Search results for: erosion and wear volume
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 3610

Search results for: erosion and wear volume

2440 Effect of Neem (Aziradicta Indica) Leaf Meal on Growth Performance, Haematology and Serum Biochemistry Indices of Broilers Not Administered Vaccines and Antibiotics

Authors: Ugwuowo Leonard Chidi, Oparaji Chetachukwu Jecinta., Ogidi Chibuzor Agafenachukwu, Onuoha Rebecca Obianuju

Abstract:

This experiment was conducted to investigate the growth performance, haematology and serum biochemistry indices of broiler birds fed diets containing Neem leaf meal. A total of 96 unsexed day-old broiler birds were allocated to four treatments of T1, T2, T3 and T4 and replicated three times with eight birds per replicate in a Completely Randomized Design. The treatments were diets containing 2.0, 4.0, 6.0 and 8.0% Neem leaf meal respectively. Growth performances, packed cell volume, red blood cell count, haemoglobin, white blood cell count, lymphocytes, mean corpuscular volume, mean corpuscular haemoglobin concentration, platelet count, aspartate amino transaminase, alanine amino transaminase, alkaline phosphate, cholesterol, albumin, globulin, urea, glucose, total protein and creatinine were evaluated. Results showed that there were no significant differences (P>0.05) in all the growth performance parameters among the treatments. The results of the experiment showed that there were significant differences (P<0.05) in all the heamatological and serum biochemistry parameters at finisher phases. Mean corpuscular volume, white blood cell count, lymphocytes, red blood cell count, haemoglobin, platelet count, creatinine and triglyceride increased and were highest in treatment two while treatment four had the least values in mean corpuscular volume, urea, white blood cell, haemoglobin and triglyceride. This implies that the levels of inclusion of Neem leaf meal in this experiment did not affect the growth performance of the broiler chicks but the haematological and serum biochemistry indices were affected. Treatment two with a 4% inclusion level of Neem leaf meal has shown the capacity to replace vaccines and antibiotics in broilers due to the positive effects it had on both the haematological and serum biochemistry.

Keywords: leaf meal, broiler, Aziradicta indica, serum biochemistry, haematology

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2439 Numerical Investigation of Pressure and Velocity Field Contours of Dynamics of Drop Formation

Authors: Pardeep Bishnoi, Mayank Srivastava, Mrityunjay Kumar Sinha

Abstract:

This article represents the numerical investigation of the pressure and velocity field variation of the dynamics of pendant drop formation through a capillary tube. Numerical simulations are executed using volume of fluid (VOF) method in the computational fluid dynamics (CFD). In this problem, Non Newtonian fluid is considered as dispersed fluid whereas air is considered as a continuous fluid. Pressure contours at various time steps expose that pressure varies nearly hydrostatically at each step of the dynamics of drop formation. A result also shows the pressure variation of the liquid droplet during free fall in the computational domain. The evacuation of the fluid from the necking region is also shown by the contour of the velocity field. The role of surface tension in the Pressure contour of the dynamics of drop formation is also studied.

Keywords: pressure contour, surface tension, volume of fluid, velocity field

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2438 Optimizing Production Yield Through Process Parameter Tuning Using Deep Learning Models: A Case Study in Precision Manufacturing

Authors: Tolulope Aremu

Abstract:

This paper is based on the idea of using deep learning methodology for optimizing production yield by tuning a few key process parameters in a manufacturing environment. The study was explicitly on how to maximize production yield and minimize operational costs by utilizing advanced neural network models, specifically Long Short-Term Memory and Convolutional Neural Networks. These models were implemented using Python-based frameworks—TensorFlow and Keras. The targets of the research are the precision molding processes in which temperature ranges between 150°C and 220°C, the pressure ranges between 5 and 15 bar, and the material flow rate ranges between 10 and 50 kg/h, which are critical parameters that have a great effect on yield. A dataset of 1 million production cycles has been considered for five continuous years, where detailed logs are present showing the exact setting of parameters and yield output. The LSTM model would model time-dependent trends in production data, while CNN analyzed the spatial correlations between parameters. Models are designed in a supervised learning manner. For the model's loss, an MSE loss function is used, optimized through the Adam optimizer. After running a total of 100 training epochs, 95% accuracy was achieved by the models recommending optimal parameter configurations. Results indicated that with the use of RSM and DOE traditional methods, there was an increase in production yield of 12%. Besides, the error margin was reduced by 8%, hence consistent quality products from the deep learning models. The monetary value was annually around $2.5 million, the cost saved from material waste, energy consumption, and equipment wear resulting from the implementation of optimized process parameters. This system was deployed in an industrial production environment with the help of a hybrid cloud system: Microsoft Azure, for data storage, and the training and deployment of their models were performed on Google Cloud AI. The functionality of real-time monitoring of the process and automatic tuning of parameters depends on cloud infrastructure. To put it into perspective, deep learning models, especially those employing LSTM and CNN, optimize the production yield by fine-tuning process parameters. Future research will consider reinforcement learning with a view to achieving further enhancement of system autonomy and scalability across various manufacturing sectors.

Keywords: production yield optimization, deep learning, tuning of process parameters, LSTM, CNN, precision manufacturing, TensorFlow, Keras, cloud infrastructure, cost saving

Procedia PDF Downloads 31
2437 Topology Optimization of Heat Exchanger Manifolds for Aircraft

Authors: Hanjong Kim, Changwan Han, Seonghun Park

Abstract:

Heat exchanger manifolds in aircraft play an important role in evenly distributing the fluid entering through the inlet to the heat transfer unit. In order to achieve this requirement, the manifold should be designed to have a light weight by withstanding high internal pressure. Therefore, this study aims at minimizing the weight of the heat exchanger manifold through topology optimization. For topology optimization, the initial design space was created with the inner surface extracted from the currently used manifold model and with the outer surface having a dimension of 243.42 mm of X 74.09 mm X 65 mm. This design space solid model was transformed into a finite element model with a maximum tetrahedron mesh size of 2 mm using ANSYS Workbench. Then, topology optimization was performed under the boundary conditions of an internal pressure of 5.5 MPa and the fixed support for rectangular inlet boundaries by SIMULIA TOSCA. This topology optimization produced the minimized finial volume of the manifold (i.e., 7.3% of the initial volume) based on the given constraints (i.e., 6% of the initial volume) and the objective function (i.e., maximizing manifold stiffness). Weight of the optimized model was 6.7% lighter than the currently used manifold, but after smoothing the topology optimized model, this difference would be bigger. The current optimized model has uneven thickness and skeleton-shaped outer surface to reduce stress concentration. We are currently simplifying the optimized model shape with spline interpolations by reflecting the design characteristics in thickness and skeletal structures from the optimized model. This simplified model will be validated again by calculating both stress distributions and weight reduction and then the validated model will be manufactured using 3D printing processes.

Keywords: topology optimization, manifold, heat exchanger, 3D printing

Procedia PDF Downloads 248
2436 Application of the Finite Window Method to a Time-Dependent Convection-Diffusion Equation

Authors: Raoul Ouambo Tobou, Alexis Kuitche, Marcel Edoun

Abstract:

The FWM (Finite Window Method) is a new numerical meshfree technique for solving problems defined either in terms of PDEs (Partial Differential Equation) or by a set of conservation/equilibrium laws. The principle behind the FWM is that in such problem each element of the concerned domain is interacting with its neighbors and will always try to adapt to keep in equilibrium with respect to those neighbors. This leads to a very simple and robust problem solving scheme, well suited for transfer problems. In this work, we have applied the FWM to an unsteady scalar convection-diffusion equation. Despite its simplicity, it is well known that convection-diffusion problems can be challenging to be solved numerically, especially when convection is highly dominant. This has led researchers to set the scalar convection-diffusion equation as a benchmark one used to analyze and derive the required conditions or artifacts needed to numerically solve problems where convection and diffusion occur simultaneously. We have shown here that the standard FWM can be used to solve convection-diffusion equations in a robust manner as no adjustments (Upwinding or Artificial Diffusion addition) were required to obtain good results even for high Peclet numbers and coarse space and time steps. A comparison was performed between the FWM scheme and both a first order implicit Finite Volume Scheme (Upwind scheme) and a third order implicit Finite Volume Scheme (QUICK Scheme). The results of the comparison was that for equal space and time grid spacing, the FWM yields a much better precision than the used Finite Volume schemes, all having similar computational cost and conditioning number.

Keywords: Finite Window Method, Convection-Diffusion, Numerical Technique, Convergence

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2435 Importance of Determining the Water Needs of Crops in the Management of Water Resources in the Province of Djelfa

Authors: Imessaoudene Y., Mouhouche B., Sengouga A., Kadir M.

Abstract:

The objective of this work is to determine the virtual water of main crops grown in the province of Djelfa and water use efficiency (W.U.E.), Which is essential to approach the application and better integration with the offer in the region. In the case of agricultural production, virtual water is the volume of water evapo-transpired by crops. It depends on particular on the expertise of its producers and its global production area, warm and dry climates induce higher consumption. At the scale of the province, the determination of the quantities of virtual water is done by calculating the unit water requirements related to water irrigated hectare and total rainfall over the crop using the Cropwat 8.0 F.A.O. software. Quantifying the volume of agricultural virtual water of crops practiced in the study area demonstrates the quantitative importance of these volumes of water in terms of available water resources in the province, so the advantages which can be the concept of virtual water as an analysis tool and decision support for the management and distribution of water in scarcity situation.

Keywords: virtual water, water use efficiency, water requirements, Djelfa

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2434 Wetting Induced Collapse Behavior of Loosely Compacted Kaolin Soil: A Microstructural Study

Authors: Dhanesh Sing Das, Bharat Tadikonda Venkata

Abstract:

Collapsible soils undergo significant volume reduction upon wetting under the pre-existing mechanically applied normal stress (inundation pressure). These soils exhibit a very high strength in air-dried conditions and can carry up to a considerable magnitude of normal stress without undergoing significant volume change. The soil strength is, however, lost upon saturation and results in a sudden collapse of the soil structure under the existing mechanical stress condition. The intrusion of water into the dry deposits of such soil causes ground subsidence leading to damages in the overlying buildings/structures. A study on the wetting-induced volume change behavior of collapsible soils is essential in dealing with the ground subsidence problems in various geotechnical engineering practices. The collapse of loosely compacted Kaolin soil upon wetting under various inundation pressures has been reported in recent studies. The collapse in the Kaolin soil is attributed to the alteration in the soil particle-particle association (fabric) resulting due to the changes in the various inter-particle (microscale) forces induced by the water saturation. The inundation pressure plays a significant role in the fabric evolution during the wetting process, thus controls the collapse potential of the compacted soil. A microstructural study is useful to understand the collapse mechanisms at various pore-fabric levels under different inundation pressure. Kaolin soil compacted to a dry density of 1.25 g/cc was used in this work to study the wetting-induced volume change behavior under different inundation pressures in the range of 10-1600 kPa. The compacted specimen of Kaolin soil exhibited a consistent collapse under all the studied inundation pressure. The collapse potential was observed to be increasing with an increase in the inundation pressure up to a maximum value of 13.85% under 800 kPa and then decreased to 11.7% under 1600 kPa. Microstructural analysis was carried out based on the fabric images and the pore size distributions (PSDs) obtained from FESEM analysis and mercury intrusion porosimetry (MIP), respectively. The PSDs and the soil fabric images of ‘as-compacted’ specimen and post-collapse specimen under 400 kPa were analyzed to understand the changes in the soil fabric and pores due to wetting. The pore size density curve for the post-collapse specimen was found to be on the finer side with respect to the ‘as-compacted’ specimen, indicating the reduction of the larger pores during the collapse. The inter-aggregate pores in the range of 0.1-0.5μm were identified as the major contributing pore size classes to the macroscopic volume change. Wetting under an inundation pressure results in the reduction of these pore sizes and lead to an increase in the finer pore sizes. The magnitude of inundation pressure influences the amount of reduction of these pores during the wetting process. The collapse potential was directly related to the degree of reduction in the pore volume contributed by these pore sizes.

Keywords: collapse behavior, inundation pressure, kaolin, microstructure

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2433 Far-Field Noise Prediction of Tandem Cylinders Using Incompressible Large Eddy Simulation

Authors: Jesus Ruano, Francesc Xavier Trias, Asensi Oliva

Abstract:

A three-dimensional incompressible Large Eddy Simulation (LES) is performed to compute the hydrodynamic field around a pair of tandem cylinders. Symmetry-preserving schemes will be used during this simulation in conjunction with Finite Volume Method (FVM) to obtain the hydrodynamic field around the selected geometry. A set of results consisting of pressure and velocity and the combination of them will be stored at different surfaces near the cylinders as the initial input for the second part of the study. A post-processing of the obtained results based on Ffowcs-Williams and Hawkings (FWH) equation with a Fourier Transform of the acoustic sources will be used to compute noise at several probes located far away from the region where the hydrodynamics are computed. Directivities as well as spectral profile of the obtained acoustic field will be analyzed.

Keywords: far-field noise, Ffowcs-Williams and Hawkings, finite volume method, large eddy simulation, long-span bodies

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2432 Evaluating Residual Mechanical and Physical Properties of Concrete at Elevated Temperatures

Authors: S. Hachemi, A. Ounis, S. Chabi

Abstract:

This paper presents the results of an experimental study on the effects of elevated temperature on compressive and flexural strength of Normal Strength Concrete (NSC), High Strength Concrete (HSC) and High Performance Concrete (HPC). In addition, the specimen mass and volume were measured before and after heating in order to determine the loss of mass and volume during the test. In terms of non-destructive measurement, ultrasonic pulse velocity test was proposed as a promising initial inspection method for fire damaged concrete structure. 100 Cube specimens for three grades of concrete were prepared and heated at a rate of 3°C/min up to different temperatures (150, 250, 400, 600, and 900°C). The results show a loss of compressive and flexural strength for all the concretes heated to temperature exceeding 400°C. The results also revealed that mass and density of the specimen significantly reduced with an increase in temperature.

Keywords: high temperature, compressive strength, mass loss, ultrasonic pulse velocity

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2431 Prediction of Solidification Behavior of Al Alloy in a Cube Mold Cavity

Authors: N. P. Yadav, Deepti Verma

Abstract:

This paper focuses on the mathematical modeling for solidification of Al alloy in a cube mould cavity to study the solidification behavior of casting process. The parametric investigation of solidification process inside the cavity was performed by using computational solidification/melting model coupled with Volume of fluid (VOF) model. The implicit filling algorithm is used in this study to understand the overall process from the filling stage to solidification in a model metal casting process. The model is validated with past studied at same conditions. The solidification process are analyzed by including the effect of pouring velocity and temperature of liquid metal, effect of wall temperature as well natural convection from the wall and geometry of the cavity. These studies show the possibility of various defects during solidification process.

Keywords: buoyancy driven flow, natural convection driven flow, residual flow, secondary flow, volume of fluid

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2430 An Approach to Study the Biodegradation of Low Density Polyethylene Using Microbial Strains of Bacillus subtilus, Aspergillus niger, Pseudomonas fluroscence in Different Media Form and Salt Condition

Authors: Monu Ojha, Rahul Rana, Satywati Sharma, Kavya Dashora

Abstract:

The global production rate of plastics has increased enormously and global demand for polyethylene resins –High-density polyethylene (HDPE), Linear low-density polyethylene (LLDPE) and Low-density polyethylene (LDPE) is expected to rise drastically, with very high value. These get accumulated in the environment, posing a potential ecological threat as they are degrading at a very slow rate and remain in the environment indefinitely. The aim of the present study was to investigate the potential of commonly found soil microbes like Bacillus subtilus, Aspergillus niger, Pseudomonas fluroscence for their ability to biodegrade LDPE in the lab on solid and liquid media conditions as well as in presence of 1% salt in the soil. This study was conducted at Indian Institute of Technology, Delhi, India from July to September where average temperature and RH (Relative Humidity) were 33 degrees Celcius and 80% respectively. It revealed that the weight loss of LDPE strip obtained from market of approximately 4x6 cm dimensions is more in liquid broth media than in solid agar media. The percentage weight loss by P. fluroscence, A. niger and B. subtilus observed after 80 days of incubation was 15.52, 9.24 and 8.99% respectively in broth media and 6.93, 2.18 and 4.76 % in agar media. The LDPE strips from same source and on the same were subjected to soil in presence of above microbes with 1% salt (NaCl: obtained from commercial table salt) with temperature and RH 33 degree Celcius and 80%. It was found that the rate of degradation increased in the soil than under lab conditions. The rate of weight loss of LDPE strips under same conditions given in lab was found to be 32.98, 15.01 and17.09 % by P. fluroscence, A. niger and B. subtilus respectively. The breaking strength was found to be 9.65N, 29N and 23.85 N for P. fluroscence, A. niger and B. subtilus respectively. SEM analysis conducted on Zeiss EVO 50 confirmed that surface of LDPE becomes physically weak after biological treatment. There was the increase in the surface roughness indicating Surface erosion of LDPE film. FTIR (Fourier-transform infrared spectroscopy) analysis of the degraded LDPE films showed stretching of aldehyde group at 3334.92 and 3228.84 cm-1,, C–C=C symmetric of aromatic ring at 1639.49 cm-1.There was also C=O stretching of aldehyde group at 1735.93 cm-1. N=O peak bend was also observed which corresponds to 1365.60 cm-1, C–O stretching of ether group at 1217.08 and 1078.21 cm-1.

Keywords: microbial degradation, LDPE, Aspergillus niger, Bacillus subtilus, Peudomonas fluroscence, common salt

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2429 Using the Micro Computed Tomography to Study the Corrosion Behavior of Magnesium Alloy at Different pH Values

Authors: Chia-Jung Chang, Sheng-Che Chen, Ming-Long Yeh, Chih-Wei Wang, Chih-Han Chang

Abstract:

Introduction and Motivation: In recent years, magnesium alloy is used to be a kind of medical biodegradable materials. Magnesium is an essential element in the body and is efficiently excreted by the kidneys. Furthermore, the mechanical properties of magnesium alloy is closest to human bone. However, in some cases magnesium alloy corrodes so quickly that it would release hydrogen on surface of implant. The other product is hydroxide ion, it can significantly increase the local pH value. The above situations may have adverse effects on local cell functions. On the other hand, nowadays magnesium alloy corrode too fast to maintain the function of implant until the healing of tissue. Therefore, much recent research about magnesium alloy has focused on controlling the corrosion rate. The in vitro corrosion behavior of magnesium alloys is affected by many factors, and pH value is one of factors. In this study, we will study on the influence of pH value on the corrosion behavior of magnesium alloy by the Micro-CT (micro computed tomography) and other instruments.Material and methods: In the first step, we make some guiding plates for specimens of magnesium alloy AZ91 by Rapid Prototyping. The guiding plates are able to be a standard for the degradation of specimen, so that we can use it to make sure the position of specimens in the CT image. We can also simplify the conditions of degradation by the guiding plates.In the next step, we prepare the solution with different pH value. And then we put the specimens into the solution to start the corrosion test. The CT image, surface photographs and weigh are measured on every twelve hours. Results: In the primary results of the test, we make sure that CT image can be a way to quantify the corrosion behavior of magnesium alloy. Moreover we can observe the phenomenon that corrosion always start from some erosion point. It’s possibly based on some defect like dislocations and the voids with high strain energy in the materials. We will deal with the raw data into Mass Loss (ML) and corrosion rate by CT image, surface photographs and weigh in the near future. Having a simple prediction, the pH value and degradation rate will be negatively correlated. And we want to find out the equation of the pH value and corrosion rate. We also have a simple test to simulate the change of the pH value in the local region. In this test the pH value will rise to 10 in a short time. Conclusion: As a biodegradable implant for the area with stagnating body fluid flow in the human body, magnesium alloy can cause the increase of local pH values and release the hydrogen. Those may damage the human cell. The purpose of this study is finding out the equation of the pH value and corrosion rate. After that we will try to find the ways to overcome the limitations of medical magnesium alloy.

Keywords: magnesium alloy, biodegradable materials, corrosion, micro-CT

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2428 Extraction of Natural Colorant from the Flowers of Flame of Forest Using Ultrasound

Authors: Sunny Arora, Meghal A. Desai

Abstract:

An impetus towards green consumerism and implementation of sustainable techniques, consumption of natural products and utilization of environment friendly techniques have gained accelerated acceptance. Butein, a natural colorant, has many medicinal properties apart from its use in dyeing industries. Extraction of butein from the flowers of flame of forest was carried out using ultrasonication bath. Solid loading (2-6 g), extraction time (30-50 min), volume of solvent (30-50 mL) and types of solvent (methanol, ethanol and water) have been studied to maximize the yield of butein using the Taguchi method. The highest yield of butein 4.67% (w/w) was obtained using 4 g of plant material, 40 min of extraction time and 30 mL volume of methanol as a solvent. The present method provided a greater reduction in extraction time compared to the conventional method of extraction. Hence, the outcome of the present investigation could further be utilized to develop the method at a higher scale.

Keywords: butein, flowers of Flame of the Forest, Taguchi method, ultrasonic bath

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2427 Magneto-Hydrodynamic Mixed Convection of Water-Al2O3 Nanofluid in a Wavy Lid-Driven Cavity

Authors: Farshid Fathinia

Abstract:

This paper examines numerically the laminar steady magneto-hydrodynamic mixed convection flow and heat transfer in a wavy lid-driven cavity filled with water-Al2O3 nanofluid using FDM method. The left and right sidewalls of the cavity have a wavy geometry and are maintained at a cold and hot temperature, respectively. The top and bottom walls are considered flat and insulated while, the bottom wall moves from left to right direction with a uniform lid-driven velocity. A magnetic field is applied vertically downward on the bottom wall of the cavity. Based on the numerical results, the effects of the dominant parameters such as Rayleigh number, Hartmann number, solid volume fraction, and wavy wall geometry parameters are examined. The numerical results are obtained for Hartmann number varying as 0 ≤ Ha ≤ 0.6, Rayleigh numbers varying as 103≤ Ra ≤105, and the solid volume fractions varying as 0 ≤ φ ≤ 0.0003. Comparisons with previously published numerical works on mixed convection in a nanofluid filled cavity are performed and good agreements between the results are observed. It is found that the flow circulation and mean Nusselt number decrease as the solid volume fraction and Hartmann number increase. Moreover, the convection enhances when the amplitude ratio of the wavy surface increases. The results also show that both the flow and thermal fields are significantly affected by the amplitude ratio (i.e., wave form) of the wavy wall.

Keywords: nanofluid, mixed convection, magnetic field, wavy cavity, lid-driven, SPH method

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2426 Study on Reusable, Non Adhesive Silicone Male External Catheter: Clinical Proof of Study and Quality Improvement Project

Authors: Venkata Buddharaju, Irene Mccarron, Hazel Alba

Abstract:

Introduction: Male external catheters (MECs) are commonly used to collect and drain urine. MECs are increasingly used in acute care, long-term acute care hospitals, and nursing facilities, and in other patients as an alternative to invasive urinary catheters to reduce catheter-associated urinary tract infections (CAUTI).MECs are also used to avoid the need for incontinence pads and diapers. Most of the Male External Catheters are held in place by skin adhesive, with the exception of a few, which uses a foam strap clamp around the penile shaft. The adhesive condom catheters typically stay for 24 hours or less. It is also a common practice that extra skin adhesive tape is wrapped around the condom catheter for additional security of the device. The fixed nature of the adhesive will not allow the normal skin expansion of penile size over time. The adhesive can cause skin irritation, redness, erosion, and skin damage. Acanthus condom catheter (ACC) is a patented, specially designed, stretchable silicone catheter without adhesive, adapts to the size and contour of the penis. It is held in place with a single elastic strap that wraps around the lower back and tied to the opposite catheter ring holescriss cross. It can be reused for up to 5 days on the same patient after daily cleaning and washingpotentially reducing cost. Methods: The study was conducted from September 17th to October 8th, 2020. The nursing staff was educated and trained on how to use and reuse the catheter. After identifying five (5) appropriate patients, the catheter was placed and maintained by nursing staff. The data on the ease of use, leak, and skin damage were collected and reported by nurses to the nursing education department of the hospital for analysis. Setting: RML Chicago, long-term acute care hospital, an affiliate of Loyola University Medical Center, Chicago, IL USA. Results: The data showed that the catheter was easy to apply, remove, wash and reuse, without skin problems or urine infections. One patient had used for 16 days after wash, reuse, and replacement without any urine leak or skin issues. A minimal leak was observed on two patients. Conclusion: Acanthus condom catheter was easy to use, functioned well with minimal or no leak during use and reuse. The skin was intact in all patients studied. There were no urinary tract infections in any of the studied patients.

Keywords: CAUTI, male external catheter, reusable, skin adhesive

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2425 Effect of Bi-Dispersity on Particle Clustering in Sedimentation

Authors: Ali Abbas Zaidi

Abstract:

In free settling or sedimentation, particles form clusters at high Reynolds number and dilute suspensions. It is due to the entrapment of particles in the wakes of upstream particles. In this paper, the effect of bi-dispersity of settling particles on particle clustering is investigated using particle-resolved direct numerical simulation. Immersed boundary method is used for particle fluid interactions and discrete element method is used for particle-particle interactions. The solid volume fraction used in the simulation is 1% and the Reynolds number based on Sauter mean diameter is 350. Both solid volume fraction and Reynolds number lie in the clustering regime of sedimentation. In simulations, the particle diameter ratio (i.e. diameter of larger particle to smaller particle (d₁/d₂)) is varied from 2:1, 3:1 and 4:1. For each case of particle diameter ratio, solid volume fraction for each particle size (φ₁/φ₂) is varied from 1:1, 1:2 and 2:1. For comparison, simulations are also performed for monodisperse particles. For studying particles clustering, radial distribution function and instantaneous location of particles in the computational domain are studied. It is observed that the degree of particle clustering decreases with the increase in the bi-dispersity of settling particles. The smallest degree of particle clustering or dispersion of particles is observed for particles with d₁/d₂ equal to 4:1 and φ₁/φ₂ equal to 1:2. Simulations showed that the reduction in particle clustering by increasing bi-dispersity is due to the difference in settling velocity of particles. Particles with larger size settle faster and knockout the smaller particles from clustered regions of particles in the computational domain.

Keywords: dispersion in bi-disperse settling particles, particle microstructures in bi-disperse suspensions, particle resolved direct numerical simulations, settling of bi-disperse particles

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2424 Investigation of Heat Transfer of Nanofluids in Circular Microchannels

Authors: Bayram Sahin, Hourieh Bayramian, Emre Mandev, Murat Ceylan

Abstract:

In industrial applications, the demand for the enhancement of heat transfer is a common engineering problem. The use of additives to heat transfer fluid is a technique applied to enhance the heat transfer performance of base fluids. In this study, the thermal performance of nanofluids consisting of SiO2 particles and deionized water in circular microchannels was investigated experimentally. SiO2 nanoparticles with diameter of 15 nm were added to water to prepare nanofluids with 0.2% and 0.4% volume fractions. Heat transfer characteristics were calculated by using temperature, flow and pressure measurements. The thermal conductivity and viscosity values required for the calculations are measured separately. It is observed that the Nusselt number increases at the all volume fraction of particles, by increasing the Reynolds number and the volumetric ratios of the particles. The highest heat transfer enhancement is obtained at Re = 2160 and 0.4 % vol. by 14% under the condition of a constant pumping power.

Keywords: nanofluid, microchannel, heat transfer, SiO2-water nanofluid

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2423 Learning in Multicultural Workspaces: A Case of Aged Care

Authors: Robert John Godby

Abstract:

To be responsive now and in the future, workplaces must address the demands of multicultural teams as they become more common elements of the global labor force. This is especially the case for aged care due to the aging population, industry growth and migrant recruitment. This research identifies influences on and improvements for learning in these environments. Its unique contribution is to illuminate how culturally diverse workplaces can work and learn together more effectively. A mixed-methods approach was used to gather data about this topic in two phases. Firstly, the research methods included a survey of 102 aged care workers around Australia from two multi-site aged care organisations. The questionnaire elicited both quantitative and qualitative data about worker characteristics and perspectives on working and learning in aged care. Secondly, a case study of one aged care worksite was formulated drawing on worksite information and interviews with workers. A review of the literature suggests that learning in multicultural work environments is influenced by three main factors: 1) the individual workers themselves, 2) their interaction with each other and 3) the environment in which they work. There are various accounts of these three factors, how they are manifested and how they lead to a change in workers’ disposition, knowledge, or expertise when confronted with new circumstances. The study has found that a key individual factor influencing learning is cultural background. Their unique view of the world was shown to affect their approach to both their work and co-working. Interactional factors suggest that the high requirement for collaboration in aged care positively supports learning in this context; however, it can be hindered by cultural bias and spoken accent. The study also found that environmental factors, such as disruptions caused by the pandemic, were another key influence. For example, the need to wear face masks hindered the communication needed for workplace learning. This was especially challenging due to the diverse language backgrounds and abilities within the teams. Potential improvements for learning in multicultural aged care work environments were identified. These include more frequent and structured inter-peer learning (e.g. buddying), communication training (e.g. English language usage for both native and non-native speaking workers) and support for cross-cultural habitude (e.g. recognizing and adapting to cultural differences). Workplace learning in cross-cultural aged care environments is an area that is not extensively dealt with in the literature. This study addresses this gap and holds the potential to contribute practical insights to aged care and other diverse industries.

Keywords: cross-cultural learning, learning in aged care, migrant learning, workplace learning

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2422 Evaluation of Heat Transfer and Entropy Generation by Al2O3-Water Nanofluid

Authors: Houda Jalali, Hassan Abbassi

Abstract:

In this numerical work, natural convection and entropy generation of Al2O3–water nanofluid in square cavity have been studied. A two-dimensional steady laminar natural convection in a differentially heated square cavity of length L, filled with a nanofluid is investigated numerically. The horizontal walls are considered adiabatic. Vertical walls corresponding to x=0 and x=L are respectively maintained at hot temperature, Th and cold temperature, Tc. The resolution is performed by the CFD code "FLUENT" in combination with GAMBIT as mesh generator. These simulations are performed by maintaining the Rayleigh numbers varied as 103 ≤ Ra ≤ 106, while the solid volume fraction varied from 1% to 5%, the particle size is fixed at dp=33 nm and a range of the temperature from 20 to 70 °C. We used models of thermophysical nanofluids properties based on experimental measurements for studying the effect of adding solid particle into water in natural convection heat transfer and entropy generation of nanofluid. Such as models of thermal conductivity and dynamic viscosity which are dependent on solid volume fraction, particle size and temperature. The average Nusselt number is calculated at the hot wall of the cavity in a different solid volume fraction. The most important results is that at low temperatures (less than 40 °C), the addition of nanosolids Al2O3 into water leads to a decrease in heat transfer and entropy generation instead of the expected increase, whereas at high temperature, heat transfer and entropy generation increase with the addition of nanosolids. This behavior is due to the contradictory effects of viscosity and thermal conductivity of the nanofluid. These effects are discussed in this work.

Keywords: entropy generation, heat transfer, nanofluid, natural convection

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2421 Using ICESat-2 Dynamic Ocean Topography to Estimate Western Arctic Freshwater Content

Authors: Joshua Adan Valdez, Shawn Gallaher

Abstract:

Global climate change has impacted atmospheric temperatures contributing to rising sea levels, decreasing sea ice, and increased freshening of high latitude oceans. This freshening has contributed to increased stratification inhibiting local mixing and nutrient transport, modifying regional circulations in polar oceans. In recent years, the Western Arctic has seen an increase in freshwater volume at an average rate of 397+-116km3/year across the Beaufort Gyre. The majority of the freshwater volume resides in the Beaufort Gyre surface lens driven by anticyclonic wind forcing, sea ice melt, and Arctic river runoff, and is typically defined as water fresher than 34.8. The near-isothermal nature of Arctic seawater and non-linearities in the equation of state for near-freezing waters result in a salinity-driven pycnocline as opposed to the temperature-driven density structure seen in the lower latitudes. In this study, we investigate the relationship between freshwater content and dynamic ocean topography (DOT). In situ measurements of freshwater content are useful in providing information on the freshening rate of the Beaufort Gyre; however, their collection is costly and time-consuming. Utilizing NASA’s ICESat-2’s DOT remote sensing capabilities and Air Expendable CTD (AXCTD) data from the Seasonal Ice Zone Reconnaissance Surveys (SIZRS), a linear regression model between DOT and freshwater content is determined along the 150° west meridian. Freshwater content is calculated by integrating the volume of water between the surface and a depth with a reference salinity of ~34.8. Using this model, we compare interannual variability in freshwater content within the gyre, which could provide a future predictive capability of freshwater volume changes in the Beaufort-Chukchi Sea using non-in situ methods. Successful employment of the ICESat-2’s DOT approximation of freshwater content could potentially demonstrate the value of remote sensing tools to reduce reliance on field deployment platforms to characterize physical ocean properties.

Keywords: Cryosphere, remote sensing, Arctic oceanography, climate modeling, Ekman transport

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2420 Investigating the Impacts on Cyclist Casualty Severity at Roundabouts: A UK Case Study

Authors: Nurten Akgun, Dilum Dissanayake, Neil Thorpe, Margaret C. Bell

Abstract:

Cycling has gained a great attention with comparable speeds, low cost, health benefits and reducing the impact on the environment. The main challenge associated with cycling is the provision of safety for the people choosing to cycle as their main means of transport. From the road safety point of view, cyclists are considered as vulnerable road users because they are at higher risk of serious casualty in the urban network but more specifically at roundabouts. This research addresses the development of an enhanced mathematical model by including a broad spectrum of casualty related variables. These variables were geometric design measures (approach number of lanes and entry path radius), speed limit, meteorological condition variables (light, weather, road surface) and socio-demographic characteristics (age and gender), as well as contributory factors. Contributory factors included driver’s behavior related variables such as failed to look properly, sudden braking, a vehicle passing too close to a cyclist, junction overshot, failed to judge other person’s path, restart moving off at the junction, poor turn or manoeuvre and disobeyed give-way. Tyne and Wear in the UK were selected as a case study area. The cyclist casualty data was obtained from UK STATS19 National dataset. The reference categories for the regression model were set to slight and serious cyclist casualties. Therefore, binary logistic regression was applied. Binary logistic regression analysis showed that approach number of lanes was statistically significant at the 95% level of confidence. A higher number of approach lanes increased the probability of severity of cyclist casualty occurrence. In addition, sudden braking statistically significantly increased the cyclist casualty severity at the 95% level of confidence. The result concluded that cyclist casualty severity was highly related to approach a number of lanes and sudden braking. Further research should be carried out an in-depth analysis to explore connectivity of sudden braking and approach number of lanes in order to investigate the driver’s behavior at approach locations. The output of this research will inform investment in measure to improve the safety of cyclists at roundabouts.

Keywords: binary logistic regression, casualty severity, cyclist safety, roundabout

Procedia PDF Downloads 177
2419 Study of Influencing Factors on the Flowability of Jute Nonwoven Reinforced Sheet Molding Compound

Authors: Miriam I. Lautenschläger, Max H. Scheiwe, Kay A. Weidenmann, Frank Henning, Peter Elsner

Abstract:

Due to increasing environmental awareness jute fibers are more often used in fiber reinforced composites. In the Sheet Molding Compound (SMC) process, the mold cavity is filled via material flow allowing more complex component design. But, the difficulty of using jute fibers in this process is the decreased capacity of fiber movement in the mold. A comparative flow study with jute nonwoven reinforced SMC was conducted examining the influence of the fiber volume content, the grammage of the jute nonwoven textile and a mechanical modification of the nonwoven textile on the flowability. The nonwoven textile reinforcement was selected to support homogeneous fiber distribution. Trials were performed using two SMC paste formulations differing only in filler type. Platy-shaped kaolin with a mean particle size of 0.8 μm and ashlar calcium carbonate with a mean particle size of 2.7 μm were selected as fillers. Ensuring comparability of the two SMC paste formulations the filler content was determined to reach equal initial viscosity for both systems. The calcium carbonate filled paste was set as reference. The flow study was conducted using a jute nonwoven textile with 300 g/m² as reference. The manufactured SMC sheets were stacked and centrally placed in a square mold. The mold coverage was varied between 25 and 90% keeping the weight of the stack for comparison constant. Comparing the influence of the two fillers kaolin yielded better results regarding a homogeneous fiber distribution. A mold coverage of about 68% was already sufficient to homogeneously fill the mold cavity whereas for calcium carbonate filled system about 79% mold coverage was necessary. The flow study revealed a strong influence of the fiber volume content on the flowability. A fiber volume content of 12 vol.-% and 25 vol.-% were compared for both SMC formulations. The lower fiber volume content strongly supported fiber transport whereas 25 vol.-% showed insignificant influence. The results indicate a limiting fiber volume content for the flowability. The influence of the nonwoven textile grammage was determined using nonwoven jute material with 500 g/m² and a fiber volume content of 20 vol.-%. The 500 g/m² reinforcement material showed inferior results with regard to fiber movement. A mold coverage of about 90 % was required to prevent the destruction of the nonwoven structure. Below this mold coverage the 500 g/m² nonwoven material was ripped and torn apart. Low mold coverages led to damage of the textile reinforcement. Due to the ripped nonwoven structure the textile was modified with cuts in order to facilitate fiber movement in the mold. Parallel cuts of about 20 mm length and 20 mm distance to each other were applied to the textile and stacked with varying orientations prior to molding. Stacks with unidirectional orientated cuts over stacks with cuts in various directions e.g. (0°, 45°, 90°, -45°) were investigated. The mechanical modification supported tearing of the textile without achieving benefit for the flowability.

Keywords: filler, flowability, jute fiber, nonwoven, sheet molding compound

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2418 Development of a New Piezoelectrically Actuated Micropump for Liquid and Gas

Authors: Chiang-Ho Cheng, An-Shik Yang, Chih-Jer Lin, Chun-Ying Lee

Abstract:

This paper aims to present the design, fabrication and test of a novel piezoelectric actuated, check-valves embedded micropump having the advantages of miniature size, light weight and low power consumption. This device is designed to pump gases and liquids with the capability of performing the self-priming and bubble-tolerant work mode by maximizing the stroke volume of the membrane as well as the compression ratio via minimization of the dead volume of the micropump chamber and channel. By experiment apparatus setup, we can get the real-time values of the flow rate of micropump, the displacement of the piezoelectric actuator and the deformation of the check valve, simultaneously. The micropump with check valve 0.4 mm in thickness obtained higher output performance under the sinusoidal waveform of 120 Vpp. The micropump achieved the maximum pumping rates of 42.2 ml/min and back pressure of 14.0 kPa at the corresponding frequency of 28 and 20 Hz. The presented micropump is able to pump gases with a pumping rate of 196 ml/min at operating frequencies of 280 Hz under the sinusoidal waveform of 120 Vpp.

Keywords: actuator, check-valve, micropump, piezoelectric

Procedia PDF Downloads 432
2417 Treatment and Diagnostic Imaging Methods of Fetal Heart Function in Radiology

Authors: Mahdi Farajzadeh Ajirlou

Abstract:

Prior evidence of normal cardiac anatomy is desirable to relieve the anxiety of cases with a family history of congenital heart disease or to offer the option of early gestation termination or close follow-up should a cardiac anomaly be proved. Fetal heart discovery plays an important part in the opinion of the fetus, and it can reflect the fetal heart function of the fetus, which is regulated by the central nervous system. Acquisition of ventricular volume and inflow data would be useful to quantify more valve regurgitation and ventricular function to determine the degree of cardiovascular concession in fetal conditions at threat for hydrops fetalis. This study discusses imaging the fetal heart with transvaginal ultrasound, Doppler ultrasound, three-dimensional ultrasound (3DUS) and four-dimensional (4D) ultrasound, spatiotemporal image correlation (STIC), glamorous resonance imaging and cardiac catheterization. Doppler ultrasound (DUS) image is a kind of real- time image with a better imaging effect on blood vessels and soft tissues. DUS imaging can observe the shape of the fetus, but it cannot show whether the fetus is hypoxic or distressed. Spatiotemporal image correlation (STIC) enables the acquisition of a volume of data concomitant with the beating heart. The automated volume accession is made possible by the array in the transducer performing a slow single reach, recording a single 3D data set conforming to numerous 2D frames one behind the other. The volume accession can be done in a stationary 3D, either online 4D (direct volume scan, live 3D ultrasound or a so-called 4D (3D/ 4D)), or either spatiotemporal image correlation-STIC (off-line 4D, which is a circular volume check-up). Fetal cardiovascular MRI would appear to be an ideal approach to the noninvasive disquisition of the impact of abnormal cardiovascular hemodynamics on antenatal brain growth and development. Still, there are practical limitations to the use of conventional MRI for fetal cardiovascular assessment, including the small size and high heart rate of the mortal fetus, the lack of conventional cardiac gating styles to attend data accession, and the implicit corruption of MRI data due to motherly respiration and unpredictable fetal movements. Fetal cardiac MRI has the implicit to complement ultrasound in detecting cardiovascular deformations and extracardiac lesions. Fetal cardiac intervention (FCI), minimally invasive catheter interventions, is a new and evolving fashion that allows for in-utero treatment of a subset of severe forms of congenital heart deficiency. In special cases, it may be possible to modify the natural history of congenital heart disorders. It's entirely possible that future generations will ‘repair’ congenital heart deficiency in utero using nanotechnologies or remote computer-guided micro-robots that work in the cellular layer.

Keywords: fetal, cardiac MRI, ultrasound, 3D, 4D, heart disease, invasive, noninvasive, catheter

Procedia PDF Downloads 39
2416 Working From Home: On the Relationship Between Place Attachment to Work Place, Extraversion and Segmentation Preference to Burnout

Authors: Diamant Irene, Shklarnik Batya

Abstract:

In on to its widespread effects on health and economic issues, Covid-19 shook the work and employment world. Among the prominent changes during the pandemic is the work-from-home trend, complete or partial, as part of social distancing. In fact, these changes accelerated an existing tendency of work flexibility already underway before the pandemic. Technology and means of advanced communications led to a re-assessment of “place of work” as a physical space in which work takes place. Today workers can remotely carry out meetings, manage projects, work in groups, and different research studies point to the fact that this type of work has no adverse effect on productivity. However, from the worker’s perspective, despite numerous advantages associated with work from home, such as convenience, flexibility, and autonomy, various drawbacks have been identified such as loneliness, reduction of commitment, home-work boundary erosion, all risk factors relating to the quality of life and burnout. Thus, a real need has arisen in exploring differences in work-from-home experiences and understanding the relationship between psychological characteristics and the prevalence of burnout. This understanding may be of significant value to organizations considering a future hybrid work model combining in-office and remote working. Based on Hobfoll’s Theory of Conservation of Resources, we hypothesized that burnout would mainly be found among workers whose physical remoteness from the workplace threatens or hinders their ability to retain significant individual resources. In the present study, we compared fully remote and partially remote workers (hybrid work), and we examined psychological characteristics and their connection to the formation of burnout. Based on the conceptualization of Place Attachment as the cognitive-emotional bond of an individual to a meaningful place and the need to maintain closeness to it, we assumed that individuals characterized with Place Attachment to the workplace would suffer more from burnout when working from home. We also assumed that extrovert individuals, characterized by the need of social interaction at the workplace and individuals with segmentationpreference – a need for separation between different life domains, would suffer more from burnout, especially among fully remote workers relative to partially remote workers. 194 workers, of which 111 worked from home in full and 83 worked partially from home, aged 19-53, from different sectors, were tested using an online questionnaire through social media. The results of the study supported our assumptions. The repercussions of these findings are discussed, relating to future occupational experience, with an emphasis on suitable occupational adjustment according to the psychological characteristics and needs of workers.

Keywords: working from home, burnout, place attachment, extraversion, segmentation preference, Covid-19

Procedia PDF Downloads 190
2415 Effect of Carbide Precipitates in Tool Steel on Material Transfer: A Molecular Dynamics Study

Authors: Ahmed Tamer AlMotasem, Jens Bergström, Anders Gåård, Pavel Krakhmalev, Thijs Jan Holleboom

Abstract:

In sheet metal forming processes, accumulation and transfer of sheet material to tool surfaces, often referred to as galling, is the major cause of tool failure. Initiation of galling is assumed to occur due to local adhesive wear between two surfaces. Therefore, reducing adhesion between the tool and the work sheet has a great potential to improve the tool materials galling resistance. Experimental observations and theoretical studies show that the presence of primary micro-sized carbides and/or nitrides in alloyed steels may significantly improve galling resistance. Generally, decreased adhesion between the ceramic precipitates and the sheet material counter-surface are attributed as main reason to the latter observations. On the other hand, adhesion processes occur at an atomic scale and, hence, fundamental understanding of galling can be obtained via atomic scale simulations. In the present study, molecular dynamics simulations are used, with utilizing second nearest neighbor embedded atom method potential to investigate the influence of nano-sized cementite precipitates embedded in tool atoms. The main aim of the simulations is to gain new fundamental knowledge on galling initiation mechanisms. Two tool/work piece configurations, iron/iron and iron-cementite/iron, are studied under dry sliding conditions. We find that the average frictional force decreases whereas the normal force increases for the iron-cementite/iron system, in comparison to the iron/iron configuration. Moreover, the average friction coefficient between the tool/work-piece decreases by about 10 % for the iron-cementite/iron case. The increase of the normal force in the case of iron-cementite/iron system may be attributed to the high stiffness of cementite compared to bcc iron. In order to qualitatively explain the effect of cementite on adhesion, the adhesion force between self-mated iron/iron and cementite/iron surfaces has been determined and we found that iron/cementite surface exhibits lower adhesive force than that of iron-iron surface. The variation of adhesion force with temperature was investigated up to 600 K and we found that the adhesive force, generally, decreases with increasing temperature. Structural analyses show that plastic deformation is the main deformation mechanism of the work-piece, accompanied with dislocations generation.

Keywords: adhesion, cementite, galling, molecular dynamics

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2414 Fragile Mires as Living Heritage: Human-Nature Relations in Contemporary Digital Life

Authors: Kirsi Laurén, Tiina Seppä

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This study focuses on human-mire relations in the context of digital aestheticization and the long-standing tradition of folklore concerning mires. The study concentrates on the Patvinsuo mire in Eastern Finland and the Viiankiaapa mire in Finnish Lapland. Patvinsuo is a national park, and Viiankiaapa is a protected mire area with hiking trails and other recreational infrastructure. Perceiving the environment through digital technology can help to notice aesthetic details in nature. In addition, sharing images and texts digitally through social media adds a sense of community to the relationship with nature and, at the same time, creates a different kind of living heritage where old and new traditions meet and mingle. People visiting and camping in these areas 'self-care' themselves through recreation in nature. However, these practices and digital aestheticization can sometimes lead to the erosion of fragile mires. The research focuses on understanding the impact of digital aestheticization, such as taking digital photos, on the relationship with nature for individuals moving and working in mires. Additionally, the study aims to explore the contemporary perception of the water environment in mires and its cultural heritage, including mythical and folkloric elements. The research material consists of senso-digital walking interviews and digital recordings (audio recordings, photographs, videos) made during the mire walks, as well as archival material from the Finnish Literature Society’s Archives on mire folklore. The analysis of the material relies centrally on theories from sensory anthropology on the relationship between sensory perception and culture. The modern-day interviewees include outdoor enthusiasts spending their leisure time in mires, artists treating mires in their art, and nature experts (scientists, civil servants, and nature guides). The senso-digital walking interviews were conducted in Patvinsuo and Viiankiaapa mires on a trail chosen by the interviewees themselves. The material selected from the archive consists mainly of folk beliefs and folk poetry from the 19th and 20th centuries that express the relationship of the narrator to the mires. The interview and archival materials date from different periods and are different in character, which has to be taken into account in the analysis. However, in the analysis of both materials, particular attention is paid to the descriptions of sensations that appear in them. Analyzing the materials in parallel is limited by the fact that they date from different periods, but on the other hand, it is their different ages that make it possible to perceive the changes in the cultural heritage of mires.

Keywords: mires, living heritage, digital aestheticization, folklore, sensory anthropology

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2413 Effect of Tooth Bleaching Agents on Enamel Demineralisation

Authors: Najlaa Yousef Qusti, Steven J. Brookes, Paul A. Brunton

Abstract:

Background: Tooth discoloration can be an aesthetic problem, and tooth whitening using carbamide peroxide bleaching agents are a popular treatment option. However, there are concerns about possible adverse effects such as demineralisation of the bleached enamel; however, the cause of this demineralisation is unclear. Introduction: Teeth can become stained or discoloured over time. Tooth whitening is an aesthetic solution for tooth discoloration. Bleaching solutions of 10% carbamide peroxide (CP) have become the standard agent used in dentist-prescribed and home-applied ’vital bleaching techniques’. These materials release hydrogen peroxide (H₂O₂), the active whitening agent. However, there is controversy in the literature regarding the effect of bleaching agents on enamel integrity and enamel mineral content. The purpose of this study was to establish if carbamide peroxide bleaching agents affect the acid solubility of enamel (i.e., make teeth more prone to demineralisation). Materials and Methods: Twelve human premolar teeth were sectioned longitudinally along the midline and varnished to leave the natural enamel surface exposed. The baseline behavior of each tooth half in relation to its demineralisation in acid was established by sequential exposure to 4 vials containing 1ml of 10mM acetic acid (1 minute/vial). This was followed by exposure to 10% CP for 8 hours. After washing in distilled water, the tooth half was sequentially exposed to 4 further vials containing acid to test if the acid susceptibility of the enamel had been affected. The corresponding tooth half acted as a control and was exposed to distilled water instead of CP. The mineral loss was determined by measuring [Ca²⁺] and [PO₄³⁻] released in each vial using a calcium ion-selective electrode and the phosphomolybdenum blue method, respectively. The effect of bleaching on the tooth surfaces was also examined using SEM. Results: Exposure to carbamide peroxide did not significantly alter the susceptibility of enamel to acid attack, and SEM of the enamel surface revealed a slight alteration in surface appearance. SEM images of the control enamel surface showed a flat enamel surface with some shallow pits, whereas the bleached enamel appeared with an increase in surface porosity and some areas of mild erosion. Conclusions: Exposure to H₂O₂ equivalent to 10% CP does not significantly increase subsequent acid susceptibility of enamel as determined by Ca²⁺ release from the enamel surface. The effects of bleaching on mineral loss were indistinguishable from distilled water in the experimental system used. However, some surface differences were observed by SEM. The phosphomolybdenum blue method for phosphate is compromised by peroxide bleaching agents due to their oxidising properties. However, the Ca²⁺ electrode is unaffected by oxidising agents and can be used to determine the mineral loss in the presence of peroxides.

Keywords: bleaching, carbamide peroxide, demineralisation, teeth whitening

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2412 Speed Characteristics of Mixed Traffic Flow on Urban Arterials

Authors: Ashish Dhamaniya, Satish Chandra

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Speed and traffic volume data are collected on different sections of four lane and six lane roads in three metropolitan cities in India. Speed data are analyzed to fit the statistical distribution to individual vehicle speed data and all vehicles speed data. It is noted that speed data of individual vehicle generally follows a normal distribution but speed data of all vehicle combined at a section of urban road may or may not follow the normal distribution depending upon the composition of traffic stream. A new term Speed Spread Ratio (SSR) is introduced in this paper which is the ratio of difference in 85th and 50th percentile speed to the difference in 50th and 15th percentile speed. If SSR is unity then speed data are truly normally distributed. It is noted that on six lane urban roads, speed data follow a normal distribution only when SSR is in the range of 0.86 – 1.11. The range of SSR is validated on four lane roads also.

Keywords: normal distribution, percentile speed, speed spread ratio, traffic volume

Procedia PDF Downloads 422
2411 Application of UAS in Forest Firefighting for Detecting Ignitions and 3D Fuel Volume Estimation

Authors: Artur Krukowski, Emmanouela Vogiatzaki

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The article presents results from the AF3 project “Advanced Forest Fire Fighting” focused on Unmanned Aircraft Systems (UAS)-based 3D surveillance and 3D area mapping using high-resolution photogrammetric methods from multispectral imaging, also taking advantage of the 3D scanning techniques from the SCAN4RECO project. We also present a proprietary embedded sensor system used for the detection of fire ignitions in the forest using near-infrared based scanner with weight and form factors allowing it to be easily deployed on standard commercial micro-UAVs, such as DJI Inspire or Mavic. Results from real-life pilot trials in Greece, Spain, and Israel demonstrated added-value in the use of UAS for precise and reliable detection of forest fires, as well as high-resolution 3D aerial modeling for accurate quantification of human resources and equipment required for firefighting.

Keywords: forest wildfires, surveillance, fuel volume estimation, firefighting, ignition detectors, 3D modelling, UAV

Procedia PDF Downloads 142