Longitudinal Velocity Measurements Research Articles

Active Control for an Electric Vehicle with an Observer for Torque Energy-Saving

Vehicle dynamics play an important role in determining a vehicle’s stability. It is necessary to identify and obtain models related to vehicle dynamics to evaluate the performance of electric vehicles, as well as how to control them. This paper presents fundamentals of vehicle dynamics, proposing a three-degree-of-freedom nonlinear observer and controller to control lateral velocity and tire torque in comparison to a PID control, while also utilizing a Lyapunov function to determine the stability of the controlled state feedback system concerning the observer, which estimates state errors. This work demonstrates the mathematical development of estimations that will be fed into the algorithms of two active nonlinear controls (state feedback and PID), utilizing the results from Matlab-Simulink simulations of tire torque, lateral and angular velocities based on longitudinal velocity measurements, and employing dynamic gains, such as response to a steering maneuver by the driver following the international standards ISO 7401/2011 and ISO 3888-2. It is concluded that the observer is robust and exhibits energy-saving efficiency in tire torque, even under conditions of variable tire-ground friction.

Profiles of high-order moments of longitudinal velocity explained by the random sweeping decorrelation hypothesis

The generalized log law for the high-order moments of longitudinal velocity with distance from a boundary in the inertial region is derived from the following assumptions: that the random sweeping decorrelation hypothesis applies; that the velocity statistics are near-Gaussian; and that the longitudinal velocity spectrum scales as ${k}^{\ensuremath{-}1}$ in the intermediate region. Measurements of longitudinal velocity collected within the first meter from the surface in the western deserts of Utah show good agreement with the proposed theory even under mild thermal stratification.

Dynamics of submerged jet flow in a pipe in a longitudinal magnetic field

A submerged jet flow of an electrically conductive liquid in a longitudinal uniform magnetic field is considered. The flow is formed by a sudden expansion of the flow from a hole into a pipe (with a diameter ratio of 1 to 5) filled with the same liquid at a constant flow rate. The study was carried out using the method of direct numerical simulation. The simulation results are compared with the averaged longitudinal velocity measurements obtained in the experiments on mercury. The Reynolds numbers correspond to the turbulent flow in the jet at the inlet and the laminar flow at the outlet of the pipe. In a moderate magnetic field, with an increase in the Hartmann number in the flow, turbulent transport is suppressed. The flow is largely laminarized up to the jet front, where, due to instability, it passes to turbulence. The effective length of the jet increases with increasing the Hartmann number, since the resulting electromagnetic force prevents the jet expansion. In strong magnetic fields, there is a tendency for the flow to be unstable due to the interaction of the formed secondary flows with the magnetic field. The radial components of the induced electric current arising in this case in the flow cause transverse stretching and compression of the jet profile by the electromagnetic force. Time-variable deformations of the jet profile and their spatial inhomogeneity in a magnetic field lead to the appearance of an ordered flow swirl. The swirl rate depends on the Hartmann number and, in the studied range of Reynolds numbers, does not exceed 12% of the average outlet flow rate. The development of instability is accompanied by time alternations of intervals in which the flow has significantly different amplitudes of velocity fluctuations.

Incorporating direct metal laser sintered complex shaped Ti-6Al-4V components in ultrasonic surgical devices.

Additive manufacturing (AM) offers opportunities to design more complex shapes of the Ti-6Al-4V parts commonly used in high-power ultrasonic surgical devices. Moreover, AM metal printing will be essential to the realization of miniature ultrasonic devices incorporating internal structures for minimally invasive surgical procedures. However, it is necessary first to verify the ultrasonic vibrational behavior of devices with three-dimensional (3D) printed metal parts. Therefore, two different prototype devices are fabricated, with CNC machined mill annealed and 3D printed Ti-6Al-4V parts. Both devices, an ultrasonic bone needle and a miniature ultrasonic scalpel, incorporate complex geometries but can be manufactured using subtractive processes so that the comparative effects of 3D printing on the vibrational performance of the devices can be elucidated. The metal microstructure is investigated through measurements of longitudinal and shear acoustic velocities and scanning electron microscopy. Comparisons of electrical impedance, frequency and modal responses, and the vibrational response at increasing levels of excitation enable evaluation of the efficacy of incorporating 3D printed Ti-6Al-4V parts. Results show that whereas the bone needle exhibited comparable vibrational responses for the measurement techniques used, the 3D printed bone cutting device exhibited a more dense modal response and developed cracks at high excitation levels.

The elastic constants measurements in a TI-6AL-4V eli alloy by ultrasound

In this paper, we report the calculation of the elastic constants such Poisson's ratio, elastic modulus and shear modulus deduced from the ultrasonic propagating equations with two types of ultrasonic vibrations named longitudinal and transverse waves. The ultrasonic propagating velocity is measured at the microstructural evolution in a Ti-6Al-4V medical alloy with two varying microstructures, bimodal and acicular respectively. The two different initial microstructures were treated thermally by aging at 515 °C, 545 °C, and 575 °C at different times from 1 min to 576 h to induce a precipitation process. Ultrasonic measurements of shear and longitudinal wave velocities, scanning electron microscopy (SEM) image processing and micro-hardness were performed, establishing a direct correlation with the measurements of the ultrasonic velocity and the elastic properties developed during the thermal treatment of the artificial aging. The results of the ultrasonic velocity show a very clear trend as the aging time progresses, which is affected by precipitation of Ti3Al particles inside the α phase. In this way, we can know, in a fast and efficient way, the elastic properties developed during the heat treatment of aging at long times, since the presence of these precipitates hardens the material microstructure affecting the final mechanical properties.

NDT evaluation of age hardening kinetics of RT and Cryo – ECAPed Aluminum 6063 alloy from attenuation coefficient and longitudinal velocity measurements obtained by ultrasonic testing

Equal Channel Angular Pressing (ECAP) has been attracting much attention from the material community, because of its ability to produce ultrafine-grained microstructures. The uniqueness of ECAP is that, extensively high strains can obtained in the material without significant change in geometric shape or cross-sectional area. Al6063 alloys were solution treated at 520 °C for 2 h and quenched in water. One set of water-quenched samples directly processed by ECAP and another set of samples treated with liquid nitrogen for about 20 min and then subjected for ECAP. The processed alloys were aged at 180 °C and the age hardening behaviour correlated with the attenuation coefficient and longitudinal velocity measurements obtained by ultrasonic testing. SEM studies also performed and a close agreement between age hardening behaviour, attenuation coefficient, longitudinal velocity and microstructure has observed.

Mechanical and Non-Destructive Testing of Plasterboards Subjected to a Hydration Process.

The aim of this study was to investigate the effect of plasterboards’ humidity absorption on their performance. Specimens’ hydration procedure consisted of consecutive immersing in water and subsequent drying at room temperature. Such a procedure was performed to increase the content of moisture within the material volume. The microstructural observations of five different plasterboard types were performed through optical and scanning electron microscopy. The deterioration of their properties was evaluated by using a three-point bending test and a subsequent ultrasonic (ultrasound testing (UT)) longitudinal wave velocity measurement. Depending on the material porosity, a loss of UT wave velocity from 6% to 35% and a considerable decrease in material strength from 70% to 80% were observed. Four types of approximated formulae were proposed to describe the dependence of UT wave velocity on board moisture content. It was found that the proposed UT method could be successfully used for the on-site monitoring of plasterboards’ hydration processes.

Determination of the Elastic Properties at Aging of Medical Ti-6Al-4V ELI Alloy by Ultrasonic Velocity Measurements

In this paper, we report the experimental data of the elastic properties of the Young’s modulus and shear modulus based on the variation in the ultrasonic velocity parameter during the microstructural evolution in a Ti-6Al-4V alloy with two—bimodal and Widmanstatten—varying microstructures. The two different initial microstructures were treated thermally by aging at 515, 545, and 575°C at different times from 1 min to 576 h to induce a precipitation process. Ultrasonic measurements of shear and longitudinal wave velocities, scanning electron microscopy image processing, optical microscopy, and microhardness measurements were performed, establishing a direct correlation with the measurements of the ultrasonic velocity and the elastic properties developed during the thermal treatment by artificial aging. The results of the ultrasonic velocity show a very clear trend as the aging time progresses, which is affected by precipitation of Ti3Al particles inside the α phase. In this way, we can find, in a fast and efficient way, the elastic properties developed during the heat treatment by long-term aging, since the presence of these precipitates hardens the material microstructure, thus affecting the final mechanical properties.

Young’s Modulus Determination of Polyester and Epoxy by Means of Ultrasonic Pulse Echo Testing

The Young’s modulus or elasticity modulus is material ability to resist elastic deformation when loaded. Thermosetting polymers have a wide range of modulus elasticity values. To determine the elasticity modulus value, materials need to be destructive tested, such as tensile test or bending test. But in industrial field, they avoided destructive test. Theoretically, the modulus of elasticity can also be determined by ultrasonic testing pulse echo method. This method has already applied successfully for metals material. The goal of this research was to evaluate probe used in longitudinal velocity measurement of polyester and epoxy and to determine Young’s Modulus of polyester and epoxy by means ultrasonic pulse echo testing. This method was performed using three longitudinal probes that have different diameters, frequencies, and additional delay line. The specimens were varied with different thicknesses. The ultrasonic pulse echo method uses probe 3 with a diameter of 12.7mm, a frequency of 1.5MHz, and additional delay line is most suitable to measure the longitudinal velocity of polyester and epoxy with thickness of 2.82-36.72 mm. Probe 3 has a smaller diameter and additional delay lines thus eliminating the effect of dead zones. The elastic modulus error of thermoset polymer material through ultrasonic testing of pulse echo method compared to the mechanical modulus of elasticity is still very large, i.e. 102% for epoxy, and 159% for polyester. A large error is caused by attenuation and the use of the elasticity modulus equation from ultrasonic testing that still requires modification.

Thermophysical properties of reservoir rocks

Ultrasonic measurements of longitudinal and transverse velocities and of grain density are used to determine a number of thermophysical properties of limestone, dolomite, and siliciclastic rocks of a hydrocarbon reservoir with use of thermoelastic and thermodynamic equations. The equations for the Grüneisen parameter and melting temperature are written in density-independent form suitable for the analysis of the available data. The present study shows that adiabatic compressibility (κS) of the rocks increases (bulk modulus decreases) exponentially. Thermal conductivity (Kl) and thermal diffusivity(D) are determined with an empirical relation. The values of κS, Kl, and D at zero porosity are comparable with the reported values. The Grüneisen parameter and melting temperature decrease nonlinearly but the Debye temperature decreases linearly with increasing porosity. Dolomite stands out as the most massive compared with limestone and siliciclastic rocks.

External intermittency compensation of dissipation scale distributions in a turbulent boundary layer

We investigate the effect of external intermittency on dissipation scales in turbulent boundary layer flow at $R\phantom{\rule{0}{0ex}}{e}_{\ensuremath{\tau}}\ensuremath{\approx}1000$ using a single hot wire probe for one point longitudinal velocity measurements. We find improved scaling universality by accounting for external intermittency throughout the flow.

Modeling of wood properties from parameters obtained in nursery seedlings

Early selection of trees allows acceleration of genetic improvement, as well as processes related to forest management, to improve the quality of the wood produced; however, to reach this objective, it is necessary to know which parameters can be used as predictors of a tree’s aged condition. The objective of this research was to study parameters that are measurable in nursery seedlings and that could be used in prediction models of basic density (BDt), modulus of elasticity (EMt), and strength (fmt) of wood from trees. The tests were performed in 240 seedlings (3 and 6 months old) and in 52 trees (72 months old) from seven genetic units of two species: three Eucalyptus clones and four Pinus pinaster progenies. In the seedlings, measurements of longitudinal velocity of ultrasonic waves (VLs), basic density (BDs), height (Hs), diameter (Ds), strength (fts), and modulus of elasticity (Ets) in tension parallel to the grain were obtained. The EMt and fmt can be predicted by parameters obtained in seedlings of the same genetic unit. Thus, the use of these parameters, in association with others already used in selection programs, may increase the positive results of the early selection, with economic gains and time reductions in forest management.

In-pipe coconut water rheological characterization with ultrasonic waves

We propose in this paper to use a simple and robust experimental protocol based on longitudinal ultrasonic velocity measurement in order to evaluate the viscosity of coconut water in a cylindrical stainless-steel pipe. Seven samples with Soluble Solids Content (SSC) ranging from 6.7 to 44.2°Brix were studied using conventional Couette viscometry and high-frequency ultrasonic methods. Calibration laws linking the ultrasonic velocity measured at 5 MHz to the shear viscosity and to the SSC are proposed. These laws are in very good agreement with previous measurements carried out several years ago using a plane 25 MHz transducer directly introduced into the coconut water with SSC of up to 60°Brix.

Tunning of metal-insulator phase transition temperature in La0.3Ca0.7MnO3 perovskite material

In recent years, there is an increasing demand for more sensitive and high magnetoresistive materials in high-speed electronic and magnetic devices. La1−xCaxMnO3 perovskites are chosen to be beneficial for the potential applications in solid oxide fuel cells, magnetic sensors/reading heads and frequency switching devices. La0.3Ca0.7MnO3 perovskites were prepared and sintered at four different temperatures such as 1173, 1273, 1373 and 1473 K. X-ray powder diffraction pattern confirms the existence of orthorhombic structure with Pnma space group in the perovskites. Scanning electron microscopy images of the perovskites were used to determine the size of the particles. In situ measurement of ultrasonic longitudinal velocity was carried out over a wide range of temperature. The ultrasonic measurements have shown an interesting anomaly at the metal-insulator phase transition. The metal insulator transition temperature is found to increase from 625 to 640 K with the increase of sintering temperature.

A new adaptive tracking control scheme of wheeled mobile robot without longitudinal velocity measurement

SummaryThis paper proposes a new adaptive trajectory tracking control scheme of the wheeled mobile robot without longitudinal velocity measurement. First, based on a kinematic controller, we obtain a new tracking error equation, which is suitable to develop an adaptive controller. Then, we develop a new adaptive trajectory tracking controller, which does not need any accurate values of the wheeled mobile robot parameters, including the driving motor parameters. Moreover, as the longitudinal velocity measurement is still difficult, this controller is developed without longitudinal velocity measurement. In addition, this new adaptive controller introduces a method to improve the control performance. The stability of the closed‐loop system is presented using the direct Lyapunov method. Finally, numerous simulations verify the effectiveness of the new controller.

Hugoniot equation of state of rock materials under shock compression.

Two sets of shock compression tests (i.e. conventional and reverse impact) were conducted to determine the shock response of two rock materials using a plate impact facility. Embedded manganin stress gauges were used for the measurements of longitudinal stress and shock velocity. Photon Doppler velocimetry was used to capture the free surface velocity of the target. Experimental data were obtained on a fine-grained marble and a coarse-grained gabbro over a shock pressure range of approximately 1.5-12 GPa. Gabbro exhibited a linear Hugoniot equation of state (EOS) in the pressure-particle velocity (P-up) plane, while for marble a nonlinear response was observed. The EOS relations between shock velocity (US) and particle velocity (up) are linearly fitted as US = 2.62 + 3.319up and US = 5.4 85 + 1.038up for marble and gabbro, respectively.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

Rapid wave velocity measurement by Brillouin scattering using artificially induced phonon

Brillouin light scattering enables measurements of hypersonic longitudinal and shear velocities in the small area (diameter about 50 μm). One problem of the conventional Brillouin technique is the weak Brillouin scattering peak from thermal phonons and this results in the longer measurement time. To overcome this problem, we have proposed measurements of strong coherent phonons by fabricating a high frequency transducer on the sample surface. However, the fabrication of the transducer is not suitable for simple and nondestructive measurements. In this study, a small glass device with a ZnO piezoelectric thin film was used as a hypersonic transducer around 1 GHz. By attaching this transducer to the sample with coupling liquid, artificial coherent phonons were successfully induced in a sample. In the case of a quarts sample, strong Brillouin scattering peaks were observed using a tandem Fabry-Perot interferometer. The measured frequency shift of the peaks was equal to the excitation frequency of the ZnO pie...

Design of Ethernet based data acquisition system for yaw rate and longitudinal velocity measurement in automobiles

Design of an Ethernet network compatible data acquisition system for the measurement of yaw rate and longitudinal velocity in automobiles is presented. The data acquisition system includes a base node and a remote node. The remote node consists of a micro electro mechanical system (MEMS) accelerometer, an MEMS gyroscope, an advanced RISC machines (ARM) CORTEX M3 microcontroller and an Ethernet PHY device. The remote node measures the yaw rate and the longitudinal velocity of an automobile and sends the measured values to the base node using Ethernet communication. The base node consists of an ARM CORTEX M3 microcontroller and an Ethernet PHY device. The base node receives the measured values and saves in a microSD card for further analysis. The characteristics of the network and the measurement system are studied and reported.

Observer Design for LPV Systems With Uncertain Measurements on Scheduling Variables: Application to an Electric Ground Vehicle

In this paper, we aim to study the observer design problem for polytopic linear-parameter-varying (LPV) systems with uncertain measurements on scheduling variables. Due to the uncertain measurements, the uncertainties are considered in the weighting factors. It is assumed that the vertices of polytope are the same when the measurements on scheduling variables are uncertain and perfect. Then, an LPV system with the uncertain weighting factors can be transferred to an LPV system with uncertainties. To deal with the uncertainties and unknown disturbance in the observer design problem, we propose a gain-scheduling sliding mode observer. Defining the estimation error as the state vector minus the estimated state vector, the estimation error dynamics is established. The sliding mode observer design method is developed based on analysis results of the established estimation error system. The proposed observer design method is then applied to an electric ground vehicle (EGV) in which the measurement of longitudinal velocity is assumed to be uncertain. Experimental tests and comparisons are given to show the advantages of the proposed design method and the designed observer.

Phase Transitions in Smectic Bent-Core Main-Chain Polymer Networks Detected by Dielectric and Ultrasonic Techniques

The dielectric and ultrasonic properties of a bent-core main-chain liquid-crystalline polymer network have been investigated. Dielectric measurements on this material showed two maxima in the real and imaginary components of the dielectric permittivity at 365 K and 450 K along with a temperature hysteresis showing the first order nature of the two phase transitions. Longitudinal ultrasonic attenuation and ultrasonic velocity measurements at 10 MHz frequency revealed some anomalies at the phase transition temperatures respect to the dielectric results. Above room temperature, a large ultrasonic attenuation was observed which can be related to the glass transition of this sample. Moreover, the piezoelectric sensitivity of this bent-core main-chain liquid-crystalline polymer network has also been studied.