Search results for: theoretical model

Authors: Assabo Mohamed, Bile Mohamed, Ali Farah, Isman Souleiman, Olga Alos Ramos, Marie Cadet

Abstract:

The life of a nuclear power plant is regularly punctuated by short or long period outages to carry out maintenance operations and/or nuclear fuel reloading. During these stops periods, it is essential to conserve all the secondary circuit equipment to avoid corrosion priming. This kind of circuit is one of the main components of a nuclear reactor. Indeed, the conservation materials on shutdown of a nuclear unit improve circuit performance and reduce the maintenance cost considerably. This study is a part of the optimization of the dry preservation of equipment from the water station of the nuclear reactor. The main objective is to provide tools to guide Electricity Production Nuclear Centre (EPNC) in order to achieve the criteria required by the chemical specifications of conservation materials. A theoretical model of drying exchangers of water station is developed by the software Engineering Equation Solver (EES). It used to size requirements and air quality needed for dry conservation of equipment. This model is based on heat transfer and mass transfer governing the drying operation. A parametric study is conducted to know the influence of aerothermal factor taking part in the drying operation. The results show that the success of dry conservation of equipment of the secondary circuit of nuclear reactor depends strongly on the draining, the quality of drying air and the flow of air injecting in the secondary circuit. Finally, theoretical case study performed on EES highlights the importance of mastering the entire system to balance the air system to provide each exchanger optimum flow depending on its characteristics. From these results, recommendations to nuclear power plants can be formulated to optimize drying practices and achieve good performance in the conservation of material from the water at the stop position.

Keywords: dry conservation, optimization, sizing, water station

Procedia PDF Downloads 263

Authors: Irtaza M. Syed, Kaamran Raahemifar

Abstract:

This paper presents a model predictive control (MPC) of a utility interactive three phase inverter (TPI) for a photovoltaic (PV) system at commercial level. The proposed model uses phase locked loop (PLL) to synchronize TPI with the power electric grid (PEG) and performs MPC control in a dq reference frame. TPI model consists of boost converter (BC), maximum power point tracking (MPPT) control, and a three leg voltage source inverter (VSI). Operational model of VSI is used to synthesize sinusoidal current and track the reference. Model is validated using a 35.7 kW PV system in Matlab/Simulink. Implementation and results show simplicity and accuracy, as well as reliability of the model.

Keywords: model predictive control, three phase voltage source inverter, PV system, Matlab/simulink

Procedia PDF Downloads 596

Authors: Victor Onomza Waziri, John K. Alhassan, Idris Ismaila, Noel Dogonyara

Abstract:

This paper describes the problem of building secure computational services for encrypted information in the Cloud. Computing without decrypting the encrypted data; therefore, it meets the yearning of computational encryption algorithmic aspiration model that could enhance the security of big data for privacy or confidentiality, availability and integrity of the data and user’s security. The cryptographic model applied for the computational process of the encrypted data is the Fully Homomorphic Encryption Scheme. We contribute a theoretical presentations in a high-level computational processes that are based on number theory that is derivable from abstract algebra which can easily be integrated and leveraged in the Cloud computing interface with detail theoretic mathematical concepts to the fully homomorphic encryption models. This contribution enhances the full implementation of big data analytics based on cryptographic security algorithm.

Keywords: big data analytics, security, privacy, bootstrapping, Fully Homomorphic Encryption Scheme

Procedia PDF Downloads 484

Authors: Oscar Javier Montiel Mendez

Abstract:

The link between knowledge-creativity-innovation-entrepreneurship is well established, and broadly emphasized the importance of national innovation systems (NIS) as an approach stresses that the flow of information and technology among people, organizations and institutions are key to its process. Understanding the linkages among the actors involved in innovation is relevant to NIS. Creativity is supposed to fuel NIS, mainly focusing on a personal, group or organizational level, leaving aside the fourth one, as a national system. It is suggested that NIS takes Creativity for granted, an ex-ante stage already solved through some mechanisms, like programs for nurturing it at elementary and secondary schools, universities, or public/organizational specific programs. Or worse, that the individual already has this competence, and that the elements of the NIS will communicate between in a way that will lead to the creation of S curves, with an impact on national systems/programs on entrepreneurship, clusters, and the economy. But creativity constantly appears at any time during NIS, being the key input. Under an initial, exploratory, focused and refined literature review, based on Csikszentmihalyi’s systemic model, Amabile's componential theory, Kaufman and Beghetto’s 4C model, and the OECD’s (Organisation for Economic Co-operation and Development) NIS model (expanded), an NCS theoretical model is elaborated. Its suggested that its implementation could become a significant factor helping strengthen local, regional and national economies. The results also suggest that the establishment of a national creativity system (NCS), something that appears not been previously addressed, as a strategic/vital companion for a NIS, installing it not only as a national education strategy, but as its foundation, managing it and measuring its impact on NIS, entrepreneurship and the rest of the ecosystem, could make more effective public policies. Likewise, it should have a beneficial impact on the efforts of all the stakeholders involved and should help prevent some of the possible failures that NIS present.

Keywords: national creativity system, national innovation system, entrepreneurship ecosystem, systemic creativity

Procedia PDF Downloads 434

Authors: Kgolagano Mpejane

Abstract:

The study applies a New Institutional Economics (NIE) analytical framework to trade in developing economies by assessing the impacts of institutional quality and institutional quality distance on agricultural trade using a panel data of 15 Southern African Development Community (SADC) countries from the years 1991-2010. The issue of institutions on agricultural trade has not been accorded the necessary attention in the literature, particularly in developing economies. Therefore, the paper empirically tests the gravity model of international trade by measuring the impact of political, economic and legal institutions on intra SADC agricultural trade. The gravity model is noted for its exploratory power and strong theoretical foundation. However, the model has statistical shortcomings in dealing with zero trade values and heteroscedasticity residuals leading to biased results. Therefore, this study employs a two stage Heckman selection model with a Probit equation to estimate the influence of institutions on agricultural trade. The selection stages include the inverse Mills ratio to account for the variable bias of the gravity model. The Heckman model accounts for zero trade values and is robust in the presence of heteroscedasticity. The empirical results of the study support the NIE theory premise that institutions matter in trade. The results demonstrate that institutions determine bilateral agricultural trade on different margins with political institutions having positive and significant influence on bilateral agricultural trade flows within the SADC region. Legal and economic institutions have significant and negative effects on SADC trade. Furthermore, the results of this study confirm that institutional quality distance influences agricultural trade. Legal and political institutional distance have a positive and significant influence on bilateral agricultural trade while the influence of economic, institutional quality is negative and insignificant. The results imply that nontrade barriers, in the form of institutional quality and institutional quality distance, are significant factors limiting intra SADC agricultural trade. Therefore, gains from intra SADC agricultural trade can be attained through the improvement of institutions within the region.

Keywords: agricultural trade, institutions, gravity model, SADC

Procedia PDF Downloads 149

Authors: Ananya Rajagopal

Abstract:

The study is based on an analysis of qualitative data used to analyze the business performance of entrepreneurs in emerging markets based on core variables such as collective leadership in reference to social entrepreneurship and reverse accountability attributes of stakeholders. In-depth interviews were conducted with 25 emerging enterprises within Mexico across five industrial segments. The study has been conducted focusing on five major research questions, which helped in developing the grounded theory related to reverser accountability. The results of the study revealed that the traditional entrepreneurship model based on an individualistic leadership style is being replaced by a collective leadership model. The study focuses on the leadership styles within social enterprises aimed at enhancing managerial capabilities and competencies, stakeholder values, and entrepreneurial growth. The theoretical motivation of this study has been derived from stakeholder theory and agency theory.

Keywords: reverse accountability, social enterprises, collective leadership, grounded theory, social governance

Procedia PDF Downloads 122

Authors: Dino Carpentras, Alejandro Dinkelberg, Michael Quayle

Abstract:

Opinion dynamics models use an agent-based modeling approach to model people’s opinions. Model's properties are usually explored by testing the two 'degrees of freedom': the interaction rule and the network topology. The latter defines the connection, and thus the possible interaction, among agents. The interaction rule, instead, determines how agents select each other and update their own opinion. Here we show the existence of the third degree of freedom. This can be used for turning one model into each other or to change the model’s output up to 100% of its initial value. Opinion dynamics models represent the evolution of real-world opinions parsimoniously. Thus, it is fundamental to know how real-world opinion (e.g., supporting a candidate) could be turned into a number. Specifically, we want to know if, by choosing a different opinion-to-number transformation, the model’s dynamics would be preserved. This transformation is typically not addressed in opinion dynamics literature. However, it has already been studied in psychometrics, a branch of psychology. In this field, real-world opinions are converted into numbers using abstract objects called 'scales.' These scales can be converted one into the other, in the same way as we convert meters to feet. Thus, in our work, we analyze how this scale transformation may affect opinion dynamics models. We perform our analysis both using mathematical modeling and validating it via agent-based simulations. To distinguish between scale transformation and measurement error, we first analyze the case of perfect scales (i.e., no error or noise). Here we show that a scale transformation may change the model’s dynamics up to a qualitative level. Meaning that a researcher may reach a totally different conclusion, even using the same dataset just by slightly changing the way data are pre-processed. Indeed, we quantify that this effect may alter the model’s output by 100%. By using two models from the standard literature, we show that a scale transformation can transform one model into the other. This transformation is exact, and it holds for every result. Lastly, we also test the case of using real-world data (i.e., finite precision). We perform this test using a 7-points Likert scale, showing how even a small scale change may result in different predictions or a number of opinion clusters. Because of this, we think that scale transformation should be considered as a third-degree of freedom for opinion dynamics. Indeed, its properties have a strong impact both on theoretical models and for their application to real-world data.

Keywords: degrees of freedom, empirical validation, opinion scale, opinion dynamics

Procedia PDF Downloads 155

Authors: Amreth Chandrasehar

Abstract:

Machine Learning (ML) Models are developed and run in production to solve various use cases that help organizations to be more efficient and help drive the business. But this comes at a massive development cost and lost business opportunities. According to the Gartner report, 85% of data science projects fail, and one of the factors impacting this is not paying attention to Model Observability. Model Observability helps the developers and operators to pinpoint the model performance issues data drift and help identify root cause of issues. This paper focuses on providing insights into incorporating model observability in model development and operationalizing it in production.

Keywords: model observability, monitoring, drift detection, ML observability platform

Procedia PDF Downloads 112

Authors: Norhan El Dallal

Abstract:

The MENA region is a challenging, rapid urbanizing region, with a special profile; culturally, socially, economically and environmentally. Despite the diversity between different countries of the MENA region they all share similar urban challenges where extensive interventions are crucial. A climate sensitive region as the MENA region requires special attention for development, adaptation and mitigation. Integrating climatic and environmental parameters into the planning process to create a responsive urban form is the aim of this research in which “Parametric Urbanism” as a trend serves as a tool to reach a more sustainable urban morphology. An attempt to parameterize the relation between the climate and the urban form in a detailed manner is the main objective of the thesis. The aim is relating the different passive approaches suitable for the MENA region with the design guidelines of each and every part of the planning phase. Various conceptual scenarios for the network pattern and block subdivision generation based on computational models are the next steps after the parameterization. These theoretical models could be applied on different climatic zones of the dense communities of the MENA region to achieve an energy efficient neighborhood or city with respect to the urban form, morphology, and urban planning pattern. A final criticism of the theoretical model is to be conducted showing the feasibility of the proposed solutions economically. Finally some push and pull policies are to be proposed to help integrate these solutions into the planning process.

Keywords: parametric urbanism, climate responsive, urban form, urban and regional studies

Procedia PDF Downloads 481

Authors: A. S. Mousa, R. I. Rajab, A. A. Pinto

Abstract:

An envy behavioral game theoretical model with two types of homogeneous players is considered in this paper. The strategy space of each type of players is a discrete set with only two alternatives. The preferences of each type of players is given by a discrete utility function. All envy strategies that form Nash equilibria and the corresponding envy Nash domains for each type of players have been characterized. We use geometry to construct two dimensional envy tilings where the horizontal axis reflects the preference for players of type one, while the vertical axis reflects the preference for the players of type two. The influence of the envy behavior parameters on the Cartesian position of the equilibria has been studied, and in each envy tiling we determine the envy Nash equilibria. We observe that there are 1024 combinatorial classes of envy tilings generated from envy chromosomes: 256 of them are being structurally stable while 768 are with bifurcation. Finally, some conditions for the disparate envy Nash equilibria are stated.

Keywords: game theory, Nash equilibrium, envy Nash behavior, geometric tilings, bifurcation thresholds

Procedia PDF Downloads 230

Authors: S. A. Sadegh Zadeh, C. Kambhampati

Abstract:

Mathematical and computational modellings are the necessary tools for reviewing, analysing, and predicting processes and events in the wide spectrum range of scientific fields. Therefore, in a field as rapidly developing as neuroscience, the combination of these two modellings can have a significant role in helping to guide the direction the field takes. The paper combined mathematical and computational modelling to prove a weakness in a very precious model in neuroscience. This paper is intended to analyse all-or-none principle in Hodgkin-Huxley mathematical model. By implementation the computational model of Hodgkin-Huxley model and applying the concept of all-or-none principle, an investigation on this mathematical model has been performed. The results clearly showed that the mathematical model of Hodgkin-Huxley does not observe this fundamental law in neurophysiology to generating action potentials. This study shows that further mathematical studies on the Hodgkin-Huxley model are needed in order to create a model without this weakness.

Keywords: all-or-none, computational modelling, mathematical model, transmembrane voltage, action potential

Procedia PDF Downloads 617

Authors: Zakaria Khatraoui

Abstract:

Interlanguage has transcendentally capitalized its central role over a considerable metropolitan landscape. Either academically driven or pedagogically oriented, Interlanguage has principally floated as important than ever before. It academically probes theoretical and linguistic issues in the turf and further malleably flows from idea to reality to vindicate a bridging philosophy between theory and educational rehearsal. Characteristically, the present research grants a prolifically developed theoretical framework that is conversely sustained by empirical teaching practices, along with teasing apart the narrowly confined implementation. The focus of this interlingual study is placed stridently on syntactic errors projected in students’ writing as performance. To attain this endeavor, the paper appropriates qualitatively a plethora of focal methodological choices sponsored by a solid design. The steadily undeniable ipso facto to be examined is the creative sense of syntactic errors unequivocally endorsed by the tangible dominance of cognitively intralingual errors over linguistically interlingual ones. Subsequently, this paper attempts earnestly to highlight transferable implications worth indicating both theoretical and pedagogically professional principles. In particular, results are fundamentally relative to the scholarly community in a multidimensional sense to recommend actions of educational value.

Keywords: interlanguage, interference, error, writing

Procedia PDF Downloads 75

Authors: Jagdish Prasad Maurya, Sanjay Kumar Pandey

Abstract:

Inadequate understanding of the complex nature of flow features in tornado vortex is a major problem in modelling tornadoes. Tornadoes are violent atmospheric phenomenon that appear all over the world. Modelling tornadoes aim to reduce the loss of the human lives and material damage caused by the tornadoes. Dynamics of tornado is investigated by a numerical technique, the improved version of the projection method. In this paper, authors solve the problem for axisymmetric tornado vortex by the said method that uses a finite difference approach for getting an accurate and stable solution. The conclusions drawn are that large radial inflow velocity occurs near the ground that leads to increase the tangential velocity. The increased velocity phenomenon occurs close to the boundary and absolute maximum wind is obtained near the vortex core. The results validate previous numerical and theoretical models.

Keywords: computational fluid dynamics, mathematical model, Navier-Stokes equations, tornado

Procedia PDF Downloads 354

Authors: M. S. Gaafar, S. Y. Marzouk

Abstract:

Sodium borosilicate glasses doped with different content of NdF3 mol % have been prepared by rapid quenching method. Ultrasonic velocities (both longitudinal and shear) measurements have been carried out at room temperature and at ultrasonic frequency of 4 MHz. Elastic moduli, Debye temperature, softening temperature and Poisson's ratio have been obtained as a function of NdF3 modifier content. Results showed that the elastic moduli, Debye temperature, softening temperature and Poisson's ratio have very slight change with the change of NdF3 mol % content. Based on FTIR spectroscopy and theoretical (Bond compression) model, quantitative analysis has been carried out in order to obtain more information about the structure of these glasses. The study indicated that the structure of these glasses is mainly composed of SiO4 units with four bridging oxygens (Q4), and with three bridging and one nonbridging oxygens (Q3).

Keywords: borosilicate glasses, ultrasonic velocity, elastic moduli, FTIR spectroscopy, bond compression model

Procedia PDF Downloads 414

Authors: Lukas Reznak, Maria Reznakova

Abstract:

Recession of an economy has a profound negative effect on all involved stakeholders. It follows that timely prediction of recessions has been of utmost interest both in the theoretical research and in practical macroeconomic modelling. Current mainstream of recession prediction is based on standard OLS models of continuous GDP using macroeconomic data. This approach is not suitable for two reasons: the standard continuous models are proving to be obsolete and the macroeconomic data are unreliable, often revised many years retroactively. The aim of the paper is to explore a different branch of recession forecasting research theory and verify the findings on real data of the Czech Republic and Germany. In the paper, the authors present a family of discrete choice probit models with parameters estimated by the method of maximum likelihood. In the basic form, the probits model a univariate series of recessions and expansions in the economic cycle for a given country. The majority of the paper deals with more complex model structures, namely dynamic and bivariate extensions. The dynamic structure models the autoregressive nature of recessions, taking into consideration previous economic activity to predict the development in subsequent periods. Bivariate extensions utilize information from a foreign economy by incorporating correlation of error terms and thus modelling the dependencies of the two countries. Bivariate models predict a bivariate time series of economic states in both economies and thus enhance the predictive performance. A vital enabler of timely and successful recession forecasting are reliable and readily available data. Leading indicators, namely the yield curve and the stock market indices, represent an ideal data base, as the pieces of information is available in advance and do not undergo any retroactive revisions. As importantly, the combination of yield curve and stock market indices reflect a range of macroeconomic and financial market investors’ trends which influence the economic cycle. These theoretical approaches are applied on real data of Czech Republic and Germany. Two models for each country were identified – each for in-sample and out-of-sample predictive purposes. All four followed a bivariate structure, while three contained a dynamic component.

Keywords: bivariate probit, leading indicators, recession forecasting, Czech Republic, Germany

Procedia PDF Downloads 249

Authors: Ali Akbar

Abstract:

The importance of advancing women’s rights is closely intertwined with the development of civil society and the institutionalization of democracy in Middle Eastern countries. There is indeed an intimate relationship between the process of democratization and promoting gender equality, since democracy necessitates equality between men and women. In order to advance the issue of gender equality, what is required is a solid theoretical framework which has its roots in the reexamination of pre-modern interpretation of certain Qurʾānic passages that seem to have given men more rights than it gives women. This paper suggests that those Muslim scholars who adopt a contextualist approach to the Qurʾānic text and its interpretation provide a solid theoretical background for improving women’s rights. Indeed, the aim of the paper is to discuss how the contextualist approach to the Qurʾānic text and its interpretation given by a number of prominent scholars is capable of promoting the issue of gender equality. The paper concludes that since (1) much of the gender inequality found in the primary sources of Islam as well as pre-modern Muslim writings is rooted in the natural cultural norms and standards of early Islamic societies and (2) since the context of today’s world is so different from that of the pre-modern era, the proposed models provide a solid theoretical framework for promoting women’s rights and gender equality.

Keywords: contextualism, gender equality, Islam, the rights of women

Procedia PDF Downloads 326

Authors: Ali A. Hashim Habib, Ahmed A. Abdel-Rehim

Abstract:

Assuredly, massive amounts of wastes that are not utilized and dumped in uncontrolled dumpsites will be one of the major sources of diseases, fires, and emissions. With easy steps and minimum effort, energy can be produced from these gases. The present work introduces an experimental and theoretical analysis to estimate the amount of landfill gas and the corresponding energy which can be produced based on actual Egyptian municipal wastes composition. Two models were utilized and compared, EPA (Environmental Protection Agency) model and CDM (Clean Development Mechanisms) model to estimate methane generation rates and total CH4 emissions based on a particular landfill. The results showed that for every ton of municipal waste, 140 m3 of landfill gas can be produced. About 800 kW of electricity for a minimum of 24 years can be generated form one million ton of municipal waste. A total amount of 549,025 ton of carbon emission can be avoided during these 24 years.

Keywords: energy from landfill gases, landfill biogas, methane emission, municipal solid waste, renewable energy sources

Procedia PDF Downloads 226

Authors: Vangelis Papadimitropoulos

Abstract:

This paper is part of the research program “Techno-Social Innovation in the Collaborative Economy”, funded by the Hellenic Foundation for Research and Innovation (H.F.R.I.) for the years 2022-2024. The paper showcases the Open Food Network (OFN) as an open-sourced digital platform supporting short food supply chains in local agricultural production and consumption. The paper outlines the research hypothesis, the theoretical framework, and the methodology of research as well as the findings and conclusions. Research hypothesis: The model of open cooperativism as a vehicle for systemic change in the agricultural sector. Theoretical framework: The research reviews the OFN as an illustrative case study of the three-zoned model of open cooperativism. The OFN is considered a paradigmatic case of the model of open cooperativism inasmuch as it produces commons, it consists of multiple stakeholders including ethical market entities, and it is variously supported by local authorities across the globe, the latter prefiguring the mini role of a partner state. Methodology: Research employs Ernesto Laclau and Chantal Mouffe’s discourse analysis -elements, floating signifiers, nodal points, discourses, logics of equivalence and difference- to analyse the breadth of empirical data gathered through literature review, digital ethnography, a survey, and in-depth interviews with core OFN members. Discourse analysis classifies OFN floating signifiers, nodal points, and discourses into four themes: value proposition, governance, economic policy, and legal policy. Findings: OFN floating signifiers align around the following nodal points and discourses: “digital commons”, “short food supply chains”, “sustainability”, “local”, “the elimination of intermediaries” and “systemic change”. The current research identifies a lack of common ground of what the discourse of “systemic change” signifies on the premises of the OFN’s value proposition. The lack of a common mission may be detrimental to the formation of a common strategy that would be perhaps deemed necessary to bring about systemic change in agriculture. Conclusions: Drawing on Laclau and Mouffe’s discourse theory of hegemony, research introduces a chain of equivalence by aligning discourses such as “agro-ecology”, “commons-based peer production”, “partner state” and “ethical market entities” under the model of open cooperativism, juxtaposed against the current hegemony of neoliberalism, which articulates discourses such as “market fundamentalism”, “privatization”, “green growth” and “the capitalist state” to promote corporatism and entrepreneurship. Research makes the case that for OFN to further agroecology and challenge the current hegemony of industrial agriculture, it is vital that it opens up its supply chains into equivalent sectors of the economy, civil society, and politics to form a chain of equivalence linking together ethical market entities, the commons and a partner state around the model of open cooperativism.

Keywords: sustainability, the digital commons, open cooperativism, innovation

Procedia PDF Downloads 74

Authors: Lovorka Galetić, Ivana Načinović Braje, Nevenka Čavlek

Abstract:

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

Procedia PDF Downloads 529

Authors: Huang Bingling, Jia Yuhong, Liu Yanhui

Abstract:

As an important part of aircraft, landing gears are responsible for taking-off and landing function. In recent years, big airplane's structural quality increases a lot. As a result, landing gears have stricter technical requirements than ever before such as structure strength and etc. If the structural strength of the landing gear is enhanced through traditional methods like increasing structural quality, the negative impacts on the landing gear's function would be very serious and even counteract the positive effects. Thus, in order to solve this problem, the impact of pre-rotating of landing gears on performance of landing gears is studied from the theoretical and experimental verification in this paper. By increasing the pre-rotating speed of the wheel, it can improve the performance of the landing gear and reduce the structural quality, the force of joint parts and other properties. In addition, the pre-rotating of the wheels also has other advantages, such as reduce the friction between wheels and ground and extend the life of the wheel. In this paper, the impact of the pre-rotating speed on landing gears and the connecting between landing gears performance and pre-rotating speed would be researched in detail. This paper is divided into three parts. In the first part, large airplane landing gear model is built by CATIA and LMS. As most general landing gear type in big plane, four-wheel landing gear is picked as model. The second part is to simulate the process of landing in LMS motion, and study the impact of pre-rotating of wheels on the aircraft`s properties, including the buffer stroke, efficiency, power; friction, displacement and relative speed between piston and sleeve; force and load distribution of tires. The simulation results show that the characteristics of the different pre-rotation speed are understood. The third part is conclusion. Through the data of the previous simulation and the relationship between the pre-rotation speed of the aircraft wheels and the performance of the aircraft, recommended speed interval is proposed. This paper is of great theoretical value to improve the performance of large airplane. It is a very effective method to improve the performance of aircraft by setting wheel pre-rotating speed. Do not need to increase the structural quality too much, eliminating the negative effects of traditional methods.

Keywords: large airplane, landing gear, pre-rotating, simulation

Procedia PDF Downloads 343

Authors: A. El-S. Makled, M. K. Al-Tamimi

Abstract:

A mathematical model to predict the performance parameters (thrusts, chamber pressures, fuel mass flow rates, mixture ratios, and regression rates during firing time) of hybrid rocket motor (HRM) is evaluated. The internal ballistic (IB) hybrid combustion model assumes that the solid fuel surface regression rate is controlled only by heat transfer (convective and radiative) from flame zone to solid fuel burning surface. A laboratory HRM is designed, manufactured, and tested for low thrust profile space missions (10-15 N) and for validating the mathematical model (computer program). The polymer material and gaseous oxidizer which are selected for this experimental work are polymethyle-methacrylate (PMMA) and polyethylene (PE) as solid fuel grain and gaseous oxygen (GO₂) as oxidizer. The variation of various operational parameters with time is determined systematically and experimentally in firing of up to 20 seconds, and an average combustion efficiency of 95% of theory is achieved, which was the goal of these experiments. The comparison between recording fire data and predicting analytical parameters shows good agreement with the error that does not exceed 4.5% during all firing time. The current mathematical (computer) code can be used as a powerful tool for HRM analytical design parameters.

Keywords: hybrid combustion, internal ballistics, hybrid rocket motor, performance parameters

Procedia PDF Downloads 313

Authors: Narupot Putwattana

Abstract:

Changes in global situation such as environmental and economic crisis brought the new perspective for science education called integrative biology. STEM has been increasingly mentioned for several educational researches as the approach which combines the concept in Science (S), Technology (T), Engineering (E) and Mathematics (M) to apply in teaching and learning process so as to strengthen the 21st-century skills such as creativity and critical thinking. Recent studies demonstrated STEM as the pedagogy which described the engineering process along with the science classroom activities. So far, pedagogical contents for STEM explaining the content in biology have been scarce. A qualitative literature review was conducted so as to gather the articles based on electronic databases (google scholar). STEM education, engineering design, teaching and learning of biology were used as main keywords to find out researches involving with the application of STEM in biology teaching and learning process. All articles were analyzed to obtain appropriate teaching and learning model that unify the core concept of biology. The synthesized model comprised of engineering design, inquiry-based learning, biological prototype and biologically-inspired design (BID). STEM content and context integration were used as the theoretical framework to create the integrative biology instructional model for STEM education. Several disciplines contents such as biology, engineering, and technology were regarded for inquiry-based learning to build biological prototype. Direct and indirect integrations were used to provide the knowledge into the biology related STEM strategy. Meanwhile, engineering design and BID showed the occupational context for engineer and biologist. Technological and mathematical aspects were required to be inspected in terms of co-teaching method. Lastly, other variables such as critical thinking and problem-solving skills should be more considered in the further researches.

Keywords: biomimicry, engineering approach, STEM education, teaching and learning model

Procedia PDF Downloads 257

Authors: Jaouadi Imen, Ben Djemaa Raoudha, Ben Abdallah Hanene

Abstract:

The access to relevant information that is adapted to users’ needs, preferences and environment is a challenge in many applications running. That causes an appearance of context-aware systems. To facilitate the development of this class of applications, it is necessary that these applications share a common context meta-model. In this article, we will present our context meta-model that is defined using the OMG Meta Object facility (MOF). This meta-model is based on the analysis and synthesis of context concepts proposed in literature.

Keywords: context, meta-model, MOF, awareness system

Procedia PDF Downloads 562

Authors: Khalil Aryanfar, Shahrzad Sanjari, Elmira Hafez, Pariya Gholipor

Abstract:

The aim of this study was to Evaluate and compare the male and female students’ life skills of theoretical, technical-vocational and Job and Knowledge branches of secondary high school period. The research method is descriptive - survey Research population was 5892 students from three high schools in Tehran, sample size was determined 342 patients according to Morgan’s table and by stratified random sampling. The data collection tool was a questionnaire designed by the researchers that the reliability was more than 85/0 respectively. Data was anglicized by Kryskal Wallis and Mann-Whitney U-test. In three branches of theoretical, technical-vocational and Job and Knowledge The variables of academic achievement, the importance of organization, problem solving, seeking knowledge, good habits, mental and physical self-concept, family orientation and future orientation was not significant differences, in the variables of cooperative behavior, and ready for change was but significant differences. Variables such as academic achievement, seek knowledge, good habits, mental and physical, seeking direction to future cooperative behavior between boys and girls with the confidence of at least 95/0 and the variable ready for change among boys and girls by ensuring 0932 / There was an However, the importance of variables, problem solving, self-concept and family orientation was not significantly different.

Keywords: life skills, high school, theoretical, technical-vocational, job and knowledge

Procedia PDF Downloads 387

Authors: Sujoy Das, M. M. Ghosh

Abstract:

The thermal conductivity of a fluid can be significantly enhanced by dispersing nano-sized particles in it, and the resultant fluid is termed as "nanofluid". A theoretical model for estimating the thermal conductivity of a nanofluid has been proposed here. It is based on the mechanism that evenly dispersed nanoparticles within a nanofluid undergo Brownian motion in course of which the nanoparticles repeatedly collide with the heat source. During each collision a rapid heat transfer occurs owing to the solid-solid contact. Molecular dynamics (MD) simulation of the collision of nanoparticles with the heat source has shown that there is a pulse-like pick up of heat by the nanoparticles within 20-100 ps, the extent of which depends not only on thermal conductivity of the nanoparticles, but also on the elastic and other physical properties of the nanoparticle. After the collision the nanoparticles undergo Brownian motion in the base fluid and release the excess heat to the surrounding base fluid within 2-10 ms. The Brownian motion and associated temperature variation of the nanoparticles have been modeled by stochastic analysis. Repeated occurrence of these events by the suspended nanoparticles significantly contributes to the characteristic thermal conductivity of the nanofluids, which has been estimated by the present model for a ethylene glycol based nanofluid containing Cu-nanoparticles of size ranging from 8 to 20 nm, with Gaussian size distribution. The prediction of the present model has shown a reasonable agreement with the experimental data available in literature.

Keywords: brownian dynamics, molecular dynamics, nanofluid, thermal conductivity

Procedia PDF Downloads 371

Authors: Georgi Vendramin, Aurea Lúcia, Yamamoto, Carlos Itsuo, Souza Melegari, N. Samuel

Abstract:

This article describes the development of a model that uses a method where openings are represented by single glass and double glass. The model is based on a healthy balance equations purely theoretical and empirical data. Simplified equations are derived through a synthesis of the measured data obtained from meteorological stations. The implementation of the model in a design tool integrated buildings is discussed in this article, to better punctuate the requirements of comfort and energy efficiency in architecture and engineering. Sustainability, energy efficiency, and the integration of alternative energy systems and concepts are beginning to be incorporated into designs for new buildings and renovations to existing buildings. Few means have existed to effectively validate the potential performance benefits of the design concepts. It was used a method of degree-days for an assessment of the energy performance of a building showed that the design of the architectural design should always be considered the materials used and the size of the openings. The energy performance was obtained through the model, considering the location of the building Central Park Shopping Mall, in the city of Cascavel - PR. Obtained climatic data of these locations and in a second step, it was obtained the coefficient of total heat loss in the building pre-established so evaluating the thermal comfort and energy performance. This means that the more openings in buildings in Cascavel – PR, installed to the east side, they may be higher because the glass added to the geometry of architectural spaces will cause the environment conserve energy.

Keywords: sustainable design, energy modeling, design validation, degree-days methods

Procedia PDF Downloads 420

Authors: Ishay Wolf

Abstract:

In this study, the financial position of pension actors in the market during the pension system transition toward a more funded capitalized scheme is explored, mainly via an option benefit model. This is enabled by not considering the economy as a single earning cohort. We analytically demonstrate a socio-economic anomaly in the funded pension system, which is in favor of high earning cohorts on at the expense of low earning cohorts. This anomaly is realized by a lack of insurance and exposure to financial and systemic risks. Furthermore, the anomaly might lead to pension re-reform back to unfunded scheme, mostly due to political pressure. We find that a minimum pension guarantee is a rebalance mechanism to this anomaly, which increases the probability to of the sustainable pension scheme. Specifically, we argue that implementing the guarantee with an intra-generational, risk-sharing mechanism is the most efficient way to reduce the effect of this abnormality. Moreover, we exhibit the convergence process toward implementing minimum pension guarantee in many countries which have capitalized their pension systems during the last three decades, particularly among Latin America and CEE countries.

Keywords: benefits, pension scheme, put option, social security

Procedia PDF Downloads 122

Authors: Silvana Caglieri

Abstract:

Theoretical study of acetylation of p-methylaniline catalyzed by Cu2+ ions from the analysis of intermediate of the reaction was carried out. The study of acetylation of amines is of great interest by the utility of its products of reaction and is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process. Acetylation of amine is a nucleophilic substitution reaction. This reaction can be catalyzed by Lewis acid, metallic ion. In reaction mechanism, the metallic ion formed a complex with the oxygen of the acetic anhydride carbonyl, facilitating the polarization of the same and the successive addition of amine at the position to form a tetrahedral intermediate, determining step of the rate of the reaction. Experimental work agreed that this reaction takes place with the formation of a tetrahedral intermediate. In the present theoretical work were investigated the structure and energy of the tetrahedral intermediate of the reaction catalyzed by Cu2+ ions. Geometries of all species involved in the acetylation were made and identified. All of the geometry optimizations were performed by the method at the DFT/B3LYP level of theory and the method MP2. Were adopted the 6-31+G* basis sets. Energies were calculated using the Mechanics-UFF method. Following the same procedure it was identified the geometric parameters and energy of reaction intermediate. The calculations show 61.35 kcal/mol of energy for the tetrahedral intermediate and the energy of activation for the reaction was 15.55 kcal/mol.

Keywords: amides, amines, DFT, MP2

Procedia PDF Downloads 285

Authors: Aderonke Olaitan Adesina

Abstract:

Background: The paradigm shift to knowledge, as the key to organizational innovation and competitive advantage, has made the management of knowledge resources in organizations a mandate. A key component of the knowledge management (KM) cycle is knowledge creation, which is researched to be the result of the interaction between explicit and tacit knowledge. An effective knowledge creation process requires the use of the right model. The SECI (Socialisation, Externalisation, Combination, and Internalisation) model, proposed in 1995, is attested to be a preferred model of choice for knowledge creation activities. The model has, however, been criticized by researchers, who raise their concern, especially about its sequential nature. Therefore, this paper reviews extant literature on the practical application of each mode of the SECI model, from 1995 to date, with a view to ascertaining the relevance in modern-day KM practice. The study will establish the trends of use, with regards to the location and industry of use, and the interconnectedness of the modes. The main research question is, for organizational knowledge creation activities, is the SECI model indeed linear and sequential? In other words, does the model need to be reviewed in today’s KM practice? The review will generate a compendium of the usage of the SECI modes and propose a framework of use, based on the strength weaknesses opportunities and threats (SWOT) findings of the study. Method: This study will employ the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology to investigate the usage and SWOT of the modes, in order to ascertain the success, or otherwise, of the sequential application of the modes in practice from 1995 to 2019. To achieve the purpose, four databases will be explored to search for open access, peer-reviewed articles from 1995 to 2019. The year 1995 is chosen as the baseline because it was the year the first paper on the SECI model was published. The study will appraise relevant peer-reviewed articles under the search terms: SECI (or its synonym, knowledge creation theory), socialization, externalization, combination, and internalization in the title, abstract, or keywords list. This review will include only empirical studies of knowledge management initiatives in which the SECI model and its modes were used. Findings: It is expected that the study will highlight the practical relevance of each mode of the SECI model, the linearity or not of the model, the SWOT in each mode. Concluding Statement: Organisations can, from the analysis, determine the modes of emphasis for their knowledge creation activities. It is expected that the study will support decision making in the choice of the SECI model as a strategy for the management of organizational knowledge resources, and in appropriating the SECI model, or its remodeled version, as a theoretical framework in future KM research.

Keywords: combination, externalisation, internalisation, knowledge management, SECI model, socialisation

Procedia PDF Downloads 358

Authors: Isaac Kofi Mensah

Abstract:

Public sector organizations, ministries, departments and local government agencies are adopting e-government as a means to provide efficient and quality service delivery to citizens. The purpose of this research paper is to examine the extent to which perceived usefulness (PU) of e-government services moderates between perceived ease-of-use (PEOU) of e-government services and intention to use (IU) e-government services in Ghana. A structured research questionnaire instrument was developed and administered to 700 potential respondents in Ghana, of which 693 responded, representing 99% of the questionnaires distributed. The Technology Acceptance Model (TAM) was used as the theoretical framework for the study. The Statistical Package for Social Science (SPSS) was used to capture and analyze the data. The results indicate that even though predictors such as PU and PEOU are main determiners of citizens’ intention to adopt and use e-government services in Ghana, it failed to show that PEOU and IU e-government services in Ghana is significantly moderated by the PU of e-government services. The implication of this finding on theory and practice is further discussed.

Keywords: e-government services, intention to use, moderating role, perceived ease of use, perceived usefulness, Ghana, technology acceptance model

Procedia PDF Downloads 413