Search results for: toxicity investigation
1268 Geostatistical Models to Correct Salinity of Soils from Landsat Satellite Sensor: Application to the Oran Region, Algeria
Authors: Dehni Abdellatif, Lounis Mourad
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The new approach of applied spatial geostatistics in materials sciences, agriculture accuracy, agricultural statistics, permitted an apprehension of managing and monitoring the water and groundwater qualities in a relationship with salt-affected soil. The anterior experiences concerning data acquisition, spatial-preparation studies on optical and multispectral data has facilitated the integration of correction models of electrical conductivity related with soils temperature (horizons of soils). For tomography apprehension, this physical parameter has been extracted from calibration of the thermal band (LANDSAT ETM+6) with a radiometric correction. Our study area is Oran region (Northern West of Algeria). Different spectral indices are determined such as salinity and sodicity index, the Combined Spectral Reflectance Index (CSRI), Normalized Difference Vegetation Index (NDVI), emissivity, Albedo, and Sodium Adsorption Ratio (SAR). The approach of geostatistical modeling of electrical conductivity (salinity), appears to be a useful decision support system for estimating corrected electrical resistivity related to the temperature of surface soils, according to the conversion models by substitution, the reference temperature at 25°C (where hydrochemical data are collected with this constraint). The Brightness temperatures extracted from satellite reflectance (LANDSAT ETM+) are used in consistency models to estimate electrical resistivity. The confusions that arise from the effects of salt stress and water stress removed followed by seasonal application of the geostatistical analysis in Geographic Information System (GIS) techniques investigation and monitoring the variation of the electrical conductivity in the alluvial aquifer of Es-Sénia for the salt-affected soil.Keywords: geostatistical modelling, landsat, brightness temperature, conductivity
Procedia PDF Downloads 4421267 The Effect of Agricultural Waste as a Filler in Fibre Cement Board Reinforced with Natural Cellulosic Fibres
Authors: Anuoluwapo S. Taiwo, David S. Ayre, Morteza Khorami, Sameer S. Rahatekar
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This investigation aims to characterize the effect of Corn Cob (CC), an agricultural waste, for potential use as a filler material, reducing cement in natural fibre-reinforced cement composite boards used for building applications in low-cost housing estates in developing countries. The corn cob is readily and abundantly available in many West African States. However, this agricultural waste product has not been put to any effective use. Hence, the objective of the current research is to convert this massive agro-waste resource into a potential material for use as filler materials reducing cement contents in fibre-cement board production. Kraft pulp fibre-reinforced cement composite boards were developed with the incorporation of the corn cob powder at varying percentages of 1 – 4% as filler materials to reduce the cement content, using a laboratory-simulated vacuum de-watering process. The mechanical properties of the developed cement boards were characterized through a three-point bending test, while the fractured morphology of the cement boards was examined through a Scanning Electron Microscope (SEM). Results revealed that the flexural strength of the composite board improved significantly with an optimum enhancement of 39% when compared to the reference sample without corn cob replacement, however, the flexural behaviour (ductility) of the composite board was slightly affected by the addition of the corn cob powder at higher percentage. SEM observation of the fractured surfaces revealed good bonding at the fibre-matrix interface as well as a ductile-to-brittle fracture mechanism. Overall, the composite board incorporated with 2% corn cob powder as filler materials had the optimum properties which satisfied the minimum requirements of relevant standards for fibre cement flat sheets.Keywords: agricultural waste, building applications, fibre-cement board, kraft pulp fibre, sustainability
Procedia PDF Downloads 971266 Adoption of Risk and Insurance among Aquaculture Producers in Khuzestan Province, Iran
Authors: Kiyanoush Ghalavand
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Aquaculture production is inherently a risky business, and farmers face a variety of weather, pest, disease, inptut supply, and market related risks. There are many factors out farmers control and unpredictable. Insurance has an important role in aquaculture production and is a tool to support farmers against threats. Investigation of factors affecting aquaculture farmers' adoption of aquaculture insurance strategy was the objective of this study. The purpose of this study was determining the related factors to adoption of insurance by aquaculture farmers in Khuzestan province, Iran. The research design was a descriptive and correlation surveying method. Aquaculture farmers in Khuzestan province were the target population for this study. A random sample of aquaculture selected (N=1830, n =139). The main result of the study reveled that exist correlation between the level of education, knowledge about purpose of insurance, participation in extension course, visit with insurance organization, and contact with extension agents to the adoption of insurance by aquaculture farmers were significantly positive. By using Bartlett's test and KMO test, determine whether research variables are appropriate for factor analysis (Sig = 0.000, Bartlett test = 0.9724, KMO = 0.74). The number of factors was determined using a split plot, eigenvalue, and percent of variance. An examination of the items and their factors loadings was used to understand the nature of the nine factors. To reduce subjectivity, items with factor loading equal to or greater than 0.5 were considered most important when factors were labeled. The nine factors were labeled (1) Extension and education activities, (2) Economical characteristics, (3) Governmental support, (4) communicational channel, (5) local leaders, (6) Facilitate in given damage (7) Motivation establishing, (8) Given damage in appropriate methods and (9) Appropriate activities by insurance organization. The results obtained from the factors analysis reveal that the nine factors explain percentage75 of the variation of the adoption of insurance of the adoption of insurance by aquaculture farmers in Khuzestan province.Keywords: aquaculture farmers, insurance, factorial analysis, Khuzestan province, risks
Procedia PDF Downloads 1531265 A Reflective Investigation on the Course Design and Coaching Strategy for Creating a Trans-Disciplinary Leaning Environment
Authors: Min-Feng Hsieh
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Nowadays, we are facing a highly competitive environment in which the situation for survival has come even more critical than ever before. The challenge we will be confronted with is no longer can be dealt with the single system of knowledge. The abilities we urgently need to acquire is something that can lead us to cross over the boundaries between different disciplines and take us to a neutral ground that gathers and integrates powers and intelligence that surrounds us. This paper aims at discussing how a trans-disciplinary design course organized by the College of Design at Chaoyang University can react to this modern challenge. By orchestrating an experimental course format and by developing a series of coaching strategies, a trans-disciplinary learning environment has been created and practiced in which students selected from five different departments, including Architecture, Interior Design, Visual Design, Industrial Design, Landscape and Urban Design, are encouraged to think outside their familiar knowledge pool and to learn with/from each other. In the course of implementing this program, a parallel research has been conducted alongside by adopting the theory and principles of Action Research which is a research methodology that can provide the course organizer emergent, responsive, action-oriented, participative and critically reflective insights for the immediate changes and amendments in order to improve the effect of teaching and learning experience. In the conclusion, how the learning and teaching experience of this trans-disciplinary design studio can offer us some observation that can help us reflect upon the constraints and division caused by the subject base curriculum will be pointed out. A series of concepts for course design and teaching strategies developed and implemented in this trans-disciplinary course are to be introduced as a way to promote learners’ self-motivated, collaborative, cross-disciplinary and student-centered learning skills. The outcome of this experimental course can exemplify an alternative approach that we could adopt in pursuing a remedy for dealing with the problematic issues of the current educational practice.Keywords: course design, coaching strategy, subject base curriculum, trans-disciplinary
Procedia PDF Downloads 2051264 Investigation of Scaling Laws for Stiffness and strength in Bioinspired Glass Sponge Structures Produced by Fused Filament Fabrication
Authors: Hassan Beigi Rizi, Harold Auradou, Lamine Hattali
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Various industries, including civil engineering, automotive, aerospace, and biomedical fields, are currently seeking novel and innovative high-performance lightweight materials to reduce energy consumption. Inspired by the structure of Euplectella Aspergillum Glass Sponges (EA-sponge), 2D unit cells were created and fabricated using a Fused Filament Fabrication (FFF) process with Polylactic acid (PLA) filaments. The stiffness and strength of bio-inspired EA-sponge lattices were investigated both experimentally and numerically under uniaxial tensile loading and are compared to three standard square lattices with diagonal struts (Designs B and C) and non-diagonal struts (Design D) reinforcements. The aim is to establish predictive scaling laws models and examine the deformation mechanisms involved. The results indicated that for the EA-sponge structure, the relative moduli and yield strength scaled linearly with relative density, suggesting that the deformation mechanism is stretching-dominated. The Finite element analysis (FEA), with periodic boundary conditions for volumetric homogenization, confirms these trends and goes beyond the experimental limits imposed by the FFF printing process. Therefore, the stretching-dominated behavior, investigated from 0.1 to 0.5 relative density, demonstrate that the study of EA-sponge structure can be exploited for the realization of square lattice topologies that are stiff and strong and have attractive potential for lightweight structural applications. However, the FFF process introduces an accuracy limitation, with approximately 10% error, making it challenging to print structures with a relative density below 0.2. Future work could focus on exploring the impact of different printing materials on the performance of EA-sponge structures.Keywords: bio-inspiration, lattice structures, fused filament fabrication, scaling laws
Procedia PDF Downloads 151263 Crystalline Particles Dispersed Cu-Based Metallic Glassy Composites Fabricated by Spark Plasma Sintering
Authors: Sandrine Cardinal, Jean-Marc Pelletier, Guang Xie, Florian Mercier, Florent Delmas
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Bulk metallic glasses exhibit several superior properties, compared to their corresponding crystalline counterpart, such as high strength, high elastic limit or good corrosion resistance. Therefore they can be considered as good candidates for structural applications in many sectors. However, they are generally brittle and do not exhibit plastic deformation at room temperature. These materials are mainly obtained by rapid cooling from a liquid state to prevent crystallization, which limits their size. To overcome these two drawbacks: fragility and limited dimensions, composite metallic glass matrix reinforced by a second phase whose role is to slow crack growth are developed. Concerning the limited size of the pieces, the proposed solution is to get the material from amorphous powders by densifying under load. In this study, Cu50Zr45Al5 bulk metallic glassy matrix composites (MGMCs) containing different volume fraction (Vf) of Zr crystalline particles were manufactured by spark plasma sintering (SPS). Microstructure, thermal stability and mechanical properties of the MGMCs were investigated. Matrix of the composites remains a fully amorphous phase after consolidation at 420°C under 600 MPa. A good dispersion of the particles in the glassy matrix is obtained. Results show that the compressive strength decreases with Vf : 1670 MPa (Vf=0%) to 1300MPa (Vf=30%), the elastic modulus decreases but only slighty respectively 97.3GPa and 94.5 GPa and plasticity is improved from 0 to 4%. Fractographic investigation indicates a good bonding between amorphous and crystalline particles. In conclusion, present study has demonstrated that SPS method is useful for the synthesis of the bulk glassy composites. Large controlled microstructure specimens with interesting ductility can be obtained compared with others methods.Keywords: composite, mechanical properties, metallic glasses, spark plasma sintering
Procedia PDF Downloads 2821262 Climate Change Impact on Slope Stability: A Study of Slope Drainage Design and Operation
Authors: Elena Mugarza, Stephanie Glendinning, Ross Stirling, Colin Davies
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The effects of climate change and increased rainfall events on UK-based infrastructure are observable, with an increasing number being reported on in the national press. The fatal derailment at Stonehaven in 2020 prompted a wider review of Network Rail-owned earthworks assets. The event was indicated by the Rail Accident Investigation Branch (RAIB) to be caused by mis-installed drainage on the adjacent cutting. The slope failure on Snake Pass (public highway A57) was reportedly caused by significant water ingress following numerous storm events and resulted in the road’s closure for several months. This problem is only projected to continue with greater intensity and more prolonged rainfall events forecasted in the future. Subsequently, this project is designed to evaluate effective drainage trench design within infrastructure embankments, considering the capillary barrier phenomenon that may govern their deterioration and resultant failure. Theoretically, the differential between grain sizes of the embankment clays and gravels, customarily used in drainage trenches, would have a limiting effect on infiltration. As such, it is anticipated that the inclusion of an additional material with an intermediate grain size should improve the hydraulic conductivity across the drainage boundary. Multiple drainage designs will be studied using instrumentation within the drain and surrounding clays. Data from the real-world installation at the BIONICS embankment will be collected and compared with laboratory and Finite Element (FE) simulations. This research aims to reduce the risk of infrastructure slope failures by improving the resilience of earthwork drainage and lessening the consequential impact on transportation networks.Keywords: earthworks, slope drainage, transportation slopes, deterioration, capillary barriers, field study
Procedia PDF Downloads 551261 Verbal Working Memory in Sequential and Simultaneous Bilinguals: An Exploratory Study
Authors: Archana Rao R., Deepak P., Chayashree P. D., Darshan H. S.
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Cognitive abilities in bilinguals have been widely studied over the last few decades. Bilingualism has been found to extensively facilitate the ability to store and manipulate information in Working Memory (WM). The mechanism of WM includes primary memory, attentional control, and secondary memory, each of which makes a contribution to WM. Many researches have been done in an attempt to measure WM capabilities through both verbal (phonological) and nonverbal tasks (visuospatial). Since there is a lot of speculations regarding the relationship between WM and bilingualism, further investigation is required to understand the nature of WM in bilinguals, i.e., with respect to sequential and simultaneous bilinguals. Hence the present study aimed to highlight the verbal working memory abilities in sequential and simultaneous bilinguals with respect to the processing and recall abilities of nouns and verbs. Two groups of bilinguals aged between 18-30 years were considered for the study. Group 1 consisted of 20 (10 males and 10 females) sequential bilinguals who had acquired L1 (Kannada) before the age of 3 and had exposure to L2 (English) for a period of 8-10 years. Group 2 consisted of 20 (10 males and 10 females) simultaneous bilinguals who have acquired both L1 and L2 before the age of 3. Working memory abilities were assessed using two tasks, and a set of stimuli which was presented in gradation of complexity and the stimuli was inclusive of frequent and infrequent nouns and verbs. The tasks involved the participants to judge the correctness of the sentence and simultaneously remember the last word of each sentence and the participants are instructed to recall the words at the end of each set. The results indicated no significant difference between sequential and simultaneous bilinguals in processing the nouns and verbs, and this could be attributed to the proficiency level of the participants in L1 and the alike cognitive abilities between the groups. And recall of nouns was better compared to verbs, maybe because of the complex argument structure involved in verbs. Similarly, authors found a frequency of occurrence of nouns and verbs also had an effect on WM abilities. The difference was also found across gradation due to the load imposed on the central executive function and phonological loop.Keywords: bilinguals, nouns, verbs, working memory
Procedia PDF Downloads 1311260 Investigation of a Natural Convection Heat Sink for LEDs Based on Micro Heat Pipe Array-Rectangular Channel
Authors: Wei Wang, Yaohua Zhao, Yanhua Diao
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The exponential growth of the lighting industry has rendered traditional thermal technologies inadequate for addressing the thermal management challenges inherent to high-power light-emitting diode (LED) technology. To enhance the thermal management of LEDs, this study proposes a heat sink configuration that integrates a miniature heat pipe array based on phase change technology with rectangular channels. The thermal performance of the heat sink was evaluated through experimental testing, and the results demonstrated that when the input power was 100W, 150W, and 200W, the temperatures of the LED substrate were 47.64℃, 56.78℃, and 69.06℃, respectively. Additionally, the maximum temperature difference of the MHPA in the vertical direction was observed to be 0.32℃, 0.30℃, and 0.30℃, respectively. The results demonstrate that the heat sink not only effectively dissipates the heat generated by the LEDs, but also exhibits excellent temperature uniformity. In consideration of the experimental measurement outcomes, a corresponding numerical model was developed as part of this study. Following the model validation, the effect of the structural parameters of the heat sink on its heat dissipation efficacy was examined through the use of response surface methodology (RSM) analysis. The rectangular channel width, channel height, channel length, number of channel cross-sections, and channel cross-section spacing were selected as the input parameters, while the LED substrate temperature and the total mass of the heat sink were regarded as the response variables. Subsequently, the response was subjected to an analysis of variance (ANOVA), which yielded a regression model that predicted the response based on the input variables. This offers some direction for the design of the radiator.Keywords: light-emitting diodes, heat transfer, heat pipe, natural convection, response surface methodology
Procedia PDF Downloads 371259 Investigation of Ductile Failure Mechanisms in SA508 Grade 3 Steel via X-Ray Computed Tomography and Fractography Analysis
Authors: Suleyman Karabal, Timothy L. Burnett, Egemen Avcu, Andrew H. Sherry, Philip J. Withers
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SA508 Grade 3 steel is widely used in the construction of nuclear pressure vessels, where its fracture toughness plays a critical role in ensuring operational safety and reliability. Understanding the ductile failure mechanisms in this steel grade is crucial for designing robust pressure vessels that can withstand severe nuclear environment conditions. In the present study, round bar specimens of SA508 Grade 3 steel with four distinct notch geometries were subjected to tensile loading while capturing continuous 2D images at 5-second intervals in order to monitor any alterations in their geometries to construct true stress-strain curves of the specimens. 3D reconstructions of X-ray computed tomography (CT) images at high-resolution (a spatial resolution of 0.82 μm) allowed for a comprehensive assessment of the influences of second-phase particles (i.e., manganese sulfide inclusions and cementite particles) on ductile failure initiation as a function of applied plastic strain. Additionally, based on 2D and 3D images, plasticity modeling was executed, and the results were compared to experimental data. A specific ‘two-parameter criterion’ was established and calibrated based on the correlation between stress triaxiality and equivalent plastic strain at failure initiation. The proposed criterion demonstrated substantial agreement with the experimental results, thus enhancing our knowledge of ductile fracture behavior in this steel grade. The implementation of X-ray CT and fractography analysis provided new insights into the diverse roles played by different populations of second-phase particles in fracture initiation under varying stress triaxiality conditions.Keywords: ductile fracture, two-parameter criterion, x-ray computed tomography, stress triaxiality
Procedia PDF Downloads 941258 Fused Deposition Modeling Printing of Bioinspired Triply Periodic Minimal Surfaces Based Polyvinylidene Fluoride Materials for Scaffold Development in Biomedical Application
Authors: Farusil Najeeb Mullaveettil, Rolanas Dauksevicius
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Cellular structures produced by additive manufacturing have earned wide research attention due to their unique specific strength and energy absorption potentiality. The literature review concludes that pattern type and density are vital parameters that affect the mechanical properties of parts formed by additive manufacturing techniques and have an influence on printing time and material consumption. Fused deposition modeling technique (FDM) is used here to produce Polyvinylidene fluoride (PVDF) parts. In this work, patterns are based on triply periodic minimal surfaces (TPMS) produced by PVDF-based filaments using the FDM technique. PVDF homopolymer filament Fluorinar-H™ and PVDF copolymer filament Fluorinar-C™ are printed with three types of TPMS patterns. The patterns printed are Gyroid, Schwartz diamond, and Schwartz primitive. Tensile, flexural, and compression tests under quasi-static loading conditions are performed in compliance with ISO standards. The investigation elucidates the deformation mechanisms and a study that establishes a relationship between the printed and nominal specimens' dimensional accuracy. In comparison to the examined TPMS pattern, Schwartz diamond showed a higher relative elastic modulus and strength than the other patterns in tensile loading, and the Gyroid pattern showed the highest mechanical characteristics in flexural loading. The concluded results could be utilized to produce informed cellular designs for biomedical and mechanical applications.Keywords: additive manufacturing, FDM, PVDF, gyroid, schwartz primitive, schwartz diamond, TPMS, tensile, flexural
Procedia PDF Downloads 1431257 Implementing of Indoor Air Quality Index in Hong Kong
Authors: Kwok W. Mui, Ling T. Wong, Tsz W. Tsang
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Many Hong Kong people nowadays spend most of their lifetime working indoor. Since poor Indoor Air Quality (IAQ) potentially leads to discomfort, ill health, low productivity and even absenteeism in workplaces, a call for establishing statutory IAQ control to safeguard the well-being of residents is urgently required. Although policies, strategies, and guidelines for workplace IAQ diagnosis have been developed elsewhere and followed with remedial works, some of those workplaces or buildings have relatively late stage of the IAQ problems when the investigation or remedial work started. Screening for IAQ problems should be initiated as it will provide information as a minimum provision of IAQ baseline requisite to the resolution of the problems. It is not practical to sample all air pollutants that exit. Nevertheless, as a statutory control, reliable, rapid screening is essential in accordance with a compromise strategy, which balances costs against detection of key pollutants. This study investigates the feasibility of using an IAQ index as a parameter of IAQ control in Hong Kong. The index is a screening parameter to identify the unsatisfactory workplace IAQ and will highlight where a fully effective IAQ monitoring and assessment is needed for an intensive diagnosis. There already exist a number of representative common indoor pollutants based on some extensive IAQ assessments. The selection of pollutants is surrogate to IAQ control consists of dilution, mitigation, and emission control. The IAQ Index and assessment will look at high fractional quantities of these common measurement parameters. With the support of the existing comprehensive regional IAQ database and the IAQ Index by the research team as the pre-assessment probability, and the unsatisfactory IAQ prevalence as the post-assessment probability from this study, thresholds of maintaining the current measures and performing a further IAQ test or IAQ remedial measures will be proposed. With justified resources, the proposed IAQ Index and assessment protocol might be a useful tool for setting up a practical public IAQ surveillance programme and policy in Hong Kong.Keywords: assessment, index, indoor air quality, surveillance programme
Procedia PDF Downloads 2681256 Formulation Development, Process Optimization and Comparative study of Poorly Compressible Drugs Ibuprofen, Acetaminophen Using Direct Compression and Top Spray Granulation Technique
Authors: Abhishek Pandey
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Ibuprofen and Acetaminophen is widely used as prescription & non-prescription medicine. Ibuprofen mainly used in the treatment of mild to moderate pain related to headache, migraine, postoperative condition and in the management of spondylitis, osteoarthritis and rheumatoid arthritis. Acetaminophen is used as an analgesic and antipyretic drug. Ibuprofen having high tendency of sticking to punches of tablet punching machine while Acetaminophen is not ordinarily compressible to tablet formulation because Acetaminophen crystals are very hard and brittle in nature and fracture very easily when compressed producing capping and laminating tablet defects therefore wet granulation method is used to make them compressible. The aim of study was to prepare Ibuprofen and Acetaminophen tablets by direct compression and top spray granulation technique. In this Investigation tablets were prepared by using directly compressible grade excipients. Dibasic calcium phosphate, lactose anhydrous (DCL21), microcrystalline cellulose (Avicel PH 101). In order to obtain best or optimized formulation, nine different formulations were generated among them batch F7, F8, F9 shows good results and within the acceptable limit. Formulation (F7) selected as optimize product on the basis of dissolution study. Furtherly, directly compressible granules of both drugs were prepared by using top spray granulation technique in fluidized bed processor equipment and compressed .In order to obtain best product process optimization was carried out by performing four trials in which various parameters like inlet air temperature, spray rate, peristaltic pump rpm, % LOD, properties of granules, blending time and hardness were optimized. Batch T3 coined as optimized batch on the basis physical & chemical evaluation. Finally formulations prepared by both techniques were compared.Keywords: direct compression, top spray granulation, process optimization, blending time
Procedia PDF Downloads 3651255 Hybrid Renewable Energy System Development Towards Autonomous Operation: The Deployment Potential in Greece
Authors: Afroditi Zamanidou, Dionysios Giannakopoulos, Konstantinos Manolitsis
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A notable amount of electrical energy demand in many countries worldwide is used to cover public energy demand for road, square and other public spaces’ lighting. Renewable energy can contribute in a significant way to the electrical energy demand coverage for public lighting. This paper focuses on the sizing and design of a hybrid energy system (HES) exploiting the solar-wind energy potential to meet the electrical energy needs of lighting roads, squares and other public spaces. Moreover, the proposed HES provides coverage of the electrical energy demand for a Wi-Fi hotspot and a charging hotspot for the end-users. Alongside the sizing of the energy production system of the proposed HES, in order to ensure a reliable supply without interruptions, a storage system is added and sized. Multiple scenarios of energy consumption are assumed and applied in order to optimize the sizing of the energy production system and the energy storage system. A database with meteorological prediction data for 51 areas in Greece is developed in order to assess the possible deployment of the proposed HES. Since there are detailed meteorological prediction data for all 51 areas under investigation, the use of these data is evaluated, comparing them to real meteorological data. The meteorological prediction data are exploited to form three hourly production profiles for each area for every month of the year; minimum, average and maximum energy production. The energy production profiles are combined with the energy consumption scenarios and the sizing results of the energy production system and the energy storage system are extracted and presented for every area. Finally, the economic performance of the proposed HES in terms of Levelized cost of energy is estimated by calculating and assessing construction, operation and maintenance costs.Keywords: energy production system sizing, Greece’s deployment potential, meteorological prediction data, wind-solar hybrid energy system, levelized cost of energy
Procedia PDF Downloads 1561254 Modeling of the Dynamic Characteristics of a Spindle with Experimental Validation
Authors: Jhe-Hao Huang, Kun-Da Wu, Wei-Cheng Shih, Jui-Pin Hung
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This study presented the investigation on the dynamic characteristics of a spindle tool system by experimental and finite element modeling approaches. As well known facts, the machining stability is greatly determined by the dynamic characteristics of the spindle tool system. Therefore, understanding the factors affecting dynamic behavior of a spindle tooling system is a prerequisite in dominating the final machining performance of machine tool system. To this purpose, a physical spindle unit was employed to assess the dynamic characteristics by vibration tests. Then, a three-dimensional finite element model of a high-speed spindle system integrated with tool holder was created to simulate the dynamic behaviors. For modeling the angular contact bearings, a series of spring elements were introduced between the inner and outer rings. The spring constant can be represented by the contact stiffness of the rolling bearing based on Hertz theory. The interface characteristic between spindle nose and tool holder taper can be quantified from the comparison of the measurements and predictions. According to the results obtained from experiments and finite element predictions, the vibration behavior of the spindle is dominated by the bending deformation of the spindle shaft in different modes, which is further determined by the stiffness of the bearings in spindle housing. Also, the spindle unit with tool holder shows a different dynamic behavior from that of spindle without tool holder. This indicates the interface property between tool holder and spindle nose plays an dominance on the dynamic characteristics the spindle tool system. Overall, the dynamic behaviors the spindle with and without tool holder can be successfully investigated through the finite element model proposed in this study. The prediction accuracy is determined by the modeling of the rolling interface of ball bearings in spindles and the interface characteristics between tool holder and spindle nose. Besides, identifications of the interface characteristics of a ball bearing and spindle tool holder are important for the refinement of the spindle tooling system to achieve the optimum machining performance.Keywords: contact stiffness, dynamic characteristics, spindle, tool holder interface
Procedia PDF Downloads 3001253 Investigation of Ameliorative Effect of a Polyphenolic Compound of Green Tea Extract against Rotenone Induced Neurotoxicity: A Mechanistic Approach
Authors: Sandeep Goyal, Sandeep Saluja
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Natural antioxidants have major role in maintenance of health. Green tea extract principally contains epigallocatechin-3-gallate (EGCG), as its abundant antioxidant constituent. Green tea is consumed daily worldwide as antioxidant to combat CNS diseases and has traditional importance also. EGCG has neuroprotective potential in various animal models of Parkinson disease, Alzheimer’s disease etc. but its exact mechanism has not been ruled out. The present study has been designed to investigate the anti-inflammatory, antioxidant and mitochondrial modulating mechanism of neuroprotective effect of epigallocatechin-3-gallate against rodent model of rotenone induced Parkinson’s disease (PD). The behavioural alterations were assessed by using open field test apparatus, Chatilon’s grip strength test apparatus and elevated plus maze for determining the locomotor activity, grip strength and cognition respectively. Biochemically, various parameters to assess oxidative stress, neuroinflammation and neurochemical estimations were performed on rat brain homogenates. A histological examination of rat brain striatum was done to check the neurodegeneration. Epigallocatechin-3-gallate (EGCG) at 10 & 20 mg/kg, were investigated for their neuroprotective potential along with levodopa as a standard agent. Minocycline, a microglial activation inhibitor, was administered alone and in combination with EGCG. EGCG and minocycline produced ameliorative effect against rotenone induced PD like symptoms by significantly reduced behavioral, biochemical and histological alterations. Results of our study reveal the neuroprotective effect of EGCG and minocycline against rotenone induced PD. Results of our study indicate that EGCG exerted neuroprotective effect against rotenone induced PD via its antioxidant, anti-inflammatory and mitochondrial modulating mechanisms and substantiate its previously reported and traditional claims for its use in CNS diseases.Keywords: antioxidants, neurotoxicity, rotenone, EGCG
Procedia PDF Downloads 3541252 Understanding Student Engagement through Sentiment Analytics of Response Times to Electronically Shared Feedback
Authors: Yaxin Bi, Peter Nicholl
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The rapid advancement of Information and communication technologies (ICT) is extremely influencing every aspect of Higher Education. It has transformed traditional teaching, learning, assessment and feedback into a new era of Digital Education. This also introduces many challenges in capturing and understanding student engagement with their studies in Higher Education. The School of Computing at Ulster University has developed a Feedback And Notification (FAN) Online tool that has been used to send students links to personalized feedback on their submitted assessments and record students’ frequency of review of the shared feedback as well as the speed of collection. The feedback that the students initially receive is via a personal email directing them through to the feedback via a URL link that maps to the feedback created by the academic marker. This feedback is typically a Word or PDF report including comments and the final mark for the work submitted approximately three weeks before. When the student clicks on the link, the student’s personal feedback is viewable in the browser and they can view the contents. The FAN tool provides the academic marker with a report that includes when and how often a student viewed the feedback via the link. This paper presents an investigation into student engagement through analyzing the interaction timestamps and frequency of review by the student. We have proposed an approach to modeling interaction timestamps and use sentiment classification techniques to analyze the data collected over the last five years for a set of modules. The data studied is across a number of final years and second-year modules in the School of Computing. The paper presents the details of quantitative analysis methods and describes further their interactions with the feedback overtime on each module studied. We have projected the students into different groups of engagement based on sentiment analysis results and then provide a suggestion of early targeted intervention for the set of students seen to be under-performing via our proposed model.Keywords: feedback, engagement, interaction modelling, sentiment analysis
Procedia PDF Downloads 1041251 A Modified Open Posterior Approach for the Fixation of Posterior Cruciate Ligament Tibial Avulsion Fractures
Authors: Babak Mirzashahi, Arvin Najafi, Pejman Mansouri, Mahmoud Farzan
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Background: The most effective treatment of posterior cruciate ligament (PCL) tears and the consequence of untreated PCL injuries remain controversial. Objectives: The aim of this study is to assess outcomes of fixation of tibial posterior cruciate ligament (PCL) avulsion fractures via a modified technique. Patients and Methods: From January, 2009 to March, 2012, there were 45 cases of PCL tibial avulsion fractures that were referred to our hospital and were managed through a modified open posterior approach. Fixation of Tibial PCL avulsion fractures were fixed by means of a lag screw and washer placed through our modified open posterior approach. Range of motion was begun on the first postoperative day. Clinical stability, range of motion, gastrocnemius muscle strength, radiographic investigation, and patient’s overall quality of life was analyzed at final follow up visit. Results: The average of overall musculoskeletal functional evaluation scores was 15 (range 3–35). All patients achieved union of their fracture and had clinically stable knees at the latest follow-up. The mean preoperative Lysholm score for 15 knees was 62 ± 8 (range, 50-75); the mean postoperative Lysholm score was 92± 7 (range, 75-101). A significant difference in Lysholm scores between preoperative and final follow-up evaluations was found (P < .05). At first-year follow-up, 42 (93%) patients revealed a difference of less than 10 mm in thigh circumference between their injured and healthy knees. Conclusions: The management of displaced large PCL avulsion fractures with placement of a cancellous lag screw with washer by means of the modified open posterior approach leads to satisfactory clinical, radiographic, and functional results and reduces the operation time and less blood loss. Level of evidence: IV.Keywords: posterior cruciate ligament, tibial fracture, lysholm knee score, patient outcome assessment
Procedia PDF Downloads 3021250 A Study of the Implications for the Health and Wellbeing of Energy-Efficient House Occupants: A UK-Based Investigation of Indoor Climate and Indoor Air Quality
Authors: Patricia Kermeci
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Policies related to the reduction of both carbon dioxide and energy consumption within the residential sector have contributed towards a growing number of energy-efficient houses being built in several countries. Many of these energy-efficient houses rely on the construction of very well insulated and highly airtight structures, ventilated mechanically. Although energy-efficient houses are indeed more energy efficient than conventional houses, concerns have been raised over the quality of their indoor air and, consequently, the possible adverse health and wellbeing effects for their occupants. Using a longitudinal study design over three different weather seasons (winter, spring and summer), this study has investigated the indoor climate and indoor air quality of different rooms (bedroom, living room and kitchen) in five energy-efficient houses and four conventional houses in the UK. Occupants have kept diaries of their activities during the studied periods and interviews have been conducted to investigate possible behavioural explanations for the findings. Data has been compared with reviews of epidemiological, toxicological and other health related published literature to reveals three main findings. First, it shows that the indoor environment quality of energy-efficient houses cannot be treated as a holistic entity as different rooms presented dissimilar indoor climate and indoor air quality. Thus, such differences might contribute to the health and wellbeing of occupants in different ways. Second, the results show that the indoor environment quality of energy-efficient houses can vary following changes in weather season, leaving occupants at a lower or higher risk of adverse health and wellbeing effects during different weather seasons. Third, one cannot assume that even identical energy-efficient houses provide a similar indoor environment quality. Fourth, the findings reveal that the practices and behaviours of the occupants of energy-efficient houses likely determine whether they enjoy a healthier indoor environment when compared with their control houses. In conclusion, it has been considered vital to understand occupants’ practices and behaviours in order to explain the ways they might contribute to the indoor climate and indoor air quality in energy-efficient houses.Keywords: energy-efficient house, health and wellbeing, indoor environment, indoor air quality
Procedia PDF Downloads 2331249 Investigation of Light Transmission Characteristics and CO2 Capture Potential of Microalgae Panel Bioreactors for Building Façade Applications
Authors: E. S. Umdu, Ilker Kahraman, Nurdan Yildirim, Levent Bilir
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Algae-culture offers new applications in sustainable architecture with its continuous productive cycle, and a potential for high carbon dioxide capture. Microalgae itself has multiple functions such as carbon dioxide fixation, biomass production, oxygen generation and waste water treatment. Incorporating microalgae cultivation processes and systems to building design to utilize this potential is promising. Microalgae cultivation systems, especially closed photo bioreactors can be implemented as components in buildings. And these systems be accommodated in the façade of a building, or in other urban infrastructure in the future. Application microalgae bio-reactors of on building’s façade has the added benefit of acting as an effective insulation system, keeping out the heat of the summer and the chill of the winter. Furthermore, microalgae can give a dynamic appearance with a liquid façade that also works as an adaptive sunshade. Recently, potential of microalgae to use as a building component to reduce net energy demand in buildings becomes a popular topic and innovative design proposals and a handful of pilot applications appeared. Yet there is only a handful of examples in application and even less information on how these systems affect building energy behavior. Further studies on microalgae mostly focused on single application approach targeting either carbon dioxide utilization through biomass production or biofuel production. The main objective of this study is to investigate effects of design parameters of microalgae panel bio-reactors on light transmission characteristics and CO2 capture potential during growth of Nannochloropsis occulata sp. A maximum reduction of 18 ppm in CO2 levels of input air during the experiments with a % light transmission of 14.10, was achieved in 6 day growth cycles. Heat transfer behavior during these cycles was also inspected for possible façade applications.Keywords: building façade, CO2 capture, light transmittance, microalgae
Procedia PDF Downloads 1931248 Mapping Consumer Role: A Systematic Review of Circular Economy Strategies
Authors: Kiana Keshavarz, Carmen Jaca, María J. Álvarez
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The shift to a circular economy necessitates a substantial change in consumer behavior, a complex and unpredictable actor that proves challenging to guide toward sustainability. This systematic literature review addresses the pivotal role that consumers play in propelling a circular economy, emphasizing the critical gap between positive attitudes and responsible actions. In this review, we utilized two prominent databases, Scopus and Web of Science, during the months of July and August 2023. A comprehensive screening process considered 467 articles, ultimately including 115 in the study for detailed analysis. Recognizing the transformative potential of consumer behavior, the study examines three key phases of consumer interaction with products —pre-purchasing decision, careful usage, and post-use management—identifying consumer-centric strategies that boost sustainability in each phase. Contrary to the prevailing emphasis on post-management strategies in society, the synthesis highlights the profound impact of strategies enacted during the pre-purchasing decision phase. In the investigation of the persistent attitude-behavior gap, factors influencing this gap and impeding consumers from engaging in sustainable actions are identified based on behavioral theories. Subsequently, strategies aimed at diminishing barriers and boosting motivators, as outlined in the literature, are presented. Recognizing the transformative potential of consumer behavior, the study underscores the pivotal roles of policymakers, businesses, and governments in fostering a more sustainable future. Ultimately, there is a call for further research to enhance the depth of analysis. This could be achieved through a more focused approach, such as narrowing the scope to a specific industry or applying a specific behavioral theory.Keywords: circular economy, consumer behavior, sustainability, attitude-behavior gap, systematic literature review
Procedia PDF Downloads 811247 The Anti-Glycation Effect of Sclerocarya birrea Stem-Bark Extracts and Their Ability to Break Existing Advanced Glycation End-Products Protein Cross-Links
Authors: O. I. Adeniran, M. A. Mogale
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Advanced glycation end-products (AGEs) have been implicated in the development and progression of vascular complications of diabetes mellitus and other age-related disease such as Alzheimer’s disease, heart diseases, stroke and limb amputation. The aim of the study was to determine the anti-glycation activity and AGE-cross-linking breaking ability of Sclerocarya birrea stem-bark extracts (SBSBETs). Hexane, ethyl acetate, methanol and water extracts of Sclerocarya birrea stem-bark and standard inhibitor, aminoguanidine (AG) were incubated with bovine serum albumin (BSA)-fructose mixture for 20 and 40 days. The amounts of total immunogenic AGEs (TIAGEs), fluorescent AGEs (FAGEs) and carboxymethyl lysine (CML) formed were determined and the percentage anti-glycation activity of each plant extract calculated. The ability of SBSBETs to break fructose-derived BSA-AGE-collagen cross-links was also investigated. All SBSBETs under investigation demonstrated less anti-glycation activity against TIAGE, FAGEs and CML than AG after 20 days incubation. After 40 days incubation, ethyl acetate, methanol and water SBSBETs demonstrated lower anti-glycation activity against TIAGEs than AG but exerted higher anti-glycation activity than AG against FAGEs. All SBSBETs except water demonstrated lower anti-glycation activity than AG against CML. With regard to the ability of SBSBETs to breakdown fructose-derived AGEs cross-links, the polar SBSBETs demonstrated higher ability to break AGE-cross-links than the non-polar ones. The results of this study may lead to the isolation of bio-active phyto-chemicals from SBSBETs that may be used for the prevention of vascular complication of diabetes.Keywords: advanced glycation end-products, anti-glycation, cross-link breaking, Sclerocarrya birrea
Procedia PDF Downloads 2641246 Empirical Analysis of Forensic Accounting Practices for Tackling Persistent Fraud and Financial Irregularities in the Nigerian Public Sector
Authors: Sani AbdulRahman Bala
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This empirical study delves into the realm of forensic accounting practices within the Nigerian Public Sector, seeking to quantitatively analyze their efficacy in addressing the persistent challenges of fraud and financial irregularities. With a focus on empirical data, this research employs a robust methodology to assess the current state of fraud in the Nigerian Public Sector and evaluate the performance of existing forensic accounting measures. Through quantitative analyses, including statistical models and data-driven insights, the study aims to identify patterns, trends, and correlations associated with fraudulent activities. The research objectives include scrutinizing documented fraud cases, examining the effectiveness of established forensic accounting practices, and proposing data-driven strategies for enhancing fraud detection and prevention. Leveraging quantitative methodologies, the study seeks to measure the impact of technological advancements on forensic accounting accuracy and efficiency. Additionally, the research explores collaborative mechanisms among government agencies, regulatory bodies, and the private sector by quantifying the effects of information sharing on fraud prevention. The empirical findings from this study are expected to provide a nuanced understanding of the challenges and opportunities in combating fraud within the Nigerian Public Sector. The quantitative insights derived from real-world data will contribute to the refinement of forensic accounting strategies, ensuring their effectiveness in addressing the unique complexities of financial irregularities in the public sector. The study's outcomes aim to inform policymakers, practitioners, and stakeholders, fostering evidence-based decision-making and proactive measures for a more resilient and fraud-resistant financial governance system in Nigeria.Keywords: fraud, financial irregularities, nigerian public sector, quantitative investigation
Procedia PDF Downloads 641245 Development and Investigation of Efficient Substrate Feeding and Dissolved Oxygen Control Algorithms for Scale-Up of Recombinant E. coli Cultivation Process
Authors: Vytautas Galvanauskas, Rimvydas Simutis, Donatas Levisauskas, Vykantas Grincas, Renaldas Urniezius
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The paper deals with model-based development and implementation of efficient control strategies for recombinant protein synthesis in fed-batch E.coli cultivation processes. Based on experimental data, a kinetic dynamic model for cultivation process was developed. This model was used to determine substrate feeding strategies during the cultivation. The proposed feeding strategy consists of two phases – biomass growth phase and recombinant protein production phase. In the first process phase, substrate-limited process is recommended when the specific growth rate of biomass is about 90-95% of its maximum value. This ensures reduction of glucose concentration in the medium, improves process repeatability, reduces the development of secondary metabolites and other unwanted by-products. The substrate limitation can be enhanced to satisfy restriction on maximum oxygen transfer rate in the bioreactor and to guarantee necessary dissolved carbon dioxide concentration in culture media. In the recombinant protein production phase, the level of substrate limitation and specific growth rate are selected within the range to enable optimal target protein synthesis rate. To account for complex process dynamics, to efficiently exploit the oxygen transfer capability of the bioreactor, and to maintain the required dissolved oxygen concentration, adaptive control algorithms for dissolved oxygen control have been proposed. The developed model-based control strategies are useful in scale-up of cultivation processes and accelerate implementation of innovative biotechnological processes for industrial applications.Keywords: adaptive algorithms, model-based control, recombinant E. coli, scale-up of bioprocesses
Procedia PDF Downloads 2581244 Technology Futures in Global Militaries: A Forecasting Method Using Abstraction Hierarchies
Authors: Mark Andrew
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Geopolitical tensions are at a thirty-year high, and the pace of technological innovation is driving asymmetry in force capabilities between nation states and between non-state actors. Technology futures are a vital component of defence capability growth, and investments in technology futures need to be informed by accurate and reliable forecasts of the options for ‘systems of systems’ innovation, development, and deployment. This paper describes a method for forecasting technology futures developed through an analysis of four key systems’ development stages, namely: technology domain categorisation, scanning results examining novel systems’ signals and signs, potential system-of systems’ implications in warfare theatres, and political ramifications in terms of funding and development priorities. The method has been applied to several technology domains, including physical systems (e.g., nano weapons, loitering munitions, inflight charging, and hypersonic missiles), biological systems (e.g., molecular virus weaponry, genetic engineering, brain-computer interfaces, and trans-human augmentation), and information systems (e.g., sensor technologies supporting situation awareness, cyber-driven social attacks, and goal-specification challenges to proliferation and alliance testing). Although the current application of the method has been team-centred using paper-based rapid prototyping and iteration, the application of autonomous language models (such as GPT-3) is anticipated as a next-stage operating platform. The importance of forecasting accuracy and reliability is considered a vital element in guiding technology development to afford stronger contingencies as ideological changes are forecast to expand threats to ecology and earth systems, possibly eclipsing the traditional vulnerabilities of nation states. The early results from the method will be subjected to ground truthing using longitudinal investigation.Keywords: forecasting, technology futures, uncertainty, complexity
Procedia PDF Downloads 1161243 Estimation of Radon (²²²Rn) Activity Concentration Levels and Associated Effective Dose in Bottled Drinking Water from South Africa
Authors: Samuel Odumu Ogana John, Stephen Friday Olukotun, Manny Mathuthu
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Radon-222 (²²²Rn), a naturally occurring radioactive gas, poses potential health risks due to its inhalation and ingestion, especially through drinking water. This study investigates the activity concentration levels of ²²²Rn in 21 brands of bottled water samples collected from the open market in South Africa. The samples were analyzed using a highly sensitive system consisting of the Ionization Chamber AlphaGUARD (PQ 2000), an AquaKIT set, and an AlphaPUMP, ensuring precise measurement of radon activity. The results revealed significant variations in radon concentrations across different brands, with values ranging from 0.062 ± 0.046 Bq/m³ to 0.198 ± 0.286 Bq/mv³, with a mean of 0.118 ± 0.034 Bq/m³. These measurements were then used to estimate the annual effective ingestion dose of radiation for consumers across various age groups based on the guidelines provided by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The mean effective doses were found to be 4.057 × 10⁻⁴ ± 1.188 × 10⁻⁴ mSv/y for infants (1–2 years), 2.428 × 10⁻⁴ ± 7.111 × 10⁻⁵ mSv/y for children (7–12 years), and 2.058 × 10⁻⁴ ± 6.026 × 10⁻⁵ mSv/y for adults, all of which are below the recommended international safety limits and are comparable to other published studies. These findings suggest that bottled drinking water in South Africa is safe for consumption and does not pose a significant health hazard from ²²²Rn radiation. The study underscores the importance of monitoring radon levels in bottled water to assess the associated radiological health risks, particularly in South Africa, where access to safe drinking water is essential. This research provides baseline data for future regulatory frameworks and policy development and can serve as a valuable reference for bottled water producers. Furthermore, it highlights the need for continued investigation into the regulation and mitigation of radon exposure in drinking water sources throughout the country.Keywords: Radon-222, activity concentration levels, annual effective ingestion dose, bottled drinking water, South Africa
Procedia PDF Downloads 71242 Design and Emotion: The Value of 1970s French Children’s Books in the Middle East
Authors: Tina Sleiman
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In the early 1970s, a graphics revolution - in quantity and quality - marked the youth publications sector in France. The increased interest in youth publications was supported with the emergence of youth libraries and major publishing houses. In parallel, the 'Agence de Cooperation Culturelle et Technique' (currently the International Organization of the Francophonie) was created, and several Arab countries had joined as members. In spite of political turmoil in the Middle East, French schools in Arab countries were still functioning and some even flourishing. This is a testament that French culture was, and still is, a major export to the region. This study focuses on the aesthetic value of the graphic styles that characterize French children’s books from the 1970s, and their personal value to Francophone people who have consumed these artifacts, in the Middle East. The first part of the study looks at the artifact itself: starting from the context of creation and consumption of these books, and continuing to the preservation and remaining collections. The aesthetic value is studied and compared to similar types of visuals of juxtaposed time periods. The second part examines the audience’s response to the visuals in terms of style recognition or identification, along with emotional significance or associations, and the personal value the artifacts might hold to their consumers. The methods of investigation consist of a literature review, a survey of book collections, and a visual questionnaire, supported by personal interviews. As an outcome, visual patterns will be identified: elements from 1970s children’s books reborn in contemporary youth-based publications. Results of the study shall inform us directly on the aesthetic and personal value of illustrated French children’s books in the Middle East, and indirectly on the capacity of youth-targeted design to create a long-term emotional response from its audience.Keywords: children’s books, French visual culture, graphic style, publication design, revival
Procedia PDF Downloads 1711241 A Case Study on Performance of Isolated Bridges under Near-Fault Ground Motion
Authors: Daniele Losanno, H. A. Hadad, Giorgio Serino
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This paper presents a numerical investigation on the seismic performance of a benchmark bridge with different optimal isolation systems under near fault ground motion. Usually, very large displacements make seismic isolation an unfeasible solution due to boundary conditions, especially in case of existing bridges or high risk seismic regions. Hence, near-fault ground motions are most likely to affect either structures with long natural period range like isolated structures or structures sensitive to velocity content such as viscously damped structures. The work is aimed at analyzing the seismic performance of a three-span continuous bridge designed with different isolation systems having different levels of damping. The case study was analyzed in different configurations including: (a) simply supported, (b) isolated with lead rubber bearings (LRBs), (c) isolated with rubber isolators and 10% classical damping (HDLRBs), and (d) isolated with rubber isolators and 70% supplemental damping ratio. Case (d) represents an alternative control strategy that combines the effect of seismic isolation with additional supplemental damping trying to take advantages from both solutions. The bridge is modeled in SAP2000 and solved by time history direct-integration analyses under a set of six recorded near-fault ground motions. In addition to this, a set of analysis under Italian code provided seismic action is also conducted, in order to evaluate the effectiveness of the suggested optimal control strategies under far field seismic action. Results of the analysis demonstrated that an isolated bridge equipped with HDLRBs and a total equivalent damping ratio of 70% represents a very effective design solution for both mitigation of displacement demand at the isolation level and base shear reduction in the piers also in case of near fault ground motion.Keywords: isolated bridges, near-fault motion, seismic response, supplemental damping, optimal design
Procedia PDF Downloads 2871240 Quantification of Global Cerebrovascular Reactivity in the Principal Feeding Arteries of the Human Brain
Authors: Ravinder Kaur
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Introduction Global cerebrovascular reactivity (CVR) mapping is a promising clinical assessment for stress-testing the brain using physiological challenges, such as CO₂, to elicit changes in perfusion. It enables real-time assessment of cerebrovascular integrity and health. Conventional imaging approaches solely use steady-state parameters, like cerebral blood flow (CBF), to evaluate the integrity of the resting parenchyma and can erroneously show a healthy brain at rest, despite the underlying pathogenesis in the presence of cerebrovascular disease. Conversely, coupling CO₂ inhalation with phase-contrast MRI neuroimaging interrogates the capacity of the vasculature to respond to changes under stress. It shows promise in providing prognostic value as a novel health marker to measure neurovascular function in disease and to detect early brain vasculature dysfunction. Objective This exploratory study was established to:(a) quantify the CBF response to CO₂ in hypocapnia and hypercapnia,(b) evaluate disparities in CVR between internal carotid (ICA) and vertebral artery (VA), and (c) assess sex-specific variation in CVR. Methodology Phase-contrast MRI was employed to measure the cerebrovascular reactivity to CO₂ (±10 mmHg). The respiratory interventions were presented using the prospectively end-tidal targeting RespirActTM Gen3 system. Post-processing and statistical analysis were conducted. Results In 9 young, healthy subjects, the CBF increased from hypocapnia to hypercapnia in all vessels (4.21±0.76 to 7.20±1.83 mL/sec in ICA, 1.36±0.55 to 2.33±1.31 mL/sec in VA, p < 0.05). The CVR was quantitatively higher in ICA than VA (slope of linear regression: 0.23 vs. 0.07 mL/sec/mmHg, p < 0.05). No statistically significant effect was observed in CVR between male and female (0.25 vs 0.20 mL/sec/mmHg in ICA, 0.09 vs 0.11 mL/sec/mmHg in VA, p > 0.05). Conclusions The principal finding in this investigation validated the modulation of CBF by CO₂. Moreover, it has indicated that regional heterogeneity in hemodynamic response exists in the brain. This study provides scope to standardize the quantification of CVR prior to its clinical translation.Keywords: cerebrovascular disease, neuroimaging, phase contrast MRI, cerebrovascular reactivity, carbon dioxide
Procedia PDF Downloads 1521239 Exploring Attachment Mechanisms of Sulfate-Reducing Bacteria Biofilm to X52 Carbon Steel and Effective Mitigation Through Moringa Oleifera Extract
Authors: Hadjer Didouh, Mohammed Hadj Melliani, Izzeddine Sameut Bouhaik
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Corrosion is a serious problem in industrial installations or metallic transport pipes. Corrosion is an interfacial process controlled by several parameters. The presence of microorganisms affects the kinetics of corrosion. This type of corrosion is often referred as bio-corrosion or corrosion influenced by microorganisms (MIC). The action of a microorganism or a bacterium is carried out by the formation of biofilm following its attachment to the metal surface. The formation of biofilm isolates the metal surface from its environment and allows the bacteria to control the parameters of the metal/bacteria interface. Biofilm formation by sulfate-reducing bacteria (SRB) X52 steel, poses substantial challenges in oil and gas industry SONATRACH of Algeria. This research delves into the complex attachment mechanisms employed by SRB biofilm on X52 carbon steel and investigates strategies for effective mitigation using biocides. The exploration commences by elucidating the underlying mechanisms facilitating SRB biofilm adhesion to X52 carbon steel, considering factors such as surface morphology, electrostatic interactions, and microbial extracellular substances. Advanced microscopy and spectroscopic techniques provide a support to the attachment processes, laying the foundation for targeted mitigation strategies. The use of 100 ppm of Moringa Oleifera extract biocide as a promising approach to control and prevent SRB biofilm formation on X52 carbon steel surfaces. Green extract undergo evaluation for their effectiveness in disrupting biofilm development while ensuring the integrity of the steel substrate. Systematic analysis is conducted on the biocide's impact on the biofilm's structural integrity, microbial viability, and overall attachment strength. This two-pronged investigation aims to deepen our comprehension of SRB biofilm dynamics and contribute to the development of effective strategies for mitigating its impact on X52 carbon steel.Keywords: bio-corrosion, biofilm, attachement, metal/bacteria interface
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