Terms Of Acceleration Research Articles

Development of programmed trajectories based on the mobility degrees of manipulation robot with a spherical coordinate system for removing oxide film in the production of commercial magnesium

The object of this study is to robotize the technological operation of removing the oxide film from the surface of a magnesium melt poured into continuously moving molds of a casting conveyor for the production of commercial magnesium. To robotize this technological operation, it is proposed to use a two-armed manipulation robot with a spherical coordinate system, which has six degrees of mobility. Software trajectories have been developed according to the degrees of mobility of the manipulation robot in terms of position, speed, and acceleration to perform the technological operation of removing the oxide film from the surface of the magnesium melt poured into the moving molds of the foundry conveyor. Programmed trajectories are described by quadratic polynomials that satisfy restrictions on the values of the generalized coordinate, velocity, and acceleration. These limitations are determined by the design features and energy capabilities of the degrees of mobility drives of the manipulation robot. Programmed trajectories along the first and second degrees of freedom compensate for the continuous movement of the molds of the foundry conveyor. Programmed trajectories along the third and fourth degrees of mobility enable the collection of the oxide film from the surface of the magnesium melt. Programmed trajectories along the fifth and sixth degrees of freedom enable the discharge of the collected oxide film into a special container. The reliability of the developed programmed trajectories is confirmed by the simulation results using MATLAB version R2015b. Based on the results, a cyclogram for controlling a manipulation robot has been constructed to perform the technological operation of removing the oxide film in the production of commercial magnesium. The results could be used in the robotization of technological processes for removing the oxide film in the production of commercial magnesium or similar foundries

Microfabrication of piezoelectric MEMS based on thick LiNbO3 single-crystal films

Microfabrication procedure of piezoelectric micro electro-mechanical systems based on 5 μm thick LiNbO3 films on SiO2/Si substrate at wafer scale including deep dry etching of thick LiNbO3 films by implementing pulsed mode of Ar/SF6 gas was developed. In particular, two (YXlt)/128°/90°LiNbO3-Si cantilevers with tip mass were fabricated and characterized in terms of resonance frequency (511 and 817 Hz), actuation and acceleration sensing capabilities. The quality factor of 89.5 and the electromechanical coupling of 4.8% were estimated from measured frequency dependency of electrical impedance, fitted by using Butterworth–Van Dyke model. The fabricated piezoelectric micro-electro-mechanical systems have demonstrated highly linear displacement with good sensitivity (5.28 ± 0.02 μm V−1) as a function of applied voltage and high sensitivity to vibrations of 667 mV g−1 indicating a suitability of the structure for actuation purposes and for acceleration or frequency sensing with high precision, respectively.

Effect of damper mass on soil-structure displacement in dynamic response to earthquake vibration with finite element modelling

Earthquake is a natural disaster that always occur inside the region of pacific ring of fire. Many structures such as high-rise buildings, bridges, dams and many more failed and take severe damage due to the impact of the strong vibration of the earthquake. A pile foundation is a type of deep footing which is suitable for high-rise buildings founded on clay soils where its function to prevent potential failures such as bearing capacity and collapse. In addition, the problem of tall buildings is prone to sway and damaged when earthquake strike and such vibrations cause the dynamic behaviour of structure to change significantly in terms of excessive lateral displacements and accelerations. Thus, the effect of damper mass on soil-structure displacement in dynamic response to earthquake vibration was determined. The effectiveness of vibration absorber to the single pile structured in clay soil was modelled and simulated in finite element program PLAXIS 3D version 20 with and without the presence of the damper where the inputs were taken from the Sumatera and Chi – chi earthquakes. The problem was modelled and simulated by drawing a geometry, assigning the soil and pile materials input, loading and boundary conditions, meshing generated and staged construction for calculations of displacement structure output in response to dynamic due to earthquake vibration. The displacement-time with the effect of mass of the vibration with and without absorber are presented. The results show a good performance of damper on the single pile structured on soft soil with different types of earthquakes.

Exploring Upper Limb Kinematics in Limited Vision Conditions: Preliminary Insights from 3D Motion Analysis and IMU Data

This study examined upper limb kinematics under simulated visually impaired conditions. By investigating how upper limb movements adapt in these circumstances, we aimed to gain insights that may prove valuable for both healthy populations and those with clinical conditions. Data, including 3D marker-based motion capture and accelerometer readings, were collected from seven healthy volunteers walking on a treadmill at 1.5 m/s under two conditions: without glasses (NG) and with stroboscopic glasses (G). Each walking condition lasted 2 minutes, and two 10-second recordings were analyzed from the midpoint of each session. Contrary to our hypothesis, simulated visual impairment with stroboscopic eyewear at 6Hz did not statistically affect upper limb kinematics, specifically in terms of wrist acceleration and hand distance in the frontal plane. Future research should explore varied visual impairment conditions, extend task durations, and investigate the relationship between subjective gait difficulties and biomechanical data.

Assessment of liquefaction effects on dynamic soil-structure interaction for the 1908 Messina and Reggio Calabria scenario earthquake

Earthquake-induced liquefaction can significantly modify the dynamic response of a soil deposit and interacting structures. In this study, dynamic soil-structure interaction analyses have been performed for a strategic building resting on liquefiable soil. The structure, located in the city of Messina (Sicily, Italy), was built after the strong earthquake of 1908 that caused severe ground shaking and also liquefaction phenomena. Numerical analyses have been conducted with the finite element code PLAXIS3D that adopts the UBC3D-PLM model to simulate the seismic response of liquefiable soils. The advanced UBC3D-PLM model has been calibrated by means of the simulation of cyclic direct simple shear tests (CDSS) using PLAXIS3D software. The seismic behaviour of the soil-structure system on liquefiable soil has been analysed in terms of liquefaction potential, accelerations, response spectra and displacements under three seismograms of the 1908 earthquake. Findings of this study can be of great significance and interest for the prevention and mitigation of seismic liquefaction hazards in areas with high seismic risk.

Utilizing advanced machine learning approaches to assess the seismic fragility of non-engineered masonry structures

Seismic fragility assessment provides a substantial tool for assessing the seismic resilience of these buildings. However, using traditional numerical methods to derive fragility curves poses significant challenges. These methods often overlook the diverse range of buildings found in different regions, as they rely on standardized assumptions and parameters. Consequently, they may not accurately capture the seismic response of various building types. Alternatively, extensive data collection becomes essential to address this knowledge gap by understanding local construction techniques and identifying the relevant parameters. This data is crucial for developing reliable analytical approaches that can accurately derive fragility curves. To overcome these challenges, this research employs four Machine Learning (ML) techniques, namely Support Vector Regression (SVR), Stochastic Gradient Descent (SGD), Random Forest (RF), and Linear Regression (LR), to derive fragility curves for probability of collapse in terms of Peak Ground Acceleration (PGA). To achieve the research objective, a comprehensive input/output dataset consisting of on-site data collected from 646 masonry walls in Malawi is used. Adopted ML models are trained and tested using the entire dataset and then again using only the most highly correlated features. The study includes a comparative analysis of the efficiency and accuracy of each ML approach and the influence of the data used in the analyses. Random Forest (RF) technique emerges as the most efficient ML approach for deriving fragility curves for the surveyed dataset in terms of achieved lowest values for evaluation metrics of the ML methods. This technique scored the lowest Mean Absolute Percentage Error (MAPE) of 16.8 %, and the lowest Root Mean Square Error (RMSE) of 0.0547. These results highlight the potential of ML techniques, particularly RF, in derivation of fragility curves with proper levels of accuracy.

Stationary and Non-Stationary Periodic Flows Mathematical Modelling using Various Vortex Viscosity Models

Introduction. Mathematical modelling of currents is an urgent research topic in the field of hydrodynamics and oceanography. Despite ongoing research in the field of developing accurate and efficient numerical methods for solving Navier-Stokes equations that take into account vortex viscosity, the problems of accurate prediction and control of turbulence remain unresolved. The influence of nonlinear effects in vortex viscosity models on the accuracy of forecasts and their applicability to various flow conditions also remains relevant. The aim of the study is to study the influence of linearized and quadratic bottom friction and two turbulence models on the numerical solution of stationary and non-stationary periodic flows. Special emphasis is placed on comparing numerical results with analytical solutions within the framework of using various models of bottom friction.Materials and Methods. The computational models used in this study are based on a simplified two-dimensional wave model and full three-dimensional Navier-Stokes equations. The classical model of shallow water motion and the 2D model without taking into account dynamic changes in the geometry of the reservoir surface are derived from a system of equations for a spatially inhomogeneous three-dimensional mathematical model of wave hydrodynamics of a shallow reservoir. Analytical solutions were found by linearization of the equations, which obviously has its limitations. A distinction is made between two types of nonlinear effects – nonlinearities caused by higher-order terms in the equations of motion, i. e. terms of advective acceleration and friction, and nonlinear effects caused by geometric nonlinearities, this is due, for example, to different water depths and reservoir widths, which will be important when modelling a real sea.Results. The results of modeling stationary and non-stationary periodic flows in a schematized rectangular basin using linearized bottom friction are presented. The influence of linearization on the numerical solution is investigated in comparison with analytical profiles using models calculating bottom friction in a quadratic formulation. In combination with quadratic bottom friction, two turbulence models are studied: the constant vortex viscosity and the Prandtl mixing length model. The results obtained as a result of three-dimensional modelling are compared with the results of two-dimensional modeling and analytical solutions averaged in depth.Discussion and Conclusion. New approaches to modelling and studying flows with variable vortex viscosity are proposed, including analysis of the influence of linearization and the use of various turbulence models. For the linearized and quadratic formulations of bottom friction, it is proved that the numerical results for the case of stationary flow show great similarity with analytical solutions, since the surface height is much less than the water depth and advection can be neglected. The numerical results for the unsteady flow also show a good agreement with the theory. Unlike analytical solutions, numerical modelling has minor deviations in the long run. The study of flows, within the framework of using various turbulence models, will make it possible to take into account the influence of nonlinear effects in vortex viscosity models on the accuracy of forecasts and their applicability to various flow conditions. The results obtained make it possible to better understand and describe the physical processes occurring in shallow waters. This opens up new possibilities for applying mathematical modelling to predict and analyze the impact of human activities on the marine environment and to solve other problems in the field of oceanology and geophysics.

Medial meniscal lesions increase antero-posterior laxity in knees with anterior cruciate ligament injury.

The aim of this study was to quantify the impact of concomitant meniscal lesions on knee laxity using a triaxial accelerometer in a large population of patients affected by anterior cruciate ligament (ACL) injury. A total of 326 consecutive patients (261 men and 65 women, mean age 31.3 ± 11.3) undergoing primary ACL reconstruction, were preoperatively evaluated through Lachman and pivot shift tests using a triaxial accelerometer to quantify knee laxity. An analysis based on the presence of meniscal tears assessed during surgery was performed to evaluate the impact of meniscal lesions on knee laxity. The anterior tibial translation (Lachman test) presented significantly higher values in patients with medial meniscal lesions (7.3 ± 1.7 mm, p = 0.049) and both medial and lateral meniscal lesions (7.7 ± 1.6 mm, p = 0.001) compared to patients without concomitant meniscal lesions (6.7 ± 1.3 mm). Moreover, patients with both medial and lateral meniscal lesions presented significantly higher values of anterior tibial translation compared to patients with lateral meniscal lesions (p = 0.049). No statistically significant differences were found between the groups in terms of tibial acceleration (pivot shift test). This study demonstrated that the contribution of concomitant meniscal lesions to knee laxity can be objectively quantified using a triaxial accelerometer in ACL-injured knees. In particular, medial meniscus lesions, alone or in association with lateral meniscus lesions, determine a significant increase of the anterior tibial translation compared to knees without meniscus tears. Level IV.

Detailed seismic zoning of the East Kazakhstan region in the Republic of Kazakhstan

Kazakhstan is currently drafting new construction regulations that comply with the major provisions of the Eurocodes. Such regulations are created on the basis of seismic zoning maps of various degrees of detail, developed by our Institute of Seismology using a new methodological approach for Kazakhstan. The article is about creating the first normative map of the Detailed Seismic Zoning on a probabilistic foundation for the Republic of Kazakhstan's East Kazakhstan region. We carried out the probabilistic assessment of seismic hazard using a methodology consistent with the main provisions of Eurocode 8 and updated compared with that used in developing maps of Kazakhstan's General Seismic Zoning and seismic microzoning of Almaty. The most thorough and current data accessible for the area under consideration were combined with contemporary analytical techniques. Updates have been done to not only the databases being used but also the way seismic sources were shown, including active faults now. On a scale of 1:1000000, precise seismic zoning maps of the East Kazakhstan region were created for two probabilities of exceedance: 10 % and 2 % in 50 years in terms of peak ground accelerations and macroseismic intensities. The obtained seismic hazard distribution is generally consistent with the General Seismic Zoning of Kazakhstan's previous findings. However, because active faults were included and a thoroughly revised catalog was used, there are more pronounced zones of increased danger along the fault in the western part of the region. In the west of the territory, acceleration values also increased due to a more accurate consideration of seismotectonic conditions. Zoning maps are the basis for developing new state building regulations of the Republic of Kazakhstan.

Multi-objective trajectory planning for segment assembly robots using a B-spline interpolation- and infeasible-updating non-dominated sorting-based method

The rapid and smooth functioning of segment assembly robots, which is always conflicting, is critical to improving efficiency and ensuring safety during tunneling construction, particularly for the series-actuated robots employed in non-circular shield machines. However, the trade-off between the aforementioned goals has not been explored for trajectory planning in joint space. Less is known about how to acquire superior trade-off Pareto solutions for this constrained multi-objective optimization problem. To fill this gap, this paper proposes a B-spline interpolation- and infeasible-updating non-dominated sorting-based method for multi-objective trajectory planning of shield machine segment assembly robots. In particular, a multi-objective optimization model is detailed in terms of time, acceleration, and jerk of joint trajectories while accounting for operational efficiency and motion smoothness. The given objective functions can be determined using B-spline interpolation and time information based on the known via-points of hydraulic joints. Meanwhile, the constraints are transformed into a limited number of control point-derived forms. Following that, the infeasible-updating non-dominated sorting-based evolutionary algorithm (INSEA) is introduced to solve this problem and find Pareto-optimal solutions. The main improvement is that the multi-objective function information of infeasible solutions is utilized so as to update the non-dominated sorting process, which adaptively applies population division and individual replacement. The findings indicate that the proposed method is capable of executing multi-objective trajectory planning during different stages of the assembly procedure, and the computed metrics are all greater than serval advanced algorithms. Furthermore, on the basis of the proposed INSEA, multi-degree B-spline interpolation provides lower acceleration peaks and smoother global trajectories than common cubic spline curves throughout the process. Therefore, this method can provide researchers with a wide range of alternatives to achieve the optimum trade-off for multi-objective trajectory planning.

A critical assessment of the design displacements of friction pendulum systems

The equivalent linear static procedure suggested in seismic codes for determining the maximum displacements of seismic isolation systems is evaluated comprehensively for friction pendulum isolators with respect to the benchmark nonlinear response history analysis procedure for a set of radii of curvature and coefficients of friction. A large set of selected and scaled near field ground motions recorded on stiff and soft soils are employed in comparative evaluations. It has been observed that equivalent linear static procedure significantly overestimates the maximum isolator displacements for all practical combinations of radius of curvature and friction coefficient. Overestimation is larger for ground motions on soft soils. Alternatively, a practical description of inelastic displacement spectra is introduced where the hazard is defined in terms of the 1-second spectral acceleration accounting for the seismicity and soil class of the site, and friction pendulum isolation systems are characterized by their radius of curvature and nominal friction coefficient. Employing the proposed design spectra in design and production may lead to significant reductions of the isolator sizes. Moreover, realistic estimation of maximum isolator displacements also leads to realistic estimation of isolator stiffness, as well as the internal design forces of both the isolation system and the superstructure through response spectrum analysis under design spectrum.

Performance assessment of steel frame buildings with hybrid self-centering braces under extremely rare far-field earthquakes

This paper investigates the seismic performance enhancement of steel frame buildings using a novel hybrid self-centering braces (HSBs) under extremely rare earthquake events. The hybrid self-centering brace consists of shape memory alloy (SMA) cables and viscoelastic (VE) dampers. A prototype bracing system is designed and fabricated to explore its basic mechanical behavior and working mechanism under cyclic loading, with a focus on its failure modes under large deformation loading condition. A multi-material mechanical model is developed to capture the mechanical behavior and failure of the HSB. Furthermore, five steel frame buildings with different parameterized HSBs are designed and modeled in OpenSees. Nonlinear dynamic analyses and incremental dynamic analyses are conducted on the five case-study frames using 44 far-field ground motions. The risk-based seismic performances of steel buildings with HSB are evaluated to assess the performance of HSB during extremely rare seismic events. The results show that the hybrid self-centering brace exhibits excellent self-centering and energy dissipation capabilities with the maximum equivalent viscous damping ratio reaching 9.4 %. Even under large deformations, VE dampers continue to work effectively after the failure of SMA cables, demonstrating remarkable redundancy. Numerical simulations further reveal that the redundancy of HSB can improve the structural seismic resilience in terms of inter-story drift ratio, residual drift, and floor absolute acceleration. The higher the redundancy of HSB in the case-study frames, the smaller the seismic response and mean annual frequency of exceedance of the engineering demand parameters, thereby indicating a significant improvement in seismic performance.

Considering cut-in behavior in mixed traffic: A longitudinal potential field-based car-following model for autonomous vehicles

To assure safety and comfort for autonomous vehicles (AVs) in the mixed traffic environment, a longitudinal potential field-based car-following model considering the cut-in behavior from an adjacent vehicle is established in this study. The longitudinal potential field (LPF), which includes the cut-in potential field, the hazard potential field and the velocity potential field, is constructed to quantitatively characterize the influence of the surrounding environment on the AVs. The cut-in potential field is created to indicate the possibility of cut-in behavior from the adjacent vehicle, the hazard potential field is intended to depict the risk of colliding with the preceding vehicle, and the velocity potential field is created to show how velocity impacts the following behavior. The proposed model is obtained by calculating the field force in the LPF, and its parameters are calibrated using the genetic algorithm. Comparative simulations are executed to verify the remarkable performance of the proposed model, in terms of acceleration, velocity, and headway tracking as well as responding to the cut-in behavior under three different driving conditions.

Seismic loss assessment of code-compliant moment-resisting RC buildings located on different soil conditions of Mexico City

This research aims to estimate the expected economic losses associated with the repair cost of a set of code-compliant moment-resisting reinforced concrete buildings located on different soil conditions in Mexico City. The loss assessment methodology is based on the second generation of the Performance-Based Earthquake Engineering (PBEE) framework, which quantifies the seismic performance of buildings in terms of metrics such as economic losses, downtime, and casualties, which are more meaningful to owners and stakeholders for the decision-making process. The methodology uses a probabilistic approach that takes into account uncertainties in seismic intensity, structural response, component damage, and consequence prediction. The seismic response of structures was calculated in terms of inter-story drifts and floor accelerations to assess the damage to their structural and non-structural components. In addition, taking into account the seismic hazard of the site, the expected annual losses (EAL) are calculated to provide insight into the seismic performance evaluation of structures with different characteristics in terms of the financial impact in seismic-prone regions like Mexico City.

Parametric pushover curve model for seismic performance assessment of building stock

AbstractAn effective assessment of the seismic risk of building stock is important for informing stakeholders and developing strategies to improve community seismic resilience. To address this need, a parametric pushover curve model for seismic performance assessment of building stock is introduced. The model employs twelve parameters for estimating the trilinear pushover curve. The models of these parameters are developed specifically for reinforced concrete and masonry buildings in Slovenia by focusing on the low level of knowledge about the building. Consequently, it can be used for preliminary studies of seismic performance assessment of building stock to raise awareness about seismic risk. To evaluate its efficacy, the model was applied to assess the seismic performance of the University of Ljubljana’s building stock. Because of uncertainties arising from the lack of knowledge about the buildings and the associated assumptions, the results were interpreted relative to those obtained for a new building stock scenario. The case study revealed that the seismic capacity in terms of the limit state peak ground acceleration of the building stock is only half of what would be expected in the new building stock scenario, highlighting a significant seismic risk. These findings emphasise the need for systematic efforts to enhance the seismic safety of the building stock under consideration. Further research is recommended to explore the model's accuracy concerning the level of knowledge about the building, which will contribute to a better understanding of its applicability.

Optimization of vibration control using a hybrid scheme with sliding‐mode and positive position feedback

AbstractThis article presents the design of a nonlinear hybrid controller for an underactuated Duffing oscillator with 2 degrees of freedom. The main control purpose is to reduce the frequency‐response to specific resonant‐frequencies while maintaining its robustness to external disturbances. The resulting hybrid controller uses sliding mode control (SMC) with a positive position feedback (PPF) scheme. This is structured such that the SMC provides system robustness and tracking, while the PPF allows damping specific resonant frequencies. The system was evaluated using frequency sweeps in terms of acceleration in the second degree of freedom. In this case, the control input is applied through the first degree of freedom. Moreover, multi‐objective optimization is implemented to tune of the control parameters. Simulation results show that the system response to external vibrations can be reduced up to 83.88% by using the proposed PPF + SMC scheme.

Influence of wind and seismic ground motion directionality on the dynamic response of four-legged jacket-supported Offshore Wind Turbines

This paper aims at investigating the influence of the direction of wind and seismic ground motion on the structural response of four-legged jacket support substructures for bottom-fixed Offshore Wind Turbines located in areas with non-negligible seismic risk. To do that, a parametric analysis that considers thirteen seismic shaking directions, seven wind directions and four earthquake records is carried out. The results are presented in terms of accelerations, axial forces, bending moments and shear forces in the jacket substructure. The NREL 5 MW wind turbine supported on the jacket designed for the phase I of the OC4 project is considered. The response of the system is simulated using an OpenFAST model that takes into account multi-support seismic input, soil–structure interaction and kinematic interaction. The results show that load combinations with aligned wind and ground motion directions are never the worst-case scenario. On the contrary, the largest accelerations are found when the shaking direction acts along the side-to-side direction, and the most significant internal forces are usually found when the ground motion is aligned with one of the diagonals of the base of the jacket and not aligned with the wind direction. The paper also discusses the specific ranges of the angle of misalignment between wind and seismic shaking directions within which the maximum internal forces are expected to be found.

Global Sea Level Change Rate, Acceleration and Its Components from 1993 to 2016

Investigating the global sea level budget is essential to quantify the total sea level change (altimetry) and its components, including the steric sea level change and the ocean mass change (gravity), where the latter is mainly attributed to four mass-driven components (Greenland, Antarctica, glaciers and land water storage). In this study, a 24-year global ocean mass change is derived by the joint use of Tongji-LEO2021 and Tongji-Grace2018 monthly gravity field models over 1993–2016, with which the sea level budgets in terms of rate and acceleration are investigated over global oceans within the latitudes 66oN to 66oS together with the IGG-SLR-HYBRID gravity field models, altimetry, steric and four mass-driven components. The statistical results show that the global mean ocean mass change rate accounts for ∼54% of 2.85 ± 0.30 mm/year of global mean total sea level change. The accelerations of global mean total sea level change and its components are 0.145 ± 0.025 mm/year2 (altimetry), 0.003 ± 0.021 mm/year2 (steric), 0.139 ± 0.047 mm/year2 (ocean mass from Tongji), and 0.137 ± 0.010 mm/year2 (the sum of mass-driven components) respectively, indicating that the global sea level budget in terms of acceleration can be closed and nearly no acceleration exists in the global mean steric sea level change for the period 1993–2016.

Calculation and experimental studies for the spent nuclear fuel shipping cask sealing assembly

One of the safety requirements regarding the shipping cask for spent nuclear fuel is that its leak-tightness should be maintained by preserving the cask body structural integrity and the sealing system tightness under normal and accident transportation conditions. The cask under design has a cylindrical process penetration (port) in its bottomб which is sealed using a plug with a radial seal composed of two rubber O-rings. The cask sealing assembly design was justified by the ANSYS LS-DYNA code calculation results. In particular, the strains of the cask components were calculated when dropped from a height of 1 m with the sealing assembly hitting a vertical bar. The cask was concluded to be leak-tight or leaky based on the strain nature and amount. To verify the adequacy of the results, computer-aided and realistic simulations were undertaken with a 1/2.5 scale mockup cask dropped on a bar from a height of 1 m. The computational and experimental results show a good agreement in terms of the impact response accelerations (overloads) for the mockup cask and bar collision and in terms of the plastic strains for the key components of the mockup bottom port sealing assembly. This proves the adequacy of the numerical cask model that has been developed and the efficiency of the LS-DYNA simulations. The inner rubber O ring compression is reduced by the plastic strains in the cask’s bottom port area, leading to a loose inner radial seal, as shown by the calculations. But the outer seal remains leak-tight, ensuring so the mockup cask tightness. The physical test results have also confirmed that the mockup cask remains leak-tight.

Multiparameter study for a new ground-based telescope in Egypt

ABSTRACT A multiparameter analysis was conducted to evaluate the impact of meteorological parameters, night sky brightness and seismic hazards on proposed sites for the new optical/infrared Egyptian astronomical telescope. The European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) data set is used to obtain the following meteorological parameters: total cloud coverage fraction, precipitable water vapour, relative humidity, wind speed and direction, and air temperature. To estimate the aerosol optical depth, we used the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). Light pollution over the candidate sites was measured using the Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band. In order to assess the seismic hazards for the candidate sites, the seismic input in terms of maximum acceleration and response spectra was computed using a physics-based ground motion approach to assess the seismic hazards and, consequently, the designation of a seismic-resistant structure for the proposed sites. Of the seven nominated sites, two sites are found to have the best measurements and might be considered as future sites for the new Egyptian astronomical telescope. The first site is located in the south of the Sinai peninsula, while the second site is located in the Red Sea mountains region.