Search results for: ultrasonic vibration hot embossing

Authors: Takuya Sumi, Syoko Nukaya, Takashi Kaburagi, Hiroshi Tanaka, Kajiro Watanabe, Yosuke Kurihara

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We propose an unconstrained measurement system for scratching motion based on mathematical model of unconstrained bed sensing method which could measure the bed vibrations due to the motion of the person on the bed. In this paper, we construct mathematical model of the unconstrained bed monitoring system, and we apply the unconstrained bed sensing method to the system for detecting scratching motion. The proposed sensors are placed under the three bed feet. When the person is lying on the bed, the output signals from the sensors are proportional to the magnitude of the vibration due to the scratching motion. Hence, we could detect the subject’s scratching motion from the output signals from ceramic sensors. We evaluated two scratching motions using the proposed system in the validity experiment as follows: First experiment is the subject’s scratching the right side cheek with his right hand, and; second experiment is the subject’s scratching the shin with another foot. As the results of the experiment, we recognized the scratching signals that enable the determination when the scratching occurred. Furthermore, the difference among the amplitudes of the output signals enabled us to estimate where the subject scratched.

Keywords: unconstrained bed sensing method, scratching, body movement, itchy, piezoceramics

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Authors: Mohammed Al-Bahrani, Alistair Cree, Zoltan J. Gombos

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Carbon nanotubes are currently considered to be one of the strongest and stiffest engineering materials available, possessing a calculated tensile strength of σTS ≈ 200GPa and Young’s moduli up to E = 1.4 TPa. In the context of manufactured engineering composites, epoxy resin is the most commonly used matrix material for many aerospace and oil field, and other, industrial applications. This paper reports the initial findings of a study which considered the effects that small additions of nickel coated multi-wall carbon nanotubes (Ni-MWCNTs) would have on the mechanical properties of an epoxy resin matrix material. To successfully incorporate these particles into the matrix materials, with good dispersive properties, standard mixing techniques using an ultrasonic bath were used during the manufacture of appropriate specimens for testing. The tensile and flexural strength properties of these specimens, as well as the microstructure, were then evaluated and studied. Scanning Electronics Microscope (SEM) was used to visualise the degree of dispersion of the Ni-MWCNT’s in matrix. The results obtained indicated that the mechanical properties of epoxy resin can be improved significantly by the addition of the Ni-MWCNT’s. Further, the addition of Ni-MWCNT’s increased the tensile strength by approximately 19% and the tensile modulus by 28%. The flexural strength increased by 20.7% and flexural modulus by 22.6% compared to unmodified epoxy resin. It is suggested that these improvements, seen with the Ni-MWCNT’s particles, were due to an increase in the degree of interfacial bonding between Ni-MWCNT and epoxy, so leading to the improved mechanical properties of the nanocomposite observed. Theoretical modelling, using ANSYS finite element analysis, also showed good correlation with the experimental results obtained.

Keywords: carbon nanotubes, nanocomposite, epoxy resin, ansys

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Authors: Shams Ul Khaliq, Mushtaq Zeb, Fawad Bilal, Faizan Akbar, Syed Aamir Abbas

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Self Compacting Concrete as the name implies--is the concrete requiring a very little or no vibration to fill the form homogeneously. Self Compacting Concrete (SCC) is defined by two primary properties: Ability to flow or deform under its own weight (with or without obstructions) and the ability to remain homogeneous while doing so. Flow ability is achieved by utilizing high range water reducing admixtures and segregation resistance is ensured by introducing a chemical viscosity modifying admixture (VMA) or increasing the amount of fines in the concrete. The study explores the use waste marble dust (WMD) to increase the amount of fines and hence achieve self-compatibility in an economical way, suitable for Pakistani construction industry. The study focuses on comparison of fresh properties of SCC containing varying amounts of waste marble dust (WMD) with that containing commercially available viscosity modifying admixture. The comparison is done at different dosages of super plasticizer keeping cement, water, coarse aggregate, and fine aggregate contents constant.

Keywords: self compacting concrete, waste marble dust (WMD), flow ability, segregation resistance

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Authors: Rama Debbarma

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The present study deals with the performance of Linear base isolation system to mitigate seismic response of structures characterized by random system parameters. This involves optimization of the tuning ratio and damping properties of the base isolation system considering uncertain system parameters. However, the efficiency of base isolator may reduce if it is not tuned to the vibrating mode it is designed to suppress due to unavoidable presence of system parameters uncertainty. With the aid of matrix perturbation theory and first order Taylor series expansion, the total probability concept is used to evaluate the unconditional response of the primary structures considering random system parameters. For this, the conditional second order information of the response quantities are obtained in random vibration framework using state space formulation. Subsequently, the maximum unconditional root mean square displacement of the primary structures is used as the objective function to obtain optimum damping parameters Numerical study is performed to elucidate the effect of parameters uncertainties on the optimization of parameters of linear base isolator and system performance.

Keywords: linear base isolator, earthquake, optimization, uncertain parameters

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Authors: Rahul Kumar, Pavuluri Srinivasa Rao

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This study investigates the effect of ultrasound-assisted high pressure (HP) treatment on the soaking characteristic of soybeans and extracted soy milk quality. The soybean (variety) was subjected to sonication (US) at ambient temperature for 15 and 30 min followed by HP treatment in the range of 200-400 MPa for dwell times 5-10 min. The bean samples were also compared with HPP samples (200-400 MPa; 5-10 mins), overnight soaked samples(12-15 h) and thermal treated samples (100°C/30 min) followed by overnight soaking for 12-15 h soaking. Rapid soaking within 40 min was achieved by the combined US-HPP treatment, and it reduced the soaking time by about 25 times in comparison to overnight soaking or thermal treatment followed by soaking. Reducing the soaking time of soybeans is expected to suppress the development of undesirable beany flavor of soy milk developed during normal soaking milk extraction. The optimum moisture uptake by the sonicated-pressure treated soybeans was 60-62% (w.b) similar to that obtained after overnight soaking for 12-15 h or thermal treatment followed by overnight soaking. pH of soy milk was not much affected by the different US-HPP treatments and overnight soaking which centered around the range of 6.6-6.7 much like the normal cow milk. For milk extracted from thermally treated soy samples, pH reduced to 6.2. Total soluble solids were found to be maximum for the normal overnight soaked soy samples, and it was in the range of 10.3-10.6. For the HPP treated soy milk, the TSS reduced to 7.4 while sonication further reduced it to 6.2. TSS was found to be getting reduced with increasing time of ultrasonication. Further reduction in TSS to 2.3 was observed in soy milk produced from thermally treated samples following overnight soaking. Our results conclude that thermally treated beans' milk is less stable and more acidic, soaking is very rapid compared to overnight soaking hence milk productivity can be enhanced with less development of undesirable beany flavor.

Keywords: beany flavor, high pressure processing, high pressure, soybean, soaking, milk, ultrasound, wet basis

Procedia PDF Downloads 231

Authors: A. Bogdanovic, M. Vitanova, J. Bojadjieva, Z. Rakicevic, V. Sesov, K. Edip, N. Naumovski, F. Manojlovski, A.Popovska, A. Shoklarovski, T. Kitanovski, D. Ivanovski, I. Markovski, D. Filipovski

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The conditions of existing structures change in the course of time and can hardly be characterized particularly if a bridge has long been in function and there is no design documentation related to it. To define the real conditions of a structure, detailed static and dynamic analysis of the structure has to be carried out and its modal parameters have to be defined accurately. Modal analysis enables a quite accurate identification of the natural frequencies and mode shapes. Presented in this paper are the results from the performed detailed analyses of a steel truss bridge that has been in use for more than 7 decades by the military services of R.N. Macedonia and for which there is no documentation at all. Static and dynamic investigations and ambient vibration measurements were performed. The acquired data were used to identify the mode shapes that were used for comparison with the numerical model. Dynamic tests were performed to define the bridge behaviour and the damping index. Finally, based on all the conducted detailed analyses and investigations, conclusions on the conditions of the bridge structure were drawn.

Keywords: ambient vibrations, dynamic identification, in-situ measurement, steel truss bridge

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Authors: Krzysztof Skiba, Zbigniew Czyz, Ksenia Siadkowska, Piotr Borowiec

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The article presents selected concepts of technologies that use intelligent materials in aircraft in order to improve their performance. Most of the research focuses on solutions that improve the performance of fixed wing aircraft due to related to their previously dominant market share. Recently, the development of the rotorcraft has been intensive, so there are not only helicopters but also gyroplanes and unmanned aerial vehicles using rotors and vertical take-off and landing. There are many different technologies to change a shape of the aircraft or its elements. Piezoelectric, deformable actuator systems can be applied in the system of an active control of vibration dampening in the aircraft tail structure. Wires made of shape memory alloys (SMA) could be used instead of hydraulic cylinders in the rear part of the aircraft flap. The aircraft made of intelligent materials (piezoelectrics and SMA) is one of the NASA projects which provide the possibility of changing a wing shape coefficient by 200%, a wing surface by 50%, and wing deflections by 20 degrees. Active surfaces made of shape memory alloys could be used to control swirls in the flowing stream. An intelligent control system for helicopter blades is a method for the active adaptation of blades to flight conditions and the reduction of vibrations caused by the rotor. Shape memory alloys are capable of recovering their pre-programmed shapes. They are divided into three groups: nickel-titanium-based, copper-based, and ferromagnetic. Due to the strongest shape memory effect and the best vibration damping ability, a Ni-Ti alloy is the most commercially important. The subject of this work was to prepare a conceptual design of a rotor blade with SMA actuators. The scope of work included 3D design of the supporting rotor blade, 3D design of beams enabling to change the geometry by changing the angle of rotation and FEM (Finite Element Method) analysis. The FEM analysis was performed using NX 12 software in the Pre/Post module, which includes extended finite element modeling tools and visualizations of the obtained results. Calculations are presented for two versions of the blade girders. For FEM analysis, three types of materials were used for comparison purposes (ABS, aluminium alloy 7057, steel C45). The analysis of internal stresses and extreme displacements of crossbars edges was carried out. The internal stresses in all materials were close to the yield point in the solution of girder no. 1. For girder no. 2 solution, the value of stresses decreased by about 45%. As a result of the displacement analysis, it was found that the best solution was the ABS girder no. 1. The displacement of about 0.5 mm was obtained, which resulted in turning the crossbars (upper and lower) by an angle equal to 3.59 degrees. This is the largest deviation of all the tests. The smallest deviation was obtained for beam no. 2 made of steel. The displacement value of the second girder solution was approximately 30% lower than the first solution. Acknowledgement: This work has been financed by the Polish National Centre for Research and Development under the LIDER program, Grant Agreement No. LIDER/45/0177/L-9/17/NCBR/2018.

Keywords: aircraft, helicopters, shape memory alloy, SMA, smart material, unmanned aerial vehicle, UAV

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Authors: M. Masłowski, M. Zaborski

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Magnetorheological elastomer composites based on micro- and nano-sized magnetite, gamma iron oxide and carbonyl iron powder in ethylene-octene rubber are reported and studied. The method of preparation process influenced the specific properties of MREs (isotropy/anisotropy). The use of extrusion method instead of traditional preparation processes (two-roll mill, mixer) of composites is presented. Micro and nan-sized magnetites as well as gamma iron oxide and carbonyl iron powder were found to be an active fillers improving the mechanical properties of elastomers. They also changed magnetic properties of composites. Application of extrusion process also influenced the mechanical properties of composites and the dispersion of magnetic fillers. Dynamic-mechanical analysis (DMA) indicates the presence of strongly developed secondary structure in vulcanizates. Scanning electron microscopy images (SEM) show that the dispersion improvement had significant effect on the composites properties. Studies investigated by vibration sample magnetometer (VSM) proved that all composites exhibit good magnetic properties.

Keywords: extrusion, magnetic fillers, magnetorheological elastomers, mechanical properties

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Authors: Federico Valenzuela-Beltran, Sonia E. Ruiz, Alfredo Reyes-Salazar, Juan Bojorquez

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A reliability-based methodology which uses structural demand hazard curves to consider the increment of the ductility demands of structures with tilting is proposed. The approach considers the effect of two orthogonal components of the ground motions as well as the influence of soil-structure interaction. The approach involves the calculation of ductility demand hazard curves for symmetric systems and, alternatively, for systems with different degrees of asymmetry. To get this objective, demand hazard curves corresponding to different global ductility demands of the systems are calculated. Next, Uniform Exceedance Rate Spectra (UERS) are developed for a specific mean annual rate of exceedance value. Ratios between UERS corresponding to asymmetric and to symmetric systems located in soft soil of the valley of Mexico are obtained. Results indicate that the ductility demands corresponding to tilted structures may be several times higher than those corresponding to symmetric structures, depending on several factors such as tilting angle and vibration period of structure and soil.

Keywords: asymmetric yielding, seismic performance, structural reliability, tilted structures

Procedia PDF Downloads 487

Authors: Sung-Hyeon Park, Jin-Wook Jang, Hak-Sung Kim

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In recent years, Terahertz (THz) time-domain spectroscopy (TDS) imaging method has been received considerable interest as a promising non-destructive technique for detection of internal defects. In comparison to other non-destructive techniques such as x-ray inspection method, scanning acoustic tomograph (SAT) and microwave inspection method, THz-TDS imaging method has many advantages: First, it can measure the exact thickness and location of defects. Second, it doesn’t require the liquid couplant while it is very crucial to deliver that power of ultrasonic wave in SAT method. Third, it didn’t damage to materials and be harmful to human bodies while x-ray inspection method does. Finally, it exhibits better spatial resolution than microwave inspection method. However, this technology couldn’t be applied to IC package because THz radiation can penetrate through a wide variety of materials including polymers and ceramics except of metals. Therefore, it is difficult to detect the defects in IC package which are composed of not only epoxy and semiconductor materials but also various metals such as copper, aluminum and gold. In this work, we proposed a special method for detecting the void in the IC package using THz-TDS imaging system. The IC package specimens for this study are prepared by Packaging Engineering Team in Samsung Electronics. Our THz-TDS imaging system has a special reflection mode called pitch-catch mode which can change the incidence angle in the reflection mode from 10 o to 70 o while the others have transmission and the normal reflection mode or the reflection mode fixed at certain angle. Therefore, to find the voids in the IC package, we investigated the appropriate angle as changing the incidence angle of THz wave emitter and detector. As the results, the voids in the IC packages were successfully detected using our THz-TDS imaging system.

Keywords: terahertz, non-destructive technique, void, IC package

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Authors: Aravindhan Nepolean, Chidamabaranathan Bibin, Rajesh K., Gopinath S., Ashok Kumar R., Arun Kumar S., Sadasivan N.

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Wind turbine blades are an important parameter for surging renewable energy production. Optimizing blade profiles and developing new materials for wind turbine blades take a lot of time and effort. Even though many standards for wind turbine blades have been developed for large-scale applications, they are not more effective in small-scale applications. We used acrylonitrile-butadiene-styrene to make small-scale wind turbine blades in this study (ABS). We chose the material because it is inexpensive and easy to machine into the desired form. They also have outstanding chemical, stress, and creep resistance. The blade measures 332 mm in length and has a 664 mm rotor diameter. A modal study of blades is carried out, as well as a comparison with current e-glass fiber. They were able to balance the output with less vibration, according to the findings. Q blade software is used to simulate rotating output. The modal analysis testing and prototype validation of wind turbine blades were used for experimental validation.

Keywords: acrylonitrile-butadiene-styrene, e-glass fiber, modal, renewable energy, q-blade

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Authors: H. Masaeli, R. Ziaei, F. Khoshnoudian

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Shock response analysis of the soil–structure systems induced by near–fault pulses is investigated. Vibration transmissibility of the soil–structure systems is evaluated by Shock Response Spectra (SRS). Medium–to–high rise buildings with different aspect ratios located on different soil types as well as different foundations with respect to vertical load bearing safety factors are studied. Two types of mathematical near–fault pulses, i.e. forward directivity and fling step, with different pulse periods as well as pulse amplitudes are selected as incident ground shock. Linear versus nonlinear Soil–Structure Interaction (SSI) condition are considered alternatively and the corresponding results are compared. The results show that nonlinear SSI is likely to amplify the acceleration responses when subjected to long–period incident pulses with normalized period exceeding a threshold. It is also shown that this threshold correlates with soil type, so that increased shear–wave velocity of the underlying soil makes the threshold period decrease.

Keywords: nonlinear soil–structure interaction, shock response spectrum, near–fault ground shock, rocking isolation

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Authors: Raef Cherif, Houssine Bakkali, Wafaa El Khatiri, Yacine Yaddaden

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The analysis of how vibrations are transmitted between components is required in many engineering applications. Transfer path analysis (TPA) has been a valuable engineering tool for solving Noise, Vibration, and Harshness (NVH problems using sub-structuring applications. The most challenging part of a TPA analysis is estimating the equivalent forces at the contact points between the active and the passive side. Component TPA in situ Method calculates these forces by inverting the frequency response functions (FRFs) measured at the passive subsystem, relating the motion at indicator points to forces at the interface. However, matrix inversion could pose problems due to the ill-conditioning of the matrices leading to inaccurate results. This paper establishes a TPA model for an academic system consisting of two plates linked by four springs. A numerical study has been performed to improve the interface forces identification. Several parameters are studied and discussed, such as the singular value rejection and the number and position of indicator points chosen and used in the inversion matrix.

Keywords: transfer path analysis, matrix inverse method, indicator points, SVD decomposition

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Authors: Amit Keshav

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Waste bone, produced in large quantity (8-10 kg./day) from a slaughterhouse, could be a cheap (cost $0.20 per kg) substitute for commercial catalysts. In the present work, catalyst for esterification reaction was prepared from waste bone and characterized by various techniques. Bone was deoiled and then sulfonated. Fourier-transform infrared spectroscopy (FTIR) spectra of prepared catalyst predicted –OH vibration at 3416 and 1630 cm⁻¹, S-O stretching at 1124 cm⁻¹ and intense bands of hydroxypatite in a region between 500 and 700 cm⁻¹. X-ray diffraction (XRD) predicts peaks of hydroxyapatite, CaO, and tricalcium phosphate. Scanning electron microscope (SEM) was employed to reveal the presence of non-uniformity deposited fine particles on the catalyst surface that represents active acidic sites. The prepared catalyst was employed to study its performance on esterification reaction between acrylic acid and ethanol in a molar ratio of 1:1 at a set temperature of 60 °C. Results show an equilibrium conversion of 49% which is matched to the commercial catalysts employed in literature. Thus waste bone could be a good catalyst for acrylic acid removal from waste industrial streams via the process of esterification.Keywords— Heterogeneous catalyst, characterization, esterification, equilibrium conversion

Keywords: heterogeneous catalyst, characterization, esterification, equilibrium conversion

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Authors: Y. Khulief, S. Bashmal, S. Said, D. Al-Otaibi, K. Mansour

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The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross-flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model for square tube arrays was extended and utilized to study the triangular tube patterns. A laboratory test rig with instrumented test section is used to measure the fluidelastic coefficients to be used for tuning the mathematical model. The test section can be made of any bundle pattern. In this study, two test sections were constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized in predicting the onset of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations. The results of the four different tube patterns are viewed in the light of TEMA predictions. The comparison demonstrated that TEMA guidelines are more conservative in all configurations considered

Keywords: fluid-structure interaction, cross-flow, heat exchangers,

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Authors: Kim Byeong-Gon, Lee Pureun-Haneul, Hong Jisu, Jang An-Soo

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Background: Diesel exhaust particles (DEPs) lead to trigger airway hyperresponsiveness (AHR) and airway dysfunction or inflammation in respiratory systems. Whether tight junction protein changes can contribute to development or exacerbations of airway diseases remain to be clarified. Objective: The aim of this study was to observe the effect of DEP on tight junction proteins in one airway both nose and lung in a mouse model. Methods: Mice were treated with saline (Sham) and exposed to 100 μg/m³ DEPs 1 hour a day for 5 days a week for 4 weeks and 8 weeks in a closed-system chamber attached to a ultrasonic nebulizer. Airway hyperresponsiveness (AHR) was measured and bronchoalveolar lavage (BAL) fluid, nasal lavage (NAL) fluid, lung and nasal tissue was collected. The effects of DEP on tight junction proteins were estimated using western blot, immunohistochemical in lung and nasal tissue. Results: Airway hyperresponsiveness and number of inflammatory cells were higher in DEP exposure group than in control group, and were higher in 4 and 8 weeks model than in control group. The expression of tight junction proteins CLND4, -5, and -17 in both lung and nasal tissue were significantly increased in DEP exposure group than in the control group. Conclusion: These results suggesting that CLDN4, -5 and -17 may be involved in the airway both nose and lung, suggesting that air pollutants cause to disruption of epithelial and endothelial cell barriers. Acknowledgment: This research was supported by Korea Ministry of Environment (MOE) as 'The Environmental Health Action Program' (2016001360009) and Soonchunhyang University Research Fund.

Keywords: diesel exhaust particles, air pollutant, tight junction, Claudin, Airway inflammation

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Authors: Y. Yang, Dian Ming Xing, Qiu Hua Du

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Based on the Motorized Momentum Exchange Tether (MMET), with the principle of momentum exchange, the three dimension flexible dynamics of continuous cislunar payloads transferring system (CCPTS) is built by Lagrange method and its numerical solution is solved by Mathematica software. In the derivation precession of potential energy, this paper uses the Tylor expansion method to simplify the Lagrange equation. Furthermore, the tension coming from the centripetal load is considered in the elastic potential energy. The comparison simulation results between the 3D rigid model and 3D flexible model of CCPTS shows that the tether flexibility has important influence on CCPTS’s orbital parameters (such as radius of CCPTS’s COM and the true anomaly) and the tether’s rotational movement, the relative deviation of radius and the true anomaly between the two dynamic models is about 0.00678% and 0.00259%, the relative deviation of the angle of tether-span and local gravity gradient is about 3.55%. Additionally, the external torque has an apparent influence on the tether’s axial vibration.

Keywords: cislunar transfer, dynamics, momentum exchange, tether

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Authors: Rahul Saini, Roshan Lal

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The present paper deals with the free axisymmetric vibrations of bi-directional functionally graded circular plates using Mindlin’s plate theory and physical neutral surface. The temperature-dependent, as well as temperature-independent mechanical properties of the plate material, varies in radial and transverse directions. Also, temperature profile for one- and two-dimensional temperature variations has been obtained from the heat conduction equation. A simple computational formulation for the governing differential equation of motion for such a plate model has been derived using Hamilton's principle for the clamped and simply supported plates at the periphery. Employing the generalized differential quadrature method, the corresponding frequency equations have been obtained and solved numerically to retain their lowest three roots as the natural frequencies for the first three modes. The effect of various other parameters such as temperature profile, functionally graded indices, and boundary conditions on the vibration characteristics has been presented. In order to validate the accuracy and efficiency of the method, the results have been compared with those available in the literature.

Keywords: bi-directionally FG, GDQM, Mindlin’s circular plate, neutral axis, vibrations

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Authors: Serdal Sabanci, Mutlu Çevik, Derya Tezcan, Cansu Çelebi, Filiz Içier

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Ultrasound is defined as sound waves having frequencies higher than 20 kHz, which is greater than the limits of the human hearing range. In recent years, ultrasonic treatment is an emerging technology being used increasingly in the food industry. It is applied as an alternative technique for different purposes such as microbial and enzyme inactivation, extraction, drying, filtration, crystallization, degas, cutting etc. Red beetroot (Beta vulgaris L.) is a root vegetable which is rich in mineral components, folic acid, dietary fiber, anthocyanin pigments. In this study, the application of low frequency high intensity ultrasound to the red beetroot slices and red beetroot juice for different treatment times (0, 5, 10, 15, 20 min) was investigated. Ultrasonicated red beetroot slices were also squeezed immediately. Changes on colour, betanin, pH and titratable acidity properties of red beetroot juices (the ultrasonicated juice (UJ) and the juice from ultrasonicated slices (JUS)) were determined. Although there was no significant difference statistically in the changes of color value of JUS samples due to ultrasound application (p>0.05), the color properties of UJ samples ultrasonicated for low durations were statistically different from raw material (p<0.05). The difference between color values of UJ and raw material disappeared (p>0.05) as the ultrasonication duration increased. The application of ultrasound to red beet root slices adversely affected and decreased the betanin content of JUS samples. On the other hand, the betanin content of UJ samples increased as the ultrasonication duration increased. Ultrasound treatment did not affect pH and titratable acidity of red beetroot juices statistically (p>0.05). The results suggest that ultrasound technology is the simple and economical technique which may successfully be employed for the processing of red beetroot juice with improved color and betanin quality. However, further investigation is still needed to confirm this.

Keywords: red beetroot, ultrasound, color, betanin

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Authors: Humayun R. H. Kabir

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An analytical solution before used for static and free-vibration response has been extended for thermal buckling response on cylindrical panel with anti-symmetric laminations. The partial differential equations that govern kinematic behavior of shells produce five coupled differential equations. The basic displacement and rotational unknowns are similar to first order shear deformation theory---three displacement in spatial space, and two rotations about in-plane axes. No drilling degree of freedom is considered. Boundary conditions are considered as complete hinge in all edges so that the panel respond on thermal inductions. Two sets of double Fourier series are considered in the analytical solution process. The sets are selected that satisfy mixed type of natural boundary conditions. Numerical results are presented for the first 10 eigenvalues, and first 10 mode shapes for Ux, Uy, and Uz components. The numerical results are compared with a finite element based solution.

Keywords: higher order shear deformation, composite, thermal buckling, angle-ply laminations

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Authors: Mei Xutao, Nakano Kimihiko

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In order to enhance the energy harvesting efficiency, this paper presents a novel tri-stable energy harvesting system (TEHS), which is realized by the effect of magnetic force, in rotational motion to scavenge vibration energy. The device is meant to provide the power supply for wireless autonomous systems in low-frequency environment. The nonlinear TEHS is composed of the cantilever beam which is mounted on a rotating hub and partially covered by piezoelectric patch, a tip mass magnet in the end and two fixed magnets. A theoretical investigation using the Lagrangian formulation is derived to describe the motion of the energy harvesting system and the output voltage. Additionally, several numerical simulations were carried out to characterize the system under different external excitations and to validate its performance. The results demonstrated that TEHS owns a wide range of frequency of snap-through and high output voltage compared with the bi-stable energy harvesting system (BEHS). Moreover, some sets of experimental validations will be performed in the future work because the experimental setup is in the configuration now.

Keywords: piezoelectric beam, rotational motion, snap-through, tri-stable energy harvester

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Authors: A. Abbas, X. Tridon, J. Michelon

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In the electronic or in the photovoltaic industries, components are made from wafers which are stacks of thin film layers of a few nanometers to serval micrometers thickness. Early evaluation of the bounding quality between different layers of a wafer is one of the challenges of these industries to avoid dysfunction of their final products. Traditional pump-probe experiments, which have been developed in the 70’s, give a partial solution to this problematic but with a non-negligible drawback. In fact, on one hand, these setups can generate and detect ultra-high ultrasounds frequencies which can be used to evaluate the adhesion quality of wafer layers. But, on the other hand, because of the quiet long acquisition time they need to perform one measurement, these setups remain shut in punctual measurement to evaluate global sample quality. This last point can lead to bad interpretation of the sample quality parameters, especially in the case of inhomogeneous samples. Asynchronous Optical Sampling (ASOPS) systems can perform sample characterization with picosecond acoustics up to 106 times faster than traditional pump-probe setups. This last point allows picosecond ultrasonic to unlock the acoustic imaging field at the nanometric scale to detect inhomogeneities regarding sample mechanical properties. This fact will be illustrated by presenting an image of the measured acoustical reflection coefficients obtained by mapping, with an ASOPS setup, a 255nm thin-film tungsten layer deposited on a silicone substrate. Interpretation of the coefficient reflection in terms of bounding quality adhesion will also be exposed. Origin of zones which exhibit good and bad quality bounding will be discussed.

Keywords: adhesion, picosecond ultrasonics, pump-probe, thin film

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Authors: Ogbuagu Josephat Okechukwu, Okeke Abuchi Princewill, Arinze Rosemary Uche, Tabugbo Ifeyinwa Blessing, Ogbuagu Adaora Stellamaris

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Phthalates or Phthalate esters (PAEs), categorized as an endocrine disruptor and persistent organic pollutants, are known for their environmental contamination and toxicological effects. In this study, the concentration of selected phthalates was determined across the sampling site to investigate their occurrence and the ecological and health risk assessment they pose to the environment. Water and sediment samples were collected following standard procedures. Solid phase and ultrasonic methods were used to extract seven different PAEs, which were analyzed by Gas Chromatography with Mass Detector (GCMS). The analytical average recovery was found to be within the range of s83.4% ± 2.3%. The results showed that PAEs were detected in six out of seven samples with a high percentage of detection rate in water. Di-n-butyl phthalate (DPB) and diisobutyl phthalates (DiBP) showed greater detection rate compared to other PAEs monomers. The concentration of PEs was found to be higher in the sediment samples compared to the water samples due to the fact that sediments serve as a sink for most persistent organic pollutants. The concentrations of PAEs in water samples and sediments ranged from 0.03 ± 0.01 to 0.29 ± 0.002 ppm and 3.99 ± 0.43 to 6.04 ± 1.25 ppm, respectively. Ecological risk assessment using the risk quotient method (RQ) reveals that the estimated environmental risk caused by phthalates lies within the moderate level as RQ ranges from 0.1 to 1.0, whereas the health risk assessment caused by phthalates on estimating the average daily dose reveals that the ingestion of phthalates was found to be high which can cause serious carcinogenic occurrence in the human system with time due to excess accumulation.

Keywords: phthaletes, assessment, marine pollution, endocrine

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Authors: Ravi Chaithanya Mysa, Abouzar Kaboudian, Boo Cheong Khoo, Rajeev Kumar Jaiman

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The phenomenon of vortex-induced vibration has applications in off-shore industry, power transmission, energy extraction, etc. Two cylinders in crossflow whose centers are displaced in transverse direction are considered in the present work. The effects of the gap distance between the cylinders on the vortex shedding are presented. The inline distance between the cylinder centers is kept at zero. Two setups are considered for the study: first, we assume the two cylinders vibrate as a single rigid body mounted on a spring, and in the other case, each cylinder is mounted on a separate spring with no rigid connection to the other cylinder. The study focuses on the effect of transverse gap on the fluid-structure coupled response of two setups mentioned and corresponding flow contours. Incompressible flow is assumed in the Eulerian framework. The cylinder movement is modeled by a single degree of freedom rigid body motion (translational motion) in the Lagrangian framework. The governing equations were numerically solved by standard Petrov-Galerkin second order finite element schemes.

Keywords: cross-flow, vortex-induced vibrations, cylinder, close proximity

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Authors: Pawel Pistelok

Abstract:

The article presents the concept of an electromagnetic circuit of a 3-phase surface-mounted permanent magnet generator designed for a single phase operation. A cross section of electromagnetic circuit and a field-circuit model of generator used for computations are shown. The paper presents comparative analysis of simulation results obtained for two different versions of generator regarding construction of armature winding. In the first version of generator the voltages generated in each of three winding phases have different rms values (different number of turns in each of phases), three winding phases are connected in series and one phase load is connected to the two output terminals of generator. The second version of generator is very similar, i.e. three winding phases are connected in series and one phase load is powered by generator, but in this version the voltages generated in each of winding phases have exactly the same rms values (the same number of turns in each of phases). The time waveforms of voltages, currents and electromagnetic torques in the airgaps of two machine versions for rated power are shown.

Keywords: permanent magnet generator, permanent magnets, synchronous generator, vibration, course of torque, single phase work, unsymmetrical operation point, serial connection of winding phase

Procedia PDF Downloads 666

Authors: M.S. El-Feky, Passant Youssef, Mohamed I. Serag

Abstract:

nowadays, nanotechnology is the main trend of research in different areas due to the new potential of using nanometer materials sized less than 100nm. Nanomaterials are needed in cement composites to act as bridging for Nano and micro-cracks to increase tensile strength, reduce the permeability of gases and water in concrete to solve corrosion problem, react with excess Calcium Hydroxide, produce additional C-S-H, act as filler materials to densify the cement matrix and increase its mechanical properties. The present study focuses on the effectiveness of super-plasticizers and ultrasonic processing on the dispersion of Carbon Nanotube at first in water and then in cement composites in combination with Nano silica to enhance the mechanical properties of cement composites. A qualitative analysis using a compressive strength test is conducted with a view to investigate the influence of different dispersion techniques on the mechanical properties of cement composites containing Carbon Nanotube (CNT) and Nano Silica (NS) particles with different percentages. In addition, micro-structural analysis was carried out to understand the surface morphology and microstructure of cement composites with different dosages of NS addition. The investigational study results showed that the combination of NS with a low amount of CNT had a positive effect on the hydration reaction; on the other hand, the combination of CNT and a high amount of NS had a negative effect on the hydration reaction. The compressive strength can be improved by optimum combination 0.02% CNT and 1% NS with gain in strength by 72% and 35% after 7 and 28 days compared to control samples; these results were with an agreement with the morphology structure of composites using microstructure analysis.

Keywords: nano silica, dispersion, sonication, carbon nano tubes

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Authors: Ganga K. V. Prakhya, V. Karthigeyan

Abstract:

The paper describes the influences of the fluid and structure interaction in concrete structures that support large oil platforms in the North Sea. The dynamic interaction of the fluid both in 2D and 3D are demonstrated through a Computational Fluid Dynamics analysis in the event of explosion following a gas leak inside of the concrete column. The structural response characteristics of the column in water under dynamic conditions are quite complex involving axial, radial and circumferential modes. Fluid structure interaction (FSI) modelling showed that there are some frequencies of the column in water which are not found for a column in air. For example, it was demonstrated that one of the axial breathing modes can never be simulated without the use of FSI models. The occurrence of a shift in magnitude and time of pressure from explosion following gas leak along the height of the shaft not only excited the modes of vibration involving breathing (axial), bending and squashing (radial) modes but also magnified the forces in the column. FSI models revealed that dynamic effects resulted in dynamic amplification of loads. The results are summarized from a detailed study that was carried out by the first author for the Offshore Safety Division of Health & Safety Executive United Kingdom.

Keywords: concrete, explosion, fluid structure interaction, offshore structures

Procedia PDF Downloads 164

Authors: C. Yaddaden, M. Berouaken, L. Talbi, K. Ayouz, M. Ayat, A. Cheriet, F. Boudeffar, A. Manseri, N. Gabouze

Abstract:

Lithium-ion batteries (LIBs) are widely used in various electronic devices due to their high energy density. However, the performance of the anode material in LIBs is crucial for enhancing the battery's overall efficiency. This research focuses on developing a new anode material by modifying silicon nanostructures, specifically porous silicon nanowires (PSiNWs) and porous silicon nanoparticles (NPSiP), with silver nanoparticles (Ag) to improve the performance of LIBs. The aim of this research is to investigate the potential application of PSiNWs/Ag and NPSiP/Ag as anodes in LIBs and evaluate their performance in terms of specific capacity and Coulombic efficiency. The research methodology involves the preparation of PSiNWs and NPSiP using metal-assisted chemical etching and electrochemical etching techniques, respectively. The Ag nanoparticles are introduced onto the nanostructures through electrodissolution of the porous film and ultrasonic treatment. Galvanostatic charge/discharge measurements are conducted between 1 and 0.01 V to evaluate the specific capacity and Coulombic efficiency of both PSiNWs/Ag and NPSiP/Ag electrodes. The specific capacity of the PSiNWs/Ag electrode is approximately 1800 mA h g-1, with a Coulombic efficiency of 98.8% at the first charge/discharge cycle. On the other hand, the NPSiP/Ag electrode exhibits a specific capacity of 2600 mAh g-1. Both electrodes show a slight increase in capacity retention after 80 cycles, attributed to the high porosity and surface area of the nanostructures and the stabilization of the solid electrolyte interphase (SEI). This research highlights the potential of using modified silicon nanostructures as anodes for LIBs, which can pave the way for the development of more efficient lithium-ion batteries.

Keywords: porous silicon nanowires, silicon nanoparticles, lithium-ion batteries, galvanostatic charge/discharge

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Authors: Mojtaba Ghodsi, Hamidreza Ziaifar, Morteza Mohammadzaheri, Payam Soltani

Abstract:

This article presents an analytical model to estimate the harvested power from a Magnetostrictive cantilevered beam with tip excitation. Furthermore, the effects of internal and external damping on harvested power are investigated. The magnetostrictive material in this harvester is Galfenol. In comparison to other popular smart materials like Terfenol-D, Galfenol has higher strength and machinability. In this article, first, a mechanical model of the Euler-Bernoulli beam is employed to calculate the deflection of the harvester. Then, the magneto-mechanical equation of Galfenol is combined with Faraday's law to calculate the generated voltage of the Magnetostrictive cantilevered beam harvester. Finally, the beam model is incorporated in the aforementioned combination. The results show that a 30×8.5×1 mm Galfenol cantilever beam harvester with 80 turn pickup coil can generate up to 3.7 mV and 9 mW. Furthermore, sensitivity analysis made by Response Surface Method (RSM) shows that the harvested power is only sensitive to the internal damping coefficient.

Keywords: internal damping coefficient, external damping coefficient, euler-bernoulli, energy harvester, galfenol, magnetostrictive, response surface method

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Authors: Satya Eswari Jujjavarapu, Swasti Dhagat, Lata Upadhyay, Reecha Sahu

Abstract:

Silver nanoparticles have a broad range of antimicrobial and antifungal properties ranging from soaps, pastes to sterilization and drug delivery systems. These can be synthesized by physical, chemical and biological methods; biological methods being the most popular owing to their non-toxic nature and reduced energy requirements. Microbial surfactants, produced on the microbial cell surface or excreted extracellularly are an alternative to synthetic surfactants for the production of silver nanoparticles. Hence, they are also called as green molecules. Microbial lipopeptide surfactants (biosurfactant) exhibit anti-tumor and anti-microbial properties and can be used as drug delivery agents. In this study, biosurfactant was synthesized by using a strain of acillus subtilis. The biosurfactant thus produced was analysed by emulsification assay, oil spilling test, and haemolytic test. Biosurfactant-mediated silver nanoparticles were synthesised by microwave irradiation of the culture supernatant and further characterized by UV–vis spectroscopy for a range of 400-600 nm. The UV–vis spectra showed a surface plasmon resonance vibration band at 410 nm corresponding to the peak of silver nanoparticles.

Keywords: biosurfactant, Bacillus subtilis, silver nano particle, lipopeptide

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