Search results for: driving forces

Authors: Ebrahim Ghasemi Ardi, Ai Bing Yu, Run Yu Yang

Abstract:

Current study is aimed to develop an available in-house discrete element method (DEM) code and link it with direct breakage event. So, it became possible to determine the particle breakage and then its fragments size distribution, simultaneous with DEM simulation. It directly applies the particle breakage inside the DEM computation algorithm and if any breakage happens the original particle is replaced with daughters. In this way, the calculation will be followed based on a new updated particles list which is very similar to the real grinding environment. To validate developed model, a grinding ball impacting an unconfined particle bed was simulated. Since considering an entire ball mill would be too computationally demanding, this method provided a simplified environment to test the model. Accordingly, a representative volume of the ball mill was simulated inside a box, which could emulate media (ball)–powder bed impacts in a ball mill and during particle bed impact tests. Mono, binary and ternary particle beds were simulated to determine the effects of granular composition on breakage kinetics. The results obtained from the DEM simulations showed a reduction in the specific breakage rate for coarse particles in binary mixtures. The origin of this phenomenon, commonly known as cushioning or decelerated breakage in dry milling processes, was explained by the DEM simulations. Fine particles in a particle bed increase mechanical energy loss, and reduce and distribute interparticle forces thereby inhibiting the breakage of the coarse component. On the other hand, the specific breakage rate of fine particles increased due to contacts associated with coarse particles. Such phenomenon, known as acceleration, was shown to be less significant, but should be considered in future attempts to accurately quantify non-linear breakage kinetics in the modeling of dry milling processes.

Keywords: particle bed, breakage models, breakage kinetic, discrete element method

Procedia PDF Downloads 166

Authors: Mohammed Islam, Jungyong Wang, Dong Cheol Seo

Abstract:

The Smoothed Particle Hydrodynamics (SPH) method is a novel, meshless, and Lagrangian technique based numerical method that has shown promises to accurately predict the hydrodynamics of water and structure interactions in violent flow conditions. The main goal of this study is to build confidence on the versatility of the Smoothed Particle Hydrodynamics (SPH) based tool, to use it as a complementary tool to the physical model testing capabilities and support research need for the performance evaluation of ships and offshore platforms exposed to an extreme and harsh environment. In the current endeavor, an open-sourced SPH-based tool was used and validated for modeling and predictions of the hydrodynamic interactions of a 6-DOF ship and bergy bits. The study involved the modeling of a modern generic drillship and simplified bergy bits in floating and towing scenarios and in regular and irregular wave conditions. The predictions were validated using the model-scale measurements on a moored ship towed at multiple oblique angles approaching a floating bergy bit in waves. Overall, this study results in a thorough comparison between the model scale measurements and the prediction outcomes from the SPH tool for performance and accuracy. The SPH predicted ship motions and forces were primarily within ±5% of the measurements. The velocity and pressure distribution and wave characteristics over the free surface depicts realistic interactions of the wave, ship, and the bergy bit. This work identifies and presents several challenges in preparing the input file, particularly while defining the mass properties of complex geometry, the computational requirements, and the post-processing of the outcomes.

Keywords: SPH, ship and bergy bit, hydrodynamic interactions, model validation, physical model testing

Procedia PDF Downloads 109

Authors: Aysel Mehdiyeva

Abstract:

As a driving force of society, the role of teachers is important in inspiring, motivating, and encouraging the younger generation to protect the environment. In light of these, the study aims to explore teachers’ beliefs to understand teachers’ engagement with teaching about the environment. Though teachers’ beliefs about the environment have been explored by a number of researchers, the influence of these beliefs in their professional lives and in shaping their classroom instructions has not been widely investigated in Azerbaijan. To this end, this study aims to reveal the beliefs of secondary school geography teachers about the environment and find out the ways teachers’ beliefs of the environment are enacted in their classroom practice in Azerbaijan. Different frameworks have been suggested for measuring environmental beliefs stemming from well-known anthropocentric and biocentric worldviews. The study addresses New Ecological Paradigm (NEP) by Dunlap to formulate the interview questions as discussion with teachers around these questions aligns with the research aims serving to well-capture the beliefs of teachers about the environment. Despite the extensive applicability of the NEP scale, it has not been used to explore in-service teachers’ beliefs about the environment. Besides, it has been used as a tool for quantitative measurement; however, the study addresses the scale within the framework of the qualitative study. The research population for semi-structured interviews and observations was recruited via purposeful sampling. Teachers’ being a unit of analysis is related to the gap in the literature as to how teachers’ beliefs are related to their classroom instructions within the environmental context, as well as teachers’ beliefs about the environment in Azerbaijan have not been well researched. 6 geography teachers from 4 different schools were involved in the research process. The schools are located in one of the most polluted parts of the capital city Baku where the first oil well in the world was drilled in 1848 and is called “Black City” due to the black smoke and smell that covered that part of the city. Semi-structured interviews were conducted with the teachers to reveal their stated beliefs. Later, teachers were observed during geography classes to understand the overlap between teachers’ ideas presented during the interview and their teaching practice. Research findings aim to indicate teachers’ ecological beliefs and practice, as well as elaborate on possible causes of compatibility/incompatibility between teachers’ stated and observed beliefs.

Keywords: environmental education, anthropocentric beliefs, biocentric beliefs, new ecological paradigm

Procedia PDF Downloads 79

Authors: Xiaowei Zhang, Min Xu, Saeid Habibi, Fengjun Yan, Ryan Ahmed

Abstract:

Recently, Electric Vehicles (EVs) have received extensive consideration since they offer a more sustainable and greener transportation alternative compared to fossil-fuel propelled vehicles. Lithium-Ion (Li-ion) batteries are increasingly being deployed in EVs because of their high energy density, high cell-level voltage, and low rate of self-discharge. Since Li-ion batteries represent the most expensive component in the EV powertrain, accurate monitoring and control strategies must be executed to ensure their prolonged lifespan. The Battery Management System (BMS) has to accurately estimate parameters such as the battery State-of-Charge (SOC), State-of-Health (SOH), and Remaining Useful Life (RUL). In order for the BMS to estimate these parameters, an accurate and control-oriented battery model has to work collaboratively with a robust state and parameter estimation strategy. Since battery physical parameters, such as the internal resistance and diffusion coefficient change depending on the battery state-of-life (SOL), the BMS has to be adaptive to accommodate for this change. In this paper, an extensive battery aging study has been conducted over 12-months period on 5.4 Ah, 3.7 V Lithium polymer cells. Instead of using fixed charging/discharging aging cycles at fixed C-rate, a set of real-world driving scenarios have been used to age the cells. The test has been interrupted every 5% capacity degradation by a set of reference performance tests to assess the battery degradation and track model parameters. As battery ages, the combined model parameters are optimized and tracked in an offline mode over the entire batteries lifespan. Based on the optimized model, a state and parameter estimation strategy based on the Extended Kalman Filter (EKF) and the relatively new Smooth Variable Structure Filter (SVSF) have been applied to estimate the SOC at various states of life.

Keywords: lithium-ion batteries, genetic algorithm optimization, battery aging test, parameter identification

Procedia PDF Downloads 239

Authors: Sofiya An, Akbota Kanderzhanova, Assel Akhmetova, Faye Foster, Chee K. Chan

Abstract:

Healthcare, education and social support for children with autism in Kazakhstan has been evolving and transforming over the last three decades. There is still limited knowledge of the use of complementary and alternative medicine by families caring for autistic children in this post-Soviet region. An exploratory qualitative focus group study of Kazakhstani families was carried out to capture and understand their experiences of using complementary and alternative (CAM) medicine. A total of six focus groups were conducted in five cities across the country including Nur-Sultan, Almaty, Kyzylorda, Karaganda and Taraz. The perceived factors driving the availability, choice, and use of complementary and alternative medicine by families of autistic children in the country were distilled and evaluated. The data collected was analyzed using a framework analysis and themes and subthemes were developed. Two major themes stood out. The first was the “unmet needs”, which relates to the predisposing factors that motivate parents to CAM uptake, and the second was the “chasing hope”, which relates to the enabling factors that facilitate parents’ uptake of CAM. Fear of missing out (FOMO) is a latent underlying motivation underscoring these two themes as well. Parents of autism spectrum disorder (ASD) children in Kazakhstan have to deal with many challenges when seeking treatment for their children with ASD. They are prepared and resort to try out whatever CAM interventions available. The motivation and rationale of choice of use is driven by the lack of options and the hope of any potential positive outcome rather than from rational decisions based on efficacy or the evidence-based data of CAM. Parents get desperate and are willing to try CAM regardless of and independent of their cultural and belief systems and they do not want to miss out just in case it might work. This study also gives an international and cross-cultural perspective on the motives, choice and practice of parents with ASD children using CAM in Kazakhstan, a Central Asian country.

Keywords: autism spectrum disorder, Central Asia, complementary and alternative medicine, cross-cultural perspective, qualitative research

Procedia PDF Downloads 118

Authors: Luis Lara-Valencia, Mateo Ramirez-Acevedo, Daniel Caicedo, Jose Brito, Yosef Farbiarz

Abstract:

Controlling wind-induced vibrations as well as aerodynamic forces, is an essential part of the structural design of tall buildings in order to guarantee the serviceability limit state of the structure. This paper presents a numerical investigation on the optimal design parameters of a Tuned Inerter Damper (TID) based system for the control of wind-induced vibration in tall buildings. The control system is based on the conventional TID, with the main difference that its location is changed from the ground level to the last two story-levels of the structural system. The TID tuning procedure is based on an evolutionary cultural algorithm in which the optimum design variables defined as the frequency and damping ratios were searched according to the optimization criteria of minimizing the root mean square (RMS) response of displacements at the nth story of the structure. A Monte Carlo simulation was used to represent the dynamic action of the wind in the time domain in which a time-series derived from the Davenport spectrum using eleven harmonic functions with randomly chosen phase angles was reproduced. The above-mentioned methodology was applied on a case-study derived from a 37-story prestressed concrete building with 144 m height, in which the wind action overcomes the seismic action. The results showed that the optimally tuned TID is effective to reduce the RMS response of displacements up to 25%, which demonstrates the feasibility of the system for the control of wind-induced vibrations in tall buildings.

Keywords: evolutionary cultural algorithm, Monte Carlo simulation, tuned inerter damper, wind-induced vibrations

Procedia PDF Downloads 113

Authors: Mohammed Kadhim, Zhaohui Huang

Abstract:

Steel connections can play an important role in enhancing the robustness of structures under fire conditions. Therefore, it is significant to examine the influence of steel connections on the fire resistance of composite steel-framed buildings. In this paper, both the behavior of steel connections and their influence on composite steel frame are analyzed using the non-linear finite element computer software VULCAN at ambient and elevated temperatures. The chosen frame is subjected to ISO834 fire. The comparison between end plate connections, pinned connection, and rigid connection has been carried out. By applying different compartment fires, some cases are studied to show the behavior of steel connection when the fire is applied at certain beams. In addition, different plate thickness and deferent applied loads have been analyzed to examine the behavior of chosen steel connection under ISO834 fire. It was found from the analytical results that the beam with extended end plate is stronger and has better performance in terms of axial forces than those beams with flush end plate connection. It was also found that extended end plate connection has highest limiting temperatures compared to the flush end plate connection. In addition, it was found that the performance of end-plate connections is very close to rigid connection and very far from pinned connections. Furthermore, plate thickness has less effect on the influence of steel connection on fire resistance. In conclusion, the behavior of composite steel framed buildings is largely dependent on the steel connection due to their high impact under fire condition. It is recommended to consider the extended end-plate in the design proposes because of its higher properties compared to the flush end plate connection. Finally, this paper shows a steel connection has an important effect on the fire resistance of composite steel framed buildings.

Keywords: composite steel-framed buildings, connection behavior, end-plate connections, finite element modeling, fire resistance

Procedia PDF Downloads 120

Authors: Aisling De Paor

Abstract:

Scientific and technological developments are driving genetics and genetic technologies into the public sphere. Scientists are making genetic discoveries as to the make up of the human body and the cause and effect of disease, diversity and disability amongst individuals. Technological innovation in the field of genetics is also advancing, with the development of genetic testing, and other emerging genetic technologies, including gene editing (which offers the potential for genetic modification). In addition to the benefits for medicine, health care and humanity, these genetic advances raise a range of ethical, legal and societal concerns. From an ethical perspective, such advances may, for example, change the concept of humans and what it means to be human. Science may take over in conceptualising human beings, which may push the boundaries of existing human rights. New genetic technologies, particularly gene editing techniques create the potential to stigmatise disability, by highlighting disability or genetic difference as something that should be eliminated or anticipated. From a disability perspective, use (and misuse) of genetic technologies raise concerns about discrimination and violations to the dignity and integrity of the individual. With an acknowledgement of the likely future orientation of genetic science, and in consideration of the intersection of genetics and disability, this paper highlights the main concerns raised as genetic science and technology advances (particularly with gene editing developments), and the consequences for disability and human rights. Through the use of traditional doctrinal legal methodologies, it investigates the use (and potential misuse) of gene editing as creating the potential for a unique form of discrimination and stigmatization to develop, as well as a potential gateway to a form of new, subtle eugenics. This article highlights the need to maintain caution as to the use, application and the consequences of genetic technologies. With a focus on the law and policy position in Europe, it examines the need to control and regulate these new technologies, particularly gene editing. In addition to considering the need for regulation, this paper highlights non-normative approaches to address this area, including awareness raising and education, public discussion and engagement with key stakeholders in the field and the development of a multifaceted genetics advisory network.

Keywords: disability, gene-editing, genetics, law, regulation

Procedia PDF Downloads 330

Authors: Shimaa Mahmoud Ali Ahmed, Boshra Tawfek El-Shreef

Abstract:

Sustainable development has become an important concern worldwide, and climate change has become a global threat. Some of these affect how we approach environmental issues — and how we should approach them. Environmental aspects have an important impact on the built environment, that’s why knowledge about Green Building and Green Construction become a vital dimension of urban sustainable development to face the challenges of climate change. There are several levels of green buildings, from energy-efficient lighting to 100% eco-friendly construction; the concept of green buildings in Egypt is still a rare occurrence, with the concept being relatively new to the market. There are several projects on the ground that currently employing sustainable and green solutions to some extent, some of them achieve a limit of success and others fail to employ the new solutions. The market and the cost as well, are great factors. From the last century, green architecture and environmental sustainability become a famous trend that all the researchers like to follow. Nowadays, the trend towards green has shifted to housing and real estate projects. While the environmental aspects are the key to achieve green buildings, the economic benefits, and the market forces are considered as big challenges. The paper assumes that some appropriate environmental treatments could be added to the applied prototype of the governmental social housing projects in Egypt to achieve better environmental solutions. The aim of the research is to get housing projects in Egypt closer to the track of sustainable and green buildings, through making a local future proposal to be integrated into the current policies. The proposed model is based upon adding some appropriate, cheap environmental modifications to the prototype of the Ministry of Housing, Infrastructure, and New Urban Communities. The research is based on an analytical, comparative analytical, and inductive approach to study and analyze the housing projects in Egypt and the possibilities of integrating green techniques into it.

Keywords: green buildings, urban sustainability, housing projects, sustainable development goals, Egypt 2030

Procedia PDF Downloads 99

Authors: Asif Zaman, Moinul Islam Zaber, Amin Ahsan Ali

Abstract:

In recent years of industrialization, the South Asian countries are being affected by air pollution due to a severe increase in fine particulate matter 2.5 (PM₂.₅). Among them, Bangladesh is one of the most polluting countries. In this paper, statistical analyses were conducted on the time series of PM₂.₅ from various districts in Bangladesh, mostly around Dhaka city. Research has been conducted on the dynamic interactions and relationships between PM₂.₅ concentrations in different zones. The study is conducted toward understanding the characteristics of PM₂.₅, such as spatial-temporal characterization, correlation of other contributors behind air pollution such as human activities, driving factors and environmental casualties. Clustering on the data gave an insight on the districts groups based on their AQI frequency as representative districts. Seasonality analysis on hourly and monthly frequency found higher concentration of fine particles in nighttime and winter season, respectively. Cross correlation analysis discovered a phenomenon of correlations among cities based on time-lagged series of air particle readings and visualization framework is developed for observing interaction in PM₂.₅ concentrations between cities. Significant time-lagged correlations were discovered between the PM₂.₅ time series in different city groups throughout the country by cross correlation analysis. Additionally, seasonal heatmaps depict that the pooled series correlations are less significant in warmer months, and among cities of greater geographic distance as well as time lag magnitude and direction of the best shifted correlated particulate matter time series among districts change seasonally. The geographic map visualization demonstrates spatial behaviour of air pollution among districts around Dhaka city and the significant effect of wind direction as the vital actor on correlated shifted time series. The visualization framework has multipurpose usage from gathering insight of general and seasonal air quality of Bangladesh to determining the pathway of regional transportation of air pollution.

Keywords: air quality, particles, cross correlation, seasonality

Procedia PDF Downloads 86

Authors: Semayat Fanta, P.M. Mohite, C.S. Upadhyay

Abstract:

Damage meso-model for laminates is one of the most widely applicable approaches for the analysis of damage induced in laminated fiber-reinforced polymeric composites. Damage meso-model for laminates has been developed over the last three decades by many researchers in experimental, theoretical, and analytical methods that have been carried out in micromechanics as well as meso-mechanics analysis approaches. It has been fundamentally developed based on the micromechanical description that aims to predict the damage initiation and evolution until the failure of structure in various loading conditions. The current damage meso-model for laminates aimed to act as a bridge between micromechanics and macro-mechanics of the laminated composite structure. This model considers two meso-constituents for the analysis of damage in ply and interface that imparted from low-velocity impact. The damages considered in this study include fiber breakage, matrix cracking, and diffused damage of the lamina, and delamination of the interface. The damage initiation and evolution in laminae can be modeled in terms of damaged strain energy density using damage parameters and the thermodynamic irreversible forces. Interface damage can be modeled with a new concept of spherical micro-void in the resin-rich zone of interface material. The damage evolution is controlled by the damage parameter (d) and the radius of micro-void (r) from the point of damage nucleation to its saturation. The constitutive martial model for meso-constituents is defined in a user material subroutine VUMAT and implemented in ABAQUS/Explicit finite element modeling tool. The model predicts the damages in the meso-constituents level very accurately and is considered the most effective technique of modeling low-velocity impact simulation for laminated composite structures.

Keywords: mesomodel, laminate, low-energy impact, micromechanics

Procedia PDF Downloads 197

Authors: Bahiru Tsegaye, Chandrajit Balomajumder, Partha Roy

Abstract:

The limited supply and related negative environmental consequence of fossil fuels are driving researcher for finding sustainable sources of energy. Lignocellulose biomass like sorghum straw is considered as among cheap, renewable and abundantly available sources of energy. However, lignocellulose biomass conversion to bioenergy like bioethanol is hindered due to the reluctant nature of lignin in the biomass. Therefore, removal of lignin is a vital step for lignocellulose conversion to renewable energy. The aim of this study is to optimize microwave pretreatment conditions using design expert software to remove lignin and to release maximum possible polysaccharides from sorghum straw for efficient hydrolysis and fermentation process. Sodium hydroxide concentration between 0.5-1.5%, v/v, pretreatment time from 5-25 minutes and pretreatment temperature from 120-2000C were considered to depolymerize sorghum straw. The effect of pretreatment was studied by analyzing the compositional changes before and after pretreatments following renewable energy laboratory procedure. Analysis of variance (ANOVA) was used to test the significance of the model used for optimization. About 32.8%-48.27% of hemicellulose solubilization, 53% -82.62% of cellulose release, and 49.25% to 78.29% lignin solubilization were observed during microwave pretreatment. Pretreatment for 10 minutes with alkali concentration of 1.5% and temperature of 1400C released maximum cellulose and lignin. At this optimal condition, maximum of 82.62% of cellulose release and 78.29% of lignin removal was achieved. Sorghum straw at optimal pretreatment condition was subjected to enzymatic hydrolysis and fermentation. The efficiency of hydrolysis was measured by analyzing reducing sugars by 3, 5 dinitrisylicylic acid method. Reducing sugars of about 619 mg/g of sorghum straw were obtained after enzymatic hydrolysis. This study showed a significant amount of lignin removal and cellulose release at optimal condition. This enhances the yield of reducing sugars as well as ethanol yield. The study demonstrates the potential of microwave pretreatments for enhancing bioethanol yield from sorghum straw.

Keywords: cellulose, hydrolysis, lignocellulose, optimization

Procedia PDF Downloads 242

Authors: N. V. Klassen, A. A. Vasin, A. M. Likhter, K. A. Voronin, A. V. Mariasevskaya, I. M. Shmit’ko

Abstract:

Regular patterning in mixtures of bio-polymers (chitosan and collagen) and nanoparticles in water suspensions has been found by means of optical microscopy. The patterning was created either by external electrical field of moderate amplitude (200–1000 v/cm) or spontaneously. Simultaneously with the patterning pushing out of water drops mixed with nanoparticles to the external regions was observed. These phenomena are explained by interactions of charged bio-polymers and nanoparticles with external and internal electrical fields as well as with the regions of decreased dielectrical permittivity surrounding nano-objects in water which possesses anomalously high dielectrical permittivity. Electrical charges of opposite signs of the nano-objects induce their mutual attraction whereas dipole moments created around these nano-objects by the electrical fields are pushing these particles to the regions with lower fields. Due to this reason, non-homogeneities of dielectrical permittivity around nano-objects immersed into water suspension induces mutual repulsion of the objects. This spatial decrease of this repulsion with the inter-particle distances is more sharp than that of the Coulomb attraction. So, at longer distances, the attractions are stronger whereas at shorter distances the repulsion prevails. At a certain distance these two forces compensate each other creating the equilibrium state of the mixture of nano-objects with opposite charges. When the groups of positive and negative nano-objects consist from identical particles, quasi-periodical pattern of the suspension is observed like mesoscopic two-dimensional super-crystal. These results can clarify the mechanisms of healing of internal organs with direct or alternative electrical fields.

Keywords: bio-polymers, chitosan, collagen, nanoparticles, Coulomb attraction, polarization repulsion, periodical patterning, electrical low frequency resonances

Procedia PDF Downloads 420

Authors: Muhammad Awais Kiani, Maryam Kiani

Abstract:

This abstract explores the confluence of these two domains and highlights the key factors driving success in sales marketing for electronics. The abstract begins by digging into the ever-evolving landscape of consumer electronics, emphasizing how technological advancements and the growth of smart devices have revolutionized the way people interact with electronics. This paradigm shift has created tremendous opportunities for sales and marketing professionals to engage with consumers on various platforms and channels. Next, the abstract discusses the pivotal role of effective sales marketing strategies in the electronics industry. It highlights the importance of understanding consumer behavior, market trends, and competitive landscapes and how this knowledge enables businesses to tailor their marketing efforts to specific target audiences. Furthermore, the abstract explores the significance of leveraging digital marketing techniques, such as social media advertising, search engine optimization, and influencer partnerships, to establish brand identity and drive sales in the electronics market. It emphasizes the power of storytelling and creating captivating content to engage with tech-savvy consumers. Additionally, the abstract emphasizes the role of customer relationship management (CRM) systems and data analytics in optimizing sales marketing efforts. It highlights the importance of leveraging customer insights and analyzing data to personalize marketing campaigns, enhance customer experience, and ultimately drive sales growth. Lastly, the abstract concludes by underlining the importance of adapting to the ever-changing landscape of the electronics industry. It encourages businesses to embrace innovation, stay informed about emerging technologies, and continuously evolve their sales marketing strategies to meet the evolving needs and expectations of consumers. Overall, this abstract sheds light on the captivating realm of sales marketing in the electronics industry, emphasizing the need for creativity, adaptability, and a deep understanding of consumers to succeed in this rapidly evolving market.

Keywords: marketing industry, electronics, sales impact, e-commerce

Procedia PDF Downloads 45

Authors: Shaho Ghafur Ahmed

Abstract:

The right to self-determination of peoples is a fundamental human right recognized by the principles of international law. It could be embodied in the internal level in the form of federalism. Most federal constitutions prevented the secession of constituent entities, while some remained silent, as the case of Iraq, and rare instances of them recognize it. But, after the failure of federalism, these entities seek to separate whenever the opportunity arises. In several cases, they have resort to peaceful methods in some others they resort to force. The constitutional Supreme Court, which guaranty the unity and integrity of the State, often prevent these attempts. After not a commitment of federalism in Iraq, which has been founded since 2004, the Kurdistan region, as the only federated entity, has conducted a unilateral referendum on 25 September 2017 for its independence. The Iraqi government refused it. The Iraqi Federal Supreme Court, through interpreting the constitutional provisions, decided that this referendum and it’s purposes, which was the independence of the region, was unconstitutional. Subsequently, the Iraqi government used forces and blockaded the region so as to force it to turn off this process. So, in this paper, the right to self-determination of the peoples in federated entities and its obstacles will be discussed through the comparative legal basis and analyzing the decisions of the Federal Constitutional Courts. We will compare the role that the Supreme Court of Canada played regarding the referendum that operated in Quebec in 1995, in which it refused only the unilaterally attempts for the independence of this province. While, in the case of the Kurdistan region, the Iraqi Federal Supreme Court has definitively refused this right. No measures were taken by this Court to protect the region from the Iraqi government reactions. This decision led to the questioning of the neutrality of this Court. So, from the point of view of the Kurdistan region, this Court became a political instrument to prevent it to be independent in the international community, in the absence of a clear constitutional provision, through an abstract and an incomplete interpretation of federal constitutional provisions.

Keywords: right of self-determination, federal supreme court, supremacy of federal constitution

Procedia PDF Downloads 138

Authors: Mark Lin, Periklis Papadopoulos

Abstract:

This paper explores the aerodynamics of the formula racecar when a ‘halo’ driver-protection device is added to the chassis. The halo protection device was introduced at the start of the 2018 racing season as a safety measure against foreign object impacts that a driver may encounter when driving an open-wheel racecar. In the one-year since its introduction, the device has received wide acclaim for protecting the driver on two separate occasions. The benefit of such a safety device certainly cannot be disputed. However, by adding the halo device to a car, it changes the airflow around the vehicle, and most notably, to the engine air-intake and the rear wing. These negative effects in the air supply to the engine, and equally to the downforce created by the rear wing are studied in this paper using numerical technique, and the resulting CFD outputs are presented and discussed. Comparing racecar design prior to and after the introduction of the halo device, it is shown that the design of the air intake and the rear wing has not followed suit since the addition of the halo device. The reduction of engine intake mass flow due to the halo device is computed and presented for various speeds the car may be going. Because of the location of the halo device in relation to the air intake, airflow is directed away from the engine, making the engine perform less than optimal. The reduction is quantified in this paper to show the correspondence to reduce the engine output when compared to a similar car without the halo device. This paper shows that through aerodynamic arguments, the engine in a halo car will not receive unobstructed, clean airflow that a non-halo car does. Another negative effect is on the downforce created by the rear wing. Because the amount of downforce created by the rear wing is influenced by every component that comes before it, when a halo device is added upstream to the rear wing, airflow is obstructed, and less is available for making downforce. This reduction in downforce is especially dramatic as the speed is increased. This paper presents a graph of downforce over a range of speeds for a car with and without the halo device. Acknowledging that although driver safety is paramount, the negative effect of this safety device on the performance of the car should still be well understood so that any possible redesign to mitigate these negative effects can be taken into account in next year’s rules regulation.

Keywords: automotive aerodynamics, halo device, downforce. engine intake

Procedia PDF Downloads 80

Authors: María Dolores Caro, Eugenio M. Fedriani, Ángel F. Tenorio

Abstract:

The transportation of dangerous goods by lorries throughout Europe must be done by using the roads conforming the European Road Transport Network. In this network, there are several parking areas where lorry drivers can park to rest according to the regulations. According to the "European Agreement concerning the International Carriage of Dangerous Goods by Road", parking areas where lorries transporting dangerous goods can park to rest, must follow several security stipulations to keep safe the rest of road users. At this respect, these lorries must be parked in adapted areas with strict and permanent surveillance measures. Moreover, drivers must satisfy several restrictions about resting and driving time. Under these facts, one may expect that there exist enough parking areas for the transport of this type of goods in order to obey the regulations prescribed by the European Union and its member countries. However, the already-existing parking areas are not sufficient to cover all the stops required by drivers transporting dangerous goods. Our main goal is, starting from the already-existing parking areas and the loading-and-unloading location, to provide an optimal answer to the following question: how many additional parking areas must be built and where must they be located to assure that lorry drivers can transport dangerous goods following all the stipulations about security and safety for their stops? The sense of the word “optimal” is due to the fact that we give a global solution for the location of parking areas throughout the whole European Road Transport Network, adjusting the number of additional areas to be as lower as possible. To do so, we have modeled the problem using graph theory since we are working with a road network. As nodes, we have considered the locations of each already-existing parking area, each loading-and-unloading area each road bifurcation. Each road connecting two nodes is considered as an edge in the graph whose weight corresponds to the distance between both nodes in the edge. By applying a new efficient algorithm, we have found the additional nodes for the network representing the new parking areas adapted for dangerous goods, under the fact that the distance between two parking areas must be less than or equal to 400 km.

Keywords: trans-european transport network, dangerous goods, parking areas, graph-based modeling

Procedia PDF Downloads 253

Authors: Yasser Almazrua

Abstract:

Terrorism is a multidimensional phenomenon that has increased recently. Many countries started combating terrorism through security forces; however, there has been relatively little attention given to rehabilitation programs for people involved in such terrorism acts. In Saudi Arabia, after facing so many terrorist attacks, they started understanding and countering terrorism differently by establishing Mohammad bin Naif Counselling and Care Center in 2006. The center now is considered one of the top experience centers in the world for terrorist rehabilitation and ideology correction. The center offers different programs such as training, educational, social, art and psychological programs. One of the approaches that have been used by psychological experts at the center is Narrative Therapy. It is a therapeutic approach that focuses on the ability of the client to identify their personal life story. The client during therapy works as a storyteller where he or she gets insight, meaning and better understanding of their own lives. Because each client at the center had a story, it can be better fit method for rehabilitation towards healing and personal development. The case describes a 34-years-old man who was involved in some terrorism activities locally by technically and financially supporting a terrorist group related to Al-Qaida. The beneficiary joined Mohammad bin Naif Counseling and Care Center after serving his sentence. Informed of consent has been given to the beneficiary before starting the therapeutic program. Both qualitative and quantitative data on the beneficiary are collected by self-reporting during the initial session, and by using a psychological measurement. The result found that the beneficiary was not insightful about himself, and he had a high level of repression which relatedly moved him to be targeted for recruitment in the terrorist group. With rehabilitation and by using the therapeutic approach, the beneficiary improved on the level of insight, specifically about himself and also about the experience. This case illustrates the importance of considering the effect of Narrative Therapy in terrorist rehabilitation programs.

Keywords: narrative therapy, rehabilitation, Saudi Arabia, terrorism

Procedia PDF Downloads 265

Authors: S. Fominow, C. Dobert

Abstract:

The present article describes the research that deals with the development of equivalent geometric imperfections for the stability design of steel members considering lateral-torsional buckling. The application of these equivalent imperfections takes into account the stiffness-reducing effects due to inelasticity and residual stresses, which lead to a reduction of the load carrying capacity of slender members and structures. This allows the application of a simplified design method, that is performed in three steps. Application of equivalent geometric imperfections, determination of internal forces using geometrical non-linear analysis (GNIA) and verification of the cross-section resistance at the most unfavourable location. All three verification steps are closely related and influence the results. The derivation of the equivalent imperfections was carried out in several steps. First, reference lateral-torsional buckling resistances for various rolled I-sections, slenderness grades, load shapes and steel grades were determined. This was done either with geometric and material non-linear analysis with geometrical imperfections and residual stresses (GMNIA) or for standard cases based on the equivalent member method. With the aim of obtaining identical lateral-torsional buckling resistances as the reference resistances from the application of the design method, the required sizes for equivalent imperfections were derived. For this purpose, a program based on the FEM method has been developed. Based on these results, several proposals for the specification of equivalent geometric imperfections have been developed. These differ in the shape of the applied equivalent geometric imperfection, the model of the cross-sectional resistance and the steel grade. The proposed design methods allow a wide range of applications and a reliable calculation of the lateral-torsional buckling resistances, as comparisons between the calculated resistances and the reference resistances have shown.

Keywords: equivalent geometric imperfections, GMNIA, lateral-torsional buckling, non-linear finite element analysis

Procedia PDF Downloads 130

Authors: Semachew M. Kassa, Africa M Geremew, Tezera F. Azmatch, Nandyala Darga Kumar

Abstract:

Frequency ratio (FR) and analytical hierarchy process (AHP) methods are developed based on past landslide failure points to identify the landslide susceptibility mapping because landslides can seriously harm both the environment and society. However, it is still difficult to select the most efficient method and correctly identify the main driving factors for particular regions. In this study, we used fourteen landslide conditioning factors (LCFs) and five soft computing algorithms, including Random Forest (RF), Support Vector Machine (SVM), Logistic Regression (LR), Artificial Neural Network (ANN), and Naïve Bayes (NB), to predict the landslide susceptibility at 12.5 m spatial scale. The performance of the RF (F1-score: 0.88, AUC: 0.94), ANN (F1-score: 0.85, AUC: 0.92), and SVM (F1-score: 0.82, AUC: 0.86) methods was significantly better than the LR (F1-score: 0.75, AUC: 0.76) and NB (F1-score: 0.73, AUC: 0.75) method, according to the classification results based on inventory landslide points. The findings also showed that around 35% of the study region was made up of places with high and very high landslide risk (susceptibility greater than 0.5). The very high-risk locations were primarily found in the western and southeastern regions, and all five models showed good agreement and similar geographic distribution patterns in landslide susceptibility. The towns with the highest landslide risk include Amhara Saint Town's western part, the Northern part, and St. Gebreal Church villages, with mean susceptibility values greater than 0.5. However, rainfall, distance to road, and slope were typically among the top leading factors for most villages. The primary contributing factors to landslide vulnerability were slightly varied for the five models. Decision-makers and policy planners can use the information from our study to make informed decisions and establish policies. It also suggests that various places should take different safeguards to reduce or prevent serious damage from landslide events.

Keywords: artificial neural network, logistic regression, landslide susceptibility, naïve Bayes, random forest, support vector machine

Procedia PDF Downloads 37

Authors: Akram Khelaifia, Salah Guettala, Nesreddine Djafar Henni, Rachid Chebili

Abstract:

Reinforced concrete shear walls are pivotal in protecting buildings from seismic forces by providing strength and stiffness. This study highlights the importance of strategically placing shear walls and optimizing the shear wall-to-floor area ratio in building design. Nonlinear analyses were conducted on an eight-story building situated in a high seismic zone, exploring various scenarios of shear wall positioning and ratios to floor area. Employing the performance-based seismic design (PBSD) approach, the study aims to meet acceptance criteria such as inter-story drift ratio and damage levels. The results indicate that concentrating shear walls in the middle of the structure during the design phase yields superior performance compared to peripheral distributions. Utilizing shear walls that fully infill the frame and adopting compound shapes (e.g., Box, U, and L) enhances reliability in terms of inter-story drift. Conversely, the absence of complete shear walls within the frame leads to decreased stiffness and degradation of shorter beams. Increasing the shear wall-to-floor area ratio in building design enhances structural rigidity and reliability regarding inter-story drift, facilitating the attainment of desired performance levels. The study suggests that a shear wall ratio of 1.0% is necessary to meet validation criteria for inter-story drift and structural damage, as exceeding this percentage leads to excessive performance levels, proving uneconomical as structural elements operate near the elastic range.

Keywords: nonlinear analyses, pushover analysis, shear wall, plastic hinge, performance level

Procedia PDF Downloads 19

Authors: Karl Gerrard Tiu See

Abstract:

Military bases are an indelible mark of prolonged US defense relationships in the Pacific. Bases like the Subic Naval Base in Olongapo City have irreversible consequences for their host communities, not all of which are positive. One consequence the Subic Naval Base had for Olongapo City was the rise of vibrant sex industry. While the Philippine Senate voted to remove US bases like Subic in 1991, the question remains as to why did prostitution not end after the bases pull-out? To answer this question, the study used an institutionalist lens coupled with focus group discussions from the sex industry. It found that prostitution persisted due to two main reasons. The first was that like Olongapo City; the sex industry successfully shifted its reliance from the military to foreign tourism. The second was that agreements such as the 1996 Visiting Forces Agreement (VFA) ensured that the sex industry continued to receive US military clientele. With the contextual factors as the backdrop, this study used the Theory of Institutional Change to study institutions pivotal in altering Olongapo City and its sex industry after Subic Naval Base. These include local government, civil society actors such as NGOs, and the city’s economic base. The study found that policy such as the VFA allowed the bases period status quo to revive (Symbionts). This led to renewed exploitation from the military presence coupled with foreign tourism (Opportunists). The local government, however, shifted focus away from base reliance which allowed a reinvigorated civil society to effect a gradual change (Subversives). Furthermore, uncertainties like rising HIV incidence, abandoned children born from US soldiers, and the Enhanced Defence Cooperation Agreement (EDCA) remain to change the sex industry’s future, for better or worse.

Keywords: Philippine-USA defence relations, overseas USA basing, 1991 Philippine-USA bases pull-out, Olongapo city, Subic naval base, institutional change

Procedia PDF Downloads 381

Authors: Mornay Roberts-Lombard

Abstract:

Consumers’ perceptions of value are crucial to ensuring their future commitment and behavioral intentions. As a result, service providers, such as Islamic banks, must provide their customers with products and services that are regarded as valuable, stimulating, collaborative, and competent. Therefore, the value provided to customers must meet or surpass their expectations, which can drive customers’ commitment (affective and calculative) and eventually favorably impact their future behavioral intentions. Consequently, Islamic banks in South Africa, as a growing African market, need to obtain a better understanding of the variables that impact Islamic banking customers’ value perceptions and how these impact their future behavioral intentions. Furthermore, it is necessary to investigate how customers’ perceived value perceptions impact their affective and calculative commitment and how the latter impact their future behavioral intentions. The purpose of this study is to bridge these gaps in knowledge, as the competitiveness of the Islamic banking industry in South Africa requires a deeper understanding of the aforementioned relationships. The study was exploratory and quantitative in nature, and data was collected from 250 Islamic banking customers using self-administered questionnaires. These banking customers resided in the Gauteng province of South Africa. Exploratory factor analysis, Pearson’s coefficient analysis, and multiple regression analysis were applied to measure the proposed hypotheses developed for the study. This research will aid Islamic banks in the country in potentially strengthening customers’ future commitment (affective and calculative) and positively impact their future behavioral intentions. The findings of the study established that service quality has a significant and positive impact on perceived value. Moreover, it was determined that perceived value has a favorable and considerable impact on affective and calculative commitment, while calculative commitment has a beneficial impact on behavioral intention. The research informs Islamic banks of the importance of service engagement in driving customer perceived value, which stimulates the future affective and calculative commitment of Islamic bank customers in an emerging market context. Finally, the study proposes guidelines for Islamic banks to develop an enhanced understanding of the factors that impact the perceived value-commitment-behavioral intention link in a competitive Islamic banking market in South Africa.

Keywords: perceived value, affective commitment, calculative commitment, behavioural intention

Procedia PDF Downloads 32

Authors: Amanina Iymia Jeffree, Reena Thriumani, Mohammad Iqbal Omar, Ammar Zakaria, Yumi Zuhanis Has-Yun Hashim, Ali Yeon Md Shakaff

Abstract:

Metabolite profiling is a strategy to be approached in the pattern recognition method focused on three types of cancer cell line that driving the most to death specifically lung, breast, and colon cancer. The purpose of this study was to discriminate the VOCs pattern among cancerous and control group based on metabolite profiling. The sampling was executed utilizing the cell culture technique. All culture flasks were incubated till 72 hours and data collection started after 24 hours. Every running sample took 24 minutes to be completed accordingly. The comparative metabolite patterns were identified by the implementation of headspace-solid phase micro-extraction (HS-SPME) sampling coupled with gas chromatography-mass spectrometry (GCMS). The optimizations of the main experimental variables such as oven temperature and time were evaluated by response surface methodology (RSM) to get the optimal condition. Volatiles were acknowledged through the National Institute of Standards and Technology (NIST) mass spectral database and retention time libraries. To improve the reliability of significance, it is of crucial importance to eliminate background noise which data from 3rd minutes to 17th minutes were selected for statistical analysis. Targeted metabolites, of which were annotated as known compounds with the peak area greater than 0.5 percent were highlighted and subsequently treated statistically. Volatiles produced contain hundreds to thousands of compounds; therefore, it will be optimized by chemometric analysis, such as principal component analysis (PCA) as a preliminary analysis before subjected to a pattern classifier for identification of VOC samples. The volatile organic compound profiling has shown to be significantly distinguished among cancerous and control group based on metabolite profiling.

Keywords: in vitro cancer cell line, metabolite profiling, pattern recognition, volatile organic compounds

Procedia PDF Downloads 343

Authors: Su-Thing Ho, Shiao-Shing Chen, Hung-Te Hsu, Saikat Sinha Ray

Abstract:

Forward osmosis (FO) is an emerging technology for direct and indirect potable water reuse application. However, successful implementation of FO is still hindered by the lack of draw solution recovery with high efficiency. Membrane distillation (MD) is a thermal separation process by using hydrophobic microporous membrane that is kept in sandwich mode between warm feed stream and cold permeate stream. Typically, temperature difference is the driving force of MD which attributed by the partial vapor pressure difference across the membrane. In this study, the direct contact membrane distillation (DCMD) system was used to recover diluted draw solution of FO. Na3PO4 at pH 9 and EDTA-2Na at pH 8 were used as the feed solution for MD since it produces high water flux and minimized salt leakage in FO process. At high pH, trivalent and tetravalent ions are much easier to remain at draw solution side in FO process. The result demonstrated that PTFE with pore size of 1 μm could achieve the highest water flux (12.02 L/m2h), followed by PTFE 0.45 μm (10.05 L/m2h), PTFE 0.1 μm (7.38 L/m2h) and then PP (7.17 L/m2h) while using 0.1 M Na3PO4 draw solute. The concentration of phosphate and conductivity in the PTFE (0.45 μm) permeate were low as 1.05 mg/L and 2.89 μm/cm respectively. Although PTFE with the pore size of 1 μm could obtain the highest water flux, but the concentration of phosphate in permeate was higher than other kinds of MD membranes. This study indicated that four kinds of MD membranes performed well and PTFE with the pore size of 0.45 μm was the best among tested membranes to achieve high water flux and high rejection of phosphate (99.99%) in recovery of diluted draw solution. Besides that, the results demonstrate that it can obtain high water flux and high rejection of phosphate when operated with cross flow velocity of 0.103 m/s with Tfeed of 60 ℃ and Tdistillate of 20 ℃. In addition to that, the result shows that Na3PO4 is more suitable for recovery than EDTA-2Na. Besides that, while recovering the diluted Na3PO4, it can obtain the high purity of permeate water. The overall performance indicates that, the utilization of DCMD is a promising technology to recover the diluted draw solution for FO process.

Keywords: membrane distillation, forward osmosis, draw solution, recovery

Procedia PDF Downloads 162

Authors: Yannay Casas-Ledon, Cinthya A. Andrade, Camila E. Salazar, Mauricio Aguayo

Abstract:

The sustainable management of available natural resources is a crucial question for policy-makers, economists, and the research community. Among several, land constitutes one of the most critical resources, which is being intensively appropriated by human activities producing ecological stresses and reducing ecosystem services. In this context, net primary production (NPP) has been considered as a feasible proxy indicator for estimating the impacts of human interventions on land-uses intensity. Accordingly, the human appropriation of NPP (HANPP) was calculated for the south-central regions of Chile between 2007 and 2014. The HANPP was defined as the difference between the potential NPP of the naturally produced vegetation (NPP0, i.e., the vegetation that would exist without any human interferences) and the NPP remaining in the field after harvest (NPPeco), expressed in gC/m² yr. Other NPP flows taken into account in HANPP estimation were the harvested (NPPh) and the losses of NPP through land conversion (NPPluc). The ArcGIS 10.4 software was used for assessing the spatial and temporal HANPP changes. The differentiation of HANPP as % of NPP0 was estimated by each landcover type taken in 2007 and 2014 as the reference years. The spatial results depicted a negative impact on land use efficiency during 2007 and 2014, showing negative HANPP changes for the whole region. The harvest and biomass losses through land conversion components are the leading causes of loss of land-use efficiency. Furthermore, the study depicted higher HANPP in 2014 than in 2007, representing 50% of NPP0 for all landcover classes concerning 2007. This performance was mainly related to the higher volume of harvested biomass for agriculture. In consequence, the cropland depicted the high HANPP followed by plantation. This performance highlights the strong positive correlation between the economic activities developed into the region. This finding constitutes the base for a better understanding of the main driving force influencing biomass productivity and a powerful metric for supporting the sustainable management of land use.

Keywords: human appropriation, land-use changes, land-use impact, net primary productivity

Procedia PDF Downloads 110

Authors: Mohammed Islam

Abstract:

Graduate employability is a well debated topic by governments, employers, and higher education institutes (HEI) across the world. Much of the focus of these debates have centred around the skills that graduates bring or should bring to the job market, a point echoed by United Arab Emirates (UAE) policy makers and employers. While some research has been carried out on graduates' employability skills, little or no attention has been paid to the forces at play in developing employability policy and its subsequent implementation. The focus of debate has been on a perceived skills gap rather than policy. Recognising a gap in the literature, this paper details a study of UAE employability policy development. Taking a social constructionist approach, this case study views policy as discursive and socially constructed through interactions with key stakeholders. It is within the myriad of interdependent socio-political factors and social practices, particularly power relationships, that this paper explores UAE policy on graduate employability. In doing so, this adds to the debate on graduate employability from the perspective of policy and explores its roots in the interaction between human activity and the ‘system’. Data was collected from two main sources: documentary review and semi-structured interviews. Policies and publicly stated rhetoric on graduate employability were analysed using Critical Discourse Analysis. Semi-structured interviews with representatives from policy makers, HEIs, and employers were reviewed through Thematic Analysis. The theoretical framework for the discussion of findings draws from social practice theories and highlights the factors at play in access to employment for UAE graduates. This case study presents a methodological approach to policy studies that can be applied beyond the context under investigation. Education policy researchers are provided with an opportunity to compare similarities and differences with their own specific contexts.

Keywords: critical discourse analysis, employability, methodology, policy, social constructionism

Procedia PDF Downloads 102

Authors: Tooran Tavangar, Masoud Hosseinpoor, Jeffrey S. Marshall, Ammar Yahia, Kamal Henri Khayat

Abstract:

In this study, a four-way coupled CFD-DEM methodology was used to simulate the behavior of concrete pipe flow. Fresh concrete, characterized as a biphasic suspension, features aggregates comprising the solid-suspended phase with diverse particle-size distributions (PSD) within a non-Newtonian cement paste/mortar matrix forming the liquid phase. The fluid phase was simulated using CFD, while the aggregates were modeled using DEM. Interaction forces between the fluid and solid particles were considered through CFD-DEM computations. To capture the viscoelastic characteristics of the suspending fluid, a bi-viscous approach was adopted, incorporating a critical shear rate proportional to the yield stress of the mortar. In total, three diphasic suspensions were simulated, each featuring distinct particle size distributions and a concentration of 10% for five subclasses of spherical particles ranging from 1 to 17 mm in a suspending fluid. The adopted bi-viscous approach successfully simulated both un-sheared (plug flow) and sheared zones. Furthermore, shear-induced particle migration (SIPM) was assessed by examining coefficients of variation in particle concentration across the pipe. These SIPM values were then compared with results obtained using CFD-DEM under the Newtonian assumption. The study highlighted the crucial role of yield stress in the mortar phase, revealing that lower yield stress values can lead to increased flow rates and higher SIPM across the pipe.

Keywords: computational fluid dynamics, concrete pumping, coupled CFD-DEM, discrete element method, plug flow, shear-induced particle migration.

Procedia PDF Downloads 33

Authors: Saeed Ilbeigi, Bart Van Gheluwe

Abstract:

The purpose of this study was to identify the three-dimensional kinematics of the sprint start during the start phase of the sprint. The purpose of this study was to identify the three-dimensional kinematics of the sprint start during the start phase of the sprint. Moreover, the effect of anthropometrical factors such as skeletal muscle mass, thigh girth, and calf girth also were considered on the kinematics of the sprint start. Among all young sprinters involved in the national Belgium league, sixty sprinters (boys: 14.7 ± 1.8 years and girls: 14.8±1.5 years) were randomly selected. The kinematics data of the sprint start were collected with a Vicon® 620 motion analysis system equipped with 12 infrared cameras running at 250 Hz and running the Vicon Data Station software. For statistical analysis, T-tests and ANOVA׳s with Scheffé post hoc test were used and the significant level was set as p≤0.05. The results showed that the angular positions of the lower joints of the young sprinters in the set position were comparable with adult figures from literature, however, with a greater range of joint extension. The most significant difference between boys and girls was found in the set position, where the boys presented a more dorsiflexed ankle. No further gender effect was observed during the leaving the blocks and contact phase. The sprinters with a higher age, skeletal muscle mass, thigh girth, and calf girth displayed a better angular position of the lower joints (e.g. ankle, knee, hip) in the set position, a more optimal angular position for the foot and knee for absorbing impact forces at foot contact and finally a higher range of flexion/extension motion to produce force and power when leaving the blocks.

Keywords: anthropometry, kinematics, sprint start, young elite sprinters

Procedia PDF Downloads 194

Authors: Darwin Castillo Huamaní, Francisco A. M. Gomes

Abstract:

The aim of the multi-material topology optimization (MTO) is to obtain the optimal topology of structures composed by many materials, according to a given set of constraints and cost criteria. In this work, we seek the optimal distribution of materials in a domain, such that the flexibility of the structure is minimized, under certain boundary conditions and the intervention of external forces. In the case we have only one material, each point of the discretized domain is represented by two values from a function, where the value of the function is 1 if the element belongs to the structure or 0 if the element is empty. A common way to avoid the high computational cost of solving integer variable optimization problems is to adopt the Solid Isotropic Material with Penalization (SIMP) method. This method relies on the continuous interpolation function, power function, where the base variable represents a pseudo density at each point of domain. For proper exponent values, the SIMP method reduces intermediate densities, since values other than 0 or 1 usually does not have a physical meaning for the problem. Several extension of the SIMP method were proposed for the multi-material case. The one that we explore here is the ordered SIMP method, that has the advantage of not being based on the addition of variables to represent material selection, so the computational cost is independent of the number of materials considered. Although the number of variables is not increased by this algorithm, the optimization subproblems that are generated at each iteration cannot be solved by methods that rely on second derivatives, due to the cost of calculating the second derivatives. To overcome this, we apply a globally convergent version of the sequential linear programming method, which solves a linear approximation sequence of optimization problems.

Keywords: globally convergence, multi-material design ordered simp, sequential linear programming, topology optimization

Procedia PDF Downloads 279