Search results for: Cross wall

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, struts.

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

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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: Insulator, coating, climate, energy consumption.

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Authors: Ishtiaq A. Chaudhry, Zia R. Tahir

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Experimental investigation has been carried out towards understanding the complex fluid dynamics involved in the interaction of vortical structures with zero pressure gradient boundary layer. A laminar boundary layer is produced on the flat plate placed in the water flume and the synthetic jet actuator is deployed on top of the plate at a definite distance from the leading edge. The synthetic jet actuator has been designed in such a way that the to and fro motion of the diaphragm is maneuvered at will by varying the operating parameters to produce the typical streamwise vortical structures namely hairpin and tilted vortices. PIV measurements are made on the streamwise plane normal to the plate to evaluate their interaction with the near wall fluid.

Keywords: Boundary layer, synthetic jet actuator, flow separation control, vortical structures.

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Authors: Kyung Joo Yi, Seung Wook Baek, Sung Nam Lee, Man Young Kim, Won Cheol Kim, Gun Yung Go

Abstract:

In order to enhance the aircraft survivability, the infrared signatures emitted by hot engine parts should be determined exactly. For its reduction it is necessary for the rear fuselage temperature to be decreased. In this study, numerical modeling of flow fields and heat transfer characteristics of an aircraft nozzle is performed and its temperature distribution along each component wall is predicted. The radiation shield is expected to reduce the skin temperature of rear fuselage. The effect of material characteristic of radiation shield on the heat transfer is also investigated. Through this numerical analysis, design parameters related to the susceptibility of aircraft are examined.

Keywords: Infrared signature, Nozzle flow, Radiation shield, Rear fuselage temperature, Susceptibility

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Authors: Seung-Hun Kim, Changwoo Park

Abstract:

In this paper, we present a localization of a mobile robot with localization modules which have two ceiling-view cameras in indoor environments. We propose two kinds of localization method. The one is the localization in the local space; we use the line feature and the corner feature between the ceiling and wall. The other is the localization in the large space; we use the natural features such as bulbs, structures on the ceiling. These methods are installed on the embedded module able to mount on the robot. The embedded module has two cameras to be able to localize in both the local space and the large spaces. The experiment is practiced in our indoor test-bed and a government office. The proposed method is proved by the experimental results.

Keywords: Robot, Localization, Indoor, Ceiling vision, Local space, Large space, Complex space.

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Authors: Carmen Grigoraş, Victor Grigoraş, Daniela Boişteanu

Abstract:

The standard investigational method for obstructive sleep apnea syndrome (OSAS) diagnosis is polysomnography (PSG), which consists of a simultaneous, usually overnight recording of multiple electro-physiological signals related to sleep and wakefulness. This is an expensive, encumbering and not a readily repeated protocol, and therefore there is need for simpler and easily implemented screening and detection techniques. Identification of apnea/hypopnea events in the screening recordings is the key factor for the diagnosis of OSAS. The analysis of a solely single-lead electrocardiographic (ECG) signal for OSAS diagnosis, which may be done with portable devices, at patient-s home, is the challenge of the last years. A novel artificial neural network (ANN) based approach for feature extraction and automatic identification of respiratory events in ECG signals is presented in this paper. A nonlinear principal component analysis (NLPCA) method was considered for feature extraction and support vector machine for classification/recognition. An alternative representation of the respiratory events by means of Kohonen type neural network is discussed. Our prospective study was based on OSAS patients of the Clinical Hospital of Pneumology from Iaşi, Romania, males and females, as well as on non-OSAS investigated human subjects. Our computed analysis includes a learning phase based on cross signal PSG annotation.

Keywords: Artificial neural networks, feature extraction, obstructive sleep apnea syndrome, pattern recognition, signalprocessing.

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Authors: S. Ismail, Z. Yaacob

Abstract:

The main aim of this research is to study the possible use of recycled fine aggregate made from waste rubble wall to substitute partially for the natural sand used in the production of cement and sand bricks. The bricks specimens were prepared by using 100% natural sand; they were then replaced by recycled fine aggregate at 25, 50, 75, and 100% by weight of natural sand. A series of tests was carried out to study the effect of using recycled aggregate on the physical and mechanical properties of bricks, such as density, drying shrinkage, water absorption characteristic, compressive and flexural strength. Test results indicate that it is possible to manufacture bricks containing recycled fine aggregate with good characteristics that are similar in physical and mechanical properties to those of bricks with natural aggregate, provided that the percentage of recycled fine aggregates is limited up to 50-75%.

Keywords: Bricks, cement, recycled aggregate, sand

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Authors: Somchai Supattarakul, Anya Khanthavit

Abstract:

This study aims at providing empirical evidence on a comparison of two equity valuation models: (1) the dividend discount model (DDM) and (2) the residual income model (RIM), in estimating equity values of Thai firms during 1995-2004. Results suggest that DDM and RIM underestimate equity values of Thai firms and that RIM outperforms DDM in predicting cross-sectional stock prices. Results on regression of cross-sectional stock prices on the decomposed DDM and RIM equity values indicate that book value of equity provides the greatest incremental explanatory power, relative to other components in DDM and RIM terminal values, suggesting that book value distortions resulting from accounting procedures and choices are less severe than forecast and measurement errors in discount rates and growth rates. We also document that the incremental explanatory power of book value of equity during 1998-2004, representing the information environment under Thai Accounting Standards reformed after the 1997 economic crisis to conform to International Accounting Standards, is significantly greater than that during 1995-1996, representing the information environment under the pre-reformed Thai Accounting Standards. This implies that the book value distortions are less severe under the 1997 Reformed Thai Accounting Standards than the pre-reformed Thai Accounting Standards.

Keywords: Dividend Discount Model, Equity Valuation Model, Residual Income Model, Thai Stock Market

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Authors: K. Vakhshouri, M.M. Y. Motamed Hashemi

Abstract:

A rigorous two-dimensional model is developed for simulating the operation of a less-investigated type steam reformer having a considerably lower operating Reynolds number, higher tube diameter, and non-availability of extra steam in the feed compared with conventional steam reformers. Simulation results show that reasonable predictions can only be achieved when certain correlations for wall to fluid heat transfer equations are applied. Due to severe operating conditions, in all cases, strong radial temperature gradients inside the reformer tubes have been found. Furthermore, the results show how a certain catalyst loading profile will affect the operation of the reformer.

Keywords: Steam reforming, direct reduction, heat transfer, two-dimensional model, simulation.

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Authors: Hairulliza M. Judi, Soon Y. Chee

Abstract:

This paper discusses the landscape design that could increase energy efficiency in a house. By planting trees in a house compound, the tree shades prevent direct sunlight from heating up the building, and it enables cooling off the surrounding air. The requirement for air-conditioning could be minimized and the air quality could be improved. During the life time of a tree, the saving cost from the mentioned benefits could be up to US $ 200 for each tree. The project intends to visually describe the landscape design in a house compound that could enhance energy efficiency and consequently lead to energy saving. The house compound model was developed in three dimensions by using AutoCAD 2005, the animation was programmed by using LightWave 3D softwares i.e. Modeler and Layout to display the tree shadings in the wall. The visualization was executed on a VRML Pad platform and implemented on a web environment.

Keywords: Tree planting, tree shading, energy efficiency, visualization.

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Authors: Reinaldo Biscaro, Luciano R. Ferreira, Leonardo C. Biscaro, Raphael C. Biscaro, Isabela S. Vasconcelos, Laura C. R. Ferreira, Cristiano M. Galhardi, Erica P. Baciuk

Abstract:

Introduction: The present study had the objective to present the profile of workers with shoulder disorders related to labor lawsuits in Brazil. The study analyzed the association between the worker’s health and the actions performed by the companies related to injured professional. The research method performed a retrospective, cross-sectional and quantitative database analysis. The documents of labor lawsuits with shoulder injury registered at the Regional Labor Court in the 15^th region (Campinas - São Paulo) were submitted to the medical examination and evaluated during the period from 2012 until 2015. The data collected were age, gender, onset of symptoms, length of service, current occupation, type of shoulder injury, referred complaints, type of acromion, associated or related diseases, company actions as CAT (workplace accident communication), compliance of NR7 by the organization (Environmental Risk Prevention Program - PPRA and Medical Coordination Program in Occupational Health - PCMSO). Results: From the 93 workers evaluated, there was a prevalence of men (58.1%), with a mean age of 42.6 y-o, and 54.8% were included in the age group 35-49 years. Regarding the length of work time in the company, 66.7% have worked for more than 5 years. There was an association between gender and current occupational status (p < 0.005), with predominance of women in household occupation (13 vs. 2) and predominance of unemployed men in job search situation (24 vs. 10) and reintegrated to work by judicial decision (8 vs. 2). There was also a correlation between pain and functional limitation (p < 0.01). There was a positive association of PPRA with the complaint of functional limitation and negative association with pain (p < 0.04). There was also a correlation between the sedentary lifestyle and the presence of PCMSO and PPRA (p < 0.04), and the absence of CAT in the companies (p < 0.001). It was concluded that the appearance or aggravation of osseous and articular shoulder pathologies in workers who have undertaken labor law suits seem to be associated with individual habits or inadequate labor practices. These data can help preventing the occurrence of these lesions by implementing local health promotion policies at work.

Keywords: Work-related accidents, cross-sectional study, shoulder lesions, labor lawsuits.

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Authors: Saad Nahi Saleh

Abstract:

This paper presents the prediction of air flow, humidity and temperature patterns in a co-current pilot plant spray dryer fitted with a pressure nozzle using a three dimensional model. The modelling was done with a Computational Fluid Dynamic package (Fluent 6.3), in which the gas phase is modelled as continuum using the Euler approach and the droplet/ particle phase is modelled by the Discrete Phase model (Lagrange approach).Good agreement was obtained with published experimental data where the CFD simulation correctly predicts a fast downward central flowing core and slow recirculation zones near the walls. In this work, the effects of the air flow pattern on droplets trajectories, residence time distribution of droplets and deposition of the droplets on the wall also were investigated where atomizing of maltodextrin solution was used.

Keywords: Spray, CFD, multiphase, drying, droplet, particle.

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Authors: Salwa Hagag Abdelaziz, Naglaa Fathy Youssef, Nadia Abdel Latif Hassan, Rasha Wesam Abdel Rahman

Abstract:

Breast cancer is considered as a substantial health concern and practicing mammography screening [MS] is important in minimizing its related morbidity. So it is essential to have a better understanding of breast cancer screening behaviors of women and factors that influence utilization of them. The aim of this study is to identify the factors that are linked to MS behaviors among the Egyptian women. A cross-sectional descriptive design was carried out to provide a snapshot of the factors that are linked to MS behaviors. A convenience sample of 311 women was utilized and all eligible participants admitted to the Women Imaging Unit who are 40 years of age or above, coming for mammography assessment, not pregnant or breast feeding and who accepted to participate in the study were included. A structured questionnaire was developed by the researchers and contains three parts; Socio-demographic data; Motivating factors associated with MS; and association between MS and model of behavior change. The analyzed data indicated that most of the participated women (66.6%) belonged to the age group of 40- 49.A high proportion of participants (58.1%) of group having previous MS influenced by their neighbors to practice MS, whereas 32.7 % in group not having previous MS were influenced by family members which indicated significant differences (P <0.05). Doctors and media shown to be the least influence of others to practice MS. Women with intention to have a future mammogram had higher OR (1.404) for practicing MS compared with women with no intention. Further studies are needed to examine the relation between Transtheoretical Model [TTM] and practicing MS.

Keywords: Breast cancer, mammography, screening behaviors.

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Authors: Nina Øystad-Larsen, Miran Cemalovic, Amir M. Kaynia

Abstract:

The nonlinear static and dynamic analysis procedures presented in EN 1998-1 for the structural response of a RC wall-frame building are assessed. The structure is designed according to the guidelines for high ductility (DCH) in 1998-1. The finite element packages SeismoStruct and OpenSees are utilized and evaluated. The structural response remains nearly in the elastic range even though the building was designed for high ductility. The overstrength is a result of oversized and heavily reinforced members, with emphasis on the lower storey walls. Nonlinear response history analysis in the software packages give virtually identical results for displacements.

Keywords: Behaviour factor, Dual system, OpenSEES, Overstrength, SeismoStruct.

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Authors: Hazem M. El-Bakry

Abstract:

In this paper, an automatic determination algorithm for nuclear magnetic resonance (NMR) spectra of the metabolites in the living body by magnetic resonance spectroscopy (MRS) without human intervention or complicated calculations is presented. In such method, the problem of NMR spectrum determination is transformed into the determination of the parameters of a mathematical model of the NMR signal. To calculate these parameters efficiently, a new model called modified Hopfield neural network is designed. The main achievement of this paper over the work in literature [30] is that the speed of the modified Hopfield neural network is accelerated. This is done by applying cross correlation in the frequency domain between the input values and the input weights. The modified Hopfield neural network can accomplish complex dignals perfectly with out any additinal computation steps. This is a valuable advantage as NMR signals are complex-valued. In addition, a technique called “modified sequential extension of section (MSES)" that takes into account the damping rate of the NMR signal is developed to be faster than that presented in [30]. Simulation results show that the calculation precision of the spectrum improves when MSES is used along with the neural network. Furthermore, MSES is found to reduce the local minimum problem in Hopfield neural networks. Moreover, the performance of the proposed method is evaluated and there is no effect on the performance of calculations when using the modified Hopfield neural networks.

Keywords: Hopfield Neural Networks, Cross Correlation, Nuclear Magnetic Resonance, Magnetic Resonance Spectroscopy, Fast Fourier Transform.

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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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Authors: D. Kim

Abstract:

Numerical simulations are performed for laminar continuous and pulsed jets impinging on a surface in order to investigate the effects of pulsing frequency on the heat transfer characteristics. The time-averaged Nusselt number of pulsed jets is larger in the impinging jet region as compared to the continuous jet, while it is smaller in the outer wall jet region. At the stagnation point, the mean and RMS Nusselt numbers become larger and smaller, respectively, as the pulsing frequency increases. Unsteady behaviors of vortical fluid motions and temperature field are also investigated to understand the underlying mechanisms of heat transfer enhancement.

Keywords: Pulsed slot jet, impingement, pulsing frequency, heat transfer enhancement.

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Authors: S. Vijayakumar, R. Vinoth, K. Abilash, P. Praveen

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Effects of insertion of coiled wire in juxtaposition with twisted tapes on heat transfer rate and solar radiation without disturbing the flow inside the riser tubes in a solar flat plate collector is experimentally reconnoitered in this present work. The wire coil used as a turbulator is placed inside the riser tube while the twisted tape is inserted into the wire coil to create a continuous swirling flow along the tube wall. The results of the heat transfer have been compared well with the available results. The heat transfer rate in the collector has been found to be increased by 18% to 70%. Solar water heaters having inserts in the flow tubes perform better than the conventional plain ones. It has been observed that heat losses are reduced consequently increasing the thermal performance about 30% over the plain water heaters under the same operating conditions. The effect of twisted tape with wire coils, flow Reynolds number, and the intensity of solar radiation on the thermal performance of the solar water heater has been presented. Effects of insertion of coiled wire in juxtaposition with twisted tapes on heat transfer rate and solar radiation without disturbing the flow inside the riser tubes in a solar flat plate collector is experimentally reconnoitered in this present work. The wire coil used as a turbulator is placed inside the riser tube while the twisted tape is inserted into the wire coil to create a continuous swirling flow along the tube wall. The results of the heat transfer have been compared well with the available results. The heat transfer rate in the collector has been found to be increased by 18% to 70%. Solar water heaters having inserts in the flow tubes perform better than the conventional plain ones. It has been observed that heat losses are reduced consequently increasing the thermal performance about 30% over the plain water heaters under the same operating conditions. The effect of twisted tape with wire coils, flow Reynolds number, and the intensity of solar radiation on the thermal performance of the solar water heater has been presented.

Keywords: Solar Flat Plate Collector, Heat Transfer, Twisted tape, Wire coiled turbulators

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Authors: Atilla Akpinar, Basri Celik, Suleyman Ciftci

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In this paper, we deal with finite projective Klingenberg plane M (A) coordinatized by local ring A := Zq+Zq E (where prime power q = p', e0 Z q and 62 = 0). So, we get some combinatorical results on 6-figures. For example, we show that there exist p — 1 6-figure classes in M(A).

Keywords: finite Klingenberg plane, 6-figure, ratio of 6-figure, cross-ratio.

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Authors: Barzin Gavtash, Khalid Hussain, Mohammad Layeghi, Saeed Sadeghi Lafmejani

Abstract:

This research aims at modeling and simulating the effects of nanofluids on cylindrical heat pipes thermal performance using the ANSYS-FLUENT CFD commercial software. The heat pipe outer wall temperature distribution, thermal resistance, liquid pressure and axial velocity in presence of suspended nano-scaled solid particle (i.e. Cu, Al2O3 and TiO2) within the fluid (water) were investigated. The effect of particle concentration and size were explored and it is concluded that the thermal performance of the heat pipe is improved when using nanofluid as the system working fluid. Additionally, it was observed that the thermal resistance of the heat pipe drops as the particle concentration level increases and particle radius decreases.

Keywords: CFD, Heat Pipe, Nanofluid, Thermal resistance

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Authors: Orly Redlich

Abstract:

Since the establishment of the state of Israel, and as a result of various events that led to it, Jewish citizens and Arab citizens of the state have been in constant conflict, which finds its expression in most levels of life. Therefore, the attitude of one group member to the other group members is mostly tense, loaded, and saturated with mutual suspicion. Within this reality, in many higher education institutions in Israel, Jews and Arabs meet with each other intensively and for several years. For some students, this is their first opportunity for a meaningful cross-cultural encounter. These intercultural encounters, which allow positive interactions between members of different cultural groups, may contribute to the formation of "intercultural competence" which means long-term change in knowledge, attitudes, and behavior towards 'the other culture'. The current study examined the concept of the ‘other’ among Jewish and Arab students studying together and their "intercultural competence". The study also examined whether there is a difference in the perception of the ‘other’ between students studying in different academic programs, and between students taking academic courses on multiculturalism. This quantitative study was conducted among 274 Arab and Jewish students studying together, for bachelors or master's degree, in various academic programs at the Israel Academic College of Ramat-Gan. The background data of the participants are varied, in terms of religion, origin, religiosity, employment status, living area, and marital status. The main hypothesis is that academic, social, and intercultural encounters between Jewish and Arab students, who attend college together, will be a significant factor in building "intercultural competence". Additionally, the existence of "intercultural competence" has been linked to demographic characteristics of the students, as well as the nature of intercultural encounters between Jews and Arabs in a higher education institution. The dependent variables were measured by a self-report questionnaire, using the components of '"intercultural competence"' among students, which are: 1. Cognitive knowledge of the ‘others’, 2. Feelings towards the ‘others’, 3. Change in attitudes towards the 'others', and 4. Change in behavior towards the ‘others’. The findings indicate a higher "intercultural competence" among Arab students than Jews; it was also found higher level of "intercultural competence" among Educational Counseling students than the other respondents. The importance of this research lies in finding the means to develop "intercultural competence" among Jewish and Arab students, which may reduce prejudice and stereotypes towards the other culture and may even prevent occurrences of alienation and violence in cross-cultural encounters in Israel.

Keywords: Cross-cultural learning, "intercultural competence", Jewish and Arab students, multiculturalism.

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Authors: Arash Karimipour, M. Afrand, M. M. Bazofti

Abstract:

The periodic mixed convection of a water-copper nanofluid inside a rectangular cavity with aspect ratio of 3 is investigated numerically. The temperature of the bottom wall of the cavity is assumed greater than the temperature of the top lid which oscillates horizontally with the velocity defined as u = u0 sin (ω t). The effects of Richardson number, Ri, and volume fraction of nanoparticles on the flow and thermal behavior of the nanofluid are investigated. Velocity and temperature profiles, streamlines and isotherms are presented. It is observed that when Ri < 1, heat transfer rate is much greater than when Ri > 1. The higher value of Ri corresponds to a lower value of the amplitude of the oscillation of Num in the steady periodic state. Moreover, increasing the volume fraction of the nanoparticles increases the heat transfer rate.

Keywords: Nanofluid, Top lid oscillation, Mixed convection, Volume fraction

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Authors: Motahar Reza, Anadi Sankar Gupta

Abstract:

An analysis is made of the flow of an incompressible viscoelastic fluid (of small memory) over a porous plate subject to suction or blowing. It is found that velocity at a point increases with increase in the elasticity in the fluid. It is also shown that wall shear stress depends only on suction and is also independent of the material of fluids. No steady solution for velocity distribution exists when there is blowing at the plate. Temperature distribution in the boundary layer is determined and it is found that temperature at a point decreases with increase in the elasticity in the fluid.

Keywords: Viscoelastic fluid, Flow past a porous plate, Heat transfer

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Authors: M. Amoura, M. Alloti, A. Mouassi, N. Zeraibi

Abstract:

Heat transfer behavior of three different types of nanofluids flowing through a horizontal tube under laminar regime has been investigated numerically. The wall of tube is maintained at constant temperature. Al₂O₃-water, CuO-water and TiO₂-water are used with different Reynolds number and different volume fraction. The numerical results of heat transfer indicate that the Nusselt number of nanofluids is larger than that of the base fluid. The Pressure loss coefficient decreases by increasing Reynolds number for all types of nanofluids. Results of Nusselt number enhancement and pressure loss coefficient enhancement indicate that Al₂O₃ nanoparticules give the best results in term of thermal-hydrolic properties.

Keywords: Heat transfer, Laminar flow, Nanofluid, Numerical study.

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Authors: H K Lakshminarayana, J S Bhat, H M Mahesh

Abstract:

A new estimator for evolutionary spectrum (ES) based on short time Fourier transform (STFT) and modified group delay function (MGDF) by signal decomposition (SD) is proposed. The STFT due to its built-in averaging, suppresses the cross terms and the MGDF preserves the frequency resolution of the rectangular window with the reduction in the Gibbs ripple. The present work overcomes the magnitude distortion observed in multi-component non-stationary signals with STFT and MGDF estimation of ES using SD. The SD is achieved either through discrete cosine transform based harmonic wavelet transform (DCTHWT) or perfect reconstruction filter banks (PRFB). The MGDF also improves the signal to noise ratio by removing associated noise. The performance of the present method is illustrated for cross chirp and frequency shift keying (FSK) signals, which indicates that its performance is better than STFT-MGDF (STFT-GD) alone. Further its noise immunity is better than STFT. The SD based methods, however cannot bring out the frequency transition path from band to band clearly, as there will be gap in the contour plot at the transition. The PRFB based STFT-SD shows good performance than DCTHWT decomposition method for STFT-GD.

Keywords: Evolutionary Spectrum, Modified Group Delay, Discrete Cosine Transform, Harmonic Wavelet Transform, Perfect Reconstruction Filter Banks, Short Time Fourier Transform.

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Authors: Shiyun Liu

Abstract:

Radiant heating systems work fundamentally differently from air systems by taking advantage of both radiant and convective heat transfer to remove space heating load. There are rare studies on differences of heating systems between all-air system and radiant floor system. This paper uses the method of simulation based on state-space to calculate the indoor temperature and wall temperature of each system and shows how the dynamic heat transfer in rooms conditioned by a radiant system is different from an air system. Then this paper analyses the changes of indoor temperature of these two systems, finding out the differences between all-air heating system and radiant floor heating system to help the designer choose a more suitable heating system.

Keywords: Radiant floor, all-air system, thermal comfort, simulation, heating system.

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Authors: Ahmet Turer

Abstract:

Middle-gate is located in Hasankeyf, Batman dating back to 1800 BC and is one of the important historical structures in Turkey. The ancient structure has suffered major structural cracks due to aging as well as lateral pressure of a cracked rock which is predicted to be about 100 tons. The existing support system was found to be inadequate to support the load especially after a recent rock fall in the close vicinity. Concerns were increased since the existing support system that is integral with a damaged and cracked gate wall needed to be replaced by a new support system. The replacement process must be carefully monitored by crackmeters and control mechanisms should be integrated to prevent cracks to expand while the same crack width needs to be maintained after the operation. The control system and actions taken during the intervention are explained in this paper.

Keywords: structural control, crack width, replacement, support

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Authors: Muhammad Imran, Iqra Basit, Mobushir Riaz Khan, Sajid Rasheed Ahmad

Abstract:

The present study investigates the space-time impact of climate change on the rice crop calendar in tropical Gujranwala, Pakistan. The climate change impact was quantified through the climatic variables, whereas the existing calendar of the rice crop was compared with the phonological stages of the crop, depicted through the time series of the Normalized Difference Vegetation Index (NDVI) derived from Landsat data for the decade 2005-2015. Local maxima were applied on the time series of NDVI to compute the rice phonological stages. Panel models with fixed and cross-section fixed effects were used to establish the relation between the climatic parameters and the time-series of NDVI across villages and across rice growing periods. Results show that the climatic parameters have significant impact on the rice crop calendar. Moreover, the fixed effect model is a significant improvement over cross-sectional fixed effect models (R-squared equal to 0.673 vs. 0.0338). We conclude that high inter-annual variability of climatic variables cause high variability of NDVI, and thus, a shift in the rice crop calendar. Moreover, inter-annual (temporal) variability of the rice crop calendar is high compared to the inter-village (spatial) variability. We suggest the local rice farmers to adapt this change in the rice crop calendar.

Keywords: Landsat NDVI, panel models, temperature, rainfall.

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Authors: Karel Frana, Jianshun S. Zhang, Milos Muller

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The indoor airflow with a mixed natural/forced convection was numerically calculated using the laminar and turbulent approach. The Boussinesq approximation was considered for a simplification of the mathematical model and calculations. The results obtained, such as mean velocity fields, were successfully compared with experimental PIV flow visualizations. The effect of the distance between the cooled wall and the heat exchanger on the temperature and velocity distributions was calculated. In a room with a simple shape, the computational code OpenFOAM demonstrated an ability to numerically predict flow patterns. Furthermore, numerical techniques, boundary type conditions and the computational grid quality were examined. Calculations using the turbulence model k-omega had a significant effect on the results influencing temperature and velocity distributions.

Keywords: natural and forced convections, numerical simulations, indoor airflows.

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Authors: Yongseok Kwon, Woowon Jeong, Eunjin Cho, Sangkug Chung, Kyehan Rhee

Abstract:

Steady streaming flow fields induced by a 500 mm bubble oscillating at 12 kHz were measured using microscopic particle image velocimetry (PIV). The accuracy of velocity measurement using a micro PIV system was checked by comparing the measured velocity fields with the theoretical velocity profiles in fully developed laminar flow. The steady streaming flow velocities were measured in the sagittal plane of the bubble attached on the wall. Measured velocity fields showed upward jet flow with two symmetric counter-rotating vortices, and the maximum streaming velocity was about 12 mm/s, which was within the velocity ranges measured by other researchers. The measured streamlines were compared with the analytical solution, and they also showed a reasonable agreement.

Keywords: Oscillating bubble, Particle-Image-Velocimetry microstreaming.

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