Search results for: Islamic geometry

Authors: Ila Thakur, Atul Srivastava, Shyamprasad Karagadde

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The phenomenon of double-diffusive convection is driven by density gradients created by two different components (e.g., temperature and concentration) having different molecular diffusivities. The evolution of horizontal double-diffusive layers (DDLs) is one of the outcomes of double-diffusive convection occurring in a laterally/vertically cooled rectangular cavity having a pre-existing vertically stable composition field. The present work mainly focuses on different characteristics of the formation and merging of double-diffusive layers by imposing lateral/vertical thermal gradients in a vertically stable compositional field. A CFD-based twodimensional fluent model has been developed for the investigation of the aforesaid phenomena. The configuration containing vertical thermal gradients shows the evolution and merging of DDLs, where, elements from the same horizontal plane move vertically and mix with surroundings, creating a horizontal layer. In the configuration of lateral thermal gradients, a specially oriented convective roll was found inside each DDL and each roll was driven by the competing density change due to the already existing composition field and imposed thermal field. When the thermal boundary layer near the vertical wall penetrates the salinity interface, it can disrupt the compositional interface and can lead to layer merging. Different analytical scales were quantified and compared for both configurations. Various combinations of solutal and thermal Rayleigh numbers were investigated to get three different regimes, namely; stagnant regime, layered regime and unicellular regime. For a particular solutal Rayleigh number, a layered structure can originate only for a range of thermal Rayleigh numbers. Lower thermal Rayleigh numbers correspond to a diffusion-dominated stagnant regime. Very high thermal Rayleigh corresponds to a unicellular regime with high convective mixing. Different plots identifying these three regimes, number, thickness and time of existence of DDLs have been studied and plotted. For a given solutal Rayleigh number, an increase in thermal Rayleigh number increases the width but decreases both the number and time of existence of DDLs in the fluid domain. Sudden peaks in the velocity and heat transfer coefficient have also been observed and discussed at the time of merging. The present study is expected to be useful in correlating the double-diffusive convection in many large-scale applications including oceanography, metallurgy, geology, etc. The model has also been developed for three-dimensional geometry, but the results were quite similar to that of 2-D simulations.

Keywords: double diffusive layers, natural convection, Rayleigh number, thermal gradients, compositional gradients

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Authors: Bahar Salavati Vie Le Sage, Ismaïl Ben Hariz, Flavien Viguier, Sirine Noura Kahil, Audrey Jacquin, Maxime Convert

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The ballast layer plays a key role in railroad maintenance and the geometry of the track structure. Ballast also holds the track in place as the trains roll over it. Track ballast is packed between the sleepers and on the sides of railway tracks. An imbalance in ballast volume on the tracks can lead to safety issues as well as a quick degradation of the overall quality of the railway segment. If there is a lack of ballast in the track bed during the summer, there is a risk that the rails will expand and buckle slightly due to the high temperatures. Furthermore, the knowledge of the ballast quantities that will be excavated during renewal works is important for efficient ballast management. The volume of excavated ballast per meter of track can be calculated based on excavation depth, excavation width, volume of track skeleton (sleeper and rail) and sleeper spacing. Since 2012, SNCF has been collecting 3D points cloud data covering its entire railway network by using 3D laser scanning technology (LiDAR). This vast amount of data represents a modelization of the entire railway infrastructure, allowing to conduct various simulations for maintenance purposes. This paper aims to present an automated method for ballast volume estimation based on the processing of LiDAR data. The estimation of abnormal volumes in ballast on the tracks is performed by analyzing the cross-section of the track. Further, since the amount of ballast required varies depending on the track configuration, the knowledge of the ballast profile is required. Prior to track rehabilitation, excess ballast is often present in the ballast shoulders. Based on 3D laser scans, a Digital Terrain Model (DTM) was generated and automatic extraction of the ballast profiles from this data is carried out. The surplus in ballast is then estimated by performing a comparison between this ballast profile obtained empirically, and a geometric modelization of the theoretical ballast profile thresholds as dictated by maintenance standards. Ideally, this excess should be removed prior to renewal works and recycled to optimize the output of the ballast renewal machine. Based on these parameters, an application has been developed to allow the automatic measurement of ballast profiles. We evaluated the method on a 108 kilometers segment of railroad LiDAR scans, and the results show that the proposed algorithm detects ballast surplus that amounts to values close to the total quantities of spoil ballast excavated.

Keywords: ballast, railroad, LiDAR , cloud point, track ballast, 3D point

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Authors: Ahmed Elsayed, Andrew Shea, Nicolas Kelly, John Allison

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In northern European climates, domestic space heating and hot water represents a significant proportion of total primary total primary energy use and meeting these demands from a national electricity grid network supplied by renewable energy sources provides an opportunity for a significant reduction in EU CO₂ emissions. However, in order to adapt to the intermittent nature of renewable energy generation and to avoid co-incident peak electricity usage from consumers that may exceed current capacity, the demand for heat must be decoupled from its generation. Storage of heat within the fabric of dwellings for use some hours, or days, later provides a route to complete decoupling of demand from supply and facilitates the greatly increased use of renewable energy generation into a local or national electricity network. The integration of thermal energy storage into the building fabric for retrieval at a later time requires much evaluation of the many competing thermal, physical, and practical considerations such as the profile and magnitude of heat demand, the duration of storage, charging and discharging rate, storage media, space allocation, etc. In this paper, the authors report investigations of thermal storage in building fabric using concrete material and present an evaluation of several factors that impact upon performance including heating pipe layout, heating fluid flow velocity, storage geometry, thermo-physical material properties, and also present an investigation of alternative storage materials and alternative heat transfer fluids. Reducing the heating pipe spacing from 200 mm to 100 mm enhances the stored energy by 25% and high-performance Vacuum Insulation results in heat loss flux of less than 3 W/m², compared to 22 W/m² for the more conventional EPS insulation. Dense concrete achieved the greatest storage capacity, relative to medium and light-weight alternatives, although a material thickness of 100 mm required more than 5 hours to charge fully. Layers of 25 mm and 50 mm thickness can be charged in 2 hours, or less, facilitating a fast response that could, aggregated across multiple dwellings, provide significant and valuable reduction in demand from grid-generated electricity in expected periods of high demand and potentially eliminate the need for additional new generating capacity from conventional sources such as gas, coal, or nuclear.

Keywords: fabric integrated thermal storage, FITS, demand side management, energy storage, load shifting, renewable energy integration

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Authors: Mathias U. Bonet, Pericles Pilidis, Georgios Doulgeris

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An aero-derivative marine Gas Turbine engine model is simulated to be installed as the main propulsion prime mover to power a cruise ship which is designed and routed to transport intending Muslim pilgrims for the annual hajj pilgrimage from Nigeria to the Islamic port city of Jeddah in Saudi Arabia. A performance assessment of the Gas Turbine engine has been conducted by examining the effect of varying aerodynamic and hydrodynamic conditions encountered at various geographical locations along the scheduled transit route during the voyage. The investigation focuses on the overall behavior of the Gas Turbine engine employed to power and propel the ship as it operates under ideal and adverse conditions to be encountered during calm and rough weather according to the different seasons of the year under which the voyage may be undertaken. The variation of engine performance under varying operating conditions has been considered as a very important economic issue by determining the time the speed by which the journey is completed as well as the quantity of fuel required for undertaking the voyage. The assessment also focuses on the increased resistance caused by the fouling of the submerged portion of the ship hull surface with its resultant effect on the power output of the engine as well as the overall performance of the propulsion system. Daily ambient temperature levels were obtained by accessing data from the UK Meteorological Office while the varying degree of turbulence along the transit route and according to the Beaufort scale were also obtained as major input variables of the investigation. By assuming the ship to be navigating the Atlantic Ocean and the Mediterranean Sea during winter, spring and summer seasons, the performance modeling and simulation was accomplished through the use of an integrated Gas Turbine performance simulation code known as ‘Turbomach’ along with a Matlab generated code named ‘Poseidon’, all of which have been developed at the Power and Propulsion Department of Cranfield University. As a case study, the results of the various assumptions have further revealed that the marine Gas Turbine is a reliable and available alternative to the conventional marine propulsion prime movers that have dominated the maritime industry before now. The techno-economic and environmental assessment of this type of propulsion prime mover has enabled the determination of the effect of changes in weather and sea conditions on the ship speed as well as trip time and the quantity of fuel required to be burned throughout the voyage.

Keywords: ambient temperature, hull fouling, marine gas turbine, performance, propulsion, voyage

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Authors: Ying-Chang Yu, Yuan-Lung Lo

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Building envelope design is one of the most popular design fields of architectural profession in nowadays. The main design trend of such system is to highlight the designer's aesthetic intention from the outlook of building project. Due to the trend of current façade design, the building envelope contains more and more layers of components, such as double skin façade, photovoltaic panels, solar control system, or even ornamental components. These exterior components are designed for various functional purposes. Most researchers focus on how these exterior elements should be structurally sound secured. However, not many researchers consider these elements would help to improve the performance of façade system. When the exterior elements are deployed in large scale, it creates an additional layer outside of original façade system and acts like a porous interface which would interfere with the aerodynamic of façade surface in micro-scale. A standard façade performance consists with 'water penetration, air infiltration rate, operation force, and component deflection ratio', and these key performances are majorly driven by the 'Design Wind Load' coded in local regulation. A design wind load is usually determined by the maximum wind pressure which occurs on the surface due to the geometry or location of building in extreme conditions. This research was designed to identify the air damping phenomenon of micro turbulence caused by porous exterior layer leading to surface wind load reduction for improvement of façade system performance. A series of wind tunnel test on dynamic pressure sensor array covered by various scale of porous exterior skin was conducted to verify the effect of wind pressure reduction. The testing specimens were designed to simulate the typical building with two-meter extension offsetting from building surface. Multiple porous exterior skins were prepared to replicate various opening ratio of surface which may cause different level of damping effect. This research adopted 'Pitot static tube', 'Thermal anemometers', and 'Hot film probe' to collect the data of surface dynamic pressure behind porous skin. Turbulence and distributed resistance are the two main factors of aerodynamic which would reduce the actual wind pressure. From initiative observation, the reading of surface wind pressure was effectively reduced behind porous media. In such case, an actual building envelope system may be benefited by porous skin from the reduction of surface wind pressure, which may improve the performance of envelope system consequently.

Keywords: multi-layer facade, porous media, facade performance, turbulence and distributed resistance, wind tunnel test

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Authors: Alejandro Adorjan

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Universities are motivated to understand the factor contributing to low retention of engineering undergraduates. While precollege students for engineering increases, the number of engineering graduates continues to decrease and attrition rates for engineering undergraduates remains high. Calculus 1 (C1) is the entry point of most undergraduate Engineering Science and often a prerequisite for Computing Curricula courses. Mathematics continues to be a major hurdle for engineering students and many students who drop out from engineering cite specifically Calculus as one of the most influential factors in that decision. In this context, creating course activities that increase retention and motivate students to obtain better final results is a challenge. In order to develop several competencies in our students of Software Engineering courses, Calculus 1 at Universidad ORT Uruguay focuses on developing several competencies such as capacity of synthesis, abstraction, and problem solving (based on the ACM/AIS/IEEE). Every semester we try to reflect on our practice and try to answer the following research question: What kind of teaching approach in Calculus 1 can we design to retain students and obtain better results? Since 2010, Universidad ORT Uruguay offers a six-week summer noncompulsory bridge course of preparatory math (to bridge the math gap between high school and university). Last semester was the first time the Department of Mathematics offered the course while students were enrolled in C1. Traditional lectures in this bridge course lead to just transcribe notes from blackboard. Last semester we proposed a Hands On Lab course using Geogebra (interactive geometry and Computer Algebra System (CAS) software) as a Math Driven Development Tool. Students worked in a computer laboratory class and developed most of the tasks and topics in Geogebra. As a result of this approach, several pros and cons were found. It was an excessive amount of weekly hours of mathematics for students and, as the course was non-compulsory; the attendance decreased with time. Nevertheless, this activity succeeds in improving final test results and most students expressed the pleasure of working with this methodology. This teaching technology oriented approach strengthens student math competencies needed for Calculus 1 and improves student performance, engagement, and self-confidence. It is important as a teacher to reflect on our practice, including innovative proposals with the objective of engaging students, increasing retention and obtaining better results. The high degree of motivation and engagement of participants with this methodology exceeded our initial expectations, so we plan to experiment with more groups during the summer so as to validate preliminary results.

Keywords: calculus, engineering education, PreCalculus, Summer Program

Procedia PDF Downloads 259

Authors: Tjipta Lesmana

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Terrorist attacks quickly penetrated Indonesia following the downfall of Soeharto regime in May 1998. Reform era was officially proclaimed. Indonesia turned to 'heaven state' from 'authoritarian state'. For the first time since 1966, the country experienced a full-scale freedom of expression, including freedom of the press, and heavy acknowledgement of human rights practice. Some religious extremists previously run away to neighbor countries to escape from security apparatus secretly backed home. Quickly they consolidated the power to continue their long aspiration and dream to establish 'Shariah Indonesia', Indonesia based on Khilafah ideology. Bali bombings I which shocked world community occurred on 12 October 2002 in the famous tourist district of Kuta on the Indonesian island of Bali, killing 202 people (including 88 Australians, 38 Indonesians, and people from more than 20 other nationalities). In the capital, Jakarta, successive bombings were blasted in Marriott hotel, Australian Embassy, residence of the Philippine Ambassador and stock exchange office. A 'drunken Indonesia' is far from ready to combat nationwide sudden and massive terrorist attacks. Police Detachment 88 (Densus 88) Indonesian counter-terrorism squad, was quickly formed following 2002 Bali Bombing. Anti-terrorism Provisional Act was immediately erected, as well, due to urgent need to fight terrorism. Some Bali bombings criminals were deadly executed after sentenced by the court. But a series of terrorist suicide attacks and another Bali bombings (the second one) in Bali, again, shocked world community. Terrorism network is undoubtedly spreading nationwide. Suspicion is high that they had close connection with Al Qaeda’s groups. Even 'Afghanistan alumni' and 'Syria alumni' returned to Indonesia to back up the local mujahidins in their fights to topple Indonesia constitutional government and set up Islamic state (Khilafah). Supported by massive aids from friendly nations, especially Australia and United States, Indonesia launched large scale operations to crush terrorism consisted of various radical groups such as JAD, JAS, and JAADI. Huge energy, money, and souls were dedicated. Terrorism is, however, persistently entrenched. High ranking officials from Detachment 88 squad and military intelligence believe that terrorism is still one the most deadly enemy of Indonesia.

Keywords: counter-radicalization, de-radicalization, Khalifah, Union State, Al Qaedah, ISIS

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Authors: Antoine Lauvray, Fabien Poulhaon, Pierre Michaud, Pierre Joyot, Emmanuel Duc

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Additive Friction Stir Manufacturing (AFSM) is a new industrial process that follows the emergence of friction-based processes. The AFSM process is a solid-state additive process using the energy produced by the friction at the interface between a rotating non-consumable tool and a substrate. Friction depends on various parameters like axial force, rotation speed or friction coefficient. The feeder material is a metallic rod that flows through a hole in the tool. Unlike in Friction Stir Welding (FSW) where abundant literature exists and addresses many aspects going from process implementation to characterization and modeling, there are still few research works focusing on AFSM. Therefore, there is still a lack of understanding of the physical phenomena taking place during the process. This research work aims at a better AFSM process understanding and implementation, thanks to numerical simulation and experimental validation performed on a prototype effector. Such an approach is considered a promising way for studying the influence of the process parameters and to finally identify a process window that seems relevant. The deposition of material through the AFSM process takes place in several phases. In chronological order these phases are the docking phase, the dwell time phase, the deposition phase, and the removal phase. The present work focuses on the dwell time phase that enables the temperature rise of the system composed of the tool, the filler material, and the substrate and due to pure friction. Analytic modeling of heat generation based on friction considers as main parameters the rotational speed and the contact pressure. Another parameter considered influential is the friction coefficient assumed to be variable due to the self-lubrication of the system with the rise in temperature or the materials in contact roughness smoothing over time. This study proposes, through numerical modeling followed by experimental validation, to question the influence of the various input parameters on the dwell time phase. Rotation speed, temperature, spindle torque, and axial force are the main monitored parameters during experimentations and serve as reference data for the calibration of the numerical model. This research shows that the geometry of the tool as well as fluctuations of the input parameters like axial force and rotational speed are very influential on the temperature reached and/or the time required to reach the targeted temperature. The main outcome is the prediction of a process window which is a key result for a more efficient process implementation.

Keywords: numerical model, additive manufacturing, friction, process

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Authors: Almaz R. Gazizov, Sergey S. Kharintsev, Myakzyum Kh. Salakhov

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This work deals with background signal suppression in tip-enhanced near-field optical microscopy (TENOM). The background appears because an optical signal is detected not only from the subwavelength area beneath the tip but also from a wider diffraction-limited area of laser’s waist that might contain another substance. The background can be reduced by using a taper probe with a grating on its lateral surface where an external illumination causes surface plasmon excitation. It requires the grating with parameters perfectly matched with a given incident light for effective light coupling. This work is devoted to an analysis of the light-grating coupling and a quest of grating parameters to enhance a near-field light beneath the tip apex. The aim of this work is to find the figure of merit of plasmon excitation depending on grating period and location of grating in respect to the apex. In our consideration the metallic grating on the lateral surface of the tapered plasmonic probe is illuminated by a plane wave, the electric field is perpendicular to the sample surface. Theoretical model of efficiency of plasmon excitation and propagation toward the apex is tested by fdtd-based numerical simulation. An electric field of the incident light is enhanced on the grating by every single slit due to lightning rod effect. Hence, grating causes amplitude and phase modulation of the incident field in various ways depending on geometry and material of grating. The phase-modulating grating on the probe is a sort of metasurface that provides manipulation by spatial frequencies of the incident field. The spatial frequency-dependent electric field is found from the angular spectrum decomposition. If one of the components satisfies the phase-matching condition then one can readily calculate the figure of merit of plasmon excitation, defined as a ratio of the intensities of the surface mode and the incident light. During propagation towards the apex, surface wave undergoes losses in probe material, radiation losses, and mode compression. There is an optimal location of the grating in respect to the apex. One finds the value by matching quadratic law of mode compression and the exponential law of light extinction. Finally, performed theoretical analysis and numerical simulations of plasmon excitation demonstrate that various surface waves can be effectively excited by using the overtones of a period of the grating or by phase modulation of the incident field. The gratings with such periods are easy to fabricate. Tapered probe with the grating effectively enhances and localizes the incident field at the sample.

Keywords: angular spectrum decomposition, efficiency, grating, surface plasmon, taper nanoantenna

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Authors: Abdel-Monem Sayed Mohamed

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Lake Aswan is one of the largest man-made reservoirs in the world. The reservoir began to fill in 1964 and the level rose gradually, with annual irrigation cycles, until it reached a maximum water level of 181.5 m in November 1999, with a capacity of 160 km3. The filling of such large reservoir changes the stress system either through increasing vertical compressional stress by loading and/or increased pore pressure through the decrease of the effective normal stress. The resulted effect on fault zones changes stability depending strongly on the orientation of pre-existing stress and geometry of the reservoir/fault system. The main earthquake occurred on November 14, 1981, with magnitude 5.5. This event occurred after 17 years of the reservoir began to fill, along the active part of the Kalabsha fault and located not far from the High Dam. Numerous of small earthquakes follow this earthquake and continue till now. For this reason, 13 seismograph stations (radio-telemetry network short-period seismometers) were installed around the northern part of Lake Aswan. The main purpose of the network is to monitor the earthquake activity continuously within Aswan region. The data described here are obtained from the continuous record of earthquake activity and lake-water level variation through the period from 1982 to 2015. The seismicity is concentrated in the Kalabsha area, where there is an intersection of the easterly trending Kalabsha fault with the northerly trending faults. The earthquake foci are distributed in two seismic zones, shallow and deep in the crust. Shallow events have focal depths of less than 12 km while deep events extend from 12 to 28 km. Correlation between the seismicity and the water level variation in the lake provides great suggestion to distinguish the micro-earthquakes, particularly, those in shallow seismic zone in the reservoir–triggered seismicity category. The water loading is one factor from several factors, as an activating medium in triggering earthquakes. The common factors for all cases of induced seismicity seem to be the presence of specific geological conditions, the tectonic setting and water loading. The role of the water loading is as a supplementary source of earthquake events. So, the earthquake activity in the area originated tectonically (ML ≥ 4) and the water factor works as an activating medium in triggering small earthquakes (ML ≤ 3). Study of the inducing seismicity from the water level variation in Aswan Lake is of great importance and play great roles necessity for the safety of the High Dam body and its economic resources.

Keywords: Aswan lake, Aswan seismic network, seismicity, water level variation

Procedia PDF Downloads 344

Authors: Mohammed Khalil Ur Rahman, Mohammed Alsharon, Arshad Muktar, Zahid Shaik

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Any ailment can go into terminal stages, cancer being one such disease which is many times detected in latent stages. Cancer is often characterized by constitutional symptoms which are agonizing in nature which disturbs patients and their family as well. In order to relieve such intolerable symptoms treatment modality employed is known to be ‘Palliative Care’. The goal of palliative care is to enhance patient’s quality of life by relieving or rather reducing the distressing symptoms of patients such as pain, nausea/ vomiting, anorexia/loss of appetite, excessive salivation, mouth ulcers, weight loss, constipation, oral thrush, emaciation etc. which are due to the effect of disease or due to the undergoing treatment such as chemotherapy, radiation etc. Ayurveda and Unani as well as other traditional medicines is getting more and more international attention in recent years and Ayurveda and Unani holistic perspective of the disease, it seems that there are many herbs and herbomineral preparation which can be employed in the treatment of malignancy and also in palliative care. Though many of them have yet to be scientifically proved as anti-cancerous but there is definitely a positive lead that some of these medications relieve the agonising symptoms thereby making life of the patient easy. Health is viewed in Islam in a holistic way. One of the names of the Quran is al-shifa' meaning ‘that which heals’ or ‘the restorer of health’ to refer to spiritual, intellectual, psychological, and physical health. The general aim of medical science, according to Islam, is to secure and adopt suitable measures which, with Allah’s permission, help to preserve or restore the health of the human body. Islam motivates the Physician to view the patient as one organism. The patient has physical, social, psychological, and spiritual dimensions that must be considered in synthesis with an integrated, holistic approach. Aims & Objectives: - To suggest herbs which are mentioned in Ayurveda Unani with potential palliative activity in case of Cancer patients. - Most of tibb nabawi [Prophetic Medicine] is preventive medicine and must have been divinely inspired. - Spiritual Aspects of Healing: Prayer, dua, recitation of the Quran - Remembrance of Allah play a central role.Materials & Method: Literary review of the herbs supported with experiential evidence will be discussed. Discussion: On the basis of collected data subject will be discussed in length. Conclusion: Will be presented in paper.

Keywords: palliative care, holistic, Ayurvedic and Unani traditional system of medicine, Quran, hadith

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Authors: Gamaliel Salazar, Adriana Chazaro, Oscar Madrigal

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The evolution of Unmanned Aerial Systems (UAS) has made it possible to develop new vehicles capable to perform microgravity experiments which due its cost and complexity were beyond the reach for many institutions. In this study, the aerodynamic behavior of an UAS is studied through its deceleration stage after an initial free fall phase (where the microgravity effect is generated) using Computational Fluid Dynamics (CFD). Due to the fact that the payload would be analyzed under a microgravity environment and the nature of the payload itself, the speed of the UAS must be reduced in a smoothly way. Moreover, the terminal speed of the vehicle should be low enough to preserve the integrity of the payload and vehicle during the landing stage. The UAS model is made by a study pod, control surfaces with fixed and mobile sections, landing gear and two semicircular wing sections. The speed of the vehicle is decreased by increasing the angle of attack (AoA) of each wing section from 2° (where the airfoil S1091 has its greatest aerodynamic efficiency) to 80°, creating a circular wing geometry. Drag coefficients (Cd) and forces (Fd) are obtained employing CFD analysis. A simplified 3D model of the vehicle is analyzed using Ansys Workbench 16. The distance between the object of study and the walls of the control volume is eight times the length of the vehicle. The domain is discretized using an unstructured mesh based on tetrahedral elements. The refinement of the mesh is made by defining an element size of 0.004 m in the wing and control surfaces in order to figure out the fluid behavior in the most important zones, as well as accurate approximations of the Cd. The turbulent model k-epsilon is selected to solve the governing equations of the fluids while a couple of monitors are placed in both wing and all-body vehicle to visualize the variation of the coefficients along the simulation process. Employing a statistical approximation response surface methodology the case of study is parametrized considering the AoA of the wing as the input parameter and Cd and Fd as output parameters. Based on a Central Composite Design (CCD), the Design Points (DP) are generated so the Cd and Fd for each DP could be estimated. Applying a 2nd degree polynomial approximation the drag coefficients for every AoA were determined. Using this values, the terminal speed at each position is calculated considering a specific Cd. Additionally, the distance required to reach the terminal velocity at each AoA is calculated, so the minimum distance for the entire deceleration stage without comprising the payload could be determine. The Cd max of the vehicle is 1.18, so its maximum drag will be almost like the drag generated by a parachute. This guarantees that aerodynamically the vehicle can be braked, so it could be utilized for several missions allowing repeatability of microgravity experiments.

Keywords: microgravity effect, response surface, terminal speed, unmanned system

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Authors: R. Khare, R. V. Gelamo, M. A. More, D. J. Late, Chandra Sekhar Rout

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Graphene emerges out as a promising material for various applications ranging from complementary integrated circuits to optically transparent electrode for displays and sensors. The excellent conductivity and atomic sharp edges of unique two-dimensional structure makes graphene a propitious field emitter. Graphene analogues of other 2D layered materials have emerged in material science and nanotechnology due to the enriched physics and novel enhanced properties they present. There are several advantages of using 2D nanomaterials in field emission based devices, including a thickness of only a few atomic layers, high aspect ratio (the ratio of lateral size to sheet thickness), excellent electrical properties, extraordinary mechanical strength and ease of synthesis. Furthermore, the presence of edges can enhance the tunneling probability for the electrons in layered nanomaterials similar to that seen in nanotubes. Here we report electron emission properties of multilayer graphene and effect of plasma (CO2, O2, Ar and N2) treatment. The plasma treated multilayer graphene shows an enhanced field emission behavior with a low turn on field of 0.18 V/μm and high emission current density of 1.89 mA/cm2 at an applied field of 0.35 V/μm. Further, we report the field emission studies of layered WS2/RGO and SnS2/RGO composites. The turn on field required to draw a field emission current density of 1μA/cm2 is found to be 3.5, 2.3 and 2 V/μm for WS2, RGO and the WS2/RGO composite respectively. The enhanced field emission behavior observed for the WS2/RGO nanocomposite is attributed to a high field enhancement factor of 2978, which is associated with the surface protrusions of the single-to-few layer thick sheets of the nanocomposite. The highest current density of ~800 µA/cm2 is drawn at an applied field of 4.1 V/μm from a few layers of the WS2/RGO nanocomposite. Furthermore, first-principles density functional calculations suggest that the enhanced field emission may also be due to an overlap of the electronic structures of WS2 and RGO, where graphene-like states are dumped in the region of the WS2 fundamental gap. Similarly, the turn on field required to draw an emission current density of 1µA/cm2 is significantly low (almost half the value) for the SnS2/RGO nanocomposite (2.65 V/µm) compared to pristine SnS2 (4.8 V/µm) nanosheets. The field enhancement factor β (~3200 for SnS2 and ~3700 for SnS2/RGO composite) was calculated from Fowler-Nordheim (FN) plots and indicates emission from the nanometric geometry of the emitter. The field emission current versus time plot shows overall good emission stability for the SnS2/RGO emitter. The DFT calculations reveal that the enhanced field emission properties of SnS2/RGO composites are because of a substantial lowering of work function of SnS2 when supported by graphene, which is in response to p-type doping of the graphene substrate. Graphene and 2D analogue materials emerge as a potential candidate for future field emission applications.

Keywords: graphene, layered material, field emission, plasma, doping

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Authors: Louise Reyntjens

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In response to Islamic-inspired terrorism and the growing trend of foreign fighters, European governments are increasingly relying on the deprivation of citizenship as a security tool. This development fits within a broader securitization of immigration, where the terrorist threat is perceived as emanating from abroad. As a result, immigration law became more and more ‘securitized’. The European migration crisis has reinforced this trend. This research evaluates the deprivation of citizenship from a human rights perspective. For this, the author selected four European countries for a comparative study: Belgium, France, the United Kingdom and Sweden. All these countries face similar social and security issues, vitalizing (the debate on) deprivation of citizenship as a counterterrorism tool. Yet, they adopt a very different approach on this: The United Kingdom positions itself on the repressive side of the spectrum. Sweden on the other hand, also ‘securitized’ its immigration policy after the recent terrorist hit in Stockholm but remains on the tolerant side of the spectrum. Belgium and France are situated in between. This contribution evaluates the deprivation of citizenship in Belgium. Belgian law has provided the possibility to strip someone of their Belgian citizenship since 1919. However, the provision long remained a dead letter. The 2015 Charlie Hebdo attacks in Paris sparked a series of legislative changes, elevating the deprivation measure to a key security tool in Belgian law. Yet, the measure raises profound human rights issues. Firstly, it infringes the right to private and family life. As provided by Article 8 (2) European Court of Human Right (ECHR), this right can be limited if necessary for national security and public safety. Serious questions can however be raised about the necessity for the national security of depriving an individual of its citizenship. Behavior giving rise to this measure will generally be governed by criminal law. From a security perspective, criminal detention will thus already provide in removing the individual from society. Moreover, simply stripping an individual of its citizenship and deporting them constitutes a failure of criminal law’s responsibility to prosecute criminal behavior. Deprivation of citizenship is also discriminatory, because it differentiates, without a legitimate reason, between those liable to deprivation and those who are not. It thereby installs a secondary class of citizens, violating the European Court of Human Right’s principle that no distinction can be tolerated between children on the basis of the status of their parents. If followed by expulsion, deprivation also seriously jeopardizes the right to life and prohibition of torture. This contribution explores the human rights consequences of citizenship deprivation as a security tool in Belgium. It also offers a critical view on its efficacy for protecting national security.

Keywords: Belgium, counterterrorism strategies, deprivation of citizenship, human rights, immigration law

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Authors: Tsega Asresa, Getahun Tigistu, Melaku Bayih

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Computer vision is a subfield of artificial intelligence that allows computers and systems to extract meaning from digital images and video. It is used in a wide range of fields of study, including self-driving cars, video surveillance, medical diagnosis, manufacturing, law, agriculture, quality control, health care, facial recognition, and military applications. Aromatic medicinal plants are botanical raw materials used in cosmetics, medicines, health foods, essential oils, decoration, cleaning, and other natural health products for therapeutic and Aromatic culinary purposes. These plants and their products not only serve as a valuable source of income for farmers and entrepreneurs but also going to export for valuable foreign currency exchange. In Ethiopia, there is a lack of technologies for the classification and identification of Aromatic medicinal plant parts and disease type cured by aromatic medicinal plants. Farmers, industry personnel, academicians, and pharmacists find it difficult to identify plant parts and disease types cured by plants before ingredient extraction in the laboratory. Manual plant identification is a time-consuming, labor-intensive, and lengthy process. To alleviate these challenges, few studies have been conducted in the area to address these issues. One way to overcome these problems is to develop a deep learning model for efficient identification of Aromatic medicinal plant parts with their corresponding disease type. The objective of the proposed study is to identify the aromatic medicinal plant parts and their disease type classification using computer vision technology. Therefore, this research initiated a model for the classification of aromatic medicinal plant parts and their disease type by exploring computer vision technology. Morphological characteristics are still the most important tools for the identification of plants. Leaves are the most widely used parts of plants besides roots, flowers, fruits, and latex. For this study, the researcher used RGB leaf images with a size of 128x128 x3. In this study, the researchers trained five cutting-edge models: convolutional neural network, Inception V3, Residual Neural Network, Mobile Network, and Visual Geometry Group. Those models were chosen after a comprehensive review of the best-performing models. The 80/20 percentage split is used to evaluate the model, and classification metrics are used to compare models. The pre-trained Inception V3 model outperforms well, with training and validation accuracy of 99.8% and 98.7%, respectively.

Keywords: aromatic medicinal plant, computer vision, convolutional neural network, deep learning, plant classification, residual neural network

Procedia PDF Downloads 147

Authors: Aude Gounelle, Gloria Senfaute, Ludivine Saint-Mard, Thomas Chartier

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The long-term deformation rates of faults are not fully captured by Probabilistic Seismic Hazard Assessment (PSHA). PSHA that use catalogues to develop area or smoothed-seismicity sources is limited by the data available to constraint future earthquakes activity rates. The integration of faults in PSHA can at least partially address the long-term deformation. However, careful treatment of fault sources is required, particularly, in low strain rate regions, where estimated seismic hazard levels are highly sensitive to assumptions concerning fault geometry, segmentation and slip rate. When integrating faults in PSHA various constraints on earthquake rates from geologic and seismologic data have to be satisfied. For low strain rate regions where such data is scarce it would be especially challenging. Faults in PSHA requires conversion of the geologic and seismologic data into fault geometries, slip rates and then into earthquake activity rates. Several approaches exist for translating slip rates into earthquake activity rates. In the most frequently used approach, the background earthquakes are handled using a truncated approach, in which earthquakes with a magnitude lower or equal to a threshold magnitude (Mw) occur in the background zone, with a rate defined by the rate in the earthquake catalogue. Although magnitudes higher than the threshold are located on the fault with a rate defined using the average slip rate of the fault. As high-lighted by several research, seismic events with magnitudes stronger than the selected magnitude threshold may potentially occur in the background and not only at the fault, especially in regions of slow tectonic deformation. It also has been known that several sections of a fault or several faults could rupture during a single fault-to-fault rupture. It is then essential to apply a consistent modelling procedure to allow for a large set of possible fault-to-fault ruptures to occur aleatory in the hazard model while reflecting the individual slip rate of each section of the fault. In 2019, a tool named SHERIFS (Seismic Hazard and Earthquake Rates in Fault Systems) was published. The tool is using a methodology to calculate the earthquake rates in a fault system where the slip-rate budget of each fault is conversed into rupture rates for all possible single faults and faultto-fault ruptures. The objective of this paper is to compare the SHERIFS method with one other frequently used model to analyse the impact on the seismic hazard and through sensibility studies better understand the influence of key parameters and assumptions. For this application, a simplified but realistic case study was selected, which is in an area of moderate to hight seismicity (South Est of France) and where the fault is supposed to have a low strain.

Keywords: deformation rates, faults, probabilistic seismic hazard, PSHA

Procedia PDF Downloads 36

Authors: Mardianto

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Education and learning are now grown rapidly. Synergy of techonology especially instructional technology in the learning activities are very big influence on the effectiveness of learning and creativity to achieve optimal results. But on the other hand there is a education value that is difficult to be articulated through character-forming technology such as honesty, discipline, hard work, heroism, and so forth. Learning strategy and storytelling from the past until today is still an option for teachers to convey the message of character values. With the material was loaded from the local culture (stories folklore), the combination of learning objectives (build character child) strategy, and traditional methods (storytelling and story), and the preservation of local culture (dig tale folklore) is critical to maintaining the nation's culture. In the context of maintaining the nation's culture, then since the age of the child at the level of government elementary school a necessity. Globalization, the internet and technology sometimes feel can displace the role of the teacher in the learning activities. To the oral tradition is a mainstay of storytelling should be maintained and preserved. This research was conducted at the elementary school in the city of Medan, North Sumatra Indonesia, with a random sampling technique, the 27 class teachers were respondents who were randomly assigned to the Madrasah Ibtdaiyah (Islamic Elementary School) both public and private. Research conducted at the beginning of 2014 refers to a curriculum that is being transformed in the environment ministry Republic Religion Indonesia. The results of this study indicate that; the declining skills of teachers to develop storytelling this can be seen from; 74.07% of teachers have never attended a special training storytelling, 85.19% no longer nasakah new stories, only 22.22% are teachers who incorporate methods of stories in the learning plan. Most teachers are no longer concerned with storytelling, among those experiencing difficulty in developing methods because the story; 66.67% of children are more interested in children's cartoons like Bobo boy, Angrybirds and others, 59.26 children prefer other activities than listening to a story. The teachers hope, folklore books should be preserved, storytelling training should be provided by the government through the ministry of religion, race or competition of storytelling should be scheduled, writing a new script-based populist storytelling should be provided immediately. The teachers’ hope certainly not excessive, by realizing the story method becomes articulation as the efforts of child character development based populist, therefore the local knowledge can be a strong fortress facing society in the era of progress as at present, and future.

Keywords: story telling, local wisdom, education, technology development

Procedia PDF Downloads 249

Authors: Cécile Dufloux, Klaus Böttcher, Heike Oppermann, Jürgen Wollweber

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Hexagonal aluminum nitride (AlN) is a promising candidate for several wide band gap semiconductor compound applications such as deep UV light emitting diodes (UVC LED) and fast power transistors (HEMTs). To date, bulk AlN single crystals are still commonly grown from the physical vapor transport (PVT). Single crystalline AlN wafers obtained from this process could offer suitable substrates for a defect-free growth of ultimately active AlGaN layers, however, these wafers still lack from small sizes, limited delivery quantities and high prices so far.Although there is already an increasing interest in the commercial availability of AlN wafers, comparatively cheap Si, SiC or sapphire are still predominantly used as substrate material for the deposition of active AlGaN layers. Nevertheless, due to a lattice mismatch up to 20%, the obtained material shows high defect densities and is, therefore, less suitable for high power devices as described above. Therefore, the use of AlN with specially adapted properties for optical and sensor applications could be promising for mass market products which seem to fulfill fewer requirements. To respond to the demand of suitable AlN target material for the growth of AlGaN layers, we have designed an innovative technology based on reactive plasma spraying. The goal is to produce coarse grained AlN boules with N-terminated columnar structure and high purity. In this process, aluminum is injected into a microwave stimulated nitrogen plasma. AlN, as the product of the reaction between aluminum powder and the plasma activated N2, is deposited onto the target. We used an aluminum filament as the initial material to minimize oxygen contamination during the process. The material was guided through the nitrogen plasma so that the mass turnover was 10g/h. To avoid any impurity contamination by an erosion of the electrodes, an electrode-less discharge was used for the plasma ignition. The pressure was maintained at 600-700 mbar, so the plasma reached a temperature high enough to vaporize the aluminum which subsequently was reacting with the surrounding plasma. The obtained products consist of thick polycrystalline AlN layers with a diameter of 2-3 cm. The crystallinity was determined by X-ray crystallography. The grain structure was systematically investigated by optical and scanning electron microscopy. Furthermore, we performed a Raman spectroscopy to provide evidence of stress in the layers. This paper will discuss the effects of process parameters such as microwave power and deposition geometry (specimen holder, radiation shields, ...) on the topography, crystallinity, and stress distribution of AlN.

Keywords: aluminum nitride, polycrystal, reactive plasma spraying, semiconductor

Procedia PDF Downloads 263

Authors: O. B. Iskender, K. V. Ling, V. Dubanchet, L. Simonini

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This paper discusses the recent advances and future prospects of spacecraft position and attitude control using Model Predictive Control (MPC). First, the challenges of the space missions are summarized, in particular, taking into account the errors, uncertainties, and constraints imposed by the mission, spacecraft and, onboard processing capabilities. The summary of space mission errors and uncertainties provided in categories; initial condition errors, unmodeled disturbances, sensor, and actuator errors. These previous constraints are classified into two categories: physical and geometric constraints. Last, real-time implementation capability is discussed regarding the required computation time and the impact of sensor and actuator errors based on the Hardware-In-The-Loop (HIL) experiments. The rationales behind the scenarios’ are also presented in the scope of space applications as formation flying, attitude control, rendezvous and docking, rover steering, and precision landing. The objectives of these missions are explained, and the generic constrained MPC problem formulations are summarized. Three key design elements used in MPC design: the prediction model, the constraints formulation and the objective cost function are discussed. The prediction models can be linear time invariant or time varying depending on the geometry of the orbit, whether it is circular or elliptic. The constraints can be given as linear inequalities for input or output constraints, which can be written in the same form. Moreover, the recent convexification techniques for the non-convex geometrical constraints (i.e., plume impingement, Field-of-View (FOV)) are presented in detail. Next, different objectives are provided in a mathematical framework and explained accordingly. Thirdly, because MPC implementation relies on finding in real-time the solution to constrained optimization problems, computational aspects are also examined. In particular, high-speed implementation capabilities and HIL challenges are presented towards representative space avionics. This covers an analysis of future space processors as well as the requirements of sensors and actuators on the HIL experiments outputs. The HIL tests are investigated for kinematic and dynamic tests where robotic arms and floating robots are used respectively. Eventually, the proposed algorithms and experimental setups are introduced and compared with the authors' previous work and future plans. The paper concludes with a conjecture that MPC paradigm is a promising framework at the crossroads of space applications while could be further advanced based on the challenges mentioned throughout the paper and the unaddressed gap.

Keywords: convex optimization, model predictive control, rendezvous and docking, spacecraft autonomy

Procedia PDF Downloads 88

Authors: Sabeeh Lafta Farhan, Ihsan Abbass Jasim, Sohaib Kareem Al-Mamoori

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This study addresses the subject of transformation of urban structures and how does this transformation affect the character of traditional cities, which represents the research issue. Hence, the research has aimed at studying and learning about the urban structure characteristics and morphological transformation features in the traditional cities centers, and to look for means and methods to preserve the character of those cities. Cities are not merely locations inhabited by a large number of people, they are political and legal entities, in addition to economic activities that distinguish these cities, thus, they are a complex set of institutions, and the transformation in urban environment cannot be recognized without understanding these relationships. The research presumes an existing impact of urbanization on the properties of traditional structure of the Holy City of Najaf. The research has defined urbanization as restructuring and re-planning of urban areas that have lost their functions and bringing them into social and cultural life in the city, to be able to serve economy in order to better respond to the needs of users. Sacred Cities provide the organic connection between acts of worship and dealings and reveal the mechanisms and reasons behind the regulatory nature of the sacred shrine and their role in achieving organizational assimilation of urban morphology. The research has reached a theoretical framework of the particulars of urbanization. This framework has been applied to the historic center of the old city of Najaf, where the most important findings of the research were that the visual and structural dominant presence of holy shrine of Imam Ali (peace be upon him) remains to emphasize the visual particularity, and the main role of the city, which hosts one of the most important Muslim shrines in the world, in addition to the visible golden dome rising above the skyline, and the Imam Ali Mosque the hub and the center for religious activities. Thus, in view of being a place of main importance and a symbol of religious and Islamic culture, it is very important to have the shrine of Imam Ali (AS) prevailing on all zones of re-development in the old city. Consequently, the research underlined that the distinctive and unique character of the city of Najaf did not proceed from nothing, but was achieved through the unrivaled characteristics and features possessed by the city of Najaf alone, which allowed it and enabled it to occupy this status among the Arab and Muslim cities. That is why the activities arising from the development have to enhance the historical role of the city in order to have this development as clear support, strength and further addition to the city assets and its cultural heritage, and not seeing the developmental activities crushing the city urban traditional fabric, cultural heritage and its historical specificity.

Keywords: Iraq, the city of Najaf, heritage, traditional cities, morphological transformation

Procedia PDF Downloads 289

Authors: Ramin Tafazzoli, Rahime Zamanfashami, Amir Mohagheghzadeh

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Entrepreneurship is the driving engine of countries’ economic development and has a determinant role in the economic, social and cultural improvement of the societies. Entrepreneurship and its impact on countries’ destiny, result in the planner and policy makers’ attempts to explore and extend it in various aspects. These days, all countries follow their social capital development and human resource quality improvement to achieve the strategic national objectives, economic growth, value creation, cultural dynamism, civil excellence and social solidarity, pursuing the sustainable development based on innovation, entrepreneurial technology , knowledge management and knowledge-focused in various levels and areas. Because of the rapid economic and cultural changes in recent decades and also the emerged need for reinforcing the knowledge-based structures and wealth generation via knowledge, a convenient infrastructure is strongly required for generating science and technology. Devoting attention to entrepreneurship and training and fostering the students who have the essential abilities and skills for creating a suitable business unit, is one of the duties of each university. New expectations necessitate that universities in the development trend by way of entrepreneurship, play a prominent role. Since, higher education has an important role in training and fostering the specialist human resource in the society, attention to the academic entrepreneurship help to develop this issue better. The higher education, relying on its core mission (training and researching) be expected to help the path where exploit and apply the created capabilities and also to cause the development in the society. In this term, the higher education play an essential role to expanse and extent the entrepreneurial concepts by establishing the entrepreneurship universities. Therefore, it is necessary to constitute and establish the entrepreneurship university to solve the problems and improve the development trend. The entrepreneurial courses follow the objectives such as: informing, creating culture, entrepreneurial morality, technical knowledge, entrepreneurial skills transferring, preparing the audiences or researching, job creation, business establishing and its preservation. According to the vision 1404 of Islamic republic of Iran in which the society has to include the advanced knowledge in the field of technology and science generation and also economic growth. In this essay, we investigate the entrepreneurship concepts, entrepreneurship university characteristics, entrepreneurship organizations values, entrepreneurship education process, meanwhile paying attention to that fact which the university can play an essential role in entrepreneurs training by education, culture and science. At the end, we present some suggestion and some solution for obstacles, emphasizing on the vision.

Keywords: entrepreneurship, entrepreneur university, higher education, university

Procedia PDF Downloads 421

Authors: Kuheli Chakrabarty, Animesh Ghosh, Atanu Roy, Gourab Kanti Das

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Aldol reaction is an important class of carbon-carbon bond forming reactions. One of the popular ways to impose asymmetry in aldol reaction is the introduction of chiral auxiliary that binds the approaching reactants and create dissymmetry in the reaction environment, which finally evolves to enantiomeric excess in the aldol products. The last decade witnesses the usage of natural amino acids as chiral auxiliary to control the stereoselectivity in various carbon-carbon bond forming processes. In this context, L-proline was found to be an effective organocatalyst in asymmetric aldol additions. In last few decades the use of water as solvent or co-solvent in asymmetric organocatalytic reaction is increased sharply. Simple amino acids like L-proline does not catalyze asymmetric aldol reaction in aqueous medium not only that, In organic solvent medium high catalytic loading (~30 mol%) is required to achieve moderate to high asymmetric induction. In this context, huge efforts have been made to modify L-proline and 4-hydroxy-L-proline to prepare organocatalyst for aqueous medium asymmetric aldol reaction. Here, we report the result of our DFT calculations on asymmetric aldol reaction of benzaldehyde, p-NO2 benzaldehyde and t-butyraldehyde with a number of ketones using L-proline hydrazide as organocatalyst in wet solvent free condition. Gaussian 09 program package and Gauss View program were used for the present work. Geometry optimizations were performed using B3LYP hybrid functional and 6-31G(d,p) basis set. Transition structures were confirmed by hessian calculation and IRC calculation. As the reactions were carried out in solvent free condition, No solvent effect were studied theoretically. Present study has revealed for the first time, the direct involvement of two water molecules in the aldol transition structures. In the TS, the enamine and the aldehyde is connected through hydrogen bonding by the assistance of two intervening water molecules forming a supramolecular network. Formation of this type of supramolecular assembly is possible due to the presence of protonated -NH2 group in the L-proline hydrazide moiety, which is responsible for the favorable entropy contribution to the aldol reaction. It is also revealed from the present study that, water assisted TS is energetically more favorable than the TS without involving any water molecule. It can be concluded from this study that, insertion of polar group capable of hydrogen bond formation in the L-proline skeleton can lead to a favorable aldol reaction with significantly high enantiomeric excess in wet solvent free condition by reducing the activation barrier of this reaction.

Keywords: aldol reaction, DFT, organocatalysis, transition structure

Procedia PDF Downloads 405

Authors: Rima Abu Jaber Bransi, Rawya Jarjoura Burbara

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This study deals with two pioneering approaches in teaching Arabic as a mother tongue: first, computerization of literary and functional texts in the mother tongue; second, the pioneering model in teaching writing skills by computerization. The significance of the study lies in its treatment of a serious problem that is faced in the era of technology, which is the widening gap between the pupils and their mother tongue. The innovation in the study is that it introduces modern methods and tools and a pioneering instructional model that turns the process of mother tongue teaching into an effective, meaningful, interesting and motivating experience. In view of the Arabic language diglossia, standard Arabic and spoken Arabic, which constitutes a serious problem to the pupil in understanding unused words, and in order to bridge the gap between the pupils and their mother tongue, we resorted to computerized techniques; we took texts from the pre-Islamic period (Jahiliyya), starting with the Mu'allaqa of Imru' al-Qais and other selected functional texts and computerized them for teaching in an interesting way that saves time and effort, develops high thinking strategies, expands the literary good taste among the pupils, and gives the text added values that neither the book, the blackboard, the teacher nor the worksheets provide. On the other hand, we have developed a pioneering computerized model that aims to develop the pupil's ability to think, to provide his imagination with the elements of growth, invention and connection, and motivate him to be creative, and raise level of his scores and scholastic achievements. The model consists of four basic stages in teaching according to the following order: 1. The Preparatory stage, 2. The reading comprehension stage, 3. The writing stage, 4. The evaluation stage. Our lecture will introduce a detailed description of the model with illustrations and samples from the units that we built through highlighting some aspects of the uniqueness and innovation that are specific to this model and the different integrated tools and techniques that we developed. One of the most significant conclusions of this research is that teaching languages through the employment of new computerized strategies is very likely to get the Arabic speaking pupils out of the circle of passive reception into active and serious action and interaction. The study also emphasizes the argument that the computerized model of teaching can change the role of the pupil's mind from being a store of knowledge for a short time into a partner in producing knowledge and storing it in a coherent way that prevents its forgetfulness and keeping it in memory for a long period of time. Consequently, the learners also turn into partners in evaluation by expressing their views, giving their notes and observations, and application of the method of peer-teaching and learning.

Keywords: classical poetry, computerization, diglossia, writing skill

Procedia PDF Downloads 204

Authors: Dongming Feng, Fangyin Zhang, Liling Cao

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Horizontally curved steel-concrete composite box girders are extensively used in highway bridges. They consist of reinforced concrete deck on top of prefabricated steel box section beam which exhibits a high torsional rigidity to resist torsional effects induced by the curved structural geometry. This type of structural system is often constructed in two stages. The composite section will take the tension mainly by the steel box and, the compression by the concrete deck. The steel girders are delivered in large pre-fabricated U-shaped sections that are designed for ease of construction. They are then erected on site and overlaid by cast-in-place reinforced concrete deck. The functionality of the composite section is not achieved until the closed section is formed by fully cured concrete. Since this kind of composite section is built in two stages, the erection of the open steel box presents some challenges to contractors. When the reinforced concrete slab is cast-in-place, special care should be taken on bracings that can prevent the open U-shaped steel box from global and local buckling. In the case of multiple steel boxes, the design detailing should pay enough attention to the installation requirement of the bracings connecting adjacent steel boxes to prevent the global buckling. The slope in transverse direction and grade in longitudinal direction will result in some local deformation of the steel boxes that affect the connection of the bracings. During the design phase, it is common for engineers to model the curved composite box girder using one-dimensional beam elements. This is adequate to analyze the global behavior, however, it is unable to capture the local deformation which affects the installation of the field bracing connection. The presence of the local deformation may become a critical component to control the construction tolerance, and overlooking this deformation will produce inadequate structural details that eventually cause misalignment in field and erection failure. This paper will briefly describe the construction issues we encountered in real structures, investigate the difference between beam element modeling and shell/solid element modeling, and their impact on the different construction stages. P-delta effect due to the slope and curvature of the composite box girder is analyzed, and the secondary deformation is compared to the first-order response and evaluated for its impact on installation of lateral bracings. The paper will discuss the rational approach to prepare construction documents and recommendations are made on the communications between engineers, erectors, and fabricators to smooth out construction process.

Keywords: buckling, curved composite box girder, stage construction, structural detailing

Procedia PDF Downloads 103

Authors: Ibrahim Rassoul, A. Serir, E-K. Si Ahmed, J. Legrand

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The acronym PEM refers to Proton Exchange Membrane or alternatively Polymer Electrolyte Membrane. Due to its high efficiency, low operating temperature (30–80 °C), and rapid evolution over the past decade, PEMFCs are increasingly emerging as a viable alternative clean power source for automobile and stationary applications. Before PEMFCs can be employed to power automobiles and homes, several key technical challenges must be properly addressed. One technical challenge is elucidating the mechanisms underlying water transport in and removal from PEMFCs. On one hand, sufficient water is needed in the polymer electrolyte membrane or PEM to maintain sufficiently high proton conductivity. On the other hand, too much liquid water present in the cathode can cause “flooding” (that is, pore space is filled with excessive liquid water) and hinder the transport of the oxygen reactant from the gas flow channel (GFC) to the three-phase reaction sites. The experimental transparent fuel cell used in this work was designed to represent actual full scale of fuel cell geometry. According to the operating conditions, a number of flow regimes may appear in the microchannel: droplet flow, blockage water liquid bridge /plug (concave and convex forms), slug/plug flow and film flow. Some of flow patterns are new, while others have been already observed in PEMFC microchannels. An algorithm in MATLAB was developed to automatically determine the flow structure (e.g. slug, droplet, plug, and film) of detected liquid water in the test microchannels and yield information pertaining to the distribution of water among the different flow structures. A video processing algorithm was developed to automatically detect dynamic and static liquid water present in the gas channels and generate relevant quantitative information. The potential benefit of this software allows the user to obtain a more precise and systematic way to obtain measurements from images of small objects. The void fractions are also determined based on images analysis. The aim of this work is to provide a comprehensive characterization of two-phase flow in an operating fuel cell which can be used towards the optimization of water management and informs design guidelines for gas delivery microchannels for fuel cells and its essential in the design and control of diverse applications. The approach will combine numerical modeling with experimental visualization and measurements.

Keywords: polymer electrolyte fuel cell, air-water two phase flow, gas diffusion layer, microchannels, advancing contact angle, receding contact angle, void fraction, surface tension, image processing

Procedia PDF Downloads 283

Authors: Dragan Ribarić

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We employ the so-called problem-dependent linked interpolation concept to develop two cubic 4-node quadrilateral Mindlin plate finite elements with 12 external degrees of freedom. In the problem-independent linked interpolation, the interpolation functions are independent of any problem material parameters and the rotation fields are not expressed in terms of the nodal displacement parameters. On the contrary, in the problem-dependent linked interpolation, the interpolation functions depend on the material parameters and the rotation fields are expressed in terms of the nodal displacement parameters. Two cubic 4-node quadrilateral plate elements are presented, named Q4-U3 and Q4-U3R5. The first one is modelled with one displacement and two rotation degrees of freedom in every of the four element nodes and the second element has five additional internal degrees of freedom to get polynomial completeness of the cubic form and which can be statically condensed within the element. Both elements are able to pass the constant-bending patch test exactly as well as the non-zero constant-shear patch test on the oriented regular mesh geometry in the case of cylindrical bending. In any mesh shape, the elements have the correct rank and only the three eigenvalues, corresponding to the solid body motions are zero. There are no additional spurious zero modes responsible for instability of the finite element models. In comparison with the problem-independent cubic linked interpolation implemented in Q9-U3, the nine-node plate element, significantly less degrees of freedom are employed in the model while retaining the interpolation conformity between adjacent elements. The presented elements are also compared to the existing problem-independent quadratic linked-interpolation element Q4-U2 and to the other known elements that also use the quadratic or the cubic linked interpolation, by testing them on several benchmark examples. Simple functional upgrading from the quadratic to the cubic linked interpolation, implemented in Q4-U3 element, showed no significant improvement compared to the quadratic linked form of the Q4-U2 element. Only when the additional bubble terms are incorporated in the displacement and rotation function fields, which complete the full cubic linked interpolation form, qualitative improvement is fulfilled in the Q4-U3R5 element. Nevertheless, the locking problem exists even for the both presented elements, like in all pure displacement elements when applied to very thin plates modelled by coarse meshes. But good and even slightly better performance can be noticed for the Q4-U3R5 element when compared with elements from the literature, if the model meshes are moderately dense and the plate thickness not extremely thin. In some cases, it is comparable to or even better than Q9-U3 element which has as many as 12 more external degrees of freedom. A significant improvement can be noticed in particular when modeling very skew plates and models with singularities in the stress fields as well as circular plates with distorted meshes.

Keywords: Mindlin plate theory, problem-independent linked interpolation, problem-dependent interpolation, quadrilateral displacement-based plate finite elements

Procedia PDF Downloads 287

Authors: Raja Lahiani

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'Locksley Hall' is a poem that Lord Alfred Tennyson (1809-1892) published in 1842. It is believed to be his first attempt to face as a poet some of the most painful of his experiences, as it is a study of his rising out of sickness into health, conquering his selfish sorrow by faith and hope. So far, in Victorian scholarship as in modern criticism, 'Locksley Hall' has been studied and approached as a canonical Victorian English poem. The aim of this project is to prove that some strategies of translation were used in this poem in such a way as to guarantee its assimilation into the English canon and hence efface to a large extent its Arabic roots. In its relationship with its source text, 'Locksley Hall' is at the same time mimetic and imitative. As part of the terminology used in translation studies, ‘imitation’ means almost the exact opposite of what it means in ordinary English. By adopting an imitative procedure, a translator would do something totally different from the original author, wandering far and freely from the words and sense of the original text. An imitation is thus aimed at an audience which wants the work of the particular translator rather than the work of the original poet. Hallam Tennyson, the poet’s biographer, asserts that 'Locksley Hall' is a simple invention of place, incidents, and people, though he notes that he remembers the poet claiming that Sir William Jones’ prose translation of the Mu‘allaqat (pre-Islamic poems) gave him the idea of the poem. A comparative work would prove that 'Locksley Hall' mirrors a great deal of Tennyson’s biography and hence is not a simple invention of details as asserted by his biographer. It would be challenging to prove that 'Locksley Hall' shares so many details with the Mu‘allaqat, as declared by Tennyson himself, that it needs to be studied as an imitation of the Mu‘allaqat of Imru’ al-Qays and ‘Antara in addition to its being a poem in its own right. Thus, the main aim of this work is to unveil the imitative and mimetic strategies used by Tennyson in his composition of 'Locksley Hall.' It is equally important that this project researches the acculturating assimilative tools used by the poet to root his poem in its Victorian English literary, cultural and spatiotemporal settings. This work adopts a comparative methodology. Comparison is done at different levels. The poem will be contextualized in its Victorian English literary framework. Alien details related to structure, socio-spatial setting, imagery and sound effects shall be compared to Arabic poems from the Mu‘allaqat collection. This would determine whether the poem is a translation, an adaption, an imitation or a genuine work. The ultimate objective of the project is to unveil in this canonical poem a new dimension that has for long been either marginalized or ignored. By proving that 'Locksley Hall' is an imitation of classical Arabic poetry, the project aspires to consolidate its literary value and open up new gates of accessing it.

Keywords: comparative literature, imitation, Locksley Hall, Lord Alfred Tennyson, translation, Victorian poetry

Procedia PDF Downloads 180

Authors: Nejoud Alostad, Anup Bora, Prashant Dhote

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Kuwait Oil Company (KOC) has been producing from its major reservoirs that are well defined and highly productive and of superior reservoir quality. These reservoirs are maturing and priority is shifting towards difficult reservoir to meet future production requirements. This paper discusses the results of the detailed integrated study for one of the satellite complex field discovered in the early 1960s. Following acquisition of new 3D seismic data in 1998 and re-processing work in the year 2006, an integrated G&G study was undertaken to review Lower Cretaceous prospectivity of this reservoir. Nine wells have been drilled in the area, till date with only three wells showing hydrocarbons in two formations. The average oil density is around 300API (American Petroleum Institute), and average porosity and water saturation of the reservoir is about 23% and 26%, respectively. The area is dissected by a number of NW-SE trending faults. Structurally, the area consists of horsts and grabens bounded by these faults and hence compartmentalized. The Wara/Burgan formation consists of discrete, dirty sands with clean channel sand complexes. There is a dramatic change in Upper Wara distributary channel facies, and reservoir quality of Wara and Burgan section varies with change of facies over the area. So predicting reservoir facies and its quality out of sparse well data is a major challenge for delineating the prospective area. To characterize the reservoir of Wara/Burgan formation, an integrated workflow involving seismic, well, petro-physical, reservoir and production engineering data has been used. Porosity and water saturation models are prepared and analyzed to predict reservoir quality of Wara and Burgan 3rd sand upper reservoirs. Subsequently, boundary conditions are defined for reservoir and non-reservoir facies by integrating facies, porosity and water saturation. Based on the detailed analyses of volumetric parameters, potential volumes of stock-tank oil initially in place (STOIIP) and gas initially in place (GIIP) were documented after running several probablistic sensitivity analysis using Montecalro simulation method. Sensitivity analysis on probabilistic models of reservoir horizons, petro-physical properties, and oil-water contacts and their effect on reserve clearly shows some alteration in the reservoir geometry. All these parameters have significant effect on the oil in place. This study has helped to identify uncertainty and risks of this prospect particularly and company is planning to develop this area with drilling of new wells.

Keywords: original oil-in-place, sensitivity, uncertainty, sandstone, reservoir modeling, Monte-Carlo simulation

Procedia PDF Downloads 174

Authors: Lisa Kasmer

Abstract:

Teachers’ instructional decisions shape the structure and content of mathematics lessons and influence the mathematics that students are given the opportunity to learn. Therefore, it is important to better understand how teachers make instructional decisions and thus find new ways to help practicing and future teachers give their students a more effective and robust learning experience. Understanding the relationship between teachers’ instructional decisions and their goals, resources, and orientations (beliefs) is important given the heightened focus on geometric transformations in the middle school mathematics curriculum. This work is significant as the development and support of current and future teachers need more effective ways to teach geometry to their students. The following research questions frame this study: (1) As middle school mathematics teachers plan and enact instruction related to teaching transformations, what thinking processes do they engage in to make decisions about teaching transformations with or without a coordinate system and (2) How do the goals, resources and orientations of these teachers impact their instructional decisions and reveal about their understanding of teaching transformations? Teachers and students alike struggle with understanding transformations; many teachers skip or hurriedly teach transformations at the end of the school year. However, transformations are an important mathematical topic as this topic supports students’ understanding of geometric and spatial reasoning. Geometric transformations are a foundational concept in mathematics, not only for understanding congruence and similarity but for proofs, algebraic functions, and calculus etc. Geometric transformations also underpin the secondary mathematics curriculum, as features of transformations transfer to other areas of mathematics. Teachers’ instructional decisions in terms of goals, orientations, and resources that support these instructional decisions were analyzed using open-coding. Open-coding is recognized as an initial first step in qualitative analysis, where comparisons are made, and preliminary categories are considered. Initial codes and categories from current research on teachers’ thinking processes that are related to the decisions they make while planning and reflecting on the lessons were also noted. Surfacing ideas and additional themes common across teachers while seeking patterns, were compared and analyzed. Finally, attributes of teachers’ goals, orientations and resources were identified in order to begin to build a picture of the reasoning behind their instructional decisions. These categories became the basis for the organization and conceptualization of the data. Preliminary results suggest that teachers often rely on their own orientations about teaching geometric transformations. These beliefs are underpinned by the teachers’ own mathematical knowledge related to teaching transformations. When a teacher does not have a robust understanding of transformations, they are limited by this lack of knowledge. These shortcomings impact students’ opportunities to learn, and thus disadvantage their own understanding of transformations. Teachers’ goals are also limited by their paucity of knowledge regarding transformations, as these goals do not fully represent the range of comprehension a teacher needs to teach this topic well.

Keywords: coordinate plane, geometric transformations, instructional decisions, middle school mathematics

Procedia PDF Downloads 67

Authors: B. Yaman, G. Acikbas, N. Calis Acikbas

Abstract:

Epoxy based materials have advantages in tribological applications due to their unique properties such as light weight, self-lubrication capacity and wear resistance. On the other hand, their usage is often limited by their low load bearing capacity and low thermal conductivity values. In this study, it is aimed to improve tribological and also mechanical properties of epoxy by reinforcing with ceramic based porcelain waste. It is well-known that the reuse or recycling of waste materials leads to reduction in production costs, ease of manufacturing, saving energy, etc. From this perspective, epoxy and epoxy matrix composites containing 60wt% porcelain waste with different particle size in the range of below 90µm and 150-250µm were fabricated, and the effect of filler particle size on the mechanical and tribological properties was investigated. The microstructural characterization was carried out by scanning electron microscopy (SEM), and phase analysis was determined by X-ray diffraction (XRD). The Archimedes principle was used to measure the density and porosity of the samples. The hardness values were measured using Shore-D hardness, and bending tests were performed. Microstructural investigations indicated that porcelain particles were homogeneously distributed and no agglomerations were encountered in the epoxy resin. Mechanical test results showed that the hardness and bending strength were increased with increasing particle size related to low porosity content and well embedding to the matrix. Tribological behavior of these composites was evaluated in terms of friction, wear rates and wear mechanisms by ball-on-disk contact with dry and rotational sliding at room temperature against WC ball with a diameter of 3mm. Wear tests were carried out at room temperature (23–25°C) with a humidity of 40 ± 5% under dry-sliding conditions. The contact radius of cycles was set to 5 mm at linear speed of 30 cm/s for the geometry used in this study. In all the experiments, 3N of constant test load was applied at a frequency of 8 Hz and prolonged to 400m wear distance. The friction coefficient of samples was recorded online by the variation in the tangential force. The steady-state CoFs were changed in between 0,29-0,32. The dimensions of the wear tracks (depth and width) were measured as two-dimensional profiles by a stylus profilometer. The wear volumes were calculated by integrating these 2D surface areas over the diameter. Specific wear rates were computed by dividing the wear volume by the applied load and sliding distance. According to the experimental results, the use of porcelain waste in the fabrication of epoxy resin composites can be suggested to be potential materials due to allowing improved mechanical and tribological properties and also providing reduction in production cost.

Keywords: epoxy composites, mechanical properties, porcelain waste, tribological properties

Procedia PDF Downloads 179