Search results for: shear wall frame
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 3246

Search results for: shear wall frame

1746 Spatial Direct Numerical Simulation of Instability Waves in Hypersonic Boundary Layers

Authors: Jayahar Sivasubramanian

Abstract:

Understanding laminar-turbulent transition process in hyper-sonic boundary layers is crucial for designing viable high speed flight vehicles. The study of transition becomes particularly important in the high speed regime due to the effect of transition on aerodynamic performance and heat transfer. However, even after many years of research, the transition process in hyper-sonic boundary layers is still not understood. This lack of understanding of the physics of the transition process is a major impediment to the development of reliable transition prediction methods. Towards this end, spatial Direct Numerical Simulations are conducted to investigate the instability waves generated by a localized disturbance in a hyper-sonic flat plate boundary layer. In order to model a natural transition scenario, the boundary layer was forced by a short duration (localized) pulse through a hole on the surface of the flat plate. The pulse disturbance developed into a three-dimensional instability wave packet which consisted of a wide range of disturbance frequencies and wave numbers. First, the linear development of the wave packet was studied by forcing the flow with low amplitude (0.001% of the free-stream velocity). The dominant waves within the resulting wave packet were identified as two-dimensional second mode disturbance waves. Hence the wall-pressure disturbance spectrum exhibited a maximum at the span wise mode number k = 0. The spectrum broadened in downstream direction and the lower frequency first mode oblique waves were also identified in the spectrum. However, the peak amplitude remained at k = 0 which shifted to lower frequencies in the downstream direction. In order to investigate the nonlinear transition regime, the flow was forced with a higher amplitude disturbance (5% of the free-stream velocity). The developing wave packet grows linearly at first before reaching the nonlinear regime. The wall pressure disturbance spectrum confirmed that the wave packet developed linearly at first. The response of the flow to the high amplitude pulse disturbance indicated the presence of a fundamental resonance mechanism. Lower amplitude secondary peaks were also identified in the disturbance wave spectrum at approximately half the frequency of the high amplitude frequency band, which would be an indication of a sub-harmonic resonance mechanism. The disturbance spectrum indicates, however, that fundamental resonance is much stronger than sub-harmonic resonance.

Keywords: boundary layer, DNS, hyper sonic flow, instability waves, wave packet

Procedia PDF Downloads 183
1745 Finite Element Analysis of Rom Silo Subjected to 5000 Tons Monotic Loads at an Anonymous Mine in Zimbabwe

Authors: T. Mushiri, K. Tengende, C. Mbohwa, T. Garikayi

Abstract:

This paper introduces finite element analysis of Run off Mine (ROM) silo subjected to dynamic loading. The proposed procedure is based on the use of theoretical equations to come up with pressure and forces exerted by Platinum Group Metals (PGMs) ore to the silo wall. Finite Element Analysis of the silo involves the use of CAD software (AutoCAD) for3D creation and CAE software (T-FLEX) for the simulation work with an optimization routine to minimize the mass and also ensure structural stiffness and stability. In this research an efficient way to design and analysis of a silo in 3D T-FLEX (CAD) program was created the silo to stay within the constrains and so as to know the points of failure due dynamic loading.

Keywords: reinforced concrete silo, finite element analysis, T-FLEX software, AutoCAD

Procedia PDF Downloads 482
1744 Numerical Modeling of Various Support Systems to Stabilize Deep Excavations

Authors: M. Abdallah

Abstract:

Urban development requires deep excavations near buildings and other structures. Deep excavation has become more a necessity for better utilization of space as the population of the world has dramatically increased. In Lebanon, some urban areas are very crowded and lack spaces for new buildings and underground projects, which makes the usage of underground space indispensable. In this paper, a numerical modeling is performed using the finite element method to study the deep excavation-diaphragm wall soil-structure interaction in the case of nonlinear soil behavior. The study is focused on a comparison of the results obtained using different support systems. Furthermore, a parametric study is performed according to the remoteness of the structure.

Keywords: deep excavation, ground anchors, interaction soil-structure, struts

Procedia PDF Downloads 414
1743 Performance Analysis of Carbon Nanotube for VLSI Interconnects and Their Comparison with Copper Interconnects

Authors: Gagnesh Kumar, Prashant Gupta

Abstract:

This paper investigates the performance of the bundle of single wall carbon nanotubes (SWCNT) for low-power and high-speed interconnects for future VLSI applications. The power dissipation, delay and power delay product (PDP) of SWCNT bundle interconnects are examined and compared with that of the Cu interconnects at 22 nm technology node for both intermediate and global interconnects. The results show that SWCNT bundle consume less power and also faster than Cu for intermediate and global interconnects. It is concluded that the metallic SWCNT has been regarded as a viable candidate for intermediate and global interconnects in future technologies.

Keywords: carbon nanotube, SWCNT, low power, delay, power delay product, global and intermediate interconnects

Procedia PDF Downloads 320
1742 The Influence of the Concentration and Temperature on the Rheological Behavior of Carbonyl-Methylcellulose

Authors: Mohamed Rabhi, Kouider Halim Benrahou

Abstract:

The rheological properties of the carbonyl-methylcellulose (CMC), of different concentrations (25000, 50000, 60000, 80000 and 100000 ppm) and different temperatures were studied. We found that the rheological behavior of all CMC solutions presents a pseudo-plastic behavior, it follows the model of Ostwald-de Waele. The objective of this work is the modeling of flow by the CMC Cross model. The Cross model gives us the variation of the viscosity according to the shear rate. This model allowed us to adjust more clearly the rheological characteristics of CMC solutions. A comparison between the Cross model and the model of Ostwald was made. Cross the model fitting parameters were determined by a numerical simulation to make an approach between the experimental curve and those given by the two models. Our study has shown that the model of Cross, describes well the flow of "CMC" for low concentrations.

Keywords: CMC, rheological modeling, Ostwald model, cross model, viscosity

Procedia PDF Downloads 405
1741 Energy Saving of the Paint with Mineral Insulators: Simulation and Study on Different Climates

Authors: A. A. Azemati, H. Hosseini, B. Shirkavand Hadavand

Abstract:

By using an adequate thermal barrier coating in buildings the energy saving will be happened. In this study, a range of wall paints with different absorption coefficient in different climates has been investigated. In order to study these effects, heating and cooling loads of a common building with different ordinary paints and paint with mineral coating have been calculated. The effect of building paint in different climatic condition was studied and comparison was done between ordinary paints and paint with mineral insulators in temperate climate to obtain optimized energy consumption. The results have been shown that coatings with inorganic micro particles as insulation reduce the energy consumption of buildings around 14%.

Keywords: climate, energy consumption, inorganic, mineral coating

Procedia PDF Downloads 268
1740 Reliability Analysis of Partial Safety Factor Design Method for Slopes in Granular Soils

Authors: K. E. Daryani, H. Mohamad

Abstract:

Uncertainties in the geo-structure analysis and design have a significant impact on the safety of slopes. Traditionally, uncertainties in the geotechnical design are addressed by incorporating a conservative factor of safety in the analytical model. In this paper, a risk-based approach is adopted to assess the influence of the geotechnical variable uncertainties on the stability of infinite slopes in cohesionless soils using the “partial factor of safety on shear strength” approach as stated in Eurocode 7. Analyses conducted using Monte Carlo simulation show that the same partial factor can have very different levels of risk depending on the degree of uncertainty of the mean values of the soil friction angle and void ratio.

Keywords: Safety, Probability of Failure, Reliability, Infinite Slopes, Sand.

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1739 Buckling Behavior of FGM Plates Using a Simplified Shear Deformation Theory

Authors: Mokhtar Bouazza

Abstract:

In this paper, the simplified theory will be used to predict the thermoelastic buckling behavior of rectangular functionally graded plates. The material properties of the functionally graded plates are assumed to vary continuously through the thickness, according to a simple power law distribution of the volume fraction of the constituents. The simplified theory is used to obtain the buckling of the plate under different types of thermal loads. The thermal loads are assumed to be uniform, linear, and non-linear distribution through the thickness. Additional numerical results are presented for FGM plates that show the effects of various parameters on thermal buckling response.

Keywords: buckling, functionally graded, plate, simplified higher-order deformation theory, thermal loading

Procedia PDF Downloads 383
1738 Forced Heat Transfer Convection in a Porous Channel with an Oriented Confined Jet

Authors: Azzedine Abdedou, Khedidja Bouhadef

Abstract:

The present study is an analysis of the forced convection heat transfer in porous channel with an oriented jet at the inlet with uniform velocity and temperature distributions. The upper wall is insulated when the bottom one is kept at constant temperature higher than that of the fluid at the entrance. The dynamic field is analysed by the Brinkman-Forchheimer extended Darcy model and the thermal field is traduced by the energy one equation model. The numerical solution of the governing equations is obtained by using the finite volume method. The results mainly concern the effect of Reynolds number, jet angle and thermal conductivity ratio on the flow structure and local and average Nusselt numbers evolutions.

Keywords: forced convection, porous media, oriented confined jet, fluid mechanics

Procedia PDF Downloads 383
1737 Wind Fragility of Window Glass in 10-Story Apartment with Two Different Window Models

Authors: Viriyavudh Sim, WooYoung Jung

Abstract:

Damage due to high wind is not limited to load resistance components such as beam and column. The majority of damage is due to breach in the building envelope such as broken roof, window, and door. In this paper, wind fragility of window glass in residential apartment was determined to compare the difference between two window configuration models. Monte Carlo Simulation method had been used to derive damage data and analytical fragilities were constructed. Fragility of window system showed that window located in leeward wall had higher probability of failure, especially those close to the edge of structure. Between the two window models, Model 2 had higher probability of failure, this was due to the number of panel in this configuration.

Keywords: wind fragility, glass window, high rise building, wind disaster

Procedia PDF Downloads 257
1736 Road Vehicle Recognition Using Magnetic Sensing Feature Extraction and Classification

Authors: Xiao Chen, Xiaoying Kong, Min Xu

Abstract:

This paper presents a road vehicle detection approach for the intelligent transportation system. This approach mainly uses low-cost magnetic sensor and associated data collection system to collect magnetic signals. This system can measure the magnetic field changing, and it also can detect and count vehicles. We extend Mel Frequency Cepstral Coefficients to analyze vehicle magnetic signals. Vehicle type features are extracted using representation of cepstrum, frame energy, and gap cepstrum of magnetic signals. We design a 2-dimensional map algorithm using Vector Quantization to classify vehicle magnetic features to four typical types of vehicles in Australian suburbs: sedan, VAN, truck, and bus. Experiments results show that our approach achieves a high level of accuracy for vehicle detection and classification.

Keywords: vehicle classification, signal processing, road traffic model, magnetic sensing

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1735 Machining Stability of a Milling Machine with Different Preloaded Spindle

Authors: Jui-Pin Hung, Qiao-Wen Chang, Kung-Da Wu, Yong-Run Chen

Abstract:

This study was aimed to investigate the machining stability of a spindle tool with different preloaded amount. To this end, the vibration tests were conducted on the spindle unit with different preload to assess the dynamic characteristics and machining stability of the spindle unit. Current results demonstrate that the tool tip frequency response characteristics and the machining stabilities in X and Y direction are affected to change for spindle with different preload. As can be found from the results, a high preloaded spindle tool shows higher limited cutting depth at mid position, while a spindle with low preload shows a higher limited depth. This implies that the machining stability of spindle tool system is affected to vary by the machine frame structure. Besides, such an effect is quite different and varied with the preload of the spindle.

Keywords: bearing preload, dynamic compliance, machining stability, spindle

Procedia PDF Downloads 386
1734 The Importance of Fungi and Plants for a More Sustainable on Our Planet Earth

Authors: Njabe Christelle

Abstract:

Fungal products are essential building blocks for change towards a more sustainable future for our planet. In nature, fungi are special in breaking down plant material by means of a rich spectrum of plant cell wall degrading enzymes. Enzymes serve as catalysts in organic synthesis. Imagine the immense benefits that the known 250000 plant genes might provide in the future through scientific investigation. Plants are the primary basis for human sustenance, used directly for food, clothing, and shelter or indirectly in processed form and through animal feeding. Fungi are the only organisms known to extensively degrade lignin, a major component of wood. Although humans cannot digest cellulose and lignin, many fungi, through their assimilation of these substances, produce food in the form of edible mushrooms.

Keywords: plants, fungi, sustainable use, planet earth

Procedia PDF Downloads 81
1733 Systemic Approach to Risk Measurement of Drainage Systems in Urban Areas

Authors: Jadwiga Królikowska, Andrzej Królikowski, Jarosław Bajer

Abstract:

The work delineates the threats of maladjustment of the capacity of rain canals, designed and built in the early 20th century, in connection to heavy rainfall, especially in summer. This is the cause of the so called 'urban floods.' It directly relates to fierce raise of paving in the cities. Resolving this problem requires a change in philosophy of draining the rainfall by wider use of retention, infiltration and usage of rainwater. In systemic approach to managing the safety of urban drainage systems the risk, which is directly connected to safety failures, has been accepted as a measure. The risk level defines the probability of occurrence of losses greater than the ones forecast for a given time frame. The procedure of risk modelling, enabling its numeric analysis by using appropriate weights, is a significant issue in this paper.

Keywords: risk management, drainage system, urban areas, urban floods

Procedia PDF Downloads 361
1732 Labour-saving Construction Using Buildability Framework through Strengthening Designers in Delivering More Buildable Designs

Authors: Muhammad Lawal A., Abdullateef Abdulkarim Jimoh

Abstract:

This study is to appraise the labour-saving construction methods achievable using a buildability framework through an improved design system. Adoption of labour-efficient technology and construction techniques will be necessary to supplement good buildable designs. Increased usage of prefabricated, modular, and standardized construction components, simplicity in the design, and the number of integrated elements all work to advance buildable design. The objectives of the study include `determining a more efficient buildability framework for designers to achieve labour-saving construction’. 20 completed building projects in Birnin Kebbi, Nigeria, is used as a case study to buttress the proposition that `a more buildable design using buildability frame result in labour-saving in construction adopting a Singapore study approach.

Keywords: buildability framework, buildable designs, construction, labour-saving construction

Procedia PDF Downloads 99
1731 Development of Palm Kernel Shell Lightweight Masonry Mortar

Authors: Kazeem K. Adewole

Abstract:

There need to construct building walls with lightweight masonry bricks/blocks and mortar to reduce the weight and cost of cooling/heating of buildings in hot/cold climates is growing partly due to legislations on energy use and global warming. In this paper, the development of Palm Kernel Shell masonry mortar (PKSMM) prepared with Portland cement and crushed PKS fine aggregate (an agricultural waste) is demonstrated. We show that PKSMM can be used as a lightweight mortar for the construction of lightweight masonry walls with good thermal insulation efficiency than the natural river sand commonly used for masonry mortar production.

Keywords: building walls, fine aggregate, lightweight masonry mortar, palm kernel shell, wall thermal insulation efficacy

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1730 Heritage Sharing Problems in Land Registry: Case Study of Konya, Turkey

Authors: Tayfun Cay, Sabahattin Akkus

Abstract:

Due to inheritance, urban areas can not be arranged in a planned and programmed manner. As a result of this, the social fabric is disrupted and the hostility is increasing among the people. This contradicts the understanding of the social state. The Turkish Civil Code and the Urban Development Law are effective in sharing heritage in urban areas in Turkey. Within the framework of this legislation; How to make heritage sharing and services in the title deed. In this study, these laws, regulations, and statutes are examined. In the frame of this legislation, land registry problems on inheritance are examined and the province of Konya - Selçuk district, is selected as an application place to solve the problems. In this study, the problems of heritage sharing in the land registry were investigated. The evaluation of the work is done and the results are determined and possible solutions are proposed.

Keywords: land, land registry, heritage sharing, sharing problems of heritage

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1729 Exploring Artistic Creation and Autoethnography in the Spatial Context of Geography

Authors: Sinem Tas

Abstract:

This research paper attempts to study the perspective of personal experience in relation to spatial dynamics and artistic outcomes within the realm of cultural identity. This article serves as a partial analysis within a broader PhD investigation that focuses on the cultural dynamics and political structures behind cultural identity through an autoethnography of narrative while presenting its correlation with artistic creation in the context of space and people. Focusing on the artistic/creative practice project AUTRUI, the primary goal is to analyse and understand the influence of personal experiences and culturally constructed identity as an artist in resulting in the compositional modality of the last image considering self-reflective experience. Referencing the works of Joyce Davidson and Christine Milligan - the scholars who emphasise the importance of emotion and spatial experience in geographical studies contribute to this work as they highlight the significance of emotion across various spatial scales in their work Embodying Emotion Sensing Space: Introducing Emotional Geographies (2004). Their perspective suggests that understanding emotions within different spatial contexts is crucial for comprehending human experiences and interactions with space. Incorporating the insights of scholars like Yi-Fu Tuan, particularly his seminal work Space and Place: The Perspective of Experience (1979), is important for creating an in-depth frame of geographical experience. Tuan's humanistic perspective on space and place provides a valuable theoretical framework for understanding the interplay between personal experiences and spatial contexts. A substantial contextualisation of the geopolitics of Turkey - the implications for national identity and cohesion - will be addressed by drawing an outline of the political and geographical frame as a methodological strategy to understand the dynamics behind this research. Besides the bibliographical reading, the methods used to study this relation are participatory observation, memory work along with memoir analysis, personal interviews, and discussion of photographs and news. The utilisation of the self as data requires the analysis of the written sources with personal engagement. By delving into written sources such as written communications or diaries as well as memoirs, the research gains a firsthand perspective, enriching the analytical depth of the study. Furthermore, the examination of photography and news articles serves as a valuable means of contextualising experiences from a journalist's background within specific geographical settings. The inclusion of interviews with close family members access provides firsthand perspectives and intimate insights rooted in shared experiences within similar geographical contexts, offering complementary insights and diversified viewpoints, enhancing the comprehensiveness of the investigation.

Keywords: art, autoethnography, place and space, Turkey

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1728 Single Carrier Frequency Domain Equalization Design to Cope with Narrow Band Jammer

Authors: So-Young Ju, Sung-Mi Jo, Eui-Rim Jeong

Abstract:

In this paper, based on the conventional single carrier frequency domain equalization (SC-FDE) structure, we propose a new SC-FDE structure to cope with narrowband jammer. In the conventional SC-FDE structure, channel estimation is performed in the time domain. When a narrowband jammer exists, time-domain channel estimation is very difficult due to high power jamming interference, which degrades receiver performance. To relieve from this problem, a new SC-FDE frame is proposed to enable channel estimation under narrow band jamming environments. In this paper, we proposed a modified SC-FDE structure that can perform channel estimation in the frequency domain and verified the performance via computer simulation.

Keywords: channel estimation, jammer, pilot, SC-FDE

Procedia PDF Downloads 475
1727 The Systemic Approach to Risk Measurement of Drainage Systems in Urban Areas

Authors: Jadwiga Królikowska, Andrzej Królikowski, Jarosław Bajer

Abstract:

The work delineates the threats of maladjustment of the capacity of rain canals, designed and built in the early 20th century, in connection to heavy rainfall, especially in summer. This is the cause of the so called 'urban floods.' It directly relates to fierce raise of paving in the cities. Resolving this problem requires a change in philosophy of draining the rainfall by wider use of retention, infiltration and usage of rainwater. In systemic approach to managing the safety of urban drainage systems the risk, which is directly connected to safety failures, has been accepted as a measure. The risk level defines the probability of occurrence of losses grater than the ones forecast for a given time frame. The procedure of risk modelling, enabling its numeric analysis by using appropriate weights, is a significant issue in this paper.

Keywords: drainage system, urban areas, risk measurement, systemic approach

Procedia PDF Downloads 294
1726 Mechanical Characteristics on Fatigue Crack Propagation in Aluminum Plate

Authors: A. Chellil, A. Nour, S. Lecheb , H. Mechakra, L. Addar, H. Kebir

Abstract:

This paper present a mechanical characteristics on fatigue crack propagation in Aluminium Plate based on strain and stress distribution using the abaqus software. The changes in shear strain and stress distribution during the fatigue cycle with crack growth is identified. In progressive crack in the strain distribution and the stress is increase in the critical zone. Numerical Modal analysis of the model developed, prove that the Eigen frequencies of aluminium plate were decreased after cracking, and this reduce is nonlinear. These results can provide a reference for analysts and designers of aluminium alloys in aeronautical systems. Therefore, the modal analysis is an important factor for monitoring the aeronautic structures.

Keywords: aluminum alloys, plate, crack, failure

Procedia PDF Downloads 428
1725 Numerical Investigation of Thermal Energy Storage System with Phase Change Materials

Authors: Mrityunjay Kumar Sinha, Mayank Srivastava

Abstract:

The position of interface and temperature variation of phase change thermal energy storage system under constant heat injection and radiative heat injection is analysed during charging/discharging process by Heat balance integral method. The charging/discharging process is solely governed by conduction. Phase change material is kept inside a rectangular cavity. Time-dependent fixed temperature and radiative boundary condition applied on one wall, all other walls are thermally insulated. Interface location and temperature variation are analysed by using MATLAB.

Keywords: conduction, melting/solidification, phase change materials, Stefan’s number

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1724 Numerical Study of Natural Convection of a Localized Heat Source at the up of a Nanofluid-Filled Enclosure

Authors: Marziyeh Heydari, Hossein Shokouhmand

Abstract:

This article presents a numerical study of natural convection of a heat source embedded on the up wall of an enclosure filled with nanofluid. The bottom and vertical walls of the enclosure are maintained at a relatively low temperature. The type of nanofluid and solid volume fraction of nanoparticle on the heat transfer performance is studied. The results indicated that adding nanoparticle into pure paraffin improves heat transfer. The results are presented over a wide range of Rayleigh numbers(Ra=〖10〗^3 〖-10〗^5), the volume fraction of nanoparticles (0≤ɸ≤0.4%). For an enclosure, the Nusselt number of a cu-paraffin nanofluid was reduced by increasing the volume fraction of nanoparticles above 0.2%.

Keywords: nanofluid, heat transfer, heat source, enclosure

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1723 Dynamical and Thermal Study of Twin Impinging Jets a Vertical Plate with Various Jet Velocities and Impinging Distance

Authors: Louaifi Hamaili Samira, Mataoui Amina, Cheraitia Tadjeddine

Abstract:

This investigation proposes a numerical analysis of two turbulent parallel jets impinging a heated plate. The heat transfer enhancement is carried out according of the main parameters of the jet-wall interaction. The numerical solution of the stationary equations (RANS) is performed by the finite volume method using the k - ε model. A parametric study is performed to evaluate simultaneously the effect of nozzle-plate distance and velocity ratios in the range 0≤λ≤1. It is found that good local cooling is obtained for λ= 0.25 when the impinging distance is between 4w and 8w than for velocity ratios λ=1 and λ= 0.75. On the other hand, for impinging distances exceeding 8w, the velocity ratio λ =0.75 is more appropriate for good local cooling of the plate.

Keywords: two unequal jets, turbulence, mixing, heat transfer, CFD

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1722 Heat and Mass Transfer Study of Supercooled Large Droplet Icing

Authors: Du Yanxia, Stephan E. Bansmer, Gui Yewei, Xiao Guangming, Yang Xiaofeng

Abstract:

The heat and mass transfer characteristics of icing coupled with film flow is studied and the coupled model of the thermal behavior with the flow simulation by single-step method is developed. The behavior of ice and water was analyzed. The results show that under supercooled large droplet (SLD) icing conditions, the film flow is an important phonomena in icing accretion process. The pressure gradient, gravity and shear stress are the main factors affecting the film flow on icing surface, which has important influence on the shape and rate of icing. To predict SLD ice accretion accurately, the heat and mass transfer of ice and film flow should be taken into account.

Keywords: SLD, aircraft, icing, heat and mass transfer

Procedia PDF Downloads 634
1721 Behaviour of Reinforced Concrete Infilled Frames under Seismic Loads

Authors: W. Badla

Abstract:

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 546
1720 Oscillatory Electroosmotic Flow in a Microchannel with Slippage at the Walls and Asymmetric Wall Zeta Potentials

Authors: Oscar Bautista, Jose Arcos

Abstract:

In this work, we conduct a theoretical analysis of an oscillatory electroosmotic flow in a parallel-plate microchannel taking into account slippage at the microchannel walls. The governing equations given by the Poisson-Boltzmann (with the Debye-Huckel approximation) and momentum equations are nondimensionalized from which four dimensionless parameters appear; a Reynolds angular number, the ratio between the zeta potentials of the microchannel walls, the electrokinetic parameter and the dimensionless slip length which measures the competition between the Navier slip length and the half height microchannel. The principal results indicate that the slippage has a strong influence on the magnitude of the oscillatory electroosmotic flow increasing the velocity magnitude up to 50% for the numerical values used in this work.

Keywords: electroosmotic flows, oscillatory flow, slippage, microchannel

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1719 Theoretical Prediction of the Structural, Elastic, Electronic, Optical, and Thermal Properties of Cubic Perovskites CsXF3 (X = Ca, Sr, and Hg) under Pressure Effect

Authors: M. A. Ghebouli, A. Bouhemadou, H. Choutri, L. Louaila

Abstract:

Some physical properties of the cubic perovskites CsXF3 (X = Sr, Ca, and Hg) have been investigated using pseudopotential plane–wave (PP-PW) method based on the density functional theory (DFT). The calculated lattice constants within GGA (PBE) and LDA (CA-PZ) agree reasonably with the available experiment data. The elastic constants and their pressure derivatives are predicted using the static finite strain technique. We derived the bulk and shear moduli, Young’s modulus, Poisson’s ratio and Lamé’s constants for ideal polycrystalline aggregates. The analysis of B/G ratio indicates that CsXF3 (X = Ca, Sr, and Hg) are ductile materials. The thermal effect on the volume, bulk modulus, heat capacities CV, CP, and Debye temperature was predicted.

Keywords: perovskite, PP-PW method, elastic constants, electronic band structure

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1718 Learning And Teaching Conditions For Students With Special Needs: Asset-Oriented Perspectives And Approaches

Authors: Dr. Luigi Iannacci

Abstract:

This research critically explores the current educational landscape with respect to special education and dominant deficit/medical model discourses that continue to forward unresponsive problematic approaches to teaching students with disabilities. Asset-oriented perspectives and social/critical models of disability are defined and explicated in order to offer alternatives to these dominant discourses. To that end, a framework that draws on Brian Camborne’s conditions of learning and applications of his work in relation to instruction conceptualize learning conditions and their significance to students with special needs. Methodologically, the research is designed as Critical Narrative Inquiry (CNI). Critical incidents, interviews, documents, artefacts etc. are drawn on and narratively constructed to explore how disability is presently configured in language, discourses, pedagogies and interactions with students deemed disabled. This data was collected using ethnographic methods and as such, through participant-observer field work that occurred directly in classrooms. This narrative approach aims to make sense of complex classroom interactions and ways of reconceptualizing approaches to students with special needs. CNI is situated in the critical paradigm and primarily concerned with culture, language and participation as issues of power in need of critique with the intent of change in the direction of social justice. Research findings highlight the ways in which Cambourne’s learning conditions, such as demonstration, approximation, engagement, responsibility, immersion, expectation, employment (transfer, use), provide a clear understanding of what is central to and constitutes a responsive and inclusive this instructional frame. Examples of what each of these conditions look like in practice are therefore offered in order to concretely demonstrate the ways in which various pedagogical choices and questions can enable classroom spaces to be responsive to the assets and challenges students with special needs have and experience. These particular approaches are also illustrated through an exploration of multiliteracies theory and pedagogy and what this research and approach allows educators to draw on, facilitate and foster in terms of the ways in which students with special needs can make sense of and demonstrate their understanding of skills, content and knowledge. The contextual information, theory, research and instructional frame focused on throughout this inquiry ultimately demonstrate what inclusive classroom spaces and practice can look like. These perspectives and conceptualizations are in stark contrast to dominant deficit driven approaches that ensure current pedagogically impoverished teaching focused on narrow, limited and limiting understandings of special needs learners and their ways of knowing and acquiring/demonstrating knowledge.

Keywords: asset-oriented approach, social/critical model of disability, conditions for learning and teaching, students with special needs

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1717 Raman Spectroscopy of Carbon Nanostructures in Strong Magnetic Field

Authors: M. Kalbac, T. Verhagen, K. Drogowska, J. Vejpravova

Abstract:

One- and two-dimensional carbon nano structures with sp2 hybridization of carbon atoms (single walled carbon nano tubes and graphene) are promising materials in future electronic and spintronics devices due to specific character of their electronic structure. In this paper, we present a comparative study of graphene and single-wall carbon nano tubes by Raman spectro-microscopy in strong magnetic field. This unique method allows to study changes in electronic band structure of the two types of carbon nano structures induced by a strong magnetic field.

Keywords: carbon nano structures, magnetic field, raman spectroscopy, spectro-microscopy

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