Search results for: tension cracks
241 A Comparative Study of Public and Private School Adolescent Girls on the Issues of Menstrual Hygiene and the Management Issues
Authors: Ashok Pandey, Rajan Adhikari
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Introduction: Menstruation is part of the female reproductive cycle that starts when girls become sexually mature at the time of puberty. It is a phenomenon unique to the females. During a menstrual period, a woman bleeds from her uterus via the vagina. For decades, in many countries, academic school ‘type,’ private or public, as a predictor of or factor in future academic success has been researched and debated. MATERIAL AND METHODS: The comparative study was carried out with adolescent girls studying in both public and private schools of Kathmandu valley. A total of 100 girls participated in the survey, and out of them 21 participated in the FGD and 5 in the in- depth interview. Quantitative data from the survey was analyzed using SPSS 16.0 software. Informed verbal consent with the respective head of school and the respondents were taken before data collection. Results:The age of the respondents ranges from 11 to 18 years, with mean age of menarche being 12.37 years in both school adolescent girls. 70 percent of the public school adolescent girls and 72 percent of the private school adolescent girls are feeling upset and tension during menarche. There is a statistically significant difference on take rest during the period and good hygienic practice during menstruation of public/private school, at α=0. 05 level of significance. There is a statistically significant difference on overall score of practice during menstruation between public and private adolescent girls. Conclusion: Private schools children are more knowledgeable and maintain hygiene as compere to public school even though, it can be said that among the adolescent school girls both in public and private school, menstrual knowledge and perceptions are poor and practices often not optimal for proper hygiene. Often ignored issues of privacy affect the hygienic practices and daily lives.Keywords: Comparison, Menstruation, Private school, Public School
Procedia PDF Downloads 433240 Polarization of Lithuanian Society on Issues Related to Language Politics
Authors: Eglė Žurauskaitė, Eglė Gudavičienė
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The goal of this paper is to reveal how polarization is constructed through the use of impoliteness strategies. In general, media helps to spread various ideas very fast, and it means that processes of polarization are best revealed in computer-mediated communication (CMC) contexts. For this reason, data for the research was collected from online texts about a current, very diverse topic in Lithuania - Lithuanian language policy and regulations, because this topic is causing a lot of tension in Lithuanian society. Computer-mediated communication allows users to edit their message before they send it. It means that addressees carefully select verbal expressions to convey their message. In other words, each impoliteness strategy and its verbal expression were created intentionally. Impoliteness strategies in this research are understood as various ways to reach a communicative goal: belittle the other. To reach the goal, the public opinions of various Lithuanian public figures (e. g., cultural people, politicians, officials) were collected from new portals in 2019–2023 and analyzed using both quantitative and qualitative approaches. First, problematic aspects of the language policy, for which public figures complain, were identified. Then instances when public figures take a defensive position were analyzed: how they express this position and what it reveals about Lithuanian culture. Findings of this research demonstrate how concepts of impoliteness theory can be applied in analyzing the process of polarization in Lithuanian society on issues related to the State language policy. Also, to reveal how polarization is constructed, these tasks were set: a) determine which impoliteness strategies are used throughout the process of creating polarization, b) analyze how they were expressed verbally (e. g., as an advice, offer, etc.).Keywords: impoliteness, Lithuanian language policy, polarization, impoliteness strategies
Procedia PDF Downloads 51239 Unveiling Subconscious Autopoietic Reflexive Feedback Mechanisms of Second Order Governance from the Narration of Cognitive Autobiography of an ICT Lab during the Digital Revolution
Authors: Gianni Jacucci
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We present a retrospective on the development of a research group over the past 30+ years. We reflect on a change in observing the experience (1990-2024) of a university sociotechnical research group dedicated to instill change for innovation in client organisations and enterprises. Its cognitive and action trajectory is influenced by subjective factors: intention and interpretation. Continuity and change are both present: the trajectory of the group exhibits the dynamic interplay of two components of subjectivity, a change of focus in persistence of scheme, and a tension between stability and change. The paper illustrates the meanings the group gave to their practice while laying down mission-critical theoretical considerations – autopoiesis-. The aim of the work is to experience a fragment of phenomenological understanding (PU) of the cognitive dynamics of an STS-aware ICT uptake Laboratory during the digital revolution. PU is an intuitive going along the meaning, while staying close and present to the total situation of the phenomenon. Reading the codes that we observers invent in order to codify what nature is about, thus unveiling subconscious, autopoietic, reflexive feedback mechanisms of second order governance from work published over three decades by the ICT Lab, as if it were the narration of its cognitive autobiography. The paper brings points of discussion and insights of relevance for the STS community. It could be helpful in understanding the history of the community and in providing a platform for discussions on future developments. It can also serve as an inspiration and a historical capture for those entering the field.Keywords: phenomenology, subjectivity, autopoiesis, interpretation schemes, change for innovation, socio technical research, social study of information systems
Procedia PDF Downloads 11238 Application of Continuum Damage Concept to Simulation of the Interaction between Hydraulic Fractures and Natural Fractures
Authors: Anny Zambrano, German Gonzalez, Yair Quintero
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The continuum damage concept is used to study the interaction between hydraulic fractures and natural fractures, the objective is representing the path and relation among this two fractures types and predict its complex behavior without the need to pre-define their direction as occurs in other finite element applications, providing results more consistent with the physical behavior of the phenomenon. The approach uses finite element simulations through Abaqus software to model damage fracturing, the fracturing process by damage propagation in a rock. The modeling the phenomenon develops in two dimensional (2D) so that the fracture will be represented by a line and the crack front by a point. It considers nonlinear constitutive behavior, finite strain, time-dependent deformation, complex boundary conditions, strain hardening and softening, and strain based damage evolution in compression and tension. The complete governing equations are provided and the method is described in detail to permit readers to replicate all results. The model is compared to models that are published and available. Comparisons are focused in five interactions between natural fractures (NF) and hydraulic fractures: Fractured arrested at NF, crossing NF with or without offset, branching at intersecting NFs, branching at end of NF and NF dilation due to shear slippage. The most significant new finding is, that is not necessary to use pre-defined addresses propagation and stress condition can be evaluated as a dominant factor in the process. This is important because it can model in a more real way the generated complex hydraulic fractures, and be a valuable tool to predict potential problems and different geometries of the fracture network in the process of fracturing due to fluid injection.Keywords: continuum damage, hydraulic fractures, natural fractures, complex fracture network, stiffness
Procedia PDF Downloads 328237 An Analysis of the Wheat Export Performance of Ukraine in Europe
Authors: Kiran Bala Das
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This paper examines the Ukraine wheat export condition after Russian-Ukrainian military confrontation. The political conflict in Ukraine and the recent military intervention of Russia in Crimea is raising concern full effect of the events there is still uncertain, but some hints can be seen in the wheat market by analyzing the trend and pattern of Ukraine wheat export. Crimea is extremely important as it is where most of Ukraine grain exported by ship from its ports of the black sea. Ukraine is again seeking to establish itself a significant exporter of agricultural product with its rich black soil, it is chornozem the top soil layer that makes the country soil so fertile and become one of the major exporter of wheat in the world, its generous supplier of wheat make Ukraine 'Bread basket of Europe'. Ukraine possesses 30% of the world’s richest black soil; its agricultural industry has huge potential especially in grains. European Union (EU) is a significant trading partner of Ukraine but geopolitical tension adversely affects the wheat trade from black sea, which threatens Europe breadbasket. This study also highlights an index of export intensity to analyze the intensity of existing trade for the period 2011-2014 between Ukraine and EU countries. The result show export has intensified over the years, but this year low trade intensity. The overall consequence is hard to determine but if the situation deteriorates and Ukraine cutoff export, international wheat price will hike and grain prices (wheat) also come under the current circumstances and the recent development indicates how the grain market get affected and Agri future now in danger in Ukraine, and its forecast that Ukraine harvest low wheat crop this year and projected decline in export of wheat.Keywords: breadbasket of Europe, export intensity index, growth rate, wheat export
Procedia PDF Downloads 345236 6 DOF Cable-Driven Haptic Robot for Rendering High Axial Force with Low Off-Axis Impedance
Authors: Naghmeh Zamani, Ashkan Pourkand, David Grow
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This paper presents the design and mechanical model of a hybrid impedance/admittance haptic device optimized for applications, like bone drilling, spinal awl probe use, and other surgical techniques were high force is required in the tool-axial direction, and low impedance is needed in all other directions. The performance levels required cannot be satisfied by existing, off-the-shelf haptic devices. This design may allow critical improvements in simulator fidelity for surgery training. The device consists primarily of two low-mass (carbon fiber) plates with a rod passing through them. Collectively, the device provides 6 DOF. The rod slides through a bushing in the top plate and it is connected to the bottom plate with a universal joint, constrained to move in only 2 DOF, allowing axial torque display the user’s hand. The two parallel plates are actuated and located by means of four cables pulled by motors. The forward kinematic equations are derived to ensure that the plates orientation remains constant. The corresponding equations are solved using the Newton-Raphson method. The static force/torque equations are also presented. Finally, we present the predicted distribution of location error, cables velocity, cable tension, force and torque for the device. These results and preliminary hardware fabrication indicate that this design may provide a revolutionary approach for haptic display of many surgical procedures by means of an architecture that allows arbitrary workspace scaling. Scaling of the height and width can be scaled arbitrarily.Keywords: cable direct driven robot, haptics, parallel plates, bone drilling
Procedia PDF Downloads 255235 Water-Controlled Fracturing with Fuzzy-Ball Fluid in Tight Gas Reservoirs of Deep Coal Measures in Sulige
Authors: Xiangchun Wang, Lihui Zheng, Maozong Gan, Peng Zhang, Tong Wu, An Chang
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The deep coal measure tight gas reservoir in Sulige is usually reformed by fracturing, because the reservoir thickness is small, the water layers can be easily communicated during fracturing, which will lead to water production of gas wells and lower production of gas wells. Therefore, it is necessary to control water during fracturing in deep coal measure tight gas reservoir. Using fuzzy-ball fluid to control water fracturing can not only increase the output but also reduce the water output. The fuzzy-ball fluid was prepared indoors to carry out evaluation experiments. The fuzzy ball fluid was mixed in equal volume with the pre-fluid and formation water to test its compatibility. The core displacement device was used to test the gas and water breaking through the matrix and fractured cores blocked by fuzzy-ball fluid. The breakthrough pressure of the plunger tests its water blocking performance. The experimental results show that there is no precipitation after the fuzzy-ball fluid is mixed with the pad fluid and the formation water, respectively. The breakthrough pressure gradients of gas and water after the fuzzy-ball fluid plugged the cracks were 0.02MPa/cm and 0.04MPa/cm, respectively, and the breakthrough pressure gradients of gas and water after the matrix was plugged were 0.03MPa/cm and 0.2MPa/cm, respectively, which meet the requirements of field operation. Two wells A and B in the Sulige Gas Field were used on site to implement water control fracturing. After the pre-fluid was injected into the two wells, 50m3 of fuzzy-ball fluid was pumped to plug the water. The construction went smoothly. After water control and fracturing, the average daily output in 161 days was increased by 13.71% and 6.99% compared with that of adjacent wells in the same layer. The adjacent wells were bubbled for 3 times and 63 times respectively, while there was no effusion in A and B construction wells. The results show that fuzzy-ball fluid is a water plugging material suitable for water control fracturing in tight gas wells, and its water control mechanism can also provide a new idea for the development of water control fracturing materials.Keywords: coal seam, deep layer, fracking, fuzzy-ball fluid, reservoir reconstruction
Procedia PDF Downloads 217234 Experimental and Numerical Studies of Droplet Formation
Authors: Khaled Al-Badani, James Ren, Lisa Li, David Allanson
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Droplet formation is an important process in many engineering systems and manufacturing procedures, which includes welding, biotechnologies, 3D printing, biochemical, biomedical fields and many more. The volume and the characteristics of droplet formation are generally depended on various material properties, microfluidics and fluid mechanics considerations. Hence, a detailed investigation of this process, with the aid of numerical computational tools, are essential for future design optimization and process controls of many engineering systems. This will also improve the understanding of changes in the properties and the structures of materials, during the formation of the droplet, which is important for new material developments to achieve different functions, pending the requirements of the application. For example, the shape of the formed droplet is critical for the function of some final products, such as the welding nugget during Capacitor Discharge Welding process, or PLA 3D printing, etc. Although, most academic journals on droplet formation, focused on issued with material transfer rate, surface tension and residual stresses, the general emphasis on the characteristics of droplet shape has been overlooked. The proposed work for this project will examine theoretical methodologies, experimental techniques, and numerical modelling, using ANSYS FLUENT, to critically analyse and highlight optimization methods regarding the formation of pendant droplet. The project will also compare results from published data with experimental and numerical work, concerning the effects of key material parameters on the droplet shape. These effects include changes in heating/cooling rates, solidification/melting progression and separation/break-up times. From these tests, a set of objectives is prepared, with an intention of improving quality, stability and productivity in modelling metal welding and 3D printing.Keywords: computer modelling, droplet formation, material distortion, materials forming, welding
Procedia PDF Downloads 282233 Effect of Geometric Imperfections on the Vibration Response of Hexagonal Lattices
Authors: P. Caimmi, E. Bele, A. Abolfathi
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Lattice materials are cellular structures composed of a periodic network of beams. They offer high weight-specific mechanical properties and lend themselves to numerous weight-sensitive applications. The periodic internal structure responds to external vibrations through characteristic frequency bandgaps, making these materials suitable for the reduction of noise and vibration. However, the deviation from architectural homogeneity, due to, e.g., manufacturing imperfections, has a strong influence on the mechanical properties and vibration response of these materials. In this work, we present results on the influence of geometric imperfections on the vibration response of hexagonal lattices. Three classes of geometrical variables are used: the characteristics of the architecture (relative density, ligament length/cell size ratio), imperfection type (degree of non-periodicity, cracks, hard inclusions) and defect morphology (size, distribution). Test specimens with controlled size and distribution of imperfections are manufactured through selective laser sintering. The Frequency Response Functions (FRFs) in the form of accelerance are measured, and the modal shapes are captured through a high-speed camera. The finite element method is used to provide insights on the extension of these results to semi-infinite lattices. An updating procedure is conducted to increase the reliability of numerical simulation results compared to experimental measurements. This is achieved by updating the boundary conditions and material stiffness. Variations in FRFs of periodic structures due to changes in the relative density of the constituent unit cell are analysed. The effects of geometric imperfections on the dynamic response of periodic structures are investigated. The findings can be used to open up the opportunity for tailoring these lattice materials to achieve optimal amplitude attenuations at specific frequency ranges.Keywords: lattice architectures, geometric imperfections, vibration attenuation, experimental modal analysis
Procedia PDF Downloads 117232 The Effects of Orientation on Energy and Plasticity of Metallic Crystalline-Amorphous Interface
Authors: Ehsan Alishahi, Chuang Deng
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Commercial applications of bulk metallic glasses (BMGs) were restricted due to the sudden brittle failure mode which was the main drawback in these new class of materials. Therefore, crystalline-amorphous (C-A) composites were introduced as a toughening strategy in BMGs. In spite of numerous researches in the area of metallic C-A composites, the fundamental structure-property relation in these composites that are not exactly known yet. In this study, it is aimed to investigate the fundamental properties of crystalline-amorphous interface in a model system of Cu/CuZr by using molecular dynamics simulations. Several parameters including interface energy and mechanical properties were investigated by means of atomic models and employing Embedded Atom Method (EAM) potential function. It is found that the crystalline-amorphous interfacial energy weakly depends on the orientation of the crystalline layer, which is in stark contrast to that in a regular crystalline grain boundary. Additionally, the results showed that the interface controls the yielding of the crystalline-amorphous composites during uniaxial tension either by serving as sources for dislocation nucleation in the crystalline layer or triggering local shear transformation zones in amorphous layer. The critical resolved shear stress required to nucleate the first dislocation is also found to strongly depend on the crystalline orientation. Furthermore, it is found that the interaction between dislocations and shear localization at the crystalline-amorphous interface oriented in different directions can lead to a change in the deformation mode. For instance, while the dislocation and shear banding are aligned to each other in {0 0 1} interface plane, the misorientation angle between these failure mechanisms causing more homogeneous deformation in {1 1 0} and {1 1 1} crystalline-amorphous interfaces. These results should help clarify the failure mechanism of crystalline-amorphous composites under various loading conditions.Keywords: crystalline-amorphous, composites, orientation, plasticity
Procedia PDF Downloads 289231 The Design Method of Artificial Intelligence Learning Picture: A Case Study of DCAI's New Teaching
Authors: Weichen Chang
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To create a guided teaching method for AI generative drawing design, this paper develops a set of teaching models for AI generative drawing (DCAI), which combines learning modes such as problem-solving, thematic inquiry, phenomenon-based, task-oriented, and DFC . Through the information security AI picture book learning guided programs and content, the application of participatory action research (PAR) and interview methods to explore the dual knowledge of Context and ChatGPT (DCAI) for AI to guide the development of students' AI learning skills. In the interviews, the students highlighted five main learning outcomes (self-study, critical thinking, knowledge generation, cognitive development, and presentation of work) as well as the challenges of implementing the model. Through the use of DCAI, students will enhance their consensus awareness of generative mapping analysis and group cooperation, and they will have knowledge that can enhance AI capabilities in DCAI inquiry and future life. From this paper, it is found that the conclusions are (1) The good use of DCAI can assist students in exploring the value of their knowledge through the power of stories and finding the meaning of knowledge communication; (2) Analyze the transformation power of the integrity and coherence of the story through the context so as to achieve the tension of ‘starting and ending’; (3) Use ChatGPT to extract inspiration, arrange story compositions, and make prompts that can communicate with people and convey emotions. Therefore, new knowledge construction methods will be one of the effective methods for AI learning in the face of artificial intelligence, providing new thinking and new expressions for interdisciplinary design and design education practice.Keywords: artificial intelligence, task-oriented, contextualization, design education
Procedia PDF Downloads 21230 Energy Conversion for Sewage Sludge by Microwave Heating Pyrolysis and Gasification
Authors: Young Nam Chun, Soo Hyuk Yun, Byeo Ri Jeong
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The recent gradual increase in the energy demand is mostly met by fossil fuel, but the research on and development of new alternative energy sources is drawing much attention due to the limited fossil fuel supply and the greenhouse gas problem. Biomass is an eco-friendly renewable energy that can achieve carbon neutrality. The conversion of the biomass sludge wastes discharged from a wastewater treatment plant to clean energy is an important green energy technology in an eco-friendly way. In this NRF study, a new type of microwave thermal treatment was developed to apply the biomass-CCS technology to sludge wastes. For this, the microwave dielectric heating characteristics were examined to investigate the energy conversion mechanism for the combined drying-pyrolysis/gasification of the dewatered wet sludge. The carbon dioxide gasification was tested using the CO2 captured from the pre-combustion capture process. In addition, the results of the pyrolysis and gasification test with the wet sludge were analyzed to compare the microwave energy conversion results with the results of the use of the conventional heating method. Gas was the largest component of the product of both pyrolysis and gasification, followed by sludge char and tar. In pyrolysis, the main components of the producer gas were hydrogen and carbon monoxide, and there were some methane and hydrocarbons. In gasification, however, the amount of carbon monoxide was greater than that of hydrogen. In microwave gasification, a large amount of heavy tar was produced. The largest amount of benzene among light tar was produced in both pyrolysis and gasification. NH3 and HCN which are the precursors of NOx, generated as well. In microwave heating, the sludge char had a smooth surface, like that of glass, and in the conventional heating method with an electric furnace, deep cracks were observed in the sludge char. This indicates that the gas obtained from the microwave pyrolysis and gasification of wet sewage sludge can be used as fuel, but the heavy tar and NOx precursors in the gas must be treated. Sludge char can be used as solid fuel or as a tar reduction adsorbent in the process if necessary. This work supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2015R1R1A2A2A03003044).Keywords: microwave heating, pyrolysis gasification, precombustion CCS, sewage sludge, biomass energy
Procedia PDF Downloads 314229 Evaluation and Control of Cracking for Bending Rein-forced One-way Concrete Voided Slab with Plastic Hollow Inserts
Authors: Mindaugas Zavalis
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Analysis of experimental tests data of bending one-way reinforced concrete slabs from various articles of science revealed that voided slabs with a grid of hollow plastic inserts inside have smaller mechani-cal and physical parameters compared to continuous cross-section slabs (solid slabs). The negative influence of a reinforced concrete slab is impacted by hollow plastic inserts, which make a grid of voids in the middle of the cross-sectional area of the reinforced concrete slab. A formed grid of voids reduces the slab’s stiffness, which influences the slab’s parameters of serviceability, like deflection and cracking. Prima-ry investigation of data established during experiments illustrates that cracks occur faster in the tensile surface of the voided slab under bend-ing compared to bending solid slab. It means that the crack bending moment force for the voided slab is smaller than the solid slab and the reduction can variate in the range of 14 – 40 %. Reduce of resistance to cracking can be controlled by changing a lot of factors: the shape of the plastic hallow insert, plastic insert height, steps between plastic in-serts, usage of prestressed reinforcement, the diameter of reinforcement bar, slab effective depth, the bottom cover thickness of concrete, effec-tive cross-section of the concrete area about reinforcement and etc. Mentioned parameters are used to evaluate crack width and step of cracking, but existing analytical calculation methods for cracking eval-uation of voided slab with plastic inserts are not so exact and the re-sults of cracking evaluation in this paper are higher than the results of analyzed experiments. Therefore, it was made analytically calculations according to experimental bending tests of voided reinforced concrete slabs with hollow plastic inserts to find and propose corrections for the evaluation of cracking for reinforced concrete voided slabs with hollow plastic inserts.Keywords: voided slab, cracking, hallow plastic insert, bending, one-way reinforced concrete, serviceability
Procedia PDF Downloads 63228 Investigation of Electrospun Composites Nanofiber of Poly (Lactic Acid)/Hazelnut Shell Powder/Zinc Oxide
Authors: Ibrahim Sengor, Sumeyye Cesur, Ilyas Kartal, Faik Nuzhet Oktar, Nazmi Ekren, Ahmet Talat Inan, Oguzhan Gunduz
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In recent years, many researchers focused on nano-size fiber production. Nanofibers have been studied due to their different and superior physical, chemical and mechanical properties. Poly (lactic acid) (PLA), is a type of biodegradable thermoplastic polyester derived from renewable sources used in biomedical owing to its biocompatibility and biodegradability. In addition, zinc oxide is an antibacterial material and hazelnut shell powder is a filling material. In this study, nanofibers were obtained by adding of different ratio Zinc oxide, (ZnO) and hazelnut shell powder at different concentration into Poly (lactic acid) (PLA) by using electrospinning method which is the most common method to obtain nanofibers. After dissolving the granulated polylactic acids in % 1,% 2,% 3 and% 4 with chloroform solvent, they are homogenized by adding tween and hazelnut shell powder at different ratios and then by electrospinning, nanofibers are obtained. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimeter (DSC) and physical analysis such as density, electrical conductivity, surface tension, viscosity measurement and antimicrobial test were carried out after production process. The resulting structures of the nanofiber possess antimicrobial and antiseptic properties, which are attractive for biomedical applications. The resulting structures of the nanofiber possess antimicrobial, non toxic, self-cleaning and rigid properties, which are attractive for biomedical applications.Keywords: electrospinning, hazelnut shell powder, nanofibers, poly (lactic acid), zinc oxide
Procedia PDF Downloads 158227 Computational Fluid Dynamics Simulation on Heat Transfer of Hot Air Bubble Injection into Water Column
Authors: Jae-Yeong Choi, Gyu-Mok Jeon, Jong-Chun Park, Yong-Jin Cho, Seok-Tae Yoon
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When air flow is injected into water, bubbles are formed in various types inside the water pool along with the air flow rate. The bubbles are floated in equilibrium with forces such as buoyancy, surface tension and shear force. Single bubble generated at low flow rate maintains shape, but bubbles with high flow rate break up to make mixing and turbulence. In addition to this phenomenon, as the hot air bubbles are injected into the water, heat affects the interface of phases. Therefore, the main scope of the present work reveals how to proceed heat transfer between water and hot air bubbles injected into water. In the present study, a series of CFD simulation for the heat transfer of hot bubbles injected through a nozzle near the bottom in a cylindrical water column are performed using a commercial CFD software, STAR-CCM+. The governing equations for incompressible and viscous flow are the continuous and the RaNS (Reynolds- averaged Navier-Stokes) equations and discretized by the FVM (Finite Volume Method) manner. For solving multi-phase flow, the Eulerian multiphase model is employed and the interface is defined by VOF (Volume-of-Fluid) technique. As a turbulence model, the SST k-w model considering the buoyancy effects is introduced. For spatial differencing the 3th-order MUSCL scheme is adopted and the 2nd-order implicit scheme for time integration. As the results, the dynamic behavior of the rising hot bubbles with the flow rate injected and regarding heat transfer mechanism are discussed based on the simulation results.Keywords: heat transfer, hot bubble injection, eulerian multiphase model, flow rate, CFD (Computational Fluid Dynamics)
Procedia PDF Downloads 144226 The Interactions between Phosphorus Leaching and Lime Application in Undisturbed Soil Columns with Different Soil Textures
Authors: Faezeh Eslamian, Zhiming Qi, Michael J. Tate
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Phosphorus losses from agricultural fields through leaching is one of the main contributors to eutrophication of lakes in Quebec as well as North America. The main objective of this study is to evaluate the application of high calcium hydrated lime as a soil amendment in reducing the subsurface transport of phosphorus to water bodies by studying the interactions between phosphorus leaching and lime application in three common agricultural soil textures (sandy loam, loam and clay loam) in Quebec. For this purpose, 6 intact soil columns of 10 cm diameter and 20 cm deep were taken from each of the three different soil textured agricultural fields. Lime (high calcium hydrated lime) was applied to the top 5 cm of half of the intact soil columns while the rest were left as controls. The columns were leached with artificial rainwater in-consecutively at a rate of 3 mm h-1 over a 90-day period. The total amount of water added was equal to the average total rainfall of the region in fall. The leachate samples were collected daily and analyzed for dissolved reactive phosphorus, total dissolved phosphorus, total phosphorus, pH, electrical conductivity, calcium, magnesium, potassium and iron. The results showed that lime was able to significantly reduce dissolved reactive phosphorus concentrations in the leachates by 70 and 40 percent in sandy loam and loam soil columns, respectively, while phosphorus concentration in the clay loam soil leachates were increased by 40 percent. The calcium in lime has P-binding capabilities. Soil chemical properties in sandy and loamy soils can affect phosphorus leaching, whereas, transport mechanisms in clay soils with macropores dominate phosphorus leaching behaviors. The presence of preferential pathways and cracks in the clay soil columns has led to a quick transport of phosphorus through the soil and the less contact time with the soil matrix, therefore, causing less opportunity for P sorption and larger P release. Application of lime to agricultural fields can be considered as a promising measure in mitigating phosphorus loss from sandy loam and loam soils.Keywords: leaching, lime, phosphorus, soil texture
Procedia PDF Downloads 166225 Effect of Dynamic Loading by Cyclic Triaxial Tests on Sand Stabilized with Cement
Authors: Priyanka Devi, Mohammad Muzzaffar Khan, G. Kalyan Kumar
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Liquefaction of saturated soils due to dynamic loading is an important and interesting area in the field of geotechnical earthquake engineering. When the soil liquefies, the structures built on it develops uneven settlements thereby producing cracks in the structure and weakening the foundation. The 1964 Alaskan Good Friday earthquake, the 1989 San Francisco earthquake and 2011 Tōhoku earthquake are some of the examples of liquefaction occurred due to an earthquake. To mitigate the effect of liquefaction, several methods such use of stone columns, increasing the vertical stress, compaction and removal of liquefiable soil are practiced. Grouting is one of those methods used to increase the strength of the foundation and develop resistance to liquefaction of soil without affecting the superstructure. In the present study, an attempt has been made to investigate the undrained cyclic behavior of locally available soil, stabilized by cement to mitigate the seismically induced soil liquefaction. The specimens of 75mm diameter and 150mm height were reconstituted in the laboratory using water sedimentation technique. A series of strain-controlled cyclic triaxial tests were performed on saturated soil samples followed by consolidation. The effects of amplitude, confining pressure and relative density on the dynamic behavior of sand was studied for soil samples with varying cement content. The results obtained from the present study on loose specimens and medium dense specimens indicate that (i) the higher the relative density, the more will be the liquefaction resistance, (ii) with increase of effective confining pressure, a decrease in developing of excess pore water pressure during cyclic loading was observed and (iii) sand specimens treated with cement showed reduced excess pore pressures and increased liquefaction resistance suggesting it as one of the mitigation methods.Keywords: cyclic triaxial test, liquefaction, soil-cement stabilization, pore pressure ratio
Procedia PDF Downloads 292224 The Ecological Urbanism as an Oppurtunity to Solve City Problem
Authors: Fairuz A. Ulinnuha, Bimo K. Fuadi
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The world’s population continues to grow resulting in steady migration from rural to urban areas. Increased numbers of people and cities hand in hand with greater exploitation of world’s resource. Every year, more cities are feeling the devastating of this impact of this situation. During the 1970’s, some of eco-concept were applied to urban settings, one of them is Ecological Cities. A non-profit organization, Urban Ecology, was founded in California in 1975 to 'rebuild cities in balance with nature'. Efforts to synthesize ecological and urban planning approaches were slowed somewhat in the 1980s, but useful refinements were made. Consideration of social impact acknowledges that the ecological design is not just about ecology itself. It is also about questioning and redefining our understanding of the ecology. When ecologist did recognize the existence of cities, they were usually concerned with resource flows. One popular approach was to study the flow and transformation of energy through urban ecosystem. This research method is descriptive method, following LEED Certification which is the international standard of the sustainable building, is more widely applied. But there remains problem that the moral imperative of sustainability and by implication of sustainable design, tends to supplant the disciplinary contribution. Sustainable design is not always seen as design excellence or design innovation. This can provoke the skepticism and cause the tension those who promote disciplinary knowledge and those who push for sustainability. The challenges of rapid urbanization and limited of global resources has become more pressing. So, there is a need to find an alternative design approaches. The urban, as the site of complex relation (economy, political, social, cultural), need a complex problem solving that can solve current and future condition. The aim of this study is to discussed about conjoining of ecology such as public park and sustainable design.Keywords: ecology, cities, urban, sustainability
Procedia PDF Downloads 132223 Anal Repair and Diamond Flap in Moderate Anal Stenosis Patient After an Open Hemorrhoidectomy Surgery: A Case Report
Authors: Andriana Purnama, Reno Rudiman, Kezia Christy
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Anal stenosis which develops due to anoderm scarring usually caused by secondary to surgical trauma, has become common, causing significant decrease patient’s quality of life. Even though mild anal stenosis was treated with non-surgical treatment, but surgical reconstruction in unavoidable for moderate to severe anal stenosis that cause distressing, severe anal pain and inability to defecate. In our study, we intend to share our result with the use of diamond flap in treatment of anal stenosis. This case report illustrates a 57-year-old male patient who presented with difficulty and discomfort in defecation caused by anal stenosis after 2 years of open hemorrhoidectomy surgery. At physical examination, there was requirement of forceful dilatation when the index finger was inserted or precisely 6mm as measured by hegar dilator (moderate anal stenosis). Blood test result was within normal limits. The patient underwent anal repair and diamond flap where the scar tissue at 6 and 9 o’clock directions was excised and diamond graft was incised carefully while paying attention to the vascular supply. Finally, the graft was fixated without any tension to the anal canal, resulting in diameter of 2 cm after operation. After 2 days post operation, the patient was in stable condition, without any complication, and discharged. There was no abnormality concerning the stool. Ten days after the operation, diamond flap was in normal condition and without any complication. He was scheduled for futher follow up at the Digestive Surgery Department. Anal stenosis due to overzealous hemorrhoidectomy is a complication that is preventable when performed in experienced hands. Diamond flap was one of the options for the anal stenosis treatment with less complication.Keywords: anal stenosis, diamond flap, post hemorrhoidectomy, anal repair
Procedia PDF Downloads 88222 Analysis of the Detachment of Water Droplets from a Porous Fibrous Surface
Authors: Ibrahim Rassoul, E-K. Si Ahmed
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The growth, deformation, and detachment of fluid droplets adherent to solid substrates is a problem of fundamental interest with numerous practical applications. Specific interest in this proposal is the problem of a droplet on a fibrous, hydrophobic substrate subjected to body or external forces (gravity, convection). The past decade has seen tremendous advances in proton exchange membrane fuel cell (PEMFC) technology. However, there remain many challenges to bring commercially viable stationary PEMFC products to the market. 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 the 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 aim of this work is to investigate the stability of a liquid water droplet emerging form a GDL pore, to gain fundamental insight into the instability process leading to detachment. The approach will combine analytical and numerical modeling with experimental visualization and measurements.Keywords: polymer electrolyte fuel cell, water droplet, gas diffusion layer, contact angle, surface tension
Procedia PDF Downloads 245221 Social and Digital Transformation of the Saudi Education System: A Cyberconflict Analysis
Authors: Mai Alshareef
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The Saudi government considers the modernisation of the education system as a critical component of the national development plan, Saudi Vision 2030; however, this sudden reform creates tension amongst Saudis. This study examines first the reflection of the social and digital education reform on stakeholders and the general Saudi public, and second, the influence of information and communication technologies (ICTs) on the ethnoreligious conflict in Saudi Arabia. This study employs Cyberconflict theory to examine conflicts in the real world and cyberspace. The findings are based on a qualitative case study methodology that uses netnography, an analysis of 3,750 Twitter posts and semi-structural interviews with 30 individuals, including key actors in the Saudi education sector and Twitter activists during 2019\2020. The methods utilised are guided by thematic analysis to map an understanding of factors that influence societal conflicts in Saudi Arabia, which in this case include religious, national, and gender identity. Elements of Cyberconflict theory are used to better understand how conflicting groups build their identities in connection to their ethnic/religious/cultural differences and competing national identities. The findings correspond to the ethnoreligious components of the Cyberconflict theory. Twitter became a battleground for liberals, conservatives, the Saudi public and elites, and it is used in a novel way to influence public opinion and to challenge the media monopoly. Opposing groups relied heavily on a discourse of exclusion and inclusion and showed ethnic and religious affiliations, national identity, and chauvinism. The findings add to existing knowledge in the cyberconflict field of study, and they also reveal outcomes that are critical to the Saudi Arabian national context.Keywords: education, cyberconflict, Twitter, national identity
Procedia PDF Downloads 170220 Influence of Reinforcement Stiffness on the Performance of Back-to-Back Reinforced Earth Wall upon Rainwater Infiltration
Authors: Gopika Rajagopal, Sudheesh Thiyyakkandi
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Back-to-back reinforced earth (RE) walls are extensively used in these days as bridge abutments and highway ramps, owing to their cost efficiency and ease of construction. High quality select fill is the most suitable backfill material due to its excellent engineering properties and constructability. However, industries are compelled to use low quality, locally available soil because of its ample availability on site. However, several failure cases of such walls are reported, especially subsequent to rainfall events. The stiffness of reinforcement is one of the major factors affecting the performance of RE walls. The present study focused on analyzing the effect of reinforcement stiffness on the performance of complete select fill, complete marginal fill, and hybrid-fill (i.e., combination of select and marginal fills) back-to-back RE walls, immediately after construction and upon rainwater infiltration through finite element modelling. A constant width to height (W/H) ratio of 3 and height (H) of 6 m was considered for the numerical analysis and the stiffness of reinforcement layers was varied from 500 kN/m to 10000 kN/m. Results showed that reinforcement stiffness had a noticeable influence on the response of RE wall, subsequent to construction as well as rainwater infiltration. Facing displacement was found to decrease and maximum reinforcement tension and factor of safety were observed to increase with increasing the stiffness of reinforcement. However, beyond a stiffness of 5000 kN/m, no significant reduction in facing displacement was observed. The behavior of fully marginal fill wall considered in this study was found to be reasonable even after rainwater infiltration when the high stiffness reinforcement layers are used.Keywords: back-to-back reinforced earth wall, finite element modelling, rainwater infiltration, reinforcement stiffness
Procedia PDF Downloads 146219 Study on the Situation between France and the South China Sea from the Perspective of Balance of Power Theory
Authors: Zhenyi Chen
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With the rise of China and the escalation of tension between China and the United States, European countries led by Great Britain, France, and Germany pay increasing attention to the regional situation in the Asia-Pacific (now known as "Indo-Pacific"). Among them, the South China Sea (SCS) is one of the main areas disputed by China, the United States, Southeast Asian countries and some European countries. Western countries are worried that the rise of China's military power will break the stability of the situation in SCS and alter the balance of power among major powers. Therefore, they tried to balance China's rise through alliance. In France's Indo-Pacific strategy, France aims to build a regional order with the alliance of France, India and Australia as the core, and regularly carry out military exercises targeting SCS with the United States, Japan and Southeast Asian countries. For China, the instability of the situation in SCS could also threaten the security of the southeast coastal areas and Taiwan, affect China's peaceful development process, and pose a threat to China's territorial sovereignty. This paper aims to study the activities and motivation of France in the South China Sea, and put the situation in SCS under the perspective of Balance of Power Theory, focusing on China, America and France. To be more specific, this paper will first briefly introduce Balance of Power Theory, then describe the new trends of France in recent years, followed with the analysis on the motivation of the increasing trend of France's involvement in SCS, and finally analyze the situation in SCS from the perspective of "balance of power" theory. It will be argued that great powers are carefully maintaining the balance of military power in SCS, and it is highly possible that this trend would still last in the middle and long term, particularly via military deployment and strategic alliances.Keywords: South China Sea, France, China, balance of power theory, Indo-Pacific
Procedia PDF Downloads 172218 Development of Solid Electrolytes Based on Networked Cellulose
Authors: Boor Singh Lalia, Yarjan Abdul Samad, Raed Hashaikeh
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Three different kinds of solid polymer electrolytes were prepared using polyethylene oxide (PEO) as a base polymer, networked cellulose (NC) as a physical support and LiClO4 as a conductive salt for the electrolytes. Networked cellulose, a modified form of cellulose, is a biodegradable and environmentally friendly additive which provides a strong fibrous networked support for structural stability of the electrolytes. Although the PEO/NC/LiClO4 electrolyte retains its structural integrity and mechanical properties at 100oC as compared to pristine PEO-based polymer electrolytes, it suffers from poor ionic conductivity. To improve the room temperature conductivity of the electrolyte, PEO is replaced by the polyethylene glycol (PEG) which is a liquid phase that provides high mobility for Li+ ions transport in the electrolyte. PEG/NC/LiClO4 shows improvement in ionic conductivity compared to PEO/NC/LiClO4 at room temperature, but it is brittle and tends to form cracks during processing. An advanced solid polymer electrolyte with optimum ionic conductivity and mechanical properties is developed by using a ternary system: TEGDME/PEO/NC+LiClO4. At room temperature, this electrolyte exhibits an ionic conductivity to the order of 10-5 S/cm, which is very high compared to that of the PEO/LiClO4 electrolyte. Pristine PEO electrolytes start melting at 65 °C and completely lose its mechanical strength. Dynamic mechanical analysis of TEGDME: PEO: NC (70:20:10 wt%) showed an improvement of storage modulus as compared to the pristine PEO in the 60–120 °C temperature range. Also, with an addition of NC, the electrolyte retains its mechanical integrity at 100 oC which is beneficial for Li-ion battery operation at high temperatures. Differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA) studies revealed that the ternary polymer electrolyte is thermally stable in the lithium ion battery operational temperature range. As-prepared polymer electrolyte was used to assemble LiFePO4/ TEGDME/PEO/NC+LiClO4/Li half cells and their electrochemical performance was studied via cyclic voltammetry and charge-discharge cycling.Keywords: solid polymer electrolyte, ionic conductivity, mechanical properties, lithium ion batteries, cyclic voltammetry
Procedia PDF Downloads 421217 Application of Water Soluble Polymers in Chemical Enhanced Oil Recovery
Authors: M. Shahzad Kamal, Abdullah S. Sultan, Usamah A. Al-Mubaiyedh, Ibnelwaleed A. Hussein
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Oil recovery from reservoirs using conventional oil recovery techniques like water flooding is less than 20%. Enhanced oil recovery (EOR) techniques are applied to recover additional oil. Surfactant-polymer flooding is a promising EOR technique used to recover residual oil from reservoirs. Water soluble polymers are used to increase the viscosity of displacing fluids. Surfactants increase the capillary number by reducing the interfacial tension between oil and displacing fluid. Hydrolyzed polyacrylamide (HPAM) is widely used in polymer flooding applications due to its low cost and other desirable properties. HPAM works well in low-temperature and low salinity-environment. In the presence of salts HPAM viscosity decrease due to charge screening effect and it can precipitate at high temperatures in the presence of salts. Various strategies have been adopted to extend the application of water soluble polymers to high-temperature high-salinity (HTHS) reservoir. These include addition of monomers to acrylamide chain that can protect it against thermal hydrolysis. In this work, rheological properties of various water soluble polymers were investigated to find out suitable polymer and surfactant-polymer systems for HTHS reservoirs. Polymer concentration ranged from 0.1 to 1 % (w/v). Effect of temperature, salinity and polymer concentration was investigated using both steady shear and dynamic measurements. Acrylamido tertiary butyl sulfonate based copolymer showed better performance under HTHS conditions compared to HPAM. Moreover, thermoviscosifying polymer showed excellent rheological properties and increase in the viscosity was observed with increase temperature. This property is highly desirable for EOR application.Keywords: rheology, polyacrylamide, salinity, enhanced oil recovery, polymer flooding
Procedia PDF Downloads 404216 Material Concepts and Processing Methods for Electrical Insulation
Authors: R. Sekula
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Epoxy composites are broadly used as an electrical insulation for the high voltage applications since only such materials can fulfill particular mechanical, thermal, and dielectric requirements. However, properties of the final product are strongly dependent on proper manufacturing process with minimized material failures, as too large shrinkage, voids and cracks. Therefore, application of proper materials (epoxy, hardener, and filler) and process parameters (mold temperature, filling time, filling velocity, initial temperature of internal parts, gelation time), as well as design and geometric parameters are essential features for final quality of the produced components. In this paper, an approach for three-dimensional modeling of all molding stages, namely filling, curing and post-curing is presented. The reactive molding simulation tool is based on a commercial CFD package, and include dedicated models describing viscosity and reaction kinetics that have been successfully implemented to simulate the reactive nature of the system with exothermic effect. Also a dedicated simulation procedure for stress and shrinkage calculations, as well as simulation results are presented in the paper. Second part of the paper is dedicated to recent developments on formulations of functional composites for electrical insulation applications, focusing on thermally conductive materials. Concepts based on filler modifications for epoxy electrical composites have been presented, including the results of the obtained properties. Finally, having in mind tough environmental regulations, in addition to current process and design aspects, an approach for product re-design has been presented focusing on replacement of epoxy material with the thermoplastic one. Such “design-for-recycling” method is one of new directions associated with development of new material and processing concepts of electrical products and brings a lot of additional research challenges. For that, one of the successful products has been presented to illustrate the presented methodology.Keywords: curing, epoxy insulation, numerical simulations, recycling
Procedia PDF Downloads 271215 Analysis of a Damage-Control Target Displacement of Reinforced Concrete Bridge Pier for Seismic Design
Authors: Mohd Ritzman Abdul Karim, Zhaohui Huang
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A current focus in seismic engineering practice is the development of seismic design approach that focuses on the performance-based design. Performance-based design aims to design the structures to achieve specified performance based on the damage limit states. This damage limit is more restrictive limit than life safety and needs to be carefully estimated to avoid damage in piers due to failure in transverse reinforcement. In this paper, a different perspective of damage limit states has been explored by integrating two damage control material limit state, concrete and reinforcement by introduced parameters such as expected yield stress of transverse reinforcement where peak tension strain prior to bar buckling is introduced in a recent study. The different perspective of damage limit states with modified yield displacement and the modified plastic-hinge length is used in order to predict damage-control target displacement for reinforced concreate (RC) bridge pier. Three-dimensional (3D) finite element (FE) model has been developed for estimating damage target displacement to validate proposed damage limit states. The result from 3D FE analysis was validated with experimental study found in the literature. The validated model then was applied to predict the damage target displacement for RC bridge pier and to validate the proposed study. The tensile strain on reinforcement and compression on concrete were used to determine the predicted damage target displacement and compared with the proposed study. The result shows that the proposed damage limit states were efficient in predicting damage-control target displacement consistent with FE simulations.Keywords: damage-control target displacement, damage limit states, reinforced concrete bridge pier, yield displacement
Procedia PDF Downloads 152214 Ecofriendly Multi-Layer Polymer Treatment for Hydrophobic and Water Repellent Porous Cotton Fabrics
Authors: Muhammad Zahid, Ilker S. Bayer, Athanassia Athanassiou
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Fluorinated polymers having C8 chemistry (chemicals with 8 fluorinated carbon atoms) are well renowned for their excellent low surface tension and water repelling properties. However, these polymers degrade into highly toxic heavy perfluoro acids in the environment. When the C8 chemistry is reduced to C6 chemistry, this environmental concern is eliminated at the expense of reduced liquid repellent performance. In order to circumvent this, in this study, we demonstrate pre-treatment of woven cotton fabrics with a fluorinated acrylic copolymer with C6 chemistry and subsequently with a silicone polymer to render them hydrophobic. A commercial fluorinated acrylic copolymer was blended with silica nanoparticles to form hydrophobic nano-roughness on cotton fibers and a second coating layer of polydimethylsiloxane (PDMS) was applied on the fabric. A static water contact angle (for 5µl) and rolling angle (for 12.5µl) of 147°±2° and 31° were observed, respectively. Hydrostatic head measurements were also performed to better understand the performance with 26±1 cm and 2.56kPa column height and static pressure respectively. Fabrication methods (with rod coater etc.) were kept simple, reproducible, and scalable and cost efficient. Moreover, the robustness of applied coatings was also evaluated by sonication cleaning and abrasion methods. Water contact angle (WCA), water shedding angle (WSA), hydrostatic head, droplet bouncing-rolling off and prolonged staining tests were used to characterize hydrophobicity of materials. For chemical and morphological analysis, various characterization methods were used such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM) and scanning electron microscopy (SEM).Keywords: fluorinated polymer, hydrophobic, polydimethylsiloxane, water contact angle
Procedia PDF Downloads 319213 Opposed Piston Engine Crankshaft Strength Calculation Using Finite Element Method
Authors: Konrad Pietrykowski, Michał Gęca, Michał Bialy
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The paper presents the results of the crankshaft strength simulation. The crankshaft was taken from the opposed piston engine. Calculations were made using finite element method (FEM) in Abaqus software. This program allows to perform strength tests of individual machine parts as well as their assemblies. The crankshaft that was used in the calculations will be used in the two-stroke aviation research aircraft engine. The assumptions for the calculations were obtained from the AVL Boost software, from one-dimensional engine cycle model and from the multibody model using the method developed in the MSC Adams software. The research engine will be equipped with 3 combustion chambers and two crankshafts. In order to shorten the calculation time, only one crankcase analysis was performed. The cut of the shaft has been selected with the greatest forces resulting from the engine operation. Calculations were made for two cases. For maximum piston force when maximum bending load occurs and for the maximum torque. Cast iron material was adopted. For this material, Poisson's number, density, and Young's modulus were determined. The computational grid contained of 1,977,473 Tet elements. This type of elements was chosen because of the complex design of the crankshaft. Results are presented in the form of stress distributions maps and displacements on the surface and inside the geometry of the shaft. The results show the places of tension stresses, however, no stresses are exceeded at any place. The shaft can thus be applied to the engine in its present form. Acknowledgement: This work has been realized in the cooperation with The Construction Office of WSK 'PZL-KALISZ’ S.A. and is part of Grant Agreement No. POIR.01.02.00-00-0002/15 financed by the Polish National Centre for Research and Development.Keywords: aircraft diesel engine, crankshaft, finite element method, two-stroke engine
Procedia PDF Downloads 178212 Comparison of the Hospital Patient Safety Culture between Bulgarian, Croatian and American: Preliminary Results
Authors: R. Stoyanova, R. Dimova, M. Tarnovska, T. Boeva, R. Dimov, I. Doykov
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Patient safety culture (PSC) is an essential component of quality of healthcare. Improving PSC is considered a priority in many developed countries. Specialized software platform for registration and evaluation of hospital patient safety culture has been developed with the support of the Medical University Plovdiv Project №11/2017. The aim of the study is to assess the status of PSC in Bulgarian hospitals and to compare it to that in USA and Croatian hospitals. Methods: The study was conducted from June 01 to July 31, 2018 using the web-based Bulgarian Version of the Hospital Survey on Patient Safety Culture Questionnaire (B-HSOPSC). Two hundred and forty-eight medical professionals from different hospitals in Bulgaria participated in the study. To quantify the differences of positive scores distributions for each of the 42 HSOPSC items between Bulgarian, Croatian and USA samples, the x²-test was applied. The research hypothesis assumed that there are no significant differences between the Bulgarian, Croatian and US PSCs. Results: The results revealed 14 significant differences in the positive scores between the Bulgarian and Croatian PSCs and 15 between the Bulgarian and the USA PSC, respectively. Bulgarian medical professionals provided less positive responses to 12 items compared with Croatian and USA respondents. The Bulgarian respondents were more positive compared to Croatians on the feedback and communication of medical errors (Items - C1, C4, C5) as well as on the employment of locum staff (A7) and the frequency of reported mistakes (D1). Bulgarian medical professionals were more positive compared with their USA colleagues on the communication of information at shift handover and across hospital units (F5, F7). The distribution of positive scores on items: ‘Staff worries that their mistakes are kept in their personnel file’ (RA16), ‘Things ‘fall between the cracks’ when transferring patients from one unit to another’ (RF3) and ‘Shift handovers are problematic for patients in this hospital’ (RF11) were significantly higher among Bulgarian respondents compared with Croatian and US respondents. Conclusions: Significant differences of positive scores distribution were found between Bulgarian and USA PSC on one hand and between Bulgarian and Croatian on the other. The study reveals that distribution of positive responses could be explained by the cultural, organizational and healthcare system differences.Keywords: patient safety culture, healthcare, HSOPSC, medical error
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