Acceleration Measurements Research Articles

Degree of corrosion and other deterioration effects in highway bridge deck component using non-destructive self potential and vibration testing: case study from SW Nigeria

Recently, the corrosion of steel reinforcement and high vibration intensity have become a major problem in highway bridge stability analysis, and structures that involved reinforcing steel. Therefore, based on suspected human perception, the Ogbese highway bridge stability was investigated using non-destructive half-cell method and vibration measurement. The half-cell measurement was taken at 1 × 1 m grid using Cu/CuSO4 half-cell standard reference electrode, while vibration measurement was taken using vibration meter. The meter is capable of switching acceleration measurement between high (1–4 kHz) and low frequency (10 Hz to 1 kHz) with measurement accuracy of ± 10. The SP result showed that areas with Ecorr greater than −200 mV is 90.8%, Ecorr of −350 mV ≤ Ecorr ≤ −200 mV accounts for 8.5%, and areas with Ecorr less than −350 represents 0.7%. Consequently, the bridge deck is still safe at present. The anomalous zones are represented in each of the bridge span, and mostly within the location of the piers. This implies that there are contributions from the piers/piles reinforcements’ activity. The bridge is also characterized by varying vibration intensity, very high at the northeastern part in terms of acceleration, and displacement than at the southwestern, and middle parts. This is also supported by comparative wide range of values obtained at northeastern part—acceleration, and displacement for the vibration intensities. However, the increasing corrosion activity presently going on may undermine its stability in the long run. Hence a need for thorough maintenance and assessment from time to time.

ОБЗОР МЕЖДУНАРОДНЫХ КАЛИБРОВОЧНЫХ СИСТЕМ И ИХ РОЛЬ В ЭКОЛОГИЧЕСКИХ ИССЛЕДОВАНИЯХ

The article provides examples of the use of gravimetric observations to monitor the environmental situation of mineral deposits. Such measurements are usually made by a group of devices. A high level of accuracy requires the consistency of all instruments used, which is achieved by calibration. An overview of gravimetric calibration systems, which play a key role in accurate and reliable measurement of gravity acceleration on the Earth’s surface, is given. Calibration bases are necessary to ensure metrological control and improve measurement accuracy in such fields of Earth sciences as geodesy, geophysics, geology and other related disciplines. This article discusses different gauge systems used in different countries, including Russia, Poland, Croatia, Switzerland, Canada, Austria, Germany, China, Estonia, Finland, Iran, Brazil, and also in the Republic of Kazakhstan.

Development and validation of inverted head form orientation for helmet testing using a pneumatic linear impact system

Despite growing public health awareness of concussions and their cognitive sequelae, research has predominantly focused on generic bulk-head form impact metrics rather than the study of how brain tissue responds to head impacts. In this paper, the authors develop and validate a novel testing fixture that can configure standard head forms in an inverted orientation, with the future goal of testing inverted cadaveric specimens with gravity-driven perfusion of the head. The inverted testing fixture was integrated with an existing pneumatic linear impactor system and suspended a Hybrid III instrumented head and neck form on an x–y linear sliding carriage. Validation studies compared impacts in upright and inverted orientations, with and without a football helmet, at 5.5 and 7.4 m/s. Angular velocity and linear acceleration measures were found to be similar. The results support the use of the novel fixture for studying inverted cadaveric specimens during simulated concussive impacts.

Leisure-Time Physical Activity, Sedentary Behavior, and Biological Aging: Evidence From Genetic Correlation and Mendelian Randomization Analyses.

Physical inactivity and sedentary behavior are associated with higher risks of age-related morbidity and mortality. However, whether they causally contribute to accelerating biological aging has not been fully elucidated. Utilizing the largest available genome-wide association study (GWAS) summary data, we implemented a comprehensive analytical framework to investigate the associations between genetically predicted moderate-to-vigorous leisure-time physical activity (MVPA), leisure screen time (LST), and four epigenetic age acceleration (EAA) measures: HannumAgeAccel, intrinsic HorvathAgeAccel, PhenoAgeAccel, and GrimAgeAccel. Shared genetic backgrounds across these traits were quantified through genetic correlation analysis. Overall and independent associations were assessed through univariable and multivariable Mendelian randomization (MR). A recently developed tissue-partitioned MR approach was further adopted to explore potential tissue-specific pathways that contribute to the observed associations. Among the four EAA measures investigated, consistent results were identified for PhenoAgeAccel and GrimAgeAccel. These two measures were negatively genetically correlated with MVPA (rg = -0.18 to -0.29) and positively genetically correlated with LST (rg = 0.22-0.37). Univariable MR yielded a robust effect of genetically predicted LST on GrimAgeAccel (βIVW = 0.69, p = 1.10 × 10-7), while genetically predicted MVPA (βIVW = -1.02, p = 1.50 × 10-2) and LST (βIVW = 0.37, p = 1.90 × 10-2) showed marginal effects on PhenoAgeAccel. Multivariable MR suggested an independent association between genetically predicted LST and GrimAgeAccel after accounting for MVPA and other important confounders. Tissue-partitioned MR suggested skeletal muscle tissue associated variants to be predominantly responsible for driving the effect of LST on GrimAgeAccel. Findings support sedentary lifestyles as a modifiable risk factor in accelerating epigenetic aging, emphasizing the need for preventive strategies to reduce sedentary screen time for healthy aging.

Alignment of Fabry–Pérot Cavities for Optomechanical Acceleration Measurements

The wave optics processes in a Fabry–Pérot cavity with a length of about tens of millimeters are considered. Such cavities are used, among other applications, in optomechanical accelerometers for precise measurement of displacement of moving elements. A Fabry–Pérot cavity formed by a spherical and flat mirror is considered. The influence of parameters characterizing the alignment of the Fabry–Pérot cavity mirrors and the laser beam on the appearance of the higher order modes is investigated using numerical modeling. It is shown that the angle of inclination of the flat mirror of the cavity greatly affects the occurrence of higher order modes in addition to the fundamental mode. The levels of displacement of the axis of a spherical mirror in the vertical direction which do not cause the emergence of higher order modes is shown. The influence of the degree of displacement of the laser beam axis in the vertical direction relative to the symmetry axis of the Fabry–Pérot cavity is also investigated.

Prototype component test series "Ultrasonic Surface Rough Meter" (Accelerometer Test Series)

Based on Government policies that continue to encourage increased use of domestic products (P3DN) and enlarge the level of domestic components (TKDN) to realize the independence of the domestic industrial sector, we are trying to make an instrument that will be implemented to determine the level of road damage, with accelerometers, ultrasonic sensors and GPS which become a unit in the instrument that we will make under the name "Ultrasonic Surface Rough meter". To find out the success of the prototype product "Ultrasonic Surface Rough meter" carried out various tests and one of them was the prototype component test "Ultrasonic Surface Rough meter" which consisted of ultrasonic sensor component tests, accelerometer component tests, and Global Positioning System (GPS) tests and here only focused on ultrasonic sensor tests, The results of acceleration measurements using the prototype "Ultrasonic Surface Rough meter" carried out by statistical analysis on all tests using accelerometers on the prototype "Ultrasonic Surface Rough meter" can be said to be "Valid and correct".

Correlation between perinatal abnormalities and decreased fetal movement as counted by a fetal movement acceleration measurement recorder: A prospective cohort study.

The objective was to study the relationship between a decrease in gross fetal movement during maternal night sleep counted by an objective method and abnormal perinatal outcomes. This was a prospective cohort study. A total of 470 pregnant women recorded fetal movement with the fetal movement acceleration measurement recorder weekly after 28 weeks. The ratio of 10-s epochs with fetal movement to all epochs was calculated as the fetal movement parameter. When the parameter was below the 10th percentile of the previously made reference curve, it was defined as decreased movement. Women who showed a decreased movement at least once were classified into a study group, and the other women were classified into a control group. Abnormal perinatal outcomes between the two groups were compared with the Chi-square test. There were more preterm births (19%) in the study group than in the control group (10%) (P = 0.0210). There was a significant difference for iatrogenic preterm birth (P = 0.0241) but not for spontaneous preterm birth (P = 0.4566). There were more hypertensive disorders of pregnancy (11.6%), small-for-gestational-age newborns (10.7%), and Apgar scores below 7 points at 1 min (7.4%) in the study group than in the control group (5.2%, 4.8%, and 2.6%, respectively) (P = 0.0329, 0.0459, and 0.0487, respectively). A decrease in gross fetal movement during maternal night sleep was related to iatrogenic preterm births, small-for-gestational-age newborns, hypertensive disorders of pregnancy, and low Apgar scores at 1 min.

History of height reference systems in the territory of the Republic of Serbia

The Republic of Serbia inherited two unique reference height systems. The first, the Precise levelling of the Austro-Hungarian Monarchy (APL), was a significant undertaking by the Military Geographical Institute from Vienna between 1874 and 1905. The reference surface of the APL, the mean sea level, was determined in Trieste based on a year of tide gauge measurements in 1875. This system, which remained used in Serbia and later in Yugoslavia until 1999, was replaced by the Second High Precision Levelling Network of Yugoslavia, carried out by domestic geodetic service between 1970 and 1973, and the mean sea level was determined based on five tide gauges, epoch 1971,5. Notably, during the execution of levelling measurements no measurements of gravitational acceleration were taken along the levelling lines. As a result, the heights were and continue to be expressed in the normal orthometric (spheroidal) height system, a practice that has endured to this day. This paper meticulously chronicles the most significant stages and characteristics in establishing reference height systems in Serbia's territory.

Distributed cooperative guidance law without numerical singularity with field-of-view angle constraint

Abstract A distributed cooperative guidance law without numerical singularities is proposed for the simultaneous attack a stationary target by multiple vehicles with field-of-view constraints. Firstly, the vehicle engagement motion model is transformed into a multi-agent model. Then, based on the state-constrained consensus protocol, a coordination control law with field-of-view (FOV) constraints is proposed. Finally, the cooperative guidance law has been improved to make it more suitable for practical application. Numerical simulations verified the effectiveness and robustness of the proposed guidance law in the presence of acceleration saturation, communication delays and measurement noise.

Dynamic response and vibration signature assessment of SDOF steel system using RISAM shaking table

Civil engineering structures face major challenges, particularly earthquakes, which are random phenomena in their intensity and frequency content. The seismic response of structures depends largely on the intensity of an earthquake and especially on its frequency content. Structural Health Monitoring (SHM) is a relevant tool for assessing the dynamic behavior of structures subjected to seismic excitations. This is achieved by using experimental measurements of structural dynamic parameters. The main objective of this study is to identify the vibration signature of a single-degree-of-freedom SDOF steel system. Based on the laws of similarity, a 1:6 reduced-scale model is developed. In this context, dynamic experiments using the shaking table of the RISAM laboratory (Risk Assessment and Management: University of Tlemcen) are carried out to determine the structural dynamic parameters of this steel system. This is achieved through experimental determination of natural frequency and damping of the reduced model. Acceleration and displacement measurements are also established. The experimental estimation of damping is established using the logarithmic decrement method. Several dynamic analyses are carried out based on the finite elements model of the reduced steel system model. The obtained results show that the approach used to determine the dynamic parameters of this reduced model leads to realistic results. On the other hand, a perfect concordance between the numerical and experimental results has been approved.

Application of Nonlinear Optimization in Flight Path Reconstruction of a Sub-scale Aircraft

One key challenge in working with free-flight test data is ensuring its compatibility with the dynamic systems of sub-scale unmanned aircraft. This is crucial to avoid errors in measurements, bias, or scaling issues that could compromise the integrity of the estimated results. We refer to this initial processing step as data compatibility checking, a rigorous process that forms the foundation of our research.Typically, this verification process involves flight path data reconstruction (FPR) predicated on estimating the aircraft’s flight kinematics. The predominant methodologies encompass the stochastic approach, the Extended Kalman Filter (EKF), and the deterministic approach, employing the Output Error Method (OEM). In this research, we propose to approach the problem from the perspective of a nonlinear optimizer to estimate the reconstruction of data derived from free-flight tests of a sub-scale aircraft.The nonlinear optimizer we employ in this research was designed to verify the authenticity of the data representing the aircraft's actual flight. It does this by comparing the measurements of attitude angles, accelerations, and velocities with the expected kinematic behavior of the aircraft. This rigorous evaluation process ensures that the reconstructed data is as close to the actual flight as possible, enhancing the reliability of our results.The sub-scale model deployed in these tests was engineered to emulate the dynamic characteristics of a full-scale aircraft, utilizing the Froude number criterion for appropriate scaling. The chosen aircraft for this project was a Cessna 177B, and the sub-scale aircraft was developed by the Aeronautical Systems Laboratory (LSA) at the Aeronautics Institute of Technology (ITA).This study will delineate the outcomes achieved through FPA employing OEM techniques and compare these results with the studies derived from the proposed nonlinear estimation method.

Model for Determining Earth's Gravitational Acceleration on a Mathematical Pendulum

Gravity is an accelerating property of the earth that causes objects to fall freely. The acceleration of gravity is not the same at every place on the Earth's surface. To measure the Earth's gravity (small g), scientists can use various techniques, such as dropping a mass from a certain height and measuring the time it takes to fall to the ground or using a mathematical pendulum to measure the period of oscillation and use it to calculate the acceleration due to gravity. In this paper, a study of the mathematical pendulum in the measurement of the Earth's gravitational acceleration is conducted, and the measurement experiment is illustrated. Method To measure the length of the pendulum, you must have a ruler, meter stick, or tape measure. At the top end of the string, start the measurement at the point where the string rotates out of place. Then, measure up to the center of the pendulum, which is the object hanging on the string. From the results of this study, it can be concluded that the value of the period of a pendulum is affected by several factors, including the length of the rope used and the angle of initial deviation, while the factors that do not affect the period are the mass and diameter of the pendulum.

Analysis and Decoupling Study of the Coupling Effects on Projectile Acceleration Parameters

Abstract Internal ballistic parameter testing is crucial for evaluating artillery performance and design, with projectile acceleration being a core parameter. During the firing process, projectile acceleration parameters can easily be coupled with the projectile’s modal effects and the transverse effects of triaxial accelerometers, leading to inaccurate measurements. Therefore, this paper innovatively proposes a data decoupling method to improve the accuracy of acceleration measurements. Firstly, the internal ballistic firing mechanism and the transverse effects of triaxial accelerometers are analyzed. Secondly, a simulation analysis of the projectile modal is conducted, combined with the projectile’s motion state within the barrel, to determine the modal orders and frequencies under axial stretching and compression vibration modes. Thirdly, shock tests are performed on triaxial accelerometers using a shock table to establish the relationships between triaxial acceleration signals. Finally, the projectile modal, Empirical Mode Decomposition (EMD), and the transverse effects of triaxial accelerometers are combined to decouple the acceleration signals. A comparison between the decoupled acceleration signals and theoretical data shows that the error is reduced from 8.1% to 3.2%, significantly improving the accuracy of the acceleration signals.

Study on the Dynamic Response of the Hull Beam Model under the Combined Action of Wave Loading and Impact Loading

Abstract This paper aims to conduct experimental research on the dynamic response of hull structures under the combined action of wave loads and impact loads. Using an equivalent hull girder model as the research object, multiple sets of regular wave and impact load physical model tests were carried out. The test results show that under the combined action of wave-impact loads, the acceleration measurement points on the hull girder are mainly dominated by the dynamic response caused by the impact load at the moment of impact load application. Subsequently, within the wave period, the dynamic response caused by the impact load gradually decreases, eventually returning to the dynamic response mainly caused by the wave load. A simplified theoretical model of the hull girder was established, and the accuracy of the simplified theoretical model of the hull girder was verified by comparing the test results. The differential equations of the hull girder under the combined action of simplified wave loads and weak impact loads were established, and the accuracy of the simplified theoretical model of the hull girder was verified by comparing the test results. The research shows that under the combined action of wave-impact loads, the dynamic response of the hull structure cannot be simply superimposed by treating the dynamic responses of the two loads separately.

Measurement of Acceleration Due to Gravity Using Arduino

The undertaken research paper is an easy experiment based on Arduino was constructed in order to investigate the acceleration of the object while it was falling freely and to estimate the value of "g" (the acceleration that is generated by gravity). The reseach aimed to achieve three objectives through this research: first, to comprehend the manner in which airborne gravity gradiometers synthesise gravity fields using residual terrain modelling and the equivalent source layer method; second, to evaluate the durability of systems based on Arduino in various environments; and third, to contrast the accuracy, efficiency, and user-friendliness of these systems with those that are more conventional. The investigation of the acceleration due to gravity measurement using Arduino was conducted using secondary sources, which include books, websites, academic papers, newspapers, and magazines. These sources are not directly comparable. The evaluation and severity determination of a diverse array of research topics are facilitated by this explanatory research approach to the analysis of the conceptual components. The result of the study implies that in order to obtain distance time curves, readings realted to gravity is made at a variety of intervals throughout the course of application of the traditional kinematic equations made it possible to compute the acceleration that happened during the free fall. There has been found to be a good agreement between “the shape of the distance-time graphs” that were gathered from the secondary setup and the graphs that were expected, and the values of g that were calculated were within the range that was anticipated. It has been further discovered that the magnitude of gravitational acceleration is 9.805 metres per second squared after a series of research study were carried out.

A broken-track association method for robust multi-target tracking adopting multi-view Doppler measurement information

Due to reasons such as target maneuvering and track crossing, mistaken track association may be caused. When the target is in Doppler blind zone, it often leads to the loss of measurement information, which is reflected in the situation as track breakage. In response to the demand of track repair in the case of track breakage, we propose a robust multi-target broken-track association method that comprehensively utilizes multi-view Doppler measurement information. Firstly, based on the derivation of measurement coordinate transformation bias, the multi-sensor Doppler measurement after error correction is fused to obtain the heading velocity and heading acceleration measurement of the target. Secondly, the multi-scan association cost function based on the heading velocity and heading acceleration measurement is constructed, and the optimal correlation sequence is obtained by minimizing the complexity of the cost function. Then, for the case of missing measurements, the optimal association sequence is used to extrapolate the missing measurements, thereby accomplishing the correlation among the broken track segment, the extrapolated measurement and the optimal correlation sequence. Thirdly, we design a multi-scan GLMB smoother to perform forward prediction and backward smoothing on the above correlation results to improve the smoothness of the track. Simulation and actual experimental results suggest that our proposed method can effectively deal with the track breakage situation of dense targets, particularly in track integrity, track accuracy and robustness compared with the existing approaches.

Experimental investigation of vortex rope mitigation in a 10 MW axial turbine

Increased utilization of hydraulic turbines as a regulatory tool for electrical grid stabilization forces some turbines to operate away from their design point, thus increasing wear and tear. In here, rotating vortex rope (RVR) mitigation by means of radial insertion of cylindrical rods in the draft tube is investigated experimentally on a 10 MW Kaplan turbine operating as a propeller. Pressure measurements in the draft tube, runner chamber and spiral casing, along with strain and acceleration measurements on the turbine shaft are performed to scrutinize the effectiveness of the mitigation system. Three part-load operating points are investigated, corresponding to 83 %, 72 %, and 68 % of the guide vane servo stroke relative to the best-efficiency point opening. It is shown that the mitigation system dampens the harmful effects of the vortex rope at all operating points, especially at lower part-load conditions. Specifically, the pressure amplitude of the RVR fundamental mode inside the runner chamber reduces by 84 %, 63 %, and 73 % at the three investigated operating points, relative to the amplitudes without mitigation. On the turbine shaft, the fundamental mode of the axial thrust oscillations at the RVR frequency reduces by 65 %, 83 %, and 95 %. It is shown that the mitigation does not come with a high cost on the turbine time-averaged efficiency over the course of the measurements, the penalty being 2 %, 2.5 %, and 3.2 % at the protrusion length where optimal mitigation is achieved at each operating point. For high-head machines, the penalty is expected to be lower since the relative importance of the draft tube diminishes for higher heads.

Transparency-enhanced observer-based adaptive backstepping torque–position control for teleoperation systems with position error constraint and time-varying delay

Nonlinear teleoperation systems are susceptible to significant problems, including transparency, safety, stability and external torques/forces measurement. In order to deal with these limitations, an observer-based adaptive backstepping torque–position control approach is proposed in this paper. In order to achieve this objective, a novel external torque observer is proposed to alleviate the limitations associated with the use of force sensors. This paper’s main idea is to employ a three-channel architecture using a force sensor-less reflecting signal, which can improve transparency and increase algorithm performance. Furthermore, the another point of this paper is to enhance the safeness of operations in the presence of time-varying delays in the communication channel, a position error constraint control strategy is employed in the core of the proposed approach. Moreover, the primary advantage of this paper is that, the proposed observer-based control algorithm is relieved from the joints acceleration measurement of the leader and follower manipulators which is difficult in robotic systems. Finally, the stability analysis of the controller and observer together is conducted by the Barrier Lyapunov functional and series of simulations, comparisons and practical experiments are performed to validate the performance of the proposed algorithm.

Study of the Gearbox Meshing Coupling Vibration Law Based on Mechanical Signal and Frequency Signal

In this study, the failure of a certain type of gearbox of a high-speed locomotive group with cracks is examined, and a gearbox failure assessment method that considers the coupled vibration is established and combined with mechanical signal and frequency signal to determine the basis for judging the failure of a faulty gearbox. First, according to the mechanical model of the finite element calculation, we determined the stress weak links and then the layout response stress measurement points and acceleration measurement points. We then calculated the gearbox ratio, meshing frequency, vibration frequency, mechanical response, modal response, and other frequency characteristics using the Hilbert–Huang transform (HHT) method and the fast Fourier transform (FFT) algorithm to analyze the vibration signals generated by different speeds and wheel out-of-roundness conditions. These were used to calculate the frequency of the different vibration sources of the mechanical response on the weak areas. The frequency correlations of the different vibration sources on the mechanical response in the weak areas were then analyzed, and the vibration transmission law of the gearbox case was obtained. The fault determination criterion was then determined, and the final cause of the fault was obtained.

Assessment of Hoisting Conveyance Guiding Forces Based on Field Acceleration Measurements and Numerical Simulation

Shafts play a key role in the operation of mining plants. They connect underground excavations with the surface and provide the ability to transport people, equipment, and raw materials. The nature of the dynamic interaction of a conveyance moving at a significant speed along deformed guide rails is complex, and the method of assessing the interaction of hoisting conveyances with shaft steelwork, despite ongoing research, still requires further understanding and improvement. Misalignments of the guide rails and conveyance movements transverse to the shaft axis induce impact (guiding) forces, which are the key design parameters of shaft steelwork. The reliable assessment of guiding forces allows the design of safe and economical steelworks and the assessment of their structural safety during operation under deformations and corrosive deterioration. Determining the value of guiding forces requires their field measurements or the use of approximate empirical formulas. Both methods have their limitations—measurement is expensive and interferes with normal shaft operation, while empirical formulas are subject to high error due to the lack of consideration of many structural details specific to each shaft that significantly affect the behavior of the system. This study presents a new method for using a relatively simple-to-implement measurement of hoisting conveyance acceleration to assess guiding forces. A finite element model of the skip and steelwork was built, and simulations of the conveyance interaction with the structure were carried out. A strong relationship between the sliding plate’s impact point location and the guiding force was found. Extreme values of the guiding force were observed in the vicinity of the bunton connection. The study showed that reducing the skip load mass does not affect the force value. Simplified methods of calculating the moments of inertia of the hoisting conveyance significantly overestimate the code-based values of the guiding forces. The presented method considers the actual stiffness and mass distribution of hoisting conveyance and, therefore, allows for a more accurate estimation of the guiding forces and the transport of larger loads. This data-driven approach allows for the continuous monitoring of the guiding forces, the adjustments of the hoisting parameters, the rational planning of repairs, and a reduction in the replacement of corroded shaft steelwork.