Search results for: finite difference

Authors: Nitin Ghule, S. G. Taji

Abstract:

A mathematical model of hot-wall condensers used in refrigerators is presented. The model predicts the heat transfer characteristics of condenser and the effects of various design and operating parameters on condenser tube length and capacity. A finite element approach was used to model the condenser. The condenser tube is divided into elemental units, with each element consisting of adhesive tape, refrigerant tube and outer metal sheet. The heat transfer characteristics of each section are then analyzed by considering the heat transfer through the tube wall, tape and the outer sheet. Variations in inner heat transfer coefficient and pressure drop are considered depending on temperature, fluid phase, type of flow and orientation of tube. Variation in outer heat transfer coefficient is also taken into account. Various materials were analysed for the tube, tape and outer sheet.

Keywords: condenser, domestic refrigerator, heat transfer, mathematical model

Procedia PDF Downloads 452

Authors: Mounir Gaci, Salim Meziani, Atmane Fouathia

Abstract:

The purpose of the present paper is to model the behavior of metal alloy, type TRIP steel (Transformation Induced Plasticity), during solid/solid phase transition. A two-dimensional micromechanical model is implemented in finite element software (ZEBULON) to simulate the martensitic transformation in Fe-Ni-C steel grain under mechanical tensile stress of 250 MPa. The effects of non-uniform grain boundary and the criterion of mechanical shear load on the transformation and on the TRIP value during martensitic transformation are studied. The suggested mechanical criterion is favourable to the influence of the shear phenomenon on the progression of the martensitic transformation (Magee’s mechanism). The obtained results are in satisfactory agreement with experimental ones and show the influence of the grain boundary shape and the chosen mechanical criterion (SMF) on the transformation parameters.

Keywords: martensitic transformation, non-uniform Grain Boundary, TRIP, shear Mechanical force (SMF)

Procedia PDF Downloads 261

Authors: Evgeny N. Zakharin, Bartosz Majewski

Abstract:

Foaming polyurethane is a ground improvement technology that is increasingly used for foundation stabilization with differential settlement and controlled foundation structure lifting. This technology differs from conventional mineral grout due to its injection composition, which provides high-pressure expansion quickly due to a chemical reaction. The technology has proven efficient in the typical geological conditions of the United Arab Emirates. An in-situ trial foundation load test has been proposed to objectively assess the deformative and load-bearing characteristics of the soil after injection. The article provides a detailed description of the experiment carried out in field conditions. Based on the practical experiment's results and its finite element modeling, the deformation modulus of the soil after treatment was determined, which was more than five times higher than the initial value.

Keywords: chemical grout, expanding polyurethane resin, foundation remediation, ground improvement

Procedia PDF Downloads 59

Authors: Brando Vagenende, Marie-Anne Guerry

Abstract:

For stochastic matrices of any order, the geometric description of the convex set of eigenvalues is completely known. The purpose of this study is to investigate the subset of the monotone matrices. This type of matrix appears in contexts such as intergenerational occupational mobility, equal-input modeling, and credit ratings-based systems. Monotone matrices are stochastic matrices in which each row stochastically dominates the previous row. The monotonicity property of a stochastic matrix can be expressed by a nonnegative lower-order matrix with the same eigenvalues as the original monotone matrix (except for the eigenvalue 1). Specifically, the aim of this research is to focus on the properties of eigenvalues of monotone matrices. For those matrices up to order 3, there already exists a complete description of the convex set of eigenvalues. For monotone matrices of order at least 4, this study gives, through simulations, more insight into the geometric description of their eigenvalues. Furthermore, this research treats in a geometric and algebraic way the properties of eigenvalues of monotone matrices of order at least 4.

Keywords: eigenvalues of matrices, finite Markov chains, monotone matrices, nonnegative matrices, stochastic matrices

Procedia PDF Downloads 80

Authors: Alexander Pesin, Denis Pustovoytov, Mikhail Sverdlik

Abstract:

Materials with ultrafine-grained structure and unique physical and mechanical properties can be obtained by methods of severe plastic deformation, which include processes of asymmetric rolling (AR). Asymmetric rolling is a very effective way to create ultrafine-grained structures of metals and alloys. Since the asymmetric rolling is a continuous process, it has great potential for industrial production of ultrafine-grained structure sheets. Basic principles of asymmetric rolling are described in detail in scientific literature. In this work finite element modeling of asymmetric rolling and metal forming processes in multiroll gauge was performed. Parameters of the processes which allow achieving significant values of shear strain were defined. The results of the study will be useful for the research of the evolution of ultra-fine metal structure in asymmetric rolling.

Keywords: asymmetric rolling, equivalent strain, FEM, multiroll gauge, profile, severe plastic deformation, shear strain, sheet

Procedia PDF Downloads 265

Authors: Jyoti Jha, Asim Tewari, Sushil Mishra

Abstract:

The alpha-beta Titanium alloy (Ti-6Al-4V) is the most common alloy in the aerospace industry. The hot workability of Ti–6Al–4V has been investigated by means of hot compression tests carried out in the 750–950 °C temperature range and 0.001–10s-1 strain rate range. Stress-strain plot obtained from the Gleeble 3800 test results show the dynamic recrystallization at temperature 950 °C. The effect of microstructural characteristics of the deformed specimens have been studied and correlated with the test temperature, total strain and strain rate. Finite element analysis in DEFORM 2D has been carried out to see the effect of flow stress parameters in different zones of deformed sample. Dynamic recrystallization simulation based on Cellular automata has been done in DEFORM 2D to simulate the effect of hardening and recovery during DRX. Simulated results well predict the grain growth and DRX in the deformed sample.

Keywords: compression test, Cellular automata, DEFORM , DRX

Procedia PDF Downloads 301

Authors: Robert Long

Abstract:

The results of a one-year study on the evolution of complexity, accuracy, and fluency (CAF) in the compositions of Japanese L2 university students throughout a semester are presented in this study. One goal was to determine if any improvement in writing abilities over this academic term had occurred, while another was to examine methods of editing. Participants had 30 minutes to write each essay with an additional 10 minutes allotted for editing. As for editing, participants were divided into two groups, one of which utilized an online grammar checker, while the other half self-edited their initial manuscripts. From the three different institutions, there was a total of 159 students. Research questions focused on determining if the CAF had evolved over the previous year, identifying potential variations in editing techniques, and describing the connections between the CAF dimensions. According to the findings, there was some improvement in accuracy (fewer errors) in all three of the measures), whereas there was a marked decline in complexity and fluency. As for the second research aim relating to the interaction among the three dimensions (CAF) and of possible increases in fluency being offset by decreases in grammatical accuracy, results showed (there is a logical high correlation with clauses and word counts, and mean length of T-unit (MLT) and (coordinate phrase of T-unit (CP/T) as well as MLT and clause per T-unit (C/T); furthermore, word counts and error/100 ratio correlated highly with error-free clause totals (EFCT). Issues of syntactical complexity had a negative correlation with EFCT, indicating that more syntactical complexity relates to decreased accuracy. Concerning a difference in error correction between those who self-edited and those who used an online grammar correction tool, results indicated that the variable of errors-free clause ratios (EFCR) had the greatest difference regarding accuracy, with fewer errors noted with writers using an online grammar checker. As for possible differences between the first and second (edited) drafts regarding CAF, results indicated there were positive changes in accuracy, the most significant change seen in complexity (CP/T and MLT), while there were relatively insignificant changes in fluency. Results also indicated significant differences among the three institutions, with Fujian University of Technology having the most fluency and accuracy. These findings suggest that to raise students' awareness of their overall writing development, teachers should support them in developing more complex syntactic structures, improving their fluency, and making more effective use of online grammar checkers.

Keywords: complexity, accuracy, fluency, writing

Procedia PDF Downloads 41

Authors: Athmane Bakhta, Sebastien Leclaire, David Vidal, Francois Bertrand, Mohamed Cheriet

Abstract:

This work presents a new three-dimensional variational model proposed for the simulation of ink seepage into paper sheets at the fiber level. The model, inspired by the Hising model, takes into account a finite volume of ink and describes the system state through gravity, cohesion, and adhesion force interactions. At the mesoscopic scale, the paper substrate is modeled using a discretized fiber structure generated using a numerical deposition procedure. A modified Monte Carlo method is introduced for the simulation of the ink dynamics. Besides, a multiphase lattice Boltzmann method is suggested to fine-tune the mesoscopic variational model parameters, and it is shown that the ink seepage behaviors predicted by the proposed model can resemble those predicted by a method relying on first principles.

Keywords: fibrous media, lattice Boltzmann, modelling and simulation, Monte Carlo, variational model

Procedia PDF Downloads 147

Authors: Oke Oktavianty, Tadayuki Kyoutani, Shigeyuki Haruyama, Junji Kaneko, Ken Kaminishi

Abstract:

Modelica has many advantages and it is very useful in modeling and simulation especially for the multi-domain with a complex technical system. However, the big obstacle for a beginner is to understand the basic concept and to build a new system model for a real system. In order to understand how to solve the simple circuit model by hand translation and to get a better understanding of how modelica works, we provide a detailed explanation about solver ordering system in horizontal and vertical sorting and make some proposals for improvement. In this study, some difficulties in using modelica software with the original concept and the comparison with Finite Element Method (FEM) approach is discussed. We also present our textual modeling approach using FEM concept for acausal and causal model construction. Furthermore, simulation results are provided that demonstrate the comparison between using textual modeling with original coding in modelica and FEM concept.

Keywords: FEM, a causal model, modelica, horizontal and vertical sorting

Procedia PDF Downloads 308

Authors: S. Koppikar, P. Kulkarni, D. Ingale , N. Wagh, S. Deshpande, A. Mahajan, A. Harsulkar

Abstract:

Crucial role of reactive oxygen species (ROS) in the progression Osteoarthritis (OA) pathogenesis has been endorsed several times though its exact mechanism remains unclear. Oxidative stress is known to instigate classical stress factors such as cytokines, chemokines and ROS, which hampers cartilage remodelling process and ultimately results in worsening the disease. Synovial fluid (SF) is a biological communicator between cartilage and synovium that accumulates redox and biochemical signalling mediators. The present work attempts to measure several oxidative stress markers in the synovial fluid obtained from knee OA patients with varying degree of disease severity. Thirty OA and five Meniscal-tear (MT) patients were graded using Kellgren-Lawrence scale and assessed for Nitric oxide (NO), Nitrate-Nitrite (NN), 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Antioxidant Potential (FRAP), Catalase (CAT), Superoxide dismutase (SOD) and Malondialdehyde (MDA) levels for comparison. Out of various oxidative markers studied, NO and SOD showed significant difference between moderate and severe OA (p= 0.007 and p= 0.08, respectively), whereas CAT demonstrated significant difference between MT and mild group (p= 0.07). Interestingly, NN revealed statistically positive correlation with OA severity (p= 0.001 and p= 0.003). MDA, a lipid peroxidation by-product was estimated maximum in early OA when compared to MT (p= 0.06). However, FRAP did not show any correlation with OA severity or MT control. NO is an essential bio-regulatory molecule essential for several physiological processes, and inflammatory conditions. However, due to its short life, exact estimation of NO becomes difficult. NO and its measurable stable products are still it is considered as one of the important biomarker of oxidative damage. Levels of NO and nitrite-nitrate in SF of patients with OA indicated its involvement in the disease progression. When SF groups were compared, a significant correlation among moderate, mild and MT groups was established. To summarize, present data illustrated higher levels of NO, SOD, CAT, DPPH and MDA in early OA in comparison with MT, as a control group. NN had emerged as a prognostic bio marker in knee OA patients, which may act as futuristic targets in OA treatment.

Keywords: antioxidant, knee osteoarthritis, oxidative stress, synovial fluid

Procedia PDF Downloads 477

Authors: Chairul Fajar, Muhammad Nur Hidayat, Muksalmina

Abstract:

The issue of Over Dimension Over Loading (ODOL) in Indonesia remains a significant challenge, causing traffic accidents, disrupting traffic flow, accelerating road damage, and potentially leading to bridge collapses. Klaten Regency, located on the slopes of Mount Merapi along the Woro River in Kemalang District, has potential Class C excavation materials such as sand and stone. Data from the Klaten Regency Transportation Department indicates that ODOL violations account for 72%, while non-violating vehicles make up only 28%. ODOL involves modifying factory-standard vehicles beyond the limits specified in the Type Test Registration Certificate (SRUT) to save costs and travel time. This study aims to develop a prototype ‘Sabrang’ monitoring system based on Arduino Mega to control and monitor ODOL freight transportation in the mining of Class C excavation materials in Klaten Regency. The prototype is designed to automatically measure the dimensions and weight of objects using a microcontroller. The data analysis techniques used in this study include the Normality Test and Paired T-Test, comparing sensor measurement results on scaled objects. The study results indicate differences in measurement validation under room temperature and ambient temperature conditions. Measurements at room temperature showed that the majority of H0 was accepted, meaning there was no significant difference in measurements when the prototype tool was used. Conversely, measurements at ambient temperature showed that the majority of H0 was rejected, indicating a significant difference in measurements when the prototype tool was used. In conclusion, the ‘Sabrang’ monitoring system prototype is effective for controlling ODOL, although measurement results are influenced by temperature conditions. This study is expected to assist in the monitoring and control of ODOL, thereby enhancing traffic safety and road infrastructure.

Keywords: over dimension over loading, prototype, microcontroller, Arduino, normality test, paired t-test

Procedia PDF Downloads 35

Authors: Pouya Kaafi, Gholamreza Ghodrati Amiri

Abstract:

Abnormal loads due to natural events, implementation errors and some other issues can lead to occurrence of progressive collapse in structures. Most of the past researches consist of 2- Dimensional (2D) models of steel frames without consideration of the floor system effects, which reduces the accuracy of the modeling. While employing a 3-Dimensional (3D) model and modeling the concrete slab system for the floors have a crucial role in the progressive collapse evaluation. In this research, a 3D finite element model of a 5-story steel building is modeled by the ABAQUS software once with modeling the slabs, and the next time without considering them. Then, the progressive collapse potential is evaluated. The results of the analyses indicate that the lack of the consideration of the slabs during the analyses, can lead to inaccuracy in assessing the progressive failure potential of the structure.

Keywords: abnormal loads, composite floor system, intermediate steel moment resisting frame system, progressive collapse

Procedia PDF Downloads 456

Authors: Jehnming Lin

Abstract:

In the laser cleavage of glass, the laser is mostly adopted as a heat source to generate a thermal stress state on the substrates. The crack propagation of the soda-lime glass in the laser thermal cleavage with the straight-turning paths was investigated in this study experimentally and numerically. The crack propagation was visualized by a high speed camera with the off-line examination on the micro-crack propagation. The temperature and stress distributions induced by the laser heat source were calculated by ANSYS software based on the finite element method (FEM). With the cutting paths in various turning directions, the experimental and numerical results were in comparison and verified. The fracture modes due to the normal and shear stresses were verified at the turning point of the laser cleavage path. It shows a significant variation of the stress profiles along the straight-turning paths and causes a change on the fracture modes.

Keywords: laser cleavage, glass, fracture, stress analysis

Procedia PDF Downloads 230

Authors: Afef Dridi, Salah Mezlini

Abstract:

Since experimental devices cannot calculate stress and deformation of complex structures. The Finite Element Method FEM has been widely used in several fields of research. One of these fields is orthodontics. The advantage of using such a method is the use of an accurate and non invasive method that allows us to have a sufficient data about the physiological reactions can happening in soft tissues. Most of researches done in this field were interested in the study of stresses and deformations induced by orthodontic apparatus in soft tissues (alveolar tissues). Only few studies were interested in the distribution of stress and strain in the orthodontic brackets. These studies, although they tried to be as close as possible to real conditions, their models did not reproduce the clinical cases. For this reason, the model generated by our research is the closest one to reality. In this study, a numerical model was developed to explore the stress and strain distribution under the application of real conditions. A comparison between different material properties was also done.

Keywords: visco-hyperelasticity, FEM, orthodontic treatment, inverse method

Procedia PDF Downloads 259

Authors: Yifan Fan, Xudong Luo, Pingping Lin

Abstract:

An essential task in the field of artificial intelligence is to allow computers to interact with people through natural language. Therefore, researches such as virtual assistants and dialogue systems have received widespread attention from industry and academia. The response generation plays a crucial role in dialogue systems, so to push forward the research on this topic, this paper surveys various methods for response generation. We sort out these methods into three categories. First one includes finite state machine methods, framework methods, and instance methods. The second contains full-text indexing methods, ontology methods, vast knowledge base method, and some other methods. The third covers retrieval methods and generative methods. We also discuss some hybrid methods based knowledge and deep learning. We compare their disadvantages and advantages and point out in which ways these studies can be improved further. Our discussion covers some studies published in leading conferences such as IJCAI and AAAI in recent years.

Keywords: deep learning, generative, knowledge, response generation, retrieval

Procedia PDF Downloads 134

Authors: Diriba Gemechu, Lamessa Abebe

Abstract:

The aim of this study was to examine the effect of cooperative learning method on student’s academic achievement and on the achievement level over a usual method in teaching different topics of mathematics. The study also examines the perceptions of students towards cooperative learning. Cooperative learning is the instructional strategy in which pairs or small groups of students with different levels of ability work together to accomplish a shared goal. The aim of this cooperation is for students to maximize their own and each other learning, with members striving for joint benefit. The teacher’s role changes from wise on the wise to guide on the side. Cooperative learning due to its influential aspects is the most prevalent teaching-learning technique in the modern world. Therefore the study was conducted in order to examine the effect of cooperative learning on the academic achievement of grade 9 students in Mathematics in case of Mettu secondary school. Two sample sections are randomly selected by which one section served randomly as an experimental and the other as a comparison group. Data gathering instruments are achievement tests and questionnaires. A treatment of STAD method of cooperative learning was provided to the experimental group while the usual method is used in the comparison group. The experiment lasted for one semester. To determine the effect of cooperative learning on the student’s academic achievement, the significance of difference between the scores of groups at 0.05 levels was tested by applying t test. The effect size was calculated to see the strength of the treatment. The student’s perceptions about the method were tested by percentiles of the questionnaires. During data analysis, each group was divided into high and low achievers on basis of their previous Mathematics result. Data analysis revealed that both the experimental and comparison groups were almost equal in Mathematics at the beginning of the experiment. The experimental group out scored significantly than comparison group on posttest. Additionally, the comparison of mean posttest scores of high achievers indicates significant difference between the two groups. The same is true for low achiever students of both groups on posttest. Hence, the result of the study indicates the effectiveness of the method for Mathematics topics as compared to usual method of teaching.

Keywords: academic achievement, comparison group, cooperative learning, experimental group

Procedia PDF Downloads 246

Authors: Y. Hu, X. Zhao, T. Yamaguchi, M. Sasajima, Y. Koike

Abstract:

To focus on the vibration mode of a cone loudspeaker, which acts as an electroacoustic transducer, excitation experiments were performed using two types of loudspeaker units: one employing an impulse hammer and the other a sweep signal. The on-axis sound pressure frequency properties of the loudspeaker were evaluated, and the characteristic properties of the loudspeakers were successfully determined in both excitation experiments. Moreover, under conditions identical to the experiment conditions, a coupled analysis of the vibration-acoustics of the cone loudspeaker was performed using an acoustic analysis software program that considers the impact of damping caused by air viscosity. The result of sound pressure frequency properties with the numerical analysis are the most closely match that measured in the excitation experiments over a wide range of frequency bands.

Keywords: anechoic room, finite element method, impulse hammer, loudspeaker, reverberation room, sweep signal

Procedia PDF Downloads 436

Authors: Daniel Y. Abebe, Sijeong Jeong, Jaehyouk Choi

Abstract:

The use of eccentrically braced frame (EBF) is increasing day by day as EBF possesses high elastic stiffness, stable inelastic response under cyclic lateral loading, and excellent ductility and energy dissipation capacity. The ductility and energy dissipation capacity of EBF depends on the active link beams. Recently, there are two types EBFs; these are conventional EBFs and EBFs with replaceable links. The conventional EBF has a disadvantage during maintenance in post-earthquake. The concept of removable active link beam in EBF is developed to overcome the limitation of the conventional EBF in post-earthquake. In this study, a replaceable link with reduced web section is introduced and design equations are suggested. In addition, nonlinear finite element analysis was conducted in order to evaluate the proposed links.

Keywords: EBFs, replaceable link, earthquake disaster, reduced section

Procedia PDF Downloads 334

Authors: Siwimol Phoomniyom, Pathom Karaipoom, Rossaphorn Kittyaowaman

Abstract:

Background: C. trachomatis is the most common bacterial sexually transmitted infections. Although infection with C. trachomatis can be treated with antibiotic, it is frequently asymptomatic, especially in extragenital sites. Hence, if screening tests are not performed, undetected and untreated is a crucial problem for C. trachomatis infection, especially in Thailand, which is less well studied. We sought to assess the prevalence of C. trachomatis infection in multiple anatomical sites among patients attending Bangrak STIs Center. Methods: We examined laboratory results of all patients at baseline visit from 3 January 2018 to 27 December 2019. These results were tested by a validated in-house real time PCR specify for the cryptic plasmid gene of C. trachomatis. The prevalence of C. trachomatis was analyzed by anatomical sites, sexes, and ages. Urogenital samples were obtained from urethral swab of men and cervical swab of women. The median ages of the patients were 32 years (range 13-89 years). Chi-square test by IBM SPSS statistic version 20 was used to assess difference in the distribution of variables between groups. Results: Among 3,789 patients, the prevalence for C. trachomatis infection was the highest in rectal (16.1%), followed by urogenital (11.2%) and pharyngeal (3.5%) sites. Rectal and urogenital infection in men was higher than in women, with the highest prevalence of 16.6% in rectal site. Both rectal and urogenital sites also showed statistically significant differences between sexes (P<0.001). Meanwhile, pharyngeal C. trachomatis infection rate was higher in women than men. Interestingly, the chlamydia prevalence was the highest in age 13-19 years of all three sites (18.5%, urogenital; 17.7%, rectal; 6.5%, pharyngeal), with statistically significant difference between age groups (P<0.001). Total of 45 C. trachomatis infections, 20.0%, 51.1%, and 6.7% were isolated from urogenital, rectal, and pharyngeal sites. In total, 75.6%, 26.7%, and 80.0% of chlamydia infections would have been missed, if only urogenital, rectal, or pharyngeal screening was performed. Conclusions: The highest source of C. trachomatis infection was the rectal site. While, the highest prevalence in men was at rectal site, that in women was at urogenital site. The highest chlamydia prevalence was found in adolescent age group, indicating that the pediatric population was a high-risk group. This finding also elucidated that a high proportion of C. trachomatis infection would be missed, if only single anatomical site screening was performed, especially in extragenital sites. Hence, extragenital screening is also required for the extensive C. trachomatis detection.

Keywords: chlamydia trachomatis, anatomical sites, sexes, ages

Procedia PDF Downloads 70

Authors: Herlina Abdul Rahim, Javad Abbaszadeh, Ruzairi Abdul Rahim

Abstract:

In this research, the non-invasive ultrasonic transmission tomography is investigated. In order to model the ultrasonic wave scattering for different thickness of metal pipes, two-dimensional (2D) finite element modeling (FEM) has been utilized. The wall thickness variation of the metal pipe and its influence on propagation of the ultrasonic pressure wave are explored in this paper, includes frequency analysing in order to find the maximum applicable frequency. The simulation results have been compared to experimental data and are shown to provide key insight for this well-defined experimental case by explaining the achieved reconstructed images from experimental setup. Finally, the experimental results which are useful for further investigation for the application of ultrasonic transmission tomography in industry are illustrated.

Keywords: ultrasonic transmission tomography, ultrasonic sensors, ultrasonic wave, non-invasive tomography, metal pipe

Procedia PDF Downloads 359

Authors: Mohammad Moeini, Mehrdad Ghyabi, Kiarash Mohtasham Dolatshahi

Abstract:

This paper investigates seismic soil-pile interaction using the Beam on Nonlinear Winkler Foundation (BNWF) approach. Three soil types are considered to cover all the possible responses, as well as nonlinear site response analysis using finite element method in OpenSees platform. Excitations at each elevation that are output of the site response analysis are used as the input excitation to the soil pile system implementing multi-support excitation method. Spectral intensities of acceleration show that the extent of the response in sand is more severe than that of clay, in addition, increasing the PGA of ground strong motion will affect the sandy soil more, in comparison with clayey medium, which is an indicator of the sensitivity of soil-pile systems in sandy soil.

Keywords: BNWF method, multi-support excitation, nonlinear site response analysis, seismic soil-pile interaction

Procedia PDF Downloads 394

Authors: Hyun-Woo Jun, In-Gun Kim, Hyun Seok Hong, Dong-Woo Kang, Ju Lee

Abstract:

In high-speed SPMSM design, the rotor-retaining sleeve is inserted into rotor to prevent permanent magnet’s damage. It is quite efficient way considering manufacturability, but the sleeve becomes major source of ohm loss in high-speed operation. In this paper, the high-speed motor for turbo-blower at the rating of 100kW was introduced. To improve its efficiency, the retaining sleeve’s optimal design was needed. Within the range of satisfies the mechanical safety, sleeve’s some design variables have been changed. The effect of changing design variables of the sleeve was studied. This paper presents the optimized sleeve’s advantages in electrical efficiency from the result of electromagnetic FEA (finite element analysis) software. Finally, it suggests the optimal sleeve design to reduce eddy current loss, which is related to motor shape.

Keywords: SPMSM, sleeve, eddy current, high efficiency

Procedia PDF Downloads 424

Authors: Fana Woldetsadik

Abstract:

Ethiopia has a huge livestock population, including sheep, that has been contributing a considerable portion to the economy of the country and still promising to rally around the economic advancement of the country. However, feed shortage is a limiting factor in the production and productivity of sheep among Ethiopian smallholder farmers. Therefore, the aim of this study was to prove the role of the locally available brewery by-products called dried Atella as a supplement in feed intake, digestibility, live weight gain, carcass yield, and economic benefit in comparison with commercially purchased supplements known as niger seed cake (NSC). This on-station feeding experiment was conducted on the Zenzelma Campus of Bahir Dar University animal farm. The experimental design used for this research was a completely randomized design (CRD) with five replications. The crude protein (CP) content of dried Atella, wheat bran (WB), natural pasture hay (NPH) and NSC were about 25.07%, 16.57%, 4.48% and 38.04%, respectively, while the neutral detergent fibre (NDF),acid detergent fibre (ADF) and acid detergent lignin (ADL) content of dried Atella, WB, NPH and NSC were around 31.75%, 8.31%, 8.14%; 42.05%, 22.64%, 4.04%; 74.21%, 50.81%, 8.66%; 42.31%, 26.95% and 6.9%, respectively. The result depicted that a higher(P < 0.001) feed intake, nutrient intake, and digestibility for lambs supplemented with Atella than those supplemented with NSC. Furthermore, daily body weight gain and carcass characteristics were better (P < 0.05) for the sheep supplemented with dried Atella than NSC. On the other hand, in terms of profitability, although there was no substantial difference (P > 0.05) between T2 (animals fed NPH,NSC and WB) and T3 (animals fed NPH, Atella and WB), slightly better benefit was recorded in T3 groups. However, loss of money was recorded in T1 (animals fed NPH and WB). Hence, from the biological performance of lambs, it was concluded that Atella could be a potential supplementary feed for sheep fattening among smallholder farmers than NSC despite no profitability difference. Nevertheless, further investigation is recommended to examine the consequence of supplementation of NPH with NSC and NPH with Atella on fatty acid profile analysis, the physicochemical composition of meat, and meat composition.

Keywords: Attela, Bahir Dar university, Carcass yield, digestibility, natural pasture hay, Niger seed cake, smallholder farmers, weight gain, Ethiopia

Procedia PDF Downloads 150

Authors: B. Mahfoud, A. Bendjagloli

Abstract:

The effect of an axial magnetic field on the flow produced by co-rotation of the top and bottom disks in a vertical cylindrical heated from below is numerically analyzed. The governing Navier-Stokes, energy, and potential equations are solved by using the finite-volume method. It was observed that the Reynolds number is increased, the axisymmetric basic state loses stability to circular patterns of axisymmetric vortices and spiral waves. In mixed convection case the axisymmetric mode disappears giving an asymmetric mode m=1. It was also found that the primary thresholds Recr corresponding to the modes m=1and 2, increase with increasing of the Hartmann number (Ha). Finally, stability diagrams have been established according to the numerical results of this investigation. These diagrams giving the evolution of the primary thresholds as a function of the Hartmann number for various values of the Richardson number.

Keywords: bifurcation, co-rotating end disks, magnetic field, stability diagrams, vortices

Procedia PDF Downloads 348

Authors: Milind Anurag

Abstract:

This study investigates cutting-edge truss design improvements, which are specifically adapted to satisfy the structural demands and difficulties associated with high-performance facades and roofs in modern architectural environments. With a growing emphasis on sustainability, energy efficiency, and eye-catching architectural aesthetics, the structural components that support these characteristics play an important part in attaining the right balance of form and function. The paper seeks to contribute to the evolution of truss design methods by combining data from these investigations, giving significant insights for architects, engineers, and researchers interested in the creation of high-performance building envelopes. The findings of this study are meant to inform future design standards and practices, promoting the development of structures that seamlessly integrate architectural innovation with structural robustness and environmental responsibility.

Keywords: truss design, high-performance, facades, finite element analysis, structural efficiency

Procedia PDF Downloads 55

Authors: H. J. Kim, G. C. Park, K. C. Kim, J. H. Shin

Abstract:

Cavities are frequently found beneath conduits on pile foundations in old embankments. Cavity reduces seepage length significantly and consequently causes piping failure of embankments. Case studies of embankment failures indicate that the relative settlement between ground and pile supported-concrete conduit was the main reason of the cavity. In this paper, an attempt to simulate the cavity-induced piping failure mechanism was made using finite element numerical method. Piping potential is examined by carrying out parametric study for influencing factors such as cavity length, water level, and flow conditions. The concentration of hydraulic gradient adjacent to cavity was found. It is found that the hydraulic gradient close to the cavity exceeds considerably the critical hydraulic gradient causing piping. Piping failure potential due to the existence of cavity is evaluated and contour map for the potential risk of an embankment for piping failure is proposed.

Keywords: cavity, hydraulic gradient, levee, piping

Procedia PDF Downloads 520

Authors: Viliam Makis, Farnoosh Naderkhani, Leila Jafari

Abstract:

In this paper, we present a model and an algorithm for the calculation of the optimal control limit, average cost, sample size, and the sampling interval for an optimal Bayesian chart to control the proportion of defective items produced using a semi-Markov decision process approach. Traditional p-chart has been widely used for controlling the proportion of defectives in various kinds of production processes for many years. It is well known that traditional non-Bayesian charts are not optimal, but very few optimal Bayesian control charts have been developed in the literature, mostly considering finite horizon. The objective of this paper is to develop a fast computational algorithm to obtain the optimal parameters of a Bayesian p-chart. The decision problem is formulated in the partially observable framework and the developed algorithm is illustrated by a numerical example.

Keywords: Bayesian control chart, semi-Markov decision process, quality control, partially observable process

Procedia PDF Downloads 319

Authors: Fahad Al Yahyaey, Ihab Shaat, Russell Bush

Abstract:

This study was conducted at the Livestock Research Centre, Ministry of Agriculture and Fisheries, Oman, on two local goat breeds (Jabbali and Sahrawi) due to their importance to Omani livestock production and food security. The Jabbali is characterized by increased growth rates and a higher twinning rate, while the Sahrawi has increased milk production. The aim of the study was to investigate the effect of Spirulina supplementation on live weight (BWT), average daily gain (ADG), and body conformation measurements; chest girth (CG), wither height (WH), body length (BL), and body condition score (BCS). Thirty-six males (approximately nine-months-old and 16.44 ± 0.33 kg average of initial body weight) were used across an eleven-week study from November–February 2019-2020. Each breed was divided into three groups (n = 6/group) and fed one of three rations: (1) concentrate mixture (Control) with crude protein 14% and energy 11.97% MJ/kg DM; (2) the same concentrate feed with the addition of 2 gm /capita daily Spirulina platensis (Treatment 1) and (3) the same concentrate feed with the addition of 4 gm /capita daily Spirulina platensis (Treatment 2). Analysis of weekly data collections for all traits indicated a significant effect of feeding Spirulina on all the studied traits except WH and BL. Analysis of variance for fixed effects in this study (damage and kid birth type i.e., single, twin or triple) were not significant for all studied traits. However, the breed effect was highly significant (P < 0.001) on BWT, ADG, BCS, and CG traits. On the other hand, when the analysis was done for the treatment effect within breeds for ADG, the Sahrawi breed had a significant effect (P < 0.05) at 56.52, 85.51, and 85.50 g/day for control, treatment 1 and treatment 2, respectively. This is a 51% difference between the control and treatment 1 (2 gm /capita). Whereas for the Jabbali breed, the treatment effect was not significant for ADG (P =0.55), and the actual ADG was 104.59, 118.84, and 114.25 g/day for control, treatment 1, and treatment 2, respectively, providing a 14% difference between the control group and the treated group (4 gm /capita). These findings indicate using Spirulina supplementation in Omani goat diets is recommended at 2 gm per capita as there was no benefit in feeding at 4 gm per capita for either breed. Farmers feeding Spirulina supplementation to kids after weaning at six-months could increase their herd performance and growth rate and facilitate buck selection at an earlier age.

Keywords: body conformation, goats, live weight, spirulina

Procedia PDF Downloads 112

Authors: Ali Atashbar Orang, Carlo Massimo Casciola

Abstract:

A novel numerical approach for the steady incompressible turbulent flows is presented in this paper. The artificial compressibility method (ACM) is applied to the Reynolds Averaged Navier-Stokes (RANS) equations. A new Characteristic-Based Turbulent (CBT) scheme is developed for the convective fluxes. The well-known Spalart–Allmaras turbulence model is employed to check the effectiveness of this new scheme. Comparing the proposed scheme with previous studies, it is found that the present CBT scheme demonstrates accurate results, high stability and faster convergence. In addition, the local time stepping and implicit residual smoothing are applied as the convergence acceleration techniques. The turbulent flows past a backward facing step, circular cylinder, and NACA0012 hydrofoil are studied as benchmarks. Results compare favorably with those of other available schemes.

Keywords: incompressible turbulent flow, method of characteristics, finite volume, Spalart–Allmaras turbulence model

Procedia PDF Downloads 412

Authors: Mahdi Eskandarlou, Mehrdad Taghipour

Abstract:

Background: Partial-thickness skin graft is the cornerstone for scalp defect repair. Routine donor sites include abdomen, thighs, and buttocks. Given the potential side effects following harvesting from these sites and the potential advantages of harvesting from scalp (broad surface, rapid healing, and better cosmetics results), this study is trying to compare the outcomes of graft harvesting from scalp and lower limb. Methods: This clinical trial is conducted among a sample number of 40 partial thickness graft candidates (20 case and 20 control group) with scalp defect presenting to plastic surgery clinic at Besat Hospital during the time period between 2018 and 2019. Sampling was done by simple randomization using random digit table. Data gathering was performed using a designated checklist. The donor site in case group and control group was scalp and lower limb, respectively. The resultant data were analyzed using chi-squared and t-test and SPPS version 21 (SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp). Results: Of the total 40 patients participating in this study, 28 patients (70%) were male, and 12 (30%) were female with and mean age of 63.62 ± 09.73 years. Hypertension and diabetes mellitus were the most common comorbidities among patients with basal cell carcinoma (BCC) and trauma being the most common etiology for the defects. There was a statistically meaningful relationship between two groups regarding the etiology of defect (P=0.02). The most common anatomic location of defect for case and control groups was temporal and parietal, respectively. Most of the defects were deep to galea zone. The mean diameter of defect was 24.28 ± 45.37 mm for all of the patients. The difference between diameter of defect in both groups was statistically meaningful, while no such difference between graft diameter was seen. The graft 'Take' was completely successful in both groups according to evaluations. The level of postoperative pain was lower in the case group compared to the control according to VAS scale, and the satisfaction was higher in them per Likert scale. Conclusion: Scalp can safely be used as donor site for skin graft to be used for scalp defects, which is associated with better results and lower complication rates compared to other donor sites.

Keywords: donor site, leg, partial-thickness graft, scalp

Procedia PDF Downloads 150