method, identified the shear wall elastic modulus, frame column elastic modulus, steel beam elastic modulus, and shear wall unit weight as four highly influential parameters. Employing the Bayesian principle, the Markov Chain Monte Carlo (MCMC) method was applied to determine the posterior density probability function of the parameters targeted for modification. Subsequently, the Metropolis–Hastings (MH) sampling algorithm was employed to refine the C1 Tower model. This refinement significantly reduced the root mean square error between the measured and simulated vertical displacements, achieving an error reduction of approximately 10% from 6.082 to around 2.160. The modified material parameters, for the most part, adhered to a normal distribution assumption and exhibited mean values in the posterior probability density functions for the elastic modulus of Q345 steel beams, C70 frame columns, and C60 shear walls. Compared to the initial finite element parameters, the variation range was approximately 13% to 17%. These results serve as a validation of the effectiveness of the proposed method.

TLD optimal vibration control for elevated concrete water towers

Considering the influence of earthquake and wind on the water tower, the analysis model of the elevated concrete water tower and its foundation is established. The dynamic response model and damping measures considering liquid–solid-soil interaction are determined. The influence of two kinds of circular tuned liquid dampers on dynamic response of elevated concrete water tower is studied. The results show that the peak values of displacement, acceleration and stress under the simultaneous action of wind field and earthquake exceed the peak superposition under the single factor of wind field and earthquake. However, the peak value of the liquid sloshing amplitude of the water tower under the earthquake-wind coupling does not exceed the sum of the wave peak values under the action of earthquake and wind alone. In addition, both circular TLDS have significant damping effect on elevated concrete water towers, but the damping effect of saturated salt water as TLD tempering fluid is better than that of pure water.

Graph neural network recommendation algorithm based on improved dual tower model

In this era of information explosion, recommendation systems play a key role in helping users to uncover content of interest among massive amounts of information. Pursuing a breadth of recall while maintaining accuracy is a core challenge for current recommendation systems. In this paper, we propose a new recommendation algorithm model, the interactive higher-order dual tower (IHDT), which improves current models by adding interactivity and higher-order feature learning between the dual tower neural networks. A heterogeneous graph is constructed containing different types of nodes, such as users, items, and attributes, extracting richer feature representations through meta-paths. To achieve feature interaction, an interactive learning mechanism is introduced to inject relevant features between the user and project towers. Additionally, this method utilizes graph convolutional networks for higher-order feature learning, pooling the node embeddings of the twin towers to obtain enhanced end-user and item representations. IHDT was evaluated on the MovieLens dataset and outperformed multiple baseline methods. Ablation experiments verified the contribution of interactive learning and high-order GCN components.

Wind-Induced Response Analysis of the Transmission Tower-Line System Considering the Joint Effect

Wind load is one of the main control loads of transmission tower-line systems. Numerical simulation is the main method for studying the structural wind-induced response. The establishment of a refined transmission tower simulation model is the basis for accurately analyzing the dynamic response of a transmission tower-line system under a wind load. This paper first considered the mechanical properties of bolted joints under cyclic loading and established a transmission tower-line system model considering the joint effects. Then, the wind load was generated by the harmonic superposition method, and the wind dynamic time-history analysis of the tower-line system was conducted. The influence of the joint effect on the wind-induced response of the transmission tower-line system was studied, and the effects of turbulence intensity and wind attack angle on the bolted joint slip effect were discussed. The results showed that the joint effect significantly increased the displacement response of the transmission tower subjected to wind loads and affected the normal service performance of the tower-line system. When the turbulence intensity is 10%, the top displacement of the tower model considering the joint effect is approximately 2 times that of the ideal rigid frame model. After considering the joint effect, the additional [Formula: see text] effect caused by the increased displacement resulted in an increase in the stress of 75.6% members, and the maximum stress of the main member was located near the upper diaphragm of the tower leg. Therefore, considering the joint slip effect in angle steel transmission towers can improve the accuracy of the dynamic response analysis of transmission lines.

Finite Element Model of Concrete-Filled, Fiber-Reinforced Polymer Tubes for Small-Scale Wind Turbine Towers

The finite element method was used to study the feasibility of concrete-filled, fiber-reinforced polymer tubes (CFFTs) for small-scale wind turbine towers in remote areas. Although CFFTs have been successfully employed for a variety of structural applications, their use for wind turbine towers is novel and has yet to be investigated in detail. The objective of the study was to identify, for the first time, the most important parameters for design and compare the behavior of CFFT towers versus conventional steel and concrete towers. The model was first validated using experimental results reported in the literature followed by a series of parametric studies to evaluate the importance of several key parameters. In the first phase, the effect of different geometric properties (taper and concrete filling ratio) and reinforcement configurations (FRP laminate configuration, steel reinforcement ratio, and prestressing level) were investigated for cantilever tower models with concentrated lateral loads. A 10 m high CFFT wind turbine tower model was subsequently modeled and studied under different loading configurations. The influence of the height-to-diameter (h/D) ratio on cantilever CFFT models was also studied and a conservative preliminary design that can be refined for specific turbine systems and wind conditions was adopted using the h/D ratio. The CFFT tower model was compared to concrete and steel tubular models with similar geometry to study the advantages of CFFT towers and showed that CFFTs can be an efficient alternative.

Seasonal performance research of heat-source tower systems using different work materials

Abstract The heat-source tower system has been evaluated in an enthalpy difference laboratory. This study analyzes the seasonal performance under various operating situations and fluid quality. In the summer and fall seasons, water is used as the circulating fluid in the tower. In the spring and winter seasons, glycol solution is used as the circulating fluid. Some parameters of the heat-source tower (e.g. the temperature of the solution inlet and outlet, the flow rate of the solution inlet and outlet, the temperature of the air inlet and outlet, the inlet air volume and the moisture content of the inlet air) are considered and measured to obtain its heat transfer characteristics. The simulation model of heat-source tower is constructed based on the mechanism of heat and mass transfer. This model is validated by the experimental results. The heat exchange and latent heat exchange of the system are analyzed under different parameters, as well as the variation law of inlet and outlet temperature and moisture content differences. The results show that the system has solution moisture absorption during winter operation. However, for every 9000 m3/h increase in air volume, the rate of solution dilution decreases between 9 and 43%. The rate of solution dilution is reduced by 11–31% for every 1°C in addition to the inlet solution temperature. Meanwhile, the heat dissipation in summer is about 2.8 times of the heat dissipation in winter.

Rational modeling of a wind unit tower taken into account of the features of its dynamic characteristics

Nowadays the level of development of finite element (FE) calculation systems allows us to count on the maximum level of design solutions quality, provided that is created an adequate and at the same time simple design model, which directly determines the level of accuracy of the results obtained when determining the parameters of the stress-strain state, as well as dynamic characteristics of buildings and structures. It is fundamentally necessary for the designer to know the degree of influence of various factors to the creation of a finite element design model on the dynamic response of the design object. There is no doubt the relevance of the problem of identifying the features of modeling tower-type structures, which will simplify the work of an engineer and at the same time reach a qualitatively new level in making design decisions. The purpose of this work is a comprehensive assessment of the influence of the features of creating a design model to the resulting parameter - the frequency behavior of a tubular tower for wind turbines which is the most popular at wind parks in Russia over the past two decades. For numerical research was used the domestic design complex SCAD Office. To create calculation models and perform a comparative analysis of the resulting parameters of tubular towers were used FE types 41, 42, 44, and 50. When determining the influence of the finite element type calculations were made for a cylindrical tower with fixed parameters, taking into account changes in the type and size of the FE. In the calculations the evaluating factors were: changing in the main and equivalent stresses, as well as the change in the frequency of the first form of own oscillations. When comparing the values of the main and equivalent stresses, the plate of the third row from the base was taken as the calculated one.

Dynamic Validation and Assessment of a Historical Bell Tower

The work investigates the dynamic validation and seismic assessment of a bell tower located in Caserta Vecchia, emphasizing its relevance in structural engineering. Given the tower historical significance and possible vulnerability, understanding its structural behaviour under seismic loading is vital for preservation efforts. To capture the bell tower structural intricacies, advanced photogrammetric surveying techniques were utilized. This produced a detailed 3D model of the bell tower, which was subsequently integrated into the Abaqus software for finite element analysis. This approach facilitated a comprehensive examination of the tower structural dynamics and vibrational characteristics. The robustness of the study has been further enhanced through a validation process. Frequency analysis outcomes from Abaqus were cross-referenced with real-world seismic data collected using structural health monitoring (SHM) systems. This seismic data was analyzed using the Frequency Domain Decomposition (FDD) technique. This method ensured that the analytical model results were consistent with observed seismic responses, thereby validating the model’s accuracy and reliability. Further dynamic analyses were conducted to evaluate the bell tower potential vulnerabilities during high-intensity seismic events. These analyses are essential for predicting the structural response and potential damage patterns during earthquakes, facilitating better preparedness and mitigation strategies. The applicability of the methodologies used in similar contexts offers opportunities for advancing heritage preservation and optimizing the seismic safety of such complex structures.

Construction and implementation of a mathematical model for damping vibrations of high-rise buildings and structures using reactive dampers

The problem of developing a computational model of an active vibration damping system of a high-rise building during an earthquake using a simple and suitable calculation scheme for high-rise buildings is considered. An approximate finite element model is presented that adequately describes the dynamic characteristics of a high-rise building. A mathematical model of a steel lattice tower is considered as an example. The ratio equations and displacement difference equations describing the behavior of reactive dampers installed in the tower are presented. An approach to optimizing the parameters of relative motion is presented. The calculation of vibration damping of a tower with reactive dampers installed on one and two levels is shown. The classification of forces with different physical properties and affecting the movement of mechanical systems is presented.

Research on the digital protection and three-dimensional modeling technology of ancient buildings

Abstract The starting point of ancient architecture digitization and 3D reconstruction research is data acquisition. Thus, this paper mainly analyzes the processing of 3D laser scanning data and the construction accuracy of 3D reconstruction models of ancient buildings based on point cloud data. This paper discusses the basic theory of point cloud data and the preprocessing of point cloud data, including point cloud splicing, point cloud denoising, point cloud streamlining, point cloud segmentation, and other methods and applicability are discussed in detail. The boundary extraction algorithm based on RANSAC and the graph cut algorithm are utilized to obtain the main frame line of the building, and a proposed method for reconstruction based on multi-view projection is proposed. Classify laser point cloud samples from ancient buildings, calculate each wall color’s R, G, and B values, and obtain preliminary classifications of laser point cloud data categories. The RANSAC algorithm was used to extract the point cloud data plane extraction peak of the ancient tower building, combined with the three-dimensional modeling coordinate difference of the test points, to analyze the accuracy of the three-dimensional modeling technology of ancient buildings in this paper. The number of plane extraction points of the RANSAC algorithm is 9504, and the standard deviation is 0.0505, which is close to 0. The results are more accurate, and the extraction effect has a certain degree of superiority. The plane coordinate deviation of the reconstruction model of the ancient tower is mainly concentrated in the range of 0.10~0.40m, and the individual coordinate difference is more than 0.10m. The errors in the x -direction and y -direction are ±0.18m and ±0.23m, respectively, and it can be seen from the results of the error calculation that the three-dimensional reconstruction plan of the building proposed in this paper can complete the reconstruction of the three-dimensional model of the building with a high degree of accuracy.

The Construction of Online Interactive Teaching Mode of Cross-border E-commerce English in Colleges and Universities under the Background of Internet

Abstract In this paper, we first constructed an online interactive English teaching model through the interaction hierarchy tower model and adopted a data-driven social cognitive network analysis approach to explore the evolutionary dynamics of cross-border e-commerce English learning communities in higher education and their potential correlation with the development of participants’ interaction patterns. Then, the online synchronous and asynchronous interaction patterns of learners are compared and integrated by extracting the characteristics of online interactive teaching learners. Finally, an instructional design for an online English for Cross-border E-commerce course was used to explore the differences and associations between online interactive teaching modes. The results show that in the teaching experiment, students have 39 nodes in the synchronous interaction network (SMN) and 34 nodes in the asynchronous interaction network (UMN), and the degree centrality and eigenvector centrality Rank=4.07 and 3.15 of the SMN are also significantly higher than those of the three interaction networks. The SMN interaction model is found to be the most efficient in the online interaction teaching process. This study helps to improve the dynamic regulation and precise guidance of the online learning process for cross-border e-commerce English, which ultimately enhances the quality of online teaching.

Features of a finite-element modeling of a tubular tower for a wind-power unit

Introduction. Being indisputably relevant, an identification of the features of modeling tower structures can simplify the work of engineers and simultaneously move the design decision-making to a qualitatively new level.Aim. To assess the effect, caused by some particular features of a computational modelling, on the resulting parameter, representing the frequency behavior of a tubular tower for wind-power units.Materials and Methods. Numerical studies were conducted using a domestic SCAD Office programming and computing suite. In computational modeling, 41st, 42nd, 44th and 50th FE types were used. During the assessment of effects, caused by the finite element type, calculations of a cylindrical tower with fixed parameters were performed, taking into account variations in the type and size of the FE. Estimating factors in calculations included: variations in stresses, as well as in the frequency of first-mode natural oscillations. During the comparison of stress values, the plate of the third from the fixed base row was taken as the design one. Turbowind T600-48 and Eviag EV 100 were considered as wind turbines.Results. A sufficient discretization value of the computational model for determining the frequency of natural oscillations equals to nR = 12, since a further increase in the value of nR will lead to variations in the frequency of natural oscillations by less than 1%. The individual frequencies of 0.275 and 0.825 Hz were determined for an Eviag EV 100 wind turbine. For a Turbowind T600-48, the range of resonant frequencies is determined due to the presence of a variable rotor speed: starting and maximum frequency ranges of 0.255–0.765 and 0.383–1.149 Hz, respectively.Conclusions. During the modeling of a tower in the SCAD Office PCS, it is feasible to use the 44th type of finite elements, taking into account the obtained sufficient discretization value. The obtained spectrum of natural and resonant frequencies allows avoiding the appearance of a resonant effect when making design decisions.

Transmission Tower category Identification from Airborne LiDAR Point Clouds based on Shape Curve

Using airborne LiDAR point cloud data to reconstruct the three-dimensional (3D) models of the transmission towers is crucial for ensuring power transmission safety. To enhance the models’ accuracy, knowing the tower categories is essential. However, there are few studies on the identification of tower categories at present. The existing studies have various shortcomings. Aiming at the problem of tower category identification in the application of airborne LiDAR point clouds in a smart grid, a transmission tower category identification method based on the shape curve is proposed. Firstly, a tower curve database is established based on relevant standards. Then, we employ three methods, namely dynamic time warping (DTW) distance, Hausdorff distance, and DTW-Hausdorff distance, to calculate the similarity indexes between the tower point cloud shape curves and those in the database. These indexes are used to determine the tower category. Finally, this method is tested using point clouds from transmission corridors. The experimental results show that the tower identification accuracy of DTW-Hausdorff distance is 94.0%. The tower category identification accuracy can reach 88.0%. The F-score used as the overall evaluation index of the tower identification effect is 90.9%. When employed as a similarity index, the tower identification effect is the best.

Performance evaluation and feasibility study of a cooling tower model for zero liquid discharge-desalination processes

Performance evaluation and feasibility study of a cooling tower model for zero liquid discharge-desalination processes