Search results for: continuous finite elements

Authors: Zorana Sokol Gojnik, Igor Gojnik, Marina Simunic Bursic

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The light is one of the major themes of theology of sacred space. Christian theology, but also architecture in its complexity, is permeated by the symbolism of light from its beginning. The aim of this paper is to deeply analyse the symbolism of light in every single element of contemporary Christian sacred space such as altar, ambo, baptistery, tabernacle, confessionals, stations of the cross, etc. The research will be carried out using the methodology of research of literature and comparatively observation of contemporary examples of sacred architecture. The research will use the insights of analyzed literature and examples of sacred architecture in order to describe the background of the problem as well as to complement the received results with the reliable scientific findings. The paper will highlight the importance of symbolic and theological points of view in contemporary church design using the light as a building part of every single part of sacred architecture as there is an insight that, in contemporary sacred architecture, there is a lack of understanding of symbolic and theological aspect of light while designing new sacred spaces.

Keywords: architecture, liturgy, sacred architecture, theology of space

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Authors: Vivek Verma, Sanjeev Kumar

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This study presents a novel quantum image encryption algorithm, using a 3D chaotic map and controlled qubit-level scrambling operations. The newly proposed 3D-BNM chaotic map effectively reduces the degradation of chaotic dynamics resulting from the finite word length effect. It facilitates the generation of highly unpredictable random sequences and enhances chaotic performance. The system’s efficacy is additionally enhanced by the inclusion of a SHA-256 hash function. Initially, classical plain images are converted into their quantum equivalents using the Novel Enhanced Quantum Representation (NEQR) model. The Generalized Quantum Arnold Transformation (GQAT) is then applied to disrupt the coordinate information of the quantum image. Subsequently, to diffuse the pixel values of the scrambled image, XOR operations are performed using pseudorandom sequences generated by the 3D-BNM chaotic map. Furthermore, to enhance the randomness and reduce the correlation among the pixels in the resulting cipher image, a controlled qubit-level scrambling operation is employed. The encryption process utilizes fundamental quantum gates such as C-NOT and CCNOT. Both theoretical and numerical simulations validate the effectiveness of the proposed algorithm against various statistical and differential attacks. Moreover, the proposed encryption algorithm operates with low computational complexity.

Keywords: 3D Chaotic map, SHA-256, quantum image encryption, Qubit level scrambling, NEQR

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Authors: Muhammad Farooq, Muhammad R. Shahid, M. Shakeel, A. Iftikhar, M. Sagheer, Riaz A. Kainth

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Comparative demography of Coccinella septempunctata Linnaeus (Coleoptera: Coccinellidae) was studied with respect to four host aphid species viz; Rhopalosiphum padi, Rhopalosiphum maidis, Sitobion avenae, and Shizaphis graminum under laboratory conditions using Two-sex Age-stage life table instead of traditional age specific life table which considers only female. Results revealed that developmental period from egg to adult of C. septempunctata were shorter on R. padi (16.49 days) whereas longer on R. maidis (22.83 days). Net reproductive rate varied from 110.01 offspring on R. maidis to 288.78 offspring on R. padi. Mean generation time (T) ranged from 29.02 d on R. padi to 39.788 d on R. maidis. Highest to lowest values of intrinsic rate of increase (rm) were recorded on R. padi, S. graminum, S. avenae, and R. maidis (0.194, 0.143, 0.140 and 0.117 d⁻¹, respectively). Highest finite rate of increase was observed on R. padi (1.214 d⁻¹) followed by S. graminum (1.154 d⁻¹) whereas lowest values were obtained on R. maidis and S. avenae (1.124 and 1.150 d⁻¹, respectively). In this study, the data on the life table of both predator and prey provide useful information in the mass rearing and practical application of a natural agent to biological control systems.

Keywords: C. septempunctata, two-sex age-stage life table, population parameters, aphid species

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Authors: M. D. Fontana, I. Bejaoui Ouni, D. Chapron, H. Aroui

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BaTiO3 (BT) is a well known ferroelectric material which has been thoroughly studied during several decades since it undergoes successive cubic-tetragonal-orthorhombic-rhombohedral phase transitions on cooling. It has several ferroelectric properties that allow it to be a good material for electronic applications such as the design of ferroelectric memories and pyroelectric elements. In the present work, we report the analysis of temperature dependence of Raman frequency and damping of the A1 modes polarized along the FE c axis as well as the optical phonons E corresponding to the ionic motions in the plane normal to c. Measurements were carried out at different temperatures ranging from 298 to 408 K (tetragonal phase) within different scattering configurations. Spectroscopic parameters of BT have determined using a high resolution Raman spectrometer and a fitting program. All the first order frequency modes exhibit a quasi linear decrease as function of the temperature, except for the A1[TO1], E[TO2] and E[TO4] lines which reveal a parabolic dependence illustrating an anharmonic process. The phonon frequency downshifts and damping evolutions are interpreted in terms of normal volume expansion and third- and fourth-order anharmonic potentials.

Keywords: BaTiO3, Raman spectroscopy, frequency, damping, anharmonic potential

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Authors: Saad Ahmed, Sanjeev Khannaa

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Glass fiber reinforced polymers are widely used in structural systems as load-bearing elements at both high and low temperatures. This investigation presents the evaluation of glass fiber reinforced unsaturated polyurethane under harsh conditions of changing temperature and moisture content. This study Explores how these parameters affect the optical properties of the polymer matrix and the composite. Using the hand layup method, the polyurethane resin was modified by E-glass fibers (15 vol. %) to manufacture fiber-reinforced composite. This work includes the preparation of glass-like polyurethane resin sheets and estimates all light transmittance properties at high and very low temperatures and wet conditions. All-optical properties were retested to evaluate the level of improvement or failure. The results found that when comprising reinforced composite fiber to the unreinforced specimens, the reinforced composite shows a fair optical property at high temperatures and good performance at low temperatures.

Keywords: unsaturated polyurethane, extreme temperatures, light transmittance, haze number

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Authors: Ngoc T. B. Hoang

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With a young population showing a greatly entrepreneurial spirit, Vietnam has become a potential land for a growing knowledge-based entrepreneurial ecosystem (KBEE). KBEE is the key to new job formation, and well solution for the crisis of unemployment of higher education graduates and powerful engine for knowledge-based development and building the knowledge based economy in Vietnam. Consequently, Vietnam is attempting to build a healthy KBEE, giving local entrepreneurs more opportunities to develop their businesses. The purpose of the research article is to sketch up a general map to show the current situation of Vietnam's startup ecosystem in the beginning of a startup nation and take into consideration the influence of socio-cultural norms, institutional landscape and socio-economic factors on motivation to develop a KBEE. This paper also proposes a qualitative approach to explore the relationship between these and other elements of Vietnamese entrepreneurial ecosystems. Eventually, viable recommendations are drawn for Vietnamese entrepreneurs and policymakers to improve the quality of the knowledge-based entrepreneurial ecosystem in Vietnam.

Keywords: entrepreneurship, knowledge-based entrepreneurial ecosystem, startup ecosystem, Vietnam

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Authors: K. Tejasri, K. Suvarna Vani, S. Prathyusha, S. Ramya

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Proteins are chained sequences of amino acids which are brought together by the peptide bonds. Many varying formations of the chains are possible due to multiple combinations of amino acids and rotation in numerous positions along the chain. Protein structure prediction is one of the crucial goals worked towards by the members of bioinformatics and theoretical chemistry backgrounds. Among the four different structure levels in proteins, we emphasize mainly the secondary level structure. Generally, the secondary protein basically comprises alpha-helix and beta-sheets. Multi-class classification problem of data with disparity is truly a challenge to overcome and has to be addressed for the beta strands. Imbalanced data distribution constitutes a couple of the classes of data having very limited training samples collated with other classes. The secondary structure data is extracted from the protein primary sequence, and the beta-strands are predicted using suitable machine learning algorithms.

Keywords: proteins, secondary structure elements, beta-sheets, beta-strands, alpha-helices, machine learning algorithms

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Authors: Virendra J. Majarikar, Harikrishnan N. Unni

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This paper sets to demonstrate a modeling of electrokinetic mixing employing electroosmotic stationary and time-dependent microchannel using alternate zeta patches on the lower surface of the micromixer in a lab on chip microfluidic device. Electroosmotic flow is amplified using different 2D and 3D model designs with alternate and geometric zeta potential values such as 25, 50, and 100 mV, respectively, to achieve high concentration mixing in the electrokinetically-driven microfluidic system. The enhancement of electrokinetic mixing is studied using Finite Element Modeling, and simulation workflow is accomplished with defined integral steps. It can be observed that the presence of alternate zeta patches can help inducing microvortex flows inside the channel, which in turn can improve mixing efficiency. Fluid flow and concentration fields are simulated by solving Navier-Stokes equation (implying Helmholtz-Smoluchowski slip velocity boundary condition) and Convection-Diffusion equation. The effect of the magnitude of zeta potential, the number of alternate zeta patches, etc. are analysed thoroughly. 2D simulation reveals that there is a cumulative increase in concentration mixing, whereas 3D simulation differs slightly with low zeta potential as that of the 2D model within the T-shaped micromixer for concentration 1 mol/m³ and 0 mol/m³, respectively. Moreover, 2D model results were compared with those of 3D to indicate the importance of the 3D model in a microfluidic design process.

Keywords: COMSOL Multiphysics®, electrokinetic, electroosmotic, microfluidics, zeta potential

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Authors: Fawwaz Eniola Fajingbesi, Nur Shahida Midia, Elsheikh M. A. Elsheikh, Siti Hajar Yusoff

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Empirical analysis of lightning related phenomena in real time is extremely dangerous due to the relatively high electric discharge involved. Hence, design and optimization of efficient grounding systems depending on real time empirical methods are impeded. Using numerical methods, the dynamics of complex systems could be modeled hence solved as sets of linear and non-linear systems . In this work, the induced current distribution as lightning strike traverses the soil have been numerically modeled in a 2D axial-symmetry and solved using finite element method (FEM) in COMSOL Multiphysics 5.2 AC/DC module. Stratified and non- stratified electrode system were considered in the solved model and soil conductivity (σ) varied between 10 – 58 mS/m. The result discussed therein were the electric field distribution, current distribution and soil ionization phenomena. It can be concluded that the electric field and current distribution is influenced by the injected electric potential and the non-linearity in soil conductivity. The result from numerical calculation also agrees with previously laboratory scale empirical results.

Keywords: current distribution, grounding systems, lightning discharge, numerical model, soil conductivity, soil ionization

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Authors: Dilin Chen, Kang Luo, Jian Wu, Chun Yang, Hongliang Yi

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Electrically driven flows (EDF) systems play an important role in fuel cells, electrochemistry, bioseparation technology, fluid pumping, and microswimmers. The core scientific problem is multifield coupling, the further development of which depends on the exploration of nonlinear instabilities, force competing mechanisms, and energy budgets. In our study, two categories of electrostatic force-dominated phenomena, induced charge electrosmosis (ICEO) and ion conduction pumping are investigated while considering polymer rheological characteristics and heat gradients. With finite volume methods, the thermal modulation strategy of ICEO under the thermal buoyancy force is numerically analyzed, and the electroelastic instability turn associated with polymer addition is extended. The results reveal that the thermal buoyancy forces are sufficient to create typical thermogravitational convection in competition with electroconvective modes. Electroelastic instability tends to be promoted by weak electrical forces, and polymers effectively alter the unstable transition routes. Our letter paves the way for improved mixing and heat transmission in microdevices, as well as insights into the non-Newtonian nature of electrohydrodynamic dynamics.

Keywords: non-Newtonian fluid, electroosmotic flow, electrohydrodynamic, viscoelastic liquids, heat transfer

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Authors: Valeria Piccioni, Matthias Leschok, Ina Cheibas, Illias Hischier, Benjamin Dillenburger, Arno Schlueter, Matthias Kohler, Fabio Gramazio

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The decarbonisation of the building sector requires the development of building components that provide energy efficiency while producing minimal environmental impact. Recent advancements in large-scale 3D printing have shown that it is possible to fabricate components with embedded performances that can be tuned for their specific application. We investigate the potential of polymer 3D printing for the fabrication of translucent facade components. In this study, we explore the effect of geometry on thermal insulation of printed cavity structures following a Hot Box test method. The experimental results are used to calibrate a finite-element simulation model which can support the informed design of 3D printed insulation structures. We show that it is possible to fabricate components providing thermal insulation ranging from 1.7 to 0.95 W/m2K only by changing the internal cavity distribution and size. Moreover, we identify design guidelines that can be used to fabricate components for different climatic conditions and thermal insulation requirements. The research conducted provides the first insights into the thermal behaviour of polymer 3DP facades on a large scale. These can be used as design guidelines for further research toward performant and low-embodied energy 3D printed facade components.

Keywords: 3D printing, thermal performance, polymers, facade components, hot-box method

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Authors: Kaiyi Zhang, Wenlong Li, Haicheng Li, Yifei Luo, Zheng Li, Xiaoshi Wang, Xiaodong Chen

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Plant wearable sensors facilitate the real-time monitoring of plant physiological status. In situ monitoring of the plant chlorophyll content over days could provide valuable information on the photosynthetic capacity, nitrogen content, and general plant health. However, it cannot be achieved by current chlorophyll measuring methods. Here, a miniaturized and plant-wearable chlorophyll meter was developed for rapid, non-destructive, in situ, and long-term chlorophyll monitoring. This reflectance-based chlorophyll sensor with 1.5 mm thickness and 0.2 g weight (1000 times lighter than the commercial chlorophyll meter), includes a light emitting diode (LED) and two symmetric photodetectors (PDs) on a flexible substrate and is patched onto the leaf upper epidermis with a conformal light guiding layer. A chlorophyll content index (CCI) calculated based on this sensor shows a better linear relationship with the leaf chlorophyll content (r² > 0.9) than the traditional chlorophyll meter. This meter can wirelessly communicate with a smartphone to monitor the leaf chlorophyll change under various stresses and indicate the unhealthy status of plants for long-term application of plants under various stresses earlier than chlorophyll meter and naked-eye observation. This wearable chlorophyll sensing patch is promising in smart and precision agriculture.

Keywords: plant wearable sensors, reflectance-based measurements, chlorophyll content monitoring, smart agriculture

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Authors: I. Mentziou, C. Delezos, D. Krikidis, A. Nestoridou, G. Boskou

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Introduction: The systems of production and distribution of meals can have a significant impact on the food intake of hospital patients who are likely to develop malnutrition. In hospitals, the consequences of food borne infections can range from annoying to life-threatening for a patient, since they can lead up to death in vulnerable groups Aim: The aim of the present study was the evaluation of food safety management systems implementation, as well as the general evaluation of the total quality management systems in Greek hospitals. Methods: This is a multifocal study on the implementation and evaluation of the food safety management systems in the Greek hospitals of Attica region. Eleven hospitals from the city of Athens were chosen for this purpose. The sample was derived from the high rank personnel of the nutritional department (dietician, head-chef, food technologist, public health inspector). Tailor made questionnaires on hygiene regulations were used as tools for the interviews. Results: Overall, 30 employees in the field of hospital nutrition participated. Most of the replies implied that almost always the hygiene regulations are implemented. Nevertheless, only 30% stated that there is a Hazard Analysis Critical Control Points HACCP system (HACCP) in the hospital. In a small number of questionnaires there were proposals for changes by the staff. Conclusion: Measurement of the opinion of the personnel about the provided food services within a hospital can further lead to continuous improvement of the hospital nutrition.

Keywords: evaluation, food service, HACCP, hospital, personnel

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Authors: Marisé García Batlle, Juan Manuel Navarrete Tejero

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In aquatic ecosystems, the main indicators of pollution are contaminated sediments, which are the primary repository of radionuclides and chemicals elements in the marine environment. Radioactive Contamination Factor (RCF) has been proposed as a suitable unit to measure the magnitude of radioactive contamination at global scale, caused mainly by more than 2,000 nuclear explosions tests performed during the 1945-65 period. It is obtained as percentage of contaminant radioactivity (¹³⁷Cs) compared to natural radioactivity (⁴⁰K), both expressed in Bq/g of marine sediments conditioned in Marinelli containers and detected in both NaI(Tl) and HPGe detectors. So, in this paper samples of marine sediments were taken up along the occidental Cuban coasts and analyzed by gamma spectrometry for the determination of gamma-emitting radioisotopes with energies between 60 and 2000 keV. The results proved that the proposed method is simple and suitable to evaluated radioactive contamination. Also, the RCF values provide an appropriate indicator to predict which pollution levels in the future will be and if the rate will go down as disintegrates the ¹³⁷Cs present when only 2,4 half-lives have passed away.

Keywords: Cuba, gamma spectrometry, marine sediments, radioactive pollution

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Authors: George N. Zaimes, Valasia Iakovoglou, Paschalis Koutalakis, Konstantinos Ioannou, Ioannis Kosmadakis, Panagiotis Tsardaklis, Theodoros Laopoulos

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The advancements in technology allow the development of a new system that can continuously measure surface soil erosion. Continuous soil erosion measurements are required in order to comprehend the erosional processes and propose effective and efficient conservation measures to mitigate surface erosion. Mitigating soil erosion, especially in Mediterranean countries such as Greece, is essential in order to maintain environmental and agricultural sustainability. In this paper, we present the Automated Soil Erosion Monitoring System (ASEMS) that measures surface soil erosion along with other factors that impact erosional process. Specifically, this system measures ground level changes (surface soil erosion), rainfall, air temperature, soil temperature and soil moisture. Another important innovation is that the data will be collected by remote communication. In addition, stakeholder’s awareness is a key factor to help reduce any environmental problem. The different dissemination activities that were utilized are described. The overall outcomes were the development of an innovative system that can measure erosion very accurately. These data from the system help study the process of erosion and find the best possible methods to reduce erosion. The dissemination activities enhance the stakeholder's and public's awareness on surface soil erosion problems and will lead to the adoption of more effective soil erosion conservation practices in Greece.

Keywords: soil management, climate change, new technologies, conservation practices

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Authors: C. D. Gomez-Esparza, Z. V. Hernandez-Castro, C. A. Rodriguez-Gonzalez, R. Martinez-Sanchez, A. Duarte-Moller

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Recently, the high entropy alloys (HEA) are the focus of attention in metallurgical and materials science due to their desirable and superior properties in comparison to conventional alloys. The HEA field has promoted the exploration of several compositions including the addition of non-metallic elements like carbon, which in traditional metallurgy is mainly used in the steel industry. The aim of this work was the synthesis of equiatomic FeCrNiMnTi high entropy alloys, with minor carbon content, by mechanical alloying and sintering. The effect of the addition of carbon nanotubes and graphite were evaluated by X-ray diffraction, scanning electron microscopy, and microhardness test. The structural and microstructural characteristics of the equiatomic alloys, as well as their hardness were compared with those of an austenitic AISI 321 stainless steel processed under the same conditions. The results showed that porosity in bulk samples decreases with carbon nanotubes addition, while the equiatomic composition favors the formation of titanium carbide and increased the AISI 321 hardness more than three times.

Keywords: carbon nanotubes, graphite, high entropy alloys, mechanical alloying

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Authors: Ergun Guntekin

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Elastic constants of Fir wood (Abies cilicica) have been investigated by means of ultrasound and compression tests. Three modulus of elasticity in principal directions (EL, ER, ET), six Poisson’s ratios (ʋLR, ʋLT, ʋRT, ʋTR, ʋRL, ʋTL) and three shear modules (GLR, GRT, GLT) were determined. 20 x 20 x 60 mm samples were conditioned at 65 % relative humidity and 20ºC before testing. Three longitudinal and six shear wave velocities propagating along the principal axes of anisotropy, and additionally, three quasi-shear wave velocities at 45° angle with respect to the principal axes of anisotropy were measured. 2.27 MHz longitudinal and 1 MHz shear sensors were used for obtaining sound velocities. Stress-strain curves of the samples in compression tests were obtained using bi-axial extensometer in order to calculate elastic constants. Test results indicated that most of the elastic constants determined in the study are within the acceptable range. Although elastic constants determined from ultrasound are usually higher than those determined from compression tests, the values of EL and GLR determined from compression tests were higher in the study. The results of this study can be used in the numerical modeling of elements or systems under load using Fir wood.

Keywords: compression tests, elastic constants, fir wood, ultrasound

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Authors: Tina Vuko, Marija Maretić, Marko Čular

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The aim of this study is to analyze the role and effectiveness of internal mechanism (audit committee) of corporate governance on credit institutions performance in Croatia. Based on research objective, sample of 78 credit institutions listed on Zagreb Stock Exchange, from 2007 to 2012, has been collected and efficiency index of audit committee (EIAC) has been created. Based on the sample and created EIAC, conclusions are as follows: audit committees of credit institutions have medium efficiency, based on EIAC measurement; there is a significant difference in audit committee effectiveness, in observed period; there is no positive relationship between audit committee effectiveness and credit institution performance; there is a significant difference between level of audit committee effectiveness and audit firm type. Future research should contain increased number of elements in EIAC creation and increased sample, for all obligators who need to establish audit committee.

Keywords: corporate governance, audit committee, financial institutions, efficiency index of audit committee

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Authors: F. Boukazouha, G. Poulin-Vittrant, M. Rguiti, M. Lethiecq

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Since its invention, by virtue of its remarkable features, the piezoelectric transformer (PT) has drawn the attention of the scientific community. In past years, it has been extensively studied and its performances have been continuously improved. Nowadays, such devices are designed in more and more sophisticated architectures with associated models describing their behavior quite accurately. However, the different studies usually carried out on such devices mainly focus on their electrical characteristics induced by direct piezoelectric effects such as voltage gain, efficiency or supplied power. In this work, we are particularly interested in the characterization of mechanical displacements induced by the inverse piezoelectric effect in a PT in vibration. For this purpose, a detailed three-dimensional finite element analysis is proposed to examine the mechanical behavior of a Rosen-type transformer made of a single bar of soft PZT (P191) and with dimensions 22mm×2.35mm×2.5mm. At the first three modes of vibration, output voltage and mechanical displacements ux, uy and uz along the length, the width and the thickness, respectively, are calculated. The amplitude of displacements varies in a range from a few nanometers to a few hundred nanometers. The validity of the simulations was successfully confirmed by experiments carried out on a prototype using a laser interferometer. A good match was observed between simulation and experimental results, especially for us at the second mode. Such 3D simulations thus appear as a helpful tool for a better understanding of mechanical phenomena in Rosen-type PT.

Keywords: piezoelectricity, gain, dispalcement, simulations

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Authors: Ali Yasin, Ali Kamran, Muhammad Safdar

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In order to reduce the hefty cost involved in terms of time and project cost, the development and application of advanced numerical tools to address the burn-back analysis problem in solid rocket motor design and development is the need of time. Several advanced numerical schemes have been developed in recent times, but their usage in the design of propellant grain of solid rocket motors is very rare. In this paper, an advanced numerical technique named the Level-Set method has been utilized for the burn-back analysis of star grain to study the effect of geometrical parameters on ballistic performance indicators such as solid loading, neutrality, and sliver percentage. In the level set technique, simple finite difference methods may fail quickly and require more sophisticated non-oscillatory schemes for feasible long-time simulation. For internal ballistic calculations, a simplified equilibrium pressure method is utilized. Preliminary results of the operative conditions, for all the combustion time, of star grain burn-back using level set techniques are compared with published results using CAD technique to test the developed numerical model.

Keywords: solid rocket motor, internal ballistic, level-set technique, star grain

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Authors: S. A. A. Nabeela Nasreen, S. Sundarrajan, S. A. Syed Nizar, Seeram Ramakrishna

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Metal-organic frameworks (MOFs) have attracted considerable interest due to its diverse pore size tunability, fascinating topologies and extensive uses in fields such as catalysis, membrane separation, chemical sensing, etc. Zeolitic imidazolate frameworks (ZIFs) are a class of MOF with porous crystals containing extended three-dimensional structures of tetrahedral metal ions (e.g., Zn) bridged by Imidazolate (Im). Selected ZIFs are used to separate solvent/solvent mixtures. A layer by layer formation of the nanocomposite of Zinc oxide (ZnO) and ZIF on a ceramic support using a solvothermal method was engaged and tested for target solvent/solvent separation. Metal oxide layer was characterized by XRD, SEM, and TEM to confirm the smooth and continuous coating for the separation process. The chemical composition of ZIF films was studied by using X-Ray absorption near-edge structure (XANES) spectroscopy. The obtained ceramic tube with metal oxide and ZIF layer coating were tested for its packing density, thickness, distribution of seed layers and variation of permeation rate of solvent mixture (isopropyl alcohol (IPA)/methyl isobutyl ketone (MIBK). Pervaporation technique was used for the separation to achieve a high permeation rate with separation ratio of > 99.5% of the solvent mixture.

Keywords: metal oxide, membrane, pervaporation, solvothermal, ZIF

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Authors: Sukron Makmun, Topan Firmandha, Siswanto

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Ultimate Strength Assessment on ship cross section in accordance with Biro Klasifikasi Indonesia (BKI) Rules for Hull, follows step by step incremental iterative approach. In this approach, ship cross section is divided into plate-stiffener combinations and hard corners element. The average stress-strain relationship (σ-ε) for all structural elements will be defined, where the subscript k refers to the modes 0, 1, 2, 3 or 4. These results would be verified with a commercial software calculation in similar cases. The numerical calculations of buckling strength are in accordance with the commercial software (GL Rules ND). Then the comparison of failure behaviours of stiffened panels and hard corners are presented. Where failure modes 3 are likely to occur first follows the failure mode 4 and the last one is the failure mode 1.

Keywords: ultimate strength assessment, BKI rules, incremental, plate-stiffener combination and hard corner, commercial software

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Authors: Hoyeon Park, Yunhwan Keon, Kyoung-Jae Kim

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Location Based Social Network services (LBSNs) is a new term that combines location based service and social network service (SNS). Unlike traditional SNS, LBSNs emphasizes empirical elements in the user's actual physical location. Point-of-Interest (POI) is the most important factor to implement LBSNs recommendation system. POI information is the most popular spot in the area. In this study, we would like to recommend POI to users in a specific area through recommendation system using collaborative filtering. The process is as follows: first, we will use different data sets based on Seoul and New York to find interesting results on human behavior. Secondly, based on the location-based activity information obtained from the personalized LBSNs, we have devised a new rating that defines the user's preference for the area. Finally, we have developed an automated rating algorithm from massive raw data using distributed systems to reduce advertising costs of LBSNs.

Keywords: location-based social network services, point-of-interest, recommender systems, business analytics

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Authors: Neda Nabid, Iman Hajirasouliha, Sanaz Shirinbar

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One of the most challenging issues in earthquake engineering is to find effective ways to reduce earthquake forces and damage to structural and non-structural elements under strong earthquakes. While friction dampers are the most efficient systems to improve the seismic performance of substandard structures, their optimum design is a challenging task. This research aims to find more appropriate slip load distribution pattern for efficient design of friction panels. Non-linear dynamic analyses are performed on 3, 5, 10, 15, and 20-story RC frame using Drain-2dx software to find the appropriate range of slip loads and investigate the effects of different distribution patterns (cantilever, uniform, triangle, and reverse triangle) under six different earthquake records. The results indicate that using triangle load distribution can significantly increase the energy dissipation capacity of the frame and reduce the maximum inter-storey drift, and roof displacement.

Keywords: friction panels, slip load, distribution patterns, RC frames, energy dissipation

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Authors: Amir Kavousifard, Lan Lin

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The objective of this study is to evaluate the effects of the detailing in the seismic design of reinforced concrete (RC) bridge columns on the blast load resistance. A generic two-span continuous RC bridge located in Victoria, British Columbia, which represents the highest seismicity in Canada, was examined in the study. The bridge superstructure consists of a single cell box girder while the substructure consists of two circular columns. The bridge was designed according to the 2006 Canadian Highway Bridge Design Code. More specifically, response spectrum analysis was performed to determine the seismic demands using CSI Bridge. The 3D blast load analysis is carried out in the platform of LS-DYNA. Two charge heights, i.e., one at the mid-height of the column and the other at the bottom of the column, are considered. For each height, three cases are analyzed in order to investigate the effects of standoff and charge weight on the structural response. The blast load resistance of the column is assessed in terms of the concrete failure mechanism, steel stress distribution, and column lateral displacement. The results from the study indicate that a column designed in accordance with the code requirements could survive during the blast attack. Spiral columns perform much better than tied columns. The results also show that the charge weight has more impact on the structural response than the standoff. These results are beneficial for the development of the Canadian standards for the design of bridges under blast loads.

Keywords: blast, bridge, charge, height, seismic, standoff

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Authors: Maged Assem Soliman Mossallam

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The conversion of solar thruster model to an upper stage hydrogen rocket is considered. Solar thruster categorization limits its capabilities to low and moderate thrust system with high specific impulse. The current study proposes a different concept for such systems by increasing the thrust which enables using as an upper stage rocket and for future launching purposes. A computational model for the thruster is discussed for solar thruster subsystems. The first module depends on ray tracing technique to determine the intercepted solar power by the hydrogen combustion chamber. The cavity receiver is modeled using finite volume technique. The final module imports the heated hydrogen properties to the nozzle using quasi one dimensional simulation. The probability of shock waves formulation inside the nozzle is almost diminished as the outlet pressure in space environment tends to zero. The computational model relates the high thrust hydrogen rocket conversion to the design parameters and operating conditions of the thruster. Three different designs for solar thruster systems are discussed. The first design is a low thrust high specific impulse design that produces about 10 Newton of thrust .The second one output thrust is about 250 Newton and the third design produces about 1000 Newton.

Keywords: space propulsion, hydrogen rocket, thrust, specific impulse

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Authors: Ya Lv

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This article presents the application of the semi-analytic method (SAM) in the thermal management solution (TMS) of the energy storage system (ESS). The TMS studied in this work is fluid cooling. In fluid cooling, both effective heat conduction and heat convection are indispensable due to the heat transfer from solid to fluid. Correspondingly, an efficient TMS requires a design investigation of the following parameters: fluid inlet temperature, ESS initial temperature, fluid flow rate, working c rate, continuous working time, and materials properties. Their variation induces a change of thermal performance in the battery module, which is usually evaluated by numerical simulation. Compared to complicated computation resources and long computation time in simulation, the SAM is developed in this article to predict the thermal influence within a few seconds. In SAM, a fast prediction model is reckoned by combining numerical simulation with theoretical/empirical equations. The SAM can explore the thermal effect of boundary parameters in both steady-state and transient heat transfer scenarios within a short time. Therefore, the SAM developed in this work can simplify the design cycle of TMS and inspire more possibilities in TMS design.

Keywords: semi-analytic method, fast prediction model, thermal influence of boundary parameters, energy storage system

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Authors: Azubuike Ekwere

Abstract:

The shallow and deep aquiferous horizons of the fractured and weathered crystalline basement Oban Massif of south-eastern Nigeria were studied during the dry and wet seasons. The criteria were ascertaining hydrochemistry relative to seasonal and spatial variations across the study area. Results indicate that concentrations of major cations and anions exhibit the order of abundance; Ca>Na>Mg>K and HCO3>SO4>Cl respectively, with minor variations across sampling seasons. Major elements Ca, Mg, Na and K were higher for the shallow aquifers than the deep aquifers across seasons. The major anions Cl, SO4, HCO3, and NO3 were higher for the deep aquifers compared to the shallow ones. Two water types were identified for both aquifer types: Ca-Mg-HCO3 and Ca-Na-Cl-SO4. Most of the parameters considered were within the international limits for drinking, domestic and irrigation purposes. Assessment by use of sodium absorption ratio (SAR), percent sodium (%Na) and the wilcox diagram reveals that the waters are suitable for irrigation purposes.

Keywords: shallow aquifer, deep aquifer, seasonal variation, hydrochemistry, Oban massif, Nigeria

Procedia PDF Downloads 662

Authors: Volkan Kaya, Ersin Elbasi

Abstract:

Watermarking and stenography are getting importance recently because of copyright protection and authentication. In watermarking we embed stamp, logo, noise or image to multimedia elements such as image, video, audio, animation and text. There are several works have been done in watermarking for different purposes. In this research work, we used watermarking techniques to embed patient information into the medical magnetic resonance (MR) images. There are two methods have been used; frequency domain (Digital Wavelet Transform-DWT, Digital Cosine Transform-DCT, and Digital Fourier Transform-DFT) and spatial domain (Least Significant Bits-LSB) domain. Experimental results show that embedding in frequency domains resist against one type of attacks, and embedding in spatial domain is resist against another group of attacks. Peak Signal Noise Ratio (PSNR) and Similarity Ratio (SR) values are two measurement values for testing. These two values give very promising result for information hiding in medical MR images.

Keywords: watermarking, medical image, frequency domain, least significant bits, security

Procedia PDF Downloads 288

Authors: R. Setino, I. M. Ambe, J. A Badenhorst-Weiss

Abstract:

The South African government supply chain management system is not adequately implemented in State Owned Enterprises (SOEs). There are weaknesses in the SOEs SCM enablers, strategies and policies. In addition, top management of SOEs still do not see SCM as strategic enough to deserve their attention, and therefore, there is very little support from top management, thus making it even difficult for SCM practitioners to execute their day to day functions, let alone delivering the letter and spirit of the relevant legislations. Supply chain strategies lack buy in from the top, and as a result senior SCM practitioners has not been involved in the corporate strategy. This has resulted in supply chain and corporate strategies being misaligned. Due to service delivery backlog, high level of corruption and continuous strikes across the country for better services it is inevitable that government leaders be more strategic about how South Africa can use SCM as a tool to improve service delivery. Consequently, there is a need to close the gap between the strategic level dealt by top management and the application of operational SCM concepts: the use of SCM concepts and, therefore, supply chain strategies – should be aligned with the corporate and business strategies in order to ensure the achievement of top level business objectives. This paper aims to explore supply chain practices in State Owned Enterprises (SOEs). The paper based on a conceptual review provides the status, trends and development and suggests a framework for aligning supply chain strategies and organizational strategies in an SOE environment.

Keywords: alignment, strategies, state owned enterprises, supply chain management, South Africa

Procedia PDF Downloads 420