Search results for: acoustic trap

Authors: Kyle Saltmarsh

Abstract:

Acoustic testing possesses many benefits due to its non-destructive nature and practicality. There hence exists many scenarios in which using acoustic testing for condition testing shows powerful feasibility. A wealth of information is contained within the acoustic and vibration characteristics of structures, allowing the development meaningful features for the classification of their respective condition. In this paper, methods, results, and discussions are presented on the use of non-destructive acoustic testing coupled with acoustic feature extraction and machine learning techniques for the condition testing of manufactured circular steel plates subjected to varied levels of damage.

Keywords: plates, deformation, acoustic features, machine learning

Procedia PDF Downloads 337

Authors: Sudabe Amini, Jamasb Nozari, Somaye Rahimi

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Bark beetles are one of the most destructive groups of pests in the forest and green space. Mediterranean pine Engraver Orthotomicus erosus (Wollston) is the dominant species in the pine forests of Iran. Pine forests are considered a crucial region in the world and need high protection. Although there is no effective control method, mass trapping is the most common method to suppress the bark beetle population. Due to this, from 2018-to 2020, a survey was conducted on bark beetles mass trapping by using two kinds of traps, including pheromone and tree trap. These traps were evaluated in 10 different sites of pine forests. The statistical results proved that significant differences between the pheromone trap and tree trap were observed. It confirmed that the pheromone trap attracted more beetles than the tree trap. The results of this study suggest that the most effective and applicable method in bark beetle’s management of pines forest is using a pheromone trap that suppresses and maintains bark beetle’s population at an economic level, although tree traps attract bark beetles too. In the future, using tree-pheromone traps, which would synergist attraction of more bark beetles, is recommended.

Keywords: bark beetle, pines forest, Orthotomicus erosus, pheromone trap, tree trap

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Authors: Amna Jalal, Muhammad Dildar Gogi, Muhammad Jalal Arif, Anum Tariq, Waleed Afzal Naveed, Talha Farooq, Mubashir Iqbal, Muhammad Junaid Nisar

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Melon fruit flies (Diptera: Tephritidae: Dacinae) are economically important pests of the cucurbits and are geographically distributed throughout the tropics and subtropics of the world. It causes heavy quantitative and qualitative losses in bitter gourd. The present experiment was carried out to evaluate the performance of different biodegradable waxes based SPLAT-MAT-CL (Specialized Pheromone and Lure Application Technology-Male Anhelation Technique- Cue Lure) formulations in bitter gourd field. Fourteen SPLAT-MAT emulsions/formulations were prepared by admixing different SPLAT matrices with toxicant (spinosad) and sex pheromone cuelure (attractant) in different proportionate percentage by weight. The results revealed that attraction and trapping of fruit flies of B. cucurbitae varied significantly for different SPLAT-MAT-CL formulations (p < 0.05). The maximum B. cucurbitae males were trapped in SPLAT-MAT-CL-7 (60 flies/trap/day) followed by SPLAT-MAT-CL-9 (40 flies/trap/day). The performance of all other formulations of SPLAT-MAT-CL was found in the order of SPLAT-MAT-CL-8 (30 flies/trap/day) > SPLAT-MAT-CL-3 (28 flies/trap/day) > SPLAT-MAT-CL-5 (25 flies/trap/day) > SPLAT-MAT-CL-4 (22 flies/trap/day) > SPLAT-MAT-CL-12 (20 flies/trap/day) SPLAT-MAT-CL-2 (19 flies/trap/day) > SPLAT-MAT-CL-14 (17 flies/trap/day) > SPLAT-MAT-CL-13 (15 flies/trap/day) > SPLAT-MAT-CL-11 (10 flies/trap/day) > SPLAT-MAT-CL-1 (8 flies/trap/day) > SPLAT-MAT-CL-10 (02 flies/trap/day). Overall, all the SPLAT-MAT-CL formulations, except SPLAT-MAT-CL-10, demonstrated higher density of captures of B. cucurbitae males as compared to standard (06 flies/trap/day). The results also demonstrate that SPLAT-MAT-CL-7, SPLAT-MAT-CL-9, SPLAT-MAT-CL-8, SPLAT-MAT-CL-3, SPLAT-MAT-CL-5, SPLAT-MAT-CL-4, SPLAT-MAT-CL-12, SPLAT-MAT-CL-2, SPLAT-MAT-CL-14, SPLAT-MAT-CL-13, SPLAT-MAT-CL-11 and SPLAT-MAT-CL-1 explained approximately 5, 4.6, 4.1, 3.6, 3.3, 3.1,2.8,2.5 and 1.6 times higher captures of B. cucurbitae males over standards. However, SPLAT-MAT-CL-10 demonstrated 3 times fewer captures of B. cucurbitae males over standards. In conclusion, SPLAT-MAT-CL-7, SPLAT-MAT-CL-9 can be exploited for the monitoring and trapping of B. cucurbitae in its IPM of program.

Keywords: attractancy, field conditions, melon fruit fly, SPLAT-MAT-CL

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Authors: Deepak K. Gupta, T. R. Ravindran

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Holographic Optical Tweezers (HOTs) in general use iterative algorithms such as weighted Gerchberg-Saxton (WGS) to generate multiple traps, which produce traps with 99% uniformity theoretically. But in experiments, it is the phase response of the spatial light modulator (SLM) which ultimately determines the efficiency, uniformity, and quality of the trap spots. In general, SLMs show a nonlinear phase response behavior, and they may even have asymmetric phase modulation depth before and after π. This affects the resolution with which the gray levels are addressed before and after π, leading to a degraded trap performance. We present a method to optimize the SLM for a linear phase response behavior along with a symmetric phase modulation depth around π. Further, we optimize the SLM for its varying phase response over different spatial regions by optimizing the brightness/contrast and gamma of the hologram in different subsections. We show the effect of the optimization on an array of trap spots resulting in improved efficiency and uniformity. We also calculate the spot sharpness metric and trap performance metric and show a tightly focused spot with reduced aberration. The trap performance is compared by calculating the trap stiffness of a trapped particle in a given trap spot before and after aberration correction. The trap stiffness is found to improve by 200% after the optimization.

Keywords: spatial light modulator, optical trapping, aberration, phase modulation

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Authors: Hafdaoui Hichem, Mehadjebia Cherifa, Benatia Djamel

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In this paper, we propose a new method for Bulk detection of an acoustic microwave signal during the propagation of acoustic microwaves in a piezoelectric substrate (Lithium Niobate LiNbO3). We have used the classification by probabilistic neural network (PNN) as a means of numerical analysis in which we classify all the values of the real part and the imaginary part of the coefficient attenuation with the acoustic velocity in order to build a model from which we note the Bulk waves easily. These singularities inform us of presence of Bulk waves in piezoelectric materials. By which we obtain accurate values for each of the coefficient attenuation and acoustic velocity for Bulk waves. This study will be very interesting in modeling and realization of acoustic microwaves devices (ultrasound) based on the propagation of acoustic microwaves.

Keywords: piezoelectric material, probabilistic neural network (PNN), classification, acoustic microwaves, bulk waves, the attenuation coefficient

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Authors: Bruna G. M. Araújo, Pedro M. M. Q. Cruz

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In this letter, we review the literature of the major concepts that govern Gaussian quantum information. As we work with quantum information and computation with continuous variables, Gaussian states are needed to better describe these systems. Analyzing a single ion locked in a Paul trap we use the interaction picture to obtain a toolbox of Gaussian operations with the ion-laser interaction Hamiltionian. This is achieved exciting the ion through the combination of two lasers of distinct frequencies corresponding to different sidebands of the external degrees of freedom. First we study the case of a trap with 1 mode and then the case with 2 modes. In this way, we achieve different continuous variables gates just by changing the external degrees of freedom of the trap and combining the Hamiltonians of blue and red sidebands.

Keywords: Paul trap, ion-laser interaction, Gaussian operations

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Authors: Laboratory of Semiconducting, Metallic Materials (LMSM) Biskra Algeria

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InZnSnO2 (IZTO)/β-Ga2O3 Schottky solar barrier photodetector (PhD) exposed to 255 nm was simulated and compared to the measurement. Numerical simulations successfully reproduced the photocurrent at reverse bias and response by taking into account several factors, such as conduction mechanisms and material parameters. By adopting reducing the density of the trap as an improvement. The effect of reducing the bulk trap densities on the photocurrent, response, and time-dependent (continuous conductivity) was studied. As the trap density decreased, the photocurrent increased. The response was 0.04 A/W for the low Ga2O3 trap density. The estimated decay time for the lowest intensity ET (0.74, 1.04 eV) is 0.05 s and is shorter at ∼0.015 s for ET (0.55 eV). This indicates that the shallow traps had the dominant effect (ET = 0.55 eV) on the continuous photoconductivity phenomenon. Furthermore, with decreasing trap densities, this PhD can be considered as a self-powered solar-blind photodiode (SBPhD).

Keywords: IZTO/β-Ga2O3, self-powered solar-blind photodetector, numerical simulation, bulk traps

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Authors: Sanjit Kumar Paul, A. A. Mamun, M. R. Amin

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The Linear propagation of the dust-acoustic wave in a dusty plasma consisting of Boltzmann distributed electrons and ions and mobile charge fluctuating positive dust grains has been investigated by employing the reductive perturbation method. It has been shown that the dust charge fluctuation is a source of dissipation and its responsible for the formation of the dust-acoustic waves in such a dusty plasma. The basic features of such dust-acoustic waves have been identified. It has been proposed to design a new laboratory experiment which will be able to identify the basic features of the dust-acoustic waves predicted in this theoretical investigation.

Keywords: dust acoustic waves, dusty plasma, Boltzmann distributed electrons, charge fluctuation

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Authors: Pisit Poolprasert, Phakin Kubchanan, Keerati Tanruean, Wisanu Thongchai, Yuttasak Chammui, Wirot Likittrakulwong

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Rice insect pests are problems to rice production. Use of chemicals to minimize these problems of insect pests in paddy field can lead to the residue and affect the health of farmers. Therefore, botanical extracts applied for controlling rice serious enemies should be promoted especially use of plant extract as attractants to lure insects. This research aimed to feasibility study of bioattractants from pandanus palm extracts for trapping insect pets using two different trap models, including plastic bottle and yellow sticky traps. Two main growth and development stages of rice, namely tillering and booting stages, were selected and trapped. The results from both trap models revealed that four rice insect species, including Orseolia oryzae (Wood-Mason), Nilaparvata lugens, Recilia dorsalis, and Nephotettix nigropictus from three families (Cecidomyiidae, Cicadellidae and Delphacidae) and two main orders (Diptera and Hemiptera) were exhibited. All rice insect species mentioned could be found from the yellow sticky trap that were higher than in the bottle trap in which only O. oryzae could be only trapped. From this survey, it was indicated that the yellow sticky trap coated with pandanus palm extracts had a promising potential to use as an attractant for the detection of rice paddy insects in the next future.

Keywords: pandanus palm, bioattractant, bottle trap, yellow sticky trap

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Authors: Motonori Tamura

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The hydrogen barrier properties of the coatings of diamond-like carbon (DLC) were evaluated. Using plasma chemical vapor deposition and sputtering, DLC coatings were deposited on Type 316L stainless steels. The hydrogen permeation rate was reduced to 1/1000 or lower by the DLC coatings. The DLC coatings with high hydrogen content had high hydrogen barrier function. For hydrogen diffusion in coatings, the movement of atoms through hydrogen trap sites such as pores in coatings, and crystal defects such as dislocations, is important. The DLC coatings are amorphous, and there are both sp3 and sp2 bonds, and excess hydrogen could be found in the interstitial space and the hydrogen trap sites. In the DLC coatings with high hydrogen content, these hydrogen trap sites are likely already filled with hydrogen atoms, and the movement of new hydrogen atoms could be limited.

Keywords: hydrogen permeation, stainless steels, diamond-like carbon, hydrogen trap sites

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Authors: Serafino Di Rosario

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ReS is a sustainable hand-built temporary acoustic shell, developed since 2011 and built during the architectural workshop at Villa Pennisi in Musica in Acireale, Sicily, each year since 2012. The design concept aims to provide a portable structure by reducing the on-site construction problems and the skills required by the builders together with maximizing the acoustic performance for the audience and the musicians. The shell is built using only wood, recycled for the most part, and can be built and dismantled by non-specialized workers in just three days. This paper describes the research process, which spans over four years and presents the final results in form of acoustic simulations performed by acoustic modeling software and real world measurements. ReS is developed by the ReS team who has been presented with the Peter Lord Award in 2015 by the Institute of Acoustics in the UK.

Keywords: acoustic shell, outdoor natural amplification, computational design, room acoustics

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Authors: Victor I. Ilgisonis, Ludmila V. Konovaltseva, Vladimir P. Lakhin, Ekaterina A. Sorokina

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The analytical solutions for geodesic acoustic eigenmodes in tokamak plasmas with circular concentric magnetic surfaces are found. In the frame of ideal magnetohydrodynamics the dispersion relation taking into account the toroidal coupling between electrostatic perturbations and electromagnetic perturbations with poloidal mode number |m| = 2 is derived. In the absence of such a coupling the dispersion relation gives the standard continuous spectrum of geodesic acoustic modes. The analysis of the existence of global eigenmodes for plasma equilibria with both off-axis and on-axis maximum of the local geodesic acoustic frequency is performed.

Keywords: tokamak, MHD, geodesic acoustic mode, eigenmode

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Authors: Terrance Charles, Zhiyin Yang, Yiling Lu

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Heavy trucks are aerodynamically inefficient due to their un-streamlined body shapes, leading to more than of 60% engine power being required to overcome the aerodynamics drag at 60 m/hr. There are many aerodynamics drag reduction devices developed and this paper presents a study on a drag reduction device called Cross Vortex Trap Device (CVTD) deployed in the gap between the tractor and the trailer of a simplified tractor-trailer model. Numerical simulations have been carried out at Reynolds number 0.51×10⁶ based on inlet flow velocity and height of the trailer using the Reynolds-Averaged Navier-Stokes (RANS) approach. Three different configurations of CVTD have been studied, ranging from single to three slabs, equally spaced on the front face of the trailer. Flow field around three different configurations of trap device have been analysed and presented. The results show that a maximum of 12.25% drag reduction can be achieved when a triple vortex trap device is used. Detailed flow field analysis along with pressure contours are presented to elucidate the drag reduction mechanisms of CVTD and why the triple vortex trap configuration produces the maximum drag reduction among the three configurations tested.

Keywords: aerodynamic drag, cross vortex trap device, truck, Reynolds-Averaged Navier-Stokes, RANS

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Authors: Xiang Wang

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In order to validate the efficiency of recognizing the damage initiation and development of a concrete beam using acoustic emission technology, a concrete beam is built and tested in the laboratory. The acoustic emission signals are analyzed based on both parameter and wave information, which is also compared with the beam deflection measured by displacement sensors. The results indicate that using acoustic emission technology can detect damage initiation and development effectively, especially in the early stage of the damage development, which can not be detected by the common monitoring technology. Furthermore, the positioning of the damage based on the acoustic emission signals can be proved to be reasonable. This job can be an important attempt for the future long-time monitoring of the real concrete structure.

Keywords: acoustic emission technology, concrete beam, parameter analysis, wave analysis, positioning

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Authors: Ahmed M. Rashed

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Culicoides midges are known to be vectors of disease to both man and animals. For providing information necessary for control methods to be applied to the best advantage, a New jersey light-trap was used. Twenty species were identified during this study and eight species were recorded from Chantilly for the first time, these include C.grisescens, C.nubeculosus, C.cubitalis, C.achrayi, C.circumscriptus, C.stigma, C.reconditus, and C.parroti. The environmental factors, wind speed and temperature were found to have a marked effect on the activity of Culicoides midges. The temperature was found to be positively correlated and the wind speed negatively correlated with the light-trap catch. However, humidioty could not be shown to have any effect on the catch.

Keywords: culicoides, meteorological factors, wind speed, disease

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Authors: Andreas Johansson

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Conceptual understanding needs to be grounded on observation of physical phenomena, experiences or metaphors. Observation of physical phenomena using demonstration experiments has a long tradition within physics education and students need to develop mental models to relate the observations to concepts from scientific theories. This study investigates how live and video experiments involving an acoustic trap to visualize particle-field interaction, field properties and particle properties can help develop students' mental models and how they can be used differently to realize their potential as teaching tools. Initially, they were treated as analogs and the lesson designs were kept identical. With a design-based approach, the experimental and video designs, as well as best practices for a respective teaching tool, were then developed in iterations. Variation theory was used as a theoretical framework to analyze the planned respective realized pattern of variation and invariance in order to explain learning outcomes as measured by a pre-posttest consisting of conceptual multiple-choice questions inspired by the Force Concept Inventory and the Force and Motion Conceptual Evaluation. Interviews with students and teachers were used to inform the design of experiments and videos in each iteration. The lesson designs and the live and video experiments has been developed to help teachers improve student learning and make school physics more interesting by involving experimental setups that usually are out of reach and to bridge the gap between what happens in classrooms and in science research. As students’ conceptual knowledge also rises their interest in physics the aim is to increase their chances of pursuing careers within science, technology, engineering or mathematics.

Keywords: acoustic trap, design-based research, experiments, variation theory

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Authors: Bo Hu, Shibo Wang, Haoyang Zhang, Jie Shi

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With the development of sonar detection technology, the acoustic stealth technology of underwater vehicles is facing severe challenges. The underwater acoustic coating is developing towards the direction of low-frequency absorption capability and broad absorption frequency bandwidth. In this paper, an acoustic model of underwater acoustic coating of composite material embedded with periodical steel structure is presented. The model has multiple high absorption peaks in the frequency range of 1kHz-8kHz, where achieves high sound absorption and broad bandwidth performance. It is found that the frequencies of the absorption peaks are related to the classic half-wavelength transmission principle. The sound absorption performance of the acoustic model is investigated by the finite element method using COMSOL software. The sound absorption mechanism of the proposed model is explained by the distributions of the displacement vector field. The influence of geometric parameters of periodical steel structure, including thickness and distance, on the sound absorption ability of the proposed model are further discussed. The acoustic model proposed in this study provides an idea for the design of underwater low-frequency broadband acoustic coating, and the results shows the possibility and feasibility for practical underwater application.

Keywords: acoustic coating, composite material, broad frequency bandwidth, sound absorption performance

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Authors: Natalia Ivanova, Konstantin Adamov

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The importance of acoustics in music classes made us analyse three music rooms in a Bulgarian school. The same music piece was performed in every one of the classrooms. The recording was played to 2 groups of students. A survey was then taken among those students in order to determine their personal preferences and impressions of the acoustic. The results show differences in the preferences of older students compared to younger ones. Results of the survey show a correlation between older students’ preferences and the standard requirements. However, we discover that younger students’ classrooms should be further analysed and adapted to their needs and preferences.

Keywords: acousic, building acoustic, sound quality, scool acoustic

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Authors: Arshad Alfoqaha, Seth Bard, Dustin Demetriou

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A new multi-physics acoustic modeling approach using ANSYS Mechanical FEA and FLUENT CFD methods is developed for modeling servers mounted to racks, such as IBM Z and IBM Power Systems, in data centers. This new approach allows users to determine the thermal and acoustic conditions that people are exposed to within the data center. The sound pressure level (SPL) exposure for a human working inside a hot aisle containment system inside the data center is studied. The SPL is analyzed at the noise source, at the human body, on the rack walls, on the containment walls, and on the ceiling and flooring plenum walls. In the acoustic CFD simulation, it is assumed that a four-inch diameter sphere with monopole acoustic radiation, placed in the middle of each rack, provides a single-source representation of all noise sources within the rack. Ffowcs Williams & Hawkings (FWH) acoustic model is employed. The target frequency is 1000 Hz, and the total simulation time for the transient analysis is 1.4 seconds, with a very small time step of 3e-5 seconds and 10 iterations to ensure convergence and accuracy. A User Defined Function (UDF) is developed to accurately simulate the acoustic noise source, and a Dynamic Mesh is applied to ensure acoustic wave propagation. Initial validation of the acoustic CFD simulation using a closed-form solution for the spherical propagation of an acoustic point source is performed.

Keywords: data centers, FLUENT, acoustics, sound pressure level, SPL, hot aisle containment, IBM

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Authors: Vinita Choudhary

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The solidly mounted resonator (SMR) is a bulk acoustic wave-based device consisting of a piezoelectric layer sandwiched between two electrodes upon Bragg reflectors, which then are attached to a substrate. To transform the effective acoustic impedance of the substrate to a near zero value, the Bragg reflectors are composed of alternating high and low acoustic impedance layers of quarter-wavelength thickness. In this work presents the design and investigation of acoustic Bragg reflectors (ABRs) for solidly mounted bulk acoustic wave resonators through analysis and simulation. This performance of the resonator is analyzed using 1D Mason modeling. The performance parameters are the effect of Bragg pairs number on transmissivity, reflectivity, insertion loss, the electromechanical and quality factor of the 5GHz operating resonator.

Keywords: bragg reflectors, SMR, insertion loss, quality factor

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Authors: Faisal AlShammari, Abdulmajid Addali

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Monitoring the conditions of rotating machinery as bearing is important in order to improve its stability of works. Acoustic emission (AE) and vibration analysis are some of the most accomplished techniques used for this purpose. Acoustic emission has the ability to detect the initial phase of component degradation. Moreover, it has been observed that the success of vibration analysis does not take place below 100 rpm rotational speed. This because the energy generated below 100 rpm rotational speed is not detectable using conventional vibration. From this pint, this paper has presented a focused review of using acoustic emission techniques for monitoring bearings condition.

Keywords: condition monitoring, stress wave analysis, low-speed bearings, bearing defect diagnosis

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Authors: Ivanova B. Natalia, Djambova Т. Svetlana, Hristev S. Ivailo

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The acoustic properties of recycled felt panels have been investigated using various methods. Experimentally, the sound insulation of the panels has been evaluated for frequencies in the range of 600 Hz to 4000 Hz, utilizing a small-sized acoustic chamber. Additionally, the sound absorption coefficient for the frequency range of 63 Hz to 4000 Hz was measured according to the EN ISO 354 standard in a laboratory reverberation room. This research was deemed necessary after conducting reverberation time measurements of a university classroom following the EN ISO 3382-2 standard. The measurements indicated values of 2.86 s at 500 Hz, 3.23 s at 1000 Hz, and 2.53 s at 2000 Hz, which significantly exceeded the requirements set by the national regulatory framework (0.6s) for such premises. For this reason, recycled felt panels have been investigated in the laboratory, showing very good acoustic properties at high frequencies. To enhance performance in the low frequencies, the influence of the distance of the panel spacing was examined. Furthermore, the sound insulation of the panels was studied to expand the possibilities of their application, both for the acoustic treatment of educational and multifunctional halls and for sound insulation purposes (e.g., a suspended ceiling with an air gap passing from room to room). As a conclusion, a theoretical acoustic design of the classroom has been carried out with suggestions for improvements to achieve the necessary acoustic and aesthetic parameters for such rooms.

Keywords: acoustic panels, recycled felt, sound absorption, sound insulation, classroom acoustics

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Authors: Mohammad Ali Al-Deeb, Hamda Ateeq Al Dhaheri

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Insects cause major damage to crops and fruit trees worldwide. In the United Arab Emirates, the date palm tree is the most economically important tree which is used for date production as well as an ornamental tree. In 2002, the number of date palm trees in UAE was 40,700,000 and it is increasing over time. The longhorn stem borer (Jebusaea hammerschmidtii) and the lesser date month (Batrachedra amydraula) are important insect pests causing damage to date palm trees in UAE. Population dynamics of the Jebusaea hammerschmidtii and Batrachedra amydraula were studied by using light and pheromons traps, respectively in Al-Ain, UAE. The first trap catch of B. amydraula adults occurred on 19 April and the insect population peaked up on 26 April 2014. The first trap catch of J. hammerschmidtii occurred in April 2014. The numbers increased over time and the population peak occurred in June. The trapping was also done in 2015. The changes in insect numbers in relation to weather parameters are discussed. Also, the importance of the results on the management of these two pests is highlighted.

Keywords: date palm, integrated pest management, UAE, light trap, pheromone trap

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Authors: Dibyendu Roy, V. Ramu Reddy, Parijat Deshpande, Ranjan Dasgupta

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Imaging of underwater objects is primarily conducted by acoustic imagery due to the severe attenuation of electro-magnetic waves in water. Acoustic imagery underwater has varied range of significant applications such as side-scan sonar, mine hunting sonar. It also finds utility in other domains such as imaging of body tissues via ultrasonography and non-destructive testing of objects. In this paper, we explore the feasibility of using active acoustic imagery in air and simulate phased array beamforming techniques available in literature for various array designs to achieve a suitable acoustic sensor array design for a portable mobile robot which can be applied to detect the presence/absence of anomalous objects in a room. The multi-path reflection effects especially in enclosed rooms and environmental noise factors are currently not simulated and will be dealt with during the experimental phase. The related hardware is designed with the same feasibility criterion that the developed system needs to be deployed on a portable mobile robot. There is a trade of between image resolution and range with the array size, number of elements and the imaging frequency and has to be iteratively simulated to achieve the desired acoustic sensor array design. The designed acoustic imaging array system is to be mounted on a portable mobile robot and targeted for use in surveillance missions for intruder alerts and imaging objects during dark and smoky scenarios where conventional optic based systems do not function well.

Keywords: acoustic sensor array, acoustic imagery, anomaly detection, phased array beamforming

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Authors: Fangying Wang, Zhang Sanming, Ni Qian

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In recent years, more and more personalized sound absorbing materials have entered the Chinese room acoustical decoration market. The acoustic performance of three kinds of personalized sound-absorbing materials: Flame-retardant Flax Fiber Sound-absorbing Cotton, Eco-Friendly Sand Acoustic Panel and Transparent Micro-perforated Panel (Film) are tested by Reverberation Room Method. The sound absorption characteristic curves show that their performance match for or even exceed the traditional sound absorbing material. Through the application in the actual projects, these personalized sound-absorbing materials also proved their sound absorption ability and unique decorative effect.

Keywords: acoustic performance, application prospect personalized sound-absorbing materials

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Authors: Saad Bougrine, Salma Ouchraa, Belaid Ahiod, Abdelhakim Ameur El Imrani

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Ant colony optimization is an ant algorithm framework that took inspiration from foraging behaviour of ant colonies. Indeed, ACO algorithms use a chemical communication, represented by pheromone trails, to build good solutions. However, ants involve different communication channels to interact. Thus, this paper introduces the acoustic communication between ants while they are foraging. This process allows fine and local exploration of search space and permits optimal solution to be improved.

Keywords: acoustic communication, ant colony optimization, local search, traveling salesman problem

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Authors: Nirav J. Patel, Kalpesh K. Dudani

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Partial discharge (PD) is the dissipation of energy caused by localized breakdown of insulation. Power transformers are one of the most important components in the electrical energy network. Insulation degradation of transformer is frequently linked to PD. This is why PD detection is used in power system to monitor the health of high voltage transformer. If such problem are not detected and repaired, the strength and frequency of PD may increase and eventually lead to the catastrophic failure of the transformer. This can further cause external equipment damage, fires and loss of revenue due to an unscheduled outage. Hence, reliable online PD detection is a critical need for power companies to improve personnel safety and decrease the probability of loss of service. The PD phenomenon is manifested in a variety of physically observable signals including Ultra High Frequency (UHF) radiation and Acoustic Disturbances, Electrical pulses. Acoustic method is based on sensing the radiated acoustic emission from discharge sites in the insulation. Propagated wave from the PD fault site are captured sensor are consequently pre-amplified, filtered, recorded and analyze.

Keywords: acoustic, partial discharge, perfectly matched layer, sensor

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Authors: Ahmadali Shirazytabar, Hamidreza Namazi

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The inherent irreversibility of thermo-acoustics primarily in the stack region causes poor efficiency of thermo-acoustic engines which is the major weakness of these devices. In view of the above, this study examines entropy generation in the stack of a thermo-acoustic system. For this purpose two parallel plates representative of the stack is considered. A general equation for entropy generation is derived based on the Second Law of thermodynamics. Assumptions such as Rott’s linear thermo-acoustic approximation, boundary layer type flow, etc. are made to simplify the governing continuity, momentum and energy equations to achieve analytical solutions for velocity and temperature. The entropy generation equation is also simplified based on the same assumptions and then is converted to dimensionless form by using characteristic entropy generation. A time averaged entropy generation rate followed by a global entropy generation rate are calculated and graphically represented for further analysis and inspecting the effect of different parameters on the entropy generation.

Keywords: thermo-acoustics, entropy, second law of thermodynamics, Rott’s linear thermo-acoustic approximation

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Authors: Rahmat Ali, Beenish Khan, Aftabullah, Abid A. Shah

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This research is an attempt to investigate the wide range of events using acoustic emission (AE) sensors of the concrete cubes subjected to different stress condition loading and unloading of concrete cubes. A total of 27 specimens were prepared and tested including 18 cubic (6”x6”x6”) and nine cylindrical (4”x8”) specimens were molded from three batches of concrete using w/c of 0.40, 0.50, and 0.60. The compressive strength of concrete was determined from concrete cylinder specimens. The deterioration of concrete was evaluated using the occurrence of felicity and Kaiser effects at each stress condition. It was found that acoustic emission hits usually exceeded when damage increases. Additionally, the correlation between AE techniques and the load applied were determined by plotting the normalized values. The influence of w/c on sensitivity of the AE technique in detecting concrete damages was also investigated.

Keywords: acoustic emission, concrete, felicity ratio, sensors

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Authors: Z. Hormozi Moghaddam, M. Mokhtari-Dizaji, M. Movahedin, M. E. Ravari

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Mechanical index (MI) is used for quantifying acoustic cavitation and the relationship between acoustic pressure and the frequency. In this study, modeling of the MI was applied to provide treatment protocol and to understand the effective physical processes on reproducibility of stem cells. The acoustic pressure and MI equations are modeled and solved to estimate optimal MI for 28, 40, 150 kHz and 1 MHz frequencies. Radial and axial acoustic pressure distribution was extracted. To validate the results of the modeling, the acoustic pressure in the water and near field depth was measured by a piston hydrophone. Results of modeling and experiments show that the model is consistent well to experimental results with 0.91 and 0.90 correlation of coefficient (p<0.05) for 1 MHz and 40 kHz. Low intensity ultrasound with 0.40 MI is more effective on the proliferation rate of the spermatogonial stem cells during the seven days of culture, in contrast, high MI has a harmful effect on the spermatogonial stem cells. This model provides proper treatment planning in vitro and in vivo by estimating the cavitation phenomenon.

Keywords: ultrasound, mechanical index, modeling, stem cell

Procedia PDF Downloads 334