Search results for: process model

Authors: Yen-Ku Kuo, Chie-Bein Chen, Jyh-Yi Shih, Kuang-Yi Lin, Chien-Han Peng

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This study is primarily concerned with exploring what factors affect the consumer’s intention of using mobile phone e-book. In developing research structure, we adopted technology acceptance model (TAM) and Innovation Diffusion Theory (IDT) as a foundation. The analysis method of structural equation model (SEM) was used to carry out this study. Subjects were 261 users who are using or used the mobile phone e-book. The findings can be summed up as follows: (1) The subjective norm and job relevance has non-significant and positive influence to the perceived usefulness. This represents now the user are still in a small number and most of them used it in non-work related purpose. (2) The output quality, result demonstrability and perceived ease of use were confirmed to have positive and significant influence to the perceived usefulness. (3) The moderator “innovative diffusion” affects the relationship between the attitude and behavior intention. These findings could be a reference for the practice and future study to make further exploration.

Keywords: mobile phone e-book, technology acceptance model (TAM), innovation diffusion theory (IDT), structural equation model (SEM)

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Authors: E. O. George, P. Ojeaga, D. Odejimi, O. Mattehws

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Has macroeconomic management succeeded in making privatization promote growth in Africa? What are the probable strategies that should accompany the privatization reform process to promote growth in Africa? To what extent has the privatization process succeeded in attracting foreign direct investment to Africa? The study investigates the relationship between macroeconomic management and privatization. Many African countries have embarked on one form of privatization reform or the other since 1980 as one of the stringent conditions for accessing capital from the IMF and the World Bank. Secondly globalization and the gradually integration of the African economy into the global economy also means that Africa has to strategically develop its domestic market to cushion itself from fluctuations and probable contagion associated with global economic crisis that are always inevitable Stiglitz. The methods of estimation used are the OLS, linear mixed effects (LME), 2SLS and the GMM method of estimation. It was found that macroeconomic management has the capacity to affect the success of the privatization reform process. It was also found that privatization was not promoting growth in Africa; privatization could promote growth if long run growth strategies are implemented together with the privatization reform process. Privatization was also found not to have the capacity to attract foreign investment to many African countries.

Keywords: Africa, political economy, game theory, macroeconomic management and privatization

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Authors: Le Fu, Rui Wu, Gang Feng Liu, Jie Zhao

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Normally, impedance control methods are based on a model that connects a spring and damper in parallel. The series connection, namely the Maxwell model, has emerged as a counterpart and draw the attention of robotics researchers. In the theoretical analysis, it turns out that the two pattern are both equivalents to some extent, but notable differences of response characteristics exist, especially in the effect of damping viscosity. However, this novel impedance control design is lack of validation on realistic robot platforms. In this study, stability analysis and experimental evaluation are achieved using a 3-fingered Barrett® robotic hand BH8-282 endowed with tactile sensing, mounted on a torque-controlled lightweight and collaborative robot KUKA® LBR iiwa 14 R820. Object handover and incoming objects catching tasks are executed for validation and analysis. Experimental results show that the series connection pattern has much better performance in natural impact or shock absorption, which indicate promising applications in robots’ safe and physical interaction with humans and objects in various environments.

Keywords: impedance control, Maxwell model, force control, dexterous manipulation

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Authors: Peter O. Osifo, Hein W. J. P. Neomagus

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In this study, a predicted pH model was used to determine adsorption equilibrium properties of copper, lead, zinc and cadmium. Chitosan was prepared from the exoskeleton of Cape rock-lobsters, collected from the surroundings of Cape Town, South Africa. The beads were cross-linked with gluteraldehyde to restore its chemical stability in acid media. The chitosan beads were characterized; the beads water contents and pKa varied in the range of 90-96% and 4.3-6.0 respectively and the degree of crosslinking for the beads was 18%. A pH-model, which described the reversibility of the metal adsorbed onto the beads, was used to predict the equilibrium properties of copper, lead, zinc and cadmium adsorption onto the cross-linked beads. The model accounts for the effect of pH and the important model parameters; the equilibrium adsorption constant (Kads) and to a lesser extent the adsorbent adsorption capacity (qmax). The adsorption equilibrium constant for copper, lead, zinc and cadmium were found to be 2.58×10-3, 2.22×0-3, 9.55×0-3, and 4.79×0-3, respectively. The adsorbent maximum capacity was determined to be 4.2 mmol/g.

Keywords: chitosan beads, adsorption, heavy metals, waste water

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Authors: Jin-Uk Park

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Recently, the semiconductor industry is rapidly demanding complicated structures and mass production. From the point of view of mass production, the ETCH industry is concentrating on maintaining the ER (Etch rate) of the wafer edge constant regardless of changes over time. In this study, two major thermal factors affecting process were identified and controlled. First, the filler of the thermal pad was studied. Second, the significant difference of handling the thermal pad during PM was studied.

Keywords: etcher, thermal pad, wet cleaning, thermal conductivity

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Authors: Tanzeel Ur Rehman Khan, Franz Josef Behr, Phillip Davis

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Open source geospatial certifications are needed in geospatial technology education and industry sector. In parallel with proprietary software, free and open source software solutions become important in geospatial technology research and play an important role for the growth of the geospatial industry. ESRI, GISCI (GIS Certification Institute), ASPRS (American Society of Photogrammetry and remote sensing), and Meta spatial are offering certifications on proprietary and open source software. These are portfolio and competency based certifications depending on GIS Body of Knowledge (Bok). The analysis of these certification approaches might lead to the discovery of some gaps in them and will open a new way to develop certifications related to the geospatial open source (OS). This new certification will investigate the different geospatial competencies according to open source tools that help to identify geospatial professionals and strengthen the geospatial academic content. The goal of this research is to introduce a geospatial certification model based on geospatial technology competency model (GTCM).The developed certification will not only incorporate the importance of geospatial education and production of the geospatial competency-based workforce in universities and companies (private or public) as well as describe open source solutions with tools and technology. Job analysis, market analysis, survey analysis of this certification opens a new horizon for business as well.

Keywords: geospatial certification, open source, geospatial technology competency model, geoscience

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Authors: M. R. Ghasemi, R. Ghiasi, H. Varaee

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Surrogate model has received increasing attention for use in detecting damage of structures based on vibration modal parameters. However, uncertainties existing in the measured vibration data may lead to false or unreliable output result from such model. In this study, an efficient approach based on Monte Carlo simulation is proposed to take into account the effect of uncertainties in developing a surrogate model. The probability of damage existence (PDE) is calculated based on the probability density function of the existence of undamaged and damaged states. The kriging technique allows one to genuinely quantify the surrogate error, therefore it is chosen as metamodeling technique. Enhanced version of ideal gas molecular movement (EIGMM) algorithm is used as main algorithm for model updating. The developed approach is applied to detect simulated damage in numerical models of 72-bar space truss and 120-bar dome truss. The simulation results show the proposed method can perform well in probability-based damage detection of structures with less computational effort compared to direct finite element model.

Keywords: probability-based damage detection (PBDD), Kriging, surrogate modeling, uncertainty quantification, artificial intelligence, enhanced ideal gas molecular movement (EIGMM)

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Authors: Tai-Young Park, Yangjin Park

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Introduction: This study analyzed a family therapy case involving a female client in her thirties with panic disorder (PD) in South Korea. We identified five stages of the psychological process in the development of PD and examined external situations, family dynamics, and psychological experiences at each stage. Method: The client, mother, sister, and husband participated in therapy. Researchers analyzed the transcripts, notes, and video recordings of the therapy sessions. A thematic analysis was used to examine the data and display our findings using a network. Results: The developmental process of PD was as follows: (1) formation of anxiety, (2) sheltered life, (3) crisis, (4) loss of safe haven, and (5) inner breakdown. Conclusion: The family dynamics that developed as a result of coping with external situations in each stage contributed to clients’ psychological experiences. These psychological experiences triggered anxiety, which led to the development of PD. Moreover, this study empirically suggests that family dynamics can be associated with a person’s internal experiences that could lead to PD. Our findings highlight the significance of functional family dynamics and coping patterns when facing difficult external situations or crises.

Keywords: developmental process, family therapy, panic disorder, psychological dynamics

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Authors: Ahmed O. Babaleye, Rafet E. Kurt

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The global oil and gas industry is beginning to witness an increase in the number of installations moving towards decommissioning. Decommissioning of offshore installations is a complex, costly and hazardous activity, making safety one of the major concerns. Among existing removal options, complete and partial removal options pose the highest risks. Therefore, a dynamic risk model of the accidents from the two options is important to assess the risks on an overall basis. In this study, a risk-based safety model is developed to conduct quantitative risk analysis (QRA) for jacket structure systems failure. Firstly, bow-tie (BT) technique is utilised to model the causal relationship between the system failure and potential accident scenarios. Subsequently, to relax the shortcomings of BT, Bayesian Belief Networks (BBNs) were established to dynamically assess associated uncertainties and conditional dependencies. The BBN is developed through a similitude mapping of the developed bow-tie. The BBN is used to update the failure probabilities of the contributing elements through diagnostic analysis, thus, providing a case-specific and realistic safety analysis method when compared to a bow-tie. This paper presents the application of dynamic safety analysis to guide the allocation of risk control measures and consequently, drive down the avoidable cost of remediation.

Keywords: Bayesian belief network, offshore decommissioning, dynamic safety model, quantitative risk analysis

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Authors: Mehdi Salari

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This work introduces a new experimental method of martensite treatment contains accumulative roll-bonding used for producing the nano/ultrafine grained structure in low carbon steel. The ARB process up to 4 cycles was performed under unlubricated conditions, while the annealing process was carried out in the temperature range of 450–550°C for 30–100 min. The microstructures of the deformed and annealed specimens were investigated. The results showed that in the annealed specimen at 450°C for 30 or 60 min, recrystallization couldn’t be completed. Decrease in time and temperature intensified the volume fraction of the martensite cell blocks. Fully equiaxed nano/ultrafine grained ferrite was developed from the martensite cell blocks during the annealing at temperature around 500°C for 100 min.

Keywords: martensite process, accumulative roll bonding, recrystallization, nanostructure, plain carbon steel

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Authors: Seyed Ata Khalkhkali Sharifi, Gholamhossein Majzoubi, Farhad Abroush

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Developing mechanical properties of pure titanium has been reviewed in this paper by using ECAP process. At the first step of this article, the experimental samples were prepared as mentioned in the standards. Then pure grade 2 Ti was processed via equal-channel angular pressing (ECAp) for 2 passes following route-A at 400°C. After processing, the microstructural evolution, tensile, fatigue, hardness properties and wear behavior were investigated. Finally, the effect of ECAP process on these samples was analyzed. The results showed improvement in strength values with a slight decrease in ductility. The analysis on 30 points within the sample showed hardness increase in each pass. Also, it was concluded that fatigue properties were increased too.

Keywords: equal-channel angular pressing, titanium, mechanical behavior, engineering materials and applications

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Authors: Yuta Moriyama, Tsuyoshi Yamazaki, Etsuo Morishita

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Several aerodynamic devices currently attract engineers and research students. The plasma actuator is one of them, and it is very effective to control the flow. The actuator recovers a separated flow to an attached one. The actuator is also inversely applied to a spoiler. The model aircraft might be controlled by this actuator. We develop a model aircraft with the plasma actuator. Another interesting device is the Wells turbine which rotates in one direction. The present authors propose a bicycle with the Wells turbine in the wheels. Power reduction is measured when the turbine is driven by an electric motor at the exit of a wind tunnel. Several Watts power reduction might be possible. This means that the torque of the bike can be augmented by the turbine in the cross wind. These devices are tested in the wind tunnel with a three-component balance and the aerodynamic forces and moment are obtained. In this paper, we introduce these devices and their aerodynamic characteristics. The control force and moment of the plasma actuator are clarified and the power reduction of the bicycle is quantified.

Keywords: aerodynamics, model aircraft, plasma actuator, Wells turbine

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Authors: J. V. Thanikal, M. Torrijos, Philipe Sousbie, S. M. Rizwan, R. Senthil Kumar, Hatem Yezdi

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Co-digestion is one of the advantages of anaerobic digestion process because; several wastes having complimentary characteristics can be treated in a single process. The anaerobic co-digestion process, which can be defined as the simultaneous treatment of two –or more – organic biodegradable waste streams by anaerobic digestion offers great potential for the proper disposal of the organic fraction of solid waste coming from source or separate collection systems. The results of biogas production for sewage sludge, when used as a single substrate, were low (350ml/d), and also the biodegradation rate was slow. Sewage sludge as a co-substrate did not show much effect on biogas yield. The vegetable substrates (Potato, Carrot, Spinach) with a total charge of 27–36 g VS, with a HRT starting from 3 days and ending with 1 day, shown a considerable increase in biogas yield 3.5-5 l/d.

Keywords: anaerobic digestion, co-digestion, vegetable substrate, sewage sludge

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Authors: Ilsun Pang, Kwanghun Kim, Sungsun Baik

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Large diameter Si wafer is used as semiconductor substrate. Large diameter Si crystal ingot should be needed in order to increase wafer size. To make convection of large silicon melt stable, magnetic field is normally applied, but magnetic field is expensive and it is not proper to stabilize the large Si melt. To solve the problem, we propose a continuous Czochralski process which can be applied to small melt without magnetic field. We used granule poly, which has size distribution of 1~3 mm and is easily supplied in double crucible during silicon ingot growth. As the result, we produced 420 mm diameter ingot. In this paper, we describe an experimental study on crystal growth of large diameter silicon by Continuous Czochralski process.

Keywords: Czochralski, ingot, silicon crystal, wafer

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Authors: J. R. Wang, H. T. Lin, Y. Chiang, H. C. Chen, C. Shih

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Kuosheng Nuclear Power Plant (NPP) is located on the northern coast of Taiwan. Its nuclear steam supply system is a type of BWR/6 designed and built by General Electric on a twin unit concept. First, the methodology of Kuosheng NPP SPU (Stretch Power Uprate) safety analysis TRACE/SNAP model was developed in this research. Then, in order to estimate the safety of Kuosheng NPP under the more severe condition, the SBO (Station Blackout) + LOCA (Loss-of-Coolant Accident) transient analysis of Kuosheng NPP SPU TRACE/SNAP model was performed. Besides, the animation model of Kuosheng NPP was presented using the animation function of SNAP with TRACE/SNAP analysis results.

Keywords: TRACE, safety analysis, BWR/6, severe accident

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Authors: Hammad Majeed, Hanna Knuutila, Magne Hilestad, Hallvard Svendsen

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Formation of aerosols can cause serious complications in industrial exhaust gas CO2 capture processes. SO3 present in the flue gas can cause aerosol formation in an absorption based capture process. Small mist droplets and fog formed can normally not be removed in conventional demisting equipment because their submicron size allows the particles or droplets to follow the gas flow. As a consequence of this aerosol based emissions in the order of grams per Nm3 have been identified from PCCC plants. In absorption processes aerosols are generated by spontaneous condensation or desublimation processes in supersaturated gas phases. Undesired aerosol development may lead to amine emissions many times larger than what would be encountered in a mist free gas phase in PCCC development. It is thus of crucial importance to understand the formation and build-up of these aerosols in order to mitigate the problem.Rigorous modelling of aerosol dynamics leads to a system of partial differential equations. In order to understand mechanics of a particle entering an absorber an implementation of the model is created in Matlab. The model predicts the droplet size, the droplet internal variable profiles and the mass transfer fluxes as function of position in the absorber. The Matlab model is based on a subclass method of weighted residuals for boundary value problems named, orthogonal collocation method. The model comprises a set of mass transfer equations for transferring components and the essential diffusion reaction equations to describe the droplet internal profiles for all relevant constituents. Also included is heat transfer across the interface and inside the droplet. This paper presents results describing the basic simulation tool for the characterization of aerosols formed in CO2 absorption columns and gives examples as to how various entering droplets grow or shrink through an absorber and how their composition changes with respect to time. Below are given some preliminary simulation results for an aerosol droplet composition and temperature profiles. Results: As an example a droplet of initial size of 3 microns, initially containing a 5M MEA, solution is exposed to an atmosphere free of MEA. Composition of the gas phase and temperature is changing with respect to time throughout the absorber.

Keywords: amine solvents, emissions, global climate change, simulation and modelling, aerosol generation

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Authors: Yuzhi Cai

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In this paper, we discuss a Bayesian approach to quantile autoregressive (QAR) time series model estimation and forecasting. Together with a combining forecasts technique, we then predict USD to GBP currency exchange rates. Combined forecasts contain all the information captured by the fitted QAR models at different quantile levels and are therefore better than those obtained from individual models. Our results show that an unequally weighted combining method performs better than other forecasting methodology. We found that a median AR model can perform well in point forecasting when the predictive density functions are symmetric. However, in practice, using the median AR model alone may involve the loss of information about the data captured by other QAR models. We recommend that combined forecasts should be used whenever possible.

Keywords: combining forecasts, MCMC, predictive density functions, quantile forecasting, quantile modelling

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Authors: Zhengyi Kong, Seung-Eock Kim

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Single angle connections, which are bolted to the beam web and the column flange, are studied to investigate moment-rotation behavior. Elastic–perfectly plastic material behavior is assumed. ABAQUS software is used to analyze the nonlinear behavior of a single angle connection. The same geometric and material conditions with Yanglin Gong’s test are used for verifying finite element models. Since Kishi and Chen’s Power model and Lee and Moon’s Log model are accurate only for a limited range, simpler and more accurate hyperbolic function models are proposed. The equation for calculating rotation at ultimate moment is first proposed.

Keywords: finite element method, moment and rotation, rotation at ultimate moment, single-web angle connections

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Authors: Rafika Bayu Kusumandari, Istyarini, Ispen Safrel

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Character education will be more meaningful if carried out since early childhood. This is because early childhood education is the foundation of the formation of character. This study intends to find a model of character education in early childhood based on Javanese culture. In keeping with the focus of the study, long-term goals to be achieved through this research is to find once described the development of a model of character education in early childhood Javanese culture based in Semarang are then applied across early childhood education institutions in Semarang City. The specific objective of the study is: Describe the character models and management education in early childhood Java-based culture in Semarang City. The benefits of this research are; Provide an overview of the model and describe the management of character education in early childhood Java-based culture in Semarang City. Referring to the objectives of the research program was designed with a "Research and Development", meaning that a program of research followed by development programs for improvement or refinement. To produce a prototype model of character education in early childhood Java-based culture in the city, taken systematic measures in the form of the action, reflection, evaluation and innovation by applying qualitative research methods, descriptive, development, experimentation, and evaluation. This study aims to gain in-depth description of the model of character education in early childhood Java-based culture in the city of Semarang. The reason for the use of the use of qualitative methods researcher's knowledge, no study results and empirical research specifically about the model of character education in early childhood Java-based culture in the city of Semarang. On the implementation of character education early childhood adapted to the characteristics of each school and the emphasis of each agency arrangements for early childhood education, culture-based Java. Javanese culture should be introduced early in order not to erode the cultural lost outside the entrance as the era of globalization. In addition, Java is promoting a culture of courtesy and manners are very appropriate for the character formation of children of early age.

Keywords: education character, Javanese culture, childhood, character

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Authors: Mekdelawit Teferi Alamirew

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As a practical tool, the Geographical information system (GIS) was used for data integration, collection, management, analysis, and output presentation in pavement mangement systems . There are many GIS techniques to improve the maintenance activities like Dynamic segmentation and weighted overlay analysis which considers Multi Criteria Decision Making process. The results indicated that the developed MPI model works sufficiently and yields adequate output for providing accurate decisions. Hence considering multi criteria to prioritize the pavement sections for maintenance, as a result of the fact that GIS maps can express position, extent, and severity of pavement distress features more effectively than manual approaches, lastly the paper also offers digitized distress maps that can help agencies in their decision-making processes.

Keywords: pavement, flexible, maintenance, index

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Authors: Alexis Aldo Mendoza Villarroel, Ademir Clemente Villena Zevallos, Cristian Jose Lopez Del Alamo

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With the advancement of technology it is now possible to scan entire objects and obtain their digital representation by using point clouds or polygon meshes. However, some objects may be broken or have missing parts; thus, several methods focused on this problem have been proposed based on Geometric Deep Learning, such as GCNN, ACNN, PointNet, among others. In this article an approach from a different paradigm is proposed, using metric data structures to index global descriptors in the spectral domain and allow the recovery of a set of similar models in polynomial time; to later use the Iterative Close Point algorithm and recover the parts of the incomplete model using the geometry and topology of the model with less Hausdorff distance.

Keywords: 3D reconstruction method, point cloud completion, shape completion, similarity search

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Authors: Samy Madbouly

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The relaxation behavior of biorenewable castor oil-based polyurethane-lignin thin films synthesized in homogenous waterborne dispersions was investigated as a function of concentration at different temperatures and frequencies using broadband dielectric relaxation spectroscopy (BDRS). The molecular dynamics of the glass relaxation process and the local relaxation process of the PU-LS thin films were studied over a wide range of temperatures (-70 to 30 ℃) and frequencies (5 × 10−2 to 0.5 × 107 Hz) for different lignin concentration. Four relaxation processes have been observed namely; ?-, β-, γ-relaxations and ionic conductivity for pure castor oil-based PU and castor oil-lignin-based PU thin films at different temperatures and frequencies ranges. The Vogel-Fulcher-Tammann equation was found to be well described the temperature dependence of the characteristic relaxation times of the ?-relaxation process. However, on the other hand, the molecular dynamics of both β- and γ-relaxation processes were given by the Arrhenius equation. The incorporation of lignin into the castor oil-based PU significantly increased the glass transition temperature and primitivity of the thin films. In addition, the broadness, intensity, and molecular dynamics of the only observed ?-relaxation process were found to be strongly dependent on lignin concentration.

Keywords: castor oil, lignin, polyurethane, dielectric, dispersions

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Authors: Sirilak Areerachakul, Nat Ployong, Supayothin Na Songkla

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This research’s objective is to select the model with most accurate value by using Neural Network Technique as a way to filter potential students who enroll in IT course by electronic learning at Suan Suanadha Rajabhat University. It is designed to help students selecting the appropriate courses by themselves. The result showed that the most accurate model was 100 Folds Cross-validation which had 73.58% points of accuracy.

Keywords: artificial neural network, classification, students, e-learning

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Authors: Johnson Audu, Faisal Fairag

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In a bounded subset of R^d, d=2 or 3, we consider the Darcy-Forchheimer power model with the exponent 1 < m ≤ 2 for a single-phase strong-inertia fluid flow in a porous medium. Under necessary compatibility condition, and some mild regularity assumptions on the interior and the boundary data, we prove the existence and uniqueness of solution (u, p) in L^(m+1 ) (Ω)^d X (W^(1,(m+1)/m) (Ω)^d ⋂L_0^2 (Ω)^d) and its stability.

Keywords: porous media, power law, strong inertia, nonlinear, monotone type

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Authors: Ala Hanetite

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The purpose of this article is to present, by means of a model, the determinants of organisational culture which influence creativity and innovation. A literature study showed that a model, based on the open systems theory and the work of Schein, can offer a holistic approach in describing organisational culture. The relationship between creativity, innovation and culture is discussed in this context. Against the background of this model, the determinants of organisational culture were identified. The determinants are strategy, structure, support mechanisms, behaviour that encourages innovation, and open communication. The influence of each determinant on creativity and innovation is discussed. Values, norms and beliefs that play a role in creativity and innovation can either support or inhibit creativity and innovation depending on how they influence individual and group behaviour. This is also explained in the article.

Keywords: attitudes, creativity, innovation, organisational culture

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Authors: Pawinee Sorawech

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The purpose of this study was to investigate the quality improvement of painting assignments for grade 4-6 students by using PDCA cycle. This study employed a qualitative technique. Suan Sunandha Rajabhat University and its demonstration school were selected as the area of study. An in-depth interview was utilized. The findings revealed that model of PDCA cycle was a proper model to increase the quality of painting assignments for grade 4-6 students. The six steps of improvement included: studying the PDCA model, setting up a plan, determining the scope of work, creating a strategy, developing a quality for painting assignment, and coming up with a handbook for a quality improvement of painting assignment.

Keywords: quality, painting assignments, PDCA cycle, grade 4-6 students

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Authors: Heba M. Gobara, Ahmed A. M. El-Naggar, Rasha S. El-Sayed, Amal A. AlKahlawy

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In this study, metal organic framework (Cr-MIL-101) and TiO₂ nanoparticles were utilized as two semiconductors for water splitting process. The coupling of both semiconductors in order to improve the photocatalytic reactivity for the hydrogen production in presence of methanol as a hole scavenger under visible light (sunlight) has been performed. The forementioned semiconductors and the collected samples after water splitting application are characterized by several techniques viz., XRD, N₂ adsorption-desorption, TEM, ED, EDX, Raman spectroscopy and the total content of carbon. The results revealed an efficient yield of H₂ production with maximum purity 99.3% with the in-situ formation of graphene oxide nanosheets and multiwalled carbon nanotubes coated over the surface of the physically mixed Cr-MIL-101–TiO₂ system. The amount of H₂ gas produced was stored when using Cr-MIL-101 catalyst individually. The obtained data in this work provides promising candidate materials for pure hydrogen production as a clean fuel acquired from the water splitting process. In addition, the in-situ production of graphene nanosheets and carbon nanotubes is counted as promising advances for the presented process.

Keywords: hydrogen production, water splitting, photocatalysts, Graphene

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Authors: Muhammad Muzamal, Anders Rasmuson

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Wood material is extensively considered as a raw material for the production of bio-polymers, bio-fuels and value-added chemicals. However, the shortcoming in using wood as raw material is that the enzymatic hydrolysis of wood material is difficult because the accessibility of enzymes to hemicelluloses and cellulose is hindered by complex chemical and physical structure of the wood. The steam explosion (SE) pre-treatment improves the digestion of wood material by creating both chemical and physical modifications in wood. In this process, first, wood chips are treated with steam at high pressure and temperature for a certain time in a steam treatment vessel. During this time, the chemical linkages between lignin and polysaccharides are cleaved and stiffness of material decreases. Then the steam discharge valve is rapidly opened and the steam and wood chips exit the vessel at very high speed. These fast moving wood chips collide with each other and with walls of the equipment and disintegrate to small pieces. More damaged and disintegrated wood have larger surface area and increased accessibility to hemicelluloses and cellulose. The energy required for an increase in specific surface area by same value is 70 % more in conventional mechanical technique, i.e. attrition mill as compared to steam explosion process. The mechanism of wood disintegration during the SE pre-treatment is very little studied. In this study, we have simulated collision and impact of wood chips (dimension 20 mm x 20 mm x 4 mm) with each other and with walls of the vessel. The wood chips are simulated as a 3D orthotropic material. Damage and fracture in the wood material have been modelled using 3D Hashin’s damage model. This has been accomplished by developing a user-defined subroutine and implementing it in the FE software ABAQUS. The elastic and strength properties used for simulation are of spruce wood at 12% and 30 % moisture content and at 20 and 160 OC because the impacted wood chips are pre-treated with steam at high temperature and pressure. We have simulated several cases to study the effects of elastic and strength properties of wood, velocity of moving chip and orientation of wood chip at the time of impact on the damage in the wood chips. The disintegration patterns captured by simulations are very similar to those observed in experimentally obtained steam exploded wood. Simulation results show that the wood chips moving with higher velocity disintegrate more. Moisture contents and temperature decreases elastic properties and increases damage. Impact and collision in specific directions cause easy disintegration. This model can be used to efficiently design the steam explosion equipment.

Keywords: dynamic simulation, disintegration of wood, impact, steam explosion pretreatment

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Authors: Wael Elsaady, S. Olutunde Oyadiji, Adel Nasser

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The non-linear flow characteristics of magnetorheological (MR) fluids in MR dampers are studied via a coupled numerical approach that incorporates a two-phase flow model. The approach couples the Finite Element (FE) modelling of the damper magnetic circuit, with the Computational Fluid Dynamics (CFD) analysis of the flow field in the damper. The two-phase flow CFD model accounts for the effect of fluid compressibility due to the presence of liquid and gas in the closed domain of the damper. The dynamic mesh model included in ANSYS/Fluent CFD solver is used to simulate the movement of the MR damper piston in order to perform the fluid excitation. The two-phase flow analysis is studied by both Volume-Of-Fluid (VOF) model and mixture model that are included in ANSYS/Fluent. The CFD models show that the hysteretic behaviour of MR dampers is due to the effect of fluid compressibility. The flow field shows the distributions of pressure, velocity, and viscosity contours. In particular, it shows the high non-Newtonian viscosity in the affected fluid regions by the magnetic field and the low Newtonian viscosity elsewhere. Moreover, the dependence of gas volume fraction on the liquid pressure inside the damper is predicted by the mixture model. The presented approach targets a better understanding of the complicated flow characteristics of viscoplastic fluids that could be applied in different applications.

Keywords: viscoplastic fluid, magnetic FE analysis, computational fluid dynamics, two-phase flow, dynamic mesh, user-defined functions

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Authors: Rituparna Nath, Shawn J. Marshall

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Glaciers are one of the main sensitive climatic indicators, as they respond strongly to small climatic shifts. We develop a flow line model of glacier dynamics to simulate the past and future extent of glaciers in the Canadian Rocky Mountains, with the aim of coupling this model within larger scale regional climate models of glacier response to climate change. This paper will focus on glacier-climate modeling and reconstructions of glacier volume from the Little Ice Age (LIA) to present for Athabasca Glacier, Alberta, Canada. Glacier thickness, volume and mass change will be constructed using flow line modelling and examination of different climate scenarios that are able to give good reconstructions of LIA ice extent. With the availability of SPOT 5 imagery, Digital elevation models and GIS Arc Hydro tool, ice catchment properties-glacier width and LIA moraines have been extracted using automated procedures. Simulation of glacier mass change will inform estimates of meltwater run off over the historical period and model calibration from the LIA reconstruction will aid in future projections of the effects of climate change on glacier recession. Furthermore, the model developed will be effective for further future studies with ensembles of glaciers.

Keywords: flow line modeling, Athabasca Glacier, glacier mass balance, Remote Sensing, Arc hydro tool, little ice age

Procedia PDF Downloads 259