scholarly journals Blind Steppers Using Ultrasonic Sensors

2021 ◽  
pp. 331-337
Author(s):  
Ritvik Sethi ◽  
Shlok Kumar ◽  
Deepansh Gupta ◽  
Priyansh Kumar Mangal ◽  
Ansh Pujara
Keyword(s):  
Ultrasonic Wave ◽  
Ultrasonic Waves ◽  
Ultrasonic Sensors ◽  
Sensor Head ◽  
Walking Stick

The ultrasonic sensors measure distance by using ultrasonic waves. The sensor head emits an ultrasonic wave and receives the wave reflected back from the target. Ultrasonic Sensors measure the distance to the target by measuring the time between the emission and reception. By using the above application the shoes designed provide a vibration when an obstacle comes near to the shoe. The shoes helps the blind to walk freely unlike traditionally when they need to always carry a walking stick which was not much reliable. The shoes are designed and programmed to alarm the stepper when a massive obstacle reaches within its range of 0-0.5 meters.

scholarly journals Linear and Nonlinear Normal Interface Stiffness in Dry Rough Surface Contact Measured Using Longitudinal Ultrasonic Waves

2021 ◽  
Vol 11 (12) ◽  
pp. 5720
Author(s):  
Saeid Taghizadeh ◽  
Robert Sean Dwyer-Joyce
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Ultrasonic Wave ◽  
Bulk Material ◽  
Nonlinear Differential Equations ◽  
Small Deformation ◽  
Ultrasonic Waves ◽  
Solid Contact ◽  
Interfacial Stiffness ◽  
Linear And Nonlinear

When two rough surfaces are loaded together contact occurs at asperity peaks. An interface of solid contact regions and air gaps is formed that is less stiff than the bulk material. The stiffness of a structure thus depends on the interface conditions; this is particularly critical when high stiffness is required, for example in precision systems such as machine tool spindles. The rough surface interface can be modelled as a distributed spring. For small deformation, the spring can be assumed to be linear; whilst for large deformations the spring gets stiffer as the amount of solid contact increases. One method to measure the spring stiffness, both the linear and nonlinear aspect, is by the reflection of ultrasound. An ultrasonic wave causes a perturbation of the contact and the reflection depends on the stiffness of the interface. In most conventional applications, the ultrasonic wave is low power, deformation is small and entirely elastic, and the linear stiffness is measured. However, if a high-powered ultrasonic wave is used, this changes the geometry of the contact and induces nonlinear response. In previous studies through transmission methods were used to measure the nonlinear interfacial stiffness. This approach is inconvenient for the study of machine elements where only one side of the interface is accessible. In this study a reflection method is undertaken, and the results are compared to existing experimental work with through transmission. The variation of both linear and nonlinear interfacial stiffnesses was measured as the nominal contact pressure was increased. In both cases interfacial stiffness was expressed as nonlinear differential equations and solved to deduce the contact pressure-relative surface approach relationships. The relationships derived from linear and nonlinear measurements were similar, indicating the validity of the presented methods.

Ultrasonic Test on Recycled Concrete: Relationship among Ultrasonic Waves Velocity, Compressive Strength and Elastic Modulus

2014 ◽  
Vol 894 ◽  
pp. 45-49 ◽  
Author(s):  
Luisa Pani ◽  
Lorena Francesconi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Ultrasonic Wave ◽  
Ultrasonic Test ◽  
Ultrasonic Waves ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Static Modulus ◽  
Cylindrical Samples

In this paper an experimental program has been carried out in order to compare compressive strength fcand elastic static modulus Ecof recycled concrete with ultrasonic waves velocity Vp, to establish the possibility of employing nondestructive ultrasonic tests to qualify recycled concrete. 9 mix of concrete with different substitution percentage of recycled aggregates instead of natural ones and 27 cylindrical samples have been made. At first ultrasonic tests have been carried out on cylindrical samples, later elastic static modulus Ecand compressive strength fchave been experimentally evaluated. The dynamic elastic modulus Edhas been determined in function of ultrasonic wave velocity Vp; furthermore the correlations among Ed, Ec, fce Vphave been determined. It has been demonstrated that ultrasonic tests are suitable for evaluating different deformative and resisting concrete performances even when variations are small.

scholarly journals High Frequency Ultrasonic Wave Propagation in  Anisotropic Materials

2021 ◽  
Author(s):  
◽  
Andrew Paul Dawson
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
High Frequency ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Tissue Characterisation ◽  
Ultrasonic Wave Propagation ◽  
Matching Layer ◽  
Fibrous Tissues ◽  
Wave Modes

<p>The influence of highly regular, anisotropic, microstructured materials on high frequency ultrasonic wave propagation was investigated in this work. Microstructure, often only treated as a source of scattering, significantly influences high frequency ultrasonic waves, resulting in unexpected guided wave modes. Tissues, such as skin or muscle, are treated as homogeneous by current medical ultrasound systems, but actually consist of highly anisotropic micron-sized fibres. As these systems increase towards 100 MHz, these fibres will significantly influence propagating waves leading to guided wave modes. The effect of these modes on image quality must be considered. However, before studies can be undertaken on fibrous tissues, wave propagation in more ideal structures must be first understood. After the construction of a suitable high frequency ultrasound experimental system, finite element modelling and experimental characterisation of high frequency (20-200 MHz) ultrasonic waves in ideal, collinear, nanostructured alumina was carried out. These results revealed interesting waveguiding phenomena, and also identified the potential and significant advantages of using a microstructured material as an alternative acoustic matching layer in ultrasonic transducer design. Tailorable acoustic impedances were achieved from 4-17 MRayl, covering the impedance range of 7-12 MRayl most commonly required by transducer matching layers. Attenuation coefficients as low as 3.5 dBmm-1 were measured at 100 MHz, which is excellent when compared with 500 dBmm-1 that was measured for a state of the art loaded epoxy matching layer at the same frequency. Reception of ultrasound without the restriction of critical angles was also achieved, and no dispersion was observed in these structures (unlike current matching layers) until at least 200 MHz. In addition, to make a significant step forward towards high frequency tissue characterisation, novel microstructured poly(vinyl alcohol) tissue-mimicking phantoms were also developed. These phantoms possessed acoustic and microstructural properties representative of fibrous tissues, much more realistic than currently used homogeneous phantoms. The attenuation coefficient measured along the direction of PVA alignment in an example phantom was 8 dBmm-1 at 30 MHz, in excellent agreement with healthy human myocardium. This method will allow the fabrication of more realistic and repeatable phantoms for future high frequency tissue characterisation studies.</p>

DESIGN, CONSTRUCTION AND TESTING OF A SMART STATIC AND DYNAMIC OBSTACLE WALKING STICK WITH EMF DETECTOR FOR THE BLINDS USING MCU AND CONTROLLING SOFTWARE

2021 ◽  
Vol 5 (2) ◽  
pp. 334-343
Author(s):  
Sani Abdullahi Adamu ◽  
Abdulkarim Adamu ◽  
M. S. Anas
Keyword(s):  
Electromagnetic Waves ◽  
Ultrasonic Waves ◽  
Project Work ◽  
Electrical Safety ◽  
Blind People ◽  
Visually Challenged ◽  
Dynamic Obstacle ◽  
Walking Stick ◽  
Modern Technologies ◽  
Design Construction

Smart static and dynamic obstacle walking stick with EMF detector is an upgraded smart stick designed for blind people for optimal navigation and electrical safety.  An advanced blind stick prototype that allows visually challenged people to navigate walking paths and identify electronic gadgets with ease using modern technologies is hereby developed. The blind stick is integrated with ultrasonic sensor along with an EMF detector. This prototype first uses ultrasonic sensors to sense obstacles ahead using ultrasonic waves. On sensing obstacles, the sensor directs this data to the microcontroller. The microcontroller then processes this data and examine if the obstacle is close enough. If the obstacle is not that close the circuit does nothing. If the obstacle is close the microcontroller sends a signal to sound a buzzer. One more feature is that it allows the blind to detect the presence of EMF (electromagnetic field/electromagnetic waves) in the region he/she is, if there is, the microcontroller also sends a signal to a vibration motor (i.e. the output is in form of vibration), and if otherwise, the circuit does not trigger and thus, the vibration motor does nothing. The results obtained from the measurements have shown that this project work is optimally working and indeed operative.

Rock-physics modeling of ultrasonic P- and S-wave attenuation in partially frozen brine and unconsolidated sand systems and comparison with laboratory measurements

Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. MR153-MR171 ◽  
Author(s):  
Linsen Zhan ◽  
Jun Matsushima
Keyword(s):  
Ultrasonic Wave ◽  
Wave Attenuation ◽  
Freezing Point ◽  
Rock Physics ◽  
Ultrasonic Waves ◽  
P Wave ◽  
Dominant Factor ◽  
S Wave ◽  
High Attenuation ◽  
Unconsolidated Sand

The nonintuitive observation of the simultaneous high velocity and high attenuation of ultrasonic waves near the freezing point of brine was previously measured in partially frozen systems. However, previous studies could not fully elucidate the attenuation variation of ultrasonic wave propagation in a partially frozen system. We have investigated the potential attenuation mechanisms responsible for previously obtained laboratory results by modeling ultrasonic wave transmission in two different partially frozen systems: partially frozen brine (two phases composed of ice and unfrozen brine) and unconsolidated sand (three phases composed of ice, unfrozen brine, and sand). We adopted two different rock-physics models: an effective medium model for partially frozen brine and a three-phase extension of the Biot model for partially frozen unconsolidated sand. For partially frozen brine, our rock-physics study indicated that squirt flow caused by unfrozen brine inclusions in porous ice could be responsible for high P-wave attenuation around the freezing point. Decreasing P-wave attenuation below the freezing point can be explained by the gradual decrease of squirt flow due to the gradual depletion of unfrozen brine. For partially frozen unconsolidated sand, our rock-physics study implied that squirt flow between ice grains is a dominant factor for P-wave attenuation around the freezing point. With decreasing temperature lower than the freezing point, the friction between ice and sand grains becomes more dominant for P-wave attenuation because the decreasing amount of unfrozen brine reduces squirt flow between ice grains, whereas the generation of ice increases the friction. The increasing friction between ice and sand grains caused by ice formation is possibly responsible for increasing the S-wave attenuation at decreasing temperatures. Then, further generation of ice with further cooling reduces the elastic contrast between ice and sand grains, hindering their relative motion; thus, reducing the P- and S-wave attenuation.

Study on Damage Mechanism of Pipe Using Ultrasonic Wave and Acoustic Emission Technique

2007 ◽  
Vol 353-358 ◽  
pp. 2415-2418
Author(s):  
Jin Kyung Lee ◽  
Sang Ll Lee ◽  
Joon Hyun Lee
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Ultrasonic Wave ◽  
Guided Waves ◽  
Damage Mechanism ◽  
Ultrasonic Waves ◽  
Steel Pipe ◽  
Thin Wall ◽  
Acoustic Emission Technique ◽  
Velocity Transmission

A study on corrosion evaluation by using ultrasonic waves and acoustic emission technique is presented. The experimental equipment was established to improve the corrosion process of carbon steel pipe. The carbon steel pipe was under 473K temperatures and 10Mpa pressure conditions, and ultrasonic wave and acoustic emission techniques were used to inspect the degree of corrosion after a certain period of time. Ultrasonic bulk waves are limited by the poor time resolution when used in the measurement of corrosion depth in thin wall structures because the corroded surfaces cause unclear echo signal edges. Therefore, in this study, the ultrasonic guided waves were generated on the pipe because the thickness of pipe was thin. Various wave modes were subsequently generated on the pipe to evaluate the implications of corrosion thinning on group velocity, transmission and reflection amplitudes. The amplitudes of the transmitted and the reflected waves are influenced by couplent material. In order to reduce the effect of coupling acoustic emission sensor was used. Acoustic emission technique has lots of parameters to evaluate the corrosion besides amplitude parameter. Among parameters energy, count, and frequency were useful parameters to measure the degree of corrosion inside the carbon steel pipe under 473K temperatures.

Laboratory experiments on compressional ultrasonic wave attenuation in partially frozen brines

Geophysics ◽  
2008 ◽  
Vol 73 (2) ◽  
pp. N9-N18 ◽  
Author(s):  
Jun Matsushima ◽  
Makoto Suzuki ◽  
Yoshibumi Kato ◽  
Takao Nibe ◽  
Shuichi Rokugawa
Keyword(s):  
Ultrasonic Wave ◽  
Laboratory Experiments ◽  
Wave Attenuation ◽  
Ultrasonic Attenuation ◽  
Liquid System ◽  
Seismic Attenuation ◽  
Ultrasonic Waves ◽  
Frequency Range ◽  
Pore Microstructure ◽  
Solid Liquid

Often, the loss mechanisms responsible for seismic attenuation are unclear and controversial. We used partially frozen brine as a solid-liquid coexistence system to investigate attenuation phenomena. Ultrasonic wave-transmission measurements on an ice-brine coexisting system were conducted to examine the influence of unfrozen brine in the pore microstructure on ultrasonic waves. We observed the variations of a 150–1000 kHz wave transmitted through a liquid system to a solid-liquid coexistence system, changing its temperature from [Formula: see text] to –[Formula: see text]. We quantitatively estimated attenuation in a frequency range of [Formula: see text] by considering different distances between the source and receiver transducers. We also estimated the total amount of frozen brine at each temperature by using the pulsed nuclear magnetic resonance (NMR) technique and related those results to attenuation results. The waveform analyses indicate that ultrasonic attenuation in an ice-brine coexisting system reaches its peak at [Formula: see text], at which the ratio of the liquid phase to the total volume in an ice-brine coexisting system is maximal. Finally, we obtained a highly positive correlation between the attenuation of ultrasonic waves and the total amount of unfrozen brine. Thus, laboratory experiments demonstrate that ultrasonic waves within this frequency range are affected significantly by the existence of unfrozen brine in the pore microstructure.

Synthesis of Spherical SrCO3 Powders by Ultrasonic Waves

2012 ◽  
Vol 535-537 ◽  
pp. 301-304
Author(s):  
Mi Xiang Qi ◽  
Jia Sheng Li ◽  
Shu Xuan Wang ◽  
Zhan Shou Yang ◽  
Shu Ya Wang ◽  
...  
Keyword(s):  
Ultrasonic Wave ◽  
Average Particle Size ◽  
Strontium Carbonate ◽  
Ultrasonic Waves ◽  
Average Particle ◽  
Reaction Parameters ◽  
Reaction Conditions ◽  
Spherical Structure ◽  
High Dispersity ◽  
Novel Method

A new synthetic technology of Strontium carbonate with ultrasonic is introduced in this article. Ultrasonic wave synthetic technology is a fast and novel method. Spherical SrCO3 powders were synthesized by changing the solvent and reaction conditions using the ultrasonic wave method. The SrCO3 powders were characterized by the XRD and SEM.The results show that the asprepared products were Spherical structure and with high dispersity, the average particle size of the SrCO3 powders synthesized by the ultrasonic wave synthetic technology is 0.3nm~ 0.5nm. Some reaction parameters were investigated during the process.

scholarly journals Transition Time of Ultrasonic Wave as a Tool of Quality Evaluation of Layered Polymer Composites

2017 ◽  
Vol 42 (3) ◽  
pp. 499-506 ◽  
Author(s):  
Małgorzata Szymiczek
Keyword(s):  
Polymer Composites ◽  
Ultrasonic Wave ◽  
Quality Evaluation ◽  
Bending Strength ◽  
Physical Nature ◽  
Ultrasonic Waves ◽  
Transition Time ◽  
Material Structure ◽  
Sound Waves ◽  
Layered Polymer Composites

AbstractObservation of behaviour phenomena of ultrasonic waves in an object allows for quality assessment, identification and location of discontinuity. Physical nature of acoustic processes is based on propagation of mechanical waves constituting a disturbance of equilibrium of the state of material. The acoustic process identified by selected characteristics can be a source of information about state of material, its structure, and properties, which is particularly important for systems exhibiting anisotropy properties, and such are layered polymer composites. They are special materials because their properties depend greatly on the manufacturing technology. Therefore, while conducting acoustic tests which use the influence of elastic properties and homogeneity of material structure for propagation of sound waves the adopted method of measuring characteristics which identifies propagation of ultrasonic wave phenomenon is of particular importance. The aim of the work was quality evaluation of layered polymer composites made by winding and press moulding by the method of echo and C-scan, using head Phased Array. Composites have been tested by thermal and fatigue degradation. Quality evaluation has been made based on the transition time of the ultrasonic wave and the bending strength.

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