Search results for: biotic and abiotic stresses

Authors: Lukasz Grabowski, Marcin Szlachetka, Tytus Tulwin

Abstract:

The main task of the engine cooling system is to maintain its average operating temperatures within strictly defined limits. Too high or too low average temperatures result in accelerated wear or even damage to the engine or its individual components. In order to avoid local overheating or significant temperature gradients, leading to high stresses in the component, the aim is to ensure an even flow of air. In the case of analyses related to heat exchange, one of the main problems is the comparison of temperature fields because standard measuring instruments such as thermocouples or thermistors only provide information about the course of temperature at a given point. Thermal imaging tests can be helpful in this case. With appropriate camera settings and taking into account environmental conditions, we are able to obtain accurate temperature fields in the form of thermograms. Emission of heat from the engine to the engine compartment is an important issue when designing a cooling system. Also, in the case of liquid cooling, the main sources of heat in the form of emissions from the engine block, cylinders, etc. should be identified. It is important to redesign the engine compartment ventilation system. Ensuring proper cooling of aircraft reciprocating engine is difficult not only because of variable operating range but mainly because of different cooling conditions related to the change of speed or altitude of flight. Engine temperature also has a direct and significant impact on the properties of engine oil, which under the influence of this parameter changes, in particular, its viscosity. Too low or too high, its value can be a result of fast wear of engine parts. One of the ways to determine the temperatures occurring on individual parts of the engine is the use of thermal imaging measurements. The article presents the results of preliminary thermal imaging tests of aircraft piston diesel engine with a maximum power of about 100 HP. In order to perform the heat emission tests of the tested engine, the ThermaCAM S65 thermovision monitoring system from FLIR (Forward-Looking Infrared) together with the ThermaCAM Researcher Professional software was used. The measurements were carried out after the engine warm up. The engine speed was 5300 rpm The measurements were taken for the following environmental parameters: air temperature: 17 °C, ambient pressure: 1004 hPa, relative humidity: 38%. The temperatures distribution on the engine cylinder and on the exhaust manifold were analysed. Thermal imaging tests made it possible to relate the results of simulation tests to the real object by measuring the rib temperature of the cylinders. The results obtained are necessary to develop a CFD (Computational Fluid Dynamics) model of heat emission from the engine bay. The project/research was financed in the framework of the project Lublin University of Technology-Regional Excellence Initiative, funded by the Polish Ministry of Science and Higher Education (contract no. 030/RID/2018/19).

Keywords: aircraft, piston engine, heat, emission

Procedia PDF Downloads 96

Authors: Anderson Braga Mendes, Wallington Felipe de Almeida, Cicero Medeiros da Silva

Abstract:

This study aimed to assess the lifespan of the fish transposition system of the Itaipu Power Plant (Brazil/Paraguay) by using 3D hydrodynamic modeling and Churchill trapping effiency in order to identify the sedimentological equilibrium configuration in the main pond of the Piracema Channel, which is part of a 10 km hydraulic circuit that enables fish migration from downstream to upstream (and vice-versa) the Itaipu Dam, overcoming a 120 m water drop. For that, bottom data from 2002 (its opening year) and 2015 were collected and analyzed, besides bed material at 12 stations to the purpose of identifying their granulometric profiles. The Shields and Yalin and Karahan diagrams for initiation of motion of bed material were used to determine the critical bed shear stress for the sedimentological equilibrium state based on the sort of sediment (grain size) to be found at the bottom once the balance is reached. Such granulometry was inferred by analyzing the grosser material (fine and medium sands) which inflows the pond and deposits in its backwater zone, being adopted a range of diameters within the upper and lower limits of that sand stratification. The software Delft 3D was used in an attempt to compute the bed shear stress at every station under analysis. By modifying the input bathymetry of the main pond of the Piracema Channel so as to the computed bed shear stress at each station fell within the intervals of acceptable critical stresses simultaneously, it was possible to foresee the bed configuration of the main pond when the sedimentological equilibrium is reached. Under such condition, 97% of the whole pond capacity will be silted, and a shallow water course with depths ranging from 0.2 m to 1.5 m will be formed; in 2002, depths ranged from 2 m to 10 m. Out of that water path, the new bottom will be practically flat and covered by a layer of water 0.05 m thick. Thus, in the future the main pond of the Piracema Channel will lack its purpose of providing a resting place for migrating fish species, added to the fact that it may become an insurmountable barrier for medium and large sized specimens. Everything considered, it was estimated that its lifespan, from the year of its opening to the moment of the sedimentological equilibrium configuration, will be approximately 95 years–almost half of the computed lifespan of Itaipu Power Plant itself. However, it is worth mentioning that drawbacks concerning the silting in the main pond will start being noticed much earlier than such time interval owing to the reasons previously mentioned.

Keywords: 3D hydrodynamic modeling, Churchill trapping efficiency, fish crossing system, Itaipu power plant, lifespan, sedimentological equilibrium

Procedia PDF Downloads 210

Authors: Mohammad Afkhami, Ali Hassanpour, Michael Fairweather

Abstract:

The work described in this paper was undertaken to gain insight into fundamental aspects of turbulent gas-particle flows with relevance to processes employed in a wide range of applications, such as oil and gas flow assurance in pipes, powder dispersion from dry powder inhalers, and particle resuspension in nuclear waste ponds, to name but a few. In particular, the influence of particle interaction and fluid phase behavior in turbulent flow on particle dispersion in a horizontal channel is investigated. The mathematical modeling technique used is based on the large eddy simulation (LES) methodology embodied in the commercial CFD code FLUENT, with flow solutions provided by this approach coupled to a second commercial code, EDEM, based on the discrete element method (DEM) which is used for the prediction of particle motion and interaction. The results generated by LES for the fluid phase have been validated against direct numerical simulations (DNS) for three different channel flows with shear Reynolds numbers, Reτ = 150, 300 and 590. Overall, the LES shows good agreement, with mean velocities and normal and shear stresses matching those of the DNS in both magnitude and position. The research work has focused on the prediction of those conditions favoring particle aggregation and deposition within turbulent flows. Simulations have been carried out to investigate the effects of particle size, density and concentration on particle agglomeration. Furthermore, particles with different surface properties have been simulated in three channel flows with different levels of flow turbulence, achieved by increasing the Reynolds number of the flow. The simulations mimic the conditions of two-phase, fluid-solid flows frequently encountered in domestic, commercial and industrial applications, for example, air conditioning and refrigeration units, heat exchangers, oil and gas suction and pressure lines. The particle size, density, surface energy and volume fractions selected are 45.6, 102 and 150 µm, 250, 1000 and 2159 kg m-3, 50, 500, and 5000 mJ m-2 and 7.84 × 10-6, 2.8 × 10-5, and 1 × 10-4, respectively; such particle properties are associated with particles found in soil, as well as metals and oxides prevalent in turbulent bounded fluid-solid flows due to erosion and corrosion of inner pipe walls. It has been found that the turbulence structure of the flow dominates the motion of the particles, creating particle-particle interactions, with most of these interactions taking place at locations close to the channel walls and in regions of high turbulence where their agglomeration is aided both by the high levels of turbulence and the high concentration of particles. A positive relationship between particle surface energy, concentration, size and density, and agglomeration was observed. Moreover, the results derived for the three Reynolds numbers considered show that the rate of agglomeration is strongly influenced for high surface energy particles by, and increases with, the intensity of the flow turbulence. In contrast, for lower surface energy particles, the rate of agglomeration diminishes with an increase in flow turbulence intensity.

Keywords: agglomeration, channel flow, DEM, LES, turbulence

Procedia PDF Downloads 291

Authors: Douglas E. Mainhart, Alejandro Fierro-Cabo, Bradley Christoffersen, Charlotte Reemts

Abstract:

Semi-arid ecosystems across the globe have faced land conversion for agriculture and resource extraction activities, posing a threat to the important ecosystem services they provide. Revegetation-centered restoration efforts in these regions face low success rates due to limited soil water availability and high temperatures leading to elevated seedling mortality after planting. Typical methods to alleviate these stresses require costly post-planting interventions aimed at improving soil moisture status. We set out to evaluate the efficacy of applying in-nursery treatments to address transplant shock. Four native Tamaulipan thornscrub species were compared. Three treatments were applied: elevated CO2, drought hardening (four-week exposure each), and antitranspirant foliar spray (the day prior to planting). Our goal was to answer two primary questions: (1) Do treatments improve survival and growth of seedlings in the early period post-planting? (2) If so, what underlying physiological changes are associated with this improved performance? To this end, we measured leaf gas exchange (stomatal conductance, light saturated photosynthetic rate, water use efficiency), leaf morphology (specific leaf area), and osmolality before and upon the conclusion of treatments. A subset of seedlings from all treatments have been planted, which will be monitored in coming months for in-field survival and growth.First month field survival for all treatment groups were high due to ample rainfall following planting (>85%). Growth data was unreliable due to high herbivory (68% of all sampled plants). While elevated CO2 had infrequent or no detectable influence on all aspects of leaf gas exchange, drought hardening reduced stomatal conductance in three of the four species measured without negatively impacting photosynthesis. Both CO2 and drought hardening elevated leaf osmolality in two species. Antitranspirant application significantly reduced conductance in all species for up to four days and reduced photosynthesis in two species. Antitranspirants also increased the variability of water use efficiency compared to controls. Collectively, these results suggest that antitranspirants and drought hardening are viable treatments for reducing short-term water loss during the transplant shock period. Elevated CO2, while not effective at reducing water loss, may be useful for promoting more favorable water status via osmotic adjustment. These practices could improve restoration outcomes in Tamaulipan thornscrub and other semi-arid systems. Further research should focus on evaluating combinations of these treatments and their species-specific viability.

Keywords: conservation, drought conditioning, semi-arid restoration, plant physiology

Procedia PDF Downloads 60

Authors: Sanjeev Gupta, Ankit Prabhakar, K. Rajkumar Singh

Abstract:

Sunni Dam Hydroelectric Project (382 MW) is a run of river type development with an underground powerhouse, proposed to harness the hydel potential of river Satluj in Himachal Pradesh, India. The project is located in the inner lesser Himalaya between Dhauladhar Range in the south and the higher Himalaya in the north. The project comprises two large underground caverns, a Powerhouse cavern (171m long, 22.5m wide and 51.2m high) and another transformer hall cavern (175m long, 18.7m wide and 27m high) and the rock pillar between the two caverns is 50m. The highly jointed, fractured, anisotropic rock mass is a key challenge in Himalayan geology for an underground structure. The concern for the stability of rock mass increases when weak/shear zones are encountered in the underground structure. In the Sunni Dam project, 1.7m to 2m thick weak/shear zone comprising of deformed, weak material with gauge has been encountered in powerhouse cavern at 70m having dip direction 325 degree and dip amount 38 degree which also intersects transformer hall at initial reach. The rock encountered in the powerhouse area is moderate to highly jointed, pink quartz arenite belonging to the Khaira Formation, a transition zone comprising of alternate grey, pink & white quartz arenite and shale sequence and dolomite at higher reaches. The rock mass is intersected by mainly 3 joint sets excluding bedding joints and a few random joints. The rock class in powerhouse mainly varies from poor class (class IV) to lower order fair class (class III) and in some reaches, very poor rock mass has also been encountered. To study the stability of the underground structure in weak/shear rock mass, a 3D numerical model analysis has been carried out using RS3 software. Field studies have been interpreted and analysed to derive Bieniawski’s RMR, Barton’s “Q” class and Geological Strength Index (GSI). The various material parameters, in-situ characteristics have been determined based on tests conducted by Central Soil and Materials Research Station, New Delhi. The behaviour of the cavern has been studied by assessing the displacement contours, major and minor principal stresses and plastic zones for different stage excavation sequences. For optimisation of the support system, the stability of the powerhouse cavern with different powerhouse orientations has also been studied. The numerical modeling results indicate that cavern will not likely face stress governed by structural instability with the support system to be applied to the crown and side walls.

Keywords: 3D analysis, Himalayan geology, shear zone, underground power house

Procedia PDF Downloads 58

Authors: Evgeniya Orlova, Dmitriy Feoktistov, Geniy Kuznetsov

Abstract:

Spreading of a droplet over a solid substrate is a key phenomenon observed in the following engineering applications: thin film coating, oil extraction, inkjet printing, and spray cooling of heated surfaces. Droplet cooling systems are known to be more effective than film or rivulet cooling systems. It is caused by the greater evaporation surface area of droplets compared with the film of the same mass and wetting surface. And the greater surface area of droplets is connected with the curvature of the interface. Location of the droplets on the cooling surface influences on the heat transfer conditions. The close distance between the droplets provides intensive heat removal, but there is a possibility of their coalescence in the liquid film. The long distance leads to overheating of the local areas of the cooling surface and the occurrence of thermal stresses. To control the location of droplets is possible by changing the roughness, structure and chemical composition of the surface. Thus, control of spreading can be implemented. The most important characteristic of spreading of droplets on solid surfaces is a dynamic contact angle, which is a function of the contact line speed or capillary number. However, there is currently no universal equation, which would describe the relationship between these parameters. This paper presents the results of the experimental studies of water droplet spreading on metal substrates with different surface roughness. The effect of the droplet growth rate and the surface roughness on spreading characteristics was studied at low capillary numbers. The shadow method using high speed video cameras recording up to 10,000 frames per seconds was implemented. A droplet profile was analyzed by Axisymmetric Drop Shape Analyses techniques. According to change of the dynamic contact angle and the contact line speed three sequential spreading stages were observed: rapid increase in the dynamic contact angle; monotonous decrease in the contact angle and the contact line speed; and form of the equilibrium contact angle at constant contact line. At low droplet growth rate, the dynamic contact angle of the droplet spreading on the surfaces with the maximum roughness is found to increase throughout the spreading time. It is due to the fact that the friction force on such surfaces is significantly greater than the inertia force; and the contact line is pinned on microasperities of a relief. At high droplet growth rate the contact angle decreases during the second stage even on the surfaces with the maximum roughness, as in this case, the liquid does not fill the microcavities, and the droplet moves over the “air cushion”, i.e. the interface is a liquid/gas/solid system. Also at such growth rates pulsation of liquid flow was detected; and the droplet oscillates during the spreading. Thus, obtained results allow to conclude that it is possible to control spreading by using the surface roughness and the growth rate of droplets on surfaces as varied factors. Also, the research findings may be used for analyzing heat transfer in rivulet and drop cooling systems of high energy equipment.

Keywords: contact line speed, droplet growth rate, dynamic contact angle, shadow system, spreading

Procedia PDF Downloads 298

Authors: Maciej Szeląg, Stanisław Fic

Abstract:

The impact of elevated temperatures on the construction materials manifests in change of their physical and mechanical characteristics. Stresses and thermal deformations that occur inside the volume of the material cause its progressive degradation as temperature increase. Finally, the reactions and transformations of multiphase structure of cementitious composite cause its complete destruction. A particularly dangerous phenomenon is the impact of thermal shock – a sudden high temperature load. The thermal shock leads to a high value of the temperature gradient between the outer surface and the interior of the element in a relatively short time. The result of mentioned above process is the formation of the cracks and scratches on the material’s surface and inside the material. The article describes the use of computer image analysis techniques to identify and assess the structure of the cluster cracks on the surfaces of modified cement pastes, caused by thermal shock. Four series of specimens were tested. Two Portland cements were used (CEM I 42.5R and CEM I 52,5R). In addition, two of the series contained metakaolinite as a replacement for 10% of the cement content. Samples in each series were made in combination of three w/b (water/binder) indicators of respectively 0.4; 0.5; 0.6. Surface cracks of the samples were created by a sudden temperature load at 200°C for 4 hours. Images of the cracked surfaces were obtained via scanning at 1200 DPI; digital processing and measurements were performed using ImageJ v. 1.46r software. In order to examine the cracked surface of the cement paste as a system of closed clusters – the dispersal systems theory was used to describe the structure of cement paste. Water is used as the dispersing phase, and the binder is used as the dispersed phase – which is the initial stage of cement paste structure creation. A cluster itself is considered to be the area on the specimen surface that is limited by cracks (created by sudden temperature loading) or by the edge of the sample. To describe the structure of cracks two stereological parameters were proposed: A ̅ – the cluster average area, L ̅ – the cluster average perimeter. The goal of this study was to compare the investigated stereological parameters with the mechanical properties of the tested specimens. Compressive and tensile strength testes were carried out according to EN standards. The method used in the study allowed the quantitative determination of defects occurring in the examined modified cement pastes surfaces. Based on the results, it was found that the nature of the cracks depends mainly on the physical parameters of the cement and the intermolecular interactions on the dispersal environment. Additionally, it was noted that the A ̅/L ̅ relation of created clusters can be described as one function for all tested samples. This fact testifies about the constant geometry of the thermal cracks regardless of the presence of metakaolinite, the type of cement and the w/b ratio.

Keywords: cement paste, cluster cracks, elevated temperature, image analysis, metakaolinite, stereological parameters

Procedia PDF Downloads 363

Authors: Stojan Kravanja, Andrej Ivanič, Tomaž Žula

Abstract:

This contribution focuses on structural optimization in civil engineering using mixed integer non-linear programming (MINLP). MINLP is characterized as a versatile method that can handle both continuous and discrete optimization variables simultaneously. Continuous variables are used to optimize parameters such as dimensions, stresses, masses, or costs, while discrete variables represent binary decisions to determine the presence or absence of structural elements within a structure while also calculating discrete materials and standard sections. The optimization process is divided into three main steps. First, a mechanical superstructure with a variety of different topology-, material- and dimensional alternatives. Next, a MINLP model is formulated to encapsulate the optimization problem. Finally, an optimal solution is searched in the direction of the defined objective function while respecting the structural constraints. The economic or mass objective function of the material and labor costs of a structure is subjected to the constraints known from structural analysis. These constraints include equations for the calculation of internal forces and deflections, as well as equations for the dimensioning of structural components (in accordance with the Eurocode standards). Given the complex, non-convex and highly non-linear nature of optimization problems in civil engineering, the Modified Outer-Approximation/Equality-Relaxation (OA/ER) algorithm is applied. This algorithm alternately solves subproblems of non-linear programming (NLP) and main problems of mixed-integer linear programming (MILP), in this way gradually refines the solution space up to the optimal solution. The NLP corresponds to the continuous optimization of parameters (with fixed topology, discrete materials and standard dimensions, all determined in the previous MILP), while the MILP involves a global approximation to the superstructure of alternatives, where a new topology, materials, standard dimensions are determined. The optimization of a convex problem is stopped when the MILP solution becomes better than the best NLP solution. Otherwise, it is terminated when the NLP solution can no longer be improved. While the OA/ER algorithm, like all other algorithms, does not guarantee global optimality due to the presence of non-convex functions, various modifications, including convexity tests, are implemented in OA/ER to mitigate these difficulties. The effectiveness of the proposed MINLP approach is demonstrated by its application to various structural optimization tasks, such as mass optimization of steel buildings, cost optimization of timber halls, composite floor systems, etc. Special optimization models have been developed for the optimization of these structures. The MINLP optimizations, facilitated by the user-friendly software package MIPSYN, provide insights into a mass or cost-optimal solutions, optimal structural topologies, optimal material and standard cross-section choices, confirming MINLP as a valuable method for the optimization of structures in civil engineering.

Keywords: MINLP, mixed-integer non-linear programming, optimization, structures

Procedia PDF Downloads 13

Authors: Thayalan Nall, Harry Poulos

Abstract:

Piling is the most widely used foundation method for heavy structures in poor soil conditions. The geotechnical engineer can choose among a variety of piling methods, but in most cases, driving piles by impact hammer is the most cost-effective alternative. Under unfavourable conditions, driving piles can cause environmental problems, such as noise, ground movements and vibrations, with the risk of ground disturbance leading to potential damage to proposed structures. In one of the project sites in which the authors were involved, three offshore container terminals, namely CT1, CT2 and CT3, were constructed over thick compressible marine mud. The seabed was around 6m deep and the soft clay thickness within the project site varied between 9m and 20m. CT2 and CT3 were connected together and rectangular in shape and were 2600mx800m in size. CT1 was 400m x 800m in size and was located on south opposite of CT2 towards its eastern end. CT1 was constructed first and due to time and environmental limitations, it was supported on a “forest” of large diameter driven piles. CT2 and CT3 are now under construction and are being carried out using a traditional dredging and reclamation approach with ground improvement by surcharging with vertical drains. A few months after the installation of the CT1 piles, a 2600m long sand bund to 2m above mean sea level was constructed along the southern perimeter of CT2 and CT3 to contain the dredged mud that was expected to be pumped. The sand bund was constructed by sand spraying and pumping using a dredging vessel. About 2000m length of the sand bund in the west section was constructed without any major stability issues or any noticeable distress. However, as the sand bund approached the section parallel to CT1, it underwent a series of deep seated failures leading the displaced soft clay materials to heave above the standing water level. The crest of the sand bund was about 100m away from the last row of piles. There were no plausible geological reasons to conclude that the marine mud only across the CT1 region was weaker than over the rest of the site. Hence it was suspected that the pile driving by impact hammer may have caused ground movements and vibrations, leading to generation of excess pore pressures and cyclic softening of the marine mud. This paper investigates the probable cause of failure by reviewing: (1) All ground investigation data within the region; (2) Soil displacement caused by pile driving, using theories similar to spherical cavity expansion; (3) Transfer of stresses and vibrations through the entire system, including vibrations transmitted from the hammer to the pile, and the dynamic properties of the soil; and (4) Generation of excess pore pressure due to ground vibration and resulting cyclic softening. The evidence suggests that the problems encountered at the site were primarily caused by the “side effects” of the pile driving operations.

Keywords: pile driving, ground vibration, excess pore pressure, cyclic softening

Procedia PDF Downloads 206

Authors: Genevieve Jorolan-Quintero

Abstract:

The recording as well as the preservation of indigenous literature is an important task as it deals with a significant heritage of pre-colonial culture. The beliefs and traditions of a people are reflected in their oral narratives, such as the folk epic, which must be written down to insure their preservation. The epic poem for instance, known as dawot among the Mandaya, one of the indigenous communities in the southern region of the Philippines, narrates the customs, the ways of life, and the adventures of an ancient people. Nabayra, an expert on Philippine folkloric studies, stresses that still extant after centuries of unknown origin, the dawot was handed down to the magdadawot (bard) by word of mouth, forming the greatest bulk of Mandaya oral tradition. Unhampered by modern means of communication to distract her/him, the magdadawot has a sharp memory of the intricacies of the ancient art of chanting the panayday (verses) of the epic poem. The dawot has several hullubaton (episodes), each of which takes several nights to chant . The language used in these oral traditions is archaic Mandaya, no longer spoken or clearly understood by the present generation. There is urgency to the task of recording and writing down what remain of the epic poem since the singers and storytellers who have retained the memory and the skill of chanting and narrating the dawot and other forms of oral tradition in their original forms are getting fewer. The few who are gifted and skilled to transmit these ancient arts and wisdom are old and dying. Unlike the other Philippine epics (i.e. the Darangen, the Ulahingan, the Hinilawod, etc.), the Mandaya epic is yet to be recognized and given its rightful place among the recorded epics in Philippine Folk Literature. The general aim of this study was to put together and preserve an intangible heritage, the Mandaya hullubaton (episodes of the dawot), in order to preserve and promote appreciation for the oral traditions and cultural legacy of the Mandaya. It was able to record, transcribe, and translate four hullubaton of the folk epic into two languages, Visayan and English to insure understanding of their contents and significance among non-Mandaya audiences. Evident in the contents of the episodes are the cultural practices, ideals, life values, and traditions of the ancient Mandaya. While the conquests and adventures of the Mandaya heroes Lumungtad, Dilam, and Gambong highlight heroic virtues, the role of the Mandaya matriarch in family affairs is likewise stressed. The recording and the translation of the hullubaton and the dawot into commonly spoken languages will not only promote knowledge and understanding about their culture, but will also stimulate in the members of this cultural community a sense of pride for their literature and culture. Knowledge about indigenous cultural system and philosophy derived from their oral literature will serve as a springboard to further comparative researches dealing with indigenous mores and belief systems among the different tribes in the Philippines, in Asia, in Africa, and other countries in the world.

Keywords: Dawot, epic poem, Mandaya, Philippine folk literature

Procedia PDF Downloads 381

Authors: Rosa Palmeri, Julieta I. Monteleone, Antonio C. Barbera, Carmelo Maucieri, Aldo Todaro, Virgilio Giannone, Giovanni Spagna

Abstract:

In recent years, considerable interest has been shown in the functional properties of foods, and a relevant role has been played by phenolic compounds, able to scavenge free radicals. A more sustainable agriculture has to emerge to guarantee food supply over the next years. Wheat, corn, and rice are the most common cereals cultivated, but also other cereal species, such as barley can be appreciated for their peculiarities. Barley (Hordeum vulgare L.) is a C3 winter cereal that shows high resistance at drought and salt stresses. There are growing interests in barley as ingredient for the production of functional foods due to its high content of phenolic compounds and Beta-glucans. In this respect, the possibility of separating specific functional fractions from food industry by-products looks very promising. Olive leaves represent a quantitatively significant by-product of olive grove farming, and are an interesting source of phenolic compounds. In particular, oleuropein, which provide important nutritional benefits, is the main phenolic compound in olive leaves and ranges from 17% to 23% depending upon the cultivar and growing season period. Together with oleuropein and its derivatives (e.g. dimethyloleuropein, oleuropein diglucoside), olive leaves further contain tyrosol, hydroxytyrosol, and a series of secondary metabolities structurally related to them: verbascoside, ligstroside, hydroxytyrosol glucoside, tyrosol glucoside, oleuroside, oleoside-11-methyl ester, and nuzhenide. Several flavonoids, flavonoid glycosides, and phenolic acids have also described in olive leaves. The aim of this work was the production of functional food with higher content of polyphenols and the evaluation of their shelf life. Organic durum wheat and barley grains contain higher levels of phenolic compounds were used for the production of crackers. Olive leaf extract (OLE) was obtained from cv. ‘Biancolilla’ by aqueous extraction method. Two baked goods trials were performed with both organic durum wheat and barley flours, adding olive leaf extract. Control crackers, made as comparison, were produced with the same formulation replacing OLE with water. Total phenolic compound, moisture content, activity water, and textural properties at different time of storage were determined to evaluate the shelf-life of the products. Our the preliminary results showed that the enriched crackers showed higher phenolic content and antioxidant activity than control. Alternative uses of olive leaf extracts for crackers production could represent a good candidate for the addition of functional ingredients because bakery items are daily consumed, and have long shelf-life.

Keywords: barley, functional foods, olive leaf, polyphenols, shelf life

Procedia PDF Downloads 274

Authors: Chettyparambil Lalchand Thejalakshmi, Sonal Sabu Edattukaran

Abstract:

Hair loss is one of the main issues that contemporary society is dealing with. It can be attributable to a wide range of factors, listing from one's genetic composition and the anxiety we experience on a daily basis. Telogen effluvium [TE] is a condition that causes temporary hair loss after a stressor that might shock the body and cause the hair follicles to temporarily rest, leading to hair loss. Most frequently, women are the ones who bring up these difficulties. Extreme illness or trauma, an emotional or important life event, rapid weight loss and crash dieting, a severe scalp skin problem, a new medication, or ceasing hormone therapy are examples of potential causes. Men frequently do not notice hair thinning with time, but women with long hair may be easily identified when shedding, which can occasionally result in bias because women tend to be more concerned with aesthetics and beauty standards of the society, and approach frequently with the concerns .The woman, who formerly possessed a full head of hair, is worried about the hair loss from her scalp . There are several cases of hair loss reported every day, and Telogen effluvium is said to be the most prevalent one of them all without any hereditary risk factors. While the patient has loss in hair volume, baldness is not the result of this problem . The exponentially growing Dermatology and Aesthetic medical division has discovered that this problem is the most common and also the easiest to cure since it is feasible for these people to regrow their hair, unlike those who have scarring alopecia, in which the follicle itself is damaged and non-viable. Telogen effluvium comes in two different forms: acute and chronic. Acute TE occurs in all the age groups with a hair loss of less than three months, while chronic TE is more common in those between the ages of 30 and 60 with a hair loss of more than six months . Both kinds are prevalent throughout all age groups, regardless of the predominance. It takes between three and six months for the lost hair to come back, although this condition is readily reversed by eliminating stresses. After shedding their hair, patients frequently describe having noticeable fringes on their forehead. The current medical treatments for this condition include topical corticosteroids, systemic corticosteroids, minoxidil and finasteride, CNDPA (caffeine, niacinamide, panthenol, dimethicone, and an acrylate polymer) .Individual terminal hair growth was increased by 10% as a result of the innovative intervention CNDPA. Botulinum Toxin A, Scalp Micro Needling, Platelet Rich Plasma Therapy [PRP], and sessions with Multivitamin Mesotherapy Injections are some recently enhanced techniques with partially or completely reversible hair loss. Also, it has been shown that supplements like Nutrafol and Biotin are producing effective outcomes. There is virtually little evidence to support the claim that applying sulfur-rich ingredients to the scalp, such as onion juice, can help TE patients' hair regenerate.

Keywords: dermatology, telogen effluvium, hair loss, modern hair loass treatments

Procedia PDF Downloads 64

Authors: Naziema Jappie

Abstract:

South Africa is a diverse nation but with many challenges. The fundamental changes in the political, economic and educational domains in South Africa in the late 1990s affected the South African community profoundly. In higher education, experiences of discrimination and bias are detrimental to the sense of belonging of staff and students. It is therefore important to cultivate an appreciation of diversity and inclusion. To bridge common understandings with the reality of racial inequality, we must understand the ways in which senior and executive leadership at universities think about social justice issues relating to diversity and inclusion and contextualize these within the current post-democracy landscape. The position and status of social justice issues and initiatives in South African higher education is a slow process. The focus is to highlight how and to what extent initiatives or practices around campus diversity and inclusion have been considered and made part of the mainstream intellectual and academic conversations in South Africa. This involves an examination of the social and epistemological conditions of possibility for meaningful research and curriculum practices, staff and student recruitment, and student access and success in addressing the challenges posed by social diversity on campuses. Methodology: In this study, university senior and executive leadership were interviewed about their perceptions and advancement of social justice and examine the buffering effects of diverse and inclusive peer interactions and institutional commitment on the relationship between discrimination–bias and sense of belonging for staff and students at the institutions. The paper further explores diversity and inclusion initiatives at the three institutions using a Critical Race Theory approach in conjunction with a literature review on social justice with a special focus on diversity and inclusion. Findings: This paper draws on research findings that demonstrate the need to address social justice issues of diversity and inclusion in the SA higher education context. The reason for this is so that university leaders can live out their experiences and values as they work to transform students into being accountable and responsible. Documents were selected for review with the intent of illustrating how diversity and inclusion work being done across an institution can shape the experiences of previously disadvantaged persons at these institutions. The research has highlighted the need for institutional leaders to embody their own mission and vision as they frame social justice issues for the campus community. Finally, the paper provides recommendations to institutions for strengthening high-level diversity and inclusion programs/initiatives among staff, students and administrators. The conclusion stresses the importance of addressing the historical and current policies and practices that either facilitate or negate the goals of social justice, encouraging these privileged institutions to create internal committees or task forces that focus on racial and ethnic disparities in the institution.

Keywords: diversity, higher education, inclusion, social justice

Procedia PDF Downloads 95

Authors: E. A. Abdel-Hakim

Abstract:

The corn stemborer Sesamia cretica (Lederer), has been viewed in many parts of the world as a major pest of cultivated maize, graminaceous crops and sugarcane. Its life cycle is comprised of two different phases, one is the growth and developmental phase (non-diapause) and the other is diapause phase which takes place at the last larval instar. Several problems associated with the use of conventional insecticides, have strongly demonstrated the need for applying alternative safe compounds. Prominent among the prototypes of such prospective chemicals are the juvenoids; i.e. the insect (JH) mimics. In fact, the hormonal effect on metabolism has long been viewed as a secondary consequence of its direct action on specific energy-requiring biosynthetic mechanisms. Therefore, the present study was undertaken essentially in a rather systematic fashion as a contribution towards clarifying metabolic and energetic changes taking place during non-diapause wandering larvae as regulated by (JH) mimic. For this purpose, we applied two different doses of JH mimic (Ro 11-0111) in a single (standard) dose of 100µg or in a single dose of 20 µg/g bw in1µl acetone topically at the onset of nondiapause wandering larvae (WL). Energetic data were obtained by indirect calorimetry methods by conversion of respiratory gas exchange volumetric data, as measured manometrically using a Warburg constant respirometer, to caloric units (g-cal/g fw/h). The findings obtained can be given in brief; these treated larvae underwent supernumerary larval moults. However, this potential the wandering larvae proved to possess whereby restoration of larval programming for S. cretica to overcome stresses even at this critical developmental period. The results obtained, particularly with the high dose used, show that 98% wandering larvae were rescued to survive up to one month (vs. 5 days for normal controls), finally the formation of larval-adult intermediates. Also, the solvent controls had resulted in about 22% additional, but stationary moultings. The basal respiratory metabolism (O2 uptake and CO2 output) of the (WL), whether un-treated or larvae not had followed reciprocal U-shaped curves all along of their developmental duration. The lowest points stood nearly to the day of prepupal formation (571±187 µl O2/gfw/h and 553±181 µl CO2/gfw/h) during un-treated in contrast to the larvae treated with JH (210±48 µl O2/gfw/h and 335±81 µl CO2/gfw/h). Un-treated (normal) larvae proved to utilize carbohydrates as the principal source for energy supply; being fully oxidised without sparing any appreciable amount for endergonic conversion to fats. While, the juvenoid-treated larvae and compared with the acetone-treated control equivalents, there existed no distinguishable differences between them; both had been observed utilising carbohydrates as the sole source of energy demand and converting endergonically almost similar percentages to fats. The overall profile, treated and un-treated (WL) utilized carbohydrates as the principal source for energy demand during this stage.

Keywords: juvenile hormone, respiratory metabolism, Sesamia cretica, wandering phase

Procedia PDF Downloads 269

Authors: Shamsulhaq Amin

Abstract:

Unbound granular materials (UGMs) are pivotal in ensuring long-term quality, especially in the layers under the surface of flexible pavements and other constructions. This study seeks to better understand the behavior of the UGMs by looking at popular models for predicting lasting deformation under various levels of stresses and load cycles. These models focus on variables such as the number of load cycles, stress levels, and features specific to materials and were evaluated on the basis of their ability to accurately predict outcomes. The study showed that these factors play a crucial role in how well the models work. Therefore, the research highlights the need to look at a wide range of stress situations to more accurately predict how much the UGMs bend or shift. The research looked at important factors, like how permanent deformation relates to the number of times a load is applied, how quickly this phenomenon happens, and the shakedown effect, in two different types of UGMs: granite and limestone. A detailed study was done over 100,000 load cycles, which provided deep insights into how these materials behave. In this study, a number of factors, such as the level of stress applied, the number of load cycles, the density of the material, and the moisture present were seen as the main factors affecting permanent deformation. It is vital to fully understand these elements for better designing pavements that last long and handle wear and tear. A series of laboratory tests were performed to evaluate the mechanical properties of materials and acquire model parameters. The testing included gradation tests, CBR tests, and Repeated load triaxial tests. The repeated load triaxial tests were crucial for studying the significant components that affect deformation. This test involved applying various stress levels to estimate model parameters. In addition, certain model parameters were established by regression analysis, and optimization was conducted to improve outcomes. Afterward, the material parameters that were acquired were used to construct graphs for each model. The graphs were subsequently compared to the outcomes obtained from the repeated load triaxial testing. Additionally, the models were evaluated to determine if they demonstrated the two inherent deformation behaviors of materials when subjected to repetitive load: the initial phase, post-compaction, and the second phase volumetric changes. In this study, using log-log graphs was key to making the complex data easier to understand. This method made the analysis clearer and helped make the findings easier to interpret, adding both precision and depth to the research. This research provides important insight into picking the right models for predicting how these materials will act under expected stress and load conditions. Moreover, it offers crucial information regarding the effect of load cycle and permanent deformation as well as the shakedown effect on granite and limestone UGMs.

Keywords: permanent deformation, unbound granular materials, load cycles, stress level

Procedia PDF Downloads 10

Authors: Mona Kamel Hassan

Abstract:

Teaching a class of diverse learners poses a great challenge not only for foreign and second language teachers, but also for teachers in different disciplines as well as for curriculum designers. Thus, to contribute to previous research tackling language diversity, the current paper shares the experience of teaching a reading, writing and vocabulary building course to diverse Arabic as a Foreign Language learners in their advanced language proficiency level. Diversity is represented in students’ motivation, their prior knowledge, their various needs and interests, their level of anxiety, and their different learning styles and skills. While teaching this course the researcher adopted the universal design for learning (UDL) framework, which is a means to meet the various needs of diverse learners. UDL stresses the importance of enabling the entire diverse students to gain skills, knowledge, and enthusiasm to learn through the employment of teaching methods that respond to students' individual differences. Accordingly, the educational curriculum developed for this course and the teaching methods employed is modified. First, the researcher made the language curriculum vivid and attractive to inspire students' learning and to keep them engaged in their learning process. The researcher encouraged the entire students, from the first day, to suggest topics of their interest; political, social, cultural, etc. The authentic Arabic texts chosen are those that best meet students’ needs, interests, lives, and sociolinguistic issues, together with the linguistic and cultural components. In class and under the researcher’s guidance, students dig into these topics to find solutions for the tackled issues while working with their peers. Second, to gain equal opportunities to demonstrate learning, role-playing was encouraged to give students the opportunity to perform different linguistic tasks, to reflect and share their diverse interests and cultural backgrounds with their peers. Third, to bring the UDL into the classroom, students were encouraged to work on interactive, collaborative activities through technology to improve their reading and writing skills and reinforce their mastery of the accumulated vocabulary, idiomatic expressions, and collocations. These interactive, collaborative activities help to facilitate student-student communication and student-teacher communication and to increase comfort in this class of diverse learners. Detailed samples of the educational curriculum and interactive, collaborative activities developed, accompanied by methods of teaching employed to teach these diverse learners, are presented for illustration. Results revealed that students are responsive to the educational materials which are developed for this course. Therefore, they engaged in the learning process and classroom activities and discussions effectively. They also appreciated their instructor’s willingness to differentiate the teaching methods to suit students of diverse background knowledge, learning styles, level of anxiety, etc. Finally, the researcher believes that sharing this experience in teaching diverse learners will help both language teachers and teachers in other disciplines to develop a better understanding to meet their students' diverse needs. Results will also pave the way for curriculum designers to develop educational material that meets the needs of diverse learners.

Keywords: teaching, language, diverse, learners

Procedia PDF Downloads 70

Authors: Masoud Mirzaee, Ghobad Behzadi Pour

Abstract:

An aircraft tire is designed to tolerate extremely heavy loads for a short duration. The number of tires increases with the weight of the aircraft, as it is needed to be distributed more evenly. Generally, aircraft tires work at high pressure, up to 200 psi (14 bar; 1,400 kPa) for airliners and higher for business jets. Tire assemblies for most aircraft categories provide a recommendation of compressed nitrogen that supports the aircraft’s weight on the ground, including a mechanism for controlling the aircraft during taxi, takeoff; landing; and traction for braking. Accurate tire pressure is a key factor that enables tire assemblies to perform reliably under high static and dynamic loads. Concerning ambient temperature change, considering the condition in which the temperature between the origin and destination airport was different, tire pressure should be adjusted and inflated to the specified operating pressure at the colder airport. This adjustment superseding the normal tire over an inflation limit of 5 percent at constant ambient temperature is required because the inflation pressure remains constant to support the load of a specified aircraft configuration. On the other hand, without this adjustment, a tire assembly would be significantly under/over-inflated at the destination. Due to an increase of human errors in the aviation industry, exorbitant costs are imposed on the airlines for providing consumable parts such as aircraft tires. The existence of an intelligent system to adjust the aircraft tire pressure based on weight, load, temperature, and weather conditions of origin and destination airports, could have a significant effect on reducing the aircraft maintenance costs, aircraft fuel and further improving the environmental issues related to the air pollution. An intelligent tire pressure regulation system (ITPRS) contains a processing computer, a nitrogen bottle with 1800 psi, and distribution lines. Nitrogen bottle’s inlet and outlet valves are installed in the main wheel landing gear’s area and are connected through nitrogen lines to main wheels and nose wheels assy. Controlling and monitoring of nitrogen will be performed by a computer, which is adjusted according to the calculations of received parameters, including the temperature of origin and destination airport, the weight of cargo loads and passengers, fuel quantity, and wind direction. Correct tire inflation and deflation are essential in assuring that tires can withstand the centrifugal forces and heat of normal operations, with an adequate margin of safety for unusual operating conditions such as rejected takeoff and hard landings. ITPRS will increase the performance of the aircraft in all phases of takeoff, landing, and taxi. Moreover, this system will reduce human errors, consumption materials, and stresses imposed on the aircraft body.

Keywords: avionic system, improve efficiency, ITPRS, human error, reduced cost, tire pressure

Procedia PDF Downloads 208

Authors: Markandeya Kunchi

Abstract:

Usability testing (UT) is one of the vital steps in the User-centred design (UCD) process when designing a product. In an e-commerce ecosystem, UT becomes primary as new products, features, and services are launched very frequently. And, there are losses attached to the company if an unusable and inefficient product is put out to market and is rejected by customers. This paper tries to answer why UT is important in the product life-cycle of an E-commerce ecosystem. Secondary user research was conducted to find out work patterns, development methods, type of stakeholders, and technology constraints, etc. of a typical E-commerce company. Qualitative user interviews were conducted with product managers and designers to find out the structure, project planning, product management method and role of the design team in a mid-level company. The paper tries to address the usual apprehensions of the company to inculcate UT within the team. As well, it stresses upon factors like monetary resources, lack of usability expert, narrow timelines, and lack of understanding of higher management as some primary reasons. Outsourcing UT to vendors is also very prevalent with mid-level e-commerce companies, but it has its own severe repercussions like very little team involvement, huge cost, misinterpretation of the findings, elongated timelines, and lack of empathy towards the customer, etc. The shortfalls of the unavailability of a UT process in place within the team and conducting UT through vendors are bad user experiences for customers while interacting with the product, badly designed products which are neither useful and nor utilitarian. As a result, companies see dipping conversions rates in apps and websites, huge bounce rates and increased uninstall rates. Thus, there was a need for a more lean UT system in place which could solve all these issues for the company. This paper highlights on optimizing the UT process with a collaborative method. The degree of optimization and structure of collaborative method is the highlight of this paper. Collaborative method of UT is one in which the centralised design team of the company takes for conducting and analysing the UT. The UT is usually a formative kind where designers take findings into account and uses in the ideation process. The success of collaborative method of UT is due to its ability to sync with the product management method employed by the company or team. The collaborative methods focus on engaging various teams (design, marketing, product, administration, IT, etc.) each with its own defined roles and responsibility in conducting a smooth UT with users In-house. The paper finally highlights the positive results of collaborative UT method after conducting more than 100 In-lab interviews with users across the different lines of businesses. Some of which are the improvement of interaction between stakeholders and the design team, empathy towards users, improved design iteration, better sanity check of design solutions, optimization of time and money, effective and efficient design solution. The future scope of collaborative UT is to make this method leaner, by reducing the number of days to complete the entire project starting from planning between teams to publishing the UT report.

Keywords: collaborative method, e-commerce, product management method, usability testing

Procedia PDF Downloads 94

Authors: Ramprasad Srinivasan

Abstract:

Engineers create inventions and put their ideas in concrete terms to design new products. Design drivers must be established, which requires, among other things, a complete understanding of the product design, load paths, etc. For Aerospace Vehicles, weight/strength ratio, strength, stiffness and stability are the important design drivers. A complex built-up structure is made up of an assemblage of primitive structural forms of arbitrary shape, which include 1D structures like beams and frames, 2D structures like membranes, plate and shell structures, and 3D solid structures. Justification through simulation involves a check for all the quantities of interest, namely stresses, deformation, frequencies, and buckling loads and is normally achieved through the finite element (FE) method. Over the past few decades, Fiber-reinforced composites are fast replacing the traditional metallic structures in the weight-sensitive aerospace and aircraft industries due to their high specific strength, high specific stiffness, anisotropic properties, design freedom for tailoring etc. Composite panel constructions are used in aircraft to design primary structure components like wings, empennage, ailerons, etc., while thin-walled composite beams (TWCB) are used to model slender structures like stiffened panels, helicopter, and wind turbine rotor blades, etc. The TWCB demonstrates many non-classical effects like torsional and constrained warping, transverse shear, coupling effects, heterogeneity, etc., which makes the analysis of composite structures far more complex. Conventional FE formulations to model 1D structures suffer from many limitations like shear locking, particularly in slender beams, lower convergence rates due to material coupling in composites, inability to satisfy, equilibrium in the domain and natural boundary conditions (NBC) etc. For 2D structures, the limitations of conventional displacement-based FE formulations include the inability to satisfy NBC explicitly and many pathological problems such as shear and membrane locking, spurious modes, stress oscillations, lower convergence due to mesh distortion etc. This mandates frequent re-meshing to even achieve an acceptable mesh (satisfy stringent quality metrics) for analysis leading to significant cycle time. Besides, currently, there is a need for separate formulations (u/p) to model incompressible materials, and a single unified formulation is missing in the literature. Hence coupled field formulation (CFF) is a unified formulation proposed by the author for the solution of complex 1D and 2D structures addressing the gaps in the literature mentioned above. The salient features of CFF and its many advantages over other conventional methods shall be presented in this paper.

Keywords: coupled field formulation, kinematic and material coupling, natural boundary condition, locking free formulation

Procedia PDF Downloads 46

Authors: Min Wang, Hui Tian

Abstract:

Health promotion of high school students is essential for the construction of ‘Healthy China’, and increasing high school students’ physical activity is a must for their health promotion. School plays a crucial role in increasing high school students’ physical activity. Therefore, to have a comprehensive command of the school physical activity promotion strategies is of great significance for the health promotion of high school students in China and will shed some light on physical activity promotion worldwide. Literature review and interview survey are the main methods adopted for this research. It has been found that reforms of P.E. classes, improving the overall quality of P.E. teachers, and construction of school fields and facilities are among the major strategies to promote students’ physical activities. Even though it has been stipulated that primary and middle school students should take 3-4 times of P.E. classes per week, the execution is greatly influenced by the exam-oriented educational system. Randomly canceling P.E. classes or taking up the time to study other subjects is common, so it is difficult to guarantee the quantity of P.E. classes. According to national surveys, only 20%-40% of schools have 3-4 times of P.E. classes per week. In order to reduce the hindering effects of the exam-oriented educational system, a physical education test is included in the senior middle school entrance exam. The exam items include 1000m run for boys, 800m run for girls, and the basic skills for basketball/football/volleyball. The scores of the physical education test will greatly influence the admission of senior middle schools. China is now developing the ‘campus football’ policy and has established 20,000 football featured schools by 2017. Especially in these schools, football has become an important part of the students’ P.E. classes and a major means to promote students’ physical activity. As the Winter Olympics will be held in Beijing in 2022, China has promoted the ‘winter sports for all’ movement. The aim is to encourage 300 million people to winter sports, and the high school students are among the most potential participants. The primary and middle schools in Beijing have introduced winter sports to their P.E. curriculum, providing opportunities for the students to experience ice hockey and curling. Some Winter Olympics champions also go to the schools to popularize winter sports among the students. This greatly adds variety to the students’ physical activity regimen at school. In November 2017, seven ministries, including the General Administration of Sport of China and Ministry of Education of the People’s Republic of China, release Youth Sport Promotion Strategy. The strategy stipulates to strengthen the construction of youth sport facilities and implement the cultivation plan for P.E. teachers. It also emphasizes that school sport facilities should be open to students during holidays and vacations for free or at an affordable price. Overall speaking, the Chinese government stresses the importance of youth physical activity promotion and has issued a series of related policies and strategies, but the implementation still needs improvement.

Keywords: China, physical activity, promotion, school

Procedia PDF Downloads 79

Authors: Ali Ahmed Ali Al-Juboori, H. Zhu, D. Wexler, H. Li, C. Lu, J. McLeod, S. Pannila, J. Barnes

Abstract:

A number of studies have focused on the formation mechanics of white etching layer and its origin in the railway operation. Until recently, the following hypotheses consider the precise mechanics of WELs formation: (i) WELs are the result of thermal process caused by wheel slip; (ii) WELs are mechanically induced by severe plastic deformation; (iii) WELs are caused by a combination of thermo-mechanical process. The mechanisms discussed above lead to occurrence of white etching layers on the area of wheel and rail contact. This is because the contact patch which is the active point of the wheel on the rail is exposed to highest shear stresses which result in localised severe plastic deformation; and highest rate of heat caused by wheel slipe during excessive traction or braking effort. However, if the WELs are not on the running band area, it would suggest that there is another cause of WELs formation. In railway system, particularly electrified railway, arcing phenomenon has been occurring more often and regularly on the rails. In electrified railway, the current is delivered to the train traction motor via contact wires and then returned to the station via the contact between the wheel and the rail. If the contact between the wheel and the rail is temporarily losing, due to dynamic vibration, entrapped dirt or water, lubricant effect or oxidation occurrences, high current can jump through the gap and results in arcing. The other resources of arcing also include the wheel passage the insulated joint and lightning on a train during bad weather. During the arcing, an extensive heat is generated and speared over a large area of top surface of rail. Thus, arcing is considered another heat source in the rail head (rather than wheel slipe) that results in microstructural changes and white etching layer formation. A head hardened (HH) rail steel, cut from a curved rail truck was used for the investigation. Samples were sectioned from a depth of 10 mm below the rail surface, where the material is considered to be still within the hardened layer but away from any microstructural changes on the top surface layer caused by train passage. These samples were subjected to electrical discharges by using Gas Tungsten Arc Welding (GTAW) machine. The arc current was controlled and moved along the samples surface in the direction of travel, as indicated by an arrow. Five different conditions were applied on the surface of the samples. Samples containing pre-existed WELs, taken from ex-service rail surface, were also considered in this study for comparison. Both simulated and ex-serviced WELs were characterised by advanced methods including SEM, TEM, TKD, EDS, XRD. Samples for TEM and TKFD were prepared by Focused Ion Beam (FIB) milling. The results showed that both simulated WELs by electrical arcing and ex-service WEL comprise similar microstructure. Brown etching layer was found with WELs and likely induced by a concurrent tempering process. This study provided a clear understanding of new formation mechanics of WELs which contributes to track maintenance procedure.

Keywords: white etching layer, arcing, brown etching layer, material characterisation

Procedia PDF Downloads 97

Authors: C. Silveira, A. Ascenso, J. Ferreira, A. I. Miranda, P. Tuccella, G. Curci

Abstract:

Poor air quality is one of the main environmental causes of premature deaths worldwide, and mainly in cities, where the majority of the population lives. It is a consequence of successive land cover (LC) and use changes, as a result of the intensification of human activities. Knowing these landscape modifications in a comprehensive spatiotemporal dimension is, therefore, essential for understanding variations in air pollutant concentrations. In this sense, the use of air quality models is very useful to simulate the physical and chemical processes that affect the dispersion and reaction of chemical species into the atmosphere. However, the modelling performance should always be evaluated since the resolution of the input datasets largely dictates the reliability of the air quality outcomes. Among these data, the updated LC is an important parameter to be considered in atmospheric models, since it takes into account the Earth’s surface changes due to natural and anthropic actions, and regulates the exchanges of fluxes (emissions, heat, moisture, etc.) between the soil and the air. This work aims to evaluate the performance of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), when different LC classifications are used as an input. The influence of two LC classifications was tested: i) the 24-classes USGS (United States Geological Survey) LC database included by default in the model, and the ii) CLC (Corine Land Cover) and specific high-resolution LC data for Portugal, reclassified according to the new USGS nomenclature (33-classes). Two distinct WRF-Chem simulations were carried out to assess the influence of the LC on air quality over Europe and Portugal, as a case study, for the year 2015, using the nesting technique over three simulation domains (25 km², 5 km² and 1 km² horizontal resolution). Based on the 33-classes LC approach, particular emphasis was attributed to Portugal, given the detail and higher LC spatial resolution (100 m x 100 m) than the CLC data (5000 m x 5000 m). As regards to the air quality, only the LC impacts on tropospheric ozone concentrations were evaluated, because ozone pollution episodes typically occur in Portugal, in particular during the spring/summer, and there are few research works relating to this pollutant with LC changes. The WRF-Chem results were validated by season and station typology using background measurements from the Portuguese air quality monitoring network. As expected, a better model performance was achieved in rural stations: moderate correlation (0.4 – 0.7), BIAS (10 – 21µg.m^-3) and RMSE (20 – 30 µg.m^-3), and where higher average ozone concentrations were estimated. Comparing both simulations, small differences grounded on the Leaf Area Index and air temperature values were found, although the high-resolution LC approach shows a slight enhancement in the model evaluation. This highlights the role of the LC on the exchange of atmospheric fluxes, and stresses the need to consider a high-resolution LC characterization combined with other detailed model inputs, such as the emission inventory, to improve air quality assessment.

Keywords: land use, spatial resolution, WRF-Chem, air quality assessment

Procedia PDF Downloads 129

Authors: Helen Bartsch, Markus Feldmann

Abstract:

The dimensioning of steel structures subject to fatigue loads, such as wind turbines, bridges, masts and towers, crane runways and weirs or components in crane construction, is often dominated by fatigue verification. The fatigue details defined by the welded connections, such as butt or cruciform joints, longitudinal welds, welded-on or welded-in stiffeners, etc., are decisive. In Europe, the verification is usually carried out according to EN 1993-1-9 on a nominal stress basis. The basis is the detailed catalog, which specifies the fatigue strength of the various weld and construction details according to fatigue classes. Until now, a relation between fatigue classes and weld imperfection sizes is not included. Quality levels for imperfections in fusion-welded joints in steel, nickel, titanium and their alloys are regulated in EN ISO 5817, which, however, doesn’t contain direct correlations to fatigue resistances. The question arises whether some imperfections might be tolerable to a certain extent since they may be present in the test data used for detail classifications dating back decades ago. Although current standardization requires proof of satisfying limits of imperfection sizes, it would also be possible to tolerate welds with certain irregularities if these can be reliably quantified by non-destructive testing. Fabricators would be prepared to undertake carefully and sustained weld inspection in view of the significant economic consequences of such unfavorable fatigue classes. This paper presents investigations on the fatigue behavior of common welded details containing imperfections. In contrast to the common nominal stress concept, local fatigue concepts were used to consider the true stress increase, i.e., local stresses at the weld toe and root. The actual shape of a weld comprising imperfections, e.g., gaps or undercuts, can be incorporated into the fatigue evaluation, usually on a numerical basis. With the help of the effective notch stress concept, the fatigue resistance of detailed local weld shapes is assessed. Validated numerical models serve to investigate notch factors of fatigue details with different geometries. By utilizing parametrized ABAQUS routines, detailed numerical studies have been performed. Depending on the shape and size of different weld irregularities, fatigue classes can be defined. As well load-carrying welded details, such as the cruciform joint, as non-load carrying welded details, e.g., welded-on or welded-in stiffeners, are regarded. The investigated imperfections include, among others, undercuts, excessive convexity, incorrect weld toe, excessive asymmetry and insufficient or excessive throat thickness. Comparisons of the impact of different imperfections on the different types of fatigue details are made. Moreover, the influence of a combination of crucial weld imperfections on the fatigue resistance is analyzed. With regard to the trend of increasing efficiency in steel construction, the overall aim of the investigations is to include a more economical differentiation of fatigue details with regard to tolerance sizes. In the long term, the harmonization of design standards, execution standards and regulations of weld imperfections is intended.

Keywords: effective notch stress, fatigue, fatigue design, weld imperfections

Procedia PDF Downloads 228

Authors: Meilan Jin, Mary Jane Moran

Abstract:

This study aims to introduce the framework of culturally responsive home visiting (CRHV) to head start teacher professional sessions in the Southeastern of the US and investigate its influence on the evolving beliefs of teachers about their roles and relationships with families in-home visits. The framework orients teachers to an effective way of taking on the role of learner to listen for spoken and unspoken needs and look for family strengths. In addition, it challenges the deficit model that is grounded on 'cultural deprivation,' and it stresses the value of family cultures and advocates equal, collaborative parent-teacher relationships. The home visit reflection papers and focus group transcriptions of eight teachers have been collected since 2010 throughout a five-year longitudinal collaboration with them. Reflection papers were written by the teachers before and after introducing the CRHV framework, including the details of visit purposes and actions and their plans for later home visits. Particularly, the CRHV framework guided the teachers to listen and look for information about family-living environments; parent-child interactions; child-rearing practices; and parental beliefs, values, and needs. Two focus groups were organized in 2014 by asking the teachers to read their written reflection papers and then discussing their shared beliefs and experiences of home visits in recent years. The average length of the discussions was one hour, and the discussions were audio-recorded and transcribed verbatim. Moreover, the data were analyzed using constant comparative analysis, and the analysis was verified through (a) the uses of multiple data sources, (b) the involvement of multiple researchers, (c) coding checks, and (d) the provisions of the thick descriptions of the findings. The study findings corroborate that the teachers become to reposition themselves as 'knowledge seekers' through reorienting their cynosure toward 'setting stones' to learn, grow, and change rather than framing their home visits. The teachers also continually engage in careful listening, observing, questioning, and dialoguing, and these actions reflect their care toward parents. The value of teamwork with parents is advocated, and the teachers recognize that when parents feel empowered, they are active and committed to doing more for their children, which can further advantage proactive long-term parent-teacher collaborations. The study findings also validate that the framework is influential for educators to provide the experiences of home visiting that is culturally responsive and to share collaborative relationships with caregivers. The long-term impact of the framework further implies that teachers continue to put themselves in the position of evolving, including beliefs and actions, to better work with children and families who are culturally, ethnically, and linguistically different from them. This framework can be applicable to educators and professionals who are looking for avenues to bridge the relationship between home and school and parents and teachers.

Keywords: culturally responsive home visit, early childhood education, parent–teacher collaboration, teacher professional development

Procedia PDF Downloads 76

Authors: Andrew Gray, Zhibing Zhang

Abstract:

The ability for consumer products to deliver a sustained perfume response can be a key driver for a variety of applications. Many compounds in perfume oils are highly volatile, meaning they readily evaporate once the product is applied, and the longevity of the scent is poor. Perfume capsules have been introduced as a means of abating this evaporation once the product has been delivered. The impermeable capsules are aimed to be stable within the formulation, and remain intact during delivery to the desired substrate, only rupturing to release the core perfume oil through application of mechanical force applied by the consumer. This opens up the possibility of obtaining an olfactive response hours, weeks or even months after delivery, depending on the nature of the desired application. Tailoring the properties of the polymeric capsules to better address the needs of the application is not a trivial challenge and currently design of capsules is largely done by trial and error. The aim of this work is to have more predictive methods for capsule design depending on the consumer application. This means refining formulations such that they rupture at the right time for the specific consumer application, not too early, not too late. Finding the right balance between these extremes is essential if a benefit is sought with respect to neat addition of perfume to formulations. It is important to understand the forces that influence capsule rupture, first, by quantifying the magnitude of these different forces, and then by assessing bulk rupture in real-world applications to understand how capsules actually respond. Samples were provided by an industrial partner and the mechanical properties of individual capsules within the samples were characterized via a micromanipulation technique, developed by Professor Zhang at the University of Birmingham. The capsules were synthesized such as to change one particular physicochemical property at a time, such as core: wall material ratio, and the average size of capsules. Analysis of shell thickness via Transmission Electron Microscopy, size distribution via the use of a Mastersizer, as well as a variety of other techniques confirmed that only one particular physicochemical property was altered for each sample. The mechanical analysis was subsequently undertaken, showing the effect that changing certain capsule properties had on the response under compression. It was, however, important to link this fundamental mechanical response to capsule performance in real-world applications. As such, the capsule samples were introduced to a formulation and exposed to full scale stresses. GC-MS headspace analysis of the perfume oil released from broken capsules enabled quantification of what the relative strengths of capsules truly means for product performance. Correlations have been found between the mechanical strength of capsule samples and performance in terms of perfume release in consumer applications. Having a better understanding of the key parameters that drive performance benefits the design of future formulations by offering better guidelines on the parameters that can be adjusted without worrying about the performance effects, and singles out those parameters that are essential in finding the sweet spot for capsule performance.

Keywords: consumer products, mechanical and physicochemical properties, perfume capsules, rupture behaviour

Procedia PDF Downloads 111

Authors: S. Lahijanian, M. Mobli, B. Baninasab, N. Etemadi

Abstract:

Low temperature extremes are amongst the major stresses that adversely affect the plant growth and productivity. Cold stress causes oxidative stress, physiological, morphological and biochemical changes in plant cells. Generally, low temperatures similar to salinity and drought exert their negative effects mainly by disrupting the ionic and osmotic equilibrium of the plant cells. Changes in climatic condition leading to more frequent extreme conditions will require adapted crop species on a larger scale in order to sustain agricultural production. Eucalyptus is a diverse genus of flowering trees (and a few shrubs) in the myrtle family, Myrtaceae. Members of this genus dominate the tree flora of Australia. The eucalyptus genus contains more than 580 species and large number of cultivars, which are native to Australia. Large distribution and diversity of compatible eucalyptus cultivars reflect the fact of ecological flexibility of eucalyptus. Some eucalyptus cultivars can sustain hard environmental conditions like high and low temperature, salinity, high level of PH, drought, chilling and freezing which are intensively effective on crops with tropical and subtropical origin. In this study, we tried to evaluate freezing tolerance of 12 eucalyptus genotypes by means of four different morphological and physiological methods: Chlorophyll fluorescence, electrolyte leakage, proline and stomatal density. The studied cultivars include Eucalyptus camaldulensis, E. coccifera, E. darlympleana, E. erythrocorys, E. glaucescens, E. globulus, E. gunnii, E. macrocorpa, E. microtheca, E. rubida, E. tereticornis, and E. urnigera. Except for stomatal density recording, in other methods, plants were exposed to five gradual temperature drops: zero, -5, -10, -15 and -20 degree of centigrade and they remained in these temperatures for at least one hour. Experiment for measuring chlorophyll fluorescence showed that genotypes E. erythrocorys and E. camaldulensis were the most resistant genotypes and E. gunnii and E.coccifera were more sensitive than other genotypes to freezing stress effects. In electrolyte leakage experiment with regard to significant interaction between cultivar and temperature, genotypes E. erythrocorys and E.macrocorpa were shown to be the most tolerant genotypes and E. gunnii, E. urnigera, E. microtheca and E. tereticornis with the more ionic leakage percentage showed to be more sensitive to low temperatures. Results of Proline experiment approved that the most resistant genotype to freezing stress is E. erythrocorys. In the stomatal density experiment, the numbers of stomata under microscopic field were totally counted and the results showed that the E. erythrocorys and E. macrocorpa genotypes had the maximum and E. coccifera and E. darlympleana genotypes had minimum number of stomata under microscopic field (0.0605 mm2). In conclusion, E. erythrocorys identified as the most tolerant genotype; meanwhile E. gunnii classified as the most freezing susceptible genotype in this investigation. Further, remarkable correlation was not obtained between the stomatal density and other cold stress measures.

Keywords: chlorophyll fluorescence, cold stress, ionic leakage, proline, stomatal density

Procedia PDF Downloads 231

Authors: Asem Alhnity, Nicholas Pickett

Abstract:

The leisure home industry is experiencing an increase in sales due to the rise in popularity of staycations. However, there is also a demand for improvements in thermal and structural behaviour from customers. Existing standards and codes of practice outline the requirements for leisure home design. However, there is a lack of expertise in applying Finite Element Analysis (FEA) to complex structures in this industry. As a result, manufacturers rely on standardized design approaches, which often lead to excessively engineered or inadequately designed products. This study aims to address this issue by investigating the impact of the habitation structure on chassis performance in leisure homes. The aim of this research is to comprehensively analyse the impact of the habitation structure on chassis performance in leisure homes. By employing FEA on the entire unit, including both the habitation structure and the chassis, this study seeks to develop a novel framework for designing and analysing leisure homes. The objectives include material reduction, enhancing structural stability, resolving existing design issues, and developing innovative modular and wooden chassis designs. The methodology used in this research is quantitative in nature. The study utilizes FEA to analyse the performance of leisure home chassis under various loads. The analysis procedures involve running the FEA simulations on the numerical model of the leisure home chassis. Different load scenarios are applied to assess the stress and deflection performance of the chassis under various conditions. FEA is a numerical method that allows for accurate analysis of complex systems. The research utilizes flexible mesh sizing to calculate small deflections around doors and windows, with large meshes used for macro deflections. This approach aims to minimize run-time while providing meaningful stresses and deflections. Moreover, it aims to investigate the limitations and drawbacks of the popular approach of applying FEA only to the chassis and replacing the habitation structure with a distributed load. The findings of this study indicate that the popular approach of applying FEA only to the chassis and replacing the habitation structure with a distributed load overlooks the strengthening generated from the habitation structure. By employing FEA on the entire unit, it is possible to optimize stress and deflection performance while achieving material reduction and enhanced structural stability. The study also introduces innovative modular and wooden chassis designs, which show promising weight reduction compared to the existing heavily fabricated lattice chassis. In conclusion, this research provides valuable insights into the impact of the habitation structure on chassis performance in leisure homes. By employing FEA on the entire unit, the study demonstrates the importance of considering the strengthening generated from the habitation structure in chassis design. The research findings contribute to advancements in material reduction, structural stability, and overall performance optimization. The novel framework developed in this study promotes sustainability, cost-efficiency, and innovation in leisure home design.

Keywords: static homes, caravans, motor homes, holiday homes, finite element analysis (FEA)

Procedia PDF Downloads 56

Authors: Aymen Arfaoui, Abdelkader Soumaya, Noureddine Ben Ayed

Abstract:

The study region is located in the Tunisian Dorsal Backland (Central Mediterranean), which is the easternmost part of the Saharan Atlas mountain range, trending southwest-northeast. Based on our fieldwork, seismic tomography images, seismicity, and previous studies, we propose an interpretation of the relationship between the surface deformation and fault kinematics in the study area and the internal dynamic processes acting in the Central Mediterranean from the Cenozoic to the present. The subduction and dynamics of internal forces beneath the complicated Maghrebides mobile belt have an impact on the Tertiary and Quaternary tectonic regimes in the Pelagian and Atlassic foreland that is part of our study region. The left lateral reactivation of the major "Tunisian N-S Axis fault" and the development of a compressional relay between the Hammamet Korbous and Messella-Ressas faults are possibly a result of tectonic stresses due to the slab roll-back following the Africa/Eurasia convergence. After the slab segmentation and its eastward migration (5–4 Ma) and the formation of the Strait of Sicily "rift zone" further east, a transtensional tectonic regime has been installed in this area. According to seismic tomography images, the STEP fault of the "North-South Axis" at Hammamet-Korbous coincides with the western edge of the "Slab windows" of the Sicilian Channel and the eastern boundary of the positive anomalies attributed to the residual Slab of Tunisia. On the other hand, significant E-W Plio-Quaternary tectonic activity may be observed along the eastern portion of this STEP fault system in the Grombalia zone as a result of recent vertical lithospheric motion in response to the lateral slab migration eastward to Sicily Channel. According to SKS fast splitting directions, the upper mantle flow pattern beneath Tunisian Dorsal is parallel to the NE-SW to E-W orientation of the Shmin identified in the study area, similar to the Plio-Quaternary extensional orientation in the Central Mediterranean. Additionally, the removal of the lithosphere and the subsequent uplift of the sub-lithospheric mantle beneath the topographic highs of the Dorsal and its surroundings may be the cause of the dominant extensional to transtensional Quaternary regime. The occurrence of strike-slip and extensional seismic events in the Pelagian block reveals that the regional transtensional tectonic regime persists today. Finally, we believe that the geodynamic history of the study area since the Cenozoic is primarily influenced by the preexisting weak zones, the African slab detachment, and the upper mantle flow pattern in the central Mediterranean.

Keywords: Tunisia, lithospheric discontinuity (STEP fault), geodynamic evolution, Tunisian dorsal backland, strike-slip fault, seismic tomography, seismicity, central Mediterranean

Procedia PDF Downloads 43

Authors: Meitham Amereh, Mohsen Akbari, Ben Nadler

Abstract:

Cancer has been recognized as one of the most challenging problems in biology and medicine. Aggressive tumors are a lethal type of cancers characterized by high genomic instability, rapid progression, invasiveness, and therapeutic resistance. Their behavior involves complicated molecular biology and consequential dynamics. Although tremendous effort has been devoted to developing therapeutic approaches, there is still a huge need for new insights into the dark aspects of tumors. As one of the key requirements in better understanding the complex behavior of tumors, mathematical modeling and continuum physics, in particular, play a pivotal role. Mathematical modeling can provide a quantitative prediction on biological processes and help interpret complicated physiological interactions in tumors microenvironment. The pathophysiology of aggressive tumors is strongly affected by the extracellular cues such as stresses produced by mechanical forces between the tumor and the host tissue. During the tumor progression, the growing mass displaces the surrounding extracellular matrix (ECM), and due to the level of tissue stiffness, stress accumulates inside the tumor. The produced stress can influence the tumor by breaking adherent junctions. During this process, the tumor stops the rapid proliferation and begins to remodel its shape to preserve the homeostatic equilibrium state. To reach this, the tumor, in turn, upregulates epithelial to mesenchymal transit-inducing transcription factors (EMT-TFs). These EMT-TFs are involved in various signaling cascades, which are often associated with tumor invasiveness and malignancy. In this work, we modeled the tumor as a growing hyperplastic mass and investigated the effects of mechanical stress from surrounding ECM on tumor invasion. The invasion is modeled as volume-preserving inelastic evolution. In this framework, principal balance laws are considered for tumor mass, linear momentum, and diffusion of nutrients. Also, mechanical interactions between the tumor and ECM is modeled using Ciarlet constitutive strain energy function, and dissipation inequality is utilized to model the volumetric growth rate. System parameters, such as rate of nutrient uptake and cell proliferation, are obtained experimentally. To validate the model, human Glioblastoma multiforme (hGBM) tumor spheroids were incorporated inside Matrigel/Alginate composite hydrogel and was injected into a microfluidic chip to mimic the tumor’s natural microenvironment. The invasion structure was analyzed by imaging the spheroid over time. Also, the expression of transcriptional factors involved in invasion was measured by immune-staining the tumor. The volumetric growth, stress distribution, and inelastic evolution of tumors were predicted by the model. Results showed that the level of invasion is in direct correlation with the level of predicted stress within the tumor. Moreover, the invasion length measured by fluorescent imaging was shown to be related to the inelastic evolution of tumors obtained by the model.

Keywords: cancer, invasion, mathematical modeling, microfluidic chip, tumor spheroids

Procedia PDF Downloads 87

Authors: Eiji Nakamachi, Tsuyoshi Eguchi, Sayo Yamamoto, Yusuke Morita, H. Sakamoto

Abstract:

In this study, we aim to reveal the relationship between the meniscal tearing and the articular cartilage injury of knee joint by using the dynamic explicit finite element (FE) method. Meniscal injuries reduce its functional ability and consequently increase the load on the articular cartilage of knee joint. In order to prevent the induction of osteoarthritis (OA) caused by meniscal injuries, many medical treatment techniques, such as artificial meniscus replacement and meniscal regeneration, have been developed. However, it is reported that these treatments are not the comprehensive methods. In order to reveal the fundamental mechanism of OA induction, the mechanical characterization of meniscus under the condition of normal and injured states is carried out by using FE analyses. At first, a FE model of the human knee joint in the case of normal state – ‘intact’ - was constructed by using the magnetron resonance (MR) tomography images and the image construction code, Materialize Mimics. Next, two types of meniscal injury models with the radial tears of medial and lateral menisci were constructed. In FE analyses, the linear elastic constitutive law was adopted for the femur and tibia bones, the visco-hyperelastic constitutive law for the articular cartilage, and the visco-anisotropic hyperelastic constitutive law for the meniscus, respectively. Material properties of articular cartilage and meniscus were identified using the stress-strain curves obtained by our compressive and the tensile tests. The numerical results under the normal walking condition revealed how and where the maximum compressive stress occurred on the articular cartilage. The maximum compressive stress and its occurrence point were varied in the intact and two meniscal tear models. These compressive stress values can be used to establish the threshold value to cause the pathological change for the diagnosis. In this study, FE analyses of knee joint were carried out to reveal the influence of meniscal injuries on the cartilage injury. The following conclusions are obtained. 1. 3D FE model, which consists femur, tibia, articular cartilage and meniscus was constructed based on MR images of human knee joint. The image processing code, Materialize Mimics was used by using the tetrahedral FE elements. 2. Visco-anisotropic hyperelastic constitutive equation was formulated by adopting the generalized Kelvin model. The material properties of meniscus and articular cartilage were determined by curve fitting with experimental results. 3. Stresses on the articular cartilage and menisci were obtained in cases of the intact and two radial tears of medial and lateral menisci. Through comparison with the case of intact knee joint, two tear models show almost same stress value and higher value than the intact one. It was shown that both meniscal tears induce the stress localization in both medial and lateral regions. It is confirmed that our newly developed FE analysis code has a potential to be a new diagnostic system to evaluate the meniscal damage on the articular cartilage through the mechanical functional assessment.

Keywords: finite element analysis, hyperelastic constitutive law, knee joint injury, meniscal tear, stress concentration

Procedia PDF Downloads 211