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laser doppler vibrometer

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https://www.readbyqxmd.com/read/27857289/use-of-photoacoustic-excitation-and-laser-vibrometry-to-remotely-detect-trace-explosives
#1
C M Wynn, R W Haupt, J H Doherty, R R Kunz, W Bai, G Diebold
In this paper, we examine a laser-based approach to remotely initiate, measure, and differentiate acoustic and vibrational emissions from trace quantities of explosive materials against their environment. Using a pulsed ultraviolet laser (266 nm), we induce a significant (>100  Pa) photoacoustic response from small quantities of military-grade explosives. The photoacoustic signal, with frequencies predominantly between 100 and 500 kHz, is detected remotely via a wideband laser Doppler vibrometer. This two-laser system can be used to rapidly detect and discriminate explosives from ordinary background materials, which have significantly weaker photoacoustic response...
November 10, 2016: Applied Optics
https://www.readbyqxmd.com/read/27631663/intracranial-pressure-and-promontory-vibration-with-soft-tissue-stimulation-in-cadaveric-human-whole-heads
#2
Christof Roosli, Ivo Dobrev, Jae Hoon Sim, Rahel Gerig, Flurin Pfiffner, Stefan Stenfelt, Alexander M Huber
HYPOTHESIS: Intracranial pressure and skull vibrations are correlated and depend on the stimulation position and frequency. BACKGROUND: A hearing sensation can be elicited by vibratory stimulation on the skin covered skull, or by stimulation on soft tissue such as the neck. It is not fully understood whether different stimulation sites induce the skull vibrations responsible for the perception or whether other transmission pathways are dominant. The aim of this study was to assess the correlation between intracranial pressure and skull vibration measured on the promontory for stimulation to different sites on the head...
October 2016: Otology & Neurotology
https://www.readbyqxmd.com/read/27594098/a-tri-coil-bellows-type-round-window-transducer-with-improved-frequency-characteristics-for-middle-ear-implants
#3
Dong Ho Shin, Ki Woong Seong, Sunil Puria, Kyu-Yup Lee, Jin-Ho Cho
A number of methods to drive the round window (RW) using a floating mass transducer (FMT) have been reported. This method has attracted attention because the FMT is relatively easy to implant in the RW niche. However, the use of an FMT to drive the RW has been proven to produce low outputs at frequencies below approximately 1 kHz. In this study, a new tri-coil bellows-type transducer (TCBT), which has excellent low frequency output and is easy to implant, is proposed. To design the frequency characteristics of the TCBT, mechanical and electrical simulations were performed, and then a comparative analysis was conducted between a floating mass type transducer (like the FMT) and a fixed type transducer (like the TCBT)...
September 2, 2016: Hearing Research
https://www.readbyqxmd.com/read/27557194/photo-vibrational-spectroscopy-of-solid-and-liquid-chemicals-using-laser-doppler-vibrometer
#4
Qi Hu, Jacob Song Kiat Lim, Huan Liu, Yu Fu
Photoacoustic/photothermal spectroscopy is an established technique for trace detection of chemicals and explosives. However, prior sample preparation is required and the analysis is conducted in a sealed space with a high-sensitivity microphone or a piezo sensor coupled with a lock-in amplifier, limiting the technique to applications in a laboratory environment. Due to the aforementioned requirements, traditionally this technique may not be suitable for defense and security applications where the detection of explosives or hazardous chemicals is required in an open environment at a safe standoff distance...
August 22, 2016: Optics Express
https://www.readbyqxmd.com/read/27475551/development-of-an-fpga-based-multipoint-laser-pyroshock-measurement-system-for-explosive-bolts
#5
Syed Haider Abbas, Jae-Kyeong Jang, Jung-Ryul Lee, Zaeill Kim
Pyroshock can cause failure to the objective of an aerospace structure by damaging its sensitive electronic equipment, which is responsible for performing decisive operations. A pyroshock is the high intensity shock wave that is generated when a pyrotechnic device is explosively triggered to separate, release, or activate structural subsystems of an aerospace architecture. Pyroshock measurement plays an important role in experimental simulations to understand the characteristics of pyroshock on the host structure...
July 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27473506/acoustic-input-impedance-of-the-avian-inner-ear-measured-in-ostrich-struthio-camelus
#6
Pieter G G Muyshondt, Peter Aerts, Joris J J Dirckx
In both mammals and birds, the mechanical behavior of the middle ear structures is affected by the mechanical impedance of the inner ear. In this study, the aim was to quantify the acoustic impedance of the avian inner ear in the ostrich, which allows us to determine the effect on columellar vibrations and middle ear power flow in future studies. To determine the inner ear impedance, vibrations of the columella were measured for both the quasi-static and acoustic stimulus frequencies. In the frequency range of 0...
September 2016: Hearing Research
https://www.readbyqxmd.com/read/27461115/vibration-transmission-through-sheet-webs-of-hobo-spiders-eratigena-agrestis-and-tangle-webs-of-western-black-widow-spiders-latrodectus-hesperus
#7
Samantha Vibert, Catherine Scott, Gerhard Gries
Web-building spiders construct their own vibratory signaling environments. Web architecture should affect signal design, and vice versa, such that vibratory signals are transmitted with a minimum of attenuation and degradation. However, the web is the medium through which a spider senses both vibratory signals from courting males and cues produced by captured prey. Moreover, webs function not only in vibration transmission, but also in defense from predators and the elements. These multiple functions may impose conflicting selection pressures on web design...
November 2016: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/27428980/nanomechanical-pyrolytic-carbon-resonators-novel-fabrication-method-and-characterization-of-mechanical-properties
#8
Maksymilian Kurek, Frederik K Larsen, Peter E Larsen, Silvan Schmid, Anja Boisen, Stephan S Keller
Micro- and nanomechanical string resonators, which essentially are highly stressed bridges, are of particular interest for micro- and nanomechanical sensing because they exhibit resonant behavior with exceptionally high quality factors. Here, we fabricated and characterized nanomechanical pyrolytic carbon resonators (strings and cantilevers) obtained through pyrolysis of photoresist precursors. The developed fabrication process consists of only three processing steps: photolithography, dry etching and pyrolysis...
2016: Sensors
https://www.readbyqxmd.com/read/27403641/wave-mode-extraction-from-multimodal-wave-signals-in-an-orthotropic-composite-plate
#9
M Ratassepp, Z Fan, K Lasn
In this paper the post-processing procedure based on the mode orthogonality is applied to extract individual waveforms at a composite plate edge from multimodal signals. To obtain the amplitudes of individual modes, numerically predicted modal through-thickness stress and displacement field values are used in the orthogonality relation. The performance of the mode extraction technique is evaluated by processing signals obtained from Finite Element (FE) modeling and experimental measurements. The propagation of the overlapping wave packets of Lamb modes S0 and A0 is considered along the fiber direction and perpendicular to that direction...
September 2016: Ultrasonics
https://www.readbyqxmd.com/read/27347955/experimental-analysis-of-bisbenzocyclobutene-bonded-capacitive-micromachined-ultrasonic-transducers
#10
Rayyan Manwar, Sazzadur Chowdhury
Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding...
2016: Sensors
https://www.readbyqxmd.com/read/27229753/2-d-steering-and-propelling-of-acoustic-bubble-powered-microswimmers
#11
Jian Feng, Junqi Yuan, Sung Kwon Cho
This paper describes bi-directional (linear and rotational) propelling and 2-D steering of acoustic bubble-powered microswimmers that are achieved in a centimeter-scale pool (beyond chip level scale). The core structure of a microswimmer is a microtube with one end open in which a gaseous bubble is trapped. The swimmer is propelled by microstreaming flows that are generated when the trapped bubble is oscillated by an external acoustic wave. The bubble oscillation and thus propelling force are highly dependent on the frequency of the acoustic wave and the bubble length...
June 21, 2016: Lab on a Chip
https://www.readbyqxmd.com/read/27206397/a-new-malleostapedotomy-prosthesis-experimental-analysis-by-laser-doppler-vibrometer-in-fresh-cadaver-temporal-bones
#12
Luis A Vallejo, María T Manzano, Antonio Hidalgo, Alberto Hernández, Juan Sabas, Hugo Lara, Elisa Gil-Carcedo, David Herrero
INTRODUCTION AND OBJECTIVES: One of the problems with total ossicular replacement prostheses is their stability. Prosthesis dislocations and extrusions are common in middle ear surgery. This is due to variations in endo-tympanic pressure as well as design defects. The design of this new prosthesis reduces this problem by being joined directly to the malleus handle. The aim of this study is to confirm adequate acoustic-mechanical behaviour in fresh cadaver middle ear of a new total ossicular replacement prosthesis, designed using the finite elements method...
May 17, 2016: Acta Otorrinolaringológica Española
https://www.readbyqxmd.com/read/27041338/fully-implantable-hearing-aid-in-the-incudostapedial-joint-gap
#13
Martin Koch, Till Moritz Eßinger, Thomas Stoppe, Nikoloz Lasurashvili, Matthias Bornitz, Thomas Zahnert
A fully implantable hearing aid is introduced which is a combined sensor-actuator-transducer designed for insertion into the incudostapedial joint gap (ISJ). The active elements each consist of a thin titanium membrane with an applied piezoelectric single crystal. The effectiveness of the operating principle is verified in a temporal bone study. We also take a closer look at the influence of an implantation-induced increase in middle ear stiffness on the transducer's output. An assembly of the transducer with 1 mm thickness is built and inserted into six temporal bones...
March 31, 2016: Hearing Research
https://www.readbyqxmd.com/read/27020274/performance-of-the-round-window-soft-coupler-for-the-backward-stimulation-of-the-cochlea-in-a-temporal-bone-model
#14
Antoniu-Oreste Gostian, David Schwarz, Philipp Mandt, Andreas Anagiotos, Magdalene Ortmann, David Pazen, Dirk Beutner, Karl-Bernd Hüttenbrink
The round window vibroplasty is a feasible option for the treatment of conductive, sensorineural and mixed hearing loss. Although clinical data suggest a satisfying clinical outcome with various coupling methods, the most efficient coupling technique of the floating mass transducer to the round window is still a matter of debate. For this, a soft silicone-made coupler has been developed recently that aims to ease and optimize the stimulation of the round window membrane of this middle ear implant. We performed a temporal bone study evaluating the performance of the soft coupler compared to the coupling with individually shaped cartilage, perichondrium and the titanium round window coupler with loads up to 20 mN at the unaltered and fully exposed round window niche...
March 28, 2016: European Archives of Oto-rhino-laryngology
https://www.readbyqxmd.com/read/26972795/first-results-of-a-novel-adjustable-length-ossicular-reconstruction-prosthesis-in-temporal-bones
#15
Peter K Gottlieb, Xiping Li, Ashkan Monfared, Nikolas Blevins, Sunil Puria
OBJECTIVES/HYPOTHESIS: The performance of an ossicular replacement prosthesis (ORP) is influenced by its alignment and appropriate tension between the tympanic membrane and the stapes footplate. A novel ORP with a flexible element that potentially allows for length adjustment in situ is presented and tested for acoustic performance. STUDY DESIGN: Laser Doppler vibrometry in fresh human cadaveric temporal bones was used to test the acoustic performance of the adjustable ORP relative to standard prostheses used for ossiculoplasty...
November 2016: Laryngoscope
https://www.readbyqxmd.com/read/26913508/shaking-youngsters-and-shaken-adults-female-beetles-eavesdrop-on-larval-seed-vibrations-to-make-egg-laying-decisions
#16
Raul Narciso C Guedes, Jayne E Yack
Egg-laying decisions are critical for insects, and particularly those competing for limited resources. Sensory information used by females to mediate egg-laying decisions has been reported to be primarily chemical, but the role of vibration has received little attention. We tested the hypothesis that vibrational cues produced by feeding larvae occupying a seed influences egg-laying decisions amongst female cowpea beetles. This hypothesis is supported by three lines of evidence using two strains of the cowpea beetle (Callosobruchus maculatus), an Indian strain with choosy females and aggressively competing larvae and a Brazilian strain with less choosy females and larvae exhibiting an "accommodating" type of competition...
2016: PloS One
https://www.readbyqxmd.com/read/26909175/a-comprehensive-study-of-the-delay-vector-variance-method-for-quantification-of-nonlinearity-in-dynamical-systems
#17
V Jaksic, D P Mandic, K Ryan, B Basu, V Pakrashi
Although vibration monitoring is a popular method to monitor and assess dynamic structures, quantification of linearity or nonlinearity of the dynamic responses remains a challenging problem. We investigate the delay vector variance (DVV) method in this regard in a comprehensive manner to establish the degree to which a change in signal nonlinearity can be related to system nonlinearity and how a change in system parameters affects the nonlinearity in the dynamic response of the system. A wide range of theoretical situations are considered in this regard using a single degree of freedom (SDOF) system to obtain numerical benchmarks...
January 2016: Royal Society Open Science
https://www.readbyqxmd.com/read/26907891/guided-wave-phased-array-beamforming-and-imaging-in-composite-plates
#18
Lingyu Yu, Zhenhua Tian
This paper describes phased array beamforming using guided waves in anisotropic composite plates. A generic phased array algorithm is presented, in which direction dependent guided wave parameters and the energy skew effect are considered. This beamforming at an angular direction is achieved based on the classic delay-and-sum principle by applying phase delays to signals received at array elements and adding up the delayed signals. The phase delays are determined with the goal to maximize the array output at the desired direction and minimize it otherwise...
May 2016: Ultrasonics
https://www.readbyqxmd.com/read/26773789/three-dimensional-image-based-simulation-of-ultrasonic-wave-propagation-in-polycrystalline-metal-using-phase-field-modeling
#19
K Nakahata, H Sugahara, M Barth, B Köhler, F Schubert
When modeling ultrasonic wave propagation in metals, it is important to introduce mesoscopic crystalline structures because the anisotropy of the crystal structure and the heterogeneity of grains disturb ultrasonic waves. In this paper, a three-dimensional (3D) polycrystalline structure generated by multiphase-field modeling was introduced to ultrasonic simulation for nondestructive testing. 3D finite-element simulations of ultrasonic waves were validated and compared with visualization results obtained from laser Doppler vibrometer measurements...
April 2016: Ultrasonics
https://www.readbyqxmd.com/read/26705603/an-electromechanical-coupling-model-of-a-bending-vibration-type-piezoelectric-ultrasonic-transducer
#20
Qiang Zhang, Shengjun Shi, Weishan Chen
An electromechanical coupling model of a bending vibration type piezoelectric ultrasonic transducer is proposed. The transducer is a Langevin type transducer which is composed of an exponential horn, four groups of PZT ceramics and a back beam. The exponential horn can focus the vibration energy, and can enlarge vibration amplitude and velocity efficiently. A bending vibration model of the transducer is first constructed, and subsequently an electromechanical coupling model is constructed based on the vibration model...
March 2016: Ultrasonics
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