Search results for: space reconstruction

Authors: Arun Kumar Yadav, Badam Singh Kushvah

Abstract:

In the present work, we investigated displaced periodic orbits in the linear order in the circular restricted three-body Sun-Jupiter system, where the third mass-less body utilizes solar electric sail. The electric solar sail is a new space propulsion concept which uses the solar wind momentum for producing thrust, and it is somewhat like to the more well-known solar radiation pressure sail which is often called simply the solar sail. Moreover, we implement the feedback linearization control scheme to perform the stabilization and trajectory tracking for the nonlinear system. Further, we derived periodic orbits analytically in linear order by introducing a first order approximation. These approximate analytic solutions are utilized in a numerical search to determine displaced periodic orbit in the full nonlinear model. We found the displaced periodic orbit for the defined non-linear model and stabilized the model.

Keywords: solar electric sail, circular restricted three-body problem (CRTBP), displaced orbit, feedback linearization control

Procedia PDF Downloads 189

Authors: Emmanuel Uba, Lily Chimuanya, Maryam Tar

Abstract:

Orthographic engineering is no longer the preserve of the Short Messaging Service (SMS), which is characterised by limited space. Such stylistic creativity or deviation is fast creeping into real-time messaging, popularly known as Instant Messaging (IM), despite the large number of characters allowed. This occurs at various linguistic levels: phonology, morphology, syntax, etc. Nigerians are not immune to this linguistic stylisation. This study investigates the phonological and meta-phonological conventions of the messages sent and received via WhatsApp by Nigerian graduates. This is ontological study of 250 instant messages collected from 98 graduates from different ethnic groups in Nigeria. The selection and analysis of the messages are based on figure and ground principle. The results reveal the use of accent stylisation, phoneme substitution, blending, consonantisation (a specialised form of deletion targeting vowels), numerophony (using a figure/number, usually 1-10, to represent a word or syllable that has the same sound) and phonetic respelling in the IMs sent by Nigerians. The study confirms the existence of linguistic creativity.

Keywords: figure and ground principle, instant messaging, linguistic stylisation, meta-phonology

Procedia PDF Downloads 396

Authors: Badr M. Alshammari, A. Rabeh, A. K. Mohamed

Abstract:

This paper presents the modeling and the control of a grid-connected photovoltaic system (PVS). Firstly, the MPPT control of the PVS and its associated DC/DC converter has been analyzed in order to extract the maximum of available power. Secondly, the control system of the grid side converter (GSC) which is a three-phase voltage source inverter (VSI) has been presented. A special attention has been paid to the control algorithms of the GSC converter during grid voltages imbalances. Especially, three different control objectives are to achieve; the mitigation of the grid imbalance adverse effects, at the point of common coupling (PCC), on the injected currents, the elimination of double frequency oscillations in active power flow, and the elimination of double frequency oscillations in reactive power flow. Simulation results of two control strategies have been performed via MATLAB software in order to demonstrate the particularities of each control strategy according to power quality standards.

Keywords: renewable energies, photovoltaic systems, dc link, voltage source inverter, space vector SVPWM, unbalanced voltage dips, symmetrical components

Procedia PDF Downloads 377

Authors: Abdullah Eqal Al Mazrooei

Abstract:

In this paper, a nonlinear dynamical system is presented. This system is a bilinear class. The bilinear systems are very important kind of nonlinear systems because they have many applications in real life. They are used in biology, chemistry, manufacturing, engineering, and economics where linear models are ineffective or inadequate. They have also been recently used to analyze and forecast weather conditions. Bilinear systems have three advantages: First, they define many problems which have a great applied importance. Second, they give us approximations to nonlinear systems. Thirdly, they have a rich geometric and algebraic structures, which promises to be a fruitful field of research for scientists and applications. The type of nonlinearity that is treated and analyzed consists of bilinear interaction between the states vectors and the system input. By using some properties of the tensor product, these systems can be transformed to linear systems. But, here we discuss the nonlinearity when the state vector is multiplied by itself. So, this model will be able to handle evolutions according to the Lotka-Volterra models or the Lorenz weather models, thus enabling a wider and more flexible application of such models. Here we apply by using an estimator to estimate temperatures. The results prove the efficiency of the proposed system.

Keywords: Lorenz models, nonlinear systems, nonlinear estimator, state-space model

Procedia PDF Downloads 254

Authors: Farid Arya, Trevor Hyde

Abstract:

The development of vacuum glazing represents a significant advancement in the area of low heat loss glazing systems with the potential to substantially reduce building heating and cooling loads. Vacuum glazing consists of two or more glass panes hermetically sealed together around the edge with a vacuum gap between the panes. To avoid the glass panes from collapsing and touching each other under the influence of atmospheric pressure an array of support pillars is provided between the glass panes. A high level of thermal insulation is achieved by evacuating the spaces between the glass panes to a very low pressure which greatly reduces conduction and convection within the space; therefore heat transfer through this kind of glazing is significantly lower when compared with conventional insulating glazing. However, vacuum glazing is subject to inherent stresses due to atmospheric pressure and temperature differentials which can lead to fracture of the glass panes and failure of the edge seal. A flexible edge seal has been proposed to minimise the impact of these issues. In this paper, vacuum glazing system with rigid and flexible edge seals is theoretically studied and their advantages and disadvantages are discussed.

Keywords: flexible edge seal, stress, support pillar, vacuum glazing

Procedia PDF Downloads 234

Authors: Ayoti Banerjee, Meenakshi Banerjee

Abstract:

The study of metamorphic reaction textures is important in contributing to our understanding of the evolution of metamorphic terranes. Where preserved, they provide information on changes in the P-T conditions during the metamorphic history of the rock, and thus allow us to speculate on the P-T-t evolution of the terrane. Mafic dykes have attracted the attention of petrologists because they act as window to mantle. This rock represents a mafic dyke of doleritic composition. It is fine to medium grained in which clinopyroxene are enclosed by the lath shaped plagioclase grains to form spectacular ophitic texture. At places, sub ophitic texture was also observed. Grains of pyroxene and plagioclase show very less deformation typically plagioclase showing deformed lamella along with plagioclase-clinopyroxene-phyric granoblastic fabric within a groundmass of feldspar microphenocrysts and Fe–Ti oxides. Both normal and reverse zoning were noted in the plagioclase laths. The clinopyroxene grains contain exsolved phases such as orthopyroxene, plagioclase, magnetite, ilmenite along the cleavage traces and the orthopyroxene lamella form granules in the periphery of the clinopyroxene grains. Garnet corona also develops preferentially around plagioclase at the contact of clinopyroxene, ilmenite or magnetite. Tiny quartz and K-fs grains showed symplectic intergrowth with garnet at a few places. The product quartz formed along with garnet rims the coronal garnet and the reacting clinopyroxene. Thin amphibole corona formed along the periphery of deformed plagioclase and clinopyroxene occur as patches over the magmatic minerals. The amphibole coronas cannot be assigned to a late magmatic stage and are interpreted as reactive being restricted to the contact between clinopyroxene and plagioclase, thus postdating the crystallization of both. The amphibole and garnet do not share grain boundary in the entire rock and is thus pointing towards simultaneous crystallization. Olivine is absent. Spectacular myrmekitic growth of orthoclase and quartz rimming the plagioclase is consistent with the potash metasomatic effects that is also found in other rocks of this region. These textural features are consistent with a phase of fluid induced metamorphism (retrogression). But the appearance of coronal garnet and amphibole exclusive of each other reflects the participation if Ti as the prime reason. Presence of Ti as a reactant phase is a must for amphibole forming reactions whereas it is not so in case of garnet forming reactions although the reactants are the same plagioclase and clinopyroxene in both cases. These findings are well validated by petrographical and textural analysis. In order to obtain balanced chemical reactions that explain formation of amphibole and garnet in the mafic dyke rocks a matrix operation technique called Singular Value Decomposition (SVD) was adopted utilizing the measured chemical compositions of the minerals. The computer program C-Space was used for this purpose and the required compositional matrix. Data fed to C-Space was after doing cation-calculation of the oxide percentages obtained from EPMA analysis. The Garnet-Clinopyroxene geothermometer yielded a temperature of 650 degrees Celsius. The Garnet-Clinopyroxene-Plagioclase geobarometer and Al-in amphibole yielded roughly 7.5 kbar pressure.

Keywords: corona, dolerite, geothermometer, metasomatism, metamorphic reaction texture, retrogression

Procedia PDF Downloads 278

Authors: Yanpei Zhen

Abstract:

The nonlinear Schrödinger (NLS) equation models wave dynamics in many physical problems related to fluids, plasmas, and optics. The standing periodic waves are known to be modulationally unstable, and rogue waves (localized perturbations in space and time) have been observed on their backgrounds in numerical experiments. The exact solutions for rogue waves arising on the periodic standing waves have been obtained analytically. It is natural to ask if the rogue waves persist on the standing periodic waves in the integrable discretizations of the integrable NLS equation. We study the standing periodic waves in the semidiscrete integrable system modeled by the high-order Ablowitz-Ladik (AL) equation. The standing periodic wave of the high-order AL equation is expressed by the Jacobi cnoidal elliptic function. The exact solutions are obtained by using the separation of variables and one-fold Darboux transformation. Since the cnoidal wave is modulationally unstable, the rogue waves are generated on the periodic background.

Keywords: Darboux transformation, periodic wave, Rogue wave, separating the variables

Procedia PDF Downloads 183

Authors: Bin Su

Abstract:

This study focuses on the impact of school building design factors on winter extra energy consumption which mainly includes space heating, water heating and other appliances related to winter indoor thermal conditions. A number of Auckland schools were randomly selected for the study which introduces a method of using real monthly energy consumption data for a year to calculate winter extra energy data of school buildings. The study seeks to identify the relationships between winter extra energy data related to school building design data related to the main architectural features, building envelope and elements of the sample schools. The relationships can be used to estimate the approximate saving in winter extra energy consumption which would result from a changed design datum for future school development, and identify any major energy-efficient design problems. The relationships are also valuable for developing passive design guides for school energy efficiency.

Keywords: building energy efficiency, building thermal design, building thermal performance, school building design

Procedia PDF Downloads 444

Authors: Jose Alberto Duarte Moller, Cynthia Deisy Gomez Esparza

Abstract:

The cobalt-titanium system was grown as thin films in an INTERCOVAMEX V3 sputtering system, equipped with four magnetrons assisted by DC pulsed and direct DC. A polished highly oriented (400) silicon wafer was used as substrate and the growing temperature was 500 oC. Xray Absorption Spectroscopy experiments were carried out in the SSRL in the 4-3 beam line. The Extenden X-Ray Absorption Fine Structure spectra have been numerically processed by WINXAS software from the background subtraction until the normalization and FFT adjustment. Analyzing the absorption spectra of cobalt in the CoTi2 phase we can appreciate that they agree in energy with the reference spectra that corresponds to the CoO, which indicates that the valence where upon working is Co2+. The RDF experimental results were then compared with those RDF´s generated theoretically by using FEFF software, from a model compound of CoTi2 phase obtained by XRD. The fitting procedure is a highly iterative process. Fits are also checked in R-space using both the real and imaginary parts of Fourier transform. Finally, the presence of overlapping coordination shells and the correctness of the assumption about the nature of the coordinating atom were checked.

Keywords: XAS, EXAFS, FEFF, CoTi

Procedia PDF Downloads 296

Authors: S. Di Benedetto, M. P. Di Donato, A. Rispoli, S. Cardone, J. Riehmer, J. Steelant, L. Vecchione

Abstract:

Thanks to a coordinated funding by the European Space Agency (ESA) and the European Commission (EC) within the 7th framework program, the High-Speed Experimental Fly Vehicles – International (HEXAFLY-INT) project is aimed at the flight validation of hypersonics technologies enabling future trans-atmospheric flights. The project, which is currently involving partners from Europe, Russian Federation and Australia operating under ESA/ESTEC coordination, will achieve the goal of designing, manufacturing, assembling and flight testing an unpowered high speed vehicle in a glider configuration by 2018. The main technical challenges of the project are specifically related to the design of the vehicle gliding configuration and to the complexity of integrating breakthrough technologies with standard aeronautical technologies, e.g. high temperature protection system and airframe cold structures. Also, the sonic boom impact, which is one of the environmental challenges of the high speed flight, will be assessed. This paper provides a comprehensive and detailed update on all the current projects activities carried out to date on both the vehicle and mission design.

Keywords: design, flight testing, HEXAFLY-INT, hypersonics

Procedia PDF Downloads 468

Authors: G. Y. Saspugayeva, R. R. Beysenova, M. R. Khanturin, E. T. Abseitov, K. B. Massenov

Abstract:

This research is devoted to the problems of rocket fuel and impact of its derivatives on environment and living things. Hydrazine derivatives are used in different spheres, in aero-space activity, medical practice, laboratory-diagnosis practice and etc. For Kazakhstan, which has the cosmodrome "Baikonur", the problem of environmental pollution by rocket fuel and its components is important issue. An unsymmetrical dimethylhydrazine is mostly used as rocket fuel for launch vehicles which has high toxicity to humans and animals referred to the World Health Organization. The question about influence of hydrazine derivatives on human organism and ways of detoxication is very actual and requires special approaches in solving these problems. In connection with this situation, we set the goal: study the negative influence of hydrazine derivatives-hydrazine sulphur, nitrosodimethylamine (NDMA), phenylhydrazine, isonicotinic acid hydrazide (IAH) on some biochemical parameters of blood, hepatobiliary system and correction of functional damages of organism with “Salsocollin” drugs.

Keywords: isonicotinic acid hydrazide (IAH), N-nitrosodimethylamine (NDMA), AlAT-alanine aminotransferase, AsAT-aspartate aminotransaminase

Procedia PDF Downloads 355

Authors: M. J. Eichner, Y. S. Sarhan

Abstract:

Overall study purpose has been the evaluation of ‘Vertical Villages’ as a new sustainable building typology, reducing significantly negative impacts of rapid urbanization processes in third world capital cities. Commonly in fast-growing cities, housing and job supply, educational and recreational opportunities, as well as public transportation infrastructure, are not accommodating rapid population growth, exposing people to high noise and emission polluted living environments with low-quality neighborhoods and a lack of recreational areas. Like many others, Egypt’s capital city Cairo, according to the UN facing annual population growth rates of up to 428.000 people, is struggling to address the general deterioration of urban living conditions. New settlements typologies and urban reconstruction approach hardly follow sustainable urbanization principles or socio-ecologic urbanization models with severe effects not only for inhabitants but also for the local environment and global climate. The authors prove that ‘Vertical Village’ buildings can offer a sustainable solution for increasing urban density with at the same time improving the living quality and urban environment significantly. Inserting them within high-density urban fabrics the ecologic and socio-cultural conditions of low-quality neighborhoods can be transformed towards districts, considering all needs of sustainable and social urban life. This study analyzes existing building typologies in Cairo’s «low quality - high density» districts Ard el Lewa, Dokki and Mohandesen according to benchmarks for sustainable residential buildings, identifying major problems and deficits. In 3 case study design projects, the sustainable transformation potential through ‘Vertical Village’ buildings are laid out and comparative studies show the improvement of the urban microclimate, safety, social diversity, sense of community, aesthetics, privacy, efficiency, healthiness and accessibility. The main result of the paper is that the disadvantages of density and overpopulation in developing countries can be converted with ‘Vertical Village’ buildings into advantages, achieving attractive and environmentally friendly living environments with multiple synergies. The paper is documenting based on scientific criteria that mixed-use vertical building structures, designed according to sustainable principles of low rise housing, can serve as an alternative to convert «low quality - high density» districts in megacities, opening a pathway for governments to achieve sustainable urban transformation goals. Neglected informal urban districts, home to millions of the poorer population groups, can be converted into healthier living and working environments.

Keywords: sustainable, architecture, urbanization, urban transformation, vertical village

Procedia PDF Downloads 124

Authors: Marcio Leal, Marta Villamil

Abstract:

Computacional recognition of sign languages aims to allow a greater social and digital inclusion of deaf people through interpretation of their language by computer. This article presents a model of recognition of two of global parameters from sign languages; hand configurations and hand movements. Hand motion is captured through an infrared technology and its joints are built into a virtual three-dimensional space. A Multilayer Perceptron Neural Network (MLP) was used to classify hand configurations and Dynamic Time Warping (DWT) recognizes hand motion. Beyond of the method of sign recognition, we provide a dataset of hand configurations and motion capture built with help of fluent professionals in sign languages. Despite this technology can be used to translate any sign from any signs dictionary, Brazilian Sign Language (Libras) was used as case study. Finally, the model presented in this paper achieved a recognition rate of 80.4%.

Keywords: artificial neural network, computer vision, dynamic time warping, infrared, sign language recognition

Procedia PDF Downloads 217

Authors: Yaowei Hu, Yongkai Wu, Lu Zhang, Xintao Wu

Abstract:

Causal inference from observational data is receiving wide applications in many fields. However, unidentifiable situations, where causal effects cannot be uniquely computed from observational data, pose critical barriers to applying causal inference to complicated real applications. In this paper, we develop a bounding method for estimating the average causal effect (ACE) under unidentifiable situations due to hidden confounders. We propose to parameterize the unknown exogenous random variables and structural equations of a causal model using neural networks and implicit generative models. Then, with an adversarial learning framework, we search the parameter space to explicitly traverse causal models that agree with the given observational distribution and find those that minimize or maximize the ACE to obtain its lower and upper bounds. The proposed method does not make any assumption about the data generating process and the type of the variables. Experiments using both synthetic and real-world datasets show the effectiveness of the method.

Keywords: average causal effect, hidden confounding, bound estimation, generative adversarial learning

Procedia PDF Downloads 191

Authors: Fayssal Amrane, Azeddine Chaiba

Abstract:

In this paper, type-2 fuzzy logic control (T2FLC) and neuro-fuzzy control (NFC) for a doubly fed induction generator (DFIG) based on direct power control (DPC) with a fixed switching frequency is proposed for wind generation application. First, a mathematical model of the doubly-fed induction generator implemented in d-q reference frame is achieved. Then, a DPC algorithm approach for controlling active and reactive power of DFIG via fixed switching frequency is incorporated using PID. The performance of T2FLC and NFC, which is based on the DPC algorithm, are investigated and compared to those obtained from the PID controller. Finally, simulation results demonstrate that the NFC is more robust, superior dynamic performance for wind power generation system applications.

Keywords: doubly fed induction generator (DFIG), direct power control (DPC), neuro-fuzzy control (NFC), maximum power point tracking (MPPT), space vector modulation (SVM), type 2 fuzzy logic control (T2FLC)

Procedia PDF Downloads 419

Authors: Li Minghui, Min Shaorong, Zhang Jun

Abstract:

This paper aims for studying the operational efficiency of surface warship’s motorized evasion to acoustic homing torpedo. It orderly developed trajectory model, self-guide detection model, vessel evasion model, as well as anti-torpedo error model in three-dimensional space to make up for the deficiency of precious researches analyzing two-dimensionally confrontational models. Then, making use of the Monte Carlo method, it carried out the simulation for the confrontation process of evasion in the environment of MATLAB. At last, it quantitatively analyzed the main factors which determine vessel’s survival probability. The results show that evasion relative bearing and speed will affect vessel’s survival probability significantly. Thus, choosing appropriate evasion relative bearing and speed according to alarming range and alarming relative bearing for torpedo, improving alarming range and positioning accuracy and reducing the response time against torpedo will improve the vessel’s survival probability significantly.

Keywords: acoustic homing torpedo, vessel evasion, monte carlo method, torpedo defense, vessel's survival probability

Procedia PDF Downloads 455

Authors: Melissa L Gould

Abstract:

The uptick in social media users during the COVID-19 lockdowns has accelerated concerns about cellphone addiction, cyberbullying, and exposure to harmful content, particularly mis- and disinformation and extremist content. The validity of these concerns is synthesized for media technologists to expose the strategies behind social media and search platform technology and explain why they restrict their children from using it. Banning cell phones in schools, increasing age limits on social media accounts, and putting warning labels on social media are some of the solutions proposed to protect young people from smartphones and social media. Largely missing from these conversations are the voices of young people (rangatahi). Instead, their lived experiences are being told and managed by adults. This presentation will outline my research that amplified the voices and lived experiences of young people by positioning them as experts. Using The Social Dilemma as a discussion prompt, the focus groups of rangatahi in Aotearoa, New Zealand, provide a space for young people to articulate their own lived experiences and respond to the dominant narratives on their generation's use of smartphones and social media.

Keywords: social media, smart phones, young people, social dilemma

Procedia PDF Downloads 31

Authors: Erion Luga, Aksel Seitllari, Kemal Pervanqe

Abstract:

This study investigates the relation between physical and mechanical properties of concrete paving stones using neuro-fuzzy approach. For this purpose 200 samples of concrete paving stones were selected randomly from different sources. The first phase included the determination of physical properties of the samples such as water absorption capacity, porosity and unit weight. After that the indirect tensile strength test and compressive strength test of the samples were performed. İn the second phase, adaptive neuro-fuzzy approach was employed to simulate nonlinear mapping between the above mentioned physical properties and mechanical properties of paving stones. The neuro-fuzzy models uses Sugeno type fuzzy inference system. The models parameters were adapted using hybrid learning algorithm and input space was fuzzyfied by considering grid partitioning. It is concluded based on the observed data and the estimated data through ANFIS models that neuro-fuzzy system exhibits a satisfactory performance.

Keywords: paving stones, physical properties, mechanical properties, ANFIS

Procedia PDF Downloads 342

Authors: Luis Miguel Méndez Díaz

Abstract:

In this article, a mathematics teaching-learning strategy will be presented, specifically differential calculus in one variable, in a fun and competitive space in which the action on the part of the student is manifested and not only the repetition of information on the part of the teacher. Said action refers to motivating, problematizing, summarizing, and coordinating a game of dominoes whose thematic cards are designed around the basic and main contents of differential calculus. The strategies for teaching this area are diverse and precisely the game of dominoes is one of the most used strategies in the practice of mathematics because it stimulates logical reasoning and mental abilities. The objective on this investigation is to identify the way in which the game of dominoes affects the learning and understanding of fundamentals concepts of differential calculus in one variable through experimentation carried out on students of the first semester of the School of Engineering and Sciences of the Technological Institute of Monterrey Campus Querétaro. Finally, the results of this study will be presented and the use of this strategy in other topics around mathematics will be recommended to facilitate logical and meaningful learning in students.

Keywords: collaborative learning, logical-mathematical intelligence, mathematical games, multiple intelligences

Procedia PDF Downloads 84

Authors: Sonia Mannan, M. Jobair Alam

Abstract:

The concept of palliative care in Bangladesh largely remained limited to the sympathetic caring of patients with a life-limiting illness. Quality of Life (QoL) issues are rarely practiced in Bangladesh. Furthermore, palliative medicine, in the perspective of holistic palliative care service, does not have its proper recognition in Bangladesh. Apart from those socio-medical aspects, palliative care patients face legal issues that impact their quality of life, including access to health services and social benefits and dealing with other life-transactions of the patients and their families (such as disposing of property; planning for children). This paper is an attempt to articulate these legal dimensions of the right to palliative care in the context of Bangladesh. The major focus of this paper will be founded on the doctrinal analysis of the constitutional provisions and other relevant legislation on the right to health and their judicial interpretation, which is argued to offer a meaningful space for the right to palliative care. This paper will also investigate the gaps in the said legal framework to better secure such care. In conclusion, a few recommendations are made so that the palliative care practices in Bangladesh are better aligned with international standards, and it can respond more humanely to the patients who need palliative care.

Keywords: Bangladesh, constitution, legal regime, palliative care, quality of life

Procedia PDF Downloads 143

Authors: Jennifer Gallup, Beverly Ray, Esther Ntuli

Abstract:

Many students such as students from linguistically or culturally diverse backgrounds and those with a disability remain chronically underrepresented in higher level science and mathematics disciplines as well as many hands-on-lab-based activities due to the need for remedial reading and mathematics instruction. Makerspace labs can be a conduit for supporting inclusive learning for these students through hands-on active learning strategies that support equitable access to STEM disciplines. Makerspace is a physical space where individuals gather to create, invent, innovate, and learn while using hands-on materials such as 2D and 3D printers, software programs, electronics, and other tools and supplies. Makerspaces are emerging across many P-12 settings; however, many teachers enter the field not prepared to harness the power inherent in a makerspace, especially for those with disabilities and differing needs. This paper offers suggestions on teaching pre-service teachers and practicing teachers how to incorporate a makerspace into their professional practice through guided instruction and hands-on practice. Recommendations for interested stakeholders are included as well.

Keywords: STEM learning, technology, autism, students with disabilities, makerspace

Procedia PDF Downloads 95

Authors: Khalid Al-Snaie

Abstract:

In this paper, the design and the testing of a symmetrical radiofrequency prototype coil with high B₁ magnetic field homogeneity are presented. The developed coil comprises four tuned coaxial circular loops that can produce a relatively homogeneous radiofrequency field. In comparison with a standard Helmholtz pair that provides 2nd-order homogeneity, it aims to provide fourth-order homogeneity of the B₁ field while preserving the simplicity of implementation. Electrical modeling of the probe, including all couplings, is used to ensure these requirements. Results of comparison tests, in free space and in a spectro-imager, between a standard Helmholtz pair and the presented prototype coil are introduced. In terms of field homogeneity, an improvement of 30% is observed. Moreover, the proposed prototype coil possesses a better quality factor (+25% on average) and a noticeable improvement in sensitivity (+20%). Overall, this work, which includes both theoretical and experimental aspects, aims to contribute to the study and understanding of four-element radio frequency (RF) systems derived from Helmholtz coils for Magnetic Resonance Imaging

Keywords: B₁ homogeneity, MRI, NMR, radiofrequency, RF coil, free element systems

Procedia PDF Downloads 90

Authors: Farooq A. Al-Sheikh, Ali Elkamel, William A. Anderson

Abstract:

A fluidized catalytic cracking unit (FCCU) is one of the effective units in many refineries. Modeling and optimization of FCCU were done by many researchers in past decades, but in this research, comparison between post- and oxy-combustion was studied in the regenerator-FCCU. Therefore, a simplified mathematical model was derived by doing mass/heat balances around both reactor and regenerator. A state space analysis was employed to show effects of the flow rates variables such as air, feed, spent catalyst, regenerated catalyst and flue gas on the output variables. The main aim of studying dynamic responses is to figure out the most influencing variables that affect both reactor/regenerator temperatures; also, finding the upper/lower limits of the influencing variables to ensure that temperatures of the reactors and regenerator work within normal operating conditions. Therefore, those values will be used as side constraints in the optimization technique to find appropriate operating regimes. The objective functions were modeled to be maximizing the energy in the reactor while minimizing the energy consumption in the regenerator. In conclusion, an oxy-combustion process can be used instead of a post-combustion one.

Keywords: FCCU modeling, optimization, oxy-combustion, post-combustion

Procedia PDF Downloads 211

Authors: Mengesha Mamo Wogari

Abstract:

In this paper, low voltage multiphase brushless DC motor with square wave air-gap flux distribution for electric vehicle application is proposed. Ten-phase, 5 kW motor, has been designed and simulated by finite element methods demonstrating the desired high torque capability at low speed and flux weakening operation for high-speed operations. The motor torque is proportional to number of phases for a constant phase current and air-gap flux. The concept of vector control and simple space vector modulation technique is used on MATLAB to control the motor demonstrating simple switching pattern for selected number of phases. The low voltage DC and inverter output AC are desired characteristics to avoid any electric shock in the vehicle, accidentally and during abnormal conditions. The switching devices for inverter are of low-voltage rating and cost effective though their number is equal to twice the number of phases.

Keywords: brushless DC motors, electric Vehicle, finite element methods, Low-voltage inverter, multiphase

Procedia PDF Downloads 154

Authors: Ludivine Saint-Mard, Masato Nakajima, Gloria Senfaute

Abstract:

In areas with low to moderate seismicity, the probabilistic seismic hazard analysis frequently uses a Poisson approach, which assumes independence in time and space of events to determine the annual probability of earthquake occurrence. Nevertheless, in countries with high seismic rate, such as Japan, it is frequently use non-poissonian model which assumes that next earthquake occurrence depends on the date of previous one. The objective of this paper is to apply a non-poissonian models in a region of low to moderate seismicity to get a feedback on the following questions: can we overcome the lack of data to determine some key parameters?, and can we deal with uncertainties to apply largely this methodology on an industrial context?. The Brownian-Passage-Time model was applied to a fault located in France and conclude that even if the lack of data can be overcome with some calculations, the amount of uncertainties and number of scenarios leads to a numerous branches in PSHA, making this method difficult to apply on a large scale of low to moderate seismicity areas and in an industrial context.

Keywords: probabilistic seismic hazard, non-poissonian model, earthquake occurrence, low seismicity

Procedia PDF Downloads 62

Authors: Nada Slimane, Foued Theljani, Faouzi Bouani

Abstract:

The paper addresses the problem of fault diagnosis for systems operating in several modes (normal or faulty) based on states assessment. We use, for this purpose, a methodology consisting of three main processes: 1) sequential data clustering, 2) linear model regression and 3) state filtering. Typically, Kalman Filter (KF) is an algorithm that provides estimation of unknown states using a sequence of I/O measurements. Inevitably, although it is an efficient technique for state estimation, it presents two main weaknesses. First, it merely predicts states without being able to isolate/classify them according to their different operating modes, whether normal or faulty modes. To deal with this dilemma, the KF is endowed with an extra clustering step based fully on sequential version of the k-means algorithm. Second, to provide state estimation, KF requires state space models, which can be unknown. A linear regularized regression is used to identify the required models. To prove its effectiveness, the proposed approach is assessed on a simulated benchmark.

Keywords: clustering, diagnosis, Kalman Filtering, k-means, regularized regression

Procedia PDF Downloads 182

Authors: Payal Patel

Abstract:

Textile machinery is one of the fastest evolving areas which has an application of mechanical engineering. The modular approach towards the processing right from the stage of cotton to the fabric, allows us to observe the result of each process on its input. Cost and space being the major constraints. The flyer is a component of roving machine, which is used as a part of spinning process. In the present work using the application of Hyper Works, the flyer arm has been modified which saves the material used for manufacturing the flyer. The size optimization of the flyer is carried out with the objective of reduction in weight under the constraints of standard operating conditions. The new design of the flyer is proposed and validated using the module of HyperWorks which is equally strong, but light weighted compared to the existing design. Dynamic balancing of the optimized model is carried out to align a principal inertia axis with the geometric axis of rotation. For the balanced geometry of flyer, air resistance is obtained theoretically and with Gambit and Fluent. Static analysis of the balanced geometry has been done to verify the constraint of operating condition. Comparison of weight, deflection, and factor of safety has been made for different aluminum alloys.

Keywords: flyer, size optimization, textile, weight

Procedia PDF Downloads 215

Authors: Baghdad Said

Abstract:

Differential equations of fractional order have proved to be important tools to describe many physical phenomena and have been used in diverse fields such as engineering, mathematics as well as other applied sciences. On the other hand, the theory of differential equations involving the Stieltjes derivative (SD) with respect to a non-decreasing function is a new class of differential equations and has many applications as a unified framework for dynamic equations on time scales and differential equations with impulses at fixed times. The aim of this paper is to investigate the existence, uniqueness, and generalized Ulam-Hyers-Rassias stability (UHRS) of solutions for a boundary value problem of sequential fractional differential equations (SFDE) containing (SD). This study is based on the technique of noncompactness measures (MNCs) combined with Monch-Krasnoselski fixed point theorems (FPT), and the results are proven in an appropriate Banach space under sufficient hypotheses. We also give an illustrative example. In this work, we introduced a class of (SFDE) and the results are obtained under a few hypotheses. Future directions connected to this work could focus on another problem with different types of fractional integrals and derivatives, and the (SD) will be assumed under a more general hypothesis in more general functional spaces.

Keywords: SFDE, SD, UHRS, MNCs, FPT

Procedia PDF Downloads 40

Authors: Ahmed A. Al-Harbi

Abstract:

This paper presents a comparative study of effects of the repeated solid obstacles on the propagation of H2-Air premixed flames. Pressure, speed of the flame front as well as structure of reaction zones are studied for hydrogen. Two equivalence ratios are examined for different configurations of three baffle plates and two obstacles with a square cross-section having blockage ratios of either 0.24 or 0.5. Hydrogen fuel mixtures with two equivalence ratios of 0.7 and 0.8 are studied and this is limited by the excessive overpressures. The results show that the peak pressure and its rate of change can be increased by increasing the blockage ratio or by decreasing the space between successive baffles. As illustrated by the high speed images of LIF-OH, the degree of wrinkling and contortion in the flame front increase as the blockages increase. The images also show how the flame front relaminarises with increasing distances between obstacles, which accounts for the pressure decrease with increasing separation. It is also found that more than one obstacle is needed to achieve a turbulent flame structure with intense corrugations.

Keywords: premixed propagating flames, flame-obstacle interaction, turbulent premixed flames, overpressure, transient flames

Procedia PDF Downloads 377

Authors: Umar Albalawi, Sang C. Suh, Jinoh Kim

Abstract:

As internet continues to expand its usage with an enormous number of applications, cyber-threats have significantly increased accordingly. Thus, accurate detection of malicious traffic in a timely manner is a critical concern in today’s Internet for security. One approach for intrusion detection is to use Machine Learning (ML) techniques. Several methods based on ML algorithms have been introduced over the past years, but they are largely limited in terms of detection accuracy and/or time and space complexity to run. In this work, we present a novel method for intrusion detection that incorporates a set of supervised learning algorithms. The proposed technique provides high accuracy and outperforms existing techniques that simply utilizes a single learning method. In addition, our technique relies on partial flow information (rather than full information) for detection, and thus, it is light-weight and desirable for online operations with the property of early identification. With the mid-Atlantic CCDC intrusion dataset publicly available, we show that our proposed technique yields a high degree of detection rate over 99% with a very low false alarm rate (0.4%).

Keywords: intrusion detection, supervised learning, traffic classification, computer networks

Procedia PDF Downloads 350