Search results for: kinematic and material coupling

Authors: O. Rahli, N. Mimouni, R. Bennacer, K. Bouhadef

Abstract:

This numerical study investigates the travelling wave’s appearance and the behavior of Poiseuille-Rayleigh-Benard (PRB) flow induced in 3D thermosolutale mixed convection (TSMC) in horizontal rectangular channels. The governing equations are discretized by using a control volume method with third order Quick scheme in approximating the advection terms. Simpler algorithm is used to handle coupling between the momentum and continuity equations. To avoid the excessively high computer time, full approximation storage (FAS) with full multigrid (FMG) method is used to solve the problem. For a broad range of dimensionless controlling parameters, the contribution of this work is to analyzing the flow regimes of the steady longitudinal thermoconvective rolls (noted R//) for both thermal and mass transfer (TSMC). The transition from the opposed volume forces to cooperating ones, considerably affects the birth and the development of the longitudinal rolls. The heat and mass transfers distribution are also examined.

Keywords: heat and mass transfer, mixed convection, poiseuille-rayleigh-benard flow, rectangular duct

Procedia PDF Downloads 298

Authors: Chejarla Raghunathababu, E. Logashanmugam

Abstract:

An antenna is an assortment of linked devices that function together to transmit and receive radio waves as a single antenna. Antennas occur in a variety of sizes and forms, but the microstrip patch antenna outperforms other types in terms of effectiveness and prediction. These antennas are easy to generate with discreet benefits. Nevertheless, the antenna's effectiveness will be affected because of the patch's shape above a thick dielectric substrate. As a result, a double-pole rectangular microstrip antenna with nanofillers was suggested in this study. By employing nano-composite substances (Fumed Silica and Aluminum Oxide), which are composites of graphene with nanofillers, the physical characteristics of the microstrip antenna, that is, the elevation of the microstrip antenna substrate and the width of the patch microstrip antenna have been improved in this research. The surface conductivity of graphene may be modified to function at specific frequencies. In order to prepare for future wireless communication technologies, a microstrip patch antenna operating at 93 GHz resonant frequency is constructed and investigated. The goal of this study was to reduce VSWR and increase gain. The simulation yielded results for the gain and VSWR, which were 8.26 dBi and 1.01, respectively.

Keywords: graphene, microstrip patch antenna, substrate material, wireless communication, nanocomposite material

Procedia PDF Downloads 111

Authors: Traore Papa Touty

Abstract:

This article presents a numerical method for determining the thermal conductivity of local materials, kapok plaster and tow plaster. It consists of heating the front face of a wall made from these two materials and at the same time insulating its rear face. We simultaneously study the curves of the evolution of the heat flux density as a function of time on the rear face and the evolution of the temperature gradient as a function of time between the heated face and the insulated face. Thermal conductivity is obtained when reaching a steady state when the evolution of the heat flux density and the temperature gradient no longer depend on time. The results showed that the theoretical value of thermal conductivity is obtained when the material has reached its equilibrium state. And the values obtained for different values of the convective exchange coefficients are appreciably equal to the experimental value.

Keywords: thermal conductivity, numerical method, heat exchange coefficient, transitional regime

Procedia PDF Downloads 219

Authors: Theo Ndereyimana, Yann Dufresne, Micael Boulet, Stephane Moreau

Abstract:

The DEM (Discrete Element Method) is used a lot in the industry to simulate large-scale flows of particles; for instance, in a fluidized bed, it allows to predict of the trajectory of every particle. One of the main limits of the DEM is the computational time. The CGM (Coarse-Graining Method) has been developed to tackle this issue. The goal is to increase the size of the particle and, by this means, decrease the number of particles. The method leads to a reduction of the collision frequency due to the reduction of the number of particles. Multiple characteristics of the particle movement and the fluid flow - when there is a coupling between DEM and CFD (Computational Fluid Dynamics). The main characteristic that is impacted is the energy dissipation of the system, to regain the dissipation, an ADM (Additional Dissipative Mechanism) can be added to the model. The objective of this current work is to observe the influence of the choice of the ADM and the factor of coarse-graining on the numerical results. These results will be compared with experimental results of a fluidized bed and with a numerical model of the same fluidized bed without using the CGM. The numerical model is one of a 3D cylindrical fluidized bed with 9.6M Geldart B-type particles in a bubbling regime.

Keywords: additive dissipative mechanism, coarse-graining, discrete element method, fluidized bed

Procedia PDF Downloads 70

Authors: Kornkanok Noulta, Pornsri Pakeyangkoon, Stephen T. Dubas, Pomthong Malakul, Manit Nithithanakul

Abstract:

In recent years, interest in the development of material for tissue engineering application has increased considerably. Poly(High Internal Phase Emulsion) (PolyHIPE) foam is a material that is good candidate for used in tissue engineering application due to its 3D structure and highly porous with interconnected pore. The PolyHIPE was prepared from poly (styrene/ethylene glycol dimethacrylate) through high internal phase emulsion polymerization technique and loaded with hydroxyapatite (HA) to improve biocompatibility. To further increase hydrophilicity of the obtained polyHIPE, layer-by-layer polyelectrolyte multilayers (PEM) technique was used. A surface property of polyHIPE was characterized by contact angle measurement. Morphology and pore size was observed by scanning electron microscope (SEM). The cell viability was revealed by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay technique.

Keywords: polyelectrolyte multilayer thin film, high internal phase emulsion, polyhipe foam, scaffold, tissue engineering

Procedia PDF Downloads 351

Authors: Jwan J. Abdullah, Greetham Darren, Gregory A, Tucker, Chenyu Du

Abstract:

Solid-state fermentation (SSF) is an alternative to liquid fermentations for the production of commercially important products such as antibiotics, single cell proteins, enzymes, organic acids, or biofuels from lignocellulosic material. This paper describes the optimisation of SSF on municipal solid waste (MSW) for the production of cellulase enzyme. Production of cellulase enzymes was optimised by Trichoderma reesei or Aspergillus niger for temperature, moisture content, inoculation, and period of incubation. Also, presence of minerals, and alternative carbon and nitrogen sources. Optimisation revealed that production of cellulolytic enzymes was optimal when using Trichoderma spp at 30°C with an incubation period of 168 hours with a 60% moisture content. Crude enzymes produced from MSW, by Trichoderma were evaluated for the saccharification of MSW and compared with activity of a commercially available enzyme, results demonstrated that MSW can be used as inexpensive lignocellulosic material for the production of cellulase enzymes using Trichoderma reesei.

Keywords: SSF, enzyme hydrolysis, municipal solid waste (MSW), optimizing conditions, enzyme hydrolysis

Procedia PDF Downloads 555

Authors: D. Gueribiz, F. Jacquemin, S. Fréour

Abstract:

During their service life, composite materials are submitted to humid environments. The moisture absorbed by their matrix polymer induced internal stresses which can lead to multi-scale damage and may reduce the lifetime of composite structures. The estimation of internal stresses is based at a first on realistic evaluation of the diffusive behavior of composite materials. Generally, the modeling and simulation of the diffusive behavior of composite materials are extensively investigated through decoupled models based on the assumption of Fickien behavior. For these approaches, the concentration and the deformation (or stresses), the two state variables of the problem considered are governed by independent equations which are solved separately. In this study, a model coupling diffusive behavior with stresses state for a polymer matrix composite reinforced with impermeable fibers is proposed, the investigation of diffusive behavior is based on a more general thermodynamic approach which introduces a dependence of diffusive behavior on internal stresses state. The coupled diffusive behavior modeling was established in first for homogeneous and isotropic matrix and it is, thereafter, extended to impermeable unidirectional composites.

Keywords: composites materials, moisture diffusion, effective moisture diffusivity, coupled moisture diffusion

Procedia PDF Downloads 308

Authors: Narendra Akhadkar, Silvestre Cano, Christophe Gourru

Abstract:

Injection-molded parts are widely used in power system protection products. One of the biggest challenges in an injection molding process is shrinkage and warpage of the molded parts. All these geometrical variations may have an adverse effect on the quality of the product, functionality, cost, and time-to-market. The situation becomes more challenging in the case of intricate shapes and in mass production using multi-cavity tools. To control the effects of shrinkage and warpage, it is very important to correctly find out the input parameters that could affect the product performance. With the advances in the computer-aided engineering (CAE), different tools are available to simulate the injection molding process. For our case study, we used the MoldFlow insight tool. Our aim is to predict the spread of the functional dimensions and geometrical variations on the part due to variations in the input parameters such as material viscosity, packing pressure, mold temperature, melt temperature, and injection speed. The input parameters may vary during batch production or due to variations in the machine process settings. To perform the accurate product assembly variation simulation, the first step is to perform an individual part variation simulation to render realistic tolerance ranges. In this article, we present a method to simulate part variations coming from the input parameters variation during batch production. The method is based on computer simulations and experimental validation using the full factorial design of experiments (DoE). The robustness of the simulation model is verified through input parameter wise sensitivity analysis study performed using simulations and experiments; all the results show a very good correlation in the material flow direction. There exists a non-linear interaction between material and the input process variables. It is observed that the parameters such as packing pressure, material, and mold temperature play an important role in spread on functional dimensions and geometrical variations. This method will allow us in the future to develop accurate/realistic virtual prototypes based on trusted simulated process variation and, therefore, increase the product quality and potentially decrease the time to market.

Keywords: correlation, molding process, tolerance, sensitivity analysis, variation simulation

Procedia PDF Downloads 178

Authors: Meltem Nur Erdöl, Feyzanur Bayrak, Elif Emanetçi, Faik Nüzhet Oktar, Cevriye Kalkandelen, Oğuzhan Gündüz

Abstract:

Nowadays, the bioceramic graft applications are very important due to the fact that especially European population is getting much older. Consequently, healing approaches for some health problems become more important in the near future. For instance, osteoporosis is one of the reasons for serious hip fractures. Beside these, the traffic accidents playing role increasing of various hip fractures and other bone fractures. Naturally all these are leading the importance developing new bioceramic graft materials. Hydroxyapatite (HA) is one of the leading bioceramics on the market. Beside the high biocompatibility HA bioceramics unfortunately are weak materials for loaded areas. For improvement mechanical properties of HA material, some oxides and metallic powders can be added. In this study, some rare earth oxides like hafnium (IV) oxide (HfO₂) and samarium (III) oxide (Sm₂O₃) are added to HA for improvement of their material characteristics. Thus, compression, microhardness and theoretical density tests are performed. X-ray diffraction patterns are also investigated corresponding x-ray diffraction equipment. At the end, studies of scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDX) are completed. All values were compared with past BHA and various composites.

Keywords: biocomposite, hafnium oxide, hydroxyapatite, nanotechnology, samarium oxide

Procedia PDF Downloads 174

Authors: Kumator Josiphiah Taku

Abstract:

Sustainability in construction is essential to the economic construction and can be achieved by the use of locally available construction materials. This research work, thus, uses locally available materials –calcined clay and Sandcrete SPR-300 superplasticizer in the production of Self Compacting Concrete (SCC) by investigating the correlation between the superplasticizer dosage and the fresh and hardened states properties of a grade 50 SCC made by incorporating a Calcined Clay (CC) – Portland Limestone Cement (PLC) blend as the cementitious matter at 20% replacement of PLC with CC and using CC as filler. The superplasticizer dosage was varied from 0.4 to 3.0% by weight of cementitious material and the slump, v-funnel, L-box and strength parameters investigated. The result shows a positive correlation between the increased dosage of the superplasticizer and the fresh and hardened states properties of the SCC up to 2% dosage. The J¬Spread¬, t¬500J¬, Slump flow, L-box H¬2¬/H¬1 ¬ratio and strength, all increases with SP dosage while the V-funnel flow decreased with SP dosage. Overall, SP ratio of 0.5 to 2.0 can be used in improving the properties of SCC produced using calcined clay both as filler and cementitious material.

Keywords: calcined clay, compressive strength, fresh-state properties of SCC, self compacting concrete, superplasticizer dosage

Procedia PDF Downloads 166

Authors: Flavia Laffleur, Andreas Bernkop-Schnürch

Abstract:

Purpose: This study was aimed to investigate preactivated thiomers for their mucoadhesive potential. Methods: Accordingly, chitosan-thioglycolic-mercaptonicotinamide conjugates (chitosan-TGA-MNA) were synthesized by the oxidative S-S coupling of chitosan-thioglycolic acid (chitosan-TGA) with 6-mercaptonicotin amide (MNA). Unmodified chitosan, chitosan-TGA (thiomers) and chitosan-TGA-MNA conjugates were compressed into test discs to investigate cohesive properties, cytotoxicity assays and mucoadhesion studies. Results: Due to the immobilization of MNA, the chitosan-TGA-MNA conjugates exhibit comparatively higher swelling properties and cohesive properties corresponding unmodified chitosan. On the rotating cylinder, discs based on chitosan-TGA-MNA conjugates displayed 3.1-fold improved mucoadhesion time compared to thiolated polymers. Tensile study results were found in good agreement with rotating cylinder results. Moreover, preactivated thiomers showed higher stability. All polymers were found non-toxic over Caco-2 cells. Conclusion: On the basis of achieved results the pre activated thiomeric therapeutic agent seems to represent a promising generation of mucoadhesive polymers which are safe to use for a prolonged residence time to target the mucosa.

Keywords: biomedical application, drug delivery, polymer, thiomer

Procedia PDF Downloads 434

Authors: Ahmed M. Ashteyat

Abstract:

Artificial Neural Network (ANN) models have been widely used in material modeling, inter-correlations, as well as behavior and trend predictions when the nonlinear relationship between system parameters cannot be quantified explicitly and mathematically. In this paper, ANN was used to predict the residual modulus of elasticity (RME) of self compacted concrete (SCC) damaged by heat. The ANN model was built, trained, tested and validated using a total of 112 experimental data sets, gathered from available literature. The data used in model development included temperature, relative humidity conditions, mix proportions, filler types, and fiber type. The result of ANN training, testing, and validation indicated that the RME of SCC, exposed to different temperature and relative humidity levels, could be predicted accurately with ANN techniques. The reliability between the predicated outputs and the actual experimental data was 99%. This show that ANN has strong potential as a feasible tool for predicting residual elastic modulus of SCC damaged by heat within the range of input parameter. The ANN model could be used to estimate the RME of SCC, as a rapid inexpensive substitute for the much more complicated and time consuming direct measurement of the RME of SCC.

Keywords: residual modulus of elasticity, artificial neural networks, self compacted-concrete, material modeling

Procedia PDF Downloads 534

Authors: Koosha Rezaei, Mehdi Moghri bidgoli, Mazyar Khakpour

Abstract:

Wood-plastic composites foam is one of the most used products were the industry today. In this study, composite foam polypropylene in the presence of different biofilers such as Spruce wood, wheat and rice husk as well as 3 different types toughening agents such as polyolefin elastomer, styrene butadiene styrene and styrene-ethylene butadiene styrene, and two types of cause blowing agents azodicarbonamide and sodium bicarbonate was prepared. For improving dispersion of biofilers, in the mixing process we used polypropylene coupling agent grafted with maleic anhydride. Due to the large number of variables, the statistical analysis of response surface to analyze the results of the impact test, tensile modulus and tensile strength and modeling were used. Co-rotating twine extruder was made composite melt mixing method and then to perform mechanical tests using injection molding, respectively.Images from electron microscopy showed cell sandwich structure in composite amply demonstrates.

Keywords: polypropylene, wood plastic composite foam, response surface analysis, morphology, mechanical properties

Procedia PDF Downloads 365

Authors: Takeyuki Suzuki, Ismiyarto, Da-Yang Zhou, Kaori Asano, Hiroaki Sasai

Abstract:

The development of catalytic asymmetric reaction is important for the synthesis of natural products. To construct the multiple stereogenic centers, the desymmetrization of meso compounds is powerful strategy for the synthesis of chiral molecules. Oxidative desymmetrization of meso diols using chiral iridium catalyst provides a chiral hydroxyl ketone. The reaction is practical and an environmentally benign method which does not require the use of stoichiometric amount of heavy metals. This time we report here catalytic asymmetric synthesis of catalponol based on tandem coupling of meso-diols and an aldehyde. The tandem reaction includes oxidative desymmetrization of meso-diols, aldol condensation with an aldehyde. The reaction of meso-diol, benzaldehyde in the presence of a catalytic amount of chiral Ir complex and CsOH in tetrahydrofuran afforded the desired benzylidene ketone in 82% yield with 96% ee (enantiomeric excess). Next, we applied this benzylidene ketone derivative to the synthesis of catalponol. The corresponding benzylidene ketone was obtained in 87% yield with 99% ee. Finally, catalponol was synthesized by the regio- and stereo-selective reduction of dienone moiety in good yield.

Keywords: catalponol, desymmetrization, iridium, oxidation

Procedia PDF Downloads 171

Authors: Makhlouf Mourad, Messabih Sidi Mohamed, Bouchher Omar, Houali Farida, Benrachedi Khaled

Abstract:

Mesoporous materials are very commonly used as adsorbent materials for removing phenolic compounds. However, the adsorption mechanism of these compounds is still poorly controlled. However, understanding the interactions mesoporous materials/adsorbed molecules is very important in order to optimize the processes of liquid phase adsorption. The difficulty of synthesis is to keep an orderly and cubic pore structure and achieve a homogeneous surface modification. The grafting of Si(CH₃)₃ was chosen, to transform hydrophilic surfaces hydrophobic surfaces. The aim of this work is to study the kinetics and thermodynamics of two volatile organic compounds VOC phenol (PhOH) and P hydroxy benzoic acid (4AHB) on a mesoporous material of type MCM-48 grafted with an organosilane of the Trimethylchlorosilane (TMCS) type, the material thus grafted or functionalized (hereinafter referred to as MCM-48-G). In a first step, the kinetic and thermodynamic study of the adsorption isotherms of each of the VOCs in mono-solution was carried out. In a second step, a similar study was carried out on a mixture of these two compounds. Kinetic models (pseudo-first order, pseudo-second order) were used to determine kinetic adsorption parameters. The thermodynamic parameters of the adsorption isotherms were determined by the adsorption models (Langmuir, Freundlich). The comparative study of adsorption of PhOH and 4AHB proved that MCM-48-G had a high adsorption capacity for PhOH and 4AHB; this may be related to the hydrophobicity created by the organic function of TMCS in MCM-48-G. The adsorption results for the two compounds using the Freundlich and Langmuir models show that the adsorption of 4AHB was higher than PhOH. The values ​​obtained by the adsorption thermodynamics show that the adsorption interactions for our sample with the phenol and 4AHB are of a physical nature. The adsorption of our VOCs on the MCM-48 (G) is a spontaneous and exothermic process.

Keywords: adsorption, kinetics, isotherm, mesoporous materials, Phenol, P-hydroxy benzoique acid

Procedia PDF Downloads 208

Authors: M. L. W. P. De Silva, R. A. C. Rabel, N. Smith, L. McIntyre, T. J Parkinson, K. A. N. Wijayawardhane

Abstract:

Curricular integration is an important concept in medical education for developing students’ ability to create connections between different medical disciplines. Problem-Based Learning (PBL) is one of the vehicles through which such integration can be achieved. During the recent review of the veterinary curriculum at the University of Peradeniya, a series of courses in Integrative Veterinary Science (IVS) were introduced, in which PBL was the primary teaching methodology. The objectives of this study were to evaluate students’ opinions on PBL as a teaching method: it should be noted that, within the context of secondary and tertiary education in Sri Lanka, this would be an entirely novel learning experience for the students. Opinions were sought at the conclusion of IVS sessions where students of semesters 2, 4, 6, and 7 (of an 8-semester program) were exposed to a two, 2-hour PBL-based case scenario. The PBL-based case scenario in semesters 2, 4, and 7 were delivered using material previously developed by an experienced PBL practitioner, whilst material for semester 6 was prepared de novo by a less experienced practitioner. Each student (semesters 2: n=38, 4: n=37, 6: n=55, and 7: n=40) completed a questionnaire which asked whether: (i) the course had improved their critical thinking skills; (ii) the learning environment was sufficiently comfortable to express/share student’s opinion; (iii) there was sufficient facilitator guidance; (iv) the online study environment enhanced learning; and (v) the students were overall satisfied with the PBL approach and IVS concept. Responses were given on a 5-point Likert-scale (strongly agree (SA), agree (A), neutral (N), disagree (D), and strongly disagree (SD)). SA and A responses were summed to provide an overall ‘satisfactory’ response. Results were subjected to frequency-distribution statistical analysis. A total of 88.5% of students gave SA+A scores to their overall satisfaction. The proportion of SA+A scores differed between different semesters, such that 95% of semester 2, 4, and 7 students gave SA+A scores, whereas only 69% of semester 6 students did so for their respective sessions. Overall, 96% of the students gave SA+A scores to the question relating to the improvement of critical thinking skills: semester 6 students’ scores were marginally, but not significantly, lower (91% SA+A) than those in other semesters. The difference of scores between semester 6 and the other semesters may be attributed to the different PBL-material used and/or the different experience levels of the practitioners that developed the study material. The use of PBL as a means of teaching IVS curriculum-integration courses was well-received by the students in terms of their overall satisfaction and their perceptions of improved critical thinking skills. Importantly, this was achieved in the face of a methodology that was entirely novel to the students. Finally, the delivery of the PBL medium was readily mastered by the practitioner to whom it was also a novel methodology.

Keywords: critical thinking skills, integration, problem based learning, veterinary education

Procedia PDF Downloads 133

Authors: Delva Richard, Zahibo Narcisse, Yalciner Ahmet

Abstract:

The Republic of Haiti is one of the poor countries of the world, therefore the authorities must make choices to provide timely solutions to the many difficulties that this Caribbean country is experiencing. There is a very acute lack of scientific research to study natural phenomena in depth. A working group meeting was established under the aegis of the World Bank, UNESCO and the authorities, to study the level of exposure of the Hispaniola. The devastating earthquake of August 2021 killed about 2100 and caused massive material damage; and the 14 12 January 2010 killed more than 250,000 people and caused massive material damage, the evidence of which is still 11 years later. In this paper we want to contribute to the assessment of the risk of tsunami on the southern peninsula of the Republic of Haiti. For the realization of this work we have the bathymetric and topographic data of very good qualities from the private measurement campaigns that we have combined with GEBCO for the inundation grids. We use two numerical models MOST and NAMI DANCE for the calculation of the parameters required in any tsunami risk assessment.

Keywords: modélisation numérique, ondes longues océaniques, bathymetrie, evaluation risque, tsunamis

Procedia PDF Downloads 7

Authors: R. M. Shabbir Ahmed, Mohamed Haneef, A. R. Anwar Khan

Abstract:

Analysis of stresses plays important role in the optimization of structures. Prior stress estimation helps in better design of the products. Composites find wide usage in the industrial and home applications due to its strength to weight ratio. Especially in the air craft industry, the usage of composites is more due to its advantages over the conventional materials. Composites are mainly made of orthotropic materials having unequal strength in the different directions. Composite materials have the drawback of delamination and debonding due to the weaker bond materials compared to the parent materials. So proper analysis should be done to the composite joints before using it in the practical conditions. In the present work, a composite plate with elastic pin is considered for analysis using finite element software Ansys. Basically the geometry is built using Ansys software using top down approach with different Boolean operations. The modelled object is meshed with three dimensional layered element solid46 for composite plate and solid element (Solid45) for pin material. Various combinations are considered to find the strength of the composite joint under uniaxial loading conditions. Due to symmetry of the problem, only quarter geometry is built and results are presented for full model using Ansys expansion options. The results show effect of pin diameter on the joint strength. Here the deflection and load sharing of the pin are increasing and other parameters like overall stress, pin stress and contact pressure are reducing due to lesser load on the plate material. Further material effect shows, higher young modulus material has little deflection, but other parameters are increasing. Interference analysis shows increasing of overall stress, pin stress, contact stress along with pin bearing load. This increase should be understood properly for increasing the load carrying capacity of the joint. Generally every structure is preloaded to increase the compressive stress in the joint to increase the load carrying capacity. But the stress increase should be properly analysed for composite due to its delamination and debonding effects due to failure of the bond materials. When results for an isotropic combination is compared with composite joint, isotropic joint shows uniformity of the results with lesser values for all parameters. This is mainly due to applied layer angle combinations. All the results are represented with necessasary pictorial plots.

Keywords: bearing force, frictional force, finite element analysis, ANSYS

Procedia PDF Downloads 334

Authors: M. C. A. Leite, B. Chen-Charpentier, F. Agusto

Abstract:

A long-term goal of sustainable forest management is a relatively stable source of wood and a stable forest age-class structure has become the goal of many forest management practices. In the absence of disturbances, this forest management goal could easily be achieved. However, in the face of recurring insect outbreaks and other disruptive processes forest planning becomes more difficult, requiring knowledge of the effects on the forest of a wide variety of environmental factors (e.g., habitat heterogeneity, fire size and frequency, harvesting, insect outbreaks, and age distributions). The association between distinct forest disturbances and the potential effect on forest dynamics is a complex matter, particularly when evaluated over time and at large scale, and is not well understood. However, gaining knowledge in this area is crucial for a sustainable forest management. Mathematical modeling is a tool that can be used to broader the understanding in this area. In this talk we will introduce mathematical models formulation incorporating the effect of insect outbreaks either as a single disturbance in the forest population dynamics or coupled with other disturbances: either wildfire or harvesting. The results and ecological insights will be discussed.

Keywords: age-structured forest population, disturbances interaction, harvesting insects outbreak dynamics, mathematical modeling

Procedia PDF Downloads 525

Authors: David Alejandro Lazo-Vasquez, Jorge Luis Balino

Abstract:

In the petroleum industry, multiphase flow occurs when oil, gas, and water are transported in the same pipe through large pipeline systems. The flow can take different patterns depending on parameters like fluid velocities, pipe diameter, pipe inclination, and fluid properties. Mainly, intermittent flow is produced by the natural propagation of short and long waves, according to the Kelvin-Helmholtz Stability Theory. To model stratified flow and the onset of intermittent flow, it is crucial to have knowledge of short and long waves behavior. The two-fluid model, frequently employed for characterizing multiphase systems, becomes ill-posed for high liquid and gas velocities and large inclination angles, for short waves can develop infinite growth rates. We are interested in focusing attention on long-wave instability, which leads to the production of roll waves that may grow and result in the transition from stratified flow to intermittent flow. In this study, global and local linear stability analyses for dynamic and kinematic stability criteria predict the regions of stability of the flow for different pipe inclinations and fluid velocities in regularized and non-regularized systems, concurrently. It was possible to distinguish when: wave growth rates are absolutely bounded (stable stratified smooth flow), waves have finite growth rates (unstable stratified wavy flow), and when the equation system becomes elliptic and hyperbolization is needed. In order to bound short wave growth rates and regularize the equation system, we incorporated some lower and higher-order terms like interfacial drag and surface tension, respectively.

Keywords: linear stability analysis, multiphase flow, onset of slugging, two-fluid model regularization

Procedia PDF Downloads 135

Authors: Vahid Ramezankhani, Keith J. Stevenson, Stanislav. S. Fedotov

Abstract:

Lithium-ion batteries (LIBs) play a pivotal role in achieving the key objective “zero-carbon emission” as countries agreed to reach a 1.5ᵒC global warming target according to the Paris agreement. Nowadays, due to the tremendous mobile and stationary consumption of small/large-format LIBs, the demand and consequently the price for such energy storage devices have been raised. The aforementioned challenges originate from the shrinkage of the major applied critical materials in these batteries, such as cobalt (Co), nickel (Ni), Lithium (Li), graphite (G), and manganese (Mn). Therefore, it is imperative to consider alternative elements to address issues corresponding to the limitation of resources around the globe. Potassium (K) is considered an effective alternative to Li since K is a more abundant element, has a higher operating potential, a faster diffusion rate, and the lowest stokes radius in comparison to the closest neighbors in the periodic table (Li and Na). Among all reported materials for metal-ion batteries, some of them possess the general formula AMXO4L [A = Li, Na, K; M = Fe, Ti, V; X = P, S, Si; L= O, F, OH] is of potential to be applied both as anode and cathode and enable researchers to investigate them in the full symmetric battery format. KTiPO4F (KTP structural material) has been previously reported by our group as a promising cathode with decent electronic properties. Herein, we report a synthesis, crystal structure characterization, morphology, as well as K-ion storage properties of KTiPO4F. Our investigation reveals that KTiPO4F delivers discharge capacity > 150 mAh/g at 26.6 mA/g (C/5 current rate) in the potential window of 0.001-3 V. Surprisingly, the cycling performance of C-KTiPO4F//K cell is stable for 1000 cycles at 130 mA/g (C current rate), presenting capacity > 130 mAh/g. More interestingly, we achieved to assemble full symmetric batteries where carbon-coated KTiPO4F serves as both negative and positive electrodes, delivering >70 mAh/g in the potential range of 0.001-4.2V.

Keywords: anode material, potassium battery, chemical characterization, electrochemical properties

Procedia PDF Downloads 220

Authors: Ella C. Linganiso, Bonex W. Mwakikunga, Trilock Singh, Sanjay Mathur, Odireleng M. Ntwaeaborwa

Abstract:

The use of nanostructured semiconducting material to catalyze degradation of environmental pollutants still receives much attention to date. One of the desired characteristics for pollutant degradation under ultra-violet visible light is the materials with extended carrier charge separation that allows for electronic transfer between the catalyst and the pollutants. In this work, zinc oxide n-type semiconductor vertically aligned structures were fabricated on silicon (100) substrates using the chemical bath deposition method. The as-synthesized structures were treated with nickel and sulphur. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy were used to characterize the phase purity, structural dimensions and elemental composition of the obtained structures respectively. Photoluminescence emission measurements showed a decrease in both the near band edge emission as well as the defect band emission upon addition of nickel and sulphur with different concentrations. This was attributed to increased charger-carrier-separation due to the presence of Ni-S material on ZnO surface, which is linked to improved charge transfer during photocatalytic reactions.

Keywords: Carrier-charge-separation, nickel, photoluminescence, sulphur, zinc oxide

Procedia PDF Downloads 308

Authors: Farah Benbouabdellah

Abstract:

This research examines the shifting portrayal of tigers in visual media, particularly cinema, to explore how cultural, political, and ecological perspectives influence animal symbolism. Through an interdisciplinary approach combining film studies, anthropology, art history, and material culture, this study investigates tiger representations in static and moving images, from early art forms to 20th-century films. The research highlights how the film has perpetuated, transformed, and politicised tiger imagery across contexts by analysing colonialism, identity, and ecological change themes. With a comprehensive focus on Indian and Western cinema, this study illustrates the tiger's enduring role as a cultural symbol and its impact on visual narratives, exploring techniques in cinematography, audience reception, and narratives that helped shape the animal's iconic status. This research aims to provide a comprehensive view of tiger representations in media, addressing the intersection of animal symbolism and sociocultural values across historical and regional landscapes.

Keywords: tiger representation, visual media, anthropology media, material culture, film studies, comparative analysis

Procedia PDF Downloads 8

Authors: Bolatbek Rysbaiuly, Nazerke Rysbayeva, Aigerim Rysbayeva

Abstract:

Relevance: Energy saving elevated to public policy in almost all developed countries. One of the areas for energy efficiency is improving and tightening design standards. In the tie with the state standards, make high demands for thermal protection of buildings. Constructive arrangement of layers should ensure normal operation in which the humidity of materials of construction should not exceed a certain level. Elevated levels of moisture in the walls can be attributed to a defective condition, as moisture significantly reduces the physical, mechanical and thermal properties of materials. Absence at the design stage of modeling the processes occurring in the construction and predict the behavior of structures during their work in the real world leads to an increase in heat loss and premature aging structures. Method: To solve this problem, widely used method of mathematical modeling of heat and mass transfer in materials. The mathematical modeling of heat and mass transfer are taken into the equation interconnected layer [1]. In winter, the thermal and hydraulic conductivity characteristics of the materials are nonlinear and depends on the temperature and moisture in the material. In this case, the experimental method of determining the coefficient of the freezing or thawing of the material becomes much more difficult. Therefore, in this paper we propose an approximate method for calculating the thermal conductivity and moisture permeability characteristics of freezing or thawing material. Questions. Following the development of methods for solving the inverse problem of mathematical modeling allows us to answer questions that are closely related to the rational design of fences: Where the zone of condensation in the body of the multi-layer fencing; How and where to apply insulation rationally his place; Any constructive activities necessary to provide for the removal of moisture from the structure; What should be the temperature and humidity conditions for the normal operation of the premises enclosing structure; What is the longevity of the structure in terms of its components frost materials. Tasks: The proposed mathematical model to solve the following problems: To assess the condition of the thermo-physical designed structures at different operating conditions and select appropriate material layers; Calculate the temperature field in a structurally complex multilayer structures; When measuring temperature and moisture in the characteristic points to determine the thermal characteristics of the materials constituting the surveyed construction; Laboratory testing to significantly reduce test time, and eliminates the climatic chamber and expensive instrumentation experiments and research; Allows you to simulate real-life situations that arise in multilayer enclosing structures associated with freezing, thawing, drying and cooling of any layer of the building material.

Keywords: energy saving, inverse problem, heat transfer, multilayer walling

Procedia PDF Downloads 397

Authors: Ajit Rai, Hamza Deroui, Blandine Vacher, Khwansiri Ninpan, Arthur Aumont, Francesco Vitillo, Robert Plana

Abstract:

Large-scale critical industrial scheduling problems are based on Resource-Constrained Project Scheduling Problems (RCPSP), that necessitate integration with other optimization problems (e.g., vehicle routing, supply chain, or unique industrial ones), thus requiring practical solutions (i.e., modular, computationally efficient with feasible solutions). To the best of our knowledge, the current industrial state of the art is not addressing this holistic problem. We propose an original modular solution that answers the issues exhibited by the delivery of complex projects. With three interlinked entities (project, task, resources) having their constraints, it uses a greedy heuristic with a dynamic cost function for each task with a situational assessment at each time step. It handles large-scale data and can be easily integrated with other optimization problems, already existing industrial tools and unique constraints as required by the use case. The solution has been tested and validated by domain experts on three use cases: outage management in Nuclear Power Plants (NPPs), planning of future NPP maintenance operation, and application in the defense industry on supply chain and factory relocation. In the first use case, the solution, in addition to the resources’ availability and tasks’ logical relationships, also integrates several project-specific constraints for outage management, like, handling of resource incompatibility, updating of tasks priorities, pausing tasks in a specific circumstance, and adjusting dynamic unit of resources. With more than 20,000 tasks and multiple constraints, the solution provides a feasible schedule within 10-15 minutes on a standard computer device. This time-effective simulation corresponds with the nature of the problem and requirements of several scenarios (30-40 simulations) before finalizing the schedules. The second use case is a factory relocation project where production lines must be moved to a new site while ensuring the continuity of their production. This generates the challenge of merging job shop scheduling and the RCPSP with location constraints. Our solution allows the automation of the production tasks while considering the rate expectation. The simulation algorithm manages the use and movement of resources and products to respect a given relocation scenario. The last use case establishes a future maintenance operation in an NPP. The project contains complex and hard constraints, like on Finish-Start precedence relationship (i.e., successor tasks have to start immediately after predecessors while respecting all constraints), shareable coactivity for managing workspaces, and requirements of a specific state of "cyclic" resources (they can have multiple states possible with only one at a time) to perform tasks (can require unique combinations of several cyclic resources). Our solution satisfies the requirement of minimization of the state changes of cyclic resources coupled with the makespan minimization. It offers a solution of 80 cyclic resources with 50 incompatibilities between levels in less than a minute. Conclusively, we propose a fast and feasible modular approach to various industrial scheduling problems that were validated by domain experts and compatible with existing industrial tools. This approach can be further enhanced by the use of machine learning techniques on historically repeated tasks to gain further insights for delay risk mitigation measures.

Keywords: deterministic scheduling, optimization coupling, modular scheduling, RCPSP

Procedia PDF Downloads 200

Authors: Ramish, Farhan Khalique Awan

Abstract:

Kinematic redundancy within the manipulators presents extended dexterity and manipulability to the manipulators. Redundant serial robotic manipulators are very popular in industries due to its competencies to keep away from singularities during normal operation and fault tolerance because of failure of one or more joints. Such fault tolerant manipulators are extraordinarily beneficial in applications where human interference for repair and overhaul is both impossible or tough; like in case of robotic arms for space programs, nuclear applications and so on. The design of this sort of fault tolerant serial 3 DoF manipulator is presented in this paper. This work was the extension of the author’s previous work of designing the simple 3R serial manipulator. This work is the realization of the previous design with optimizing the link lengths for incorporating the feature of fault tolerance. Various measures have been followed by the researchers to quantify the fault tolerance of such redundant manipulators. The fault tolerance in this work has been described in terms of the worst-case measure of relative manipulability that is, in fact, a local measure of optimization that works properly for certain configuration of the manipulators. An optimum fault tolerant Jacobian matrix has been determined first based on prescribed null space properties after which the link parameters have been described to meet the given Jacobian matrix. A solid model of the manipulator was then developed to realize the mathematically rigorous design. Further work was executed on determining the dynamic properties of the fault tolerant design and simulations of the movement for various trajectories have been carried out to evaluate the joint torques. The mathematical model of the system was derived via the Euler-Lagrange approach after which the same has been tested using the RoboAnalyzer© software. The results have been quite in agreement. From the CAD model and dynamic simulation data, the manipulator was fabricated in the workshop and Advanced Machining lab of NED University of Engineering and Technology.

Keywords: fault tolerant, Graham matrix, Jacobian, kinematics, Lagrange-Euler

Procedia PDF Downloads 222

Authors: Leonard Chimaobi Agim, Charles Arinzechukwu Igwe, Emmanuel Uzoma Onweremadu, Gabreil Osuji

Abstract:

Soil erosion has been linked to stream sedimentation, ecosystem degradation, and loss of soil nutrients. A study was conducted to evaluate the effect of some organic amendment on sediment yield, splash loss, and runoff of soils of selected parent materials in southeastern Nigeria. A total of 20 locations, five from each of four parent materials namely: Asu River Group (ARG), Bende Ameki Group (BAG), Coastal Plain Sand (CPS) and Falsebedded Sandstone (FBS) were used for the study. Collected soil samples were analyzed with standard methods for the initial soil properties. Rainfall simulation at an intensity of 190 mm hr-1was conducted for 30 minutes on the soil samples at both the initial stage and after amendment to obtain erosion parameters. The influence of parent material on sediment yield, splash loss and runoff based on rainfall simulation was tested for using one way analyses of variance, while the influence of organic material and their combinations were a factorially fitted in a randomized complete block design. The organic amendments include; goat dropping (GD), poultry dropping (PD), municipal solid waste (MSW) and their combinations (COA) applied at four rates of 0, 10, 20 and 30 t ha-1 respectively. Data were analyzed using analyses of variance suitable for a factorial experiment. Significant means were separated using LSD at 5 % probability levels. Result showed significant (p ≤ 0.05) lower values of sediment yield, splash loss and runoff following amendment. For instance, organic amendment reduced sediment yield under wet and dry runs by 12.91 % and 26.16% in Ishiagu, 40.76% and 45.67%, in Bende, 16.17% and 50% in Obinze and 22.80% and 42.35% in Umulolo respectively. Goat dropping and combination of amendment gave the best results in reducing sediment yield.

Keywords: organic amendment, parent material, rainfall simulation, soil erosion

Procedia PDF Downloads 343

Authors: D. M. Eric, D. Milosevic, F. D. Eric

Abstract:

Concurrent engineering technologies are a modern concept in manufacturing engineering. One of the key goals in designing modern technological processes is further reduction of production costs, both in the prototype and the preparatory part, as well as during the serial production. Thanks to many segments of concurrent engineering, these goals can be accomplished much more easily. In this paper, we give an overview of the advantages of using modern software simulations in relation to the classical aspects of designing technological processes of metal deformation. Significant savings are achieved thanks to the electronic simulation and software detection of all possible irregularities in the functional-working regime of the technological process. In order for the expected results to be optimal, it is necessary that the input parameters are very objective and that they reliably represent the values ​of these parameters in real conditions. Since it is a metal deformation treatment here, the particularly important parameters are the coefficient of internal friction between the working material and the tools, as well as the parameters related to the flow curve of the processing material. The paper will give a presentation for the experimental determination of some of these parameters.

Keywords: production technologies, metal processing, software simulations, effects of application

Procedia PDF Downloads 235

Authors: Pravat Ranjan Pati, Alok Satapathy

Abstract:

Linz-Donawitz (LD) slag a major solid waste generated in huge quantities during steel making. It comes from slag formers such as burned lime/dolomite and from oxidizing of silica, iron etc. while refining the iron into steel in the LD furnace. Although a number of ways for its utilization have been suggested, its potential as a filler material in polymeric matrices has not yet been explored. The present work reports the possible use of this waste in glass fiber reinforced epoxy composites as a filler material. Hybrid composites consisting of bi-directional e-glass-fiber reinforced epoxy filled with different LD slag content (0, 7.5, 15, 22.5 wt%) are prepared by simple hand lay-up technique. The composites are characterized in regard to their density, porosity, micro-hardness and strength properties. X-ray diffractography is carried out in order to ascertain the various phases present in LDS. This work shows that LD slag, in spite of being a waste, possesses fairly good filler characteristics as it modifies the strength properties and improves the composite micro-hardness of the polymeric resin.

Keywords: characterization, glass-epoxy composites, LD slag, waste utilization

Procedia PDF Downloads 392

Authors: Olga Shuvaeva, Tamara Romanova, Sergey Volynkin, Valentina Podolinnaya

Abstract:

Green chemistry concept is focused on the prevention of environmental pollution caused by human activity. However, there are a lot of contaminated areas in the world which pose a serious threat to ecosystems in terms of their conservation. Therefore in accordance with the principles of green chemistry, it should not be forgotten about the need to clean these areas. Furthermore, the waste material often contains the valuable components, the extraction of which by traditional wet chemical technologies is inefficient both from the economic and environmental protection standpoint. Wherein, the plants may be successfully used to ‘scavenge’ a range of metals from polluted land sites in an approach allowing to carry out both of these processes – phytoremediation and phytomining in conjunction. The goal of the present work was to study bioaccumulation ability of floating macrophytes such as water hyacinth and pondweed toward Hg, Ba, Cd, Mo and Pb as pollutants in aquatic medium and terrestrial plants (birch, reed, and cane) towards gold and silver as valuable components. The peculiarity of ongoing research was that the plants grew under extreme conditions (pH of drainage and pore waters was about 2.5). The study was conducted at the territory of Ursk tailings (Southwestern Siberia, Russia) formed as a result of primary polymetallic ores cyanidation. The waste material is mainly presented (~80%) by pyrite (FeS₂) and barite (BaSO₄), the raw minerals included FeAsS, HgS, PbS, Ag₂S as minor ones. It has been shown that water hyacinth demonstrates high ability to accumulate different metals, and what is especially important – to remove mercury from polluted waters with BCF value more than 1000. As for the gold, its concentrations in reed and cane growing near the waste material were estimated as 500 and 900 μg∙kg⁻¹ respectively. It was also found that the plants can survive under extreme conditions of acidic environment and hence we can assume that there is a principal opportunity to use them for the valuable substances extraction from an area of the mining waste dumps burial.

Keywords: bioaccumulation, gold, heavy metals, mine tailing

Procedia PDF Downloads 171