Search results for: time dependent magnetic field intensity

Authors: Sadok Aboubakr

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The mechanical behavior of cracks from several manufacturing defect in an oil pipeline, is characterized by the fact that defects'm taking several forms: circumferential, longitudinal and inclined crack that evolve over time. Increased lifetime of the constructions and in particular cylindrical tubes under internal pressure requires knowledge improving these defects during loading. From this study we simulated various forms of cracking and also their pipeline repair patch.

Keywords: stress intensity factor, pressure, Young's modulus, Poisson's ratio, Shear modulus, Longueur du pipeline, the angle of crack, crack length

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Authors: Vishnu A., Ashesh Saha

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The operation of high-speed rotating machinery in industries is accompanied by rotor vibrations due to many factors. One of the primary instability mechanisms in a rotor system is the centrifugal force induced due to the eccentricity of the center of mass away from the center of rotation. These unwanted vibrations may lead to catastrophic fatigue failure. So, there is a need to control these rotor vibrations. In this work, control of rotor vibrations by using a 4-pole Radial Active Magnetic Bearing (RAMB) as an actuator is analysed. A continuous rotor system model is considered for the analysis. Several important factors, like the gyroscopic effect and rotary inertia of the shaft and disc, are incorporated into this model. The large deflection of the shaft and the restriction to axial motion of the shaft at the bearings result in nonlinearities in the system governing equation. The rotor system is modeled in such a way that the system dynamics can be related to the geometric and material properties of the shaft and disc. The mathematical model of the rotor system is developed by incorporating the control forces generated by the RAMB. A simple PD controller is used for the attenuation of system vibrations. An analytical expression for the amplitude and phase equations is derived using the Method of Multiple Scales (MMS). Analytical results are verified with the numerical results obtained using an ‘ode’ solver in-built into MATLAB Software. The control force is found to be effective in attenuating the system vibrations. The multi-valued solutions leading to the jump phenomenon are also eliminated with a proper choice of control gains. Most interestingly, the shape of the backbone curves can also be altered for certain values of control parameters.

Keywords: rotor dynamics, continuous rotor system model, active magnetic bearing, PD controller, method of multiple scales, backbone curve

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Authors: Mahsa Fathollahzadeh

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The quick advancement of nanotechnology necessitates the creation of innovative theoretical approaches to elucidate complex experimental findings and forecast novel capabilities of nanodevices. Therefore, over the past ten years, a difficult task in quantum chemistry has been comprehending electron and spin transport in molecular devices. This thorough evaluation presents a comprehensive overview of current research and its status in the field of molecular electronics, emphasizing the theoretical applications to various device types and including a brief introduction to theoretical methods and their practical implementation plan. The subject matter includes a variety of molecular mechanisms like molecular cables, diodes, transistors, electrical and visual switches, nano detectors, magnetic valve gadgets, inverse electrical resistance gadgets, and electron tunneling exploration. The text discusses both the constraints of the method presented and the potential strategies to address them, with a total of 183 references.

Keywords: chemistry, nanotechnology, quantum, molecule, spin

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Authors: Sudip Kumar Kundu, Charu Singh

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The climatic condition over Indian region is highly dependent on monsoon. India receives maximum amount of rainfall during southwest monsoon. Indian economy is highly dependent on agriculture. The presence of flood and drought years influenced the total cultivation system as well as the economy of the country as Indian agricultural systems is still highly dependent on the monsoon rainfall. The present study has been planned to investigate the flood and drought years for the north-west Himalayan region from 1951 to 2014 by using area average Indian Meteorological Department (IMD) rainfall data. For this investigation the Normalized index (NI) has been utilized to find out whether the particular year is drought or flood. The data have been extracted for the north-west Himalayan (NWH) region states namely Uttarakhand (UK), Himachal Pradesh (HP) and Jammu and Kashmir (J&K) to find out the rainy season average rainfall for each year, climatological mean and the standard deviation. After calculation it has been plotted by the diagrams (or graphs) to show the results- some of the years associated with drought years, some are flood years and rest are neutral. The flood and drought years can also relate with the large-scale phenomena El-Nino and La-Lina.

Keywords: IMD, rainfall, normalized index, flood, drought, NWH

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Authors: Sreevalli Bokka

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The process of reducing the intensity of the carbon from a process or stream into the atmosphere is termed Decarbonization. Of the various technologies that are emerging to capture or reduce carbon intensity, membranes are emerging as a key player in separating carbon from a gas stream, such as industrial effluent air and others. Due to the advantage of high surface area and low flow resistance, fiber membranes are emerging widely for gas separation applications. A fiber membrane is a semipermeable barrier that is increasingly used for filtration and separation applications needing high packing density. A few of the many applications are in water desalination, medical applications, bioreactors, and gas separations applications. Only a few polymeric membranes were studied for fabricating fiber membranes such as cellulose acetate, Polysulfone, and Polyvinylidene fluoride. A few of the challenges of using fiber membranes are fouling and weak mechanical properties, leading to the breakage of membranes. In this work, the growth of fiber membranes and challenges for future developments in the filtration and gas separation applications are presented.

Keywords: membranes, filtration, separations, polymers, carbon capture

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Authors: Mohamedou El Boukhary, Farba Bouyagui Tamboura, A. Hamady Barry, T. Moussa Seck, Mohamed L. Gaye

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Nowadays, low-schiff acyl-hydrazone ligands are highly sought after due to their wide applications in various fields of biology, coordination chemistry, and catalysis. They are studied for their antioxidant, antibacterial and antiviral properties. The complexes of transition metals and the lanthanide they derive are well known for their magnetic, optical, and catalytic properties. In this work, we present the synthesis of an acyl-hydrazone (H2L) schiff base and their 3d transition complexes. The ligand (H2L) is characterized by IR, NMR (1H; 13C) spectroscopy. The complexes are characterized by different physic-chemical techniques such as IR, UV-visible, conductivity, measurement of magnetic susceptibility. The study of XRD allowed us to elucidate the crystalline structure of the manganese (Mn) complex. The asymmetric unit of the complex is composed of two molecules of the ligand, one manganese (II) ion, and two coordinate chloride ions; the environment around Mn is described as a pentagonal base bipyramid. In the crystal lattice, the asymmetric unit is bound by hydrogen bonds.

Keywords: synthene, acyl-hydrazone, 3D transition metal complex, application

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Authors: Siti Rahmah Shamsuri, Eiichiro Matsubara, Shohei Shiomi

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The 1D nanomaterial is far surpassed the 0D nanomaterial. It does not just offer most of the benefit of the 0D nanomaterial such as the large surface area, a great number of active site and an efficient interfacial charge transfer but also can assemble into free-standing and flexible electrode due to their high aspect ratio. Thus, it is essential to develop a simple and ease synthesis of this 1D nanomaterial for the practical application. Here, nickel nanowire/cellulose hybrid has been successfully fabricated via a simple liquid-phase method with the assist of the magnetic field. A finer nickel nanowire was heterogeneously nucleated on the surface of the cellulose fiber, which demonstrated the effect of the hydroxyl group on the cellulose structure. The result of the nickel nanowire size was found to vary from 66-114 nm. A detailed discussion on the mechanism of the nickel nanowire/ cellulose hybrid formation is also shown in this paper.

Keywords: cellulose nanofiber, liquid-phase reduction, metal nanowire, nano hybrid material

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Authors: Prashant G. Metri

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A numerical model is developed to study nano liquid film flow over an unsteady stretching sheet in the presence of hydromagnetic have been investigated. Similarity transformations are used to convert unsteady boundary layer equations to a system of non-linear ordinary differential equations. The resulting non-linear ordinary differential equations are solved numerically using Runge-Kutta-Fehlberg and Newton-Raphson schemes. A relationship between film thickness β and the unsteadiness parameter S is found, the effect of unsteadiness parameter S, and the hydromagnetic parameter S, on the velocity and temperature distributions are presented. The present analysis shows that the combined effect of magnetic field and viscous dissipation has a significant influence in controlling the dynamics of the considered problem. Comparison with known results for certain particular cases is in excellent agreement.

Keywords: boundary layer flow, nanoliquid, thin film, unsteady stretching sheet

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Authors: Xiaoqin Wang, Li Yin

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Background and purpose: In many practices, one estimates causal effects arising from a complex stochastic process, where a sequence of treatments are assigned to influence a certain outcome of interest, and there exist time-dependent covariates between treatments. When covariates are plentiful and/or continuous, statistical modeling is needed to reduce the huge dimensionality of the problem and allow for the estimation of causal effects. Recently, Wang and Yin (Annals of statistics, 2020) derived a new general formula, which expresses these causal effects in terms of the point effects of treatments in single-point causal inference. As a result, it is possible to conduct the modeling via point effects. The purpose of the work is to study the modeling of these causal effects via point effects. Challenges and solutions: The time-dependent covariates often have influences from earlier treatments as well as on subsequent treatments. Consequently, the standard parameters – i.e., the mean of the outcome given all treatments and covariates-- are essentially all different (null paradox). Furthermore, the dimension of the parameters is huge (curse of dimensionality). Therefore, it can be difficult to conduct the modeling in terms of standard parameters. Instead of standard parameters, we have use point effects of treatments to develop likelihood-based parametric approach to the modeling of these causal effects and are able to model the causal effects of a sequence of treatments by modeling a small number of point effects of individual treatment Achievements: We are able to conduct the modeling of the causal effects from a sequence of treatments in the familiar framework of single-point causal inference. The simulation shows that our method achieves not only an unbiased estimate for the causal effect but also the nominal level of type I error and a low level of type II error for the hypothesis testing. We have applied this method to a longitudinal study of COVID-19 mortality among Scandinavian countries and found that the Swedish approach performed far worse than the other countries' approach for COVID-19 mortality and the poor performance was largely due to its early measure during the initial period of the pandemic.

Keywords: causal effect, point effect, statistical modelling, sequential causal inference

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Authors: Engy S. El-Kayal, Mohamed M. S. Arafa

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There are various causes of ankle pain including traumatic and non-traumatic causes. Various imaging techniques are available for assessment of AP. MRI is considered to be the imaging modality of choice for ankle joint evaluation with an advantage of its high spatial resolution, multiplanar capability, hence its ability to visualize small complex anatomical structures around the ankle. However, the high costs and the relatively limited availability of MRI systems, as well as the relatively long duration of the examination all are considered disadvantages of MRI examination. Therefore there is a need for a more rapid and less expensive examination modality with good diagnostic accuracy to fulfill this gap. HRU has become increasingly important in the assessment of ankle disorders, with advantages of being fast, reliable, of low cost and readily available. US can visualize detailed anatomical structures and assess tendinous and ligamentous integrity. The aim of this study was to compare the diagnostic accuracy of HRU with MRI in the assessment of patients with AP. We included forty patients complaining of AP. All patients were subjected to real-time HRU and MRI of the affected ankle. Results of both techniques were compared to surgical and arthroscopic findings. All patients were examined according to a defined protocol that includes imaging the tendon tears or tendinitis, muscle tears, masses, or fluid collection, ligament sprain or tears, inflammation or fluid effusion within the joint or bursa, bone and cartilage lesions, erosions and osteophytes. Analysis of the results showed that the mean age of patients was 38 years. The study comprised of 24 women (60%) and 16 men (40%). The accuracy of HRU in detecting causes of AP was 85%, while the accuracy of MRI in the detection of causes of AP was 87.5%. In conclusions: HRU and MRI are two complementary tools of investigation with the former will be used as a primary tool of investigation and the latter will be used to confirm the diagnosis and the extent of the lesion especially when surgical interference is planned.

Keywords: ankle pain (AP), high-resolution ultrasound (HRU), magnetic resonance imaging (MRI) ultrasonography (US)

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Authors: Rakesh C. Mathad, G. Y. Lokesh, Basavegowda

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In agriculture using quality seeds of improved varieties is very important to ensure higher productivity thereby food security and sustainability. To ensure good productivity, seeds should have characters as described by the breeder. To know whether the characters as described by the breeder are expressing in a variety such as genuineness or genetic purity, field grow out test (GOT) is done. In pigeon pea which is long durational crop, conducting a GOT may take very long time and expensive also. Since in pigeon pea flower character is a most distinguishing character from the contaminants, conducting a field grow out test require 120-130 days or till flower emergence, which may increase cost of storage and seed production. This will also delay the distribution of seed inventory to the pigeon pea growing areas. In this view during 2014-15 with financial support of Govt. of Karnataka, India, a project to develop a molecular genetic test for newly developed variety of pigeon pea cv.TS3R was commissioned at Seed Unit, UAS, Raichur. A molecular test was developed with the help SSR markers to identify pure variety from possible off types in newly released pigeon pea variety TS3R. In the investigation, 44 primer pairs were screened to identify the specific marker associated with this variety. Pigeon pea cv. TS3R could be clearly identified by using the primer CCM 293 based on the banding pattern resolved on gel electrophoresis and PCR reactions. However some of the markers like AHSSR 46, CCM 82 and CCM 57 can be used to test other popular varieties in the region like Asha, GRG-811 and Maruti respectively. Further to develop this in to a lab test, the seed sample size was standardized to 200 seeds and a grow out matrix was developed. This matrix was used to sample 12 days old leaves to extract DNA. The lab test results were validated with actual field GOT test results and found variations within the acceptable limit of 1%. This molecular method can now be employed to test the genetic purity in pigeon pea cv TS3R which reduces the time and can be a cheaper alternative method for field GOT.

Keywords: genuineness, grow-out matrix, molecular genetic purity, SSR markers

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Authors: J. Banski

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Regardless of residence place, the type of business and the social system, an individual or groups of people use the accumulated knowledge and continuously deepen and expand its scope. Knowledge is needed by human beings to carry out certain tasks, achieve desired goals or make decisions. Knowledge is an attribute of the people of a region and is identified with the total experience and information that its residents and institutions possess, including the ability to use it. It is subject to constant development, which is the result of both the deepening and exchange of knowledge among the residents of a particular area, as well as the influx of knowledge with newly arriving residents. A good example of the aforementioned processes is in rural areas, where we are dealing with two basic groups of people between whom knowledge transfer takes place. The first group is made up of people who have lived in the village for a long time, while the second group is made up of people who migrate temporarily or permanently to the countryside. The English-language literature uses the terms oldtimers and newcomers for these groups, respectively. Newcomers, usually possessing different life experiences, cultural patterns and competencies, can be rich sources of knowledge for villagers. At the same time, the latter, with different knowledge and experience, along with knowledge of local conditions and customs, can also be an important source of knowledge for incomers to the countryside. The countryside is a particularly interesting environment for studying social interactions and the accompanying transfer of knowledge. This is because it is characterized by a high intensity of neighborly contact and a high level of trust in the private sphere. As a result of the migratory influx of new residents, the social and cultural image of the countryside is changing due to the interpenetration of urban and rural life patterns. Research on rural-urban knowledge transfer is both an opportunity to halt negative trends in the social and economic development of rural areas and support the establishment of a basis for rural renewal. This paper discusses the results of research on urban-rural knowledge transfer based on case studies carried out in a dozen villages from different regions of Poland. Their purpose was to answer three basic research questions: 1) what types of knowledge are transferred between urban and rural residents? 2) what are the main directions and intensity in knowledge transfer? And 3) what are the consequences of knowledge transfer between urban and rural residents?

Keywords: rural areas, villages, newcomers, knowledge transfer, Poland

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Authors: Taweesak Janyacharoen, Lalita Pradubgool, Lalita Wongsorn, Pitchayapa Janyacharoen

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Street dance is a form of exercise that is classified as aerobic and is very suitable for teenagers. Street dance is a dance that can create new dance moves all the time. It often incorporates elements from gymnastics and is accompanied by fast-paced music that emphasizes excitement and energy. It is a combination of high-intensity and low-intensity activities. Few studies have looked at the effects of street dance on cardiovascular endurance, and previous studies have long-term effects. However, no research study in Thailand has studied acute effects before. This study was to investigate the acute effect of street dance exercise on blood pressure, heart rate, oxygen saturation and physical fitness in sedentary subjects. Subjects were divided into 2 groups: the control group (n=15) received health education and rest, and the experimental group (n=15) received street dance exercise. Both groups will measure their blood pressure (BP), mean arterial pressure (MAP), heart rate (HR), oxygen saturation (SpO₂) and six-minute walk test (6MWT) before and after completing the program. The results found that both groups had significantly different HR when comparing before and after the program (p<0.05). MAP, HR and SpO₂ had significantly different (p<0.05) when compared between groups. This study concluded that the acute effect of street dance exercise could be increased in HR while the SpO₂ decreased. In clinical, it was seen that the values that were changed are still within the range that is considered normal. Therefore, street dance exercises can be used as one choice of alternative exercise.

Keywords: street dance, exercise, blood pressure, heart rate, oxygen saturation

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Authors: Lawrence A. Farinola

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Four point implicit schemes for the approximation of the first and pure second order derivatives for the solution of the Dirichlet problem for one dimensional Schrodinger equation with respect to the time variable t were constructed. Also, special four-point implicit difference boundary value problems are proposed for the first and pure second derivatives of the solution with respect to the spatial variable x. The Grid method is also applied to the mixed second derivative of the solution of the Linear Schrodinger time-dependent equation. It is assumed that the initial function belongs to the Holder space C⁸⁺ᵃ, 0 < α < 1, the Schrodinger wave function given in the Schrodinger equation is from the Holder space Cₓ,ₜ⁶⁺ᵃ, ³⁺ᵃ/², the boundary functions are from C⁴⁺ᵃ, and between the initial and the boundary functions the conjugation conditions of orders q = 0,1,2,3,4 are satisfied. It is proven that the solution of the proposed difference schemes converges uniformly on the grids of the order O(h²+ k) where h is the step size in x and k is the step size in time. Numerical experiments are illustrated to support the analysis made.

Keywords: approximation of derivatives, finite difference method, Schrödinger equation, uniform error

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Authors: Abdoulnabi Tavangari, Nasim Salehzadeh

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We presume a cylindrical medium that is under a uniform loading and there is a penny shaped crack located in the center of cylinder. In the crack growth analysis, the Stress Intensity Factor (SIF) is a fundamental prerequisite. In the present study, according to the RITZ method and by considering a cylindrical coordinate system as the main coordinate and a local polar coordinate, the mode-I SIF of threedimensional penny-shaped crack is obtained. In this method the unknown coefficients will be obtained with minimizing the potential energy that is including the strain energy and the external force work. By using the hook's law, stress fields will be obtained and then by using the Irvine equations, the amount of SIF will be obtained near the edge of the crack. This question has been solved for extreme medium in the Tada handbook and the result of the present research has been compared with that.

Keywords: three-dimensional cracks, penny-shaped crack, stress intensity factor, fracture mechanics, Ritz method

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Authors: Muhammad Ramzan

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A mathematical model has been envisaged to discuss three-dimensional Viscoelastic fluid flow with an effect of Cattaneo-Christov heat flux in attendance of magnetohydrodynamic (MHD). Variable thermal conductivity with the impact of homogeneous-heterogeneous reactions and convective boundary condition is also taken into account. Homotopy analysis method is engaged to obtain series solutions. Graphical illustrations depicting behaviour of sundry parameters on skin friction coefficient and all involved distributions are also given. It is observed that velocity components are decreasing functions of Viscoelastic fluid parameter. Furthermore, strength of homogeneous and heterogeneous reactions have opposite effects on concentration distribution. A comparison with a published paper has also been established and an excellent agreement is obtained; hence reliable results are being presented.

Keywords: Cattaneo Christov heat flux, homogenous-heterogeneous reactions, magnetic field, variable thermal conductivity

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Authors: Deniz Erçelen, Özlem Selcuk Bozkurt

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The course of daily human life calls for the need for memories and remembering the time and place for certain events. Recalling memories takes up a substantial amount of time for an individual. Unfortunately, scientists lack the proper technology to fully understand and observe different brain regions that interact to form or retrieve memories. The hippocampus, a complex brain structure located in the temporal lobe, plays a crucial role in memory. The hippocampus forms memories as well as allows the brain to retrieve them by ensuring that neurons fire together. This process is called “neural synchronization.” Sadly, the hippocampus is known to deteriorate often with age. Proteins and hormones, which repair and protect cells in the brain, typically decline as the age of an individual increase. With the deterioration of the hippocampus, an individual becomes more prone to memory loss. Many memory loss starts off as mild but may evolve into serious medical conditions such as dementia and Alzheimer’s disease. In their quest to fully comprehend how memories work, scientists have created many different kinds of technology that are used to examine the brain and neural pathways. For instance, Magnetic Resonance Imaging - or MRI- is used to collect detailed images of an individual's brain anatomy. In order to monitor and analyze brain functions, a different version of this machine called Functional Magnetic Resonance Imaging - or fMRI- is used. The fMRI is a neuroimaging procedure that is conducted when the target brain regions are active. It measures brain activity by detecting changes in blood flow associated with neural activity. Neurons need more oxygen when they are active. The fMRI measures the change in magnetization between blood which is oxygen-rich and oxygen-poor. This way, there is a detectable difference across brain regions, and scientists can monitor them. Electroencephalography - or EEG - is also a significant way to monitor the human brain. The EEG is more versatile and cost-efficient than an fMRI. An EEG measures electrical activity which has been generated by the numerous cortical layers of the brain. EEG allows scientists to be able to record brain processes that occur after external stimuli. EEGs have a very high temporal resolution. This quality makes it possible to measure synchronized neural activity and almost precisely track the contents of short-term memory. Science has come a long way in monitoring memories using these kinds of devices, which have resulted in the inspections of neurons and neural pathways becoming more intense and detailed.

Keywords: brain, EEG, fMRI, hippocampus, memories, neural pathways, neurons

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Authors: Ahmed Mohammed Ghaleb, Ehab Saleh Alnuzaili

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This paper attempts to generally examine Tawfiq Al-Hakim's Song of Death (1950) and John Millington Synge's Riders to the Sea (1904) by comparatively bringing the two plays under focus. Strikingly, the similarities between the two plays appear in the plot, picturization of the characters, tragic intensity, structural perfection, and the economy of language. Plot structure, albeit a simple one in both plays, is enriched by the playwrights' effective use of language, symbols, imagery, and tragic irony. Neither of the two plays has the traditional five-act structure; they are one-act plays. From a feminist point of view, the domination of female characters is observed in both plays. The female protagonists are the main focus of the two plays. Their brave characters and struggle are highly depicted. While Al-Hakim's protagonist is presented as a victim of tribal customs, Synge's protagonist is shown as a victim of nature. Both plays can be described as 'feminine tragedies' using the words of Oona Frwaley. Although the two plays appeared in totally different historical periods of time, both share considerable similarities, thematic as well as linguistic, which result in a concern to investigate them. The paper, basically, aims at asserting the commonalities between human beings and creating awareness of intercultural negotiations and connections. It attempts to bridge the cultural, intellectual, and social gap between Arab and Irish drama by exploring the common elements of the two plays. Thus, the paper presents a critical and comparative study of both plays highlighting the portrayal of the female protagonists.

Keywords: economy of language, imagery, protagonist, symbols, tragic intensity, tragic irony

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Authors: Meihua Fang, Yipan Guo, Tao Fei, Pengyu Tian

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Space plasma caused spacecraft surface charging is the major space environment hazard. Particle in cell (PIC) method can be used to simulate the interaction between space plasma and spacecraft. It was proved that surface charging level of spacecraft in Jupiter’s orbits was high for its’ electron-heavy plasma environment. In this paper, Jovian plasma environment is modeled and surface charging analysis is carried out by PIC based software Spacecraft Plasma Interaction System (SPIS). The results show that the spacecraft charging potentials exceed 1000V at 2Rj, 15Rj and 25Rj polar orbits in the dark side at worst case plasma model. Furthermore, the simulation results indicate that the large Jovian magnetic field increases the surface charging level for secondary electron gyration.

Keywords: Jupiter, PIC, space plasma, surface charging

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Authors: Su Sin Chong, Abdul Aziz Abdul Raman, Sulaiman Wadi Harun, Hamzah Arof

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Chemical Oxygen Demand (COD) plays a vital role determination of an appropriate strategy for wastewater treatment including the control of the quality of an effluent. In this study, a new sensing method was introduced for the first time and developed to investigate chemical oxygen demand (COD) using a Mach-Zehner Interferometer (MZI)-based dye sensor. The sensor is constructed by bridging two single mode fibres (SMF1 and SMF2) with a short section (~20 mm) of multimode fibre (MMF) and was formed by tapering the MMF to generate evanescent field which is sensitive to perturbation of sensing medium. When the COD concentration increase takes effect will induce changes in output intensity and effective refractive index between the microfiber and the sensing medium. The adequacy of decisions based on COD values relies on the quality of the measurements. Therefore, the dual output response can be applied to the analytical procedure enhance measurement quality. This work presents a detailed assessment of the determination of COD values in synthetic wastewaters. Detailed models of the measurement performance, including sensitivity, reversibility, stability, and uncertainty were successfully validated by proficiency tests where supported on sound and objective criteria. Comparison of the standard method with the new proposed method was also conducted. This proposed sensor is compact, reliable and feasible to investigate the COD value.

Keywords: chemical oxygen demand, environmental sensing, Mach-Zehnder interferometer sensor, online monitoring

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Authors: Angelo Thurairajah

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Sufficient ultimate deformation is necessary to demonstrate the member ductility, which is dependent on the section and the material ductility. The concrete cracking phase of softening prior to the plastic hinge formation is an essential feature as well. The nature of the overload behaviour is studied using the order of the ultimate deflection. The ultimate deflection is primarily dependent on the slenderness (span to depth ratio), the ductility of the reinforcing steel, the degree of moment redistribution, the type of loading, and the support conditions. The ultimate deflection and the degree of moment redistribution from the analytical study are in good agreement with the experimental results and the moment redistribution provisions of the Australian Standards AS3600 Concrete Structures Code.

Keywords: ductility, softening, ultimate deflection, overload behaviour, moment redistribution

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Authors: Torsten Hermanns, You Wang, Stefan Janssen, Markus Niessen, Christoph Schoeler, Ulrich Thombansen, Wolfgang Schulz

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In long pulse laser drilling of metals, it can be demonstrated that the ablation shape approaches a so-called asymptotic shape such that it changes only slightly or not at all with further irradiation. These findings are already known from ultra short pulse (USP) ablation of dielectric and semiconducting materials. The explanation for the occurrence of an asymptotic shape in long pulse drilling of metals is identified, a model for the description of the asymptotic hole shape numerically implemented, tested and clearly confirmed by comparison with experimental data. The model assumes a robust process in that way that the characteristics of the melt flow inside the arising melt film does not change qualitatively by changing the laser or processing parameters. Only robust processes are technically controllable and thus of industrial interest. The condition for a robust process is identified by a threshold for the mass flow density of the assist gas at the hole entrance which has to be exceeded. Within a robust process regime the melt flow characteristics can be captured by only one model parameter, namely the intensity threshold. In analogy to USP ablation (where it is already known for a long time that the resulting hole shape results from a threshold for the absorbed laser fluency) it is demonstrated that in the case of robust long pulse ablation the asymptotic shape forms in that way that along the whole contour the absorbed heat flux density is equal to the intensity threshold. The intensity threshold depends on the special material and radiation properties and has to be calibrated be one reference experiment. The model is implemented in a numerical simulation which is called AsymptoticDrill and requires such a few amount of resources that it can run on common desktop PCs, laptops or even smart devices. Resulting hole shapes can be calculated within seconds what depicts a clear advantage over other simulations presented in literature in the context of industrial every day usage. Against this background the software additionally is equipped with a user-friendly GUI which allows an intuitive usage. Individual parameters can be adjusted using sliders while the simulation result appears immediately in an adjacent window. A platform independent development allow a flexible usage: the operator can use the tool to adjust the process in a very convenient manner on a tablet during the developer can execute the tool in his office in order to design new processes. Furthermore, at the best knowledge of the authors AsymptoticDrill is the first simulation which allows the import of measured real beam distributions and thus calculates the asymptotic hole shape on the basis of the real state of the specific manufacturing system. In this paper the emphasis is placed on the investigation of the effect of multiple reflections on the asymptotic hole shape which gain in importance when drilling holes with large aspect ratios.

Keywords: asymptotic hole shape, intensity threshold, long pulse laser drilling, robust process

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Authors: Heshalini Rajagopal, Li Sze Chow, Raveendran Paramesran

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Magnetic Resonance Imaging (MRI) is one of the most important medical imaging modality. Subjective assessment of the image quality is regarded as the gold standard to evaluate MR images. In this study, a database of 210 MR images which contains ten reference images and 200 distorted images is presented. The reference images were distorted with four types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur and DCT compression. The 210 images were assessed by ten subjects. The subjective scores were presented in Difference Mean Opinion Score (DMOS). The DMOS values were compared with four FR-IQA metrics. We have used Pearson Linear Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) to validate the DMOS values. The high correlation values of PLCC and SROCC shows that the DMOS values are close to the objective FR-IQA metrics.

Keywords: medical resonance (MR) images, difference mean opinion score (DMOS), full reference image quality assessment (FR-IQA)

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Authors: Sheng-Po Tseng, Che-Hua Yang

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Motivation and Objective: Ultrasonic guided waves become an important tool for nondestructive evaluation of structures and components. Guided waves are used for the purpose of identifying defects or evaluating material properties in a nondestructive way. While guided waves are applied for evaluating material properties, instead of knowing the properties directly, preliminary signals such as time domain signals or frequency domain spectra are first revealed. With the measured ultrasound data, inversion calculation can be further employed to obtain the desired mechanical properties. Methods: This research is development of high speed inversion calculation technique for obtaining full-field mechanical properties from the quantitative laser ultrasound visualization system (QLUVS). The quantitative laser ultrasound visualization system (QLUVS) employs a mirror-controlled scanning pulsed laser to generate guided acoustic waves traveling in a two-dimensional target. Guided waves are detected with a piezoelectric transducer located at a fixed location. With a gyro-scanning of the generation source, the QLUVS has the advantage of fast, full-field, and quantitative inspection. Results and Discussions: This research introduces two important tools to improve the computation efficiency. Firstly, graphic procession unit (GPU) with large amount of cores are introduced. Furthermore, combining the CPU and GPU cores, parallel procession scheme is developed for the inversion of full-field mechanical properties based on the QLUVS data. The newly developed inversion scheme is applied to investigate the computation efficiency for single-layered and double-layered plate-like samples. The computation efficiency is shown to be 80 times faster than unparalleled computation scheme. Conclusions: This research demonstrates a high-speed inversion technique for the characterization of full-field material properties based on quantitative laser ultrasound visualization system. Significant computation efficiency is shown, however not reaching the limit yet. Further improvement can be reached by improving the parallel computation. Utilizing the development of the full-field mechanical property inspection technology, full-field mechanical property measured by non-destructive, high-speed and high-precision measurements can be obtained in qualitative and quantitative results. The developed high speed computation scheme is ready for applications where full-field mechanical properties are needed in a nondestructive and nearly real-time way.

Keywords: guided waves, material characterization, nondestructive evaluation, parallel processing

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Authors: Jongwan Eun, Sam Helwany, Lakshyana K. C.

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The United Arab Emirates (UAE) is significantly dependent on desalinated water and groundwater resource, which is expensive and highly energy intensive. Despite the scarce water resource, stagnates only 54% of the recycled water was reused in 2012, and due to the lack of infrastructure to reuse the recycled water, the portion is expected to decrease with growing water usage. In this study, an “Oasis” complex comprised of Sustainable Farming Compartments (SFC) was proposed for reusing treated wastewater. The wastewater is used to decrease the ambient temperature of the SFC via an evaporative cooler. The SFC prototype was designed, built, and tested in an environmentally controlled laboratory and field site to evaluate the feasibility and effectiveness of the SFC subjected to various climatic conditions in Abu Dhabi. Based on the experimental results, the temperature drop achieved in the SFC in the laboratory and field site were5 ̊C from 22 ̊C and 7- 15 ̊C (from 33-45 ̊C to average 28 ̊C at relative humidity < 50%), respectively. An energy simulation using TRNSYS was performed to extend and validate the results obtained from the experiment. The results from the energy simulation and experiments show statistically close agreement. The total power consumption of the SFC system was approximately three and a half times lower than that of an electrical air conditioner. Therefore, by using treated wastewater, the SFC has a promising prospect to solve Abu Dhabi’s ecological concern related to desertification and wind erosion.

Keywords: ecological farming system, energy simulation, evaporative cooling system, temperature, treated waste water, temperature

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Authors: Monalisa Halder, Amit K. Das, Ajit K. Meikap

Abstract:

Polymer nanocomposites are very significant materials both in academia and industry for diverse potential applicability in electronics. Polymer plays the role of matrix element which has low density, flexibility, good mechanical strength and electrical properties. Use of nanosized multiferroic filler in the polymer matrix is suitable to achieve nanocomposites with enhanced magneto-dielectric effect and good mechanical properties both at the same time. Multiferroic terbium manganate (TbMnO₃) nanoparticles have been synthesized by sol-gel method using chloride precursors. Terbium manganate-polyvinyl alcohol (TbMnO₃-PVA) nanocomposite film has been prepared by solution casting method. Crystallite size of TbMnO₃ nanoparticle has been calculated to be ~ 40 nm from XRD analysis. Morphological study of the samples has been done by scanning electron microscopy and a well dispersion of the nanoparticles in the PVA matrix has been found. Thermogravimetric analysis (TGA) exhibits enhancement of thermal stability of the nanocomposite film with the inclusion of TbMnO₃ nanofiller in PVA matrix. The electrical transport properties of the nanocomposite film sample have been studied in the frequency range 20Hz - 2MHz at and above room temperature. The frequency dependent variation of ac conductivity follows universal dielectric response (UDR) obeying Jhonscher’s sublinear power law. Correlated barrier hopping (CBH) mechanism is the dominant charge transport mechanism with maximum barrier height 19 meV above room temperature. The variation of dielectric constant of the sample with frequency has been studied at different temperatures. Real part of dielectric constant at 1 KHz frequency at room temperature of the sample is found to be ~ 8 which is higher than that of the pure PVA film sample (~ 6). Dielectric constant decreases with the increase in frequency. Relaxation peaks have been observed in the variation of imaginary part of electric modulus with frequency. The relaxation peaks shift towards higher frequency as temperature increases probably due to the existence of interfacial polarization in the sample in presence of applied electric field. The current-voltage (I-V) characteristics of the nanocomposite film have been studied under ±40 V applied at different temperatures. I-V characteristic exhibits temperature dependent rectifying nature indicating the formation of Schottky barrier diode (SBD) with barrier height 23 meV. In conclusion, using multiferroic TbMnO₃ nanofiller in PVA matrix, enhanced thermal stability and electrical properties can be achieved.

Keywords: correlated barrier hopping, nanocomposite, schottky diode, TbMnO₃, TGA

Procedia PDF Downloads 127

Authors: C. Rekha, G. N. Krishnamurthy

Abstract:

This paper attempts to develop a different approach for key scheduling algorithm which uses both Blowfish and AES algorithms. The main drawback of Blowfish algorithm is, it takes more time to create the S-box entries. To overcome this, we are replacing process of S-box creation in blowfish, by using key dependent S-box creation from AES without affecting the basic operation of blowfish. The method proposed in this paper uses good features of blowfish as well as AES and also this paper demonstrates the performance of blowfish and new algorithm by considering different aspects of security namely Encryption Quality, Key Sensitivity, and Correlation of horizontally adjacent pixels in an encrypted image.

Keywords: AES, blowfish, correlation coefficient, encryption quality, key sensitivity, s-box

Procedia PDF Downloads 226

Authors: Mojgan Zendehdel, Safura Molla Mohammad Zamani

Abstract:

In this paper, Fe3O4/NaY zeolite nanocomposite with different molar ratio were successfully synthesized and characterized using FT-IR, XRD, TGA, SEM and VSM techniques. The SEM graphs showed that much of Fe3O4 was successfully coated by the NaY zeolite layer. Also, the results show that the magnetism of the products is stable with added zeolite. The catalytic effect of nanocomposite investigated for esterification reaction under solvent-free conditions. Hence, the effect of the catalyst amount, reaction time, reaction temperature and reusability of catalyst were considered and nanocomposite that created from zeolite and 16.6 percent of Fe3O4 showed the highest yield. The catalyst can be easily separated from reaction with the magnet and it can also be used for several times.

Keywords: zeolite, magnetic, nanocompsite, esterification

Procedia PDF Downloads 461

Authors: Hossein Tavallali, Mohammad Ali Karimi, Gohar Deilamy-Rad

Abstract:

In this study, a new type of alumina-coated magnetite nanoparticles (Fe3O4/Al2O3 NPs) with sodium dodecyl sulfate- 1-(2-pyridylazo)-2-naphthol (SDS-PAN) as a new sorbent solid phase extraction (SPE) has been successfully synthesized and applied for preconcentration and separation of Cd and Pb in environmental samples. Compared with conventional SPE methods, the advantages of this new magnetic Mixed Hemimicelles Solid-Phase Extraction Procedure (MMHSPE) still include easy preparation and regeneration of sorbents, short times of sample pretreatment, high extraction yields, and high breakthrough volumes. It shows great analytical potential in preconcentration of Cd and Pb compounds from large volume water samples. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS-PAN, satisfactory concentration factor and extraction recoveries can be produced with only 0.05 g Fe3O4/Al2O3 NPs. The metals were eluted with 3mL HNO3 2 mol L-1 directly and detected with the detection system Flame Atomic Absorption Spectrometry (FAAS). Various influencing parameters on the separation and preconcentration of trace metals, such as the amount of PAN, pH value, sample volume, standing time, desorption solvent and maximal extraction volume, amount of sorbent and concentration of eluent, were studied. The detection limits of this method for Cd and Pb were 0.3 and 0.7 ng mL−1 and the R.S.D.s were 3.4 and 2.8% (C = 28.00 ng mL-1, n = 6), respectively. The preconcentration factor of the modified nanoparticles was 166.6. The proposed method has been applied to the determination of these metal ions at trace levels in soil, river, tap, mineral, spring and wastewater samples with satisfactory results.

Keywords: Alumina-coated magnetite nanoparticles, Magnetic Mixed Hemimicell Solid-Phase Extraction, Cd and Pb, soil sample

Procedia PDF Downloads 316

Authors: Elena G. Salina, Laurent R. Chiarelli, Maria R. Pasca, Vadim A. Makarov

Abstract:

Tuberculosis is one of the most challenging threats to human health, confronted by the problem of drug resistance. Evidently, new drugs for tuberculosis are urgently needed. Thienopyrimidine TP053 is one of the most promising new antitubercular prodrugs. Mycothiol-dependent reductase Mrx2, encoded by rv2466c, is known to be a TP053 activator; however, the precise mode of action of this compound remained unclear. Being highly active against both replicating and non-replicating tuberculosis bacilli, TP053 also revealed dose-escalating activity for M. tuberculosis-infected murine macrophages. The chemical structure of TP053 is characterized by the presence of NO₂ group which was suggested to be responsible for the toxic effects of the activated compound. Reduction of a nitroaromatic moiety of TP53 by Mrx2 was hypothesized to result in NO release. Analysis of the products of enzymatic activation of TP053 by Mrx2 by the Greiss reagent clearly demonstrated production of nitric oxide in a time-dependent manner. Mass-spectra of cell lysates of TP-treated M. tuberculosis bacilli demonstrated the transformation of TP053 to its non-active metabolite with Mw=261 that corresponds NO release. The mechanism of NO toxicity for bacteria includes DNA damage and degradation of iron-sulfur centers, especially under oxygen depletion. Thus, TP-053 drug-like scaffold is prospective for further development of novel anti-TB drug. This work was financially supported by the Russian Foundation for Basic Research (Grant 17-04-00342).

Keywords: drug discovery, M. tuberculosis, nitric oxide, NO donors

Procedia PDF Downloads 153