Search results for: concrete large panel wall

Authors: Qian You, Ibrahim Hassan, Lyes Kadem

Abstract:

An experiment is conducted to fundamentally investigate flow oscillation characteristics in different sizes of single microtubes in vertical upward flow direction. Three microtubes have 0.889 mm, 0.533 mm, and 0.305 mm hydraulic diameters with 100 mm identical heated length. The mass flux of the working fluid FC-72 varies from 700 kg/m2•s to 1400 kg/m2•s, and the heat flux is uniformly applied on the tube surface up to 9.4 W/cm2. The subcooled inlet temperature is maintained around 24°C during the experiment. The effect of hydraulic diameter and mass flux are studied. The results showed that they have interactions on the flow oscillations occurrence and behaviors. The onset of flow instability (OFI), which is a threshold of unstable flow, usually appears in large microtube with diversified and sustained flow oscillations, while the transient point, which is the point when the flow turns from one stable state to another suddenly, is more observed in small microtube without characterized flow oscillations due to the bubble confinement. The OFI/transient point occurs early as hydraulic diameter reduces at a given mass flux. The increased mass flux can delay the OFI/transient point occurrence in large hydraulic diameter, but no significant effect in small size. Although the only transient point is observed in the smallest tube, it appears at small heat flux and is not sensitive to mass flux; hence, the smallest microtube is not recommended since increasing heat flux may cause local dryout.

Keywords: flow boiling instability, hydraulic diameter effect, a single microtube, vertical upward flow

Procedia PDF Downloads 605

Authors: Luis Felipe Brito-Gaona, Emma M. Iglesias

Abstract:

There is a growing literature that studies the main determinants and drivers of inequality and economic growth in several countries, using panel data and different estimation methods (fixed effects, Generalized Methods of Moments (GMM) and Two Stages Least Squares (TSLS)). Recently, it was studied the evolution of these variables in the period 1980-2009 in the 18 countries of Latin-America and it was found that one of the main variables that explained their evolution was Foreign Direct Investment (FDI). We extend this study to the year 2015 in the same 18 countries in Latin-America, and we find that FDI does not have a significant role anymore, while we find a significant negative and positive effect of schooling levels on inequality and economic growth respectively. We also find that the point estimates associated with human capital are the largest ones of the variables included in the analysis, and this means that an increase in human capital (measured by schooling levels of secondary education) is the main determinant that can help to reduce inequality and to increase economic growth in Latin-America. Therefore, we advise that economic policies in Latin-America should be directed towards increasing the level of education. We use the methodologies of estimating by fixed effects, GMM and TSLS to check the robustness of our results. Our conclusion is the same regardless of the estimation method we choose. We also find that the international recession in the Latin-American countries in 2008 reduced significantly their economic growth.

Keywords: economic growth, human capital, inequality, Latin-America

Procedia PDF Downloads 231

Authors: F. Ece Cetin, H. Nezih Ozdemir, Emre Kumral

Abstract:

Ischemic stroke of the precuneal cortex (PC) alone is extremely rare. This study aims to evaluate the clinical, neurocognitive, and behavioural characteristics of isolated PC infarcts. We assessed neuropsychological and behavioral findings in 12 patients with isolated PC infarct among 3800 patients with ischemic stroke. To determine the most frequently affected brain locus in patients, we first overlapped the ischemic area of patients with specific cognitive disorders and patients without specific cognitive disorders. Secondly, we compared both overlap maps using the 'subtraction plot' function of MRIcroGL. Patients showed various types of cognitive disorders. All patients experienced more than one category of cognitive disorder, except for two patients with only one cognitive disorder. Lesion topographical analysis showed that damage within the anterior precuneal region might lead to consciousness disorders (25%), self-processing impairment (42%), visuospatial disorders (58%), and lesions in the posterior precuneal region caused episodic and semantic memory impairment (33%). The whole precuneus is involved in at least one body awareness disorder. The cause of the stroke was cardioembolism in 5 patients (42%), large artery disease in 3 (25%), and unknown in 4 (33%). This study showed a wide variety of neuropsychological and behavioural disorders in patients with precuneal infarct. Future studies are needed to achieve a proper definition of the function of the precuneus in relation to the extended cortical areas. Precuneal cortex region infarcts have been found to predict a source of embolism from the large arteries or heart.

Keywords: cognition, pericallosal artery, precuneal cortex, ischemic stroke

Procedia PDF Downloads 133

Authors: Mansour Fakhri, Monire Zokaei

Abstract:

Where there are many demolitions on conventional asphalt pavements, heavy costs are paid to repair and reconstruct the pavement roads annually. Recently some research has been done in order to increase the pavement life. Perpetual pavement is regarded as one of them which can improve the pavement life and minimize the maintenance activity and cost. In this research, ABAQUS which is a finite element software is implemented for analyzing and simulation of perpetual pavement. Viscoelastic model of material is used and loading wheel is considered to be dynamic. Effect of different parameters on pavement function has been considered. Because of high primary cost these pavements are not widely used. In this regard, life cost analysis was also carried out to compare perpetual pavement to conventional asphalt concrete pavement. It was concluded that although the initial cost of perpetual pavement is higher than that of conventional asphalt pavement, life cycle cost analysis during 50 years of service life showed that the performance of this pavement is better and the whole life cost of that is less.

Keywords: ABAQUS, lifecycle cost analysis, mechanistic empirical, perpetual pavement

Procedia PDF Downloads 387

Authors: Gaylord K. Booto, Marinelli Giuseppe, Helge Brattebø, Rolf A. Bohne

Abstract:

Emissions reduction has emerged among the principal targets in the process of planning and designing road alignments today. Intelligent road design methods that can result in optimized alignment constitute concrete and innovative responses towards better alternatives and more sustainable road infrastructures. As the largest amount of emissions of road infrastructures occur in the operation stage, it becomes very important to consider traffic weight and distribution in alignment design process. This study analyzes the effects of four traffic factors (i.e. operating speed, vehicle category, technology and fuel type) on adjusting the vertical alignment of a given road, using optimization techniques. Further, factors’ effects are assessed qualitatively and quantitatively, and the emission profiles of resulting alignment alternatives are compared.

Keywords: alignment adjustment, emissions reduction, optimization, traffic-oriented

Procedia PDF Downloads 373

Authors: Hansoo Kim, Seunghak Shin

Abstract:

The differential column shortening in tall buildings can be reduced by improving material and structural characteristics of the structural systems. This paper proposes structural methods to reduce differential column shortening in reinforced concrete tall buildings; connecting columns with rigidly jointed horizontal members, using outriggers, and placing additional reinforcement at the columns. The rigidly connected horizontal members including outriggers reduce the differential shortening between adjacent vertical members. The axial stiffness of columns with greater shortening can be effectively increased by placing additional reinforcement at the columns, thus the differential column shortening can be reduced in the design stage. The optimum distribution of additional reinforcement can be determined by applying a gradient based optimization technique.

Keywords: column shortening, long-term behavior, optimization, tall building

Procedia PDF Downloads 253

Authors: A. Bouriche, D. Merah, L.Alachaher-Bedjaoui, U. Maschke

Abstract:

Intensive research continues in the field of liquid crystals (LCs) for their potential use in modern display applications. Nematic LCs has been most commonly used due to the large birefringence and their sensitivity to even weak perturbation forces induced by electric, magnetic and optical fields. Polymer dispersed liquid crystals (PDLCs), composed of micron-sized nematic LC droplets dispersed in a polymer matrix is an important class of materials for applications in different domains of technology involving large area display devices, optical switches, phase modulators, variable attenuators, polarisers, flexible displays and smart windows. In this study the composites are prepared from mixtures of monofunctional acrylic monomers, (Butylacrylate (ABu), 2-Ethylhexylacrylate (2-EHA), 2-Hydroxyethyl methacrylate (HEMA) and hydroxybutylmethacrylate (HBMA)) and two liquid crystals: (4-cyano-4'-n-pentyl-biphenyl) (5CB) and E7 which is an eutectic mixtures of four cyanoparaphenylenes. These mixtures are prepared adding the Darocur 1173 as photoinitiateor, the 1.6-hexanediol diacrylate (HDDA) as cross-linker agent, and finally they are exposed to UV irradiation. The kinetic polymerization of monomer/LC mixture were investigated with the Fourier Transform Infra Red spectroscopy (FTIR). The electro-optical properties of the PDLC films were determined by measuring the voltage dependence on the transmitted light.

Keywords: acrylic monomers, films PDLC, liquid crystal, polymerisation

Procedia PDF Downloads 331

Authors: Tijjani Bashir Musa

Abstract:

The recent global crisis which suddenly results to Nigerian stock market crash revealed some peculiarities of Nigerian firms. Some firms in Nigeria are performing but their stock prices are not increasing while some firms are at the brink of collapse but their stock prices are increasing. Thus, this study examines the relationship between firm performance and stock price in Nigeria. The study covered the period of 2005 to 2009. This period is the period of stock boom and also marked the period of stock market crash as a result of global financial meltdown. The study is a panel study. A total of 140 firms were sampled from 216 firms listed on the Nigerian Stock Exchange (NSE). Data were collected from secondary source. These data were divided into four strata comprising the most performing stock, the least performing stock, most performing firms and the least performing firms. Each stratum contains 35 firms with characteristic of most performing stock, most performing firms, least performing stock and least performing firms. Multiple linear regression models were used to analyse the data while statistical/econometrics package of Stata 11.0 version was used to run the data. The study found that, relationship exists between selected firm performance parameters (operating efficiency, firm profit, earning per share and working capital) and stock price. As such firm performance gave sufficient information or has predictive power on stock prices movements in Nigeria for all the years under study.. The study recommends among others that Managers of firms in Nigeria should formulate policies and exert effort geared towards improving firm performance that will enhance stock prices movements.

Keywords: firm, Nigeria, performance, stock price

Procedia PDF Downloads 481

Authors: Khaleed Alsufyyan

Abstract:

This doctoral research has been successfully approved by a specialist upgrade panel, and it presents the proposition that the KSA policy for combating maritime terrorism is inadequate and current governance frameworks, including laws, are insufficiently developed to respond effectively and fairly to maritime terrorism. It will examine the legal system in the KSA in terms of effectiveness fairness, as well as investigate this proposition to determine what factors have contributed to such a deficiency. The main focus of this research will draw upon the policies, laws, and practices of the KSA, as well as UK and international laws and policies, to assess whether it is feasible to apply them in the context of the KSA. This thesis will recommend strategies regarding maritime terrorism to enrich the legal and policy frameworks and address the current and future dynamics of maritime terrorism adequately. To derive suitable improvements, UK policies, laws, and practices will be considered for policy transfer purposes. As for studies focused on the KSA, since the KSA is a Muslim state, it will be important to assess the impact of Islamic Law or Sharia Law subject to the doctrines of fairness and effectiveness to comprehend how the KSA’s legal system operates and determine the boundaries it sets for the response to maritime terrorism. This thesis will propose that more reforms are needed to effectively and fairly deal with maritime terrorism based on the prevailing understanding of Sharia law. The research will address the international perspectives on the problem of maritime terrorism and international cooperation of the KSA regarding maritime terrorism and consider the need for further developments.

Keywords: maritime terrorism, maritime security, combat maritime terrorism in the KSA, protecting maritime transport against terrorism

Procedia PDF Downloads 91

Authors: Murtaza Adil, Sen Yang, Zhou Chao, Song Xiaoping

Abstract:

The morphotropic phase boundary (MPB) recently has attracted constant interest in ferromagnetic systems for obtaining enhanced large magnetoelastic response. In the present study, structural and magnetoelastic properties of MPB involved ferromagnetic Tb_1-xGd_xFe₂ (0≤x≤1) system has been investigated. The change of easy magnetic direction from <111> to <100> with increasing x up MPB composition of x=0.9 is detected by step-scanned [440] synchrotron X-ray diffraction reflections. The Gd substitution for Tb changes the composition for the anisotropy compensation near MPB composition of x=0.9, which was confirmed by the analysis of detailed scanned XRD, magnetization curves and the calculation of the first anisotropy constant K₁. The spin configuration diagram accompanied with different crystal structures for Tb_1-xGd_xFe₂ was designed. The calculated first anisotropy constant K₁ shows a minimum value at MPB composition of x=0.9. In addition, the large ratio between magnetostriction, and the absolute values of the first anisotropy constant │λ_S∕K₁│ appears at MPB composition, which makes it a potential material for magnetostrictive application. Based on experimental results, a theoretically approach was also proposed to signify that the facilitated magnetization rotation and enhanced magnetoelastic effect near MPB composition are a consequence of the anisotropic flattening of free energy of ferromagnetic crystal. Our work specifies the universal existence of MPB in ferromagnetic materials which is important for substantial improvement of magnetic and magnetostrictive properties and may provide a new route to develop advanced functional materials.

Keywords: free energy, magnetic anisotropy, magnetostriction, morphotropic phase boundary (MPB)

Procedia PDF Downloads 280

Authors: Maheshwari Payal, Shapurkar Mayaan

Abstract:

The present research aimed at studying the awareness and attitudes of teachers towards inclusive education. The sample consisted of 60 teachers, teaching in the primary section (1st – 4th) of regular schools affiliated to the SSC board in Mumbai. The sample was selected by Multi-stage cluster sampling technique. A semi-structured self-constructed interview schedule and a self-constructed attitude scale were used to study the awareness of teachers about disability and Inclusive education, and their attitudes towards inclusive education respectively. Themes were extracted from the interview data and quantitative data was analyzed using SPSS package. Results revealed that teachers had some amount of awareness but an inadequate amount of information on disabilities and inclusive education. Disability to most (37) teachers meant “an inability to do something”. The difference between disability and handicap was stated by most as former being cognitive while handicap being physical in nature. With regard to Inclusive education, a large number (46) stated that they were unaware of the term and did not know what it meant. The majority (52) of them perceived maximum challenges for themselves in an inclusive set up, and emphasized on the role of teacher training courses in the area of providing knowledge (49) and training in teaching methodology (53). Although, 83.3% of teachers held a moderately positive attitude towards inclusive education, a large percentage (61.6%) of participants felt that being in inclusive set up would be very challenging for both children with special needs and without special needs. Though, most (49) of the teachers stated that children with special needs should be educated in a regular classroom, but they further clarified that only those should be in a regular classroom who have physical impairments of mild or moderate degree.

Keywords: attitude, awareness, inclusive education, teachers

Procedia PDF Downloads 325

Authors: Hussein Togun, Tuqa Abdulrazzaq, S. N. Kazi, A. Badarudin, M. K. A. Ariffin, M. N. M. Zubir

Abstract:

Heat transfer and laminar fluid flow over backward facing step with and without obstacle numerically studied in this paper. The finite volume method adopted to solve continuity, momentum and energy equations in two dimensions. Backward facing step without obstacle and with different dimension of obstacle were presented. The step height and expansion ratio of channel were 4.8mm and 2 respectively, the range of Reynolds number varied from 75 to 225, constant heat flux subjected on downstream of wall was 2000W/m2, and length of obstacle was 1.5, 3, and 4.5mm with width 1.5mm. The separation length noticed increase with increase Reynolds number and height of obstacle. The result shows increase of heat transfer coefficient for backward facing step with obstacle in compared to those without obstacle. The maximum enhancement of heat transfer observed at 4.5mm of height obstacle due to increase recirculation flow after the obstacle in addition that at backward. Streamline of velocity showing the increase of recirculation region with used obstacle in compared without obstacle and highest recirculation region observed at obstacle height 4.5mm. The amount of enhancement heat transfer was varied between 3-5% compared to backward without obstacle.

Keywords: separation flow, backward facing step, heat transfer, laminar flow

Procedia PDF Downloads 474

Authors: P. Panwalkar, K. Veravalli, M. Tofighi, A. Mofidi

Abstract:

Introduction: Anterior femoral perforation or distal anterior nail position is a known complication of femoral nailing specifically in pertrochantric fractures fixed with cephalomedullary nail. This has been attributed to wrong entry point for the femoral nail, nail with large radius of curvature or malreduced fracture. Left alone anterior perforation of femur or abutment of nail on anterior femur will result in pain and risk stress riser at distal femur and periprosthetic fracture. There have been multiple techniques described to avert or correct this problem ranging from using different nail, entry point change, poller screw to deflect the nail position, use of shorter nail or use of curved guidewire or change of nail to ensure a nail with large radius of curvature Methods: We present this technique which we have used in order to centralise the femoral nail either when the nail has been put anteriorly or when the guide wire has been inserted too anteriorly prior to the insertion of the nail. This technique requires the use of femoral reduction spool from the nailing set. This technique was used by eight trainees of different level of experience under supervision. Results: This technique was easily reproducible without any learning curve without a need for opening of fracture site or change in the entry point with three different femoral nailing sets in twenty-five cases. The process took less than 10 minutes even when revising a malpositioned femoral nail. Conclusion: Our technique of using femoral reduction spool is easily reproducible and repeatable technique for avoidance of non-centralised femoral nail insertion and distal anterior perforation of femoral nail.

Keywords: femoral fracture, nailing, malposition, surgery

Procedia PDF Downloads 145

Authors: Thulodin Mat Lazim, Aminuddin Saat, Ammar Fakhir Abdulwahid, Zaid Sattar Kareem

Abstract:

Film cooling is one of the cooling systems investigated for the application to gas turbine blades. Gas turbines use film cooling in addition to turbulence internal cooling to protect the blades outer surface from hot gases. The present study concentrates on the numerical investigation of film cooling performance for a row of twisted cylindrical holes in modern turbine blade. The adiabatic film effectiveness and the heat transfer coefficient are determined numerical on a flat plate downstream of a row of inclined different cross section area hole exit by using Computational Fluid Dynamics (CFD). The swirling motion of the film coolant was induced the twisted angle of film cooling holes, which inclined an angle of α toward the vertical direction and surface of blade turbine. The holes angle α of the impingement mainstream was changed from 90°, 65°, 45°, 30° and 20°. The film cooling effectiveness on surface of blade turbine wall was measured by using 3D Computational Fluid Dynamics (CFD). Results showed that the effectiveness of rectangular twisted hole has the effectiveness among other cross section area of the hole at blowing ratio (0.5, 1, 1.5 and 2).

Keywords: turbine blade cooling, film cooling, geometry shape of hole, turbulent flow

Procedia PDF Downloads 544

Authors: Assaad Ghazouani, Hedia Teraoui

Abstract:

The purpose of this article is to try to see if the FDI actually contributes to technology transfer in Tunisia or are there other sources that can guarantee this transfer? The answer to this problem was gradual as we followed an approach using economic theory, the reality of Tunisia and econometric and statistical tools. We examined the relationship between technology transfer and FDI in Tunisia over a period of 40 years from 1970 to 2010. We estimated in two stages: first, a growth equation, then we have learned from this regression residue (proxy technology), secondly, we regressed on European FDI, exports of manufactures, imports of goods from the European Union in addition to other variables to test the robustness of the results and describing the level of infrastructure in the country. It follows from our study that technology transfer does not originate primarily and exclusively in the FDI and the latter is econometrically weakly with technology transfer and spill over effect of FDI does not seem to occur according to our results. However, the relationship between technology transfer and imports is negative and significant. Although this result is cons-intuitive, is recurrent in the literature of panel data. It has also given rise to intense debate on the microeconomic modelling as well as on the empirical applications. Technology transfer through trade or foreign investment has become a catalyst for growth recognized by numerous empirical studies in particular. However, the relationship technology transfer FDI is more complex than it appears. This complexity is due, primarily, but not exclusively to the close link between FDI and the characteristics of the host country. This is essentially the host's responsibility to establish general conditions, transparent and conducive to investment, and to strengthen human and institutional capacity necessary for foreign capital flows that can have real effects on growth.

Keywords: technology transfer, foreign direct investment, economics, finance

Procedia PDF Downloads 326

Authors: N. K. Chougule, G. V. Parishwad

Abstract:

The pin fin heat sink is a novel heat transfer device to transfer large amount of heat through with very small temperature differences and it also possesses large uniform cooling characteristics. Pin fins are widely used as elements that provide increased cooling for electronic devices. Increasing demands regarding the performance of such devices can be observed due to the increasing heat production density of electronic components. For this reason, extensive work is being carried out to select and optimize pin fin elements for increased heat transfer. In this paper, the effects of design parameters and the optimum design parameters for a Pin-Fin heat sink (PFHS) under multi-jet impingement case with thermal performance characteristics have been investigated by using Taguchi methodology based on the L9 orthogonal arrays. Various design parameters, such as pin-fin array size, gap between nozzle exit to impingement target surface (Z/d) and air velocity are explored by numerical experiment. The average convective heat transfer coefficient is considered as the thermal performance characteristics. The analysis of variance (ANOVA) is applied to find the effect of each design parameter on the thermal performance characteristics. Then the results of confirmation test with the optimal level constitution of design parameters have obviously shown that this logic approach can effective in optimizing the PFHS with the thermal performance characteristics. The analysis of the Taguchi method reveals that, all the parameters mentioned above have equal contributions in the performance of heat sink efficiency. Experimental results are provided to validate the suitability of the proposed approach.

Keywords: Pin Fin Heat Sink (PFHS), Taguchi method, CFD, thermal performance

Procedia PDF Downloads 254

Authors: Sayed Mansour, Mohammad Aldoasri, Nagib Elmarzugi, Nadia A. Al-Mouallimi

Abstract:

The archaeological large stone used in construction of ancient Pharaonic tombs, temples, obelisks and other sculptures, always subject to physicomechanical deterioration and destructive forces, leading to their partial or total broken. The task of reassembling this type of artifact represent a big challenge for the conservators. Recently, the researchers are turning to new technologies to improve the properties of traditional adhesive materials and techniques used in re-assembly of broken large stone. The epoxy resins are used extensively in stone conservation and re-assembly of broken stone because of their outstanding mechanical properties. The introduction of nanoparticles to polymeric adhesives at low percentages may lead to substantial improvements of their mechanical performances in structural joints and large objects. The aim of this study is to evaluate the effectiveness of clay nanoparticles in enhancing the performances of epoxy adhesives used in re-assembly of archaeological massive stone by adding proper amounts of those nanoparticles. The nanoparticles reinforced epoxy nanocomposite was prepared by direct melt mixing with a nanoparticles content of 3% (w/v), and then mould forming in the form of rectangular samples, and used as adhesive for experimental stone samples. Scanning electron microscopy (SEM) was employed to investigate the morphology of the prepared nanocomposites, and the distribution of nanoparticles inside the composites. The stability and efficiency of the prepared epoxy-nanocomposites and stone block assemblies with new formulated adhesives were tested by aging artificially the samples under different environmental conditions. The effect of incorporating clay nanoparticles on the mechanical properties of epoxy adhesives was evaluated comparatively before and after aging by measuring the tensile, compressive, and Elongation strength tests. The morphological studies revealed that the mixture process between epoxy and nanoparticles has succeeded with a relatively homogeneous morphology and good dispersion in low nano-particles loadings in epoxy matrix was obtained. The results show that the epoxy-clay nanocomposites exhibited superior tensile, compressive, and Elongation strength. Moreover, a marked improvement of the mechanical properties of stone joints increased in all states by adding nano-clay to epoxy in comparison with pure epoxy resin.

Keywords: epoxy resins, nanocomposites, clay nanoparticles, re-assembly, archaeological massive stones, mechanical properties

Procedia PDF Downloads 116

Authors: R. Chedid, R. Ghajar

Abstract:

Lebanon electricity crisis continues to escalate. Rationing hours still apply across the country but with different rates. The capital Beirut is subjected to 3 hours cut while other cities, town and villages may endure 9 to 14 hours of power shortage. To mitigate this situation, private diesel generators distributed illegally all over the country are being used to bridge the gap in power supply. Almost each building in large cities has its own generator and individual villages may have more than one generator supplying their loads. These generators together with their private networks form incomplete and ill-designed and managed microgrids (MG) but can be further developed to become renewable energy-based MG operating in island- or grid-connected modes. This paper will analyze the potential of introducing MG to help resolve the energy crisis in Lebanon. It will investigate the usefulness of developing MG under the prevailing situation of existing private power supply service providers and in light of the developed national energy policy that supports renewable energy development. A case study on a distribution feeder in a rural area will be analyzed using HOMER software to demonstrate the usefulness of introducing photovoltaic (PV) arrays along the existing diesel generators for all the stakeholders; namely, the developers, the customers, the utility and the community at large. Policy recommendations regarding MG development in Lebanon will be presented on the basis of the accumulated experience in private generation and the privatization and public-private partnership laws.

Keywords: decentralized systems, distributed generation, microgrids, renewable energy

Procedia PDF Downloads 141

Authors: M. Pienaar, J. W. Odendaal, J. C. Smit, J. Joubert

Abstract:

Simulations are commonly used to predict the bistatic radar cross section (RCS) of military targets since characterization measurements can be expensive and time consuming. It is thus important to accurately predict the bistatic RCS of targets. Computational electromagnetic (CEM) methods can be used for bistatic RCS prediction. CEM methods are divided into full-wave and asymptotic methods. Full-wave methods are numerical approximations to the exact solution of Maxwell’s equations. These methods are very accurate but are computationally very intensive and time consuming. Asymptotic techniques make simplifying assumptions in solving Maxwell's equations and are thus less accurate but require less computational resources and time. Asymptotic techniques can thus be very valuable for the prediction of bistatic RCS of electrically large targets, due to the decreased computational requirements. This study extends previous work by validating the accuracy of asymptotic techniques to predict bistatic RCS through comparison with full-wave simulations as well as measurements. Validation is done with canonical structures as well as complex realistic aircraft models instead of only looking at a complex slicy structure. The slicy structure is a combination of canonical structures, including cylinders, corner reflectors and cubes. Validation is done over large bistatic angles and at different polarizations. Bistatic RCS measurements were conducted in a compact range, at the University of Pretoria, South Africa. The measurements were performed at different polarizations from 2 GHz to 6 GHz. Fixed bistatic angles of β = 30.8°, 45° and 90° were used. The measurements were calibrated with an active calibration target. The EM simulation tool FEKO was used to generate simulated results. The full-wave multi-level fast multipole method (MLFMM) simulated results together with the measured data were used as reference for validation. The accuracy of physical optics (PO) and geometrical optics (GO) was investigated. Differences relating to amplitude, lobing structure and null positions were observed between the asymptotic, full-wave and measured data. PO and GO were more accurate at angles close to the specular scattering directions and the accuracy seemed to decrease as the bistatic angle increased. At large bistatic angles PO did not perform well due to the shadow regions not being treated appropriately. PO also did not perform well for canonical structures where multi-bounce was the main scattering mechanism. PO and GO do not account for diffraction but these inaccuracies tended to decrease as the electrical size of objects increased. It was evident that both asymptotic techniques do not properly account for bistatic structural shadowing. Specular scattering was calculated accurately even if targets did not meet the electrically large criteria. It was evident that the bistatic RCS prediction performance of PO and GO depends on incident angle, frequency, target shape and observation angle. The improved computational efficiency of the asymptotic solvers yields a major advantage over full-wave solvers and measurements; however, there is still much room for improvement of the accuracy of these asymptotic techniques.

Keywords: asymptotic techniques, bistatic RCS, geometrical optics, physical optics

Procedia PDF Downloads 261

Authors: Essam Mansour

Abstract:

The key purpose of this study is to provide first-hand information about beggars in Egypt, especially from the perspective of their information seeking behaviour including their information needs. The researcher tries to investigate the information-seeking behaviour of Egyptian beggars with regard to their thoughts, perceptions, motivations, attitudes, habits, preferences as well as challenges that may impede their use of information. The research methods used were an adapted form of snowball sampling of a heterogeneous demographic group of participants in the beggary activity in Egypt. This sampling was used to select focus groups to explore a range of relevant issues. Data on the demographic characteristics of the Egyptian beggars showed that they tend to be men, mostly with no formal education, with an average age around 30s, labeled as low-income persons, mostly single and mostly Muslims. A large number of Egyptian beggars were seeking for information to meet their basic needs as well as their daily needs, although some of them were not able to identify their information needs clearly. The information-seeking behaviour profile of a very large number of Egyptian beggars indicated a preference for informal sources of information over formal ones to solve different problems and meet the challenges they face during their beggary activity depending on assistive devices, such as mobile phones. The high degree of illiteracy and the lack of awareness about the basic rights of information as well as information needs were the most important problems Egyptian beggars face during accessing information. The study recommended further research to be conducted about the role of the library in the education of beggars. It also recommended that beggars’ awareness about their information rights should be promoted through educational programs that help them value the role of information in their life.

Keywords: user studies, information-seeking behaviour, information needs, information sources, beggars, Egypt

Procedia PDF Downloads 322

Authors: Mamta Rajbhar, Sanjay K. Mohanty

Abstract:

India's progress in achieving replacement level of fertility is largely contingent on fertility reduction in the state of Uttar Pradesh as it accounts 17% of India's population with a low level of development. Though the TFR in the state has declined from 5.1 in 1991 to 3.4 by 2011, it conceals large differences in fertility level across districts. Using data from multiple sources this paper tests the hypothesis that the improvement in human development significantly reduces the fertility levels in districts of Uttar Pradesh. The unit of analyses is district, and fertility estimates are derived using the reverse survival method(RSM) while human development indices(HDI) are are estimated using uniform methodology adopted by UNDP for three period. The correlation and linear regression models are used to examine the relationship of fertility change and human development indices across districts. Result show the large variation and significant change in fertility level among the districts of Uttar Pradesh. During 1991-2011, eight districts had experienced a decline of TFR by 10-20%, 30 districts by 20-30% and 32 districts had experienced decline of more than 30%. On human development aspect, 17 districts recorded increase of more than 0.170 in HDI, 18 districts in the range of 0.150-0.170, 29 districts between 0.125-0.150 and six districts in the range of 0.1-0.125 during 1991-2011. Study shows significant negative relationship between HDI and TFR. HDI alone explains 70% variation in TFR. Also, the regression coefficient of TFR and HDI has become stronger over time; from -0.524 in 1991, -0.7477 by 2001 and -0.7181 by 2010. The regression analyses indicate that 0.1 point increase in HDI value will lead to 0.78 point decline in TFR. The HDI alone explains 70% variation in TFR. Improving the HDI will certainly reduce the fertility level in the districts.

Keywords: Fertility, HDI, Uttar Pradesh

Procedia PDF Downloads 253

Authors: Pouya Kaafi, Gholamreza Ghodrati Amiri

Abstract:

Abnormal loads due to natural events, implementation errors and some other issues can lead to occurrence of progressive collapse in structures. Most of the past researches consist of 2- Dimensional (2D) models of steel frames without consideration of the floor system effects, which reduces the accuracy of the modeling. While employing a 3-Dimensional (3D) model and modeling the concrete slab system for the floors have a crucial role in the progressive collapse evaluation. In this research, a 3D finite element model of a 5-story steel building is modeled by the ABAQUS software once with modeling the slabs, and the next time without considering them. Then, the progressive collapse potential is evaluated. The results of the analyses indicate that the lack of the consideration of the slabs during the analyses, can lead to inaccuracy in assessing the progressive failure potential of the structure.

Keywords: abnormal loads, composite floor system, intermediate steel moment resisting frame system, progressive collapse

Procedia PDF Downloads 459

Authors: Anil Saini, Jatinder Kumar Ratan

Abstract:

Now a day, the key issue for the scientific community is to devise the innovative technologies for sustainable control of urban pollution. In urban cities, a large surface area of the masonry structures, buildings, and pavements is exposed to the open environment, which may be utilized for the control of air pollution, if it is built from the photocatalytically active cement-based constructional materials such as concrete, mortars, paints, and blocks, etc. The photocatalytically active cement is formulated by incorporating a photocatalyst in the cement matrix, and such cement is generally known as self-cleaning cement In the literature, self-cleaning cement has been synthesized by incorporating nanosized-TiO₂ (n-TiO₂) as a photocatalyst in the formulation of the cement. However, the utilization of n-TiO₂ for the formulation of self-cleaning cement has the drawbacks of nano-toxicity, higher cost, and agglomeration as far as the commercial production and applications are concerned. The use of microsized-TiO₂ (m-TiO₂) in place of n-TiO₂ for the commercial manufacture of self-cleaning cement could avoid the above-mentioned problems. However, m-TiO₂ is less photocatalytically active as compared to n- TiO₂ due to smaller surface area, higher band gap, and increased recombination rate. As such, the use of m-TiO₂ in the formulation of self-cleaning cement may lead to a reduction in photocatalytic activity, thus, reducing the self-cleaning, depolluting, and antimicrobial abilities of the resultant cement material. So improvement in the photoactivity of m-TiO₂ based self-cleaning cement is the key issue for its practical applications in the present scenario. The current work proposes the use of surface-fluorinated m-TiO₂ for the formulation of self-cleaning cement to enhance its photocatalytic activity. The calcined dolomite, a constructional material, has also been utilized as co-adsorbent along with the surface-fluorinated m-TiO₂ in the formulation of self-cleaning cement to enhance the photocatalytic performance. The surface-fluorinated m-TiO₂, calcined dolomite, and the formulated self-cleaning cement were characterized using diffuse reflectance spectroscopy (DRS), X-ray diffraction analysis (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), BET (Brunauer–Emmett–Teller) surface area, and energy dispersive X-ray fluorescence spectrometry (EDXRF). The self-cleaning property of the as-prepared self-cleaning cement was evaluated using the methylene blue (MB) test. The depolluting ability of the formulated self-cleaning cement was assessed through a continuous NOX removal test. The antimicrobial activity of the self-cleaning cement was appraised using the method of the zone of inhibition. The as-prepared self-cleaning cement obtained by uniform mixing of 87% clinker, 10% calcined dolomite, and 3% surface-fluorinated m-TiO₂ showed a remarkable self-cleaning property by providing 53.9% degradation of the coated MB dye. The self-cleaning cement also depicted a noteworthy depolluting ability by removing 5.5% of NOx from the air. The inactivation of B. subtiltis bacteria in the presence of light confirmed the significant antimicrobial property of the formulated self-cleaning cement. The self-cleaning, depolluting, and antimicrobial results are attributed to the synergetic effect of surface-fluorinated m-TiO₂ and calcined dolomite in the cement matrix. The present study opens an idea and route for further research for acile and economical formulation of self-cleaning cement.

Keywords: microsized-titanium dioxide (m-TiO₂), self-cleaning cement, photocatalysis, surface-fluorination

Procedia PDF Downloads 176

Authors: Jaden Lu, Olivia Lu

Abstract:

Despite the remarkable advancement of solar cell technology, the challenge of optimizing total solar energy harvest efficiency persists, primarily due to significant heat loss. This excess heat not only diminishes solar panel output efficiency but also curtails its operational lifespan. A promising approach to address this issue is the conversion of surplus heat into electricity. In recent years, there is growing interest in the use of thermoelectric generators (TEG) as a potential solution. The integration of efficient TEG devices holds the promise of augmenting overall energy harvest efficiency while prolonging the longevity of solar panels. While certain research groups have proposed the integration of solar cells and TEG devices, a substantial gap between conceptualization and practical implementation remains, largely attributed to low thermal energy conversion efficiency of TEG devices. To bridge this gap and meet the requisites of practical application, a feasible strategy involves the incorporation of a substantial number of p-n junctions within a confined unit volume. However, the manufacturing of high-density TEG p-n junctions presents a formidable challenge. The prevalent solution often leads to large device sizes to accommodate enough p-n junctions, consequently complicating integration with solar cells. Recently, the adoption of 3D printing technology has emerged as a promising solution to address this challenge by fabricating high-density p-n arrays. Despite this, further developmental efforts are necessary. Presently, the primary focus is on the 3D printing of vertically layered TEG devices, wherein p-n junction density remains constrained by spatial limitations and the constraints of 3D printing techniques. This study proposes a novel device configuration featuring horizontally arrayed p-n junctions of Bi2Te3. The structural design of the device is subjected to simulation through the Finite Element Method (FEM) within COMSOL Multiphysics software. Various device configurations are simulated to identify optimal device structure. Based on the simulation results, a new TEG device is fabricated utilizing 3D Selective laser melting (SLM) printing technology. Fusion 360 facilitates the translation of the COMSOL device structure into a 3D print file. The horizontal design offers a unique advantage, enabling the fabrication of densely packed, three-dimensional p-n junction arrays. The fabrication process entails printing a singular row of horizontal p-n junctions using the 3D SLM printing technique in a single layer. Subsequently, successive rows of p-n junction arrays are printed within the same layer, interconnected by thermally conductive copper. This sequence is replicated across multiple layers, separated by thermal insulating glass. This integration created in a highly compact three-dimensional TEG device with high density p-n junctions. The fabricated TEG device is then attached to the bottom of the solar cell using thermal glue. The whole device is characterized, with output data closely matching with COMSOL simulation results. Future research endeavors will encompass the refinement of thermoelectric materials. This includes the advancement of high-resolution 3D printing techniques tailored to diverse thermoelectric materials, along with the optimization of material microstructures such as porosity and doping. The objective is to achieve an optimal and highly integrated PV-TEG device that can substantially increase the solar energy harvest efficiency.

Keywords: thermoelectric, finite element method, 3d print, energy conversion

Procedia PDF Downloads 71

Authors: Cora Fernandez Dacosta, John A. Posada, Andrea Ramirez

Abstract:

The biodegradable family of polymers polyhydroxyalkanoates are interesting substitutes for convectional fossil-based plastics. However, the manufacturing and environmental impacts associated with their production via intracellular bacterial fermentation are strongly dependent on the raw material used and on energy consumption during the extraction process, limiting their potential for commercialization. Industrial wastewater is studied in this paper as a promising alternative feedstock for waste valorization. Based on results from laboratory and pilot-scale experiments, a conceptual process design, techno-economic analysis and life cycle assessment are developed for the large-scale production of the most common type of polyhydroxyalkanoate, polyhydroxbutyrate. Intracellular polyhydroxybutyrate is obtained via fermentation of microbial community present in industrial wastewater and the downstream processing is based on chemical digestion with surfactant and hypochlorite. The economic potential and environmental performance results help identifying bottlenecks and best opportunities to scale-up the process prior to industrial implementation. The outcome of this research indicates that the fermentation of wastewater towards PHB presents advantages compared to traditional PHAs production from sugars because the null environmental burdens and financial costs of the raw material in the bioplastic production process. Nevertheless, process optimization is still required to compete with the petrochemicals counterparts.

Keywords: circular economy, life cycle assessment, polyhydroxyalkanoates, waste valorization

Procedia PDF Downloads 459

Authors: S. Lakel, F. Elhamra, M. Ibrir, K. Almi

Abstract:

There is a growing interest in Zn1-xBexO (ZBO)/ZnO hetero structures and quantum wells since the band gap energy of Zn1-xBexO solid solutions can be turned over a very large range (3.37–10.6 eV) as a function of the Be composition. ZBO/ZnO has been utilized in ultraviolet light emission diodes and lasers, and may find applications as active elements of various other electronic and optoelectronic devices. Band gap engineering by Be substitution enables the facile preparation of barrier layers and quantum wells in device structures. In addition, ZnO and its ternary alloys, as piezoelectric semiconductors, have been used for high-frequency surface acoustic wave devices in wireless communication systems due to their high acoustic velocities and large electromechanical coupling. However, many important parameters such as elastic constants, bulk modulus, Young’s modulus and band-gap bowing. First-principles calculations of the structural, electrical and elastic properties of Zn1-xBexO as a function of the Be concentration x have been performed within density functional theory using norm-conserving pseudopotentials and local density approximation (LDA) for the exchange and correlation energy. The alloys’ lattice constants may deviate from the Vegard law. As Be concentration increases, the elastic constants, the bulk modulus and Young’s modulus of the alloys increase, the band gap increases with increasing Be concentration and Zn1-xBexO alloys have direct band. Our calculated results are in good agreement with experimental data and other theoretical calculations.

Keywords: DFT calculation, norm-conserving pseudopotentials, ZnBeO alloys, ZnO

Procedia PDF Downloads 524

Authors: Babagana Mohammed, Fidelis Patrick Afangide

Abstract:

This research investigated the possibility of using waste low-dense polyethylene and waste plastic bottles for the production of interlock pavement blocks. In many parts of the world, interlock pavement block is used widely as modern day solution to outdoor flooring applications and the blocks have different shapes, sizes and colours suiting the imagination of landscape architects. Using suitable and conventional mould having a 220 x 135 x 50 mm³ shape, the interlock blocks were produced. The material constituents of the produced blocks were waste low-dense polyethylene and waste plastic bottles mixed in varying, respective percentage-weight proportions of; 100%+0%, 75%+25%, 50%+50% and 25%+75%. The blocks were then tested for unconfined compressive strength and water absorption properties. The test results compared well with those of conventional concrete interlock blocks and the research demonstrates the possibility of value recovery from the waste streams which are currently dumped in open-spaces thereby affecting the environment.

Keywords: pavement blocks, polyethylene, plastic bottle, wastes, valorization

Procedia PDF Downloads 407

Authors: Flaviu Mihai Frigura-Lliasa, Andreea Anamaria Anghel, Attila Simo

Abstract:

Due to the beauty, usefulness, science, constantly changing, constantly evolving features, and most of the time, mystery it involves, nature-based art is seen as a both modern and timeless direction that has been extensively used in design. The goal of the team's activities was to experiment with ways of fusing the two most common contemporary ways of referring to green installations, that is, either in a pure artistic or in an ecological manner, and creating a living, dynamic, interactive installation capable of both receiving and interpreting external factors, such as natural and human stimuli, that would not only determine some of the mechanism's presets. By consequent, a complex experiment made up of various research and project stages was elaborated in order to transform an idea into an actual interactive green installation within months thanks to the interaction, teamwork, and design processes undertaken throughout the academic years by both university lecturers and some of our students. The outcomes would lead to the development of a dynamic artwork called "Modgrew" as well as the introduction of experiment-based learning at the Timisoara Faculty of Architecture and Urban Planning, as well as at the Faculty of Electrical and Power Engineering, for the green wall automation issues.

Keywords: green design, living walls, modular structure, interactive proof of concept

Procedia PDF Downloads 82

Authors: Farzad Jalilian, Mehdi Mirzaei Alavijeh

Abstract:

Background: E-interventions as a universal approach to prevent a high-risk behavior, such as alcohol drinking. This study was conducted to evaluate web-based alcohol drinking preventative intervention efficiency among medical university students in Iran. Methods: Overall, 150 freshman and sophomore male student’s college students participated in this study as intervention and control group. This was a longitudinal randomized pre- and post-test series control group design panel study to implement a behavior modification based intervention to alcohol drinking prevention among college students. Cross-tabulation, t-test, repeated measures, and GEE by using SPSS statistical package, version 21 was used for the statistical analysis. The participants were followed up for 6 months with data collection scheduled at baseline, 3 and 6 months. The primary outcomes are attitude, self-control, and sensation seeking. Furthermore, the secondary outcome is comparing alcohol drinking among the study groups. Results: It was found significant reduce in average response for an attitude towards alcohol drinking and sensation seeking among intervention group (P < 0.05). But after intervention not significant difference between intervention and control group of improve self-control and reduce alcohol drinking (P > 0.05). Conclusion: Our intervention has been accompanied with reducing alcohol use rate. These findings indicate that e-intervention may be effectiveness approach to address the alcohol prevention among college students.

Keywords: e-interventions, alcohol drinking, students, Iran

Procedia PDF Downloads 417

Authors: Behbood Maashkar

Abstract:

One of the principles for societies’ development is the requirement to consider past experiences. Man should always take advantage of the predecessor’s experiences and analyze their works and methods. The predecessors have had a more friendly relationship with nature and their lives less damaged the nature, and it is one of the elements of green building. One of the things the ancients have observed in regard to green building in their houses, stores, sacred places, etc. was using wind-catchers as an air conditioning and cooling system which can be considered as the first foundations of green building. In designing houses Iranian architects have paid a great attention to the factor of making use of more shaded area in hot season and insulation of wall and ceiling against influence of hot weather and also air circulation inside the building. In order to circulate the air inside closed spaces and decrease the temperature, they have considered different winds which blow in Iran and its effective power, and in order to make use of it they invented wind catcher. Direction of wind blow and its height from the earth as well as the time and duration of wind blow and other factors have been effective in making different types of wind catchers. Using wind catchers has been and is prevalent mainly in central and south regions of Iran, coastal areas of Persian Gulf, and Khorasan, especially in cities like Yazd, Kashan, Bam, Abarghoo, Jahrom, and Tabas.

Keywords: environment pollution, green building, Iran, wind catchers

Procedia PDF Downloads 252