Vibration Levels Research Articles

Evaluation and implication of noise and vibration levels to the operators and proxy population around selected block molding industries in Ibadan, Nigeria

Introduction: Block-making industries owned by private individuals are cited in cities to utilize the existing market opportunity of supplying concrete blocks to developers. The study aimed to measure noise and vibration levels at selected block-molding industries and assess their health implications. Methods: The study design involves twenty-five block molding industries randomly selected in the Ibadan metropolis. These industries voluntarily agreed to participate in the research, and measurements were done between January and May 2022. The noise and vibration levels were measured using a digital multi-function environmental meter, Model DT-8820, and a vibration meter, Model VM-6360, respectively. Results: An overall mean noise level of 101.81 dB(A), 85.62 dB(A), 76.40 dB(A), 70.21 dB(A), 65.91 dB(A), and 63.61 dB(A) at 0, 10, 20, 30, 40 m, respectively, away from the source to residential buildings were obtained. Results indicate that the noise level at 0 m and 10 m exceeded the occupational noise level standard. The results obtained for the vibration levels on the hand of the operators ranged from 42.2 ms-2 to 59.7 ms-2 and these exceeded the occupational vibration level standard. This may indicate that the operators of the block-moulding machine may be exposed to various adverse health detriments due to high noise and vibration levels at their workplace. Conclusion: The study recommends using safety gadgets such as hearing protection and anti-vibration gloves for workers in these industries. Moreover, environmental education and awareness should be carried out, and residential structures should be situated at least 20 meters from the block industries.

Monitoring of ground and building vibrations caused by train wheel defects

This paper describes a study performed on train wheel defects and their effect on rail vibrations. The paper describes a test setup allowing the researchers to capture ground vibrations at the desired level of detail to prove to what extend wheel quality influences ground vibration levels and associated nuisance to people. The analysis of the measurement signals shows that the individual axles of a passing train can be detected excellently with the signal from the axle detection and the vibration sensors. The signals from various sensors in the measurement setup are synchronized with high time accuracy, making it possible to overlay the time interval of an axis passage over the signal from the vibration measurements. This makes it possible to track vibrations at bogie and axle level. The distance of measurement points from the track is ultimately the determining factor for the extent to which vibrations are dominated by an axle, a bogie, a wagon or the entire train. In addition, direct wheel roundness measurements have been performed for trains that appear to have defect wheels based on ground vibration data. With the track based measurements, the ground vibration measurements and the direct wheel measurements an unique data set has been generated, allowing for an evaluation of the importance of defect train wheel from the perspective of vibrations nuisance to the environment. Relations of measured vibrations to other parameters, both rolling stock related and environmental parameters were investigated based on the generated set of data. The analysis on the data reveals interesting relations between train wheel parameters and ground vibrations, which are discussed in this paper.

Exploring Human-Crowd Interaction in Structural Monitoring: Insights from Two Decades of Events at the G. Meazza stadium

In recent times, a growing body of research has emerged to evaluate how structures respond to dynamic forces generated by human activities. Notably, stadiums and sports arenas require significant attention due to the presence of spectators during events such as football matches and concerts. The way the crowd behaves during such events causes significant vibration levels which can be critical for both human comfort and structural integrity. Generally, the interaction between humans and structures is a significant concern in structural health monitoring. While a structure behavior may be considered deterministic (albeit challenging to predict), the forces exerted by crowds are inherently variable and uncontrollable. A critical aspect is related to the fact that studying the crowd behavior is a complex task, because modelling it not only implies engineering knowledge but also taking into account other complex factors, e.g., the social and psychological aspects of human behavior. In this context, this paper uniquely contributes by presenting and analyzing real-world vibration data gathered by the monitoring system of the G. Meazza stadium in Milan. This extensive dataset, built over the past 15 years, represents a one-of-a-kind contribution in the literature on stadiums and sport arenas, offering valuable insights into possible factors that influenced the evolution of crowd behavior during large-scale events.

SINGLE-DEGREE-OF-FREEDOM VIBRATION ISOLATION SYSTEM WITH ONE ADDITIONAL SUPPORT

Vibration isolation is one of the most effective methods for reducing vibration levels of supporting structures when installing vibroactive equipment (active vibration isolation) or vibration levels of vibro-sensitive objects relative to foundation vibration levels (passive vibration isolation). Damping devices utilizing high-speed fluid flow through apertures have found wide applications in shock vibration isolation and vibration isolation systems in aerospace and defense sectors. Recent research has led to the development of viscous fluid dampers (VFDs) for use in civil engineering, particularly in earthquake-prone areas. Scientists conducted experiments aimed at determining the ability of viscous fluid dampers to reduce damages and displacements of structures without increasing stresses. Mathematical models have been developed and are applied in vibration isolation systems. When vibroactive equipment is installed on building and structure support systems, vibrations with sufficiently high vibration parameters may occur, potentially leading to loss of load-bearing capacity. In such cases, vibration isolation is considered one of the most effective methods for reducing these vibration levels. In this study, a calculation method has been developed, and calculation dependencies and algorithms for calculating vibration protection systems with nonlinear characteristics (additional support connections, viscous fluid damper) have been derived for both single-degree-of-freedom and two-degree-of-freedom systems. The research involved an analysis of normative and scientific-technical literature on the subject: types, structural solutions, calculation, and analysis of vibration protection systems. The main method selected was based on the use of transfer functions of linear systems (the non-traditional "normal form" method). Calculations were performed using computer mathematics systems- Matlab.

SCIENTIFIC APPROACHES TO THE DEVELOPMENT OF COMPOSITES MATERIALS FOR REDUCING VIBRATION AND NOISE IN PRODUCTION

Goal. Scientific approaches to the development of composite materials for noise and vibration reduction in the workplace and evaluation of their effectiveness. Methodology. Сomplex of scientific methods for assessing the impact of environmental factors, such as noise and vibration, on the worker was used for the research. Сomparative evaluation of the effectiveness of the developed composite materials with the existing ones was carried out in terms of their ability to reduce noise and vibration at the worker's workplace. Results. New composite materials with an extended spectrum of action have been developed. Their effectiveness in laboratory and production conditions was evaluated. Their effectiveness was evaluated at those workplaces where an increased level of noise and vibration is registered, a comparative analysis of the new vibration-absorbing materials developed by the authors with those existing in laboratory and production conditions was carried out.Conducted studies have shown that «Vibroshtil» and «Vibroshtilmaxi» vibration-absorbing materials are characterized by a higher level of sound absorption compared to both domestic and materials of the same purpose produced in other countries, and are proposed for implementation in production, railway transport and the subway. Conducted studies have shown that «Vibroshtil» and «Vibroshtilmaxi» vibration-absorbing materials are characterized by the higher level of sound absorption compared to both domestic and materials of the same purpose produced in other countries, and are proposed for implementation in production, railway transport and the subway. The comparative evaluation made it possible to prove the effectiveness of the developed composite vibration-absorbing materials for the correction and reduction of noise and vibration levels in workplaces. The results were achieved due to the optimal selection of ingredients of composite materials and their ratio. Scientific novelty. The effectiveness of new composite materials «Vibrostil» and «Vibrostilmax» for reducing noise and vibration levels at workplaces was developed and evaluated, and their effectiveness was evaluated in order to prevent the risk of workers suffering from vibration sickness. Practical significance. The introduction of developed vibration-absorbing materials will reduce the level of noise and vibration in the workplace and reduce the risk of workers suffering from vibration sickness.

Optimalisasi Isian Bahan Peledak Terhadap Jarak Lokasi Peledakan Dengan Penempatan Alat Dalam Kegiatan Peledakan Di Dekat Low Wall Pit 9 Berdasarkan Nilai Peak Particle Velocity Pada Pt Alamjaya Bara Pratama

Ground vibration is a wave that moves in the ground caused by the presence of an energy source. Ground vibration in detonation is caused by several things, one of which is the excessive use of explosives. Peak Particle Velocity is one of the criteria for determining the level of vibration that affects the Low Wall at the mine site.From ground vibration measurements from 02 – 26 September 2022 an analysis was carried out using the Blastware application. The result of the analysis is the equation for the relationship between PPV and scaled distance (SD), namely PPV = 18268.2 (SD)-1.725 with a data confidence level of 0.787 = 78% which states that the data can be trusted.The relationship formula equation between PPV and SD is then used to determine the maximum explosive charge and the safe distance for blasting activities based on PT. Alamjaya Bara Pratama. ground vibration standards.

Topology optimization framework for thermoelastic multiphase materials under vibration and stress constraints using extended solid isotropic material penalization

This paper proposes a multiphase material topology optimization (MMTO) method for thermal–mechanical structures that takes into account the effect of the temperature field under stress and frequency constraints. Thermoelastic coupling occurs when an engineering structure is concurrently subjected to thermal and mechanical loads. This work focuses on the following: (1) the derivation of three interpolation schemes that use stress, dynamic, and thermal loads based on the extended solid isotropic material penalization (SIMP) method; (2) the incorporation of stress and dynamic constraints of multi-material thermal-elastic structural designs; and (3) the effective control of the impact of thermal loads on structures based on stress and frequency levels. Numerical experiments show that a clear distinction exists in the final topologies for mechanical and thermal loads among materials. Coupled and uncoupled mechanical and thermal behaviors can be predicted using finite element models based on materials’ coefficients of thermal expansion. We see this method is capable of optimizing a structure’s strength and stability while solving the issue of a thermal environment. In addition, it allows for the precise management of stress and vibration levels when structures are not exposed to a thermal environment.

Peculiarities of using small-diameter bored piles for effective solving of geotechnical problems

Abstract. The peculiarities of the use of small-diameter drill piles in modern construction considered, with an emphasis on their advantages and areas of application in specific conditions. Two main types of piles distinguished: cast-in-place, which characterized by continuous reinforcement and filling with concrete or cement mortar, and composite, where the load transfers to reinforcing elements. Main advantages of small-diameter bored piles noted, including the possibility of performing work in confined spaces, reducing the level of noise and vibrations, a variety of drilling technologies, the possibility of application in geological conditions of varying complexity, etc. Particular attention paid to the areas of application of small-diameter bored piles, including the installation of new foundations, underpinning of existing structures, soil improvement and land-slide protection. The main groups of factors that can influence the choice of small-diameter bored piles as the main design decision for various fields of application considered, including: - physical factors (restricted access, remoteness of the area, distance of piles to existing structures); - subsoil factors (difficult geological conditions, soil liquefaction tendency); - environmental factors (sensitivity to vibration/noise, hazardous or contaminated soils); - necessity of adaptation to existing structures; - load/settlement requirements; - economic factors. Limitations for the use of small-diameter drill piles from the point of view of their efficiency described. An example of the effective practical use of small-diameter bored piles in the confined conditions of dense urban development in close proximity of metro tunnels with increased requirements regarding the level of vibrations and noise considered. The task of minimizing subsidence of the designed residential and office complex and the impact on surrounding buildings and structures solved. The compliance of the adopted design decisions confirmed by means of field tests, as well as using the results of settlements monitoring. Attention focused on the need for further improvement of design approaches and technological solutions to optimize the efficiency of small-diameter bored piles for solving geotechnical problems.

Experimental investigation of dynamic features and propagation law of ground vibrations induced by a suspended monorail train

This study focuses on experimental investigation of the dynamic features and propagation law of ground vibrations induced by suspended monorail transportation (SMT), which is rarely reported. First, a comprehensive field measurement of suspended monorail train-induced ground vibrations is performed and the acceleration responses at different measurement positions are obtained. Then, the vertical and lateral vibrational responses are elaborately analysed in the time and frequency domains. The dynamic features and transmission laws of the ground vibrations are revealed, and some interesting phenomena are discovered. Finally, an effective signal post-processing method is adopted to furthest reduce signal truncation errors. The 1/3 octave analysis method is adopted for elaborately evaluating both the ground vibration levels with time and frequency division under different train operating conditions. The research results can provide useful guidance for route selection of SMT and numerical model validation.

Helium screw compressor for 5tpd large-scale hydrogen liquefier

Liquid hydrogen has promising applications in various industries. As an important heart role, compressors are essential for efficient hydrogen liquefaction. This study introduced a novel profile screw compressor employed in large-scale hydrogen liquefaction processes. The development addressed the challenges associated with large-scale rotors, high pressure differences, and demanding capacity or torque requirements. By utilizing a 5/7-lobe combination of male to female rotors, this technology effectively tackled issues related to rotor dynamics, such as heavy-load rotor stiffness and dynamic balance. The profile design followed hydrodynamics principles, reducing viscosity loss and oil–gas flow loss at high speeds, large flow rates, and significant pressure differences. The profile curve’s curvature and geometric configuration were tailored to the specific pressure state during compression. In high-pressure areas, the profile remained relatively flat to maintain machining accuracy. While in low-pressure areas, the curvature was increased, and the meshing clearance was reduced to minimize helium leakage. Experimental tests conducted under conditions similar to actual hydrogen liquefaction processes have successfully validated the theoretical profile design and the newly developed multi-point oil injection cooling technologies. These advancements have led to an impressive isothermal efficiency of 58.1 % for the entire screw set. Furthermore, the stability and reliability of the compressor were verified through noise and vibration signal testing. The results demonstrated that the compressor operated with noise levels below 96 dB (A) and vibration levels below 7 mm/s, further ensured its suitability for large-scale cryogenic applications. These compressors have successfully run stably on the 5.17 tpd (ton per day) hydrogen liquefier. Overall, this research would significantly contribute to the advancement of screw compressors and large-scale cryogenic technology.

Research on unbalanced characteristics of axial-varying eccentric rotor based on signal demodulation

In the presence of non-uniform loads, rotor misalignment emerges as a prevalent fault in permanent magnet synchronous motors (PMSMs), leading to the manifestation of an axial-varying eccentric air–gap. Considering the three-dimensional (3D) nature of magnetic flux under axial-varying eccentric fault, 3D finite element (FE) analysis method was used in this paper. Then, the electromagnetism simulations were conducted to calculate the magnetic flux density and unbalanced magnetic pull (UMP). With the signal demodulation algorithm based on principal component analysis (DPCA), the frequency modulation of various signals from simulation and experiment was extracted. Furthermore, based on the modulation features, the relevance among magnetic flux density, UMP, and vibration acceleration was established with shaft frequency as the link. The coupling of magnetic field and vibration level shown in results was analysis, which provide important theoretical and engineering references for the safe operation of PMSM system and the exact identification of rotor tilting faults.

Exploring the Feasibility of Estimating Intraocular Pressure Using Vibrational Response of the Eye: A Methodological Approach.

This study addresses the limitations of current tonometry techniques by exploring vibroacoustic properties for estimating intraocular pressure (IOP), a key diagnostic parameter for monitoring glaucoma-a significant risk factor for vision loss. Utilizing vivo porcine eyeballs, we investigated the relationship between IOP and the nonlinear vibration transfer function ratio (NVTFR). Through applying varying vibration levels and analyzing responses with transfer function analysis and univariate regression, we identified a strong negative correlation between NVTFR and IOP, evidenced by a Pearson correlation coefficient of -0.8111 and significant results from generalized linear model (GLM) regression (p-value < 0.001). These findings indicate the potential of NVTFR as a vital indicator of IOP changes. Our study highlights the feasibility of using vibroacoustic properties, specifically NVTFR, to measure IOP. While further refinement is necessary for in vivo application, this approach opens new possibilities for non-invasive and patient-friendly IOP monitoring, potentially enhancing ophthalmology diagnostic techniques and providing a foundation for future research and development in this critical area.

Analysis on characteristics of ground vibration induced by underground high-speed trains based on in-situ test

With the increasingly emerging traffic intersection form of high-speed railways passing underneath integrated transport terminals, the ground vibration induced by trains running on underground high-speed railways has attracted extensive attention. In combination with the engineering example of a high-speed railway in construction passing underneath an airport, the wheel-drop impact test in the high-speed railway tunnel was designed to obtain the vibration characteristics of surrounding soil. The vehicle-track-tunnel-ground semi-analytical three-dimensional model was established to determine the initial dynamic load condition of the vehicle loads. The amplitude-frequency characteristic and transmission law of the ground vibration induced by trains running on underground high-speed railways were predicted and analyzed. The influences of different operation conditions, track parameters, and tunnel burial depths were compared. The research results show that the ground vibration obtained through the wheel-drop test is greatly attenuated within 10 m from the track centerline, with an attenuation rate up to 70%. The vertical vibration amplitude is obviously larger than that of the other two directions. The lateral ground vibration amplitude is the smallest with the slowest vibration attenuation speed. When the high-speed train passes through at the speed of 350 km/h, the vertical and lateral vibration levels of the ground surface within 80 m range are 20∼80 dB and 43∼72 dB, respectively. The maximum attenuation coefficient of Z-vibration level reaches 0.276 dB/m. For each increase of 50 km/h of the train speed, the Z-vibration level of the ground increases by about 2 dB. The smaller fastener stiffness leads to the greater ground vibration within 20∼50 Hz. The ground vibration level is positively correlated with the fastener stiffness above 79 Hz. When the burial depth of the tunnel is greater than 14 m, the burial depth of the tunnel has little effect on the change of the Z-vibration level of the ground.

Manikin study showed that neonates are exposed to high sound and vibration levels during helicopter incubator transports.

This initial Norwegian study aimed to quantify the vibrations and sounds experienced by neonates when they were transported by helicopter in an incubator. Two neonatal manikins weighing 500 and 2000 g were placed in a transport incubator and transported in an Airbus H145 D3 helicopter during standard flight profiles. The vibrations were measured on the mattress inside the incubator and the sound levels were measured inside and outside the incubator. The highest vibration levels were recorded during standard flight profiles when the lighter manikin was used. These ranged 0.27-0.94 m/s2, compared to 0.27-0.76 m/s2 for the heavier manikin. The measurements exceeded the action levels set by the European Union Vibration Directive for adult work environments. The sound levels inside the incubator ranged 84.6-86.3 A-weighted decibels, with a C-weighted peak level of 122 decibels. The sound levels inside the incubator were approximately 10 decibels lower than outside, but amplification was observed in the incubator at frequencies below 160 Hz. Vibrations were highest for the lighter manikin. The sound levels during helicopter transport were higher than recommended for neonatal environments and sounds were amplified within the incubator at lower frequencies.

Track–bridge interaction effects in the acceleration and displacement response of high-speed railway bridges: Simplified vs refined modelling

The prediction of structural vibrations induced by high-speed trains is crucial for designing bridge structures, as well as for the assessment of the dynamic compatibility between bridges and rolling stock in large railway networks. The computational effort involved in such dynamic compatibility checks is also large. However, obtaining an accurate prediction of the dynamic response is challenging due to numerous uncertain factors still under research. Interaction phenomena like vehicle–bridge (VBI), soil–structure (SSI), and track–bridge (TBI) interactions are crucial but complex to model, given the multitude of input parameters and the computational cost required. Therefore, the choice of a modelling approach for simulating the dynamic response of a train crossing a bridge will depend on the focus of analysis. For the purpose of sensitivity analyses – typical in early design stages –, compatibility checks (screenings), and also in non-deterministic analyses, computational cost becomes crucial. Consequently, for practical purposes interaction mechanisms are often simulated by means of simplified and conservative approaches, usually aligned with some design code recommendations. Moreover, traditional physical models, where the problem is idealised as a beam traversed by constant moving loads (travelling load model, TLM), have been commonly employed for such purposes. However, they neglect the load distributive effect of the track on the vehicle axle loads, which has proven to be relevant and beneficial, especially for short bridge spans. The main purpose of this work is thus to investigate the influence of the load spreading effect exerted by the ballasted track on the displacement and acceleration response of single-track, simply-supported (S-S) railway bridges of short-to-medium span lengths under operating conditions, since these structures are prone to experience inadmissible vibration levels under more demanding traffic conditions. A comprehensive analysis of several simplified approaches proposed by regulations and researchers is performed, plus a subsequent comparison vs. a finite element (FE) strategy to consider TBI in a refined manner. Conclusions about the adequacy of the simplified approaches are provided, along with a new data-driven formula for the prediction of the vertical displacement response in resonant conditions, that can be exploited to reduce significantly the computational effort.

SUBSTANTIATION OF CHANGES IN THE CERTIFICATION OF THE TRACTOR DRIVER’S WORKPLACE IN MODERN MACHINE-TRACTOR UNITS

The study aims to identify possible changes in the working conditions of tractor drivers under the computerisation of workplaces and to develop proposals for changing the requirements for sanitary standards in the design of tractors and agricultural machinery. The article analyses the impact of modern technologies on the working conditions of tractor drivers in agriculture. It investigates various aspects of work, including using on-board computers, air conditioning, and satellite navigation, and their impact on workers’ health. The authors consider health risks, such as increased noise levels and work with on-board computers, and reveal the lack of consideration of these aspects in regulatory documents. In particular, we have found that using on-board computers significantly simplifies the process of controlling agricultural machinery but can lead to increased noise and vibration levels, negatively affecting workers’ health. Some studies have shown that prolonged work with on-board computers can lead to the development of occupational diseases, such as musculoskeletal disorders, impaired vision, and others. In addition, air conditioning in tractor cabs can cause colds due to sudden temperature changes and increase the risk of legionella infection due to the water condensation accumulation in ventilation systems. The research also found that the legal and regulatory documents governing the working conditions of tractor drivers do not consider the use of modern technologies, which creates gaps in worker protection. Regulatory documents should contain requirements for the parameters of monitors and their placement in the working area of tractor drivers in agricultural production, such as adjusting the reflectivity of the screen, the main adjusted visual characteristics of monitors, and the location of video terminals in the tractor cab without being directly in the line of sight. It is necessary to develop measures to prevent the overwork of tractor drivers. Regulations should include rules for the use of air conditioners, as well as for cleaning air conditioning ducts and replacing filters on time. The general conclusion is that there is a need to strengthen the regulation of tractor drivers’ working conditions and to include requirements for using modern technologies in the relevant regulations. These measures will ensure the safety and health of workers in agriculture and reduce the risk of occupational diseases. Keywords: machine-tractor unit, tractor driver, workplace certification, labour protection, video terminal.

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This article addresses the bifurcation characteristics and vibration reduction of a 2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2$$\\end{document}-DOF dynamical system simulating the nonlinear oscillation of an asymmetric rotor model subjected to simultaneous multiparametric and external excitations. To suppress the system's vibrations, two 1/2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1/2$$\\end{document}-DOF active dampers are attached to the system in linear and cubic nonlinear forms via a magnetic coupling actuator. The closed-loop system model is derived as two differential equations with multi-control terms, including cubic, quantic, and septic, coupled nonlinearly to two first-order systems. Applying perturbation theory, the system model is solved, and the autonomous system describing the closed-loop slow-flow dynamics is obtained. Through numerical algorithms, the motion bifurcation is analyzed using various tools such as 2D and 3D bifurcation diagrams, two-parameter stability charts, basins of attraction, orbit plots, and time response profiles. The analytical investigations confirm that the uncontrolled model behaves like a hardening Duffing oscillator with multistability characteristics, displaying simultaneous mono-stable, bi-stable, tri-stable, or quadri-stable periodic oscillations depending on both the asymmetric nonlinearities and angular velocity. Subsequently, the influence of different control parameters is analyzed to determine the threshold between mono and multi-stability conditions. Finally, optimal control parameters are designed to eliminate multistability characteristics and achieve minimum and safe vibration levels.

Design and Implementation of Water PH Level and Turbidity Monitoring System

Abstract: Building collapses have become a distressing and recurring issue in Nigeria, necessitating urgent action to mitigate their occurrence. This paper introduces an innovative approach to address this challenge by developing an Automated Structural Health Monitoring System (ASHMS) utilizing a mobile app. Focusing on major cities like Lagos and Abuja, the proposed system employs strategically placed sensors to gather data from various structural elements of buildings. The collected information, encompassing seismic activity, vibrations, bending moments, shear forces, and other key parameters, is wirelessly transmitted to the cloud where it can then be accessed and visualized using mobile app. The system offers real-time insights into the structural integrity of buildings and provides early warnings, thereby contributing significantly to reducing the risk of building collapses. Key findings show that when incorporated into an automated Structural Health Monitoring (SHM) system, the user's mobile app offers essential structural insights, capturing values such as a 0.5-unit vibration level, 20 units of shear force, 50 units of bending moment, and an 89-degree vertical wall angle. The app's userfriendly interface improves the effectiveness of monitoring and overseeing structural health, in line with the overarching objective of promoting safety in construction practices

Automated Structural Health Monitoring System for Mitigating Building Collapse in Nigeria: A Mobile App Approach

Abstract: Building collapses have become a distressing and recurring issue in Nigeria, necessitating urgent action to mitigate their occurrence. This paper introduces an innovative approach to address this challenge by developing an Automated Structural Health Monitoring System (ASHMS) utilizing a mobile app. Focusing on major cities like Lagos and Abuja, the proposed system employs strategically placed sensors to gather data from various structural elements of buildings. The collected information, encompassing seismic activity, vibrations, bending moments, shear forces, and other key parameters, is wirelessly transmitted to the cloud where it can then be accessed and visualized using mobile app. The system offers real-time insights into the structural integrity of buildings and provides early warnings, thereby contributing significantly to reducing the risk of building collapses. Key findings show that when incorporated into an automated Structural Health Monitoring (SHM) system, the user's mobile app offers essential structural insights, capturing values such as a 0.5-unit vibration level, 20 units of shear force, 50 units of bending moment, and an 89-degree vertical wall angle. The app's userfriendly interface improves the effectiveness of monitoring and overseeing structural health, in line with the overarching objective of promoting safety in construction practices.

Dynamic response of a pipe with geometrical restriction subjected to gas-liquid internal flow

Due to the potential hazard of deepwater oil exploration, the Brazilian industry has an ever-increasing concern for reliability during hydrocarbon production. A major source of concern is mechanical failure in devices, such as safety valves, which can fail without warning, putting both the operation and the environment at risk. A possible reason for malfunction and failure could be the permanent occurrence of vibrations induced by internal two-phase flow during the extraction of fluids from the well. An experimental campaign is proposed to better understand these phenomena. Twenty two-phase flow conditions were tested, with superficial velocities ranging from 0.1 m/s to 2.0 m/s for water, and 0.33 m/s to 7.47 m/s for compressed air. The experiments were carried out in a restricted pipe and a pipe without any restriction to evaluate and compare the vibrations produced by two-phase flow (2-FIV). Three accelerometers positioned downstream of the restriction were used to collect vibrational amplitude spectral density data, 2-D acceleration magnitudes, and RMS values of acceleration. Among the main findings are the roles played by the gas volumetric fraction and the mixture velocity, which strongly influence the vibrational amplitude of both tubes, and the observation that the gas phase is the main responsible for vibrational amplitudes at low frequencies, while the liquid phase acts mainly at high frequencies. Furthermore, the flow pattern is also considered a key feature in determining the vibration level, as 20- and 12-fold increments have been observed for the same volumetric fraction when comparing elongated bubbles and severe slug patterns. Finally, it was demonstrated that the presence of an internal restriction strongly influences the structural response.