Integrating acceleration signal processing and image segmentation for condition assessment of asphalt roads

A proactive road maintenance system enables agencies to better allocate resources to manage their road networks. An inventory of the roads’ conditions is an essential component of such maintenance program. This research project proposes a hybrid system to asses the condition of the asphalt roads, which uses a dashboard-mounted smartphone to simultaneously collect the acceleration response of a vehicle and the video footage of the road surface while driving. The system analyzes acceleration data for anomalous events that could indicate a defect. Then the computer vision module of the system applies semantic segmentation in the corresponding frame to the detected anomaly to identify defects. This system demonstrated 84% recall and 88% precision rates in detection of anomalies in two road segments. Despite these promising results, the system can only detect the defects that are passed over and it could miss some defects with small acceleration responses, such as traverse cracks.

Stress-Strain Relationship: Postulated Concept to Understand Genetic Mechanism Associated with a Seismic Event

In this study, we propose the design methodology for monitoring the earthquake and for detecting and tracking micro-seismic changes in the earthquake prediction system. The alert device includes these sensors will be drastically different from current early warnings using the dozens of seismometers network across seismically active regions for measurement of small acceleration signals directly and, as the first, low-noise stage of the instruments measuring low-noise velocity signals. Strain develops over considerable time in the overlying stratum at right angle to the applied shearing (max) stress, obeying the internal friction of the stratum, available seismic energy and law of stress–strain relationship. Using estimated energy (seismic), stress accumulation, the addition or subtraction in the strain rate due to stress developed can be analyzed for a seismic event. This concept may lead to better understanding of stress generation; build up, transfer and final drop. Then we propose a methodology to identify type of data can be used for the spectral analysis in earthquake seismology and what type of instrument can be used for the spectral analysis in for data acquisition.

Analysis of the Deep Sea Mining Pipe Transverse Vibration Characteristics Based on Finite Element Method

This paper analyzes the transverse vibration laws of 5000 m ladder-shaped mining pipe under different towing velocities and accelerations in the ocean, thinking of the pipe as the beam model, discretized based on the FEM. The algorithm is used to solve the problem to obtain the transverse vibration law. The research shows that the mining pipe overall transverse vibration trend decreases first and then increases, the minimum vibration value occurs at 3000 m, and the maximum occurs at the top. Increasing the towing velocity, acceleration, and ore bin weight will increase the transverse vibration value. The vibration intensity produced by the same acceleration in the constant acceleration and deceleration stages is different, and the damping effect after adding the same damping is also different. In the range of 0.01 m/s2–0.1 m/s2, the vibration reduction effect after adding damping in the constant deceleration stage is more significant, and in the range of 0.1 m/s2-0.2 m/s2, the vibration reduction effect after adding damping in the constant acceleration stage is more significant. In the stage of the constant acceleration or deceleration, when adding the same damping, the vibration intensity generated by the large acceleration is still far greater than the vibration intensity generated by the small acceleration, so the mining ship should keep the small acceleration for towing motion.

Resistive and reactive loads’ influences on highly coupled piezoelectric generators for wideband vibrations energy harvesting

One of the main challenges in energy harvesting from ambient vibrations is to find efficient ways to scavenge the energy, not only at the mechanical system resonance but also on a wider frequency band. Instead of tuning the mechanical part of the system, as usually proposed in the state of the art, this article develops extensively the possibility to tune the properties of the harvester using the electrical interface. Due to the progress in materials, piezoelectric harvesters can exhibit relatively high electromechanical coupling: hence, the electrical part can now have a substantial influence on the global parameters of the piezoelectric system. In order to harness the energy efficiently from this kind of generator on a wide frequency band, not only the electrical load’s effect on the harvester’s damping should be tuned but also its effect on the harvester’s stiffness. In this article, we present an analytical analysis of the influences of the resistive and reactive behavior of the electrical interface on highly coupled piezoelectric harvesters. We develop a normalized study of the multiphysics interactions, reducing the number of parameters of the problem to a few physically meaningful variables. The respective influence of each of these variables on the harvesting power has been studied and led us to the optimal electrical damping expression and the influences of the damping and of the coupling on the equivalent admittance of the piezoelectric energy harvester. Finally, we linked these normalized variables with real reactive load expressions, in order to study how a resistive, capacitive, and inductive behavior could affect the global performances of the system. The theoretical analysis and results are supported by experimental tests on a highly coupled piezoelectric system [Formula: see text]. Using an adequate tuning of a RC load at each frequency, the maximum harvested power [Formula: see text] under a small acceleration amplitude of [Formula: see text] is reached over a 14 Hz large frequency band around 105 Hz which has been predicted by the model with less than 5% error.

Influence of stone cutting waste and ground waste clay brick on the hydration and packing density of cement pastes

The present work aims to study the replacement of Portland cement (PC) by stone cutting waste (SW) and ground waste clay brick (BW) in binary and ternary pastes. Thermogravimetry and differential thermal analysis tests were carried out at various ages in order to investigate the development of the cement hydration reactions in the presence of those wastes. The packing density was calculated in accordance with the Compressible Packing Model to understand the physical effect of those wastes. Compressive strength tests were also performed and the results were related to hydration and packing. Considering the substitution levels studied, the results indicated that the use of SW in the binary mixture accelerated the hydration reactions, and the particles packing density and compressive strength were maintained. The use of BW in the binary mixture caused a small acceleration in the hydration reactions and there was an indication of pozzolanic activity, although the compressive strength was reduced in comparison with the reference paste. In the ternary mixture, the combined effect of both wastes resulted in the maintenance of compressive strength for cement replacement content of 30%.

Convection in heated fluid layers subjected to time-periodic horizontal accelerations

A theoretical study is presented of convection in a horizontal fluid layer heated from below or above which is periodically accelerated in its plane. The analysis is based on Galerkin methods as well as on direct numerical simulations of the underlying Boussinesq equations.Shaking in a fixed direction breaks the original isotropy of the layer. At onset of convection and at small acceleration, we find longitudinal rolls, where the roll axis aligns parallel to the acceleration direction. With increasing acceleration amplitude, a shear instability takes over and transverse rolls with the axis perpendicular to the shaking direction nucleate at onset. In the nonlinear regime, the longitudinal rolls become unstable against transverse modulations very close to onset which leads to a kind of domain chaos between patches of symmetry degenerated oblique rolls.In the case of circular shaking, the system is isotropic in the time average sense, however, with a broken chiral symmetry. The onset of convection corresponds to the transverse roll case studied before with the roll axis selected spontaneously. With increasing Rayleigh number, a heteroclinic cycle is observed with the roll changing its orientation periodically in time. At even higher Rayleigh number, this heteroclinic cycle becomes chaotic similarly to the case of the Küppers–Lortz instability.

Enhancing the Sensitivity of a Resonant Accelerometer

This paper presents an investigation on the sensitivity enhancement of a resonant accelerometer by operating it in the nonlinear regime. The accelerometer is excited by a DC load superimposed to an AC harmonic load. The electric load is tuned such that the accelerometer is driven at primary resonance with a softening-type behavior. Upon the application of a small acceleration, the nonlinear resonance frequency of the accelerometer shifts to a smaller value. This frequency shift is used as an indication for the detected acceleration. This shift is much larger compared to the shift of the resonance frequency of the accelerometer when operating in the linear regime. The concept of the nonlinear excitation is demonstrated by simulation on a commercial capacitive accelerometer. A nonlinear single-degree-of-freedom (SDOF) system is used to model the accelerometer. Several results are shown for the effect of the DC and AC voltages on enhancing the sensitivity of the accelerometer.