Search results for: vibration isolation performance

Authors: Benazzouz Djamel, Termeche Adel, Touati Youcef, Alem Said, Ouziala Mahdi

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This paper presents an approach which detect and isolate efficiently a fault in a system. This approach avoids false alarms, non-detections and delays in detecting faults. A study case have been proposed to show the importance of taking into consideration the uncertainties in the decision-making procedure and their effect on the degradation diagnostic performance and advantage of using Bond Graph (BG) for such degradation. The use of BG in the Linear Fractional Transformation (LFT) form allows generating robust Analytical Redundancy Relations (ARR’s), where the uncertain part of ARR’s is used to generate the residuals adaptive thresholds. The study case concerns an electromechanical system composed of a motor, a reducer and an external load. The aim of this application is to show the effectiveness of the BG-LFT approach to robust fault detection.

Keywords: bond graph, LFT, uncertainties, detection and faults isolation, ARR

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Authors: Ali Oveysi Sarabi

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The dimensions of nanostructures are in the range of inter-atomic spacing of the structures which makes them impossible to be modeled as a continuum. Nanoscale size-effects on vibration analysis of nanobeams embedded in an elastic medium is investigated using different types of beam theory. To this end, Eringen’s nonlocal elasticity is incorporated to various beam theories namely as Euler-Bernoulli beam theory (EBT), Timoshenko beam theory (TBT), Reddy beam theory (RBT), and Levinson beam theory (LBT). The surrounding elastic medium is simulated with both Winkler and Pasternak foundation models and the difference between them is studies. Explicit formulas are presented to obtain the natural frequencies of nanobeam corresponding to each nonlocal beam theory. Selected numerical results are given for different values of the non-local parameter, Winkler modulus parameter, Pasternak modulus parameter and aspect ratio of the beam that imply the effects of them, separately. It is observed that the values of natural frequency are strongly dependent on the stiffness of elastic medium and the value of the non-local parameter and these dependencies varies with the value of aspect ratio and mode number.

Keywords: nanobeams, free vibration, nonlocal elasticity, winkler foundation model, Pasternak foundation model, beam theories

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Authors: Lovorka Galetić, Ivana Načinović Braje, Nevenka Čavlek

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The purpose of this paper is to analyze the relationship between corporate culture and firm performance. Extensive theoretical and empirical evidence on this issue is provided. A quantitative methodology was used to explore relationship between corporate culture and performance among large Croatian companies. Corporate culture was explored by using Denison framework. The research revealed a positive, statistically significant relationship between mission and performance. Other dimensions of corporate culture (involvement, consistency and adaptability) show only partial relationship with performance.

Keywords: corporate culture, Croatia, Denison culture model, performance

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Authors: Konstantinos Sofianos, Michail Stefanidakis

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Nowadays, despite the great advances in technology, most educational frameworks lack a strong educational design basis. E-learning has become prevalent, but it faces various challenges such as student isolation and lack of quality in the learning process. An intelligent learning system provides a student with educational material according to their learning background and learning preferences. It records full information about the student, such as demographic information, learning styles, and academic performance. This information allows the system to be fully adapted to the student’s needs. In this paper, we propose a framework and an ontology for music education, consisting of the learner model and all elements of the learning process (learning objects, teaching methods, learning activities, assessment). This framework can be integrated into an intelligent learning system and used for music education in schools for the development of professional skills and beyond.

Keywords: intelligent learning systems, e-learning, music education, ontology, semantic web

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Authors: Jeet Shende, Leonid Shpanin, Misko Abramiuk, Mattew Goodwin, Nicholas Pickett

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Energy harvesting on board the Unmanned Ariel Vehicle (UAV) is one of the most rapidly growing emerging technologies and consists of the collection of small amounts of energy, for different applications, from unconventional sources that are incidental to the operation of the parent system or device. Different energy harvesting techniques have already been investigated in the multirotor drones, where the energy collected comes from the systems surrounding ambient environment and typically involves the conversion of solar, kinetic, or thermal energies into electrical energy. The energy harvesting from the vibrated propeller using the piezoelectric components inside the propeller has also been proven to be feasible. However, the impact on the UAV flight performance using this technology has not been investigated. In this contribution the impact on the multirotor drone operation has been investigated at different flight control configurations which support the efficient performance of the propeller vibration energy harvesting. The industrially made MANTIS X8-PRO octocopter frame kit was used to explore the octocopter operation which was modelled using SolidWorks 3D CAD package for simulation studies. The octocopter flight control strategy is developed through integration of the SolidWorks 3D CAD software and MATLAB/Simulink simulation environment for evaluation of the octocopter behaviour under different simulated flight modes and octocopter geometries. Analysis of the two modelled octocopter geometries and their flight performance is presented via graphical representation of simulated parameters. The possibility of not using the landing gear in octocopter geometry is demonstrated. The conducted study evaluates the octocopter’s flight control technique and its impact on the energy harvesting mechanism developed on board the octocopter. Finite Element Analysis (FEA) simulation results of the modelled octocopter in operation are presented exploring the performance of the octocopter flight control and structural configurations. Applications of both octocopter structures and their flight control strategy are discussed.

Keywords: energy harvesting, flight control modelling, object modeling, unmanned aerial vehicle

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Authors: Davide D’Aria, Paolo Falcone, Luigi Maggi, Aldo Cero, Giovanni Amoroso

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The paper presents a methodology for real-time structural health monitoring and geophysical applications. The key elements of the system are a high performance MIMO RADAR sensor, an optical camera and a dedicated set of software algorithms encompassing interferometry, tomography and photogrammetry. The MIMO Radar sensor proposed in this work, provides an extremely high sensitivity to displacements making the system able to react to tiny deformations (up to tens of microns) with a time scale which spans from milliseconds to hours. The MIMO feature of the system makes the system capable of providing a set of two-dimensional images of the observed scene, each mapped on the azimuth-range directions with noticeably resolution in both the dimensions and with an outstanding repetition rate. The back-scattered energy, which is distributed in the 3D space, is projected on a 2D plane, where each pixel has as coordinates the Line-Of-Sight distance and the cross-range azimuthal angle. At the same time, the high performing processing unit allows to sense the observed scene with remarkable refresh periods (up to milliseconds), thus opening the way for combined static and dynamic structural health monitoring. Thanks to the smart TX/RX antenna array layout, the MIMO data can be processed through a tomographic approach to reconstruct the three-dimensional map of the observed scene. This 3D point cloud is then accurately mapped on a 2D digital optical image through photogrammetric techniques, allowing for easy and straightforward interpretations of the measurements. Once the three-dimensional image is reconstructed, a 'repeat-pass' interferometric approach is exploited to provide the user of the system with high frequency three-dimensional motion/vibration estimation of each point of the reconstructed image. At this stage, the methodology leverages consolidated atmospheric correction algorithms to provide reliable displacement and vibration measurements.

Keywords: interferometry, MIMO RADAR, SAR, tomography

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Authors: Onmanee Prajuabjinda, Pakakrong Thondeeying, Jipisute Chunthorng-Orn, Bhanuz Dechayont, Arunporn Itharat

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A Thai medicinal preparation has been used for cancer treatment more than ten years ago in Khampramong Temple. Tectona grandis stem is one ingredient of this Thai medicinal remedy. The ethanolic extract of Tectona grandis stem showed the highest cytotoxic activities against human breast adenocarcinoma (MCF-7), but was less cytotoxic against large cell lung carcinoma (COR-L23) (IC50 = 3.92 and 7.78 µg/ml, respectively). It was isolated by bioassay-guided isolation method. Tectoquinone, a anthraquinone compound was isolated from this plant. This compound showed high specific cytotoxicity against human breast adenocarcinoma (MCF-7), but was less cytotoxic against large cell lung carcinoma (COR-L23)(IC50 =16.15 and 47.56 µg/ml or 72.67 and 214.00 µM, respectively). However, it showed less cytotoxic activity than the crude extract. In conclusion, tectoquinone as a main compound, is not the best cytotoxic compound from Tectona grandis, so there are more active cytotoxic compounds in this extract which should be isolated in the future. Moreover, tectoquinone displayed specific cytotoxicity against only human breast adenocarcinoma (MCF-7) which is a good criterion for cancer treatment.

Keywords: Tectona grandis, SRB assay, cytotoxicity, tectoquinone

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Authors: Igor Jerkovic

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Biodiversity of flora provides many different nectar sources for the bees. Unifloral honeys possess distinctive flavours, mainly derived from their nectar sources (characteristic volatile organic components (VOCs)). Specific or nonspecific VOCs (chemical markers) could be used for unifloral honey characterisation as addition to the melissopalynologycal analysis. The main honey volatiles belong, in general, to three principal categories: terpenes, norisoprenoids, and benzene derivatives. Some of these substances have been described as characteristics of the floral source, and other compounds, like several alcohols, branched aldehydes, and furan derivatives, may be related to the microbial purity of honey processing and storage conditions. Selection of the extraction method for the honey volatiles profiling should consider that heating of the honey produce different artefacts and therefore conventional methods of VOCs isolation (such as hydrodistillation) cannot be applied for the honey. Two-way approach for the isolation of the honey VOCs was applied using headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE). The extracts were analysed by gas chromatography and mass spectrometry (GC-MS). HS-SPME (with the fibers of different polarity such as polydimethylsiloxane/ divinylbenzene (PDMS/DVB) or divinylbenzene/carboxene/ polydimethylsiloxane (DVB/CAR/PDMS)) enabled isolation of high volatile headspace VOCs of the honey samples. Among them, some characteristic or specific compounds can be found such as 3,4-dihydro-3-oxoedulan (in Centaurea cyanus L. honey) or 1H-indole, methyl anthranilate, and cis-jasmone (in Citrus unshiu Marc. honey). USE with different solvents (mainly dichloromethane or the mixture pentane : diethyl ether 1 : 2 v/v) enabled isolation of less volatile and semi-volatile VOCs of the honey samples. Characteristic compounds from C. unshiu honey extracts were caffeine, 1H-indole, 1,3-dihydro-2H-indol-2-one, methyl anthranilate, and phenylacetonitrile. Sometimes, the selection of solvent sequence was useful for more complete profiling such as sequence I: pentane → diethyl ether or sequence II: pentane → pentane/diethyl ether (1:2, v/v) → dichloromethane). The extracts with diethyl ether contained hydroquinone and 4-hydroxybenzoic acid as the major compounds, while (E)-4-(r-1’,t-2’,c-4’-trihydroxy-2’,6’,6’-trimethylcyclo-hexyl)but-3-en-2-one predominated in dichloromethane extracts of Allium ursinum L. honey. With this two-way approach, it was possible to obtain a more detailed insight into the honey volatile and semi-volatile compounds and to minimize the risks of compound discrimination due to their partial extraction that is of significant importance for the complete honey profiling and identification of the chemical biomarkers that can complement the pollen analysis.

Keywords: honey chemical biomarkers, honey volatile compounds profiling, headspace solid-phase microextraction (HS-SPME), ultrasonic solvent extraction (USE)

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Authors: Firooz Bakhtiari-Nejad, Hamidreza Rostami, Meysam Mirzaee, Mona Zandbaf

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Dynamic tests are an important step of the design of engineering structures, because the accuracy of predictions of theoretical–numerical procedures can be assessed. In experimental test of moving loads that is one of the major research topics, the load is modeled as a simple moving mass or a small vehicle. This paper deals with the applicability of Non-Contact Moving Load (NML) for vibration analysis. For this purpose, an experimental set-up is designed to generate the different types of NML including constant and harmonic. The proposed method relies on pressurized air which is useful, especially when dealing with fragile or sensitive structures. To demonstrate the performance of this system, the set-up is employed for a modal analysis of a beam and detecting crack of the beam. The obtained results indicate that the experimental set-up for NML can be an attractive alternative to the moving load problems.

Keywords: experimental analysis, moving load, non-contact excitation, materials engineering

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Authors: Guerich Mohamed, Assaf Samir

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The application of viscoelastic materials in the form of constrained layers in mechanical structures is an efficient and cost-effective technique for solving noise and vibration problems. This technique requires a design tool to select the best location, type, and thickness of the damping treatment. This paper presents a finite element model for the vibration of beams partially or fully covered with a constrained viscoelastic damping material. The model is based on Bernoulli-Euler theory for the faces and Timoshenko beam theory for the core. It uses four variables: the through-thickness constant deflection, the axial displacements of the faces, and the bending rotation of the beam. The sandwich beam finite element is compatible with the conventional C1 finite element for homogenous beams. To validate the proposed model, several free vibration analyses of fully or partially covered beams, with different locations of the damping patches and different percent coverage, are studied. The results show that the proposed approach can be used as an effective tool to study the influence of the location and treatment size on the natural frequencies and the associated modal loss factors. Then, a parametric study regarding the variation in the damping characteristics of partially covered beams has been conducted. In these studies, the effect of core shear modulus value, the effect of patch size variation, the thickness of constraining layer, and the core and the locations of the patches are considered. In partial coverage, the spatial distribution of additive damping by using viscoelastic material is as important as the thickness and material properties of the viscoelastic layer and the constraining layer. Indeed, to limit added mass and to attain maximum damping, the damping patches should be placed at optimum locations. These locations are often selected using the modal strain energy indicator. Following this approach, the damping patches are applied over regions of the base structure with the highest modal strain energy to target specific modes of vibration. In the present study, a more efficient indicator is proposed, which consists of placing the damping patches over regions of high energy dissipation through the viscoelastic layer of the fully covered sandwich beam. The presented approach is used in an optimization method to select the best location for the damping patches as well as the material thicknesses and material properties of the layers that will yield optimal damping with the minimum area of coverage.

Keywords: finite element model, damping treatment, viscoelastic materials, sandwich beam

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Authors: Falek Kamel

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Various approaches are usually used in the dynamic analysis of beams vibrating transversally. For this, numerical methods allowing the solving of the general eigenvalue problem are utilized. The equilibrium equations describe the movement resulting from the solution of a fourth-order differential equation. Our investigation is based on the finite element method. The findings of these investigations are the vibration frequencies obtained by the Jacobi method. Two types of the elementary mass matrix are considered, representing a uniform distribution of the mass along with the element and concentrated ones located at fixed points whose number is increased progressively separated by equal distances at each evaluation stage. The studied beams have different boundary constraints representing several classical situations. Comparisons are made for beams where the distributed mass is replaced by n concentrated masses. As expected, the first calculus stage is to obtain the lowest number of beam parts that gives a frequency comparable to that issued from the Rayleigh formula. The obtained values are then compared to theoretical results based on the assumptions of the Bernoulli-Euler theory. These steps are used for the second type of mass representation in the same manner.

Keywords: structural elements, beams vibrating, dynamic analysis, finite element method, Jacobi method

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Authors: Bang-Fuh Chen, Chih-Chun Chu

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The flow induced cylinder vibration or earthquake-induced cylinder motion are moving in an arbitrary direction with time. The phenomenon of flow across cylinder is highly nonlinear and a linear-superposition of flow pattern across separated oscillating direction of cylinder motion is not valid to obtain the flow pattern across a cylinder oscillating in multiple directions. A novel finite difference scheme is developed to simulate the viscous flow across an arbitrary moving circular cylinder and we call this a complete 2D (two-dimensional) flow-cylinder interaction. That is, the cylinder is simultaneously oscillating in x- and y- directions. The time-dependent domain and meshes associated with the moving cylinder are mapped to a fixed computational domain and meshes, which are time independent. The numerical results are validated by several bench mark studies. Several examples are introduced including flow across steam-wise, transverse oscillating cylinder and flow across rotating cylinder and flow across arbitrary moving cylinder. The Morison’s formula can not describe the complex interaction phenomenon between cross flow and oscillating circular cylinder. And the completed 2D computational fluid dynamic analysis should be made to obtain the correct hydrodynamic force acting on the cylinder.

Keywords: 2D cylinder, finite-difference method, flow-cylinder interaction, flow induced vibration

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Authors: El-Sohaimy Sobhy A., Androsova Natalia, Toshev Abuvali Djabarovec

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The conditions of the isolation of proteins from the hemp seeds were optimized in the current work. Moreover, the physicochemical and functional properties of hemp protein isolate were evaluated for its potential application in food manufacturing. The elastin protein is the most predominant protein in the protein profile with a molecular weight of 58.1 KDa, besides albumin, with a molecular weight of 31.5 KDa. The FTIR spectrum detected the absorption peaks of the amide I in 1750 and 1600 cm⁻¹, which pointed to C=O stretching while N-H was stretching at 1650-1580 cm⁻¹. The peak at 3250 was related to N-H stretching of primary aliphatic amine (3400-3300 cm⁻¹), and the N-H stretching for secondary (II) amine appeared at 3350-3310 cm⁻¹. Hemp protein isolate (HPI) was showed high content of arginine (15.52 g/100 g), phenylalanine+tyrosine (9.63 g/100 g), methionine + cysteine (5.49 g/100 g), leucine + isoleucine (5.21 g/100 g) and valine (4.53 g/100 g). It contains a moderate level of threonine (3.29 g/100 g) and lysine (2.50 g/100 g), with the limiting amino acid being a tryptophan (0.22 g/100 g HPI). HPI showed high water-holding capacity (4.5 ± 2.95 ml/g protein) and oil holding capacity (2.33 ± 1.88 ml/g) values. The foaming capacity of HPI was increased with increasing the pH values to reach the maximum value at pH 11 (67.23±3.20 %). The highest emulsion ability index of HPI was noted at pH 9 (91.3±2.57 m2/g) with low stability (19.15±2.03).

Keywords: Cannabis sativa ssp., protein isolate, isolation conditions, amino acid composition, chemical properties, functional properties

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Authors: Nirmala Deenadayalu, Kwanele B. Mazibuko, Lethiwe D. Mthembu

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Sugarcane bagasse is the residue obtained after the extraction of sugar from the sugarcane. The main aim of this work was to produce catechol from sugarcane bagasse. The optimization of catechol production was investigated using a Box-Behnken design of experiments. The sugarcane bagasse was heated in a Parr reactor at a set temperature. The reactions were carried out at different temperatures (100-250) °C, catalyst loading (1% -10% KOH (m/v)) and reaction times (60 – 240 min) at 17 bar pressure. The solid and liquid fractions were then separated by vacuum filtration. The liquid fraction was analyzed for catechol using high-pressure liquid chromatography (HPLC) and characterized for the functional groups using Fourier transform infrared spectroscopy (FTIR). The optimized condition for catechol production was 175 oC, 240 min, and 10 % KOH with a catechol yield of 79.11 ppm. Since the maximum time was 240 min and 10 % KOH, a further series of experiments were conducted at 175 oC, 260 min, and 20 % KOH and yielded 2.46 ppm catechol, which was a large reduction in catechol produced. The HPLC peak for catechol was obtained at 2.5 min for the standards and the samples. The FTIR peak at 1750 cm⁻¹ was due to the C=C vibration band of the aromatic ring in the catechol present for both the standard and the samples. The peak at 3325 cm⁻¹ was due to the hydrogen-bonded phenolic OH vibration bands for the catechol. The ANOVA analysis was also performed on the set of experimental data to obtain the factors that most affected the amount of catechol produced.

Keywords: catechol, sugarcane bagasse, lignin, hydrothermal liquefaction

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Authors: Muhammad Akhtaruzzaman

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The impact of corporate environmental social and governance (ESG) on financial performance is often difficult to quantify despite the ESG related theories predict that ESG performance improves financial performance of a company. This research examines the link between corporate ESG performance and the financial performance of the NZX (New Zealand Stock Exchange) listed companies. For this purpose, this research utilizes mixed methods approaches to examine and understand this link. While quantitative results found no robust evidence of such a link, however, the qualitative analysis of content data suggests a strong cooccurrence exists between ESG performance and financial performance. The findings of this research have important implications for policymakers to support higher ESG-performing companies and for management practitioners to develop ESG-related strategies.

Keywords: ESG, financial performance, New Zealand firms, thematic analysis, mixed methods

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Authors: A. F. C. Nassar, D. K. Tessler, L. Okuda, C. Del Fava, D. P. Chiebao, A. H. C. N. Romaldini, A. P. Alvim, M. J. Sanchez-Vazquez, M. S. Rosa, J. C. Pompei, R. Harakava, M. C. S. Araujo, G. H. F. Marques, E. M. Pituco

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Glanders is a zoonotic disease of Equidae caused by the bacterium Burkholderia mallei presented in acute or chronic clinical forms with inflammatory nodules in the respiratory tract, lymphangitis and caseous lymph nodes. There is not a treatment with veterinary drugs to this life-threatening disease; thus, its occurrence must be notified to official animal health services and any infected animal must be eliminated. This study aims to detect B. mallei from horses euthanized in outbreaks of glanders in Brazil, providing a better understanding of the bacterial characteristics and determine a proper protocol for isolation. The work was carried out with the collaboration of the Ministry of Agriculture and the Sao Paulo State Animal Health Department, while its procedures were approved by the Committee of Ethics in Animal Experimentation from the Instituto Biologico (CETEA n°156/2017). To the present time, 16 horses from farms with outbreaks of glanders detected by complement fixation test (CFT) serology method were analyzed. During the necropsy, samples of possibly affected organs (lymph nodes, lungs, heart, liver, spleen, kidneys and trachea) were collected for bacterial isolation, molecular tests and pathology. Isolation was performed using two enriched mediums, a potato infusion agar with 5% sheep blood, 4% glycerol and antibiotics (penicilin100U/ mL), and another with the same ingredients except the antibiotic. A PCR protocol was modified for this study using primers design to identify a region of the Flip gen of B. mallei. Thru isolation, 12.5% (2/16) animals were confirmed positive using only the enriched medium with antibiotic and confirmed by PCR: from mediastinal and submandibular lymph nodes and lungs in one animal and from mediastinal lymph node in the other. The detection of the bacterium using PCR showed positivity of 100% (16/16) horses from 144 samples of organs. Pathology macroscopic lesions observed were catarrhal nasal discharge, fetlock ulcers, emaciation, lymphangitis in limbs, suppurative lymphangitis, lymph node enlargement, star shaped liver, and spleen scars, adherence of the renal capsule, pulmonary hemorrhage, and miliary nodules. Microscopic lesions were suppurative bronchopneumonia with microabscesses and Langhans giant cells in lungs; lymph nodes with abscesses and intense lymphoid reaction; hemosiderosis and abscesses in spleen. Positive samples on PCR will be sequenced later and analyzed comparing with previous records in the literature. A throughout description of the recent acute cases of glanders occurring in Brazil and characterization of the bacterium related will contribute to advances in the knowledge of the pathogenicity, clinical symptoms, and epidemiology of this zoonotic disease. Acknowledgment: This project is sponsored by FAPESP.

Keywords: equines, bacterial isolation, zoonosis, PCR, pathology

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Authors: Sílvia tuyà Viñas, Bruno Fernández-Valdés, Carla Pérez-Chirinos, Monica Morral-Yepes, Lucas del Campo Montoliu, Gerard Moras Feliu

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Some researchers stated that whole body vibration (WBV) generates postural destabilization, although there is no extensive research. Therefore, the aim of this study was to analyze movement variability when performing a half-squat with a different type of ballasts and rhythms with (V) and without (NV) WBV in male athletes using entropy. Twelve experienced in strength training males (age: 21.24  2.35 years, height: 176.83  5.80 cm, body mass: 70.63  8.58 kg) performed a half-squat with weighted vest (WV), dumbbells (D), and a bar with the weights suspended with elastic bands (B), in V and NV at 40 bpm and 60 bpm. Subjects performed one set of twelve repetitions of each situation, composed by the combination of the three factors. The movement variability was analyzed by calculating the Sample Entropy (SampEn) of the total acceleration signal recorded at the waist. In V, significant differences were found between D and WV (p<0.001; ES: 2.87 at 40 bpm; p<0.001; ES: 3.17 at 60 bpm) and between the B and WV at both rhythms (p<0.001; ES: 3.12 at 40 bpm; p<0.001; ES: 2.93 at 60 bpm) and a higher SampEn was obtained at 40 bpm with all ballasts (p<0.001; ES of WV: 1.22; ES of D: 4.49; ES of B: 4.03). No significant differences were found in NV. WBV is a disturbing and destabilizing stimulus. Strength and conditioning coaches should choose the combination of ballast and rhythm of execution according to the level and objectives of each athlete.

Keywords: accelerometry, destabilization, entropy, movement variability, resistance training

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Authors: A. I. A. Rahman, Sh-Hussain Salleh, K. Ahmad, K. Anuar

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Analysis of vocal fold vibration is essential for understanding the mechanism of voice production and for improving clinical assessment of voice disorders. This paper presents a Dynamic Time Warping (DTW) based approach to analyze and objectively classify vocal fold vibration patterns. The proposed technique was designed and implemented on a Glottal Area Waveform (GAW) extracted from high-speed laryngeal images by delineating the glottal edges for each image frame. Feature extraction from the GAW was performed using Linear Predictive Coding (LPC). Several types of voice reference templates from simulations of clear, breathy, fry, pressed and hyperfunctional voice productions were used. The patterns of the reference templates were first verified using the analytical signal generated through Hilbert transformation of the GAW. Samples from normal speakers’ voice recordings were then used to evaluate and test the effectiveness of this approach. The classification of the voice patterns using the technique of LPC and DTW gave the accuracy of 81%.

Keywords: dynamic time warping, glottal area waveform, linear predictive coding, high-speed laryngeal images, Hilbert transform

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Authors: B. G. Abiona, E. O. Fakoya, S. O. Adeogun, J. O. Blessed

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This study assessed the influence of communication pattern on agricultural employees’ job performance. Data were collected from 61 randomly selected respondents using a structured questionnaire. Perceived communication pattern that influence job performance include: the attitude of the administrators (x̅ = 3.41, physical barriers to communication flow among employees (x̅ = 3.21). Major challenges to respondents’ job performance were different language among employees (x̅ = 3.12), employees perception on organizational issues (x̅ = 3.09), networking (x̅ = 2.88), and unclear definition of work (x̅ = 2.74). A significant relationship was found between employees’ perceived communication pattern (r = 0.423, p < 0.00) and job performance. Information must be well designed in such a way that would positively influence employees’ job performance as this is essential in any agricultural organizations.

Keywords: communication pattern, job performance, agricultural employees, constraint, administrators, attitude

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Authors: Witthaya Mekhum, Wutthikorn Malikong

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The objective of this study is to investigate the increasing desktop computer performance after overclocking central processing unit or CPU by running a computer component at a higher clock rate (more clock cycles per second) than it was designed at the rate of 0.1 GHz for each level or 100 MHz starting at 4000 GHz-4500 GHz. The computer performance is tested for each level with 4 programs, i.e. Hyper PI ver. 0.99b, Cinebench R15, LinX ver.0.6.4 and WinRAR . After the CPU overclock, the computer performance increased. When overclocking CPU at 29% the computer performance tested by Hyper PI ver. 0.99b increased by 10.03% and when tested by Cinebench R15 the performance increased by 20.05% and when tested by LinX Program the performance increased by 16.61%. However, the performance increased only 8.14% when tested with Winrar program. The computer performance did not increase according to the overclock rate because the computer consists of many components such as Random Access Memory or RAM, Hard disk Drive, Motherboard and Display Card, etc.

Keywords: overclock, performance, central processing unit, computer

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Authors: Nicolò Vaiana, Giorgio Serino

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The nonlinear time history analysis of seismically base-isolated structures can require a significant computational effort when the behavior of each seismic isolator is predicted by adopting the widely used differential equation Bouc-Wen model. In this paper, a nonlinear exponential model, able to simulate the response of seismic isolation bearings within a relatively large displacements range, is described and adopted in order to reduce the numerical computations and speed up the nonlinear dynamic analysis. Compared to the Bouc-Wen model, the proposed one does not require the numerical solution of a nonlinear differential equation for each time step of the analysis. The seismic response of a 3d base-isolated structure with a lead rubber bearing system subjected to harmonic earthquake excitation is simulated by modeling each isolator using the proposed analytical model. The comparison of the numerical results and computational time with those obtained by modeling the lead rubber bearings using the Bouc-Wen model demonstrates the good accuracy of the proposed model and its capability to reduce significantly the computational effort of the analysis.

Keywords: base isolation, computational efficiency, nonlinear exponential model, nonlinear time history analysis

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Authors: Ghazanfar Ali, Fahad N Almajhdi

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This study provides data on the viral diagnosis and molecular epidemiology of influenza A(H3N2) virus isolated in Riyadh, Saudi Arabia. Nasopharyngeal aspirates from 80 clinically infected patients in the peak of the 2010-2011 winter seasons were processed for viral diagnosis by RT-PCR. Sequencing of entire HA and NA genes of representative isolates and molecular epidemiological analysis were performed. A total of 06 patients were positive for influenza A, B and respiratory syncytial viruses by RT-PCR assays; out of these only one sample was positive for influenza A(H3N2) by RT-PCR. Phylogenetic analysis of the HA and NA gene sequences showed identities higher than 99-98.8 % in both genes. They were also similar to reference isolates in HA sequences (99 % identity) and in NA sequences (99 % identity). Amino acid sequences predicted for the HA gene were highly identical to reference strains. The NA amino acid substitutions identified did not include the oseltamivir-resistant H275Y substitution. Conclusion: Viral isolation and RT-PCR together were useful for diagnosis of the influenza A (H3N2) virus. Variations in HA and NA sequences are similar to those identified in worldwide reference isolates and no drug resistance was found.

Keywords: influenza A (H3N2), genetic characterization, viral isolation, RT-PCR, Saudi Arabia

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Authors: Titanilla Komenda

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Human-machine-collaboration defines a direct interaction between humans and machines to fulfil specific tasks. Those so-called collaborative machines are used without fencing and interact with humans in predefined workspaces. Even though, human-machine-collaboration enables a flexible adaption to variable degrees of freedom, industrial applications are rarely found. The reasons for this are not technical progress but rather limitations in planning processes ensuring safety for operators. Until now, humans and machines were mainly considered separately in the planning process, focusing on ergonomics and system performance respectively. Within human-machine-collaboration, those aspects must not be seen in isolation from each other but rather need to be analysed in interaction. Furthermore, a simulation model is needed that can validate the system performance and ensure the safety for the operator at any given time. Following on from this, a holistic simulation model is presented, enabling a simulative representation of collaborative tasks – including both, humans and machines. The presented model does not only include a geometry and a motion model of interacting humans and machines but also a numerical behaviour model of humans as well as a Boole’s probabilistic sensor model. With this, error scenarios can be simulated by validating system behaviour in unplanned situations. As these models can be defined on the basis of Failure Mode and Effects Analysis as well as probabilities of errors, the implementation in a collaborative model is discussed and evaluated regarding limitations and simulation times. The functionality of the model is shown on industrial applications by comparing simulation results with video data. The analysis shows the impact of considering human factors in the planning process in contrast to only meeting system performance. In this sense, an optimisation function is presented that meets the trade-off between human and machine factors and aids in a successful and safe realisation of collaborative scenarios.

Keywords: human-machine-system, human-robot-collaboration, safety, simulation

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Authors: Hassan Saffari, Reza Askari Moghadam

Abstract:

In modern communication systems, it is highly demanded to achieve high performance with minimal power consumption. Low actuation voltage RF MEMS (Micro-Electro-Mechanical Systems) switches represent a significant advancement in this regard. These switches, with their ability to operate at lower voltages, offer promising solutions for enhancing connectivity while minimizing energy consumption. Microelectromechanical switches are good alternatives for electronic and mechanical switches due to their low insertion loss, high isolation, and fast switching speeds. They have attracted more attention in recent years. Most of the presented RF MEMS switches use electrostatic actuators due to their low power consumption. Low actuation voltage RF MEMS switches are among the important issues that have been investigated in research articles. The actuation voltage can be reduced by different methods. One usually implemented method is low spring constant structures. However, despite their numerous benefits, challenges remain in the widespread adoption of low-actuation voltage RF MEMS switches. Issues related to reliability, durability, and manufacturing scalability need to be addressed to realize their full potential in commercial applications. While overcoming certain challenges, their exceptional performance characteristics and compatibility with miniaturized electronic systems make them a promising choice for next-generation wireless communication and RF applications. In this paper, some previous works that proposed low-voltage actuation RF MEMS switches are investigated and analyzed.

Keywords: RF MEMS switches, low actuation voltage, small spring constant structures, electrostatic actuation

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Authors: Toufik Bensana, Medkour Mihoub, Slimane Mekhilef

Abstract:

The use of vibration analysis has been established as the most common and reliable method of analysis in the field of condition monitoring and diagnostics of rotating machinery. Rolling bearings cover a broad range of rotary machines and plays a crucial role in the modern manufacturing industry. Unfortunately, the vibration signals collected from a faulty bearing are generally nonstationary, nonlinear and with strong noise interference, so it is essential to obtain the fault features correctly. In this paper, a novel numerical analysis method based on local mean decomposition (LMD) is proposed. LMD decompose the signal into a series of product functions (PFs), each of which is the product of an envelope signal and a purely frequency modulated FM signal. The envelope of a PF is the instantaneous amplitude (IA), and the derivative of the unwrapped phase of a purely flat frequency demodulated (FM) signal is the IF. After that, the fault characteristic frequency of the roller bearing can be extracted by performing spectrum analysis to the instantaneous amplitude of PF component containing dominant fault information. The results show the effectiveness of the proposed technique in fault detection and diagnosis of rolling element bearing.

Keywords: fault diagnosis, rolling element bearing, local mean decomposition, condition monitoring

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Authors: Jin-Hyeong Park, Hong-Seok Kim, Jin-Hyeok Yim, Young-Ji Kim, Dong-Hyeon Kim, Jung-Whan Chon, Kun-Ho Seo

Abstract:

Salmonella contamination in chicken samples can cause major health problems in humans. However, not only the effects of antibiotic treatment during growth but also the impacts of poultry slaughter line on the prevalence of Salmonella in final chicken meat sold to consumers are unknown. In this study, we compared the isolation rates and antimicrobial resistance of Salmonella between antibiotic-free, conventional, conventional Korean native retail chicken meat samples and clonal divergence of Salmonella isolates by multilocus sequence typing. In addition, the distribution of extended-spectrum β-lactamase (ESBL) genes in ESBL-producing Salmonella isolates was analyzed. A total of 72 retail chicken meat samples (n = 24 antibiotic-free broiler [AFB] chickens, n = 24 conventional broiler [CB] chickens, and n = 24 conventional Korean native [CK] chickens) were collected from local retail markets in Seoul, South Korea. The isolation rates of Salmonella were 66.6% in AFB chickens, 45.8% in CB chickens, and 25% in CK chickens. By analyzing the minimum inhibitory concentrations of β -lactam antibiotics with the disc-diffusion test, we found that 81.2% of Salmonella isolates from AFB chickens, 63.6% of isolates from CB chickens, and 50% of isolates from CK chickens were ESBL producers; all ESBL-positive isolates had the CTX-M-15 genotype. Interestingly, all ESBL-producing Salmonella were revealed as ST16 by multilocus sequence typing. In addition, all CTX-M-15-positive isolates had the genetic platform of blaCTX-M gene (IS26-ISEcp1-blaCTX-M-15-IS903), to the best of our knowledge, this is the first report in Salmonella around the world. The Salmonella ST33 strain (S. Hadar) isolated in this study has never been reported in South Korea. In conclusion, our findings showed that antibiotic-free retail chicken meat products were also largely contaminated with ESBL-producing Salmonella and that their ESBL genes and genetic platforms were the same as those isolated from conventional retail chicken meat products.

Keywords: antibiotic-free poultry, conventional poultry, multilocus sequence typing, extended-spectrum β-lactamase, antimicrobial resistance

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Authors: Adhila Sandra Devy, Evangeline Syalomita Silitonga

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The landscape of corporate governance and accountability has led to the emergence of Integrated Reporting (IR) in response to the shortcomings of traditional reporting frameworks. Developed by The International Integrated Reporting Council (IIRC), IR aims to offer stakeholders a comprehensive view of a company’s performance by integrating financial and non-financial disclosures. This study analyzes literature on Integrated Reporting and Corporate Financial Performance from 2013 to 2024, employing a descriptive analysis methodology. 31 relevant articles were gathered from various sources, indicating a positive correlation between integrated reporting and financial performance, albeit without conclusive evidence of long-term impact.

Keywords: integrated reporting, corporate financial performance, corporate performance, firm performance, bibliometric analysis

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Authors: Nusrat Praween, Krishna Thej Pammi Guru, Palash Kumar Basu

Abstract:

Designing non-invasive biosensors for cancer diagnosis is essential for developing an affordable and specific tool to measure cancer-related exosome biomarkers. Exosomes, released by healthy as well as cancer cells, contain valuable information about the biomarkers of various diseases, including cancer. Despite the availability of various isolation techniques, ultracentrifugation is the standard technique that is being employed. Post isolation, exosomes are traditionally exposed to detergents for extracting their proteins, which can often lead to protein degradation. Further to this, it is very essential to develop a sensing platform for the quantification of clinically relevant proteins in a wider range to ensure practicality. In this study, exosomes were immobilized on the Au Screen Printed Electrode (SPE) using EDC/NHS chemistry to facilitate binding. After immobilizing the exosomes on the screen-printed electrode (SPE), we investigated the impact of the electric field by applying various voltages to induce exosome lysis and release their contents. The lysed solution was used for sensing TSG101, a crucial biomarker associated with various cancers, using both faradaic and non-faradaic electrochemical impedance spectroscopy (EIS) methods. The results of non-faradaic and faradaic EIS were comparable and showed good consistency, indicating that non-faradaic sensing can be a reliable alternative. Hence, the non-faradaic sensing technique was used for label-free quantification of the TSG101 biomarker. The results were validated using ELISA. Our electrochemical immunosensor demonstrated a consistent response of TSG101 from 125 pg/mL to 8000 pg/mL, with a detection limit of 0.125 pg/mL at room temperature. Additionally, since non-faradic sensing is label-free, the ease of usage and cost of the final sensor developed can be reduced. The proposed immunosensor is capable of detecting the TSG101 protein at low levels in healthy serum with good sensitivity and specificity, making it a promising platform for biomarker detection.

Keywords: biosensor, exosomes isolation on SPE, electric field lysis of exosome, EIS sensing of TSG101

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Authors: Mohammed Nishat, Ahmad Ghazali

Abstract:

This study empirically examines the corporate governance and firm performance, and tries to evaluate the governance, ownership and control related variables which are hypothesized to affect on firms performance. This study tries to evaluate the effectiveness of corporate governance mechanism to achieve high level performance among companies listed on the Karachi Stock Exchange (KSE) over the period from 2005 to 2008. To measure the firm performance level this research uses three measures of performance; Return on assets (ROA), Return on Equity (ROE) and Tobin’s Q. To link the performance of firms with the corporate governance three categories of corporate governance variables are tested which includes governance, ownership and control related variables. Fixed effect regression model is used to test the link between corporate governance and firm performance for 267 KSE listed Pakistani firms. The result shows that corporate governance variables such as percentage block holding by individuals have positive impact on firm performance. When CEO is also the chairperson of board then it is found that firm performance is adversely affected. Also negative relationship is found between share held by insiders and performance of firm. Leverage has negative impact on the performance of the firm and firm size is positively related with the firms performance.

Keywords: corporate governance, performance, agency cost, Karachi stock market

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Authors: Murast Dicleli, Ali SalemMilani

Abstract:

In this paper, a summary of analytical and experimental studies into the behavior of a new hysteretic damper, designed for seismic protection of structures is presented. The Multi-directional Torsional Hysteretic Damper (MRSD) is a patented invention in which a symmetrical arrangement of identical cylindrical steel cores is so configured as to yield in torsion while the structure experiences planar movements due to earthquake shakings. The new device has certain desirable properties. Notably, it is characterized by a variable and controllable-via-design post-elastic stiffness. The mentioned property is a result of MRSD’s kinematic configuration which produces this geometric hardening, rather than being a secondary large-displacement effect. Additionally, the new system is capable of reaching high force and displacement capacities, shows high levels of damping, and very stable cyclic response. The device has gone through many stages of design refinement, multiple prototype verification tests and development of design guide-lines and computer codes to facilitate its implementation in practice. Practicality of the new device, as offspring of an academic sphere, is assured through extensive collaboration with industry in its final design stages, prototyping and verification test programs.

Keywords: seismic, isolation, damper, adaptive stiffness

Procedia PDF Downloads 457