Surface Deflection Research Articles

Reweighted L1 Minimization for Networkwide Weak Spot Detection from Traffic Speed Deflectometer Measurements

The traffic speed deflectometer (TSD) can collect network-level deflection data in a cost-effective and timely manner. However, an automated feature extraction method is needed to interpret such large amounts of data. Basis pursuit (BP) is one such technique: BP can sparsely decompose TSD measurements over a given basis or set of bases of the signal vector space that can represent a particular signal feature. For instance, the TSD surface deflection estimates can be reconstructed as a combination of wavelets, which represent continuously varying features like changes in pavement properties, plus pulses representing the response from structurally weak spots. Yet, the denoised measurements estimated by BP may either be riddled with several false positives (spikes that mismatch real weak spots) or be constructed out of true positive features with damped amplitude. This paper presents reweighed L1 minimization (RWL1), an enhancement to BP to both correct the dampening and discard false positives. This paper introduces RWL1 with examples from simulated data to show its advantage over vanilla BP denoising, plus a demonstration featuring real TSD measurements from a networkwide survey to demonstrate RWL1’s potential as an exploratory analysis tool to detect structurally weak locations within the pavement network worthy of further investigation at the project level.

A new load bearing capacity assessment method of the road pavement based on surface strain and the spectrum of the acceleration

Based on the coupling res model of vehicular and road, the influences of surface layer modulus, surface layer thickness and equivalent modulus of elasticity on the spectrum of the acceleration, surface deflection under wheels, and surface strain at the distance of 0.4 m to 0.8 m away from wheels are analyzed. Results show that the fundamental frequency of the road pavement increases with the growth of surface layer modulus and equivalent modulus of elasticity, and decreases with the increase of surface layer thickness. Both surface deflections and surface strains decrease with the increase of equivalent modulus of elasticity as well as surface layer modulus and thickness. Moreover, when the equivalent modulus of elasticity is more than 2500 MPa and surface layer modulus is more than 4000 MPa, surface deflections and surface strains have a little variation with the enhance of the surface layer modulus and equivalent modulus of elasticity. The solution method of the spectrum of the acceleration and equivalent modulus of elasticity, surface deflection under wheels, surface strain at the distance of 0.4 m to 0.8 m away from wheels, and surface deflection based on surface strain are established. The load bearing capacity assessment method of the road pavement based on surface strain and the spectrum of the acceleration is provided. Finally, the feasibility and accuracy of this method is verified by comparing measured values in field testing. The method in this paper provides a theoretical support for the design, construction and maintenance of road engineering.

Integrated Flight Control System Characterization Approach for Civil High-Speed Vehicles in Conceptual Design

Recent studies have revealed that control surface deflection can cause a reduction in the aerodynamic efficiency of a hypersonic aircraft of up to 30%. In fact, the characterization of the Flight Control System is essential for the estimation of the consistent aerodynamic characteristics of the vehicle in different phases, considering the contribution of control surfaces to stability and trim. In terms of the sizing process, traditional methodologies have been demonstrated to be no longer applicable to estimations of the actuation power required for the control surfaces of a high-speed aircraft, due to their peculiar working conditions and to the characteristics of the flow to which they are exposed. In turn, numerical simulation approaches based on computational fluid dynamics or panel methods may require considerable time resources, which do not fit with the needs of the quick and reliable estimates that are typical of the early design phases. Therefore, this paper is aimed at describing a methodology to show how to anticipate the Flight Control System design for high-speed vehicles at the conceptual design stage, properly considering the interactions at vehicle level and predicting the behavior of the system throughout an entire mission. It is also a core part of the work to provide designers with an example of how neglecting the effect of trim drag can be detrimental to a reliable estimation of overall aircraft performance. The analysis, mainly focused on the longitudinal plane of the vehicle, is presented step-by-step on a specific case study, namely the STRATOFLY MR3 vehicle, a Mach 8 waverider concept for civil antipodal flights. The application of the methodology, conceived as an initial step towards an iterative Flight Control System design process, also shows that the most power-demanding phases are take-off, low supersonic acceleration, and approach, where peaks of over 130 kW are reached, while an average of 20 kW is sufficient to support deflections in a hypersonic cruise.

Non-contact Ultrasonic Sonar-based Ranging Technique for In-motion 3D Railroad Tie Deflection Measurements

This paper presents an ultrasonic technique for non-contact surface deflection mapping of railroad ties using concepts of sonar-based ranging. The technique utilizes an array of capacitive ultrasonic transducers arranged along the length of the railroad tie at a lift-off distance of 3 in. from the rail surface to ensure contactless measurements. The transducer array is used in pulse-echo mode and distances from the transducers to the tie surface are measured by tracking the time-of-flight of the waves reflected from the tie surface. A reference-based cross-correlation operation is introduced to compute the time-of-flight, wherein one of the transducers is used as a reference for the distance measurements. The reference-based cross-correlation ensures accurate peak-detection for time-of-flight based differential distance measurements. An acoustic signal strength-based technique is utilized to differentiate between signals reflected from ties and those reflected from ballast. Laboratory scale tests were first performed as a proof-of-concept on a slender wooden beam to measure deflections in loaded and unloaded conditions. Dynamic tests were also performed on this beam to determine the ability to track time-varying positions. Field tests on a replica test track with wood ties were performed at the Rail Defect Testing Facility at University of California San Diego by mounting the prototype on a test-cart moved at walking speed. A dynamic assessment of the prototype was also performed to determine natural frequencies of the mounting beam that may be relevant for future uses at higher speeds. The results indicate the potential of this non-contact system to measure full-field tie deflections in 3D in-motion. This ability may potentially be used to detect conditions of poor tie support that may cause derailments.

Suitability of rubberised oil palm shell layers to stabilise concrete block pavement systems

ABSTRACT This study focuses on evaluating the response of concrete block pavement (CBP) reinforced with rubberised oil palm shell (ROPS) layers when subjected to vehicular loads using laboratory experiments and finite element (FE) simulations. The key parameters considered in this study are the sand bed thickness, oil palm content in ROPS layers, embedment depth of ROPS layers, and vehicle velocity. The dynamic loads due to the vehicular movement were generated using a real-time road unevenness signal. Outcomes from the lab-scale 1g experiments and FE simulations were expressed as displacement and acceleration responses in the frequency domain. CBP sections with sand bed thicknesses of 10mm and 70mm were found to yield high surface deflection and acceleration values, both with and without ROPS reinforcements. CBPs reinforced with the ROPS layer having 20% OPS content demonstrate the best performance compared to ROPS layers made with 5% and 10% OPS contents. Further simulations show that the ROPS layers at an optimum embedment depth of 180mm from the surface in the CBP profile can significantly reduce the unacceptable levels of vibration. To this end, this preliminary research attempts the possible reengineering of oil palm shells and ascertains the suitability of ROPS reinforcements in stabilising CBP−soil systems.

Reconfiguration Incremental Control Allocation for Tailless Aerial Vehicle with Control Surface Faults

To address the faults of the tailless aerial vehicle control surface with nonlinear control effectiveness, a reconfiguration incremental control allocation method is proposed. Under the framework of incremental control allocation, four types of typical control surface faults, such as floating, jamming, damaged, and median offset, are modeled. The isolation of faulty control surfaces and the reconfiguration of the flight control system is realized by adjusting the control surface deflection increment limit and changing the local control effectiveness matrix. The results show that the method can effectively take advantage of the redundant configuration of the control surface, prevent the system from losing control caused by the fault of the control surface, and enhance the safety and reliability of the system.

Flight Dynamics Modeling and Aerodynamic Parameter Identification of Four-Degree-of-Freedom Virtual Flight Test

Compared with the forced oscillation test in a conventional wind tunnel test, the wind tunnel virtual flight test can achieve partially constrained dynamic motion of the model in the wind tunnel by manipulating the control surface deflection. In this paper, a new four-degree-of-freedom (4-DOF) wind tunnel virtual flight test device is established. Compared with the 3-DOF wind tunnel virtual flight test with rotation around the center of mass, the model adds vertical motion, enabling it to simulate free flight more realistically. In this paper, the nonlinear flight dynamics model of 4-DOF wind tunnel virtual flight test is established, the differences in dynamics characteristics between it and free flight are analyzed, and the identification model of aerodynamic derivatives based on 4-DOF wind tunnel virtual flight test is derived. To ensure the safety of the test, the longitudinal altitude control law as well as the sideslip and roll angle control laws in the lateral direction are designed. Finally, a set of aerodynamic parameter identification methods based on a 4-DOF wind tunnel virtual flight test is formed. The output error method is used to identify the aerodynamic derivatives of the test model, and the accuracy of the identification results is higher than that of the 3-DOF wind tunnel virtual flight test.

EHD stability of a cylindrical boundary separating double Reiner–Rivlin fluids

The major aim of this work is to achieve a mathematical technique to scrutinize the nonlinear instability of a vertical cylindrical boundary separation of two streaming Reiner–Rivlin liquids. The system is portrayed by an unchanged longitudinal electric strength. Furthermore, the action of mass and heat transfer (MHT) and permeable media are also considered. The problem is not only of methodological interest but also of scientific and practical interest. To shorten the mathematical analysis, Hsieh’s modulation together with the viscous potential theory (VPT) is employed. The nonlinear diagram is contingent on tackling the governing linear mechanism along with the nonlinear applicable border restrictions. A non-dimensional process produces several non-dimensional physical numbers. A linear dispersion equation is attained and the stability standards are theoretically governed and numerically established. The nonlinear stability procedure reveals a Ginzburg–Landau formula. Consequently, nonlinear stability stipulations are accomplished. Furthermore, by way of the Homotopy perturbation approach, along with the expanded frequency concept, an accurate perturbed technique of surface deflection is attained theoretically and numerically. To validate the theoretical outcomes, the analytical expression is confirmed through the Rung–Kutta of the fourth order. The stable and unstable zones are signified graphically displaying the influences of several non-dimensional numbers.

Structural Behavior Prediction Model for Asphalt Pavements: A Deep Neural Network Approach

Abstract Structural behavior of pavements is assessed using various destructive and nondestructive tests, albeit they are found to be cost-intensive. There is a need to develop cost-effective structural condition evaluation methods that are scientifically sound so appropriate maintenance interventions can be performed at the right time. The objective of this research study was to develop a Deep Neural Network (DNN)–based approach to predict pavement structural condition using functional, traffic, and climatic characteristics. A DNN was developed to calculate the deflection bowl parameters along with peak surface deflections from roughness, traffic, pavement age, pavement temperature, and climatic conditions. Over 26,000 data points covering various geographic locations were used to establish a global model (R2 = 82 % for the test data) to evaluate the structural integrity of asphalt pavement layers. It is envisioned that this study would assist roadway agencies in assessing the overall condition of asphalt pavements synergizing functional and structural characteristics.

A new tire-sensor-pavement coupling chain for investigating asphalt mixture responses under rolling tire loads

Understanding the mechanisms for road surface degradation requires an examination of asphalt layer responses under realistic rolling tire loads. In this study, we proposed a novel tire-sensor-pavement coupling chain for integrating the realistic distribution of tire contact stress into the mechanical modelling of the asphalt layer. The tire contact stress distributions under different tire loading conditions including tire loads and tire inflation pressures are obtained by using a sensor measuring system. The temperature- and frequency-dependent material behaviour of asphalt mixes is described through the VENoL (NOnLinear Viscoelastic) model. The model reliability is validated by numerical/experimental confrontation via a series of complex modulus tests. A new algorithm is developed to achieve the coupling simulation of the tire–pavement interaction system. Finally, the dynamic responses of the asphalt mixture including external force, displacement fields and surface deflection were investigated depending on rolling tire loads. The proposed method provides a fundamental requirement for understanding the structural behaviour of asphalt pavement loaded by rolling tires, which can be used to get insights into asphalt pavement surface design.

Prediction of remaining service life for flexible pavement in the Southern Central States using FWD parameters

Various Departments of Transportation (DOTs) in the South-Central States and abroad have extensively used Non-Destructive Testing (NDT) surface deflection bowl data. The primary purpose of using deflection-based NDTs in network-level assessment is to identify a section of pavement in need of further investigation at the project level. The falling weight deflectometer (FWD) test is a common NDT-based test that is used by transportation agencies to assess the performance of flexible pavement.This research concentrates on simulating the deflection produced by FWD devices using 3-D Move software. Simulations based on software will decrease the need for lengthy FWD testing in the field. In the study, ninety-seven (97) pavement sections from Arkansas, Louisiana, New Mexico, Oklahoma, and Texas are used for simulation, analysis, and verification of FWD testing. The deflection values produced from software simulations were found to be strongly correlated with field test findings. In addition, the simulated deflection values were used to develop and validate various deflection bowl parameters. In this study, the normalized comprehensive deflection ratio and the normalized comprehensive area ratio are two key characteristics that were validated and produced. Eventually, load-induced impacts using these parameters are effectively analyzed in order to anticipate the remaining service life of flexible pavement structures. The prediction of the remaining service life will be an efficient tool for different DOTs and transportation agencies to initiate the rehabilitation work in time and economically.

Prediction of remaining service life for flexible pavement in the Southern Central States using FWD parameters

Various Departments of Transportation (DOTs) in the South-Central States and abroad have extensively used Non-Destructive Testing (NDT) surface deflection bowl data. The primary purpose of using deflection-based NDTs in network-level assessment is to identify a section of pavement in need of further investigation at the project level. The falling weight deflectometer (FWD) test is a common NDT-based test that is used by transportation agencies to assess the performance of flexible pavement.This research concentrates on simulating the deflection produced by FWD devices using 3-D Move software. Simulations based on software will decrease the need for lengthy FWD testing in the field. In the study, ninety-seven (97) pavement sections from Arkansas, Louisiana, New Mexico, Oklahoma, and Texas are used for simulation, analysis, and verification of FWD testing. The deflection values produced from software simulations were found to be strongly correlated with field test findings. In addition, the simulated deflection values were used to develop and validate various deflection bowl parameters. In this study, the normalized comprehensive deflection ratio and the normalized comprehensive area ratio are two key characteristics that were validated and produced. Eventually, load-induced impacts using these parameters are effectively analyzed in order to anticipate the remaining service life of flexible pavement structures. The prediction of the remaining service life will be an efficient tool for different DOTs and transportation agencies to initiate the rehabilitation work in time and economically.

A Review Study on the Performance of Flexible Pavements

Pavements are significant resources of expressway infrastructure. The nation has seen colossal expansion in the vehicle population and expanded hub stacking design during the last decade, leaving its street network overemphasized and prompting untimely disappointment. The kind of weakening present in the asphalt ought to be considered for deciding if it has a useful or underlying inadequacy, so that suitable overlay type and configuration can be created. The structural properties of asphalt are redirection and it is completed by Benkelman Beam & deflectometer test. The evaluation of street conditions is needed to distinguish the explanations behind disintegration before any restoration work is completed. The fundamental boundaries including in the appraisal of street conditions are avoidance and unpleasantness estimation which decided utilizing different test, for example, FWD, Benkelman shaft test, profilometer, and slide obstruction test. This appraisal additionally helps in focusing on the upkeep works as indicated by the necessity. A few procedures are utilized to evaluate the road conditions and contrast and standard standards. In this concentrate on a stretch of road is break down for similar where techniques utilized are visual strategy, Benkelman beam test and slide opposition test. The structural and useful assessment are dissected and created by different specialists. The paper presents an itemized audit of different asphalt exhibitions on primary and utilitarian assessment of adaptable asphalt to inspect the job of components identified with asphalt materials, surface deflection, ecological conditions, sort of traffic and volume of traffic, and to distinguish the constraints and holes in the current information on such examinations.

Assessment Performance of Flexible Pavements for Surface Deflection Measure by Benkelman Beam Method

AbstractThe condition of roads assumes significant part since it straightforwardly influence traveler just as cargo traffic. The decayed street having undesired diversion or deficient harshness makes inconvenience rider and may even bring about road mishaps. This insufficiency in road attributes can be classifications as both useful and underlying. The evaluation of street conditions is needed to distinguish the explanations behind disintegration before any restoration work is completed. The fundamental boundaries including in the appraisal of street conditions are avoidance and unpleasantness estimation which decided utilizing different test, for example, FWD, Benkelman shaft test, profilometer, and slide obstruction test. This appraisal additionally helps in focusing on the upkeep works as indicated by the necessity. A few procedures are utilized to evaluate the road conditions and contrast and standard standards. In this concentrate on a stretch of road is break down for similar where techniques utilized are visual strategy, Benkelman beam test, and slide opposition test. Utilizing last two methods, surface diversion and skid resistance is surveyed, and restorative measure are recommended for the road stretch.

Innovative modeling and simulation of membrane-based dehumidification and energy recovery equipment

Membrane-based dehumidification is a promising solution for building applications because of its low cost and limited energy consumption. Developing an efficient and cost-effective open-source code simulation tool is important for optimizing and evaluating such devices in HVAC applications. This paper describes a physics-based model, which accounts for the fundamental heat and mass transfer between a humid-air vapor stream on the feed side and a flowing stream on the permeate side of a membrane. The developed model comprises two mass transfer submodels—a microstructure model and a performance map model—and adopts a segment-by-segment method for discretizing heat and mass transfer governing equations for flow streams on the feed and permeate sides of a membrane. The model can simulate dehumidifiers and energy recovery ventilators with parallel-flow, cross-flow, and counter-flow configurations, and the predictions compare reasonably well with the measurements. The model was used to evaluate the effect of membrane microstructure parameters and membrane surface deflection factors, as well as to investigate the performance of combined dehumidification and energy recovery exchangers. The model and C++ open-source codes are expected to become a fundamental tool in analyzing future membrane-based dehumidification systems.

Robust Design of Deep Drawing Process through In-Line Feedback Control of the Draw-In

In the deep drawing process, the scatter of the friction coefficient between blank and tool interfaces as well as of the material properties between blank positions in the coil or between different coils significantly influences the part quality. These uncontrollable fluctuations increase the risk of waste. To avoid this problem, currently, the new era of Industry 4.0 aims at developing control algorithms able to in-line adjust process parameters and always meet the part quality requirements. Starting from this context, in this study a method for process control during the punch stroke is proposed. It assumes the blank draw-in in specific points as the control variable, while the blank holder force is adopted as an in-line adjustable process parameter. The approach was implemented for the deep drawing of a T-shaped component, using a blank in DC05 steel with a thickness of 0.75 mm. The results show that the measurement of blank draw-in is a representative index of the component quality, which in this study is evaluated in terms of formability (thinning) and cosmetic (surface deflections) defects. Once the optimal condition and the corresponding blank draw-in were identified, the feedback control algorithm was able to increase or reduce the blank holder force according to whether the recorded draw-in was higher or lower than the optimal one.

Characterisation and Quantification of Upper Body Surface Motions for Tidal Volume Determination in Lung-Healthy Individuals.

Measurement of accurate tidal volumes based on respiration-induced surface movements of the upper body would be valuable in clinical and sports monitoring applications, but most current methods lack the precision, ease of use, or cost effectiveness required for wide-scale uptake. In this paper, the theoretical ability of different sensors, such as inertial measurement units, strain gauges, or circumference measurement devices to determine tidal volumes were investigated, scrutinised and evaluated. Sixteen subjects performed different breathing patterns of different tidal volumes, while using a motion capture system to record surface motions and a spirometer as a reference to obtain tidal volumes. Subsequently, the motion-capture data were used to determine upper-body circumferences, tilt angles, distance changes, movements and accelerations-such data could potentially be measured using optical encoders, inertial measurement units, or strain gauges. From these parameters, the measurement range and correlation with the volume signal of the spirometer were determined. The highest correlations were found between the spirometer volume and upper body circumferences; surface deflection was also well correlated, while accelerations carried minor respiratory information. The ranges of thorax motion parameters measurable with common sensors and the values and correlations to respiratory volume are presented. This article thus provides a novel tool for sensor selection for a smart shirt analysis of respiration.

Nonlinear EHD instability of two viscoelastic fluids under the influence of mass and heat transfer

This study attempts to provide an approach to studying the nonlinear stability of a vertical cylindrical interface between two Oldroyd-B prototypes. An unchanged axial electric field influences the system, and porous medium, and the effects of heat and mass transfer (MHT) are considered. Hsieh's modulation and the viscous potential flow (VPT) are used to abbreviate the mathematical analysis. The viscoelastic Oldroyd-B model significant role in geothermal, engineering and industrial enhancement motivated us to carry out this in-depth investigation. The methodology of the nonlinear technique depends mainly on solving the linear equations of motion and applying the appropriate nonlinear boundary conditions. Numerous non-dimensional physical numbers are exposed using a non-dimensional technique. The stability conditions are theoretically achieved and numerically verified. As a limiting case, the linear dispersion equation is accomplished, and a set of stability diagrams is reachable. Together with the nonlinear stability method, a Ginzburg–Landau equation is derived. Subsequently, both theoretical and numerical methods are used to achieve the nonlinear stability criteria. Furthermore, a precise perturbed approach for surface deflection is achieved theoretically and numerically using the Homotopy perturbation method and the extended frequency conception. Along with the linear approach, it is found that the structure becomes unstable by the Laplace, Reynolds, Weber, and elasticity quantities as well as the linear MHT parameter. Furthermore, the stability zones are enhanced in the nonlinear instability approach.

Soil-structure pile foundation interaction model due to lateral loading

Experimental research on piles, by models and physical tests on a laboratory scale, using materials and sizes that are different from the prototypes. The model is designed, treated, and interpreted the results of observing the response based on similarity using Model theory, but the soil sample cannot be modeled with model theory, giving rise to doubts similarity of the research. This study was conducted to examine the effect of pile-soil interaction on several views of the elastic modulus of the soil due to lateral loads. Laboratory model pile foundations are laterally loaded, on soil samples in a test box. The deflection of the pile foundation is analyzed based on the use of linear, layered, and non-linear modulus of elasticity. A non-linear simulation of the Winkler model with a spring along the depth of the pile was carried out to calibrate the horizontal deflection of the laboratory experimental model. The results showed that the Winkler model's modulus of elasticity was approximately 40% of the pile length, and the non-linear difference between the Winkler and laboratory models was 10.77%, comparisons can be conclusive about the need for similar research on lateral loading of laboratory model piles. The analysis also noted that the surface deflection was determined by winkler’s model elastic modulus analysis with an excess of about 12% to 14% in the first 10% of the pile length.

Supersonic flow unsteadiness induced by control surface deflections

Control surface deployment in a supersonic flow has many applications, including flow control, mixing, and body-force regulation. The extent of control surface deflections introduces varying flow unsteadiness. The resulting fluid dynamics influence the downstream flow characteristics and fluid–structure interactions significantly. In order to understand the gas dynamics, an axisymmetric cylindrical body with a sharp-tip cone at zero angles of attack (α=0°) is examined in a free stream Mach number of M∞=2.0 and Reynolds number of ReD=2.16×106 (D = 50 mm). Four static control surface deflection angles (θ=π/36,π/6,π/3, and π/2 rad) are considered around the base body. The cases are computationally investigated through a commercial flow solver adopting a two-dimensional detached eddy simulation strategy. Recirculation bubble length, drag coefficient's variation, wall-static pressure statistics, acoustic loading on the model and the surroundings, x − t trajectory and x − f spectral analysis, pressure fluctuation's correlation coefficient on the model, and modal analysis are obtained to understand the flow unsteadiness. At θ=[π/36], the wall-static pressure fluctuations behind the control surface are minimal and periodic, with a mere acoustic load of about 50 dB. At θ=[π/2], a violent periodic fluctuation erupted everywhere around the control surface, leading to a higher acoustic load of about 150 dB (three times higher than the previous). For θ=[π/6] and [π/3], high-frequency fluctuations with small- and large-scale structures continuously shed along the reattaching shear layer, thereby causing a broadened spectra in the control surface wake.