Search results for: solitary wave solutions

Authors: Karim S. Hassan, Hisham M. Hamed, Yassmine A. Fahmy, Ahmed F. Shalash

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The mismatch between in-phase and quadrature signals in Orthogonal frequency division multiplexing (OFDM) systems, such as DVB-T2, results in a severe degradation in performance. Several general solutions have been proposed in the past, but these are largely computationally intensive, leading to complex implementations. In this paper, we propose a relatively simple iterative solution, which provides good results in relatively few iterations, using fixed precision arithmetic. An additional advantage is that complex digital blocks, such as dividers and square root, are not required. Thus, the proposed solution may be implemented in relatively simple hardware.

Keywords: OFDM, DVB-T2, I/Q imbalance, I/Q mismatch, iterative method, fixed point, reduced complexity

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Authors: Sana Almi, Djamel Barkat

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The solvent extraction of cobalt (II) and nickel (II) from aqueous sulfate solutions were investigated with the analytical methods of slope analysis using salicylidene aniline and the three isomeric o-, m- and p-salicylidene toluidine diluted with chloroform at 25°C. By a statistical analysis of the extraction data, it was concluded that the extracted species are CoL2 with CoL2(HL) and NiL2 (HL denotes HSA, HSOT, HSMT, and HSPT). The extraction efficiency of Co(II) was higher than Ni(II). This tendency is confirmed from numerical extraction constants for each metal cations. The best extraction was according to the following order: HSMT > HSPT > HSOT > HSA for Co2+ and Ni2+.

Keywords: solvent extraction, nickel(II), cobalt(II), salicylidene aniline, o-, m-, and p-salicylidene toluidine

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Authors: John Davidson, Matteo Castelletti, Ismael Torres, Victor Terente, Jamie Irvine, Sylvie Raymackers

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The current industry approach to pile driving predictions consists of developing a model of the hammer-pile-soil system which simulates the relationship between soil resistance to driving (SRD) and blow counts (or pile penetration per blow). The SRD methods traditionally used are broadly based on static pile capacity calculations. The SRD is used in combination with the one-dimensional wave equation model to indicate the anticipated blowcounts with depth for specific hammer energy settings. This approach has predominantly been calibrated on relatively long slender piles used in the oil and gas industry but is now being extended to allow calculations to be undertaken for relatively short rigid large diameter monopile foundations. This paper evaluates the accuracy of current industry practice when applied to a site where large diameter monopiles were installed in predominantly stiff fissured clay. Actual geotechnical and pile installation data, including pile driving records and signal matching analysis (based upon pile driving monitoring techniques), were used for the assessment on the case study site.

Keywords: driven piles, fissured clay, London clay, monopiles, offshore foundations

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Authors: Alex Fedoseyev

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This study investigates a generalized hydrodynamic equation (GHE) simplified model for the simulation of turbulent flow over a two-dimensional backward-facing step (BFS) at Reynolds number Re=132000. The GHE were derived from the generalized Boltzmann equation (GBE). GBE was obtained by first principles from the chain of Bogolubov kinetic equations and considers particles of finite dimensions. The GHE has additional terms, temporal and spatial fluctuations, compared to the Navier-Stokes equations (NSE). These terms have a timescale multiplier τ, and the GHE becomes the NSE when $\tau$ is zero. The nondimensional τ is a product of the Reynolds number and the squared length scale ratio, τ=Re*(l/L)², where l is the apparent Kolmogorov length scale, and L is a hydrodynamic length scale. The BFS flow modeling results obtained by 2D calculations cannot match the experimental data for Re>450. One or two additional equations are required for the turbulence model to be added to the NSE, which typically has two to five parameters to be tuned for specific problems. It is shown that the GHE does not require an additional turbulence model, whereas the turbulent velocity results are in good agreement with the experimental results. A review of several studies on the simulation of flow over the BFS from 1980 to 2023 is provided. Most of these studies used different turbulence models when Re>1000. In this study, the 2D turbulent flow over a BFS with height H=L/3 (where L is the channel height) at Reynolds number Re=132000 was investigated using numerical solutions of the GHE (by a finite-element method) and compared to the solutions from the Navier-Stokes equations, k–ε turbulence model, and experimental results. The comparison included the velocity profiles at X/L=5.33 (near the end of the recirculation zone, available from the experiment), recirculation zone length, and velocity flow field. The mean velocity of NSE was obtained by averaging the solution over the number of time steps. The solution with a standard k −ε model shows a velocity profile at X/L=5.33, which has no backward flow. A standard k−ε model underpredicts the experimental recirculation zone length X/L=7.0∓0.5 by a substantial amount of 20-25%, and a more sophisticated turbulence model is needed for this problem. The obtained data confirm that the GHE results are in good agreement with the experimental results for turbulent flow over two-dimensional BFS. A turbulence model was not required in this case. The computations were stable. The solution time for the GHE is the same or less than that for the NSE and significantly less than that for the NSE with the turbulence model. The proposed approach was limited to 2D and only one Reynolds number. Further work will extend this approach to 3D flow and a higher Re.

Keywords: backward-facing step, comparison with experimental data, generalized hydrodynamic equations, separation, reattachment, turbulent flow

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Authors: Nihat Dipova, Bulent Cangir

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This article presents the results of probabilistic seismic hazard analysis (PSHA) for Antalya (SW Turkey). South west of Turkey is characterized by large earthquakes resulting from the continental collision between the African, Arabian and Eurasian plates and crustal faults. Earthquakes around the study area are grouped into two; crustal earthquakes (D=0-50 km) and subduction zone earthquakes (50-140 km). Maximum observed magnitude of subduction earthquakes is Mw=6.0. Maximum magnitude of crustal earthquakes is Mw=6.6. Sources for crustal earthquakes are faults which are related with Isparta Angle and Cyprus Arc tectonic structures. A new earthquake catalogue for Antalya, with unified moment magnitude scale has been prepared and seismicity of the area around Antalya city has been evaluated by defining ‘a’ and ‘b’ parameters of the Gutenberg-Richter recurrence relationship. The Standard Cornell-McGuire method has been used for hazard computation utilizing CRISIS2007 software. Attenuation relationships proposed by Chiou and Youngs (2008) has been used for 0-50 km earthquakes and Youngs et. al (1997) for deep subduction earthquakes. Finally, Seismic hazard map for peak horizontal acceleration on a uniform site condition of firm rock (average shear wave velocity of about 1130 m/s) at a hazard level of 10% probability of exceedance in 50 years has been prepared.

Keywords: Antalya, peak ground acceleration, seismic hazard assessment, subduction

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Authors: G. B. M. Carvalho, V. A. C. Vale, E. T. L. Cöuras Ford

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With the aim of increasing the levels of comfort and security structures, the study of dynamic loads on buildings has been one of the focuses in the area of control engineering, civil engineering and architecture. Thus, this work presents a study based on simulation of the dynamics of buildings in the form of portico subjected to wind action, besides presenting an action of passive control, using for this the dynamics of the structure, consequently representing a system appropriated on environmental issues. These control systems are named the dynamic vibration absorbers.

Keywords: dynamic vibration absorber, structure, comfort, safety, wind behavior, structure

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Authors: Jaegu Choi, Jae-Mean Koo, Chang-Sung Seok, Byungwoo Moon

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Since massive earthquakes in the world have been reported recently, the safety of nuclear power plants for seismic loading has become a significant issue. Seismic loading is the reverse cyclic loading, consisting of repeated tensile and compression by longitudinal and transverse wave. Up to this time, the study on characteristics of fracture toughness under reverse cyclic loading has been unsatisfactory. Therefore, it is necessary to obtain the fracture toughness under reverse cyclic load for the integrity estimation of nuclear power plants under seismic load. Fracture resistance (J-R) curves, which are used for determination of fracture toughness or integrity estimation in terms of elastic-plastic fracture mechanics, can be derived by the fracture resistance test using single specimen technique. The objective of this paper is to study the effects of reverse cyclic loading on a fracture resistance curve of ESG specimen, having a similar stress gradient compared to the crack surface of the real pipe. For this, we carried out the fracture toughness test under the reverse cyclic loading, while changing incremental plastic displacement. Test results showed that the J-R curves were decreased with a decrease of the incremental plastic displacement.

Keywords: reverse cyclic loading, j-r curve, ESG specimen, incremental plastic displacement

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Authors: Ahmet Faruk Akyuz, Hasan Sakir Bilge

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Depth estimation using stereo images is a challenging problem in computer vision. Many different studies have been carried out to solve this problem. With advancing machine learning, tackling this problem is often done with neural network-based solutions. The images used in these studies are mostly in the visible spectrum. However, the need to use the Infrared (IR) spectrum for depth estimation has emerged because it gives better results than visible spectra in some conditions. At this point, we recommend using thermal-thermal (IR) image pairs for depth estimation. In this study, we used two well-known networks (PSMNet, FADNet) with minor modifications to demonstrate the viability of this idea.

Keywords: thermal stereo matching, deep neural networks, CNN, Depth estimation

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Authors: Nguyen Quang Bau, Nguyen Thu Huong, Dang Thi Thanh Thuy

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The analytic expression for the Hall Coefficient (HC) caused by the confined electrons in the presence of a strong electromagnetic wave (EMW) including the effect of phonon confinement in rectangular quantum wires (RQWs) is calculated by using the quantum kinetic equation for electrons in the case of electron - optical phonon scattering. It is because the expression of the HC for the confined phonon case contains indexes m, m’ which are specific to the phonon confinement. The expression in a RQW is different from that for the case of unconfined phonons in a RQW or in 2D. The results are numerically calculated and discussed for a GaAs/GaAsAl RQW. The numerical results show that HC in a RQW can have both negative and positive values. This is different from the case of the absence of EMW and the case presence of EMW including the effect of phonon unconfinement in a RQW. These results are also compared with those in the case of unconfined phonons in a RQW and confined phonons in a quantum well. The conductivity in the case of confined phonon has more resonance peaks compared with that in case of unconfined phonons in a RQW. This new property is the same in quantum well. All results are compared with the case of unconfined phonons to see differences.

Keywords: Hall coefficient, rectangular quantum wires, electron-optical phonon interaction, quantum kinetic equation, confined phonons

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Authors: Soufiene Ilahi

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Photothermal effect occurs when absorbed light energy that generate a thermal wave that propagate into the sample and surrounding media. Subsequently, the propagation of the vibration of phonons or electrons causes heat transfer. In fact, heat energy is provided by non-radiative recombination process that occurs in semiconductors sample. Three heats sources are identified: surface recombination, bulk recombination and carrier thermalisation. In the last few years, Photothermal Deflection Technique PTD is a nondestructive and accurate technique that prove t ability for electronics properties investigation. In this paper, we have studied the influence of doping on minority carrier lifetime, i.e, nonradiative lifetime, surface and diffusion coefficient. In fact, we have measured the photothermal signal of two sample of GaAs doped with C et Cr.In other hand , we have developed a theoretical model that takes into account of thermal and electronics diffusion equations .In order to extract electronics parameters of GaAs samples, we have fitted the theoretical signal of PTD to the experimental ones. As a results, we have found that nonradiative lifetime is around of 4,3 x 10-8 (±11,24%) and 5 x 10-8 (±14,32%) respectively for GaAs : Si doped and Cr doped. Accordingly, the diffusion coefficient is equal 4,6 *10-4 (± 3,2%) and 5* 10-4 (± 0,14%) foe the Cr, C and Si doped GaAs respectively.

Keywords: nonradiative lifetime, mobility of minority carrier, diffusion length, surface and interface recombination in GaAs

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Authors: Vidya Nimkar Tayade

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Introduction: Intellectual capital of an organization is a key factor to success. Many companies invest a huge amount in their Research and development activities. Any innovation is helpful not only to that particular company but also to many other companies, industry and mankind as a whole. Companies undertake innovative changes for increasing their capital profitability and indirectly increase in pay packages of their employees. The quality of human capital can also improve due to such positive changes. Employees become more skilled and experienced due to such innovations and inventions. For increasing intangible capital, the author has referred to a couple of books and referred case studies to come to a conclusion. Different charts and tables are also referred to by the author. Case studies are more important because they are proven and established techniques. They enable students to apply theoretical concepts in real-world situations. It gives solutions to an open-ended problem with multiple potential solutions. There are three different strategies for undertaking intellectual capital increase. They are: Research push strategy/ Technology pushed approach, Market pull strategy/ approach and Open innovation strategy/approach. Research push strategy, In this strategy, research is undertaken and innovation is achieved on its own. After invention inventor company protects such invention and finds buyers for such invention. In this way, the invention is pushed into the market. In this method, research and development are undertaken first and the outcome of this research is commercialized. Market pull strategy, In this strategy, commercial opportunities are identified first and our research is concentrated in that particular area. For solving a particular problem, research is undertaken. It becomes easier to commercialize this type of invention. Because what is the problem is identified first and in that direction, research and development activities are carried on. Open invention strategy, In this type of research, more than one company enters into an agreement of research. The benefits of the outcome of this research will be shared by both companies. Internal and external ideas and technologies are involved. These ideas are coordinated and then they are commercialized. Due to globalization, people from the outside company are also invited to undertake research and development activities. Remuneration of employees of both the companies can increase and the benefit of commercialization of such invention is also shared by both the companies. Conclusion: In modern days, not only can tangible assets be commercialized, but also intangible assets can also be commercialized. The benefits of such an invention can be shared by more than one company. Competition can become more meaningful. Pay packages of employees can improve. It Is a need for time to adopt such strategies to benefit employees, competitors, stakeholders.

Keywords: innovation, protection, management, commercialization

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Authors: Naif Mohsen Alharbi

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This paper present failure occurred on flexible coupling installed at oil anf gas operation. Also it presents maintenance ideas implemented on the flexible coupling installed to transmit high torque from gearbox to pump. Basically, the machine train is including steam turbine which drives the pump and there is gearbox located in between for speed reduction. investigation are identifying the root causes, solving and developing the technology designs or bad actor. This report provides the study intentionally for continues operation optimization, utilize the advanced opportunity and implement a improvement. Objective: The main objectives of the investigation are identifying the root causes, solving and developing the technology designs or bad actor. Ultimately, fulfilling the operation productivity, also ensuring better technology, quality and design by solutions. This report provides the study intentionally for continues operation optimization, utilize the advanced opportunity and implemet improvement. Method: The method used in this project was a very focused root cause analysis procedure that incorporated engineering analysis and measurements. The analysis method extensively covers the measuring of the complete coupling dimensions. Including the membranes thickness, hubs, bore diameter and total length, dismantle flexible coupling to diagnose how deep the coupling has been affected. Also, defining failure modes, so that the causes could be identified and verified. Moreover, Vibration analysis and metallurgy test. Lastly applying several solutions by advanced tools (will be mentioned in detail). Results and observation: Design capacity: Coupling capacity is an inadequate to fulfil 100% of operating conditions. Therefore, design modification of service factor to be at least 2.07 is crucial to address this issue and prevent recurrence of similar scenario, especially for the new upgrading project. Discharge fluctuation: High torque flexible coupling encountered during the operation. Therefore, discharge valve behaviour, tuning, set point and general conditions revaluated and modified subsequently, it can be used as baseline for upcoming Coupling design project. Metallurgy test: Material of flexible coupling membrane (discs) tested at the lab, for a detailed metallurgical investigation, better material grade has been selected for our operating conditions,

Keywords: high speed machine, reliabilty, flexible coupling, rotating equipment

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Authors: Jessica Lopez Espejel, Mahaman Sanoussi Yahaya Alassan, Walid Dahhane, El Hassane Ettifouri

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Pretrained transformer-based models have shown high performance in natural language generation tasks. However, a new wave of interest has surged: automatic programming language code generation. This task consists of translating natural language instructions to a source code. Despite the fact that well-known pre-trained models on language generation have achieved good performance in learning programming languages, effort is still needed in automatic code generation. In this paper, we introduce JaCoText, a model based on Transformer neural network. It aims to generate java source code from natural language text. JaCoText leverages the advantages of both natural language and code generation models. More specifically, we study some findings from state of the art and use them to (1) initialize our model from powerful pre-trained models, (2) explore additional pretraining on our java dataset, (3) lead experiments combining the unimodal and bimodal data in training, and (4) scale the input and output length during the fine-tuning of the model. Conducted experiments on CONCODE dataset show that JaCoText achieves new state-of-the-art results.

Keywords: java code generation, natural language processing, sequence-to-sequence models, transformer neural networks

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Authors: Shirin Sarejloo

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Background: Electrophysiological-related manifestation of COVID-19 is a matter of debate in the literature nowadays. A wide spectrum of arrhythmias was observed among patients who have been infected with COVID-19. Objectives: This study discussed the prevalence of arrhythmias and conduction system disease in patients with COVID-19. Method: In this retrospective study, demographic and electrocardiographic data of 432 expired COVID-19 patients who had been admitted to Faghihi Hospital of Shiraz University of Medical Sciences from August2020 until December 2020 were reviewed. Results: Atrioventricular nodal block (AVB) was found in 40(9.3%) patients. Furthermore, 28(6.5%) of them suffered from the first degree of AVB, and 12(2.8%) suffered from complete heart block (CHB). Among 189 cases (59.0%), ST-T changes agreed with myocardial infarction or localized myocarditis. Findings of myocardial injury, including fragmented QRS and prolonged QTc were observed among 91 (21.1%) and 28 (6.5%), respectively. In victims of COVID-19, conduction disease was not related to any comorbidities. Fragmented QRS, axis deviation, presence of S1Q3T3, and poor R wave progression were significantly related to conduction system abnormalities in victims of COVID-19 (P-value > 0.05). Conclusion: Our findings can serve in future studies that aim to develop a risk stratification method for susceptible COVID-19 patients. The myocardial injury appears to role significantly in COVID-19 morbidity and mortality. Consequently, we recommend health policymakers consider separate catheterization laboratories that provide service only to COVID-19 patients.

Keywords: COVID-19, conduction system, ECG, atrioventricular block

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Authors: Meriem Harmel, Houari Khachai

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The full potential linearized augmented plane wave (FP-LAPW)method within density functional theory is applied to study, for the first time, the structural and electronic properties of CaFI and to compare them with CaFCl and CaFBr, all compounds belonging to the tetragonal PbFCl structure group with space group P4/nmm. We used the generalized gradient approximation (GGA) based on exchange–correlation energy optimization to calculate the total energy and also the Engel– Vosko GGA formalism, which optimizes the corresponding potential for band structure calculations. Ground state properties such as the lattice parameters, c/a ratio, bulk modulus, pressure derivative of the bulk modulus and cohesive energy are calculated, as well as the optimized internal parameters, by relaxing the atomic position in the force directions. The variations of the calculated interatomic distances and angles between different atomic bonds are discussed. CaFCl was found to have a direct band gap at whereas CaFBr and BaFI have indirect band gaps. From these computed bands, all three materials are found to be insulators having band gaps of 6.28, 5.46, and 4.50 eV, respectively. We also calculated the valence charge density and the total density of states at equilibrium volume for each compound. The results are in reasonable agreement with the available experimental data.

Keywords: DFT, matlockite, structural properties, electronic structure

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Authors: Alicja Starczewska, Aleksander Nawrat, Krzysztof Daniec, Jarosław Homa, Kacper Hołda

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Border Gateway Protocol is the main routing protocol that enables routing establishment between all autonomous systems, which are the basic administrative units of the internet. Due to the poor protection of BGP, it is important to use additional BGP security systems. Many solutions to this problem have been proposed over the years, but none of them have been implemented on a global scale. This article describes a system capable of building images of real-time BGP network topology in order to detect BGP anomalies. Our proposal performs a detailed analysis of BGP messages that come into local network cards supplemented by information collected by remote collectors in different localizations.

Keywords: BGP, BGP hijacking, cybersecurity, detection

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Authors: Guo Haonan, Chen Peiyu, Zhao Hanyu, Burra Venkata Durga Kumar

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Unix and Unix-like operating systems are widely used due to their high stability but are limited by the parent-child process structure, and the child process depends on the parent process, so the crash of a single process may cause the entire process group or even the entire system to fail. Another possibility of unexpected process termination is that the system administrator inadvertently closed the terminal or pseudo-terminal where the application was launched, causing the application process to terminate unexpectedly. This paper mainly analyzes the reasons for the problems and proposes two solutions.

Keywords: process management, daemon, login-bash and non-login bash, process group

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Authors: Thair Mahmood Altaiee

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Because of the increasing population and the growing water requirements from the transboundary water resources within riparian countries in addition to un-proper management of these transboundary water resources, it is likely that a conflicts on the water will be occurred. So it is mandatory to search solutions to mitigate the action and probabilities of these undesired conflicts. One of the solutions for these crises may be sharing the riparian countries in the management of their transboundary water resources and share benefit. Effective cooperation on a transboundary river is any action by the riparian countries that lead to improve management of the river to their mutual acceptance. In principle, friendship dams constructed by riparian countries may play an important role in preventing conflicts like the Turkish-Syrian friendship dam on Asi river (Orontes), Iranian-Tukmenistan dam on Hariroud river, Bulgarian-Turkish dam on Tundzha river, Brazil-Paraguay dam on Parana river, and Aras dam between Iran and Azerbaijan. The objective of this study is to focus the light on the hydrological aspects of cooperation in constructing dams on the transboundary rivers, which may consider an option to prevent conflicts on water between the riparian countries. The various kinds of benefits and external impacts associated with cooperation in dams construction on the transboundary rivers with a real examples will be presented and analyzed. The hydrological benefit sharing from cooperation in dams construction, which type of benefit sharing mechanisms are applicable to dams, and how they vary were discussed. The study considered the cooperative applicability to dams on shared rivers according to selected case study of friendship dams in the world to illustrate the relevance of the cooperation concepts and the feasibility of such propose cooperation between Turkey and Iraq within the Tigris river. It is found that the opportunities of getting benefit from cooperation depend mainly on the hydrological boundary and location of the dam in relation to them. The desire to cooperate on dams construction on transboundary rivers exists if the location of a dam upstream will increase aggregate net benefits. The case studies show that various benefit sharing mechanisms due to cooperation in constructing friendship dams on the riparian countries border are possible for example when the downstream state (Iraq) convinces the upstream state (Turkey) to share building a dam on Tigris river across the Iraqi –Turkish border covering the cost and sharing the net benefit derived from this dam. These initial findings may provide guidance for riparian states engaged in and donors facilitating negotiation on dam projects on transboundary rivers.

Keywords: friendship dams, transboundary rivers, water cooperation, benefit sharing

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Authors: Somveer Singh, Vineet Kumar Singh

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We present a new model based on viscoelasticity for the Non-Newtonian fluids.We use a matrix formulated algorithm to approximate solutions of a class of partial integro-differential equations with the given initial and boundary conditions. Some numerical results are presented to simplify application of operational matrix formulation and reduce the computational cost. Convergence analysis, error estimation and numerical stability of the method are also investigated. Finally, some test examples are given to demonstrate accuracy and efficiency of the proposed method.

Keywords: Legendre Wavelets, operational matrices, partial integro-differential equation, viscoelasticity

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Authors: A. Abada, S. Hiadsi, T. Ouahrani, B. Amrani, K. Amara

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Using the first-principles full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method based on density functional theory (DFT), we have investigated the electronic structure and magnetism of some Co2- based full Heusler alloys, namely Co2ZrGe and Co2NbB. The calculations show that these compounds are to be half-metallic ferromagnets (HMFs) with a total magnetic moment of 2.000 µB per formula unit, well consistent with the Slater-Pauling rule. Our calculations show indirect band gaps of 0.58 eV and 0.47 eV in the minority spin channel of density of states (DOS) for Co2ZrGe and Co2NbB, respectively. Analysis of the DOS and magnetic moments indicates that their magnetism is mainly related to the d-d hybridization between the Co and Zr (or Nb) atoms. The half metallicity is found to be robust against volume changes and the two alloys kept a 100% of spin polarization at the Fermi level. In addition, an atom inside molecule AIM formalism and an electron localization function ELF were also adopted to study the bonding properties of these compounds, building a bridge between their electronic and bonding behavior. As they have a good crystallographic compatibility with the lattice of semiconductors used industrially and negative calculated cohesive energies with considerable absolute values these two alloys could be promising magnetic materials in the spintronics field.

Keywords: half-metallic ferromagnets, full Heusler alloys, magnetic properties, electronic properties

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Authors: Cagri Mollamahmutoglu, Aykut Levent, Ali Mercan

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Micro-beams are one of the most common components of Nano-Electromechanical Systems (NEMS) and Micro Electromechanical Systems (MEMS). For this reason, static bending, buckling, and free vibration analysis of micro-beams have been the subject of many studies. In addition, micro-beams restrained with elastic type foundations have been of particular interest. In the analysis of microstructures, closed-form solutions are proposed when available, but most of the time solutions are based on numerical methods due to the complex nature of the resulting differential equations. Thus, a robust and efficient solution method has great importance. In this study, a mixed finite element formulation is obtained for a functionally graded Timoshenko micro-beam resting on two-parameter elastic foundation. In the formulation modified couple stress theory is utilized for the micro-scale effects. The equation of motion and boundary conditions are derived according to Hamilton’s principle. A functional, derived through a scientific procedure based on Gateaux Differential, is proposed for the bending and buckling analysis which is equivalent to the governing equations and boundary conditions. Most important advantage of the formulation is that the mixed finite element formulation allows usage of C₀ type continuous shape functions. Thus shear-locking is avoided in a built-in manner. Also, element matrices are sparsely populated and can be easily calculated with closed-form integration. In this framework results concerning the effects of micro-scale length parameter, power-law parameter, aspect ratio and coefficients of partially or fully continuous elastic foundation over the static bending, buckling, and free vibration response of FG-micro-beam under various boundary conditions are presented and compared with existing literature. Performance characteristics of the presented formulation were evaluated concerning other numerical methods such as generalized differential quadrature method (GDQM). It is found that with less computational burden similar convergence characteristics were obtained. Moreover, formulation also includes a direct calculation of the micro-scale related contributions to the structural response as well.

Keywords: micro-beam, functionally graded materials, two-paramater elastic foundation, mixed finite element method

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Authors: Catherine Chua, Kashif Raza

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Work-integrated learning (WIL) has been heightened in the last few years across countries. With a specific attention on working adults, the key objective is to integrate work experiences with academic studies so that they will be given more opportunities to advance, gather relevant skills and credentials to enable them to contribute more positively to the labour market. In Singapore, developing talent through WIL aims to develop specialist and enduring skills for the industries. Collaborating with the institutes of higher education in Singapore, the Integrated Work Study Programs (IWSP) seek to harmonize classroom learning with practical work experiences so that adult students can develop skills and knowledge that are needed in the existing and future workplaces. Local higher education institutions will also work closely with industry partners, and design courses that support these students to deepen their skills. Using Critical Discourse Analysis, this paper examines the Singapore government policies in WIL and argues that despite the various supports and interventions provided by the government, it is equally important to create a ‘space’ in the society whereby there is a greater recognition for WIL as a valuable education approach, i.e., “continuous meritocracy”. This is especially so in Singapore where academic excellence and conventional front-loaded approach to education are valued.

Keywords: work-integrated learning, adult learners, continuous meritocracy, skillsfuture singapore

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Authors: A. Schuchter, M. Promegger

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The outbreak of the COVID-19 pandemic has shown us that online education is so much more than just a cool feature for teachers – it is an essential part of modern teaching. In online math teaching, it is common to use tools to share screens, compute and calculate mathematical examples, while the students can watch the process. On the other hand, flipped classroom models are on the rise, with their focus on how students can gather knowledge by watching videos and on the teacher’s use of technological tools for information transfer. This paper proposes a co-educational teaching approach for coding and engineering subjects with the help of drone-building to spark interest in technology and create a platform for knowledge transfer. The project combines aspects from mathematics (matrices, vectors, shaders, trigonometry), physics (force, pressure and rotation) and coding (computational thinking, block-based programming, JavaScript and Python) and makes use of collaborative-shared 3D Modeling with clara.io, where students create mathematics knowhow. The instructor follows a problem-based learning approach and encourages their students to find solutions in their own time and in their own way, which will help them develop new skills intuitively and boost logically structured thinking. The collaborative aspect of working in groups will help the students develop communication skills as well as structural and computational thinking. Students are not just listeners as in traditional classroom settings, but play an active part in creating content together by compiling a Handbook of Knowledge (called “open book”) with examples and solutions. Before students start calculating, they have to write down all their ideas and working steps in full sentences so other students can easily follow their train of thought. Therefore, students will learn to formulate goals, solve problems, and create a ready-to use product with the help of “reverse engineering”, cross-referencing and creative thinking. The work on drones gives the students the opportunity to create a real-life application with a practical purpose, while going through all stages of product development.

Keywords: flipped classroom, co-creational education, coding, making, drones, co-education, ARCS-model, problem-based learning

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Authors: Oswaldo Otero, Eduardo A. Orozco, Ana M. Herrera

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In this work, we present results from analytical and numerical studies of the electron acceleration by a TE₀₁₁ cylindrical microwave mode in a static homogeneous magnetic field under electron cyclotron resonance (ECR) condition. The stability of the orbits is analyzed using the particle orbit theory. In order to get a better understanding of the interaction wave-particle, we decompose the azimuthally electric field component as the superposition of right and left-hand circular polarization standing waves. The trajectory, energy and phase-shift of the electron are found through a numerical solution of the relativistic Newton-Lorentz equation in a finite difference method by the Boris method. It is shown that an electron longitudinally injected with an energy of 7 keV in a radial position r=Rc/2, being Rc the cavity radius, is accelerated up to energy of 90 keV by an electric field strength of 14 kV/cm and frequency of 2.45 GHz. This energy can be used to produce X-ray for medical imaging. These results can be used as a starting point for study the acceleration of electrons in a magnetic field changing slowly in time (GYRAC), which has some important applications as the electron cyclotron resonance ion proton accelerator (ECR-IPAC) for cancer therapy and to control plasma bunches with relativistic electrons.

Keywords: Boris method, electron cyclotron resonance, finite difference method, particle orbit theory, X-ray

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Authors: Sadam Alwadi

Abstract:

Outlier values become a problem that frequently occurs in the data observation or recording process. Thus, the need for data imputation has become an essential matter. In this work, it will make use of the methods described in the prior work to detect the outlier values based on a collection of stock market data. In order to implement the detection and find some solutions that maybe helpful for investors, real closed price data were obtained from the Amman Stock Exchange (ASE). Tukey and Maximum Overlapping Discrete Wavelet Transform (MODWT) methods will be used to impute the detect the outlier values.

Keywords: outlier values, imputation, stock market data, detecting, estimation

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Authors: Elyas Akbari, Jafar Hasani, Newsha Dehestani, Mohammad Khaleghi, Alireza Moradi

Abstract:

The aim of the present study was to assess the effect of emotional experience induction in the mirror neurons systems (MNS) activity with regard to the spectrum of depressive symptoms. For this purpose, at first stage, 449 students of Kharazmi University of Tehran were selected randomly and completed the second version of the Beck Depression Inventory (BDI-II). Then, 36 students with standard Z-score equal or above +1.5 and equal or equal or below -1.5 were selected to construct two groups of high and low spectrum of depressive symptoms. In the next stage, the basic activity of MNS was recorded (mu wave) before presenting the positive and negative emotional video clips by Electroencephalography (EEG) technique. The findings related to emotion induction (neutral, negative and positive emotion) demonstrated that the activity of recorded mirror neuron areas had a significant difference between the depressive and non-depressive groups. These findings suggest that probably processing of negative emotions in depressive individuals is due to the idea that the mirror neurons in motor cortex matched up the activity of cognitive regions with the person’s schema. Considering the results of the present study, it could be said that the MNS provides a substrate where emotional disorders can be studied and evaluated.

Keywords: emotional experiences, mirror neurons, depressive symptoms, negative and positive emotion

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Authors: Zill-E-Huma, Humaira Siddiqi

Abstract:

This paper comprises of synthesis of thermally stable, mechanically strong polyimides. The polyimides were considered as most diverse class of polymers having unlimited applications. They were widely used as optical wave guides, in aerospace, for gas separation, as biomaterials and in electronics. Here the focus was to increase thermal stability and mechanical strength of polyimides. For this purpose two monomers were synthesized and were further polymerized via anhydrides to polyimides. The monomer diamines were synthesized by nucleophilic attack of aniline/2-fluoro aniline on hydroxy benzaldehydes. The two diamines synthesized were 3-(bis(4-aminophenyl) methyl) phenol (3OHDA) and 4-(bis(4-amino-3-fluorophenyl) methyl) phenol (2F4OHDA). These diamines were then reacted with dianhydrides to get polyimides. Two neat polyimides of both diamines with pyromellitic dianhydride (PMDA) and one neat polyimide of 4'-(Hexafluoroisopropylidene) diphthalic dianhydride (6FDA) with 3OHDA were synthesized. To compare the properties of synthesized polyimides like thermal stability, rigidity, flexibility, toughness etc. a commercial diamine oxydianiline (ODA) was used. Polyimides from oxydianiline were basically rigid. Nine different polyimide blends were synthesized from 3OHDA and commercial diamines ODA to have a better comparison of properties. TGA and mechanical testing results showed that with the increase in the percentage of 3OHDA in comparison to ODA the flexibility, toughness, strength of polyimide, thermal stability goes on increasing. So, synthesized diamines were responsible for improvement of properties of polyimides.

Keywords: diamines, dianhydrides, oxydianiline, polyimides

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Authors: Latif Adnane, C. E. Ait Zaouiat, M. Eddabbah

Abstract:

In Wireless Body Area Networks, the issue of systems lifetime is a big challenge to complete. In this paper, we have tackled this subject to suggest some solutions. For this aim, we have studied some batteries characteristics related to human body temperature. Moreover, we have analyzed a mathematical model which defines sensors lifetime (battery lifetime). Based on this model, we note that the random access increases the energy consumption, because nodes are waking up during the whole superframe period. Results show that using scheduled mode access of IEEE 802.15.6 maximizes the lifetime function, by setting nodes in the sleep mode in the inactive period of transmission.

Keywords: battery, energy consumption, IEEE 802.15.6, lifetime, polling

Procedia PDF Downloads 324

Authors: Riddhiman Sherlekar, Umang Paladia, Rachit Desai, Yash Patel

Abstract:

A number of surfactants which exhibit ultra-low interfacial tension and an excellent microemulsion phase behavior with crude oils of low to medium gravity are not sufficiently soluble at optimum salinity to produce stable aqueous solutions. Such solutions often show phase separation after a few days at reservoir temperature, which does not suffice the purpose and the time is short when compared to the residence time in a reservoir for a surfactant flood. The addition of polymer often exacerbates the problem although the poor stability of the surfactant at high salinity remains a pivotal issue. Surfactants such as SDS, Ctab with large hydrophobes produce lowest IFT, but are often not sufficiently water soluble at desired salinity. Hydrophilic co-solvents and/or co-surfactants are needed to make the surfactant-polymer solution stable at the desired salinity. This study focuses on contrasting the effect of addition of a co-solvent in stability of a surfactant –oil emulsion. The idea is to use a co-surfactant to increase stability of an emulsion. Stability of the emulsion is enhanced because of creation of micro-emulsion which is verified both visually and with the help of particle size analyzer at varying concentration of salinity, surfactant and co-surfactant. A lab-experimental method description is provided and the method is described in detail to permit readers to emulate all results. The stability of the oil-water emulsion is visualized with respect to time, temperature, salinity of the brine and concentration of the surfactant. Nonionic surfactant TX-100 when used as a co-surfactant increases the stability of the oil-water emulsion. The stability of the prepared emulsion is checked by observing the particle size distribution. For stable emulsion in volume% vs particle size curve, the peak should be obtained for particle size of 5-50 nm while for the unstable emulsion a bigger sized particles are observed. The UV-Visible spectroscopy is also used to visualize the fraction of oil that plays important role in the formation of micelles in stable emulsion. This is important as the study will help us to decide applicability of the surfactant based EOR method for a reservoir that contains a specific type of crude. The use of nonionic surfactant as a co-surfactant would also increase the efficiency of surfactant EOR. With the decline in oil discoveries during the last decades it is believed that EOR technologies will play a key role to meet the energy demand in years to come. Taking this into consideration, the work focuses on the optimization of the secondary recovery(Water flooding) with the help of surfactant and/or co-surfactants by creating desired conditions in the reservoir.

Keywords: co-surfactant, enhanced oil recovery, micro-emulsion, surfactant flooding

Procedia PDF Downloads 241

Authors: Garry A. Einicke, Langford B. White

Abstract:

This paper describes an optimum filter and smoother for recovering a Markov process message from noisy measurements. The developments follow from an equivalence between a state space model and a hidden Markov chain. The ensuing filter and smoother employ transition probability matrices and approximate probability distribution vectors. The properties of the optimum solutions are retained, namely, the estimates are unbiased and minimize the variance of the output estimation error, provided that the assumed parameter set are correct. Methods for estimating unknown parameters from noisy measurements are discussed. Signal recovery examples are described in which performance benefits are demonstrated at an increased calculation cost.

Keywords: optimal filtering, smoothing, Markov chains

Procedia PDF Downloads 308