Search results for: two-parameter exponential distribution

Authors: Sohini Manna, Jong Woo Kim, Oleg Shpyrko, Eric E. Fullerton

Abstract:

CVD techniques have emerged as a promising approach in the formation of a broad range of nanostructured materials. The realization of many practical applications will require efficient and economical synthesis techniques that preferably avoid the need for templates or costly single-crystal substrates and also afford process adaptability. Towards this end, we have developed a single-step route for the reduction-type synthesis of nanostructured Ni materials using a thermal CVD method. By tuning the CVD growth parameters, we can synthesize morphologically dissimilar nanostructures including single-crystal cubes and Au nanostructures which form atop untreated amorphous SiO2||Si substrates. An understanding of the new properties that emerge in these nanostructures materials and their relationship to function will lead to for a broad range of magnetostrictive devices as well as other catalysis, fuel cell, sensor, and battery applications based on high-surface-area transition-metal nanostructures. We use coherent X-ray diffraction imaging technique to obtain 3-D image and strain maps of individual nanocrystals. Coherent x-ray diffractive imaging (CXDI) is a technique that provides the overall shape of a nanostructure and the lattice distortion based on the combination of highly brilliant coherent x-ray sources and phase retrieval algorithm. We observe a fine interplay of reduction of surface energy vs internal stress, which plays an important role in the morphology of nano-crystals. The strain distribution is influenced by the metal-substrate interface and metal-air interface, which arise due to differences in their thermal expansion. We find the lattice strain at the surface of the octahedral gold nanocrystal agrees well with the predictions of the Young-Laplace equation quantitatively, but exhibits a discrepancy near the nanocrystal-substrate interface resulting from the interface. The strain in the bottom side of the Ni nanocube, which is contacted on the substrate surface is compressive. This is caused by dissimilar thermal expansion coefficients between Ni nanocube and Si substrate. Research at UCSD support by NSF DMR Award # 1411335.

Keywords: CVD, nanostructures, strain, CXRD

Procedia PDF Downloads 392

Authors: Hanen Khanchel, Karim Ben Kahla

Abstract:

Pharmaceutical companies are facing competition. Indeed, the price differences between competing products can be such that it becomes difficult to compensate them by differences in value added. The conditions of competition are no longer homogeneous for the players involved. The price of a product is a given that puts a company and its customer face to face. However, price fixing obliges the company to consider internal factors relating to production costs and external factors such as customer attitudes, the existence of regulations and the structure of the market on which the firm evolved. In setting the selling price, the company must first take into account internal factors relating to its costs: costs of production fall into two categories, fixed costs and variable costs that depend on the quantities produced. The company cannot consider selling below what it costs the product. It, therefore, calculates the unit cost of production to which it adds the unit cost of distribution, enabling it to know the unit cost of production of the product. The company adds its margin and thus determines its selling price. The margin is used to remunerate the capital providers and to finance the activity of the company and its investments. Production costs are related to the quantities produced: large-scale production generally reduces the unit cost of production, which is an asset for companies with mass production markets. This shows that small and medium-sized companies with limited market segments need to make greater efforts to ensure their profit margins. As a result, and faced with high and low market prices for raw materials and increasing staff costs, the company must seek to optimize its production time in order to reduce loads and eliminate waste. Then, the customer pays only value added. Thus, and based on this principle we decided to create a project that deals with the problem of waste in our company, and having as objectives the reduction of production costs and improvement of performance indicators. This paper presents the implementation of the Value Stream Mapping (VSM) project in a pharmaceutical company. It is structured as follows: 1) determination of the family of products, 2) drawing of the current state, 3) drawing of the future state, 4) action plan and implementation.

Keywords: VSM, waste, production time, kaizen, cartography, improvement

Procedia PDF Downloads 150

Authors: Vhahangwele Belemu, Isaac Busayo Oluwatayo

Abstract:

Post-harvest losses pose a serious challenge to smallholder fruit crop farmers, especially in the rural communities of South Africa, affecting their economic livelihoods and food security. This study investigated the post-harvest handling practices and technologies harnessed by smallholder fruit crop farmers in the Vhembe district of Limpopo province, South Africa. Data were collected on a random sample of 224 smallholder fruit crop farmers selected from the four municipalities of the district using a multistage sampling technique. Analytical tools employed include descriptive statistics and the tobit regression model. A descriptive analysis of farmers’ socioeconomic characteristics showed that a sizeable number of these farmers are still in their active working age (mean = 52 years) with more males (63.8%) than their female (36.2%) counterparts. Respondents’ distribution by educational status revealed that only a few of these had no formal education (2.2%), with the majority having secondary education (48.7%). Results of data analysis further revealed that the prominent post-harvest technologies and handling practices harnessed by these farmers include using appropriate harvesting techniques (20.5%), selling at a reduced price (19.6%), transportation consideration (18.3%), cleaning and disinfecting (17.9%), sorting and grading (16.5%), manual cleaning (15.6%) and packaging technique (11.6%) among others. The result of the Tobit regression analysis conducted to examine the determinants of post-harvest technologies and handling practices harnessed showed that age, educational status of respondents, awareness of technology/handling practices, farm size, access to credit, extension contact, and membership of association were the significant factors. The study suggests enhanced awareness creation, access to credit facility and improved access to market as important factors to consider by relevant stakeholders to assist smallholder fruit crop farmers in the study area.

Keywords: fruit crop farmers, handling practices, post harvest losses, smallholder, Vhembe District, South Africa

Procedia PDF Downloads 56

Authors: Irfan Anjum Manarvi, Zahid Ali kaimkhani

Abstract:

Predicting location of the fracture in human bones has been a keen area of research for the past few decades. A variety of tests for hardness, deformation, and strain field measurement have been conducted in the past; but considered insufficient due to various limitations. Researchers, therefore, have proposed further studies due to inaccuracies in measurement methods, testing machines, and experimental errors. Advancement and availability of hardware, measuring instrumentation, and testing machines can now provide remedies to these limitations. The human foot is a critical part of the body exposed to various forces throughout its life. A number of products are developed for using it for protection and care, which many times do not provide sufficient protection and may itself become a source of stress due to non-consideration of the delicacy of bones in the feet. A continuous strain or overloading on feet may occur resulting to discomfort and even fracture. Mechanical properties of Tarsals, Metatarsals, and phalanges are, therefore, the primary area of consideration for all such design applications. Hardness is one of the mechanical properties which are considered very important to establish the mechanical resistance behavior of a material against applied loads. Past researchers have worked in the areas of investigating mechanical properties of these bones. However, their results were based on a limited number of experiments and taking average values of hardness due to either limitation of samples or testing instruments. Therefore, they proposed further studies in this area. The present research has been carried out to develop a hardness map of the human foot by measuring micro hardness at various locations of these bones. Results are compiled in the form of distance from a reference point on a bone and the hardness values for each surface. The number of test results is far more than previous studies and are spread over a typical bone to give a complete hardness map of these bones. These results could also be used to establish other properties such as stress and strain distribution in the bones. Also, industrial engineers could use it for design and development of various accessories for human feet health care and comfort and further research in the same areas.

Keywords: tarsals, metatarsals, phalanges, hardness testing, biomechanics of human foot

Procedia PDF Downloads 421

Authors: Desmond Young

Abstract:

In building services electrical design, a key element of any project will be assessing the electrical load requirements. This needs to be done early in the design process to allow the selection of infrastructure that would be required to meet the electrical needs of the type of building. The type of building will define the type of assessment made, and the values applied in defining the maximum demand for the building, and ultimately the size of supply or infrastructure required, and the application that needs to be made to the distribution network operator, or alternatively to an independent network operator. The fact that this assessment needs to be undertaken early in the design process provides limits on the type of assessment that can be used, as different methods require different types of information, and sometimes this information is not available until the latter stages of a project. A common method applied in the earlier design stages of a project, typically during stages 1,2 & 3, is the use of benchmarks. It is a possibility that some of the benchmarks applied are excessive in relation to the current loads that exist in a modern installation. This lack of accuracy is based on information which does not correspond to the actual equipment loads that are used. This includes lighting and small power loads, where the use of more efficient equipment and lighting has reduced the maximum demand required. The electrical load can be used as part of the process to assess the heat generated from the equipment, with the heat gains from other sources, this feeds into the sizing of the infrastructure required to cool the building. Any overestimation of the loads would contribute to the increase in the design load for the heating and ventilation systems. Finally, with the new policies driving the industry to decarbonise buildings, a prime example being the recently introduced London Plan, loads are potentially going to increase. In addition, with the advent of the pandemic and changes to working practices, and the adoption of electric heating and vehicles, a better understanding of the loads that should be applied will aid in ensuring that infrastructure is not oversized, as a cost to the client, or undersized to the detriment of the building. In addition, more accurate benchmarks and methods will allow assessments to be made for the incorporation of energy storage and renewable technologies as these technologies become more common in buildings new or refurbished.

Keywords: energy, ADMD, electrical load assessment, energy benchmarks

Procedia PDF Downloads 112

Authors: Lily Ingsrisawang, Tasanee Nacharoen

Abstract:

Introduction: The problems of unbalanced data sets generally appear in real world applications. Due to unequal class distribution, many research papers found that the performance of existing classifier tends to be biased towards the majority class. The k -nearest neighbors’ nonparametric discriminant analysis is one method that was proposed for classifying unbalanced classes with good performance. Hence, the methods of discriminant analysis are of interest to us in investigating misclassification error rates for class-imbalanced data of three diabetes risk groups. Objective: The purpose of this study was to compare the classification performance between parametric discriminant analysis and nonparametric discriminant analysis in a three-class classification application of class-imbalanced data of diabetes risk groups. Methods: Data from a healthy project for 599 staffs in a government hospital in Bangkok were obtained for the classification problem. The staffs were diagnosed into one of three diabetes risk groups: non-risk (90%), risk (5%), and diabetic (5%). The original data along with the variables; diabetes risk group, age, gender, cholesterol, and BMI was analyzed and bootstrapped up to 50 and 100 samples, 599 observations per sample, for additional estimation of misclassification error rate. Each data set was explored for the departure of multivariate normality and the equality of covariance matrices of the three risk groups. Both the original data and the bootstrap samples show non-normality and unequal covariance matrices. The parametric linear discriminant function, quadratic discriminant function, and the nonparametric k-nearest neighbors’ discriminant function were performed over 50 and 100 bootstrap samples and applied to the original data. In finding the optimal classification rule, the choices of prior probabilities were set up for both equal proportions (0.33: 0.33: 0.33) and unequal proportions with three choices of (0.90:0.05:0.05), (0.80: 0.10: 0.10) or (0.70, 0.15, 0.15). Results: The results from 50 and 100 bootstrap samples indicated that the k-nearest neighbors approach when k = 3 or k = 4 and the prior probabilities of {non-risk:risk:diabetic} as {0.90:0.05:0.05} or {0.80:0.10:0.10} gave the smallest error rate of misclassification. Conclusion: The k-nearest neighbors approach would be suggested for classifying a three-class-imbalanced data of diabetes risk groups.

Keywords: error rate, bootstrap, diabetes risk groups, k-nearest neighbors

Procedia PDF Downloads 434

Authors: Deepak Kakde, Steve Howdle, Derek Irvine, Cameron Alexander

Abstract:

The poor aqueous solubility is one of the major obstacles in the formulation development of many drugs. Around 70% of drugs are poorly soluble in aqueous media. In the last few decades, micelles have emerged as one of the major tools for solubilization of hydrophobic drugs. Micelles are nanosized structures (10-100nm) obtained by self-assembly of amphiphilic molecules into the water. The hydrophobic part of the micelle forms core which is surrounded by a hydrophilic outer shell called corona. These core-shell structures have been used as a drug delivery vehicle for many years. Although, the utility of micelles have been reduced due to the lack of sustainable materials. In the present study, a novel methoxy poly(ethylene glycol)-b-poly(ε-decalactone) (mPEG-b-PεDL) copolymer was synthesized by ring opening polymerization (ROP) of renewable ε-decalactone (ε-DL) monomers on methoxy poly(ethylene glycol) (mPEG) initiator using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a organocatalyst. All the reactions were conducted in bulk to avoid the use of toxic organic solvents. The copolymer was characterized by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC).The mPEG-b-PεDL block copolymeric micelles containing indomethacin (IND) were prepared by nanoprecipitation method and evaluated as drug delivery vehicle. The size of the micelles was less than 40nm with narrow polydispersity pattern. TEM image showed uniform distribution of spherical micelles defined by clear surface boundary. The indomethacin loading was 7.4% for copolymer with molecular weight of 13000 and drug/polymer weight ratio of 4/50. The higher drug/polymer ratio decreased the drug loading. The drug release study in PBS (pH7.4) showed a sustained release of drug over a period of 24hr. In conclusion, we have developed a new sustainable polymeric material for IND delivery by combining the green synthetic approach with the use of renewable monomer for sustainable development of polymeric nanomedicine.

Keywords: dopolymer, ε-decalactone, indomethacin, micelles

Procedia PDF Downloads 295

Authors: Raja Asad Zaheer, Aisha Tanveer, Hafza Mehreen Fatima

Abstract:

Global Software Development (GSD) is becoming a common norm in software industry, despite of the fact that global distribution of the teams presents special issues for effective communication and coordination of the teams. Now trends are changing and project management for distributed teams is no longer in a limbo. GSD can be effectively established using agile and project managers can use different agile techniques/tools for solving the problems associated with distributed teams. Agile methodologies like scrum and XP have been successfully used with distributed teams. We have employed exploratory research method to analyze different recent studies related to challenges of GSD and their proposed solutions. In our study, we had deep insight in six commonly faced challenges: communication and coordination, temporal differences, cultural differences, knowledge sharing/group awareness, speed and communication tools. We have established that each of these challenges cannot be neglected for distributed teams of any kind. They are interlinked and as an aggregated whole can cause the failure of projects. In this paper we have focused on creating a scalable framework for detecting and overcoming these commonly faced challenges. In the proposed solution, our objective is to suggest agile techniques/tools relevant to a particular problem faced by the organizations related to the management of distributed teams. We focused mainly on scrum and XP techniques/tools because they are widely accepted and used in the industry. Our solution identifies the problem and suggests an appropriate technique/tool to help solve the problem based on globally shared knowledgebase. We can establish a cause and effect relationship using a fishbone diagram based on the inputs provided for issues commonly faced by organizations. Based on the identified cause, suitable tool is suggested, our framework suggests a suitable tool. Hence, a scalable, extensible, self-learning, intelligent framework proposed will help implement and assess GSD to achieve maximum out of it. Globally shared knowledgebase will help new organizations to easily adapt best practices set forth by the practicing organizations.

Keywords: agile project management, agile tools/techniques, distributed teams, global software development

Procedia PDF Downloads 313

Authors: Duncan Fraser

Abstract:

A 3-Dimensional (3D) conceptual site model was developed using the Leapfrog Works® platform utilising a comprehensive historical dataset for a large former Gasworks site in Fitzroy, Melbourne. The gasworks had been constructed across two fractured geological units with varying hydraulic conductivities. A Newer Volcanic (basaltic) outcrop covered approximately half of the site and was overlying a fractured Melbourne formation (Siltstone) bedrock outcropping over the remaining portion. During the investigative phase of works, a dense non-aqueous phase liquid (DNAPL) plume (coal tar) was identified within both geological units in the subsurface originating from multiple sources, including gasholders, tar wells, condensers, and leaking pipework. The first stage of model development was undertaken to determine the horizontal and vertical extents of the coal tar in the subsurface and assess the potential causality between potential sources, plume location, and site geology. Concentrations of key contaminants of interest (COIs) were also interpolated within Leapfrog to refine the distribution of contaminated soils. The model was subsequently used to develop a robust soil remediation strategy and achieve endorsement from an Environmental Auditor. A change in project scope, following the removal and validation of the three former gasholders, necessitated the additional excavation of a significant volume of residual contaminated rock to allow for the future construction of two-story underground basements. To assess financial liabilities associated with the offsite disposal or thermal treatment of material, the 3D model was updated with three years of additional analytical data from the active remediation phase of works. Chemical concentrations and the residual tar plume within the rock fractures were modelled to pre-classify the in-situ material and enhance separation strategies to prevent the unnecessary treatment of material and reduce costs.

Keywords: 3D model, contaminated land, Leapfrog, remediation

Procedia PDF Downloads 131

Authors: Abduladim Maitieg

Abstract:

The oil manufacture is one of the main productive activities in Libya and has a massive infrastructure, including offshore drilling and exploration and wide oil export platform sites that located in coastal area. There is a threat to marine and coastal area of oil spills is greatest in those sites with a high spills comes from urban and industry, parallel to that, monitoring oil spills and risk emergency strategy is weakness, An approach for estimating a coastal resources vulnerability to oil spills is presented based on abundance, environmental and Scio-economic importance, distance to oil spill resources and oil risk likelihood. As many as 10 coastal resources were selected for oil spill assessment at the coast. This study aims to evaluate, determine and establish vulnerable coastal resource maps and estimating the rate of oil spill comes for different oil spill resources in Misratah marine environment. In the study area there are two type of oil spill resources, major oil resources come from offshore oil industries which are 96 km from the Coast and Loading/Uploading oil platform. However, the miner oil resources come from urban sewage pipes and fish ports. In order to analyse the collected database, the Geographic information system software has been used to identify oil spill location, to map oil tracks in front of study area, and developing seasonal vulnerable costal resources maps. This work shows that there is a differential distribution of the degree of vulnerability to oil spills along the coastline, with values ranging from high vulnerability and low vulnerability, and highlights the link between oil spill movement and coastal resources vulnerability. The results of assessment found most of costal freshwater spring sites are highly vulnerable to oil spill due to their location on the intertidal zone and their close to proximity to oil spills recourses such as Zreag coast. Furthermore, the Saltmarsh coastline is highly vulnerable to oil spill risk due to characterisation as it contains a nesting area of sea turtles and feeding places for migratory birds and the . Oil will reach the coast in winter season according to oil spill movement. Coastal tourist beaches in the north coast are considered as highly vulnerable to oil spill due to location and closeness to oil spill resources.

Keywords: coastal recourses vulnerability, oil spill trajectory, gnome software, Misratah coast- Libya, GIS

Procedia PDF Downloads 314

Authors: Parimalah Velo, Ahmad Zakaria

Abstract:

Introduction: Monte Carlo simulations of preclinical imaging systems allow opportunity to enable new research that could range from designing hardware up to discovery of new imaging application. The simulation system which could accurately model an imaging modality provides a platform for imaging developments that might be inconvenient in physical experiment systems due to the expense, unnecessary radiation exposures and technological difficulties. The aim of present study is to validate the Monte Carlo simulation of thyroid phantom imaging using Geant4-GATE for Siemen’s e-cam single head gamma camera. Upon the validation of the gamma camera simulation model by comparing physical characteristic such as energy resolution, spatial resolution, sensitivity, and dead time, the GATE simulation of thyroid phantom imaging is carried out. Methods: A thyroid phantom is defined geometrically which comprises of 2 lobes with 80mm in diameter, 1 hot spot, and 3 cold spots. This geometry accurately resembling the actual dimensions of thyroid phantom. A planar image of 500k counts with 128x128 matrix size was acquired using simulation model and in actual experimental setup. Upon image acquisition, quantitative image analysis was performed by investigating the total number of counts in image, the contrast of the image, radioactivity distributions on image and the dimension of hot spot. Algorithm for each quantification is described in detail. The difference in estimated and actual values for both simulation and experimental setup is analyzed for radioactivity distribution and dimension of hot spot. Results: The results show that the difference between contrast level of simulation image and experimental image is within 2%. The difference in the total count between simulation and actual study is 0.4%. The results of activity estimation show that the relative difference between estimated and actual activity for experimental and simulation is 4.62% and 3.03% respectively. The deviation in estimated diameter of hot spot for both simulation and experimental study are similar which is 0.5 pixel. In conclusion, the comparisons show good agreement between the simulation and experimental data.

Keywords: gamma camera, Geant4 application of tomographic emission (GATE), Monte Carlo, thyroid imaging

Procedia PDF Downloads 271

Authors: L. Nathaniel-Wurie

Abstract:

The Sellick manoeuvre a.k.a the application of cricoid force (CF), was first described by Brian Sellick in 1961. CF is the application of digital pressure against the cricoid cartilage with the intention of posterior force causing oesophageal compression against the vertebrae. This is designed to prevent passive regurgitation of gastric contents, which is a major cause of morbidity and mortality during emergency airway management inside and outside of the hospital. To the authors knowledge, there is no universally standardised training modality and, therefore, no reliable way to examine if there are appropriate outcomes. If force is not measured during training, how can one surmise that appropriate, accurate, or precise amounts of force are being used routinely. Poor homogeneity in teaching and untested outcomes will correlate with reduced efficacy and increased adverse effects. For this study, the accuracy of force delivery in trained professionals was tested, and outcomes contrasted against a novice control and a novice study group. In this study, 20 operating department practitioners were tested (with a mean experience of 5.3years of performing CF). Subsequent contrast with 40 novice students who were randomised into one of two arms. ‘Arm A’ were explained the procedure, then shown the procedure then asked to perform CF with the corresponding force measurement being taken three times. Arm B had the same process as arm A then before being tested, they had 10, and 30 Newtons applied to their hands to increase intuitive understanding of what the required force equated to, then were asked to apply the equivalent amount of force against a visible force metre and asked to hold that force for 20 seconds which allowed direct visualisation and correction of any over or under estimation. Following this, Arm B were then asked to perform the manoeuvre, and the force generated measured three times. This study shows that there is a wide distribution of force produced by trained professionals and novices performing the procedure for the first time. Our methodology for teaching the manoeuvre shows an improved accuracy, precision, and homogeneity within the group when compared to novices and even outperforms trained practitioners. In conclusion, if this methodology is adopted, it may correlate with higher clinical outcomes, less adverse events, and more successful airway management in critical medical scenarios.

Keywords: airway, cricoid, medical education, sellick

Procedia PDF Downloads 79

Authors: Sunil Kumar, Uday C. Ghoshal

Abstract:

Background and aims: Serotonin (5-hydroxtryptamine, 5-HT) is an important factor in gut function, playing key roles in intestinal peristalsis and secretion, and in sensory signaling in the brain-gut axis. Removal from its sites of action is mediated by a specific protein called the serotonin reuptake transporter (SERT). Polymorphisms in the promoter region of the SERT gene have effects on transcriptional activity, resulting in altered 5-HT reuptake efficiency. Functional polymorphisms may underlie disturbance in gut function in individuals suffering with disorders such as irritable bowel syndrome (IBS). The aim of this study was to assess the potential association between SERT polymorphisms and the diarrhea predominant IBS (D-IBS) phenotype Subjects: A total of 36 northern Indian female patients and 55 female northern Indian healthy controls (HC) were subjected to genotyping. Methods: Leucocyte DNA of all subjects was analyzed by polymerase chain reaction based technologies for SERT polymorphisms, specifically the insertion/deletion polymorphism in the promoter (SERT-P). Statistical analysis was performed to assess association of SERT polymorphism allele with the D-IBS phenotype. Results: The frequency of distribution of SERT-P gene was comparable between female patients with IBS and HC (p = 0.086). However, frequency of SERT-P deletion/deletion genotype was significantly higher in female patients with D-IBS compared to C-IBS and A-IBS [17/19 (89.5%) vs. 4/12 (33.3%) vs. 1/5 (20%), p=0.001, respectively]. The mucosal level of serotonin was higher in D-IBS compared to C-IBS and A-IBS [Median, range (159.26, 98.78–212.1) vs. 110.4, 67.87–143.53 vs. 92.34, 78.8–166.3 pmol/mL, p=0.001, respectively]. The mucosal level of serotonin was higher in female patients with IBS with SERT-P deletion/deletion genotype compared deletion/insertion and insertion/insertion [157.65, 67.87–212.1 vs. 110.4, 78.1–143.32 vs. 100.5, 69.1–132.03 pmol/mL, p=0.001, respectively]. Patients with D-IBS with deletion/deletion genotype more often reported symptoms of abdominal pain, discomfort (p=0.025) and bloating (p=0.039). Symptoms development following lactose ingestion was strongly associated with D-IBS and SERT-P deletion/deletion genotype (p=0.004). Conclusions: Significant association was observed between D-IBS and the SERT-P deletion/deletion genotype, suggesting that the serotonin transporter is a potential candidate gene for D-IBS in women.

Keywords: serotonin, SERT, inflammatory bowel disease, genetic polymorphism

Procedia PDF Downloads 333

Authors: Chen Chuanzhi, Guo Yunyun

Abstract:

The large linear array feeding parabolic cylindrical antenna of the satellite has the ability of large-area line focusing, multi-directional beam clusters simultaneously in a certain azimuth plane and elevation plane, corresponding quickly to different orientations and different directions in a wide frequency range, dual aiming of frequency and direction, and combining space power. Therefore, the large-diameter parabolic cylindrical antenna has become one of the new development directions of spaceborne antennas. Limited by the size of the rocked fairing, the large-diameter spaceborne antenna is required to be small mass and have a deployment function. After being orbited, the antenna can be deployed by expanding and be stabilized. However, few types of structures can be used to construct large cylindrical shell structures in existing structures, which greatly limits the development and application of such antennas. Aiming at high structural efficiency, the geometrical characteristics of parabolic cylinders and mechanism topological mapping law to the expandable truss are studied, and the basic configuration of deployable truss with cylindrical shell is structured. Then a modular truss parabolic cylindrical antenna is designed in this paper. The antenna has the characteristics of stable structure, high precision of reflecting surface formation, controllable motion process, high storage rate, and lightweight, etc. On the basis of the overall configuration comprehensive theory and optimization method, the structural stiffness of the modular truss parabolic cylindrical antenna is improved. And the bearing density and impact resistance of support structure are improved based on the internal tension optimal distribution method of reflector forming. Finally, a truss-type cylindrical deployable support structure with high constriction-deployment ratio, high stiffness, controllable deployment, and low mass is successfully developed, laying the foundation for the application of large-diameter parabolic cylindrical antennas in satellite antennas.

Keywords: linear array feed antenna, truss type, parabolic cylindrical antenna, spaceborne antenna

Procedia PDF Downloads 158

Authors: Dimiter M. Dimitrov, Abdullah Sadaawi

Abstract:

The National Assessment for Schools (NAFS) in Saudi Arabia consists of standardized tests in Mathematics, Reading, and Science for school grade levels 3, 6, and 9. One main goal is to classify students into four categories of NAFS performance (minimal, basic, proficient, and advanced) by schools and the entire national sample. The NAFS scoring and equating is performed on a bounded scale (D-scale: ranging from 0 to 1) in the framework of the recently developed “D-scoring method of measurement.” The specificity of the NAFS measurement framework and data complexity presented both challenges and opportunities to (a) the estimation of score reliability for schools, (b) setting cut-scores for the classification of students into categories of performance, and (c) generating plausible values for distributions of student performance on the D-scale. The estimation of score reliability at the school level was performed in the framework of generalizability theory (GT), with students “nested” within schools and test items “nested” within test forms. The GT design was executed via a multilevel modeling syntax code in R. Cut-scores (on the D-scale) for the classification of students into performance categories was derived via a recently developed method of standard setting, referred to as “Response Vector for Mastery” (RVM) method. For each school, the classification of students into categories of NAFS performance was based on distributions of plausible values for the students’ scores on NAFS tests by grade level (3, 6, and 9) and subject (Mathematics, Reading, and Science). Plausible values (on the D-scale) for each individual student were generated via random selection from a statistical logit-normal distribution with parameters derived from the student’s D-score and its conditional standard error, SE(D). All procedures related to D-scoring, equating, generating plausible values, and classification of students into performance levels were executed via a computer program in R developed for the purpose of NAFS data analysis.

Keywords: large-scale assessment, reliability, generalizability theory, plausible values

Procedia PDF Downloads 18

Authors: Muluken Biadgelegn Wollele, Mebratu Assaye Mengistu

Abstract:

Nanotechnology has created new opportunities for improving industrial efficiency and performance. One of the proposed approaches to improving the effectiveness of temperature exchangers is the use of nanofluids to improve heat transfer performance. The thermal conductivity of nanoparticles, as well as their size, diameter, and volume concentration, all played a role in influencing the rate of heat transfer. Nanofluids are commonly used in automobiles, energy storage, electronic component cooling, solar absorbers, and nuclear reactors. Convective heat transfer must be improved when designing thermal systems in order to reduce heat exchanger size, weight, and cost. Using roughened surfaces to promote heat transfer has been tried several times. Thus, both active and passive heat transfer methods show potential in terms of heat transfer improvement. There will be an added advantage of enhanced heat transfer due to the two methods adopted; however, pressure drop must be considered during flow. Thus, the current research aims to increase heat transfer by adding a twisted tap insert in a plain tube using a working fluid hybrid nanofluid (Al₂O₃-Cu) with a base fluid of water. A circular duct with inserts, a tube length of 3 meters, a hydraulic diameter of 0.01 meters, and tube walls with a constant heat flux of 20 kW/m² and a twist ratio of 125 was used to investigate Al₂O₃-Cu/H₂O hybrid nanofluid with inserts. The temperature distribution is better than with conventional tube designs due to stronger tangential contact and swirls in the twisted tape. The Nusselt number values of plain twisted tape tubes are 1.5–2.0 percent higher than those of plain tubes. When twisted tape is used instead of plain tube, performance evaluation criteria improve by 1.01 times. A heat exchanger that is useful for a number of heat exchanger applications can be built utilizing a mixed flow of analysis that incorporates passive and active methodologies.

Keywords: nanofluids, active method, passive method, Nusselt number, performance evaluation criteria

Procedia PDF Downloads 74

Authors: Reshan Perera, Sarith Munasinghe, Himali Lakshika, Yasith Perera, Hasitha Walakadawattage, Udayanga Hemapala

Abstract:

This research presents a reconfigurable architecture for residential microgrid systems utilizing Z-Source Inverter (ZSI) to optimize solar photovoltaic (SPV) system utilization and enhance grid resilience. The proposed system addresses challenges associated with high solar power penetration through various modes, including current control, voltage-frequency control, and reactive power control. It ensures uninterrupted power supply during grid faults, providing flexibility and reliability for grid-connected SPV customers. Challenges and opportunities in reactive power control for microgrids are explored, with simulation results and case studies validating proposed strategies. From a control and power perspective, the ZSI-based inverter enhances safety, reduces failures, and improves power quality compared to traditional inverters. Operating seamlessly in grid-connected and islanded modes guarantees continuous power supply during grid disturbances. Moreover, the research addresses power quality issues in long distribution feeders during off-peak and night-peak hours or fault conditions. Using the Distributed Static Synchronous Compensator (DSTATCOM) for voltage stability, the control objective is nighttime voltage regulation at the Point of Common Coupling (PCC). In this mode, disconnection of PV panels, batteries, and the battery controller allows the ZSI to operate in voltage-regulating mode, with critical loads remaining connected. The study introduces a structured controller for Reactive Power Controlling mode, contributing to a comprehensive and adaptable solution for residential microgrid systems. Mathematical modeling and simulations confirm successful maximum power extraction, controlled voltage, and smooth voltage-frequency regulation.

Keywords: reconfigurable architecture, solar photovoltaic, microgrids, z-source inverter, STATCOM, power quality, battery storage system

Procedia PDF Downloads 7

Authors: Shimhanda M. N., Mogomotsi P. K., Thakadu O. T., Rutina L. P.

Abstract:

Wildlife tourism (WT) in communal conservancies has the potential to contribute significantly to sustainable rural development. However, understanding local perceptions, promoting participation, and addressing stakeholder concerns are all required for sustainability. This study looks at stakeholder perceptions of WT in conservancies near protected areas in Namibia's Zambezi region, specifically the Mudumu North Complex. A mixed-methods approach was employed to collect data from 356 households using stratified sampling. Qualitative data was gathered through six focus group discussions and 22 key informant interviews. Quantitative analysis, using descriptive statistics and Spearman correlation, investigated socio-demographic influences on WT perceptions, while qualitative data were subjected to thematic analysis to identify key themes. Results revealed high awareness and generally positive perceptions of WT, particularly in Mashi Conservancy, which benefits from diverse tourism activities and joint ventures with lodges. Kwandu and Kyaramacan, which rely heavily on consumptive tourism, had lower awareness and perceived benefits. Human-wildlife conflict emerged as a persistent issue, especially in Kwandu and Mashi, where crop damage and wildlife interference undermined community support for WT. Younger, more educated, and employed individuals held more positive attitudes towards WT. The study highlights the importance of recognising community heterogeneity and tailoring WT strategies to meet diverse needs, including HWC mitigation. Policy implications include increasing community engagement, ensuring equitable benefit distribution, and implementing inclusive tourism strategies that promote long-term sustainability. These findings are critical for developing long-term WT models that address local challenges, encourage community participation, and contribute to socioeconomic development and conservation goals.

Keywords: sustainable tourism, stakeholder perceptions, community involvement, socio-economic development

Procedia PDF Downloads 16

Authors: Loonibha Manandhar, Rajendra Bhandari, Kumud Raj Kafle

Abstract:

Nepal’s Terai region is a part of the Ganges river basin which is one of the most disaster-prone areas of the world, with recurrent monsoon flooding causing millions in damage and the death and displacement of hundreds of people and households every year. The vulnerability of human settlements to natural disasters such as floods is increasing, and mapping changes in land use practices and hydro-geological parameters is essential in developing resilient communities and strong disaster management policies. The objective of this study was to develop a flood hazard zonation map of Orai Khola watershed and map the decadal land use/land cover dynamics of the watershed. The watershed area was delineated using SRTM DEM, and LANDSAT images were classified into five land use classes (forest, grassland, sediment and bare land, settlement area and cropland, and water body) using pixel-based semi-automated supervised maximum likelihood classification. Decadal changes in each class were then quantified using spatial modelling. Flood hazard mapping was performed by assigning weights to factors slope, rainfall distribution, distance from the river and land use/land cover on the basis of their estimated influence in causing flood hazard and performing weighed overlay analysis to identify areas that are highly vulnerable. The forest and grassland coverage increased by 11.53 km² (3.8%) and 1.43 km² (0.47%) from 1996 to 2016. The sediment and bare land areas decreased by 12.45 km² (4.12%) from 1996 to 2016 whereas settlement and cropland areas showed a consistent increase to 14.22 km² (4.7%). Waterbody coverage also increased to 0.3 km² (0.09%) from 1996-2016. 1.27% (3.65 km²) of total watershed area was categorized into very low hazard zone, 20.94% (60.31 km²) area into low hazard zone, 37.59% (108.3 km²) area into moderate hazard zone, 29.25% (84.27 km²) area into high hazard zone and 31 villages which comprised 10.95% (31.55 km²) were categorized into high hazard zone area.

Keywords: flood hazard, land use/land cover, Orai river, supervised maximum likelihood classification, weighed overlay analysis

Procedia PDF Downloads 352

Authors: Hamza Javar Magnier, Leslie V. Woodcock

Abstract:

We report extensive molecular dynamics (MD) computational investigations into the thermodynamic description of supercritical properties for a model fluid that is the simplest realistic representation of atoms or molecules. The pair potential is a hard-sphere repulsion of diameter σ with a very short attraction of length λσ. When λ = 1.005 the range is so short that the model atoms are referred to as “adhesive spheres”. Molecular dimers, trimers …etc. up to large clusters, or droplets, of many adhesive-sphere atoms are unambiguously defined. This then defines percolation transitions at the molecular level that bound the existence of gas and liquid phases at supercritical temperatures, and which define the existence of a supercritical mesophase. Both liquid and gas phases are seen to terminate at the loci of percolation transitions, and below a second characteristic temperature (Tc2) are separated by the supercritical mesophase. An analysis of the distribution of clusters in gas, meso- and liquid phases confirms the colloidal nature of this mesophase. The general phase behaviour is compared with both experimental properties of the water-steam supercritical region and also with formally exact cluster theory of Mayer and Mayer. Both are found to be consistent with the present findings that in this system the supercritical mesophase narrows in density with increasing T > Tc and terminates at a higher Tc2 at a confluence of the primary percolation loci. The expended plot of the MD data points in the mesophase of 7 critical and supercritical isotherms in highlight this narrowing in density of the linear-slope region of the mesophase as temperature is increased above the critical. This linearity in the mesophase implies the existence of a linear combination rule between gas and liquid which is an extension of the Lever rule in the subcritical region, and can be used to obtain critical parameters without resorting to experimental data in the two-phase region. Using this combination rule, the calculated critical parameters Tc = 0.2007 and Pc = 0.0278 are found be agree with the values found by of Largo and coworkers. The properties of this supercritical mesophase are shown to be consistent with an alternative description of the phenomenon of critical opalescence seen in the supercritical region of both molecular and colloidal-protein supercritical fluids.

Keywords: critical opalescence, supercritical, square-well, percolation transition, critical parameters.

Procedia PDF Downloads 521

Authors: Ahmed G. Mahgoub, Dahlia H. Hafez, Mostafa A. Abu Kiefa

Abstract:

The Cone Penetration Test (CPT) is a common in-situ test which generally investigates a much greater volume of soil more quickly than possible from sampling and laboratory tests. Therefore, it has the potential to realize both cost savings and assessment of soil properties rapidly and continuously. The principle objective of this paper is to demonstrate the feasibility and efficiency of using artificial neural networks (ANNs) to predict the soil angle of internal friction (Φ) and the soil modulus of elasticity (E) from CPT results considering the uncertainties and non-linearities of the soil. In addition, ANNs are used to study the influence of different parameters and recommend which parameters should be included as input parameters to improve the prediction. Neural networks discover relationships in the input data sets through the iterative presentation of the data and intrinsic mapping characteristics of neural topologies. General Regression Neural Network (GRNN) is one of the powerful neural network architectures which is utilized in this study. A large amount of field and experimental data including CPT results, plate load tests, direct shear box, grain size distribution and calculated data of overburden pressure was obtained from a large project in the United Arab Emirates. This data was used for the training and the validation of the neural network. A comparison was made between the obtained results from the ANN's approach, and some common traditional correlations that predict Φ and E from CPT results with respect to the actual results of the collected data. The results show that the ANN is a very powerful tool. Very good agreement was obtained between estimated results from ANN and actual measured results with comparison to other correlations available in the literature. The study recommends some easily available parameters that should be included in the estimation of the soil properties to improve the prediction models. It is shown that the use of friction ration in the estimation of Φ and the use of fines content in the estimation of E considerable improve the prediction models.

Keywords: angle of internal friction, cone penetrating test, general regression neural network, soil modulus of elasticity

Procedia PDF Downloads 415

Authors: Gal Zagron, Nitza Abramson, Deena R. Zimmerman, Chen Stein-Zamir

Abstract:

Background: Salmonella enteritidis is a common cause of foodborne outbreaks, primarily associated with poultry eggs. S. enteritidis This is the only Salmonella type that is found inside the eggshell. A rise in Salmonella enteritidis notifications was noted in spring 2017. Aims: The aim of this study is to describe the epidemiological investigation of the outbreak in the Jerusalem district, along with the containment measures taken. Methods: This study is a population-based epidemiological study with a description of environmental control activities. Results: During the months May - July, 2017 848 salmonellosis cases were reported to the Jerusalem district health office compared to 294 cases May - July 2016. Salmonella enteritidis was isolated in 58% of reported cases. Clusters and outbreaks ( > 2 cases) were reported among nursery schools, nursing homes, persons residing in one kibbutz and several cases in different food service establishments in the Jerusalem district. Epidemiological investigations revealed eggs consumption as a common feature among the cases (uncooked or undercooked eggs in most cases). A national investigation among egg suppliers revealed that most cases consumed eggs provided by a single provider with isolation of Salmonella enteritidis at the source as well. Containment measures were taken to control the epidemic including distributing information via electronic and written media to the public, searching for all egg distribution centers, informing local authorities, the poultry council and food stores. The eggs originating from the provider were recalled and extinguished. Written instructions to all food preparation facilities in the district were distributed regarding the proper storage and preparation of eggs. The number of reported cases declined and the outbreak vanished during correlating months of 2018. Conclusions: The investigation of Salmonella enteritidis outbreaks should include epidemiological and laboratory investigations, tracing the source of the eggs and testing the eggs and the source of eggs. Health education activities are essential as to the proper handling of eggs and egg products aiming to minimize susceptibility to Salmonella infection.

Keywords: epidemiological investigation, food-borne disease, food safety, Salmonella enteritidis

Procedia PDF Downloads 143

Authors: Abdul-Dahiru El-Yuguda, Saka Saheed Baba, Tawa Monilade Adisa, Mustapha Bala Abubakar

Abstract:

Background: Chikungunya (CHIK) virus, a previously anecdotally described arbovirus, is now assuming a worldwide public health burden. The CHIK virus infection is characterized by potentially life threatening and debilitating arthritis in addition to the high fever, arthralgia, myalgia, headache and rash. Method: Three hundred and seventy (370) serum samples were collected from outpatients with febrile illness attending University of Maiduguri Teaching Hospital, Nigeria, and was used to detect for Chikungunya (CHIK) virus IgG and IgM antibodies using the Enzyme Linked Immunosorbent Assays (ELISAs). Result: Out of the 370 sera tested, 39 (10.5%) were positive for presence of CHIK virus antibodies. A total of 24 (6.5%) tested positive for CHIK virus IgM only while none (0.0%) was positive for presence of CHIK virus IgG only and 15 (4.1%) of the serum samples were positive for both IgG and IgM antibodies. A significant difference (p<0.0001) was observed in the distribution of CHIK virus antibodies in relation to gender. The males had prevalence of 8.5% IgM antibodies as against 4.6% observed in females. On the other hand 4.6% of the females were positive for concurrent CHIK virus IgG and IgM antibodies when compared to a prevalence of 3.4% observed in males. Only the age groups ≤ 60 years and the undisclosed age group were positive for presence of CHIK virus IgG and/or IgM antibodies. No significant difference (p>0.05) was observed in the seasonal prevalence of CHIK virus antibodies among the study subjects Analysis of the prevalence of CHIK virus antibodies in relation to clinical presentation (as observed by Clinicians) of the patients revealed that headache and fever were the most frequently encountered ailments. Conclusion: The CHIK virus IgM and concurrent IgM and IgG antibody prevalence rates of 6.5% and 4.1% observed in this study indicates a current infection and the lack of IgG antibody alone observed shows that the infection is not endemic but sporadic. Recommendation: Further studies should be carried to establish the seasonal prevalence of CHIK virus infection vis-à-vis vector dynamics in the study area. A comprehensive study need to be carried out on the molecular characterization of the CHIK virus circulating in Nigeria with a view to developing CHIK virus vaccine.

Keywords: Chikungunya virus, IgM and IgG antibodies, febrile patients, enzyme linked immunosorbent assay

Procedia PDF Downloads 389

Authors: Subhankar Kumar Sarkar

Abstract:

Beetles of the subfamily Dynastinae under the family Scarabaeidae of the insect order Coleoptera are popularly known as ‘Rhinoceros beetles’ because of the characteristic horn borne by the males on their head. These horns are dedicated in mating battle against other males and have evolved as a result of phenotypic plasticity. Scarabaeidae is the largest of all families under Coleoptera and is composed of 11 subfamilies, of which the subfamily Dynastinae is represented by approximately 300 species. Some of these beetles have been reported to cause considerable damage to agriculture and forestry both in their larval and adult stages, while many of them are beneficial as they pollinate plants and recycle plant materials. Eastern Himalayas is regarded as one of the 35 biodiversity hotspot zones of the world and one of the four of India, which is exhibited by its rich and megadiverse tropical forests. However, our knowledge on the faunal diversity of these forests is very limited, particularly for the insect fauna. One such tropical forest of Eastern Himalayas is the ‘Buxa Tiger Reserve’ located between latitudes 26°30” to 26°55” North and Longitudes 89°20” to 89˚35” East of India and occupies an area of about 759.26 square kilometers. It is with this background an attempt has been made to explore the insect fauna of the forest. Insect sampling was carried out in each beat and range of Buxa Tiger Reserve in all the three seasons viz, Premonsoon, Monsoon, and Postmonsoon. Sample collections were done by sweep nets, hand picking technique and pit fall traps. UV light trap was used to collect the nocturnal insects. Morphological examinations of the collected samples were carried out with Stereozoom Binocular Microscopes (Zeiss SV6 and SV11) and were identified up to species level with the aid of relevant literature. Survey of the insect fauna of the forest resulted in the recognition of 76 scarab species, of which 8 belong to the subfamily dealt herein. Each of the 8 species represents a separate genus. The forest is dominated by the members of Xylotrupes gideon (Linnaeus) as is represented by highest number of individuals. The recorded taxa show about 12% endemism and are of mainly oriental in distribution. Premonsoon is the most favorable season for their occurrence and activity followed by Monsoon and Postmonsoon.

Keywords: Dynastinae, Scarabaeidae, diversity, Buxa Tiger Reserve

Procedia PDF Downloads 189

Authors: D. H. Tejavathi

Abstract:

Medicinal plants are globally valuable sources of herbal products. Wild populations of many medicinal plants are facing threat of extinction because of their narrow distribution, endemicity, and degradation of specific habitats. Micropropagation is an established in vitro technique by which large number of clones can be obtained from a small bit of explants in a short span of time within a limited space. Mycorrhization can minimize the transient transplantation shock, experienced by the micropropagated plants when they are transferred from lab to land. AM fungal association improves the physiological status of the host plants through better uptake of water and nutrients, particularly phosphorus. Consequently, the growth performance and biosynthesis of active principles are significantly enhanced in AM fungal treated plants. Bacopa monnieri, Andrographis paniculata, Agave vera-curz, Drymaria cordata and Majorana hortensis, important medicinal plants used in various indigenous systems of medicines, are selected for the present study. They form the main constituents of many herbal formulations. Standard in vitro techniques were followed to obtain the micropropagated plants. Shoot tips and nodal segments were used as explants. Explants were cultured on Murashige and Skoog, and Phillips and Collins media supplemented with various combinations of growth regulators. Multiple shoots were obtained on a media containing both auxins and cytokinins at various concentrations and combinations. Multiple shoots were then transferred to rooting media containing auxins for root induction. Thus, obtained in vitro regenerated plants were subjected to brief acclimatization before transferring them to land. One-month-old in vitro plants were treated with AM fungi, and the symbiotic effect on the overall growth parameters was analyzed. It was found that micropropagation coupled with mycorrhization has significant effect on the enhancement of biomass and biosynthesis of active principles in these selected medicinal plants. In vitro techniques coupled with mycorrhization have opened a possibility of obtaining better clones in respect of enhancement of biomass and biosynthesis of active principles. Beneficial effects of AM fungal association with medicinal plants are discussed.

Keywords: cultivation, medicinal plants, micropropagation, mycorrhization

Procedia PDF Downloads 171

Authors: Alireza Monzavi Chaleshtari, Maryam Aliakbari

Abstract:

Objective: The aim of this study was to investigate the prediction of child attachment style based on a positive and safe combination parenting method mediated by maternal attachment styles in children with attention deficit hyperactivity disorder. Method: The design of the present study was descriptive of correlation and structural equations and applied in terms of purpose. The population of this study includes all children with attention deficit hyperactivity disorder living in Chaharmahal and Bakhtiari province and their mothers. The sample size of the above study includes 165children with attention deficit hyperactivity disorder in Chaharmahal and Bakhtiari province with their mothers, who were selected by purposive sampling method based on the inclusion criteria. The obtained data were analyzed in two sections of descriptive and inferential statistics. In the descriptive statistics section, statistical indices of mean, standard deviation, frequency distribution table and graph were used. In the inferential section, according to the nature of the hypotheses and objectives of the research, the data were analyzed using Pearson correlation coefficient tests, Bootstrap test and structural equation model. findings:The results of structural equation modeling showed that the research models fit and showed a positive and safe combination parenting style mediated by the mother attachment style has an indirect effect on the child attachment style. Also, a positive and safe combined parenting style has a direct relationship with child attachment style, and She has a mother attachment style. Conclusion:The results and findings of the present study show that there is a significant relationship between positive and safe combination parenting methods and attachment styles of children with attention deficit hyperactivity disorder with maternal attachment style mediation. Therefore, it can be expected that parents using a positive and safe combination232 parenting method can effectively lead to secure attachment in children with attention deficit hyperactivity disorder.

Keywords: child attachment style, positive and safe parenting, maternal attachment style, ADHD

Procedia PDF Downloads 66

Authors: Sungpil Ha, Ju Yong Kang, Sangbaek Park, Seung-Ju Lee, Soo-Won Chae

Abstract:

The growing number of obese patients in aging societies has led to an increase in the number of patients with knee medial osteoarthritis (OA). Artificial joint insertion is the most common treatment for knee medial OA. Surgery is effective for patients with serious arthritic symptoms, but it is costly and dangerous. It is also inappropriate way to prevent a disease as an early stage. Therefore Non-operative treatments such as toe-in gait are proposed recently. Toe-in gait is one of non-surgical interventions, which restrain the progression of arthritis and relieves pain by reducing knee adduction moment (KAM) to facilitate lateral distribution of load on to knee medial cartilage. Numerous studies have measured KAM in various foot progression angle (FPA), and KAM data could be obtained by motion analysis. However, variations in stress at knee cartilage could not be directly observed or evaluated by these experiments of measuring KAM. Therefore, this study applied motion analysis to major gait points (1st peak, mid –stance, 2nd peak) with regard to FPA, and to evaluate the effects of FPA on the human lower extremity, the finite element (FE) method was employed. Three types of gait analysis (toe-in, toe-out, baseline gait) were performed with markers placed at the lower extremity. Ground reaction forces (GRF) were obtained by the force plates. The forces associated with the major muscles were computed using GRF and marker trajectory data. MRI data provided by the Visible Human Project were used to develop a human lower extremity FE model. FE analyses for three types of gait simulations were performed based on the calculated muscle force and GRF. We observed the maximum stress point during toe-in gait was lower than the other types, by comparing the results of FE analyses at the 1st peak across gait types. This is the same as the trend exhibited by KAM, measured through motion analysis in other papers. This indicates that the progression of knee medial OA could be suppressed by adopting toe-in gait. This study integrated motion analysis with FE analysis. One advantage of this method is that re-modeling is not required even with changes in posture. Therefore another type of gait simulation or various motions of lower extremity can be easily analyzed using this method.

Keywords: finite element analysis, gait analysis, human model, motion capture

Procedia PDF Downloads 335

Authors: Alma Mendoza-Ponce, Rogelio Corona-Núñez, Florian Kraxner

Abstract:

Mexico is a megadiverse country and it has nearly halved its natural vegetation in the last century due to agricultural and livestock expansion. Impacts of land use cover change and climate change are unevenly distributed and spatial prioritization to minimize the affectations on biodiversity is crucial. Global and national efforts for prioritizing biodiversity conservation show that ~33% to 45% of Mexico should be protected. The width of these targets makes difficult to lead resources. We use a framework based on vulnerability and irreplaceability to prioritize conservation efforts in Mexico. Vulnerability considered exposure, sensitivity and adaptive capacity under two scenarios (business as usual, BAU based, on the SSP2 and RCP 4.5 and a Green scenario, based on the SSP1 and the RCP 2.6). Exposure to land use is the magnitude of change from natural vegetation to anthropogenic covers while exposure to climate change is the difference between current and future values for both scenarios. Sensitivity was considered as the number of endemic species of terrestrial vertebrates which are critically endangered and endangered. Adaptive capacity is used as the ration between the percentage of converted area (natural to anthropogenic) and the percentage of protected area at municipality level. The results suggest that by 2050, between 11.6 and 13.9% of Mexico show vulnerability ≥ 50%, and by 2070, between 12.0 and 14.8%, in the Green and BAU scenario, respectively. From an ecosystem perspective cloud forests, followed by tropical dry forests, natural grasslands and temperate forests will be the most vulnerable (≥ 50%). Amphibians are the most threatened vertebrates; 62% of the endemic amphibians are critically endangered or endangered while 39%, 12% and 9% of the mammals, birds, and reptiles, respectively. However, the distribution of these amphibians counts for only 3.3% of the country, while mammals, birds, and reptiles in these categories represent 10%, 16% and 29% of Mexico. There are 5 municipalities out of the 2,457 that Mexico has that represent 31% of the most vulnerable areas (70%).These municipalities account for 0.05% of Mexico. This multiscale approach can be used to address resources to conservation targets as ecosystems, municipalities or species considering land use cover change, climate change and biodiversity uniqueness.

Keywords: biodiversity, climate change, land use change, Mexico, vulnerability

Procedia PDF Downloads 167

Authors: Marwa Ben Khalifa, Zeineb Ben Salem, Wissem Frikha

Abstract:

The purpose of the present work is to study the consolidation behavior of highly compressible Tunis soft soil “TSS” by means of prefabricated vertical drains (PVD’s) associated to preloading based on laboratory and field investigations. In the first hand, the field performance of PVD’s on the layer of Tunis soft soil was analysed based on the case study of the construction of embankments of “Radès la Goulette” bridge project. PVD’s Geosynthetics drains types were installed with triangular grid pattern until 10 m depth associated with step-by-step surcharge. The monitoring of the soil settlement during preloading stage for Radès La Goulette Bridge project was provided by an instrumentation composed by various type of tassometer installed in the soil. The distribution of water pressure was monitored through piezocone penetration. In the second hand, a laboratory reduced tests are performed on TSS subjected also to preloading and improved with PVD's Mebradrain 88 (Mb88) type. A specific test apparatus was designed and manufactured to study the consolidation. Two series of consolidation tests were performed on TSS specimens. The first series included consolidation tests for soil improved by one central drain. In thesecond series, a triangular mesh of three geodrains was used. The evolution of degree of consolidation and measured settlements versus time derived from laboratory tests and field data were presented and discussed. The obtained results have shown that PVD’s have considerably accelerated the consolidation of Tunis soft soil by shortening the drainage path. The model with mesh of three drains gives results more comparative to field one. A longer consolidation time is observed for the cell improved by a single central drain. A comparison with theoretical analysis, basically that of Barron (1948) and Carillo (1942), was presented. It’s found that these theories overestimate the degree of consolidation in the presence of PVD.

Keywords: tunis soft soil, prefabricated vertical drains, acceleration of consolidation, dissipation of excess pore water pressures, radès bridge project, barron and carillo’s theories

Procedia PDF Downloads 127

Authors: Ana Elisa Ribeiro Costa, Sónia Daniela Ferreira Miranda, João Pedro De Carvalho Pereira, João Carlos Simões Bernardo

Abstract:

Elastomeric thermoplastics (TPEs) have been widely used in the footwear industry over the years. Recently this industry has been requesting materials that can combine lightweight and high abrasion resistance. Although there are blowing agents on the market to improve the lightweight, when these are incorporated into molten polymers during the extrusion or injection molding, it is necessary to have some specific processing conditions (e.g. effect of temperature and hydrodynamic stresses) to obtain good properties and acceptable surface appearance on the final products. Therefore, it is a great advantage for the compounder industry to acquire compounds that already include the blowing agents. In this way, they can be handled and processed under the same conditions as a conventional raw material. In this work, the expandable TPEs compounds, namely a TPU and a SEBS, with the incorporation of blowing agents, have been developed through a co-rotating modular twin-screw parallel extruder. Different blowing agents such as thermo-expandable microspheres and an azodicarbonamide were selected and different screw configurations and temperature profiles were evaluated since these parameters have a particular influence on the expansion inhibition of the blowing agents. Furthermore, percentages of incorporation were varied in order to investigate their influence on the final product properties. After the extrusion of these compounds, expansion was tested by the injection process. The mechanical and physical properties were characterized by different analytical methods like tensile, flexural and abrasive tests, determination of hardness and density measurement. Also, scanning electron microscopy (SEM) was performed. It was observed that it is possible to incorporate the blowing agents on the TPEs without their expansion on the extrusion process. Only with reprocessing (injection molding) did the expansion of the agents occur. These results are corroborated by SEM micrographs, which show a good distribution of blowing agents in the polymeric matrices. The other experimental results showed a good mechanical performance and its density decrease (30% for SEBS and 35% for TPU). This study suggested that it is possible to develop optimized compounds for footwear applications (e.g., sole shoes), which only will be able to expand during the injection process.

Keywords: blowing agents, expandable thermoplastic elastomeric compounds, low density, footwear applications

Procedia PDF Downloads 206