Search results for: cellular structures
4160 Neural Network Mechanisms Underlying the Combination Sensitivity Property in the HVC of Songbirds
Authors: Zeina Merabi, Arij Dao
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The temporal order of information processing in the brain is an important code in many acoustic signals, including speech, music, and animal vocalizations. Despite its significance, surprisingly little is known about its underlying cellular mechanisms and network manifestations. In the songbird telencephalic nucleus HVC, a subset of neurons shows temporal combination sensitivity (TCS). These neurons show a high temporal specificity, responding differently to distinct patterns of spectral elements and their combinations. HVC neuron types include basal-ganglia-projecting HVCX, forebrain-projecting HVCRA, and interneurons (HVC¬INT), each exhibiting distinct cellular, electrophysiological and functional properties. In this work, we develop conductance-based neural network models connecting the different classes of HVC neurons via different wiring scenarios, aiming to explore possible neural mechanisms that orchestrate the combination sensitivity property exhibited by HVCX, as well as replicating in vivo firing patterns observed when TCS neurons are presented with various auditory stimuli. The ionic and synaptic currents for each class of neurons that are presented in our networks and are based on pharmacological studies, rendering our networks biologically plausible. We present for the first time several realistic scenarios in which the different types of HVC neurons can interact to produce this behavior. The different networks highlight neural mechanisms that could potentially help to explain some aspects of combination sensitivity, including 1) interplay between inhibitory interneurons’ activity and the post inhibitory firing of the HVCX neurons enabled by T-type Ca2+ and H currents, 2) temporal summation of synaptic inputs at the TCS site of opposing signals that are time-and frequency- dependent, and 3) reciprocal inhibitory and excitatory loops as a potent mechanism to encode information over many milliseconds. The result is a plausible network model characterizing auditory processing in HVC. Our next step is to test the predictions of the model.Keywords: combination sensitivity, songbirds, neural networks, spatiotemporal integration
Procedia PDF Downloads 554159 Form-Finding of Tensioned Fabric Structure in Mathematical Monkey Saddle Model
Authors: Yee Hooi Min, Abdul Hadi, M. N., A. G. Kay Dora
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Form-finding has to be carried out for tensioned fabric structure in order to determine the initial equilibrium shape under prescribed support condition and pre-stress pattern. Tensioned fabric structures are normally designed to be in the form of equal tensioned surface. Tensioned fabric structure is highly suited to be used for realizing surfaces of complex or new forms. However, research study on a new form as a tensioned fabric structure has not attracted much attention. Another source of inspiration minimal surface which could be adopted as form for tensioned fabric structure is very crucial. The aim of this study is to propose initial equilibrium shape of tensioned fabric structures in the form of Monkey Saddle. Computational form-finding is frequently used to determine the possible form of uniformly stressed surfaces. A tensioned fabric structure must curve equally in opposite directions to give the resulting surface a three dimensional stability. In an anticlastic doubly curved surface, the sum of all positive and all negative curvatures is zero. This study provides an alternative choice for structural designer to consider the Monkey Saddle applied in tensioned fabric structures. The results on factors affecting initial equilibrium shape can serve as a reference for proper selection of surface parameter for achieving a structurally viable surface. Such in-sight will lead to improvement of rural basic infrastructure, economic gains, sustainability of built environment and green technology initiative.Keywords: anticlastic, curvatures, form-finding, initial equilibrium shape, minimal surface, tensioned fabric structure
Procedia PDF Downloads 5274158 Complex Rigid-Plastic Deformation Model of Tow Degree of Freedom Mechanical System under Impulsive Force
Authors: Abdelouaheb Rouabhi
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In order to study the plastic resource of structures, the elastic-plastic single degree of freedom model described by Prandtl diagram is widely used. The generalization of this model to tow degree of freedom beyond the scope of a simple rigid-plastic system allows investigating the plastic resource of structures under complex disproportionate by individual components of deformation (earthquake). This macro-model greatly increases the accuracy of the calculations carried out. At the same time, the implementation of the proposed macro-model calculations easier than the detailed dynamic elastic-plastic calculations existing software systems such as ANSYS.Keywords: elastic-plastic, single degree of freedom model, rigid-plastic system, plastic resource, complex plastic deformation, macro-model
Procedia PDF Downloads 3754157 Collocation Errors Made by Saudi Learners of English
Authors: Pakenam Shiha, Nadine Lacsina
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Systematic and in-depth analysis of ESL learners’ lexical errors, in general, and of collocation errors, in particular, are relatively rare. Analysis as such proves crucial in understanding how ESL learners construct and use these fixed expressions. Collocational competence of ESL learners is necessary for achieving a native-like proficiency level, which is one of the objectives of foundation programs. This study aims to examine the collocational competence of 50 Saudi foundation program students and identify the collocation errors that they often make. Furthermore, using a questionnaire, the challenges that students encounter in learning collocations and the ways in which their L1 affects their ability to recognize these expressions are identified. To identify the lexical errors and the collocational competence of the students a collocation test was administered. The 150-item lexical collocation test consists of verb-noun and adjective-noun structures. Results of the study reveal that there is a significant difference between the scores of students in the verb-noun and adjective-noun structures. The majority of errors were recorded in the adjective-noun structures due to the students’ L1 influence on the English collocations and the inability to distinguish between synonyms. Moreover, some challenges that students encountered were problems in translation, non-exposure to certain collocations, and degree of L1-L2 difference. All in all, the findings of this study can be interpreted in relation to the student's proficiency level and L2 instruction. Other findings of the study provide insights into language pedagogy—specifically strategies to help students learn collocations more effectively.Keywords: collocations, ESL, applied linguistics, lexical collocations
Procedia PDF Downloads 1124156 Application of Gold Nanorods in Cancer Photothermaltherapy
Authors: Mehrnaz Mostafavi
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Lung cancer is one of the most harmful forms of cancer. The long-term survival rate of lung cancer patients treated by conventional modalities such as surgical resection, radiation, and chemotherapy remains far from satisfactory. Systemic drug delivery is rarely successful because only a limited amount of the chemotherapeutic drug targets lung tumor sites, even when administered at a high dose. Targeted delivery of drug molecules to organs or special sites is one of the most challenging research areas in pharmaceutical sciences. By developing colloidal delivery systems such as liposomes, micelles and nanoparticles a new frontier was opened for improving drug delivery. Nanoparticles with their special characteristics such as small particle size, large surface area and the capability of changing their surface properties have numerous advantages compared with other delivery systems. Targeted nanoparticle delivery to the lungs is an emerging area of interest.Multimodal or combination therapy represents a promising new method to fight disease. Therefore, a combination of different therapeutic strategies may be the best alternative to improve treatment outcomes for lung cancer. Photothermal therapy was proposed as a novel approach to treatment. In this work, photothermal therapy with gold nanoparticles and near infrared laser (NIR) irradiation was investigated.Four types of small (<100nm), NIR absorbing gold nanoparticles (nanospheres, nanorods) were synthesized using wet chemical methods and characterized by transmission electron microscopy, dynamic light scattering and UV-vis spectroscopy. Their synthesis and properties were evaluated, to determine their feasibility as a photothermal agent for clinical applications. In vitro cellular uptake studies of the nanoparticles into lung cancer cell lines was measured using light scattering microscopy.Small gold nanorods had good photothermal properties and the greatest cellular uptake, and were used in photothermal studies. Under 4W laser irradiation, an increase in temperature of 10°C and decrease in cell viability of up to 80% were obtained.Keywords: photothermal, therapy, cancer, gold nanorods
Procedia PDF Downloads 2384155 Effect of Column Stiffness and Orientation on Seismic Behaviour of Buildings with Vertical Irregularities
Authors: Saraswati Verma, Ankit Batra
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In the modern day, structures are designed with a lot of complexities due to economical, aesthetical, and functional needs causing various levels of irregularities to be induced. In the past, several studies have repeatedly shown that irregular structures suffer more damage than regular structures during earthquakes. The present study makes an effort to study the contribution of the orientation of columns in the seismic behaviour of buildings with vertical irregularities namely, soft storey irregularity, mass irregularity and geometric irregularity. The response of the various models is analysed using sap2000 version 14. The parameters through which a comparative response is investigated are displacement, variation in the stiffness contribution, and inter-storey drift. Models with different configurations of column orientations were studied for each vertical irregularity and it was observed that column orientation contributed significantly in affecting a better seismic response. Square columns of the same cross-sectional area showed a good response as compared to that of rectangular columns. The study concludes that as displacement values for buildings with a soft storey and mass irregularity are very high, square columns could be used to minimise the effect of displacement in x and y-axis. In buildings with geometric irregularity, exterior column orientations can be played with to enhance the stiffness in the shorter direction to control the displacement and drift values in both x and y directions.Keywords: soft storey, mass irregularity, geometric irregularity, column orientation, square column
Procedia PDF Downloads 3704154 Comparison of Spiral Circular Coil and Helical Coil Structures for Wireless Power Transfer System
Authors: Zhang Kehan, Du Luona
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Wireless power transfer (WPT) systems have been widely investigated for advantages of convenience and safety compared to traditional plug-in charging systems. The research contents include impedance matching, circuit topology, transfer distance et al. for improving the efficiency of WPT system, which is a decisive factor in the practical application. What is more, coil structures such as spiral circular coil and helical coil with variable distance between two turns also have indispensable effects on the efficiency of WPT systems. This paper compares the efficiency of WPT systems utilizing spiral or helical coil with variable distance between two turns, and experimental results show that efficiency of spiral circular coil with an optimum distance between two turns is the highest. According to efficiency formula of resonant WPT system with series-series topology, we introduce M²/R₋₁ to measure the efficiency of spiral circular coil and helical coil WPT system. If the distance between two turns s is too close, proximity effect theory shows that the induced current in the conductor, caused by a variable flux created by the current flows in the skin of vicinity conductor, is the opposite direction of source current and has assignable impart on coil resistance. Thus in two coil structures, s affects coil resistance. At the same time, when the distance between primary and secondary coils is not variable, s can also make the influence on M to some degrees. The aforementioned study proves that s plays an indispensable role in changing M²/R₋₁ and then can be adjusted to find the optimum value with which WPT system achieves the highest efficiency. In actual application situations of WPT systems especially in underwater vehicles, miniaturization is one vital issue in designing WPT system structures. Limited by system size, the largest external radius of spiral circular coil is 100 mm, and the largest height of helical coil is 40 mm. In other words, the turn of coil N changes with s. In spiral circular and helical structures, the distance between each two turns in secondary coil is set as a constant value 1 mm to guarantee that the R2 is not variable. Based on the analysis above, we set up spiral circular coil and helical coil model using COMSOL to analyze the value of M²/R₋₁ when the distance between each two turns in primary coil sp varies from 0 mm to 10 mm. In the two structure models, the distance between primary and secondary coils is 50 mm and wire diameter is chosen as 1.5 mm. The turn of coil in secondary coil are 27 in helical coil model and 20 in spiral circular coil model. The best value of s in helical coil structure and spiral circular coil structure are 1 mm and 2 mm respectively, in which the value of M²/R₋₁ is the largest. It is obviously to select spiral circular coil as the first choice to design the WPT system for that the value of M²/R₋₁ in spiral circular coil is larger than that in helical coil under the same condition.Keywords: distance between two turns, helical coil, spiral circular coil, wireless power transfer
Procedia PDF Downloads 3364153 Targeting the EphA2 Receptor Tyrosine Kinases in Melanoma Cancer, both in Humans and Dogs
Authors: Shabnam Abdi, Behzad Toosi
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Background: Melanoma is the most lethal type of malignant skin cancer in humans and dogs since it spreads rapidly throughout the body. Despite significant advances in treatment, cancer at an advanced stage has a poor prognosis. Hence, more effective treatments are needed to enhance outcomes with fewer side effects. Erythropoietin-producing hepatocellular receptors are the largest family of receptor tyrosine kinases and are divided into two subfamilies, EphA and EphB, both of which play a significant role in disease, especially cancer. Due to their association with proliferation and invasion in many aggressive types of cancer, Eph receptor tyrosine kinases (Eph RTKs) are promising cancer therapy molecules. Because these receptors have not been studied in canine melanoma, we investigated how EphA2 influences survival and tumorigenicity of melanoma cells. Methods: Expression of EphA2 protein in canine melanoma cell lines and human melanoma cell line was evaluated by Western blot. Melanoma cells were transduced with lentiviral particles encoding Eph-targeting shRNAs or non-silencing shRNAs (control) for silencing the expression of EphA2 receptor, and silencing was confirmed by Western blotting and immunofluorescence. The effect of siRNA treatment on cellular proliferation, colony formation, tumorsphere assay, invasion was analyzed by Resazurin assay Matrigel invasion assay, respectively. Results: Expression of EphA2 was detected in canine and human melanoma cell lines. Moreover, stably silencing EphA2 by specific shRNAs significantly and consistently decreased the expression of EphA2 protein in both human and canine melanoma cells. Proliferation, colony formation, tumorsphere and invasion of melanoma cells were significantly decreased in EphA2 siRNA-treated cells compared to control. Conclusion: Our data provide the first functional evidence that the EphA2 receptor plays a critical role in the malignant cellular behavior of melanoma in both human and dogs.Keywords: ephA2, targeting, melanoma, human, canine
Procedia PDF Downloads 514152 Research of the Activation Energy of Conductivity in P-I-N SiC Structures Fabricated by Doping with Aluminum Using the Low-Temperature Diffusion Method
Authors: Ilkham Gafurovich Atabaev, Khimmatali Nomozovich Juraev
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The activation energy of conductivity in p-i-n SiC structures fabricated by doping with Aluminum using the new low-temperature diffusion method is investigated. In this method, diffusion is stimulated by the flux of carbon and silicon vacancies created by surface oxidation. The activation energy of conductivity in the p - layer is 0.25 eV and it is close to the ionization energy of Aluminum in 4H-SiC from 0.21 to 0.27 eV for the hexagonal and cubic positions of aluminum in the silicon sublattice for weakly doped crystals. The conductivity of the i-layer (measured in the reverse biased diode) shows 2 activation energies: 0.02 eV and 0.62 eV. Apparently, the 0.62 eV level is a deep trap level and it is a complex of Aluminum with a vacancy. According to the published data, an analogous level system (with activation energies of 0.05, 0.07, 0.09 and 0.67 eV) was observed in the ion Aluminum doped 4H-SiC samples.Keywords: activation energy, aluminum, low temperature diffusion, SiC
Procedia PDF Downloads 2684151 Efficient Neural and Fuzzy Models for the Identification of Dynamical Systems
Authors: Aouiche Abdelaziz, Soudani Mouhamed Salah, Aouiche El Moundhe
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The present paper addresses the utilization of Artificial Neural Networks (ANNs) and Fuzzy Inference Systems (FISs) for the identification and control of dynamical systems with some degree of uncertainty. Because ANNs and FISs have an inherent ability to approximate functions and to adapt to changes in input and parameters, they can be used to control systems too complex for linear controllers. In this work, we show how ANNs and FISs can be put in order to form nets that can learn from external data. In sequence, it is presented structures of inputs that can be used along with ANNs and FISs to model non-linear systems. Four systems were used to test the identification and control of the structures proposed. The results show the ANNs and FISs (Back Propagation Algorithm) used were efficient in modeling and controlling the non-linear plants.Keywords: non-linear systems, fuzzy set Models, neural network, control law
Procedia PDF Downloads 2014150 Investigating the Role of Combined Length Scale Effect on the Mechanical Properties of Ni/Cu Multilayer Structures
Authors: Naresh Radaliyagoda, Nigel M. Jennett, Rong Lan, David Parfitt
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A series of length scale engineered multilayer material with temperature robust mechanical properties has been suggested. A range of polycrystalline copper sub-layers with the thickness varying from 1 to 25μm and buried in between two nickel layers was produced using electrodeposition dual bath technique. The structure of the multilayers was characterized using Electron Backscatter Diffraction and Scanning Electron Microscope. The interface effect on the hardness and elastic modulus was tested using Nano-indentation. Results of the grain size and layer thickness measurements, and indentation hardness have been compared. It is found that there is a combined length scale effect that improves mechanical properties in Ni/Cu multilayer structures.Keywords: nano-indentation, size effect, multilayers, electrodeposition
Procedia PDF Downloads 1414149 Prediction of Pile-Raft Responses Induced by Adjacent Braced Excavation in Layered Soil
Authors: Linlong Mu, Maosong Huang
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Considering excavations in urban areas, the soil deformation induced by the excavations usually causes damage to the surrounding structures. Displacement control becomes a critical indicator of foundation design in order to protect the surrounding structures. Evaluation, the damage potential of the surrounding structures induced by the excavations, usually depends on the finite element method (FEM) because of the complexity of the excavation and the variety of the surrounding structures. Besides, evaluation the influence of the excavation on surrounding structures is a three-dimensional problem. And it is now well recognized that small strain behaviour of the soil influences the responses of the excavation significantly. Three-dimensional FEM considering small strain behaviour of the soil is a very complex method, which is hard for engineers to use. Thus, it is important to obtain a simplified method for engineers to predict the influence of the excavations on the surrounding structures. Based on large-scale finite element calculation with small-strain based soil model coupling with inverse analysis, an empirical method is proposed to calculate the three-dimensional soil movement induced by braced excavation. The empirical method is able to capture the small-strain behaviour of the soil. And it is suitable to be used in layered soil. Then the free-field soil movement is applied to the pile to calculate the responses of the pile in both vertical and horizontal directions. The asymmetric solutions for problems in layered elastic half-space are employed to solve the interactions between soil points. Both vertical and horizontal pile responses are solved through finite difference method based on elastic theory. Interactions among the nodes along a single pile, pile-pile interactions, pile-soil-pile interaction action and soil-soil interactions are counted to improve the calculation accuracy of the method. For passive piles, the shadow effects are also calculated in the method. Finally, the restrictions of the raft on the piles and the soils are summarized as: (1) the summations of the internal forces between the elements of the raft and the elements of the foundation, including piles and soil surface elements, is equal to 0; (2) the deformations of pile heads or of the soil surface elements are the same as the deformations of the corresponding elements of the raft. Validations are carried out by comparing the results from the proposed method with the results from the model tests, FEM and other existing literatures. From the comparisons, it can be seen that the results from the proposed method fit with the results from other methods very well. The method proposed herein is suitable to predict the responses of the pile-raft foundation induced by braced excavation in layered soil in both vertical and horizontal directions when the deformation is small. However, more data is needed to verify the method before it can be used in practice.Keywords: excavation, pile-raft foundation, passive piles, deformation control, soil movement
Procedia PDF Downloads 2224148 Assessing the Implementation of Community Driven Development through Social Capital in Migrant and Indigenous Informal Settlements in Accra, Ghana
Authors: Beatrice Eyram Afi Ziorklui, Norihisa Shima
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Community Driven Development (CDD) is now a widely recommended and accepted development strategy for informal communities across the continent. Centered on the utilization of social capital through community structures, different informal settlements have different structures and different levels of social capital, which affect the implementation and ability to overcome CDD challenges. Although known to be very successful, there are few perspectives on the implementation of CDD initiatives in different informal settlements. This study assesses the implementation of CDD initiatives in migrant and indigenous informal settlements and their ability to navigate challenges. The case study research design was adopted in this research, and respondents were chosen through simple random sampling. Using the Statistical Package for social scientists (SPSS) for data analysis, the study found that migrant informal settlements implement CDD projects through the network of hierarchical structures based on government systems, whereas indigenous informal settlements implement through the hierarchical social structure based on traditions and culture. The study also found that, with the exception of the challenge of land accessibility in migrant informal settlements, all other challenges, such as participation, resource mobilization, and maintenance, have a significant relationship with social capital, although indigenous informal settlements have higher levels of social capital than migrant informal settlements. The study recommends a framework that incorporates community characteristics and the underlying social capital to facilitate upgrading strategies in informal in Ghana.Keywords: community driven development, informal settlements, social capital, upgrading
Procedia PDF Downloads 874147 Development of PVA/polypyrrole Scaffolds by Supercritical CO₂ for Its Application in Biomedicine
Authors: Antonio Montes, Antonio Cozar, Clara Pereyra, Diego Valor, Enrique Martinez de la Ossa
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Tissues and organs can be damaged because of traumatism, congenital illnesses, or cancer and the traditional therapeutic alternatives, such as surgery, cannot usually completely repair the damaged tissues. Tissue engineering allows regeneration of the patient's tissues, reducing the problems caused by the traditional methods. Scaffolds, polymeric structures with interconnected porosity, can be promoted the proliferation and adhesion of the patient’s cells in the damaged area. Furthermore, by means of impregnation of the scaffold with beneficial active substances, tissue regeneration can be induced through a drug delivery process. The objective of the work is the fabrication of a PVA scaffold coated with Gallic Acid and polypyrrole through a one-step foaming and impregnation process using the SSI technique (Supercritical Solvent Impregnation). In this technique, supercritical CO₂ penetrates into the polymer chains producing the plasticization of the polymer. In the depressurization step a CO₂ cellular nucleation and growing to take place to an interconnected porous structure of the polymer. The foaming process using supercritical CO₂ as solvent and expansion agent presents advantages compared to the traditional scaffolds’ fabrication methods, such as the polymer’s high solubility in the solvent or the possibility of carrying out the process at a low temperature, avoiding the inactivation of the active substance. In this sense, the supercritical CO₂ avoids the use of organic solvents and reduces the solvent residues in the final product. Moreover, this process does not require long processing time that could cause the stratification of substance inside the scaffold reducing the therapeutic efficiency of the formulation. An experimental design has been carried out to optimize the SSI technique operating conditions, as well as a study of the morphological characteristics of the scaffold for its use in tissue engineerings, such as porosity, conductivity or the release profiles of the active substance. It has been proved that the obtained scaffolds are partially porous, conductors of electricity and are able to release Gallic Acid in the long term.Keywords: scaffold, foaming, supercritical, PVA, polypyrrole, gallic acid
Procedia PDF Downloads 1734146 Leadership Succession and Renewal in Zimbabwe Political Parties: A Critical Analysis of the Bhora Remusango Concept
Authors: A. F. Chikerema
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Political leadership in Africa vary from the “criminalization” of the state to political leadership as “dispensing patrimony”, the “recycling” of elites and the use of state power and resources to consolidate political and economic power (Van Wyk:2007: p1). Political parties just like any other organizations always need leadership renewal and revamping, besides ideological and policy renewal. Zimbabwean politics present a shunned leadership renewal as reflected by the two champion political parties namely ZANU PF and MDC-T. Despite hot political power contestation between MDC and ZANUPF, the parties` internal structures are hinged on the two Godfather or Father figure that is Mugabe and Tsvangirai. They are the “labels “behind the two political parties. The suppressing of dissent voice on succession and renewal of leadership in the two parties has brew resistance from within and this has resulted in factional fights within the two political parties. The disgruntlement in the political parties has led to the stemming of the ‘bhoramusango concept’ from the electorate and party cadres whereby they are throwing or donating away their votes to other political parties. The ‘bhoramusango’ concept haunted ZANUPF in 2008 leading to its defeat by the opposition MDC-T .The paper takes the form of an analytic approach on leadership crisis in Zimbabwe. The narrative is framed on key concepts of leadership: namely leadership renewal and leadership succession, as agents operating within inherited structures negotiated political settlements, and form structures of leadership. Rulers gave priority to the consolidation of state power by installing party loyalists in the armed forces, civil service and local government. As part of this process, rulers have ensured consolidated power and authority.Keywords: leadership renewal, leadership succession, ‘Bhora Musango’, political culture, political legitimacy
Procedia PDF Downloads 4024145 Air Flows along Perforated Metal Plates with the Heat Transfer
Authors: Karel Frana, Sylvio Simon
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The objective of the paper is a numerical study of heat transfer between perforated metal plates and the surrounding air flows. Different perforation structures can nowadays be found in various industrial products. Besides improving the mechanical properties, the perforations can intensify the heat transfer as well. The heat transfer coefficient depends on a wide range of parameters such as type of perforation, size, shape, flow properties of the surrounding air etc. The paper was focused on three different perforation structures which have been investigated from the point of the view of the production in the previous studies. To determine the heat coefficients and the Nusselt numbers, the numerical simulation approach was adopted. The calculations were performed using the OpenFOAM software. The three-dimensional, unstable, turbulent and incompressible air flow around the perforated surface metal plate was considered.Keywords: perforations, convective heat transfers, turbulent flows, numerical simulations
Procedia PDF Downloads 5704144 Morphological Transformations and Variations in Architectural Language from Tombs to Mausoleums: From Ottoman Empire to the Turkish Republic
Authors: Uğur Tuztaşi, Mehmet Uysal, Yavuz Arat
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The tomb (grave) structures that have influenced the architectural culture from the Seljuk times to the Ottoman throughout Anatolia are members of a continuing building tradition in terms of monumental expression and styles. This building typology which has religious and cultural permeability in view of spatial traces and structural formations follows the entire trajectory of the respect to death and the deceased from the Seljuks to the Ottomans and also the changing burial traditions epitomised in the form of mausoleums in the Turkish Republic. Although the cultural layers have the same contents with regards to the cult of monument this architectural tradition which evolved from tombs to mausoleums changed in both typological formation and structural size. In short, the tomb tradition with unique examples of architectural functions and typological formations has been encountered from 13th century onwards and continued during the Ottoman period with changes in form and has transformed to mausoleums during the 20th century. This study analyses the process of transformation from complex structures to simple structures and then to monumental graves in terms of architectural expression. Moreover, the study interrogates the architectural language of Anatolian Seljuk tombs to Ottoman tombs and monumental graves built during the republican period in terms of spatial and structural contexts.Keywords: death and space in Turks, monumental graves, language of architectural style, morphological transformations
Procedia PDF Downloads 3514143 Simplifying Seismic Vulnerability Analysis for Existing Reinforced Concrete Buildings
Authors: Maryam Solgi, Behzad Shahmohammadi, Morteza Raissi Dehkordi
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One of the main steps for seismic retrofitting of buildings is to determine the vulnerability of structures. While current procedures for evaluating existing buildings are complicated, and there is no limitation between short, middle-high, and tall buildings. This research utilizes a simplified method for assessing structures, which is adequate for existing reinforced concrete buildings. To approach this aim, Simple Lateral Mechanisms Analysis (SLaMA) procedure proposed by NZSEE (New Zealand Society for Earthquake Engineering) has been carried out. In this study, three RC moment-resisting frame buildings are determined. First, these buildings have been evaluated by inelastic static procedure (Pushover) based on acceptance criteria. Then, Park-Ang Damage Index is determined for the whole members of each building by Inelastic Time History Analysis. Next, the Simple Lateral Mechanisms Analysis procedure, a hand method, is carried out to define the capacity of structures. Ultimately, existing procedures are compared with Peak Ground Acceleration caused to fail (PGAfail). The results of this comparison emphasize that the Pushover procedure and SLaMA method define a greater value of PGAfail than the Park-Ang Damage model.Keywords: peak ground acceleration caused to fail, reinforced concrete moment-frame buildings, seismic vulnerability analysis, simple lateral mechanisms analysis
Procedia PDF Downloads 854142 Applications of Engineering Geology in Hydro Power Tunnel Projects in Himalayan Geological Regime
Authors: Rameh Chauhan
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Tunnel construction in Himalayan rock is a challenging task due to fragile nature of the strata. Tunnel excavation carried out from lower Himalayas to high Himalayas in different metamorphic rock. Therefore application of engineering geology plays a vital role during various stage of the tunneling projects. Engineering geology is defined as application of geology to construction of civil structures through engineering practice. It is applied to the design, construction and performance aspects of engineering structure on the surface or sub-surface like dam, underground and surface power house, cut slopes, tunnels and underground storage cavern for nuclear material. But this paper emphasized mostly on underground structures like big caverns of Power house, desilting chambers, and tunnels of various sizes. Construction of these structures in the fragile rock conditions of Himalayan geology from Western Himalayas to Eastern Himalayas necessitated the application of the engineering geology on the micro-scale base for the stability, performance, and longevity of the civil structures. Number of hydropower projects have been constructed, some of them are under construction and under investigation stage. These projects are located in various parts of Himalayas under various seismic-tectonic zones. Tunneling works are involved in these projects. This paper represents the various engineering geological practices adopted in investigation and construction stage of various projects based on experiences gained during past construction histories in Himalayan geology of young mountains in very fragile geological conditions. Highlighting and sharing of use of these techniques on various platforms will definitely enhance the knowledge for carrying out the construction of various projects for the development of society. Construction of the tunnels, surface, and sub-surface caverns, dams, highway, metro, highway tunnels are all based on engineering geological parameters in combinations with other engineering considerations.Keywords: cavern-power house, desilting chambers and tunnels, seismic-tectonic-zones, earthquake-prone zones based on intensities
Procedia PDF Downloads 2184141 Micromechanical Compatibility Between Cells and Scaffold Mediates the Efficacy of Regenerative Medicine
Authors: Li Yang, Yang Song, Martin Y. M. Chiang
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Objective: To experimentally substantiate the micromechanical compatibility between cell and scaffold, in the regenerative medicine approach for restoring bone volume, is essential for phenotypic transitions Methods: Through nanotechnology and electrospinning process, nanofibrous scaffolds were fabricated to host dental follicle stem cells (DFSCs). Blends (50:50) of polycaprolactone (PCL) and silk fibroin (SF), mixed with various content of cellulose nanocrystals (CNC, up to 5% in weight), were electrospun to prepare nanofibrous scaffolds with heterogeneous microstructure in terms of fiber size. Colloidal probe atomic force microscopy (AFM) and conventional uniaxial tensile tests measured the scaffold stiffness at the micro-and macro-scale, respectively. The cell elastic modulus and cell-scaffold adhesive interaction (i.e., a chemical function) were examined through single-cell force spectroscopy using AFM. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to determine if the mechanotransduction signal (i.e., Yap1, Wwr2, Rac1, MAPK8, Ptk2 and Wnt5a) is upregulated by the scaffold stiffness at the micro-scale (cellular scale). Results: The presence of CNC produces fibrous scaffolds with a bimodal distribution of fiber diameter. This structural heterogeneity, which is CNC-composition dependent, remarkably modulates the mechanical functionality of scaffolds at microscale and macroscale simultaneously, but not the chemical functionality (i.e., only a single material property is varied). In in vitro tests, the osteogenic differentiation and gene expression associated with mechano-sensitive cell markers correlate to the degree of micromechanical compatibility between DFSCs and the scaffold. Conclusion: Cells require compliant scaffolds to encourage energetically favorable interactions for mechanotransduction, which are converted into changes in cellular biochemistry to direct the phenotypic evolution. The micromechanical compatibility is indeed important to the efficacy of regenerative medicine.Keywords: phenotype transition, scaffold stiffness, electrospinning, cellulose nanocrystals, single-cell force spectroscopy
Procedia PDF Downloads 1744140 Microfluidic Construction of Responsive Photonic Microcapsules for Microsensors
Authors: Lingling Shui, Shuting Xie
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As alternatives to electronic devices, optically active structures from responsive nanomaterials offer great opportunity buildup smart functional sensors. Hereby, we report on droplet microfluidics enabled construction and application of photonic microcapsules (PMCs) for colorimetric temperature microsensors, enabling miniaturization for injectable local micro-area sensing and integration for large-area sensing. Monodispersed PMCs are produced by in-situ photopolymerization of hydrogel shells of cholesteric liquid crystal (CLC)-in-water-in-oil double emulsion droplets prepared using microfluidic devices, with controllable physical structures and chemical compositions. Constructed PMCs exhibit thermal responsive structural color according to the selective Bragg reflection of CLC’s periodical helical structures within the microdroplet’s spherical confinement. Constructed PMCs with tunable size and composition have been successfully applied for monitoring the living cell extracellular temperature via co-incubation with cell suspension, and for detecting human body temperature via a flexible device from assembled PMCs. These PMCs could be flexibly applied in either micro-environment or large-area surface, enabling wide applications for precision temperature monitoring biological activities (e.g. cells or organs), optoelectronic devices working conditions (e.g. temperature indicators under extreme conditions), and etc.Keywords: droplet, microfluidics, assembly, soft materials, microsensor
Procedia PDF Downloads 744139 Modelling the Effects of External Factors Affecting Concrete Carbonation
Authors: Abhishek Mangal, Kunal Tongaria, S. Mandal, Devendra Mohan
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Carbonation of reinforced concrete structures has emerged as one of the major challenges for Civil engineers across the world. With increasing emissions from various activities, carbon dioxide concentration in the atmosphere has been eve rising, enhancing its penetration in porous concrete, reaching steel bars and ultimately leading to premature failure. Several literatures have been published dealing with the various interdependent variables related to carbonation. However, with innumerable variability a generalization of these data proves to be a troublesome task. This paper looks into this carbonation anomaly in concrete structures caused by various external variables such as relative humidity, concentration of CO2, curing period and ambient temperature. Significant discussions and comparisons have been presented on the basis of various studies conducted with an aim to predict the depth of carbonation as a function of these multidimensional parameters using various numerical and statistical modelling techniques.Keywords: carbonation, curing, exposure conditions, relative humidity
Procedia PDF Downloads 2484138 Three Dimensional Numerical Analysis for Longitudinal Seismic Response of Tunnels under Asynchronous Earthquake
Authors: Peng Li, Er-xiang Song
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Numerical analysis of longitudinal tunnel seismic response due to spatial variation of earthquake ground motion is an important issue that cannot be ignored in the design and safety evaluation of tunnel structures. In this paper, numerical methods for analysis of tunnel longitudinal response under asynchronous seismic wave is extensively studied, including the improvement of the 1D time-domain finite element method, three dimensional numerical simulation technique for the site asynchronous earthquake response as well as the 3-D soil-tunnel structure interaction analysis. The study outcome will be beneficial to aid further research on the nonlinear meticulous numerical analysis and seismic response mechanism of tunnel structures under asynchronous earthquake motion.Keywords: asynchronous input, longitudinal seismic response, tunnel structure, numerical simulation, traveling wave effect
Procedia PDF Downloads 4294137 Ultra High Performance Concrete Using Special Aggregates for Irregular Structures (the New Concrete Technology)
Authors: Arjun, A. D. Singh
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Concrete the basic material using in construction across the global these days. The purpose of this special concrete is to provide extra strength and stability for irregular structure where the center of gravity is disturbed. In this paper an effort has been made to use different type of material aggregates has been discussed. We named As "STAR Aggregates" which has qualities to resist Shear, tension and compression forces. We have been divided into coarse aggregates and fine aggregates according to their sizes. Star Aggregates has interlocking behavior and cutting edge technology. Star aggregates had been draft and deign in Auto CAD and then analysis in ANSYS software. by using special aggregates we deign concrete grade of M40 for mega structures and irregular structure. This special concrete with STAR aggregates use in construction for irregular structure like Bridges, Skyscrapers or in deigned buildings.Keywords: star aggregates, high performance concrete, material aggregates, interlocking
Procedia PDF Downloads 5574136 Feedback Matrix Approach for Relativistic Runaway Electron Avalanches Dynamics in Complex Electric Field Structures
Authors: Egor Stadnichuk
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Relativistic runaway electron avalanches (RREA) are a widely accepted source of thunderstorm gamma-radiation. In regions with huge electric field strength, RREA can multiply via relativistic feedback. The relativistic feedback is caused both by positron production and by runaway electron bremsstrahlung gamma-rays reversal. In complex multilayer thunderstorm electric field structures, an additional reactor feedback mechanism appears due to gamma-ray exchange between separate strong electric field regions with different electric field directions. The study of this reactor mechanism in conjunction with the relativistic feedback with Monte Carlo simulations or by direct solution of the kinetic Boltzmann equation requires a significant amount of computational time. In this work, a theoretical approach to study feedback mechanisms in RREA physics is developed. It is based on the matrix of feedback operators construction. With the feedback matrix, the problem of the dynamics of avalanches in complex electric structures is reduced to the problem of finding eigenvectors and eigenvalues. A method of matrix elements calculation is proposed. The proposed concept was used to study the dynamics of RREAs in multilayer thunderclouds.Keywords: terrestrial Gamma-ray flashes, thunderstorm ground enhancement, relativistic runaway electron avalanches, gamma-rays, high-energy atmospheric physics, TGF, TGE, thunderstorm, relativistic feedback, reactor feedback, reactor model
Procedia PDF Downloads 1584135 Natural Frequency Analysis of Small-Scale Arch Structure by Shaking Table Test
Authors: Gee-Cheol Kim, Joo-Won Kang
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Structural characteristics of spatial structure are different from that of rahmen structures and it has many factors that are unpredictable experientially. Both horizontal and vertical earthquake should be considered because of seismic behaviour characteristics of spatial structures. This experimental study is conducted about seismic response characteristics of roof structure according to the effect of columns or walls, through scale model of arch structure that has the basic dynamic characteristics of spatial structure. Though remarkable response is not occurred for horizontal direction in the region of higher frequency than the region of frequency that seismic energy is concentrated, relatively large response is occurred in vertical direction. It is proved that seismic response of arch structure with column is varied according to property of column.Keywords: arch structure, seismic response, shaking table, spatial structure
Procedia PDF Downloads 3554134 Behaviour of Reinforced Concrete Infilled Frames under Seismic Loads
Authors: W. Badla
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A significant portion of the buildings constructed in Algeria is structural frames with infill panels which are usually considered as non structural components and are neglected in the analysis. However, these masonry panels tend to influence the structural response. Thus, these structures can be regarded as seismic risk buildings, although in the Algerian seismic code there is little guidance on the seismic evaluation of infilled frame buildings. In this study, three RC frames with 2, 4, and 8 story and subjected to three recorded Algerian accelerograms are studied. The diagonal strut approach is adopted for modeling the infill panels and a fiber model is used to model RC members. This paper reports on the seismic evaluation of RC frames with brick infill panels. The results obtained show that the masonry panels enhance the load lateral capacity of the buildings and the infill panel configuration influences the response of the structures.Keywords: seismic design, RC frames, infill panels, non linear dynamic analysis
Procedia PDF Downloads 5394133 Investigation of Flexural – Torsion Instability of Struts Using Modified Newmark Method
Authors: Seyed Amin Vakili, Sahar Sadat Vakili, Seyed Ehsan Vakili, Nader Abdoli Yazdi
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Differential equations are of fundamental importance in engineering and applied mathematics, since many physical laws and relations appear mathematically in the form of such equations. The equilibrium state of structures consisting of one-dimensional elements can be described by an ordinary differential equation. The response of these kinds of structures under the loading, namely relationship between the displacement field and loading field, can be predicted by the solution of these differential equations and on satisfying the given boundary conditions. When the effect of change of geometry under loading is taken into account in modeling of equilibrium state, then these differential equations are partially integrable in quartered. They also exhibit instability characteristics when the structures are loaded compressively. The purpose of this paper is to represent the ability of the Modified Newmark Method in analyzing flexural-torsional instability of struts for both bifurcation and non-bifurcation structural systems. The results are shown to be very accurate with only a small number of iterations. The method is easily programmed, and has the advantages of simplicity and speeds of convergence and easily is extended to treat material and geometric nonlinearity including no prismatic members and linear and nonlinear spring restraints that would be encountered in frames. In this paper, these abilities of the method will be extended to the system of linear differential equations that govern strut flexural torsional stability.Keywords: instability, torsion, flexural, buckling, modified newmark method stability
Procedia PDF Downloads 3454132 Investigation of Water Absorption and Compressive Strength of Resin Coated Mortar
Authors: Yasir Ali, Zain Ul Abdin, Muhammad Wisal Khattak
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Nowadays various advanced techniques are used to enhance the performance of materials in the field of construction engineering. Structures exposed to an aggressive, humid and hostile environment are experiencing severe negative impacts which lead to premature failure. Polyester resin is one of the advanced material used for improving performance of structural materials especially for repair/ refurbish purpose of structures and protection from contaminated environmental effect/ hazards. This study investigated the aptness of the polyester resin as coating agent on the mortar and assessed its performance in an ambient environment of Pakistan. Cubical specimens of mortar were fabricated. These specimens were tested for water absorption and compressive strength after one day and sixty days. These tests were performed under different exposure conditions (ambient environment and submerged in water). The specimens were coated with one, two and three layers and results were compared to control (no/ zero resin layer) specimens. Test results indicated that there is a significant decrease in water absorption of mortar coated with resin when compared to controlled specimens. The compressive strength test results revealed that resin coated specimen had higher strength when compared to controlled specimens. The results suggested that resin is a promising material and can be used effectively in structures which are exposed to high temperatures. The study would be helpful in improving performance of the structural material in a hazardous environment.Keywords: ambient environment, coating, mortar, polyester resin
Procedia PDF Downloads 3514131 Geotechnical Education in the USA: A Comparative Analysis of Academic Schooling vs. Industry Needs in the Area of Earth Retaining Structures
Authors: Anne Lemnitzer, Eric Tavarez
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The academic rigor of the geotechnical engineering curriculum indicates strong institutional and geographical variations. Geotechnical engineering deals with the most challenging civil engineering material, as opposed to structural engineering, environmental studies, transportation engineering, and water resources. Yet, technical expectations posed by the practicing professional community do not necessarily consider the challenges inherent to the disparity in academic rigor and disciplinary differences. To recognize the skill shortages among current graduates as well as identify opportunities to better equip graduate students in specific fields of geotechnical engineering, a two-part survey was developed in collaboration with the Earth Retaining Structures (ERS) Committee of the American Society of Civil Engineers. Earth Retaining Structures are critical components of infrastructure systems and integral components to many major engineering projects. Within the geotechnical curriculum, Earth Retaining Structures is either taught as a separate course or major subject within a foundation design class. Part 1 of the survey investigated the breadth and depth of the curriculum with respect to ERS by requesting faculty across the United States to provide data on their curricular content, integration of practice-oriented course content, student preparation for professional licensing, and level of technical competency expected upon student graduation. Part 2 of the survey enables a comparison of training provided versus training needed. This second survey addressed practicing geotechnical engineers in all sectors of the profession (e.g., private engineering consulting, governmental agencies, contractors, suppliers/manufacturers) and collected data on the expectations with respect to technical and non-technical skills of engineering graduates entering the professional workforce. Results identified skill shortages in soft skills, critical thinking, analytical and language skills, familiarity with design codes and standards, and communication with various stakeholders. The data will be used to develop educational tools to advance the proficiency and expertise of geotechnical engineering students to meet and exceed the expectations of the profession and to stimulate a lifelong interest in advancing the field of geotechnical engineering.Keywords: geotechnical engineering, academic training, industry requirements, earth retaining structures
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