Search results for: temporal variation
779 Design, Modeling, Fabrication, and Testing of a Scaled down Hybrid Rocket Engine
Authors: Pawthawala Nancy Manish, Syed Alay Hashim
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A hybrid rocket is a rocket engine which uses propellants in two different states of matter- one is in solid and the other either gas or liquid. A hybrid rocket exhibit advantages over both liquid rockets and solid rockets especially in terms of simplicity, stop-start-restart capabilities, safety and cost. This paper deals the design and development of a hybrid rocket having paraffin wax as solid fuel and liquid oxygen as oxidizer. Due to variation of pressure in combustion chamber there is significantly change in mass flow rate, burning rate and uneven regression along the length of the grain. This project describes the working model of a hybrid propellant rocket motor. We have designed a hybrid rocket thrust chamber based on the predetermined combustion chamber pressure and the properties of hybrid propellant. This project is all ready in working condition with normal oxygen injector. Now we have planned to modify the injector design to improve the combustion property. We will use spray type injector for injecting the oxidizer. This idea will increase the performance followed by the regression rate of the solid fuel. By employing mass conservation law, oxygen mass flux, oxidizer/fuel ratio and regression rate the thrust coefficient can be obtained for our current design. CATIA V5 R20 is our design software for the complete setup. This project is fully based on experimental evaluation and the collection of combustion and flow parameters. The thrust chamber is made of stainless steel and the duration of test is around 15-20 seconds (Maximum). These experiments indicates that paraffin based fuel provides the opportunity to satisfy a broad range of mission requirements for the next generation of the hybrid rocket system.Keywords: burning rate, liquid oxygen, mass flow rate, paraffin wax and sugar
Procedia PDF Downloads 329778 STD-NMR Based Protein Engineering of the Unique Arylpropionate-Racemase AMDase G74C
Authors: Sarah Gaßmeyer, Nadine Hülsemann, Raphael Stoll, Kenji Miyamoto, Robert Kourist
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Enzymatic racemization allows the smooth interconversion of stereocenters under very mild reaction conditions. Racemases find frequent applications in deracemization and dynamic kinetic resolutions. Arylmalonate decarboxylase (AMDase) from Bordetella Bronchiseptica has high structural similarity to amino acid racemases. These cofactor-free racemases are able to break chemically strong CH-bonds under mild conditions. The racemase-like catalytic machinery of mutant G74C conveys it a unique activity in the racemisation of pharmacologically relevant derivates of 2-phenylpropionic acid (profenes), which makes AMDase G74C an interesting object for the mechanistic investigation of cofactor-independent racemases. Structure-guided protein engineering achieved a variant of this unique racemase with 40-fold increased activity in the racemisation of several arylaliphatic carboxylic acids. By saturation–transfer–difference NMR spectroscopy (STD-NMR), substrate binding during catalysis was investigated. All atoms of the substrate showed interactions with the enzyme. STD-NMR measurements revealed distinct nuclear Overhauser effects in experiments with and without molecular conversion. The spectroscopic analysis led to the identification of several amino acid residues whose variation increased the activity of G74C. While single-amino acid exchanges increased the activity moderately, structure-guided saturation mutagenesis yielded a quadruple mutant with a 40 times higher reaction rate. This study presents STD-NMR as versatile tool for the analysis of enzyme-substrate interactions in catalytically competent systems and for the guidance of protein engineering.Keywords: racemase, rational protein design, STD-NMR, structure guided saturation mutagenesis
Procedia PDF Downloads 299777 The Dynamic of Nₘᵢₙ in Clay Loam Cambisol in Alternative Farming
Authors: Danute Jablonskyte-Rasce, Laura Masilionyte
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The field experiments of different farming systems were conducted at Joniškėlis Experimental Station of the Lithuanian Research Centre for Agriculture and Forestry in 2006–2016. The soil of the experimental site was Endocalcari-Endohypogleyic Cambisol (CMg-n-w-can). The research was designed to identify the effects of dry matter and nitrogen accumulated in the above-ground biomass of various catch crops grown after winter wheat on soil mineral nitrogen variation during the autumn and spring period in the presence of intensive leaching complex. Research was done in the soil differing in humus status in the organic and sustainable cropping systems by growing various plant mixtures as catch crops: narrow-leafed lupine (Lupinus angustifolius L.) and oil radish (Raphanus sativus var. Oleifera L.), white mustard (Sinapis alba L.) and buckwheat (Fagopyrum exculentum Moench.) and white mustard as a sole crop. All crop and soil management practices have shown optimal efficiency in late autumn – stubble breaking, catch crops and straw used during the post-harvest period of the main crops, reduced Nmin migration into deeper (40–80 cm) soil layer. The greatest Nmin reduction in the 0–40 cm soil layer during the period from late autumn to early spring was identified in the sustainable cropping system having applied N30 for the promotion of straw mineralization and with no catch crops cultivation. The sustainable cropping system, having applied N30 for straw mineralization and growing white mustard in combination with buckwheat as catch crops, Nmin difference in the spring compared with its status in the autumn in the soil low and moderate in humus was lower by 70.1% and 34.2%, respectively.Keywords: soil nitrogen, catch crops, ecological and sustainable farming systems, Cambisol
Procedia PDF Downloads 254776 Modeling Landscape Performance: Evaluating the Performance Benefits of the Olmsted Brothers’ Proposed Parkway Designs for Los Angeles
Authors: Aaron Liggett
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This research focuses on the visionary proposal made by the Olmsted Brothers Landscape Architecture firm in the 1920s for a network of interconnected parkways in Los Angeles. Their envisioned parkways aimed to address environmental and cultural strains by providing green space for recreation, wildlife habitat, and stormwater management while serving as multimodal transportation routes. Although the parkways were never constructed, through an evidence-based approach, this research presents a framework for evaluating the potential functionality and success of the parkways by modeling and visualizing their quantitative and qualitative landscape performance and benefits. Historical documents and innovative digital modeling tools produce detailed analysis, modeling, and visualization of the parkway designs. A set of 1928 construction documents are used to analyze and interpret the design intent of the parkways. Grading plans are digitized in CAD and modeled in Sketchup to produce 3D visualizations of the parkway. Drainage plans are digitized to model stormwater performance. Planting plans are analyzed to model urban forestry and biodiversity. The EPA's Storm Water Management Model (SWMM) predicts runoff quantity and quality. The USDA Forests Service tools evaluate carbon sequestration and air quality. Spatial and overlay analysis techniques are employed to assess urban connectivity and the spatial impacts of the parkway designs. The study reveals how the integration of blue infrastructure, green infrastructure, and transportation infrastructure within the parkway design creates a multifunctional landscape capable of offering alternative spatial and temporal uses. The analysis demonstrates the potential for multiple functional, ecological, aesthetic, and social benefits to be derived from the proposed parkways. The analysis of the Olmsted Brothers' proposed Los Angeles parkways, which predated contemporary ecological design and resiliency practices, demonstrates the potential for providing multiple functional, ecological, aesthetic, and social benefits within urban designs. The findings highlight the importance of integrated blue, green, and transportation infrastructure in creating a multifunctional landscape that simultaneously serves multiple purposes. The research contributes new methods for modeling and visualizing landscape performance benefits, providing insights and techniques for informing future designs and sustainable development strategies.Keywords: landscape architecture, ecological urban design, greenway, landscape performance
Procedia PDF Downloads 121775 Modeling and Simulation of Turbulence Induced in Nozzle Cavitation and Its Effects on Internal Flow in a High Torque Low Speed Diesel Engine
Authors: Ali Javaid, Rizwan Latif, Syed Adnan Qasim, Imran Shafi
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To control combustion inside a direct injection diesel engine, fuel atomization is the best tool. Controlling combustion helps in reducing emissions and improves efficiency. Cavitation is one of the most important factors that significantly affect the nature of spray before it injects into combustion chamber. Typical fuel injector nozzles are small and operate at a very high pressure, which limits the study of internal nozzle behavior especially in case of diesel engine. Simulating cavitation in a fuel injector will help in understanding the phenomenon and will assist in further development. There is a parametric variation between high speed and high torque low speed diesel engines. The objective of this study is to simulate internal spray characteristics for a low speed high torque diesel engine. In-nozzle cavitation has strong effects on the parameters e.g. mass flow rate, fuel velocity, and momentum flux of fuel that is to be injected into the combustion chamber. The external spray dynamics and subsequently the air – fuel mixing depends on a lot of the parameters of fuel injecting the nozzle. The approach used to model turbulence induced in – nozzle cavitation for high-torque low-speed diesel engine, is homogeneous equilibrium model. The governing equations were modeled using Matlab. Complete Model in question was extensively evaluated by performing 3-D time-dependent simulations on Open FOAM, which is an open source flow solver and implemented in CFD (Computational Fluid Dynamics). Results thus obtained will be analyzed for better evaporation in the near-nozzle region. The proposed analyses will further help in better engine efficiency, low emission, and improved fuel economy.Keywords: cavitation, HEM model, nozzle flow, open foam, turbulence
Procedia PDF Downloads 278774 Pretherapy Initial Dosimetry Results in Prostat Cancer Radionuclide Therapy with Lu-177-PSMA-DOTA-617
Authors: M. Abuqebitah, H. Tanyildizi, N. Yeyin, I. Cavdar, M. Demir, L. Kabasakal
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Aim: Targeted radionuclide therapy (TRT) is an increasingly used treatment modality for wide range of cancers. Presently dosimetry is highly required either to plan treatment or to ascertain the absorbed dose delivered to critical organs during treatment. Methods and Materials: The study comprised 7 patients suffered from prostate cancer with progressive disease and candidate to undergo Lu-177-DOTA-617 therapy following to PSMA- PET/CT imaging for all patients. (5.2±0.3 mCi) was intravenously injected. To evaluate bone marrow absorbed dose 2 cc blood samples were withdrawn in short variable times (3, 15, 30, 60, 180 minutes) after injection. Furthermore, whole body scans were performed using scintillation gama camera in 4, 24, 48, and 120 hours after injection and in order to quantify the activity taken up in the body, kidneys , liver, right parotid, and left parotid the geometric mean of anterior and posterior counts were determined through ROI analysis, after that background subtraction and attenuation correction were applied using patients PSMA- PET/CT images taking in a consideration: organ thickness, body thickness, and Hounsfield unites from CT scan. OLINDA/EXM dosimetry program was used for curve fitting, residence time calculation, and absorbed dose calculations. Findings: Absorbed doses of bone marrow, left kidney, right kidney, liver, left parotid, right parotid, total body were 1.28±0.52, 32.36±16.36, 32.7±13.68, 10.35±3.45, 38.67±21.29, 37.55±19.77, 2.25±0.95 (mGy/mCi), respectively. Conclusion: Our first results clarify that Lu-177-DOTA-617 is safe and reliable therapy as there were no complications seen. In the other hand, the observable variation in the absorbed dose of the critical organs among the patients necessitate patient-specific dosimetry approach to save body organs and particularly highly exposed kidneys and parotid gland.Keywords: Lu-177-PSMA, prostate cancer, radionuclide therapy
Procedia PDF Downloads 472773 Finite Element Analysis for Earing Prediction Incorporating the BBC2003 Material Model with Fully Implicit Integration Method: Derivation and Numerical Algorithm
Authors: Sajjad Izadpanah, Seyed Hadi Ghaderi, Morteza Sayah Irani, Mahdi Gerdooei
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In this research work, a sophisticated yield criterion known as BBC2003, capable of describing planar anisotropic behaviors of aluminum alloy sheets, was integrated into the commercial finite element code ABAQUS/Standard via a user subroutine. The complete formulation of the implementation process using a fully implicit integration scheme, i.e., the classic backward Euler method, is presented, and relevant aspects of the yield criterion are introduced. In order to solve nonlinear differential and algebraic equations, the line-search algorithm was adopted in the user-defined material subroutine (UMAT) to expand the convergence domain of the iterative Newton-Raphson method. The developed subroutine was used to simulate a challenging computational problem with complex stress states, i.e., deep drawing of an anisotropic aluminum alloy AA3105. The accuracy and stability of the developed subroutine were confirmed by comparing the numerically predicted earing and thickness variation profiles with the experimental results, which showed an excellent agreement between numerical and experimental earing and thickness profiles. The integration of the BBC2003 yield criterion into ABAQUS/Standard represents a significant contribution to the field of computational mechanics and provides a useful tool for analyzing the mechanical behavior of anisotropic materials subjected to complex loading conditions.Keywords: BBC2003 yield function, plastic anisotropy, fully implicit integration scheme, line search algorithm, explicit and implicit integration schemes
Procedia PDF Downloads 68772 Mechanical Properties Analysis of Masonry Residue Mortar as Cement Replacement
Authors: Camila Parodi, Viviana Letelier, Giacomo Moriconi
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The cement industry is responsible for around a 5% of the CO2 emissions worldwide and considering that concrete is one of the most used materials in construction its total effect is important. An alternative to reduce the environmental impact of concrete production is to incorporate certain amount of residues in the dosing, limiting the replacement percentages to avoid significant losses in the mechanical properties of the final material. Previous researches demonstrate the feasibility of using brick and rust residues, separately, as a cement replacement. This study analyses the variation in the mechanical properties of mortars by incorporating masonry residue composed of clay bricks and cement mortar. In order to improve the mechanical properties of masonry residue, this was subjected to a heat treatment of 650 ° C for four hours and its effect is analyzed in this study. Masonry residue was obtained from a demolition of masonry perimetral walls. The residues were crushed and sieved and the maximum size of particles used was 75 microns. The percentages of cement replaced by masonry residue were 0%, 10%, 20% and 30%. The effect of masonry residue addition and its heat treatment in the mechanical properties of mortars is evaluated through compressive and flexural strength tests after 7, 14 and 28 curing days. Results show that increasing the amount of masonry residue used increases the losses in compressive strength and flexural strength. However, the use of up to a 20% of masonry residue, when a heat treatment is applied, allows obtaining mortars with similar compressive strength to the control mortar. Masonry residues mortars without a heat treatment show losses in compressive strengths between 15% and 27% with respect to masonry residues with heat treatment, which demonstrates the effectiveness of the heat treatment. From this analysis it can be conclude that it is possible to use up to 20% of masonry residue with heat treatment as cement replacement without significant losses in mortars mechanical properties, reducing considerably the environmental impact of the final material.Keywords: cement replacement, environmental impact, masonry residue, mechanical properties of recycled mortars
Procedia PDF Downloads 379771 Resistance to the South African Root-Knot Nematode Population Densities in Artemisia annua: An Anti-Malaria Ethnomedicinal Plant
Authors: Kgabo Pofu, Hintsa Araya, Dean Oelofse, Sonja Venter, Christian Du Plooy, Phatu Mashela
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Nematode resistance to the tropical root-knot (Meloidogyne species) nematodes is one of the most preferred nematode management strategies in development of smallholder resource-poor farming systems. Due to its pharmacological and ethnomedicinal applications, Artemisia annua is one of the underutilised crops that have attracted attention of policy-makers in rural agrarian development in South Africa. However, the successful introduction of this crop in smallholder resource-poor farming systems could be upset by the widespread aggressive Meloidogyne species, which have limited management options. The objective of this study therefore was to determine the degree of nematode resistance to the South African M. incognita and M. javanica population densities on A. annua seedlings. Uniform three-week-old seedlings in pots containing pasteurised growing medium under greenhouse conditions were inoculated using a series of eggs and second-stage juveniles of two Meloidogyne species in separate trials. At 56 days after inoculation, treatments were highly significant on reproductive factor (RF) for M. incognita and M. javanica on A. annua, contributing 87 and 89% in total treatment variation of the variables, respectively. At all levels of inoculation, RF values for M. incognita (0.17-0.79) and M. javanica (0.02-0.29) were below unity, without any noticeable root galls. Infection of A. annua by both Meloidogyne species had no significant effects on growth variables. In conclusion, A. annua seedlings are resistant to the South African M. incognita and M. javanica population densities and could therefore be explored further for use in smallholder resource-poor farming systems.Keywords: ethnomedicial plants, medicinal plants, underutilised crops, plant parasitic nematodes
Procedia PDF Downloads 297770 Factors Affecting Contractual Disputes in Construction ProJects in Sri Lanka
Authors: R. M. Rajapaksa
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Construction industry is one of the key players in driving the economy of a country to achieve its prosperity. However, a dispute is one of the crucial factors which prevent the completion of construction contracts within the budgeted cost, scheduled time, and accepted quality. Disputes are inevitable in the construction contract. Accordingly, a study has been undertaken to identify the factors affecting contractual disputes in construction projects in Sri Lanka. The study was a mixed approach with major qualitative and minor quantitative. Qualitative study was set in the form of in-depth interviews with eighteen participants, and quantitative study was conducted using a questionnaire with twenty-four respondents from previously implemented projects by the National Water Supply & Drainage Board representing the employer, engineer and the Contractor to identify the factors affecting contractual disputes and to verify most critical factors respectively. Data analysis for qualitative and quantitative studies was carried out by means of transcribing, code & categorizeand average score methods, respectively. The study reveals that there are forty factors affecting the contractual disputes in construction contracts in Sri Lanka. The finding further illustrates that conflicting decisions by inexperience personnel in the higher position of the Employer, ambiguities resulting inadequate descriptions of the preliminary/general items in price schedule, unfair valuation and late confirmation of variations, unfair determination due to lack of experience of the Engineer/Consultant, under certification of progress payments, unfair grant of EOT & application of delay damages, unreasonable claims for variation of works, errors/discrepancies/ambiguities in the contract conditions and discrepancies & errors in designs & specifications are the most critical factors affecting contractual disputes. Finally, the study proposed remedial measures to most critical factors affecting contractual disputes.Keywords: dispute, contractual, factors, employer, engineer, contractor, construction projects
Procedia PDF Downloads 207769 Designing Online Professional Development Courses Using Video-Based Instruction to Teach Robotics and Computer Science
Authors: Alaina Caulkett, Audra Selkowitz, Lauren Harter, Aimee DeFoe
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Educational robotics is an effective tool for teaching and learning STEM curricula. Yet, most traditional professional development programs do not cover engineering, coding, or robotics. This paper will give an overview of how and why the VEX Professional Development Plus Introductory Training courses were developed to provide guided, simple professional development in the area of robotics and computer science instruction. These training courses guide educators through learning the basics of VEX robotics platforms, including VEX 123, GO, IQ, and EXP. Because many educators do not have experience teaching robotics or computer science, this course is meant to simulate one on one training or tutoring through video-based instruction. These videos, led by education professionals, can be watched at any time, which allows educators to watch at their own pace and create their own personalized professional development timeline. This personalization expands beyond the course itself into an online community where educators at different points in the self-paced course can converse with one another or with instructors from the videos and learn from a growing community of practice. By the end of each course, educators are armed with the skills to introduce robotics or computer science in their classroom or educational setting. The design of the course was guided by a variation of the Understanding by Design (UbD) framework and included hands-on activities and challenges to keep educators engaged and excited about robotics. Some of the concepts covered include, but are not limited to, following build instructions, building a robot, updating firmware, coding the robot to drive and turn autonomously, coding a robot using multiple methods, and considerations for teaching robotics and computer science in the classroom, and more. A secondary goal of this research is to discuss how this professional development approach can serve as an example in the larger educational community and explore ways that it could be further researched or used in the future.Keywords: computer science education, online professional development, professional development, robotics education, video-based instruction
Procedia PDF Downloads 92768 Definition, Barriers to and Facilitators of Moral Distress as Perceived by Neonatal Intensive Care Physicians
Authors: M. Deligianni, P. Voultsos, E. Tsamadou
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Background/Introduction: Moral distress is a common occurrence for health professionals working in neonatal critical care. Despite a growing number of critically ill neonatal and pediatric patients, only a few articles related to moral distress as experienced by neonatal physicians have been published over the last years. Objectives/Aims: The aim of this study was to define and identify barriers to and facilitators of moral distress based on the perceptions and experiences of neonatal physicians working in neonatal intensive care units (NICUs). This pilot study is a part of a larger nationwide project. Methods: A multicenter qualitative descriptive study using focus group methodology was conducted. In-depth interviews lasting 45 to 60 minutes were audio-recorded. Once data were transcribed, conventional content analysis was used to develop the definition and categories, as well as to identify the barriers to and facilitators of moral distress. Results: Participants defined moral distress broadly in the context of neonatal critical care. A wide variation of definitions was displayed. The physicians' responses to moral distress included different feelings and other situations. The overarching categories that emerged from the data were patient-related, family-related, and physician-related factors. Moreover, organizational factors may constitute major facilitators of moral distress among neonatal physicians in NICUs. Note, however, that moral distress may be regarded as an essential component to caring for neonates in critical care. The present study provides further insight into the moral distress experienced by physicians working in Greek NICUs. Discussion/Conclusions: Understanding how neonatal and pediatric critical care nurses define moral distress and what contributes to its development is foundational to developing targeted strategies for mitigating the prevalence of moral distress among neonate physicians in the context of NICUs.Keywords: critical care, moral distress, neonatal physician, neonatal intensive care unit, NICU
Procedia PDF Downloads 145767 Kinematical Analysis of Tai Chi Chuan Players during Gait and Balance Test and Implication in Rehabilitation Exercise
Authors: Bijad Alqahtani, Graham Arnold, Weijie Wang
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Background—Tai Chi Chuan (TCC) is a type of traditional Chinese martial art and is considered a benefiting physical fitness. Advanced techniques of motion analysis have been routinely used in the clinical assessment. However, so far, little research has been done on the biomechanical assessment of TCC players in terms of gait and balance using motion analysis. Objectives—The aim of this study was to investigate whether TCC improves the lower limb conditions and balance ability using the state of the art motion analysis technologies, i.e. motion capture system, electromyography and force platform. Methods—Twenty TCC (9 male, 11 female) with age between (42-77) years old and weight (56.2-119 Kg), and eighteen Non-TCC participants (7 male, 11 female), weight (50-110 Kg) with age (43- 78) years old at the matched age as a control group were recruited in this study. Their gait and balance were collected using Vicon Nexus® to obtain the gait parameters, and kinematic parameters of hip, knee, and ankle joints in three planes of both limbs. Participants stood on force platforms to perform a single leg balance test. Then, they were asked to walk along a 10 m walkway at their comfortable speed. Participants performed 5 trials of single-leg balance for the dominant side. Also, the participants performed 3 trials of four square step balance and 10 trials of walking. From the recorded trials, three good ones were analyzed using the Vicon Plug-in-Gait model to obtain gait parameters, e.g. walking speed, cadence, stride length, and joint parameters, e.g. joint angle, force, moments, etc. Result— The temporal-spatial variables of TCC subjects were compared with the Non-TCC subjects, it was found that there was a significant difference (p < 0.05) between the groups. Moreover, it was observed that participants of TCC have significant differences in ankle, hip, and knee joints’ kinematics in the sagittal, coronal, and transverse planes such as ankle angle (19.90±19.54 deg) for TCC while (15.34±6.50 deg) for Non-TCC, and knee angle (14.96±6.40 deg) for TCC while (17.63±5.79 deg) for Non-TCC in the transverse plane. Also, the result showed that there was a significant difference between groups in the single-leg balance test, e.g. maintaining single leg stance time in the TCC participants showed longer duration (20.85±10.53 s) in compared to Non-TCC people group (13.39±8.78 s). While the result showed that there was no significant difference between groups in the four square step balance. Conclusion—Our result showed that there are significant differences between Tai Chi Chuan and Non-Tai Chi Chuan participants in the various aspects of gait analysis and balance test, as a consequence of these findings some of biomechanical parameters such as joints kinematics, gait parameters and single leg stance balance test, the Tai Chi Chuan could improve the lower limb conditions and could reduce a risk of fall for the elderly with ageing.Keywords: gait analysis, kinematics, single leg stance, Tai Chi Chuan
Procedia PDF Downloads 119766 Analysis of Magnetic Anomaly Data for Identification Structure in Subsurface of Geothermal Manifestation at Candi Umbul Area, Magelang, Central Java Province, Indonesia
Authors: N. A. Kharisa, I. Wulandari, R. Narendratama, M. I. Faisal, K. Kirana, R. Zipora, I. Arfiansah, I. Suyanto
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Acquisition of geophysical survey with magnetic method has been done in manifestation of geothermalat Candi Umbul, Grabag, Magelang, Central Java Province on 10-12 May 2013. This objective research is interpretation to interpret structural geology that control geothermal system in CandiUmbul area. The research has been finished with area size 1,5 km x 2 km and measurement space of 150 m. And each point of line space survey is 150 m using PPM Geometrics model G-856. Data processing was started with IGRF and diurnal variation correction to get total magnetic field anomaly. Then, advance processing was done until reduction to pole, upward continuation, and residual anomaly. That results become next interpretation in qualitative step. It is known that the biggest object position causes low anomaly located in central of area survey that comes from hot spring manifestation and demagnetization zone that indicates the existence of heat source activity. Then, modeling the anomaly map was used for quantitative interpretation step. The result of modeling is rock layers and geological structure model that can inform about the geothermal system. And further information from quantitative interpretations can be interpreted about lithology susceptibility. And lithology susceptibilities are andesiteas heat source has susceptibility value of (k= 0.00014 emu), basaltic as alteration rock (k= 0.0016 emu), volcanic breccia as reservoir rock (k= 0.0026 emu), andesite porfirtic as cap rock (k= 0.004 emu), lava andesite (k= 0.003 emu), and alluvium (k= 0.0007 emu). The hot spring manifestation is controlled by the normal fault which becomes a weak zone, easily passed by hot water which comes from the geothermal reservoir.Keywords: geological structure, geothermal system, magnetic, susceptibility
Procedia PDF Downloads 381765 Behaviour of RC Columns at Elevated Temperatures by NDT Techniques
Authors: D. Jagath Kumari, K. Srinivasa Rao
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Reinforced concrete column is an important structural element in a building. Concrete usually performs well in building fires. However, when it is subjected to prolonged fire exposure or unusually high temperatures, and then it will suffer significant distress. Because concrete pre-fire compressive strength generally exceeds design requirements, therefore an average strength reduction can be tolerated. However high temperature reduces the compressive strength of concrete so much that the concrete retains no useful structural strength. Therefore the residual strength and its performance of structure can be assed by NDT testing. In this paper, rebound hammer test and the ultrasonic pulse velocity (UPV) are used to evaluate the residual compressive strength and material integrity of post-fire-curing concrete subjected to elevated temperatures. Also considering the large availability of fly ash in most of the countries, an attempt was made to study the effect of high volume fly ash concrete exposed to elevated temperatures. 32 RC column specimens were made with a M20 grade concrete mix. Out of 32 column specimens 16 column specimens were made with OPC concrete and other 16 column specimens were made with HVFA concrete. All specimens having similar cross-section details. Columns were exposed to fire for temperatures from 100oC to 800o C with increments of 100o C for duration of 3 hours. Then the specimens allowed cooling to room temperature by two methods natural air cooling method and immediate water quenching method. All the specimens were tested identically, for the compressive strengths and material integrity by rebound hammer and ultrasonic pulse velocity meter respectively for study. These two tests were carried out on preheating and post heating of the column specimens. The percentage variation of compressive strengths of RCC columns with the increase in temperature has been studied and compared the results for both OPC and HVFA concretes. Physical observations of the heated columns were observed.Keywords: HVFA concrete, NDT testing, residual strength
Procedia PDF Downloads 383764 Studies on Distribution of the Doped Pr3+ Ions in the LaF3 Based Transparent Oxyfluoride Glass-Ceramic
Authors: Biswajit Pal, Amit Mallik, Anil K. Barik
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Current years have witnessed a phenomenal growth in the research on the rare earth-doped transparent host materials, the essential components in optoelectronics that meet up the increasing demand for fabrication of high quality optical devices especially in telecommunication system. The combination of low phonon energy (because of fluoride environment) and high chemical durability with superior mechanical stability (due to oxide environment) makes the oxyfluoride glass–ceramics the promising and useful materials in optoelectronics. The present work reports on the undoped and doped (1 mol% Pr2O3) glass ceramics of composition 16.52 Al2O3•1.5AlF3• 12.65LaF3•4.33Na2O•64.85 SiO2 (mol%), prepared by melting technique initially that follows annealation at 450 ºC for 1 h. The glass samples so obtained were heat treated at constant 600 ºC with a variation in heat treatment schedule (10- 80 h). TEM techniques were employed to structurally characterize the glass samples. Pr2O3 affects the phase separation in the glass and delays the onset of crystallization in the glass ceramic. The modified crystallization mechanism is established from the analysis of advanced STEM/EDXS results. The phase separated droplets after annealing turn into 10-20 nm of LaF3 nano crystals those upon scrutiny are found to be dotted with the doped Pr3+ ions within the crystals themselves. The EDXS results also suggest that the inner LaF3 crystal core is swallowed by an Al enriched layer that follows a Si enriched surrounding shell as the outer core. This greatly increases the viscosity in the periphery of the crystals that restricts further crystal growth to account for the formation of nano sized crystals.Keywords: advanced STEM/EDXS, crystallization mechanism, nano crystals, pr3+ ion doped glass and glass ceramic, structural characterization
Procedia PDF Downloads 183763 Four-Way Coupled CFD-Dem Simulation of Concrete Pipe Flow Using a Non-Newtonian Rheological Model: Investigating the Simulation of Lubrication Layer Formation and Plug Flow Zones
Authors: Tooran Tavangar, Masoud Hosseinpoor, Jeffrey S. Marshall, Ammar Yahia, Kamal Henri Khayat
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In this study, a four-way coupled CFD-DEM methodology was used to simulate the behavior of concrete pipe flow. Fresh concrete, characterized as a biphasic suspension, features aggregates comprising the solid-suspended phase with diverse particle-size distributions (PSD) within a non-Newtonian cement paste/mortar matrix forming the liquid phase. The fluid phase was simulated using CFD, while the aggregates were modeled using DEM. Interaction forces between the fluid and solid particles were considered through CFD-DEM computations. To capture the viscoelastic characteristics of the suspending fluid, a bi-viscous approach was adopted, incorporating a critical shear rate proportional to the yield stress of the mortar. In total, three diphasic suspensions were simulated, each featuring distinct particle size distributions and a concentration of 10% for five subclasses of spherical particles ranging from 1 to 17 mm in a suspending fluid. The adopted bi-viscous approach successfully simulated both un-sheared (plug flow) and sheared zones. Furthermore, shear-induced particle migration (SIPM) was assessed by examining coefficients of variation in particle concentration across the pipe. These SIPM values were then compared with results obtained using CFD-DEM under the Newtonian assumption. The study highlighted the crucial role of yield stress in the mortar phase, revealing that lower yield stress values can lead to increased flow rates and higher SIPM across the pipe.Keywords: computational fluid dynamics, concrete pumping, coupled CFD-DEM, discrete element method, plug flow, shear-induced particle migration.
Procedia PDF Downloads 58762 Fatty Acid Structure and Composition Effects of Biodiesel on Its Oxidative Stability
Authors: Gelu Varghese, Khizer Saeed
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Biodiesel is as a mixture of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats. Recent studies in the literature suggest that end property of biodiesel such as its oxidative stability (OS) is highly influenced by the structure and composition of its alkyl esters than by environmental conditions. The structure and composition of these long chain fatty acid components have been also associated with trends in Cetane number, heat of combustion, cold flow properties viscosity, and lubricity. In the present work, detailed investigation has been carried out to decouple and correlate the fatty acid structure indices of biodiesel such as degree of unsaturation, chain length, double bond orientation, and composition with its oxidative stability. Measurements were taken using the EN14214 established Rancimat oxidative stability test method (EN141120). Firstly, effects of the degree of unsaturation, chain length and bond orientation were tested for the pure fatty acids to establish their oxidative stability. Results for pure Fatty acid show that Saturated FAs are more stable than unsaturated ones to oxidation; superior oxidative stability can be achieved by blending biodiesel fuels with relatively high in saturated fatty acid contents. A lower oxidative stability is noticed when a greater quantity of double bonds is present in the methyl ester. A strong inverse relationship with the number of double bonds and the Rancimat IP values can be identified. Trans isomer Methyl elaidate shows superior stability to oxidation than its cis isomer methyl oleate (7.2 vs. 2.3). Secondly, the effects of the variation in the composition of the biodiesel were investigated and established. Finally, biodiesels with varying structure and composition were investigated and correlated.Keywords: biodiesel, fame, oxidative stability, fatty acid structure, acid composition
Procedia PDF Downloads 276761 Evaluation of IMERG Performance at Estimating the Rainfall Properties through Convective and Stratiform Rain Events in a Semi-Arid Region of Mexico
Authors: Eric Muñoz de la Torre, Julián González Trinidad, Efrén González Ramírez
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Rain varies greatly in its duration, intensity, and spatial coverage, it is important to have sub-daily rainfall data for various applications, including risk prevention. However, the ground measurements are limited by the low and irregular density of rain gauges. An alternative to this problem are the Satellite Precipitation Products (SPPs) that use passive microwave and infrared sensors to estimate rainfall, as IMERG, however, these SPPs have to be validated before their application. The aim of this study is to evaluate the performance of the IMERG: Integrated Multi-satellitE Retrievals for Global Precipitation Measurament final run V06B SPP in a semi-arid region of Mexico, using 4 automatic rain gauges (pluviographs) sub-daily data of October 2019 and June to September 2021, using the Minimum inter-event Time (MIT) criterion to separate unique rain events with a dry period of 10 hrs. for the purpose of evaluating the rainfall properties (depth, duration and intensity). Point to pixel analysis, continuous, categorical, and volumetric statistical metrics were used. Results show that IMERG is capable to estimate the rainfall depth with a slight overestimation but is unable to identify the real duration and intensity of the rain events, showing large overestimations and underestimations, respectively. The study zone presented 80 to 85 % of convective rain events, the rest were stratiform rain events, classified by the depth magnitude variation of IMERG pixels and pluviographs. IMERG showed poorer performance at detecting the first ones but had a good performance at estimating stratiform rain events that are originated by Cold Fronts.Keywords: IMERG, rainfall, rain gauge, remote sensing, statistical evaluation
Procedia PDF Downloads 62760 Seasonal Variability of M₂ Internal Tides Energetics in the Western Bay of Bengal
Authors: A. D. Rao, Sachiko Mohanty
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The Internal Waves (IWs) are generated by the flow of barotropic tide over the rapidly varying and steep topographic features like continental shelf slope, subsurface ridges, and the seamounts, etc. The IWs of the tidal frequency are generally known as internal tides. These waves have a significant influence on the vertical density and hence causes mixing in the region. Such waves are also important in submarine acoustics, underwater navigation, offshore structures, ocean mixing and biogeochemical processes, etc. over the shelf-slope region. The seasonal variability of internal tides in the Bay of Bengal with special emphasis on its energetics is examined by using three-dimensional MITgcm model. The numerical simulations are performed for different periods covering August-September, 2013; November-December, 2013 and March-April, 2014 representing monsoon, post-monsoon and pre-monsoon seasons respectively during which high temporal resolution in-situ data sets are available. The model is initially validated through the spectral estimates of density and the baroclinic velocities. From the estimates, it is inferred that the internal tides associated with semi-diurnal frequency are more dominant in both observations and model simulations for November-December and March-April. However, in August, the estimate is found to be maximum near-inertial frequency at all the available depths. The observed vertical structure of the baroclinic velocities and its magnitude are found to be well captured by the model. EOF analysis is performed to decompose the zonal and meridional baroclinic tidal currents into different vertical modes. The analysis suggests that about 70-80% of the total variance comes from Mode-1 semi-diurnal internal tide in both observations as well as in the model simulations. The first three modes are sufficient to describe most of the variability for semidiurnal internal tides, as they represent 90-95% of the total variance for all the seasons. The phase speed, group speed, and wavelength are found to be maximum for post-monsoon season compared to other two seasons. The model simulation suggests that the internal tide is generated all along the shelf-slope regions and propagate away from the generation sites in all the months. The model simulated energy dissipation rate infers that its maximum occurs at the generation sites and hence the local mixing due to internal tide is maximum at these sites. The spatial distribution of available potential energy is found to be maximum in November (20kg/m²) in northern BoB and minimum in August (14kg/m²). The detailed energy budget calculation are made for all the seasons and results are analysed.Keywords: available potential energy, baroclinic energy flux, internal tides, Bay of Bengal
Procedia PDF Downloads 164759 The Effect of Traffic Load on the Maximum Response of a Cable-Stayed Bridge under Blast Loads
Authors: S. K. Hashemi, M. A. Bradford, H. R. Valipour
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The Recent collapse of bridges has raised the awareness about safety and robustness of bridges subjected to extreme loading scenarios such as intentional/unintentional blast loads. The air blast generated by the explosion of bombs or fuel tankers leads to high-magnitude short-duration loading scenarios that can cause severe structural damage and loss of critical structural members. Hence, more attentions need to put towards bridge structures to develop guidelines to increase the resistance of such structures against the probable blast. Recent advancements in numerical methods have brought about the viable and cost effective facilities to simulate complicated blast scenarios and subsequently provide useful reference for safeguarding design of critical infrastructures. In the previous studies common bridge responses to blast load, the traffic load is sometimes not included in the analysis. Including traffic load will increase the axial compression in bridge piers especially when the axial load is relatively small. Traffic load also can reduce the uplift of girders and deck when the bridge experiences under deck explosion. For more complicated structures like cable-stayed or suspension bridges, however, the effect of traffic loads can be completely different. The tension in the cables increase and progressive collapse is likely to happen while traffic loads exist. Accordingly, this study is an attempt to simulate the effect of traffic load cases on the maximum local and global response of an entire cable-stayed bridge subjected to blast loadings using LS-DYNA explicit finite element code. The blast loads ranged from small to large explosion placed at different positions above the deck. Furthermore, the variation of the traffic load factor in the load combination and its effect on the dynamic response of the bridge under blast load is investigated.Keywords: blast, cable-stayed bridge, LS-DYNA, numerical, traffic load
Procedia PDF Downloads 327758 The Issues of Irrigation and Drainage in Kebbi State and Their Effective Solution for a Sustainable Agriculture in Kebbi State, Nigeria
Authors: Mumtaz Ahmed Sohag, Ishaq Ahmed Sohag
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Kebbi State, located in the Nort-West of Nigeria, is rich in water resources as the major rivers viz. Niger and Rima irrigate a vast majority of land. Besides, there is significant amount of groundwater, which farmers use for agriculture purpose. The groundwater is also a major source of agricultural and domestic water as wells are installed in almost all parts of the region. Although Kebbi State is rich in water, however, there are some pertinent issues which are hampering its agricultural productivity. The low lands (locally called Fadama), has spread out to a vast area. It is inundated every year during the rainy season which lasts from June to September every year. The farmers grow rice during the rainy season when water is standing. They cannot do further agricultural activity for almost two months due to high standing water. This has resulted in widespread waterlogging problem. Besides, the impact of climate change is resulting in rapid variation in river/stream flows. The information about water bodies regarding the availability of water for agricultural and other uses and the behavior of rivers at different flows is seldom available. Furthermore, sediment load (suspended and bedload) is not measured due to which land erosion cannot be countered effectively. This study, carried out in seven different irrigation regions of Kebbi state, found that diversion structures need to be constructed at some strategic locations for the supply of surface water to the farmers. The water table needs to be lowered through an effective drainage system. The monitoring of water bodies is crucial for sound data to help efficient regulation and management of water. Construction of embankments is necessary to control frequent floods in the rivers of Niger and Rima. Furthermore, farmers need capacity and awareness for participatory irrigation management.Keywords: water bodies, floods, agriculture, waterlogging
Procedia PDF Downloads 232757 Geochemical Baseline and Origin of Trace Elements in Soils and Sediments around Selibe-Phikwe Cu-Ni Mining Town, Botswana
Authors: Fiona S. Motswaiso, Kengo Nakamura, Takeshi Komai
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Heavy metals may occur naturally in rocks and soils, but elevated quantities of them are being gradually released into the environment by anthropogenic activities such as mining. In order to address issues of heavy metal water and soil pollution, a distinction needs to be made between natural and anthropogenic anomalies. The current study aims at characterizing the spatial distribution of trace elements and evaluate site-specific geochemical background concentrations of trace elements in the mine soils examined, and also to discriminate between lithogenic and anthropogenic sources of enrichment around a copper-nickel mining town in Selibe-Phikwe, Botswana. A total of 20 Soil samples, 11 river sediment, and 9 river water samples were collected from an area of 625m² within the precincts of the mine and the smelter. The concentrations of metals (Cu, Ni, Pb, Zn, Cr, Ni, Mn, As, Pb, and Co) were determined by using an ICP-MS after digestion with aqua regia. Major elements were also determined using ED-XRF. Water pH and EC were measured on site and recorded while soil pH and EC were also determined in the laboratory after performing water elution tests. The highest Cu and Ni concentrations in soil are 593mg/kg and 453mg/kg respectively, which is 3 times higher than the crustal composition values and 2 times higher than the South African minimum allowable levels of heavy metals in soils. The level of copper contamination was higher than that of nickel and other contaminants. Water pH levels ranged from basic (9) to very acidic (3) in areas closer to the mine/smelter. There is high variation in heavy metal concentration, eg. Cu suggesting that some sites depict regional natural background concentrations while other depict anthropogenic sources.Keywords: contamination, geochemical baseline, heavy metals, soils
Procedia PDF Downloads 149756 Basin Geometry and Salt Structures in the Knana/Ragoubet Mahjbia Ranges, North of Tunisia
Authors: Mohamed Montassar Ben Slama, Mohamed Fadel Ladeb, Mohamed Ghanmi, Mohamed Ben Youssef, Fouad Zargouni
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The salt province Basin in Northern Tunisia is a complex of late Triassic to Early Cretaceous rift and sag basins which was inverted during the Tertiary folding. The deposition of evaporitic sediments during the Late Triassic times played a major role in the subsequent tectonic evolution of the basin. Within southern tethyan passive marge, the ductile salt mass shown early mobilization, vertical transport and withdrawal of the evaporites. These movements influenced the sedimentation during the late Jurassic and Early Cretaceous. The evaporites also influenced deformation during the inversion of the basin and the development of the Tertiary and Quaternary folding. In the studied area, the biostratigraphic and tectonic map analysis of the region of Jebel el Asoued / Ragoubet el Mahjbia can resolve between the hypotheses of the diapiric intrusion of the Triassic salt and the lateral spreading of the Triassic salt as salt ‘glacier’. Also the variation in thickness and facies of the Aptian sediments demonstrates the existence of continental rise architecture at the Aptian time. The observation in a mappable outcrop of the extension segment of the graben fault of Bou Arada on the one hand confirms the existence of a Cretaceous extensive architecture and the tectonic inversion during the Tertiary time has not filled the main game distension. The extent of our observations of Triassic/Aptian and Triassic/Early Campanian contacts, we propose a composite salt ‘glacier’ model as the structures recorded in the Gulf of Mexico in the subsurface and in the Ouenza east Algeria and in Tunisia within Fedj el Adoum, Touiref-Nebeur and Jebel Ech Cheid in the outcrops.Keywords: Cretaceous rift, salt ‘glassier’, tertiary folding, Tunisia
Procedia PDF Downloads 371755 Climate Variability and Its Impacts on Rice (Oryza sativa) Productivity in Dass Local Government Area of Bauchi State, Nigeria
Authors: Auwal Garba, Rabiu Maijama’a, Abdullahi Muhammad Jalam
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Variability in climate has affected the agricultural production all over the globe. This concern has motivated important changes in the field of research during the last decade. Climate variability is believed to have declining effects towards rice production in Nigeria. This study examined climate variability and its impact on rice productivity in Dass Local Government Area, Bauchi State, by employing Linear Trend Model (LTM), analysis of variance (ANOVA) and regression analysis. Annual seasonal data of the climatic variables for temperature (min. and max), rainfall, and solar radiation from 1990 to 2015 were used. Results confirmed that 74.4% of the total variation in rice yield in the study area was explained by the changes in the independent variables. That is to say, temperature (minimum and maximum), rainfall, and solar radiation explained rice yield with 74.4% in the study area. Rising mean maximum temperature would lead to reduction in rice production while moderate increase in mean minimum temperature would be advantageous towards rice production, and the persistent rise in the mean maximum temperature, in the long run, will have more negatively affect rice production in the future. It is, therefore, important to promote agro-meteorological advisory services, which will be useful in farm planning and yield sustainability. Closer collaboration among the meteorologist and agricultural scientist is needed to increase the awareness about the existing database, crop weather models among others, with a view to reaping the full benefits of research on specific problems and sustainable yield management and also there should be a special initiative by the ADPs (State Agricultural Development Programme) towards promoting best agricultural practices that are resilient to climate variability in rice production and yield sustainability.Keywords: climate variability, impact, productivity, rice
Procedia PDF Downloads 96754 The Impact of Model Specification Decisions on the Teacher ValuE-added Effectiveness: Choosing the Correct Predictors
Authors: Ismail Aslantas
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Value-Added Models (VAMs), the statistical methods for evaluating the effectiveness of teachers and schools based on student achievement growth, has attracted decision-makers’ and researchers’ attention over the last decades. As a result of this attention, many studies have conducted in recent years to discuss these statistical models from different aspects. This research focused on the importance of conceptual variables in VAM estimations; therefor, this research was undertaken to examine the extent to which value-added effectiveness estimates for teachers can be affected by using context predictions. Using longitudinal data over three years from the international school context, value-added teacher effectiveness was estimated by ordinary least-square value-added models, and the effectiveness of the teachers was examined. The longitudinal dataset in this study consisted of three major sources: students’ attainment scores up to three years and their characteristics, teacher background information, and school characteristics. A total of 1,027 teachers and their 35,355 students who were in eighth grade were examined for understanding the impact of model specifications on the value-added teacher effectiveness evaluation. Models were created using selection methods that adding a predictor on each step, then removing it and adding another one on a subsequent step and evaluating changes in model fit was checked by reviewing changes in R² values. Cohen’s effect size statistics were also employed in order to find out the degree of the relationship between teacher characteristics and their effectiveness. Overall, the results indicated that prior attainment score is the most powerful predictor of the current attainment score. 47.1 percent of the variation in grade 8 math score can be explained by the prior attainment score in grade 7. The research findings raise issues to be considered in VAM implementations for teacher evaluations and make suggestions to researchers and practitioners.Keywords: model specification, teacher effectiveness, teacher performance evaluation, value-added model
Procedia PDF Downloads 124753 Motor Speech Profile of Marathi Speaking Adults and Children
Authors: Anindita Banik, Anjali Kant, Aninda Duti Banik, Arun Banik
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Speech is a complex, dynamic unique motor activity through which we express thoughts and emotions and respond to and control our environment. The aim was based to compare select Motor Speech parameters and their sub parameters across typical Marathi speaking adults and children. The subjects included a total of 300 divided into Group I, II, III including males and females. Subjects included were reported of no significant medical history and had a rating of 0-1 on GRBAS scale. The recordings were obtained utilizing three stimuli for the acoustic analysis of Diadochokinetic rate (DDK), Second Formant Transition, Voice and Tremor and its sub parameters. And these aforementioned parameters were acoustically analyzed in Motor Speech Profile software in VisiPitch IV. The statistical analyses were done by applying descriptive statistics and Two- Way ANOVA.The results obtained showed statistically significant difference across age groups and gender for the aforementioned parameters and its sub parameters.In DDK, for avp (ms) there was a significant difference only across age groups. However, for avr (/s) there was a significant difference across age groups and gender. It was observed that there was an increase in rate with an increase in age groups. The second formant transition sub parameter F2 magn (Hz) also showed a statistically significant difference across both age groups and gender. There was an increase in mean value with an increase in age. Females had a higher mean when compared to males. For F2 rate (/s) a statistically significant difference was observed across age groups. There was an increase in mean value with increase in age. It was observed for Voice and Tremor MFTR (%) that a statistically significant difference was present across age groups and gender. Also for RATR (Hz) there was statistically significant difference across both age groups and gender. In other words, the values of MFTR and RATR increased with an increase in age. Thus, this study highlights the variation of the motor speech parameters amongst the typical population which would be beneficial for comparison with the individuals with motor speech disorders for assessment and management.Keywords: adult, children, diadochokinetic rate, second formant transition, tremor, voice
Procedia PDF Downloads 302752 Design and Implementation of 3kVA Grid-Tied Transformerless Power Inverter for Solar Photovoltaic Application
Authors: Daniel O. Johnson, Abiodun A. Ogunseye, Aaron Aransiola, Majors Samuel
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Power Inverter is a very important device in renewable energy use particularly for solar photovoltaic power application because it is the effective interface between the DC power generator and the load or the grid. Transformerless inverter is getting more and more preferred to the power converter with galvanic isolation transformer and may eventually supplant it. Transformerless inverter offers advantages of improved DC to AC conversion and power delivery efficiency; and reduced system cost, weight and complexity. This work presents thorough analysis of the design and prototyping of 3KVA grid-tie transformerless inverter. The inverter employs electronic switching method with minimised heat generation in the system and operates based on the principle of pulse-width modulation (PWM). The design is such that it can take two inputs, one from PV arrays and the other from Battery Energy Storage BES and addresses the safety challenge of leakage current. The inverter system was designed around microcontroller system, modeled with Proteus® software for simulation and testing of the viability of the designed inverter circuit. The firmware governing the operation of the grid-tied inverter is written in C language and was developed using MicroC software by Mikroelectronica® for writing sine wave signal code for synchronization to the grid. The simulation results show that the designed inverter circuit performs excellently with very high efficiency, good quality sinusoidal output waveform, negligible harmonics and gives very stable performance under voltage variation from 36VDC to 60VDC input. The prototype confirmed the simulated results and was successfully synchronized with the utility supply. The comprehensive analyses of the circuit design, the prototype and explanation on overall performance will be presented.Keywords: grid-tied inverter, leakage current, photovoltaic system, power electronic, transformerless inverter
Procedia PDF Downloads 284751 Plant Water Relations and Forage Quality in Leucaena leucocephala (Lam.) de Wit and Acacia saligna (Labill.) as Affected by Salinity Stress
Authors: Maher J. Tadros
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This research was conducted to study the effect of different salinity concentrations on the plant water relation and forage quality on two multipurpose forest trees species seedlings Leucaena leucocephala (Lam.) de wit and Acacia saligna (Labill.). Five different salinity concentrations mixture between sodium chloride and calcium chloride (v/v, 1:1) were applied. The control (Distilled Water), 2000, 4000, 6000, and 8000 ppm were used to water the seedlings for 3 months. The research results presented showed a marked variation among the two species in response to salinity. The Leucaena was able to withstand the highest level of salinity compared to Acacia all over the studied parameters except in the relative water content. Although all the morphological characteristics studied for the two species showed a marked decrease under the different salinity concentrations, except the shoot/root ratio that showed a trend of increase. The water stress measure the leaf water potential was more negative with as the relative water content increase under that saline conditions compared to the control. The forage quality represented by the crude protein and nitrogen content were low at 6000 ppm compared to the 8000 ppm in L. Leucocephala that increased compared that level in A. saligna. Also the results showed that growing both Leucaena and Acacia provide a good source of forage when that grow under saline condition which will be of great benefits to the agricultural sector especially in the arid and semiarid areas were these species can provide forage with high quality forage all year around when grown under irrigation with saline. This research recommended such species to be utilized and grown for forages under saline conditions.Keywords: plant water relations, growth performance, salinity stress, protein content, forage quality, multipurpose trees
Procedia PDF Downloads 386750 Factors Associated with Oral Cavity Colonization by Candida albicans
Authors: Nwafia Ifeyinwa Nkeiruka, Nwafia Walter Chukwuma
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Since the early 1980’s fungi have emerged as major causes of human diseases, especially among immunocompromised. The most commonly isolated yeast is Candida albicans and constitutes the 4th most common nosocomial BSI in humans. It is progressive and cumulative and become more complex over time.It can even lead to leaky gut syndrome that causes food and environmental allergies. It is worthy of note that all the available data on oral Candida risk factors in humans were documented essentially using data from studies conducted in other areas, hence there is need for comparative and complementary information from the South eastern part of Nigeria. Method: 200 subjects of all age groups of both sexes were randomly examined,by swabbing their palatine mucosa and dorsal tongue with sterile cotton wool,then cultured into Sabouraud dextrose agar plates supplemented with antibiotics and incubated aerobically at 37 degree for 48 hrs. Identification of Candida albicans was done by germ tubes tests, chlamydospores production on cornmeal agar supplemented with 1% Tween 80.Sugar and nitrogen assimilation test using API 20C Auxanogram and potassium nitrate agar. Results: Out of 30 samples that were positive for candida, 15 (50%) were candida albicans. Using the anova test (P < 0.05) this variation is significant (P = 0016). followed by C. dublinensis 3 (13%), C. tropicalis 3 (10%), C. pseudotropicalis 3 (10%), C, glabrata 2 (7%), C. parapsilosis 2 (7%) and lastly C. krusei 1 (3%).However, 53% of the patients were female while 47% were male. Among the HIV positive isolates.67% were HIV isolates not on drugs while 33% positives isolates were on drugs and the percentages of candida species in these patients were as follows C. albicans were 45% followed by C. glabrata and C.tropicalis which were 17% each, C.parapsilosis, C.dubliensis and C.pseudotropicalis were all 8% each. Conclusion: Oral Candidiasis is a marker of systemic diseases and in some cases, it may be the first clinical presentation. There is need for more intensive clinical and laboratory monitoring and possible early intervention to prevent the reoccurrence and resistance to treatment.Keywords: oral cavity, Candida species, oral Candidiasis, risk factors
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