Search results for: magneto-optic kerr effect (MOKE)

Authors: Imen Mejri, Ahmed Mahmoudi, Mohamed A. Abbassi, Ahmed Omri

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Thermal radiation plays a very important role in the heat transfer combination through the various components of the SOFC fuel cell operating at high temperatures. Lattice Boltzmann method is used for treating conduction-radiation heat transfer in the electrolyte. The thermal radiation heat transfer is coupled to the overall energy conservation equations through the divergence of the local radiative flux. The equation of energy in one dimension is numerically resolved by using the Lattice Boltzmann method. A computing program (FORTRAN) is developed locally for this purpose in order to obtain fields of temperature in every element of the cell. The parameters investigated are: functioning temperature, cell voltages and electrolyte thickness. The results show that the radiation effect increases with increasing the electrolyte thickness, also increases with increasing the functioning temperature and decreases with the increase of the voltage of the cell.

Keywords: SOFC, lattice Boltzmann method, conduction, radiation, planar medium.

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Authors: Sudip Ghosh, Probir Kumar Ghosh, Paramita Bhattacharjee

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Supercritical carbon dioxide extracts of Cinnamomum tamala (bay) leaves obtained at 55°C, 512 bar was found to have appreciable nutraceutical properties and was successfully employed as value-added ingredients in preparation of tofu. The bay leaf formulated tofu sample was evaluated for physicochemical properties (pH, texture analysis and lipid peroxidation), proximate analysis, phytochemical properties (total phenol content, antioxidant properties and total reducing sugar), microbial load and sensory profile analysis for a storage period of ten days, vis-à-vis an experimental control sample. These assays established the superiority of the tofu sample formulated with supercritical carbon dioxide extract of bay leaf over the control sample. Bay leaf extract formulated tofu is a new green functional food with promising nutraceutical benefits. 

Keywords: Cinnamomum tamala, Physicochemical properties Phytochemical properties, Supercritical carbon dioxide extraction, Tofu.

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Authors: A. Hemmati, H. Mirsaeedghazi, M. Aboonajmi

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Carrot juice is one of the most nutritious foods that are consumed around the world. Large particles in carrot juice causing turbid appearance make some problems in the concentration process such as off-flavor due to the large particles burnt on the walls of evaporators. Microfiltration (MF) is a pressure driven membrane separation method that can clarify fruit juices without enzymatic treatment. Fouling is the main problem in the membrane process causing reduction of permeate flux. Ultrasound as a cleaning technique was applied at 20 kHz to reduce fouling in membrane clarification of carrot juice using dead-end MF system with polyvinylidene fluoride (PVDF) membrane. Results showed that application of ultrasound waves reduce diphasic characteristic of carrot juice and permeate flux increased. Evaluation of different membrane fouling mechanisms showed that application of ultrasound waves changed creation time of each fouling mechanism. Also, its behavior was changed with varying transmembrane pressure.

Keywords: Carrot juice, dead end, microfiltration, ultrasound.

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Authors: Suleiman M. Elhamali, K. M. Etmimi, A. Usha

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The paper presents the results of microhardness and microstructure of low carbon steel surface melted using carbon dioxide laser with a wavelength of 10.6μm and a maximum output power of 2000W. The processing parameters such as the laser power, and the scanning rate were investigated in this study. After surface melting two distinct regions formed corresponding to the melted zone MZ, and the heat affected zone HAZ. The laser melted region displayed a cellular fine structures while the HAZ displayed martensite or bainite structure. At different processing parameters, the original microstructure of this steel (Ferrite+Pearlite) has been transformed to new phases of martensitic and bainitic structures. The fine structure and the high microhardness are evidence of the high cooling rates which follow the laser melting. The melting pool and the transformed microstructure in the laser surface melted region of carbon steel showed clear dependence on laser power and scanning rate.

Keywords: Carbon steel, laser surface melting, microstructure, microhardness.

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Authors: Mohsen Maadani, Seyed Ahmad Motamedi

Abstract:

The use of wireless technology in industrial networks has gained vast attraction in recent years. In this paper, we have thoroughly analyzed the effect of contention window (CW) size on the performance of IEEE 802.11-based industrial wireless networks (IWN), from delay and reliability perspective. Results show that the default values of CWmin, CWmax, and retry limit (RL) are far from the optimum performance due to the industrial application characteristics, including short packet and noisy environment. In this paper, an adaptive CW algorithm (payload-dependent) has been proposed to minimize the average delay. Finally a simple, but effective CW and RL setting has been proposed for industrial applications which outperforms the minimum-average-delay solution from maximum delay and jitter perspective, at the cost of a little higher average delay. Simulation results show an improvement of up to 20%, 25%, and 30% in average delay, maximum delay and jitter respectively.

Keywords: Average Delay, Contention Window, Distributed Coordination Function (DCF), Jitter, Industrial Wireless Network (IWN), Maximum Delay, Reliability, Retry Limit.

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Authors: Surendran M, Palani G. S, Nagesh R. Iyer

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Multi-site damage (MSD) has been a challenge to aircraft, civil and power plant structures. In real life components are subjected to cracking at many vulnerable locations such as the bolt holes. However, we do not consider for the presence of multiple cracks. Unlike components with a single crack, these components are difficult to predict. When two cracks approach one another, their stress fields influence each other and produce enhancing or shielding effect depending on the position of the cracks. In the present study, numerical studies on fracture analysis have been conducted by using the developed code based on the modified virtual crack closure integral (MVCCI) technique and finite element analysis (FEA) software ABAQUS for computing SIF of plates with multiple cracks. Various parametric studies have been carried out and the results have been compared with literature where ever available and also with the solution, obtained by using ABAQUS. By conducting extensive numerical studies expressions for SIF have been obtained for collinear cracks and non-aligned cracks.

Keywords: Crack interaction, Fracture mechanics, Multiple site damage, stress intensity factor, collinear cracks, non-aligned cracks.

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Authors: N. Khomarloo, F. Mousazadegan, M. Latifi, N. Hemmatinejad

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Recently, the utilization of reusable surgical gowns in order to decrease costs, environmental protection and enhance surgeon’s comfort is considered. One of the concerns in applying this kind of medical protective clothing is reduction of their resistance to bacterial penetration especially in wet state, after repeated laundering and sterilizing process. The purpose of this study is to investigate the effect of the laundering and sterilizing process on the reusable surgical gown’s resistance against bacterial wet penetration. To this end, penetration of Staphylococcus aureus bacteria in wet state after 70 washing and sterilizing cycles was evaluated on the two single-layer and three-layer reusable gowns. The outcomes reveal that up to 20 laundering and sterilizing cycles, protective property of samples improves due to fabric shrinkage, after that because of the fabric’s construction opening, the bacterial penetration increase. However, the three-layer gown presents higher protective performance comparing to the single-layer one.

Keywords: Reusable surgical gown, laundry, sterilization, wet bacterial penetration.

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Authors: Wen W. Zhang, Qian Chen

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Electron multiplying charge coupled devices (EMCCDs) have revolutionized the world of low light imaging by introducing on-chip multiplication gain based on the impact ionization effect in the silicon. They combine the sub-electron readout noise with high frame rates. Signal-to-noise Ratio (SNR) is an important performance parameter for low-light-level imaging systems. This work investigates the SNR performance of an EMCCD operated in Non-inverted Mode (NIMO) and Inverted Mode (IMO). The theory of noise characteristics and operation modes is presented. The results show that the SNR of is determined by dark current and clock induced charge at high gain level. The optimum SNR performance is provided by an EMCCD operated in NIMO in short exposure and strong cooling applications. In contrast, an IMO EMCCD is preferable.

Keywords: electron multiplying charge coupled devices, noise characteristics, operation modes, signal-to-noise ratioperformance

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Authors: E. Danso-Boateng

Abstract:

The effects of enzyme action and heat pretreatment on oil extraction yield from sunflower kernels were analysed using hexane extraction with Soxhlet, and aqueous extraction with incubator shaker. Ground kernels of raw and heat treated kernels, each with and without Viscozyme treatment were used. Microscopic images of the kernels were taken to analyse the visible effects of each treatment on the cotyledon cell structure of the kernels. Heat pretreated kernels before both extraction processes produced enhanced oil extraction yields than the control, with steam explosion the most efficient. In hexane extraction, applying a combination of steam explosion and Viscozyme treatments to the kernels before the extraction gave the maximum oil extractable in 1 hour; while for aqueous extraction, raw kernels treated with Viscozyme gave the highest oil extraction yield. Remarkable cotyledon cell disruption was evident in kernels treated with Viscozyme; whereas steam explosion and conventional heat treated kernels had similar effects.

Keywords: Enzyme-assisted aqueous and hexane extraction, heatpretreatment, sunflower cotyledon structure, sunflower oil extraction

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Authors: M.T. Shervani-Tabar, M. Rezaee, E. Madadi Kandjani

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Dynamics of a vapour bubble generated due to a high local energy input near a circular thin bronze plate in the absence of the buoyancy forces is numerically investigated in this paper. The bubble is generated near a thin bronze plate and during the growth and collapse of the bubble, it deforms the nearby plate. The Boundary Integral Equation Method is employed for numerical simulation of the problem. The fluid is assumed to be incompressible, irrotational and inviscid and the surface tension on the bubble boundary is neglected. Therefore the fluid flow around the vapour bubble can be assumed as a potential flow. Furthermore, the thin bronze plate is assumed to have perfectly plastic behaviour. Results show that the displacement of the circular thin bronze plate has considerable effect on the dynamics of its nearby vapour bubble. It is found that by decreasing the thickness of the thin bronze plate, the growth and collapse rate of the bubble becomes higher and consequently the lifetime of the bubble becomes shorter.

Keywords: Vapour Bubble, Thin Bronze Plate, Boundary Integral Equation Method.

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Authors: Balasubramanian P, Ligy Philip, S. Murty Bhallamudi

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In this study, cometabolic biodegradation of chloroform was experimented with mixed cultures in the presence of various organic solvents like methanol, ethanol, isopropanol, acetone, acetonitrile and toluene as these are predominant discharges in pharmaceutical industries. Toluene and acetone showed higher specific chloroform degradation rate when compared to other compounds. Cometabolic degradation of chloroform was further confirmed by observation of free chloride ions in the medium. An extended Haldane model, incorporating the inhibition due to chloroform and the competitive inhibition between primary substrates, was developed to predict the biodegradation of primary substrates, cometabolic degradation of chloroform and the biomass growth. The proposed model is based on the use of biokinetic parameters obtained from single substrate degradation studies. The model was able to satisfactorily predict the experimental results of ternary and quaternary mixtures. The proposed model can be used for predicting the performance of bioreactors treating discharges from pharmaceutical industries.

Keywords: Chloroform, Cometabolic biodegradation, Competitive inhibition, Extended Haldane model, Pharmaceuticalindustry.

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Authors: T. Pishbin, S.M.P. Firoozabadi, N. Jafarnia Dabanloo, F. Mohammadi, S. Koozehgari

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Heart-s electric field can be measured anywhere on the surface of the body (ECG). When individuals touch, one person-s ECG signal can be registered in other person-s EEG and elsewhere on his body. Now, the aim of this study was to test the hypothesis that physical contact (hand-holding) of two persons changes their heart rate variability. Subjects were sixteen healthy female (age: 20- 26) which divided into eight sets. In each sets, we had two friends that they passed intimacy test of J.sternberg. ECG of two subjects (each set) acquired for 5 minutes before hand-holding (as control group) and 5 minutes during they held their hands (as experimental group). Then heart rate variability signals were extracted from subjects' ECG and analyzed in linear feature space (time and frequency domain) and nonlinear feature space. Considering the results, we conclude that physical contact (hand-holding of two friends) increases parasympathetic activity, as indicate by increase SD1, SD1/SD2, HF and MF power (p<0.05) and decreases sympathetic activity, as indicate by decrease LF power (p<0.01) and LF/HF ratio (p<0.05).

Keywords: Autonomic nervous system (ANS), Hand- holding, Heart rate variability (HRV), Power spectral density analysis.

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Authors: U. Ben-Hamed, H. Seddighi, K. Thomas

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UK breweries generate extensive by products in the form of spent grain, slurry and yeast. Much of the spent grain is produced by large breweries and processed in bulk for animal feed. Spent brewery grains contain up to 20% protein dry weight and up to 60% fiber and are useful additions to animal feed. Bulk processing is economic and allows spent grain to be sold so providing an income to the brewery. A proportion of spent grain, however, is produced by small local breweries and is more variably distributed to farms or other users using intermittent collection methods. Such use is much less economic and may incur losses if not carefully assessed for transport costs. This study reports an economic returns of using wet brewery spent grain (WBSG) in animal feed using the Co-product Optimizer Decision Evaluator model (Cattle CODE) developed by the University of Nebraska to predict performance and economic returns when byproducts are fed to finishing cattle. The results indicated that distance from brewery to farm had a significantly greater effect on the economics of use of small brewery spent grain and that alternative uses than cattle feed may be important to develop.

Keywords: Animal Feed, Brewery Spent Grains, cattle CODE, Economic returns.

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Authors: D. Leskauskaite, I. Jasutiene, M. Kersiene, E. Malinauskyte, P. Matusevicius

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In vitro gastro-duodenal digestion model was used to investigate the changes of emulsions under digestion conditions. Oil in water emulsions stabilized by whey proteins (2%) and stabilized by whey proteins (2%) with addition of carboxymethyl cellulose (0.75%) as gelling agent of continuous phase were prepared at pH7. Both emulsions were destabilized under gastric conditions; however the protective role of carboxymethyl cellulose was indicated by recording delay of fat digestibility of this emulsion. In the presence of carboxymethyl cellulose whey proteins on the interfacial surface of droplets were more resistant to gastric degradation causing limited hydrolysis of fat due to the poor acceptability of lipids for the enzymes. Studies of emulsions using in vivo model supported results from in vitro studies. Lower content of triglycerides in blood serum and higher amount of fecal fat of rats were determined when rats were fed by diet containing emulsion made with whey proteins and carboxymethyl cellulose. 

Keywords: Digestibility, emulsions, lipids, rats.

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Authors: Granch Berhe Tseghai, Lodrick Wangatia Makokha

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Cotton dyeing using reactive dyes is one of the major water polluter; this is due to large amount of dye and salt remaining in effluent. Recent adverse climate change and its associated effect to human life have lead to search for more sustainable industrial production. Cationization of cotton to improve its affinity for reactive dye has been earmarked as a major solution for dyeing of cotton with no or less salt. Synthetic cationizing agents of ammonium salt have already been commercialized. However, in nature there are proteinous products which are rich in amino and ammonium salts which can be carefully harnessed to be used as cationizing agent for cotton. The hoofs and horns have successfully been used to cationize cotton so as to improve cotton affinity to the dye. The cationization action of the hoof and horn extract on cotton was confirmed by dyeing the pretreated fabric without salt and comparing it with conventionally dyed and untreated salt free dyed fabric. UV-VIS absorption results showed better dye absorption (62.5% and 50% dye bath exhaustion percentage for cationized and untreated respectively) while K/S values of treated samples were similar to conventional sample.

Keywords: Cationization, cotton, proteinous products, reactive dyes.

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Authors: Noraziah A. Y., Mashitah M. D., Subhash Bhatia

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Fructooligosaccharides derived from microbial enzyme especially from fungal sources has been received particular attention due to its beneficial effects as prebiotics and mass production. However, fungal fermentation is always cumbersome due to its broth rheology problem that will eventually affect the production of FOS. This study investigated the efficiency of immobilized cell system using rotating fibrous bed bioreactor (RFBB) in producing fructooligosaccharides (FOS). A comparative picture with respect to conventional stirred tank bioreactor (CSTB) and RFBB has been presented. To demonstrate the effect of agitation intensity and aeration rate, a laboratory-scale bioreactor 2.5 L was operated in three phases (high, medium, low) for 48 hours. Agitation speed has a great influence on P. simplicissimum fermentation for FOS production, where the volumetric FOS productivity using RFBB is increased with almost 4 fold compared to the FOS productivity in CSTB that only 0.319 g/L/h. Rate of FOS production increased up to 1.2 fold when immobilized cells system was employed at aeration rate similar to the freely suspended cells at 2.0 vvm.

Keywords: Fructooligosaccharides, immobilized, productivity, prebiotics.

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Authors: M. Raciti Castelli, S. De Betta, E. Benini

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This paper presents a means for reducing the torque variation during the revolution of a vertical-axis water turbine (VAWaterT) by increasing the blade number. For this purpose, twodimensional CFD analyses have been performed on a straight-bladed Darrieus-type rotor. After describing the computational model and the relative validation procedure, a complete campaign of simulations, based on full RANS unsteady calculations, is proposed for a three, four and five-bladed rotor architectures, characterized by a NACA 0025 airfoil. For each proposed rotor configuration, flow field characteristics are investigated at several values of tip speed ratio, allowing a quantification of the influence of blade number on flow geometric features and dynamic quantities, such as rotor torque and power. Finally, torque and power curves are compared for the three analyzed architectures, achieving a quantification of the effect of blade number on overall rotor performance.

Keywords: Vertical-Axis Water Turbine, rotor solidity, CFD, NACA 0025

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Authors: Shigeyuki Haruyama , Didik Nurhadiyanto, Moch Agus Choiron, Ken Kaminishi

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The previous study of new metal gasket that contact width and contact stress an important design parameter for optimizing metal gasket performance. The optimum design based on an elastic and plastic contact stress was founded. However, the influence of flange surface roughness had not been investigated thoroughly. The flange has many kinds of surface roughness. In this study, we conducted a gasket model include a flange surface roughness effect. A finite element method was employed to develop simulation solution. A uniform quadratic mesh used for meshing the gasket material and a gradually quadrilateral mesh used for meshing the flange. The gasket model was simulated by using two simulation stages which is forming and tightening simulation. A simulation result shows that a smoother of surface roughness has higher slope for force per unit length. This mean a squeezed against between flange and gasket will be strong. The slope of force per unit length for gasket 400-MPa mode was higher than the gasket 0-MPa mode.

Keywords: Surface roughness, flange, metal gasket, leakage, simulation.

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Authors: Hyun-Woo Cho

Abstract:

The fault detection and diagnosis of complicated production processes is one of essential tasks needed to run the process safely with good final product quality. Unexpected events occurred in the process may have a serious impact on the process. In this work, triangular representation of process measurement data obtained in an on-line basis is evaluated using simulation process. The effect of using linear and nonlinear reduced spaces is also tested. Their diagnosis performance was demonstrated using multivariate fault data. It has shown that the nonlinear technique based diagnosis method produced more reliable results and outperforms linear method. The use of appropriate reduced space yielded better diagnosis performance. The presented diagnosis framework is different from existing ones in that it attempts to extract the fault pattern in the reduced space, not in the original process variable space. The use of reduced model space helps to mitigate the sensitivity of the fault pattern to noise.

Keywords: Real-time Fault diagnosis, triangular representation of patterns in reduced spaces, Nonlinear kernel technique, multivariate statistical modeling.

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Authors: Rosidah Musa, Rezian-na Muhammad Kassim

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The purpose of this research is to disentangle and validate the underlying factorial-structure of Ecotourism Experiential Value (EEV) measurement scale and subsequently investigate its psychometric properties. The analysis was based on a sample of 225 eco-tourists, collected at the vicinity of Taman Negara National Park (TNNP) via interviewer-administered questionnaire. Exploratory factor analysis (EFA) was performed to determine the factorial structure of EEV. Subsequently, to confirm and validate the factorial structure and assess the psychometric properties of EEV, confirmatory factor analysis (CFA) was executed. In addition, to establish the nomological validity of EEV a structural model was developed to examine the effect of EEV on Total Eco-tourist Experience Quality (TEEQ). It is unveiled that EEV is a secondorder six-factorial structure construct and it scale has adequately met the psychometric criteria, thus could permit interpretation of results confidently. The findings have important implications for future research directions and management of ecotourism destination.

Keywords: ecotourism, experiential value, experience quality, national park,

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Authors: Sri Ratna Rahayu, Oktia Woro Kasmini Handayani, Lourensiana Y. S. Ngaga, Imade Sudana, Irwan Budiono

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Malaria is an infectious disease that still cannot be solved in Kori village, West Nusa Tenggara, Indonesia, where the most of people live in rumah panggung (Stilts House). The purpose of this study was to know whether there were the effects of rumah panggung environment, social culture, and behavior on malaria incidence in the Kori village. A cross-sectional study was performed to explore the effects of rumah panggung environment, social culture and behavior on malaria incidence. This study recruited 280 respondents, who live in the rumah panggung, permanent residents in Kori village, were age above 17 years old, and suffered from malaria in the past year. The collected data were analyzed with path analysis. The results of this study showed that the environment of rumah panggung and behavior have a direct effect on the incidence of malaria (p < 0.05). It could be concluded that improvement of environmental conditions of rumah panggung, sociocultural, and behavioral changes to maintain a healthy environment are needed to reduce the malaria incidence.

Keywords: Rumah panggung, socio cultural, behavior, malaria.

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Authors: G. Türkmen, Ö. Tekin, K. Kurtuluş, Y. Y. Yurtseven, M. Baran

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A scanning electron microscope (SEM) is a type of electron microscope mainly used in nanoscience and nanotechnology areas. Automatic image recognition and classification are among the general areas of application concerning SEM. In line with these usages, the present paper proposes a deep learning algorithm that classifies SEM images into nine categories by means of an online application to simplify the process. The NFFA-EUROPE - 100% SEM data set, containing approximately 21,000 images, was used to train and test the algorithm at 80% and 20%, respectively. Validation was carried out using a separate data set obtained from the Middle East Technical University (METU) in Turkey. To increase the accuracy in the results, the Inception ResNet-V2 model was used in view of the Fine-Tuning approach. By using a confusion matrix, it was observed that the coated-surface category has a negative effect on the accuracy of the results since it contains other categories in the data set, thereby confusing the model when detecting category-specific patterns. For this reason, the coated-surface category was removed from the train data set, hence increasing accuracy by up to 96.5%.

Keywords: Convolutional Neural Networks, deep learning, image classification, scanning electron microscope.

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Authors: Mohammad Gholizadeh, Khairun Yahya, Anita Talib, Omar Ahmad

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Macrobenthos distribution along the coastal waters of Penang National Park was studid to estimate the effect of different environmental parameters at three stations, during six sampling months, from June 2010 to April 2011. The aim of this survey was to investigate different environment stress over soft bottom polychaete community along Teluk Ketapang and Pantai Acheh (Penang National Park) over a year period. Variations in the polychaete community were evaluated using univariate and multivariate methods. A total of 604 individuals were examined which was grouped into 23 families. Family Nereidae was the most abundant (22.68%), followed by Spionidae (22.02%), Hesionidae (12.58%), Nephtylidae (9.27%) and Orbiniidae (8.61%). It is noticeable that good results can only be obtained on the basis of good taxonomic resolution. The maximum Shannon-Wiener diversity (H'=2.16) was recorded at distance 200m and 1200m (August 2010) in Teluk Ketapang and lowest value of diversity was found at distance 1200m (December 2010) in Teluk Ketapang.

Keywords: Polychaete assemblage, environment factor, Pantai Acheh, Teluk Ketapang.

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Authors: Shigeaki Sakurai, Makino Kyoko, Shigeru Matsumoto

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This paper proposes a method that predicts attractive evaluation objects. In the learning phase, the method inductively acquires trend rules from complex sequential data. The data is composed of two types of data. One is numerical sequential data. Each evaluation object has respective numerical sequential data. The other is text sequential data. Each evaluation object is described in texts. The trend rules represent changes of numerical values related to evaluation objects. In the prediction phase, the method applies new text sequential data to the trend rules and evaluates which evaluation objects are attractive. This paper verifies the effect of the proposed method by using stock price sequences and news headline sequences. In these sequences, each stock brand corresponds to an evaluation object. This paper discusses validity of predicted attractive evaluation objects, the process time of each phase, and the possibility of application tasks.

Keywords: Trend rule, frequent pattern, numerical sequential data, text sequential data, evaluation object.

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Authors: H. Paredes Gutiérrez, S. T. Pérez-Merchancano

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Motivated by recent experimental and theoretical developments, we investigate the influence of embedded quantum dot (EQD) of different geometries (lens, ring and pyramidal) in a double barrier heterostructure (DBH). We work with a general theory of quantum transport that accounts the tight-binding model for the spin dependent resonant tunneling in a semiconductor nanostructure, and Rashba spin orbital to study the spin orbit coupling. In this context, we use the second quantization theory for Rashba effect and the standard Green functions method. We calculate the current density as a function of the voltage without and in the presence of quantum dots. In the second case, we considered the size and shape of the quantum dot, and in the two cases, we worked considering the spin polarization affected by external electric fields. We found that the EQD generates significant changes in current when we consider different morphologies of EQD, as those described above. The first thing shown is that the current decreases significantly, such as the geometry of EQD is changed, prevailing the geometrical confinement. Likewise, we see that the current density decreases when the voltage is increased, showing that the quantum system studied here is more efficient when the morphology of the quantum dot changes.

Keywords: Quantum semiconductors, nanostructures, quantum dots, spin polarization.

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Authors: M. P. Chakravarthy, N. Ramanaiah, B. S. K.Sundara Siva Rao

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Taguchi approach was applied to determine the most influential control factors which will yield better tensile strength of the joints of pulse TIG welded 70/30 Cu-Ni alloy. In order to evaluate the effect of process parameters such as pulse frequency, peak current, base current and welding speed on tensile strength of Pulsed current TIG welded 70/30 Cu-Ni alloy of 5 mm thickness, Taguchi parametric design and optimization approach was used. Through the Taguchi parametric design approach, the optimum levels of process parameters were determined at 95% confidence level. The results indicate that the Pulse frequency, peak current, welding speed and base current are the significant parameters in deciding the tensile strength of the joint. The predicted optimal values of tensile strength of Pulsed current Gas tungsten arc welding (PC GTAW) of 70/30 Cu-Ni alloy welds are 368.8MPa.

Keywords: 70/30 Cu-Ni alloy, pulsed current GTAW, mechanical properties, Taguchi technique, analysis of variance.

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Authors: Raquel P. F. Guiné, Susana R. Matos, Daniela V. T. A. Costa, Fernando J. Gonçalves

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Because blueberries are worldwide recognized as a good source of beneficial components, their consumption has increased in the past decades, and so have the scientific works about their properties. Hence, this work was undertaken to evaluate the effect of some production and conservation factors on the properties of blueberries from cultivar Bluecrop. The physical and chemical analyses were done according to established methodologies and then all data was treated using software SPSS for assessment of the possible differences among the factors investigated and/or the correlations between the variables at study. The results showed that location of production influenced some of the berries properties (caliber, sugars, antioxidant activity, color and texture) and that the age of the bushes was correlated with moisture, sugars and acidity, as well as lightness. On the other hand, altitude of the farm only was correlated to sugar content. With regards to conservation, it influenced only anthocyanins content and DPPH antioxidant activity. Finally, the type of extract and the order of extraction had a pronounced influence on all the phenolic properties evaluated.

Keywords: Antioxidant activity, blueberry, conservation, geographical origin, phenolic compounds, statistical analysis.

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Authors: U. Şendurur, B. Nazlıoğlu

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Using Turkish data, in this study it is investigated that whether a firm’s ownership structure has an impact on its stock prices after the crisis. A linear regression model is conducted on the data of non-financial firms that are trading in Istanbul Stock Exchange 100 Index (ISE 100) index. The findings show that, all explanatory variables such as inside ownership, largest ownership, concentrated ownership, foreign shareholders, family controlled and dispersed ownership are not very important to explain stock prices after the crisis. Family controlled firms and concentrated ownership is positively related to stock price, dispersed ownership, largest ownership, foreign shareholders, and inside ownership structures have negative interaction between stock prices, but because of the p value is not under the value of 0.05 this relation is not significant. In addition, the analysis shows that, the shares of firms that have inside, largest and dispersed ownership structure are outperform comparing with the other firms. Furthermore, ownership concentrated firms outperform to family controlled firms.

Keywords: Financial crisis, ISE 100 Index, Ownership structure, Stock price.

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Authors: Soltani Amir, Hu Jiaxin

Abstract:

Determination of optimal parameters of a passive  control system device is the primary objective of this study.  Expanding upon the use of control devices in wind and earthquake  hazard reduction has led to development of various control systems.  The advantage of non-linearity characteristics in a passive control  device and the optimal control method using LQR algorithm are  explained in this study. Finally, this paper introduces a simple  approach to determine optimum parameters of a nonlinear viscous  damper for vibration control of structures. A MATLAB program is  used to produce the dynamic motion of the structure considering the  stiffness matrix of the SDOF frame and the non-linear damping  effect. This study concluded that the proposed system (variable  damping system) has better performance in system response control  than a linear damping system. Also, according to the energy  dissipation graph, the total energy loss is greater in non-linear  damping system than other systems.

 

Keywords: Passive Control System, Damping Devices, Viscous Dampers, Control Algorithm.

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Authors: Tarek M. Alguhane, Ayman H. Khalil, M. N. Fayed, Ayman M. Ismail

Abstract:

An existing RC building in Madinah is seismically evaluated with and without infill wall. Four model systems have been considered i.e. model I (no infill), model IIA (strut infill-update from field test), model IIB (strut infill- ASCE/SEI 41) and model IIC (strut infill-Soft storey- ASCE/SEI 41). Three dimensional pushover analyses have been carried out using SAP2000 software incorporating inelastic material behavior for concrete, steel and infill walls. Infill wall has been modeled as equivalent strut according to suggested equation matching field test measurements and to the ASCE/SEI 41 equation. The effect of building modeling on the performance point as well as capacity and demand spectra due to EQ design spectrum function in Madinah area has been investigated. The response modification factor (R) for the 5 story RC building is evaluated from capacity and demand spectra (ATC-40) for the studied models. The results are summarized and discussed.

Keywords: Infill wall, Pushover Analysis, Response Modification Factor, Seismic Assessment.

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