Search results for: finite element analyses (FEA)

Authors: I. Szer, J. Szer, M. Pieńko, A. Robak, P. Jamińska-Gadomska

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Work at height, such as construction works on scaffoldings, is associated with a considerable risk. Scaffolding workers are usually exposed to changing weather conditions what can additionally increase the risk of dangerous situations. Therefore, it is very important to foresee the risk of adverse conditions to which the worker may be exposed. The data from meteorological stations may be used to asses this risk. However, the dependency between weather conditions on a scaffolding and in the vicinity of meteorological station, should be determined. The paper presents an analysis of two selected environmental parameters which have influence on the behavior of workers – air temperature and wind speed. Measurements of these parameters were made between April and November of 2016 on ten scaffoldings located in different parts of Poland. They were compared with the results taken from the meteorological stations located closest to the studied scaffolding. The results gathered from the construction sites and meteorological stations were not the same, but statistical analyses have shown that they were correlated.

Keywords: Scaffoldings, health and safety at work, temperature, wind speed.

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Authors: Asfaw Gezae Daful

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In the present study, two distinctly different approaches are followed for modeling of reactive distillation column, the equilibrium stage model and the nonequilibrium stage model. These models are simulated with a computer code developed in the present study using MATLAB programming. In the equilibrium stage models, the vapor and liquid phases are assumed to be in equilibrium and allowance is made for finite reaction rates, where as in the nonequilibrium stage models simultaneous mass transfer and reaction rates are considered. These simulated model results are validated from the experimental data reported in the literature. The simulated results of equilibrium and nonequilibrium models are compared for concentration, temperature and reaction rate profiles in a reactive distillation column for Methyl Tert Butyle Ether (MTBE) production. Both the models show similar trend for the concentration, temperature and reaction rate profiles but the nonequilibrium model predictions are higher and closer to the experimental values reported in the literature.

Keywords: Reactive Distillation, Equilibrium model, Nonequilibrium model, Methyl Tert-Butyl Ether

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Authors: Fareeha A., Irfan Z Qureshi

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Thrombosis can be life threatening, necessitating therefore its instant treatment. Hydergine, a nootropic agent is used as a cognition enhancer in stroke patients but relatively little is known about its anti-thrombolytic effect. To investigate this aspect, in vivo and ex vivo experiments were designed and conducted. Three groups of rats were injected 1.5mg, 3.0mg and 4.5mg hydergine intraperitonealy with and without prior exposure to fresh plasma. Positive and negative controls were run in parallel. Animals were sacrificed after 1.5hrs and BT, CT, PT, INR, APTT, plasma calcium levels were estimated. For ex vivo analyses, each 1ml blood aspirated was exposed to 0.1mg, 0.2mg, 0.3mg dose of hydergine with parallel controls. Parameters analyzed were as above. Statistical analysis was through one-way ANOVA. Dunken-s and Tukey-s tests provided intra-group variance. BT, CT, PT, INR and APTT increased while calcium levels dropped significantly (P<0.05). Ex vivo, CT, PT and APTT were elevated while plasma calcium levels lowered significantly (P<0.05). Our study suggests that hydergine may act as a thrombolytic agent but warrants further studies to elucidate this role of ergot mesylates.

Keywords: Hydergine, Coagulation assays, plasma calcium, ergot mesylates, thrombosis.

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Authors: Petr Homola, Roman Růžek

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Laser beam micro-drilling (LBMD) is one of the most important non-contact machining processes of materials that are difficult to machine by means oeqf conventional machining methods used in various industries. The paper is focused on LBMD knock-down effect on Ti-6Al-4V (Grade 5) titanium alloy sheets properties. Two various process configurations were verified with a focus on laser damages in back-structure parts affected by the process. The effects of the LBMD on the material properties were assessed by means of tensile and fatigue tests and fracture surface analyses. Fatigue limit of LBMD configurations reached a significantly lower value between 15% and 30% of the static strength as compared to the reference raw material with 58% value. The farther back-structure configuration gives a two-fold fatigue life as compared to the closer LBMD configuration at a given stress applied.

Keywords: Fatigue, fracture surface, laser beam micro-drilling, titanium alloy.

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Authors: Veli Ozbolat, Nehir Tokgoz, Besir Sahin

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Present study numerically investigates the flow field and heat transfer of water in two dimensional sinusoidal and rectangular corrugated wall channels. Simulations are performed for fully developed flow conditions at inlet sections of the channels that have 12 waves. The temperature of the input fluid is taken to be less than that temperature of wavy walls. The governing continuity, momentum and energy equations are numerically solved using finite volume method based on SIMPLE technique. The investigation covers Reynolds number in the rage of 100-1000. The effects of the distance between upper and lower corrugated walls are studied by varying Hmin/Hmax ratio from 0.3 to 0.5 for keeping wave length and wave amplitude values fixed for both geometries. The effects of the wall geometry, Reynolds number and the distance between walls on the flow characteristics, the local Nusselt number and heat transfer are studied. It is found that heat transfer enhancement increases by usage of corrugated horizontal walls in an appropriate Reynolds number regime and channel height.

Keywords: Corrugated Channel, CFD, Flow Characteristics, Heat Transfer.

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Authors: Fl. Loury, P. Sablonière, C. Lamoureux, G. Magnier, Th. Gutierrez

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A method is proposed to extract faithful representative patterns from data set of observations when they are suffering from non-negligible fluctuations. Supposing time interval between measurements to be extremely small compared to observation time, it consists in defining first a subset of intermediate time intervals characterizing coherent behavior. Data projection on these intervals gives a set of curves out of which an ideally “perfect” one is constructed by taking the sup limit of them. Then comparison with average real curve in corresponding interval gives an efficiency parameter expressing the degradation consecutive to fluctuation effect. The method is applied to sunlight data collected in a specific place, where ideal sunlight is the one resulting from direct exposure at location latitude over the year, and efficiency is resulting from action of meteorological parameters, mainly cloudiness, at different periods of the year. The extracted information already gives interesting element of decision, before being used for analysis of plant control.

Keywords: Base Input Reconstruction, Data Mining, Efficiency Factor, Information Pattern Operator.

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Authors: Nurcan Tuncbag, Turkan Haliloglu, Ozlem Keskin

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Understanding the cell's large-scale organization is an interesting task in computational biology. Thus, protein-protein interactions can reveal important organization and function of the cell. Here, we investigated the correspondence between protein interactions and function for the yeast. We obtained the correlations among the set of proteins. Then these correlations are clustered using both the hierarchical and biclustering methods. The detailed analyses of proteins in each cluster were carried out by making use of their functional annotations. As a result, we found that some functional classes appear together in almost all biclusters. On the other hand, in hierarchical clustering, the dominancy of one functional class is observed. In the light of the clustering data, we have verified some interactions which were not identified as core interactions in DIP and also, we have characterized some functionally unknown proteins according to the interaction data and functional correlation. In brief, from interaction data to function, some correlated results are noticed about the relationship between interaction and function which might give clues about the organization of the proteins, also to predict new interactions and to characterize functions of unknown proteins.

Keywords: Pair-wise protein interactions, DIP database, functional correlations, biclustering.

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Authors: Salahaldein Alsadey, Issa Amaish

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Recycled aggregates (RA) have the potential to compromise concrete performance, contributing to issues such as reduced strength and increased susceptibility to cracking. This study investigates the impact of sisal fiber (SF) on the mechanical properties of concrete, with the objective of utilizing SFs as a reinforcing element in concrete compositions containing natural aggregate and varying percentages (25%, 50%, and 75%) of coarse RA replacement. The investigation aims to discern the positive and negative effects on compressive and flexural strength, thereby assessing the viability of SF-reinforced recycled concrete in comparison to conventional concrete composed of natural aggregate without SF. Test results revealed that concrete samples incorporating SF exhibited elevated compressive and flexural strength. Comparative analysis of these strength values was conducted with reference to samples devoid of SF.

Keywords: Sustainable construction, construction materials, recycled aggregate, sisal fibers, compressive strength, flexural strength, eco-friendly concrete, natural fiber composites, recycled materials, construction waste management.

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Authors: M. Boumaza, Y. Bakhabkhi

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Water recycling represents an important challenge for many countries, in particular in countries where this natural resource is rare. On the other hand, in many operations, water is used as a cooling medium, as a high proportion of water consumed in industry is used for cooling purposes. Generally this water is rejected directly to the nature. This reject will cause serious environment damages as well as an important waste of this precious element.. On way to solve these problems is to reuse and recycle this warm water, through the use of natural cooling medium, such as air in a heat exchanger unit, known as a cooling tower. A poor performance, design or reliability of cooling towers will result in lower flow rate of cooling water an increase in the evaporation of water, an hence losses of water and energy. This paper which presents an experimental investigate of thermal and hydraulic performances of a mechanical cooling tower, enables to show that the water evaporation rate, Mev, increases with an increase in the air and water flow rates, as well as inlet water temperature and for fixed air flow rates, the pressure drop (ΔPw/Z) increases with increasing , L, due to the hydrodynamic behavior of the air/water flow.

Keywords: water, recycle, performance, cooling tower

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Authors: Mustafa A. Al-Refai

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This paper presents the optimal design and simulation of a grid-connected Photovoltaic (PV) system to supply electric power to meet the energy demand by Electrical Department in University of Tripoli Libya. Solar radiation is the key factor determining electricity produced by photovoltaic (PV) systems. This paper is designed to develop a novel method to calculate the solar photovoltaic generation capacity on the basis of Mean Global Solar Radiation data available for Tripoli Libya and finally develop a system design of possible plant capacity for the available roof area. MatLab/Simulink Programming tools and monthly average solar radiation data are used for this design and simulation. The specifications of equipments are provided based on the availability of the components in the market. Simulation results and analyses are presented to validate the proposed system configuration.

Keywords: Photovoltaic (PV), solar energy, solar irradiation, Simulink.

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Authors: Sallama Athab, Hala Bahjat, Zhang Yinghui

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Background detection is essential in video analyses; optimization is often needed in order to achieve real time calculation. Information gathered by dual cameras placed in the front and rear part of an Autonomous Vehicle (AV) is integrated for background detection. In this paper, real time calculation is achieved on the proposed technique by using Priority Regions (PR) and Parallel Processing together where each frame is divided into regions then and each region process is processed in parallel. PR division depends upon driver view limitations. A background detection system is built on the Temporal Difference (TD) and Gaussian Filtering (GF). Temporal Difference and Gaussian Filtering with multi threshold and sigma (weight) value are be based on PR characteristics. The experiment result is prepared on real scene. Comparison of the speed and accuracy with traditional background detection techniques, the effectiveness of PR and parallel processing are also discussed in this paper.

Keywords: Autonomous Vehicle, Background Detection, Dual Camera, Gaussian Filtering, Parallel Processing.

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Authors: Do-Hwan Kim, Roberto Leon

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Probabilistic characteristics of seismic responses of the Partially Restrained connection rotation (PRCR) and panel zone deformation (PZD) installed in older steel moment frames were investigated in accordance with statistical inference in decision-making process. The 4, 6 and 8 story older steel moment frames with clip angle and T-stub connections were designed and analyzed using 2%/50yrs ground motions in four cities of the Mid-America earthquake region. The probability density function and cumulative distribution function of PRCR and PZD were determined by the goodness-of-fit tests based on probabilistic parameters measured from the results of the nonlinear time-history analyses. The obtained probabilistic parameters and distributions can be used to find out what performance level mainly PR connections and panel zones satisfy and how many PR connections and panel zones experience a serious damage under the Mid-America ground motions.

Keywords: Mid-America earthquake, Panel zone, PR connection, Probabilistic characteristics, seismic performance

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Authors: Dinesh M., Kenny Mark V., Dharni Vasudhevan Venkatesan, Santhosh Kumar B., Sree Radesh R., V. R. Sanal Kumar

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Comprehensive numerical studies have been carried out to examine the best aerodynamic performance of subsonic aircraft at different winglet cant angles using a validated 3D k-ω SST model. In the parametric analytical studies NACA series of airfoils are selected. Basic design of the winglet is selected from the literature and flow features of the entire wing including the winglet tip effects have been examined with different cant angles varying from 150 to 600 at different angles of attack up to 140. We have observed, among the cases considered in this study that a case, with 150 cant angle the aerodynamics performance of the subsonic aircraft during takeoff was found better up to an angle of attack of 2.80 and further its performance got diminished at higher angles of attack. Analyses further revealed that increasing the winglet cant angle from 150 to 600 at higher angles of attack could negate the performance deterioration and additionally it could enhance the peak CL/CD on the order of 3.5%. The investigated concept of variable-cant-angle winglets appears to be a promising alternative for improving the aerodynamic efficiency of aircraft.

Keywords: Aerodynamic efficiency, Cant-angle, Drag reduction, Flexible Winglets.

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Authors: M. E. Rahman, D. Sujan, V. Pakrashi, P. Fanning

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The predictability of masonry arch bridges and their behaviour is widely considered doubtful due to the lack of knowledge about the conditions of a given masonry arch bridge. The assessment methods for masonry arch bridges are MEXE, ARCHIE, RING and Frame Analysis Method. The material properties of the masonry and fill material are extremely difficult to determine accurately. Consequently, it is necessary to examine the effect of load dispersal angle through the fill material, the effect of variations in the stiffness of the masonry, the tensile strength of the masonry mortar continuum and the compressive strength of the masonry mortar continuum. It is also important to understand the effect of fill material on load dispersal angle to determine their influence on ratings. In this paper a series of parametric studies, to examine the sensitivity of assessment ratings to the various sets of input data required by the frame analysis method, are carried out.

Keywords: Arch Bridge, Frame Analyses Method, Masonry

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Authors: Gabriela R. Fernandes, Danilo H. Konda, Luiz C. F. Sanches

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In this work, the plate bending formulation of the boundary element method - BEM, based on the Reissner?s hypothesis, is extended to the analysis of plates reinforced by beams taking into account the membrane effects. The formulation is derived by assuming a zoned body where each sub-region defines a beam or a slab and all of them are represented by a chosen reference surface. Equilibrium and compatibility conditions are automatically imposed by the integral equations, which treat this composed structure as a single body. In order to reduce the number of degrees of freedom, the problem values defined on the interfaces are written in terms of their values on the beam axis. Initially are derived separated equations for the bending and stretching problems, but in the final system of equations the two problems are coupled and can not be treated separately. Finally are presented some numerical examples whose analytical results are known to show the accuracy of the proposed model.

Keywords: Boundary elements, Building floor structures, Platebending.

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Authors: Lucie Novakova, Petr Homola, Vaclav Kafka

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Asymmetric incremental sheet forming (AISF) could significantly reduce costs incurred by the fabrication of complex industrial components with a minimal environmental impact. The AISF experiments were carried out on commercially pure titanium (Ti-Gr2), Timetal (15-3-3-3) alloy, and Ti-6Al-4V (Ti-Gr5) alloy. A special testing geometry was used to characterize the titanium alloys properties from the point of view of the forming zone and titanium structure effect. The structure and properties of the materials were assessed by means of metallographic analyses and microhardness measurements.The highest differences in the parameters assessed as a function of the sampling zone were observed in the case of alpha-phase Ti-Gr2at the expense of the most substantial sheet thinning occurrence. A springback causes a smaller stored deformation in Timetal (β alloy) resulting in less pronounced microstructure refinement and microhardness increase. Ti-6Al-4V alloy exhibited early failure due to its poor formability at ambient temperature.

 

Keywords: Incremental forming, metallography, hardness, titanium alloys.

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Authors: Kyoungwoo Park, Byeong Sam Kim, Hyo-Jae Lim, Ji Won Han, Park Kyoun Oh, Juhee Lee, Keun-Yeol Yu

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Predictions of flow and heat transfer characteristics and shape optimization in internally finned circular tubes have been performed on three-dimensional periodically fully developed turbulent flow and thermal fields. For a trapezoidal fin profile, the effects of fin height h, upper fin widths d1, lower fin widths d2, and helix angle of fin ? on transport phenomena are investigated for the condition of fin number of N = 30. The CFD and mathematical optimization technique are coupled in order to optimize the shape of internally finned tube. The optimal solutions of the design variables (i.e., upper and lower fin widths, fin height and helix angle) are numerically obtained by minimizing the pressure loss and maximizing the heat transfer rate, simultaneously, for the limiting conditions of d1 = 0.5~1.5 mm, d2 = 0.5~1.5 mm, h= 0.5~1.5mm, ? = 10~30 degrees. The fully developed flow and thermal fields are predicted using the finite volume method and the optimization is carried out by means of the multi-objective genetic algorithm that is widely used in the constrained nonlinear optimization problem.

Keywords: Computational fluid dynamics, Genetic algorithm, Internally finned tube with helix angle, Optimization.

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Authors: P. Mohajeri Khameneh, I. Mirzaie, N. Pourmahmoud, M. Rahimi, S. Majidyfar

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Three dimensional simulations in tube in tube heat exchangers are investigated numerically in this study. In these simulations forced convective heat transfer and laminar flow of single-phase water are considered. In order to measure heat transfer parameters in these heat exchangers, FLUENT CFD Solver is used in this numerical method. For the purpose of creating geometry and exert boundary and initial conditions in the present model, finite volume method in Computational Fluid Dynamics is used in this study. In the present study, at each Z-location, variation of local temperatures, heat flux and Nusselt number at the whole tube is investigated in detail. Thereafter, averaged computational Nusselt number in this model is calculated. In addition, conceivable pressure drops have been obtained at each Z-location in this model. Then, pressure drop values in the present model are explored. Finally, all the numerical results for this kind of heat exchanger will be discussed precisely.

Keywords: Heat exchanger, Laminar flow, CFD, Nusseltnumber, Tube in tube, pressure drop.

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Authors: H. Nejadriahi

Abstract:

This paper focuses on the performance of Iwan as one of the significant spaces in the traditional architecture of Iran. The aim of this study is to investigate on the role of Iwan in sustainability enhancement of traditional houses of different climatic regions of Iran. Iwan is considered as a semi-open space, which its form and location in the building highly depends to the climatic situation of that region. For that reason, Iwan is recognized as one of the sustainable elements in the traditional houses of Iran, which can provide more comfort with less use of energy. In this study, the history and emergence of Iwan in the traditional architecture of Iran as well as the concept of sustainability in architecture are explained briefly. Then, the change of performance or form of Iwan is analysed in different climatic regions of Iran in accordance to the sustainability concepts. The methods used in this study are descriptive and analytic. Results of this paper verify that studying the sustainability solutions in the traditional architecture of Iran, would be a valuable source of inspiration for the current designers to create an environmental and sustainable architecture for the future.

Keywords: Climatic regions of Iran, Iwan, sustainability, traditional houses.

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Authors: G. Revathi, P. Saikrishnan

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An analysis is performed to study the influence of nonuniform double slot suction on a steady laminar boundary layer flow over a rotating sphere when fluid properties such as viscosity and Prandtl number are inverse linear functions of temperature. Nonsimilar solutions have been obtained from the starting point of the streamwise co-ordinate to the exact point of separation. The difficulties arising at the starting point of the streamwise co-ordinate, at the edges of the slot and at the point of separation have been overcome by applying an implicit finite difference scheme in combination with the quasi-linearization technique and an appropriate selection of the finer step sizes along the stream-wise direction. The present investigation shows that the point of ordinary separation can be delayed by nonuniform double slot suction if the mass transfer rate is increased and also if the slots are positioned further downstream. In addition, the investigation reveals that double slot suction is found to be more effective compared to a single slot suction in delaying ordinary separation. As rotation parameter increase the point of separation moves upstream direction.

Keywords: Boundary layer, suction, mass transfer, rotating sphere.

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Authors: Krishna Mohana Rao, G. Ravi Kumar, P. Sowmya

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This paper presents a study of the Taguchi design application to optimize surface quality in damper inserted end milling operation. Maintaining good surface quality usually involves additional manufacturing cost or loss of productivity. The Taguchi design is an efficient and effective experimental method in which a response variable can be optimized, given various factors, using fewer resources than a factorial design. This Study included spindle speed, feed rate, and depth of cut as control factors, usage of different tools in the same specification, which introduced tool condition and dimensional variability. An orthogonal array of L9(3^4)was used; ANOVA analyses were carried out to identify the significant factors affecting surface roughness, and the optimal cutting combination was determined by seeking the best surface roughness (response) and signal-to-noise ratio. Finally, confirmation tests verified that the Taguchi design was successful in optimizing milling parameters for surface roughness.

Keywords: ANOVA, Damper, End Milling, Optimization, Surface roughness, Taguchi design.

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Authors: S.Ponmalar, S.Sundaravadivelu

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Traditional optical networks are gradually evolving towards intelligent optical networks due to the need for faster bandwidth provisioning, protection and restoration of the network that can be accomplished with devices like optical switch, add drop multiplexer and cross connects. Since dense wavelength multiplexing forms the physical layer for intelligent optical networking, the roll of high speed all optical switch is important. This paper analyzes such an ultra-high speed polymer electro-optic switch. The performances of the 2x2 optical waveguide switch with rectangular, triangular and trapezoidal grating profiles on various device parameters are analyzed. The simulation result shows that trapezoidal grating is the optimized structure which has the coupling length of 81μm and switching voltage of 11V for the operating wavelength of 1550nm. The switching time for this proposed switch is 0.47 picosecond. This makes the proposed switch to be an important element in the intelligent optical network.

Keywords: Intelligent optical network, optical switch, electrooptic effect, coupled mode theory, waveguide grating structures

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Authors: M. Aminu Sanda

Abstract:

This paper explores competencies that managers of small firms in Ghana use to enhance operational flexibility towards the attainment of higher productivity. This is because the requisite competence required of such managers to be effective performers continues to be a challenge. Data was collected from managers of three hundred small firms using a standardized self-completion questionnaire and analyzed using the Amos-based structural equation model approach. Findings from factor and confirmatory factor analyses showed that the only competence exhibited by managers toward effective performance is realistic practices evident at the workplace. It is concluded that a manager’s self-confidence and involvement in areas that he/she is good at, and his/her possession of skills that enables performance at high capacity are indications of the manger’s effectiveness. The study outcome provides a knowledge base helpful to policy-makers, especially in Ghana, in determining the requisite managerial competences required by small firm managers for effective performance.

Keywords: Managerial competence, small firm, effective performance, developing economy, Ghana.

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Authors: Hadi Farhadian, Homayoon Katibeh

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Groundwater inflow to the tunnels is one of the most important problems in tunneling operation. The objective of this study is the investigation of model dimension effects on tunnel inflow assessment in discontinuous rock masses using numerical modeling. In the numerical simulation, the model dimension has an important role in prediction of water inflow rate. When the model dimension is very small, due to low distance to the tunnel border, the model boundary conditions affect the estimated amount of groundwater flow into the tunnel and results show a very high inflow to tunnel. Hence, in this study, the two-dimensional universal distinct element code (UDEC) used and the impact of different model parameters, such as tunnel radius, joint spacing, horizontal and vertical model domain extent has been evaluated. Results show that the model domain extent is a function of the most significant parameters, which are tunnel radius and joint spacing.

Keywords: Water inflow, Tunnel, Discontinues rock, Numerical simulation.

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Authors: M. Hossein Ghadiri, Mohd Farid Mohamed, N. Lukman N. Ibrahim

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Wind catchers are traditional natural ventilation systems attached to buildings in order to ventilate the indoor air. The most common type of wind catcher is four sided one which is capable to catch wind in all directions. CFD simulation is the perfect way to evaluate the wind catcher performance. The accuracy of CFD results is the issue of concern, so sensitivity analyses is crucial to find out the effect of different settings of CFD on results. This paper presents a series of 3D steady RANS simulations for a generic isolated four-sided wind catcher attached to a room subjected to wind direction ranging from 0º to 180º with an interval of 45º. The CFD simulations are validated with detailed wind tunnel experiments. The influence of an extensive range of computational parameters is explored in this paper, including the resolution of the computational grid, the size of the computational domain and the turbulence model. This study found that CFD simulation is a reliable method for wind catcher study, but it is less accurate in prediction of models with non perpendicular wind directions.

Keywords: Wind catcher, CFD, natural ventilation, sensitivity study.

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Authors: I. Markovska, F. Yovkova, G. Minov, D. Rusev, L. Lyubchev

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The present research focus on the processing of mullite-based ceramics from oil refinery industrial wastes and byproducts of agricultural industry and on the investigating of silane modified surface of ceramics. Two waste products were used as initial material – waste aluminum oxide and waste rice husk. The burning - out additives used were waste rise husk. It is known that  the oxide ceramics surface is hydrophilic due to the presence of – OH groups in it. The nature of ceramic surface regarding permeation of water and hydrocarbons can be changed by further treatment with silanes. The samples were studied mainly by X-ray analysis, FT-IR absorbance measurements and microscopic analysis. The X-ray analyses showed the phase composition depends on the firing temperature and on the purity of the starting alumina. Two kind of silanes were used for the transformation of surface from hydrophilic to hydrophobic – trimethoxymethylsilane (TMMS) and trimethylclorsilane (TMCS).

Keywords: Porous mullite ceramics, waste materials, trimethoxymethylsilane, trimethylclorsilane.

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Authors: O. M. Olanrewaju, F. O. Echobu, A. G. Adesoji, E. D. Ajik, J. N. Ndabula, S. Luka

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Nutrients are required for any soil with which plants thrive to improve efficient growth and productivity. Amongst these nutrients required for proper plant productivity are nitrogen, phosphorus and potassium (NPK). Due to factors like leaching, nutrient uptake by plants, soil erosion and evaporation, these elements tend to be in low quantity and the need to replenish them arises. However, this replenishment of soil nutrients cannot be done without a timely soil test to enable farmers to know the amount of each element in short quantity and evaluate the amount required to be added. Though wet soil analysis is good, it comes with a lot of challenges ranging from soil test gargets availability to the technical knowledge of how to conduct such soil tests by the common farmer. The Internet of Things test kit was developed to fill in the gaps created by wet soil analysis, as it can test for NPK, soil temperature and soil moisture in a given soil at the time of test. In this implementation, a sample test was carried out within 0.2 hectares of land divided into smaller plots. The kits performed adequately well, as the range of values obtained across the segments was within a very close range.

Keywords: Internet of things, soil nutrients, test kit, soil temperature.

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Authors: R. Mahjoub, K. Maghsoudi Mehraban

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In recent years, solid oxide fuel cells have been used as one of the main technologies for the production of electrical energy with high-efficiency ratio, which is used hydrogen and other hydrocarbons as fuels. The fuel cell technology can be used either alone or in hybrid gas turbines systems. In this study, thermodynamics analysis for GT-SOFC hybrid system is developed, and then mass balance and exergy equations have been applied not only on the process but also on the individual components of the hybrid system, which enable us to estimate the thermal efficiency of the hybrid systems. Furthermore, various sources of irreversibility in the solid oxide fuel cell system are discussed, and modeling and parametric analyses like heat and pressure are carried out. This study enables us to consider the irreversible effects of solid oxide fuel cells, and also it leads to the specification of efficiency of the system accurately. Next in the study, both methane and hydrogen as a fuel for SOFC are used and implemented, and finally, our results are compared with other references.

Keywords: hybrid system, gas turbine, entropy and exergy analysis, irreversibility analysis

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Authors: Bugao Wang, Weifeng Wang, Xianwei Zeng

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Researches on the general rules of temperature field changing and their effects on the bridge in construction are necessary. This paper investigated the rules of temperature field changing and its effects on bridge using onsite measurement and computational analysis. Guanyinsha Bridge was used as a case study in this research. The temperature field was simulated in analyses. The effects of certain boundary conditions such as sun radiance, wind speed, and model parameters such as heat factor and specific heat on temperature field are investigated. Recommended values for these parameters are proposed. The simulated temperature field matches the measured observations with high accuracy. At the same time, the stresses and deflections of the bridge computed with the simulated temperature field matches measured values too. As a conclusion, the temperature effect analysis of reinforced concrete box girder can be conducted directly based on the reliable weather data of the concerned area.

Keywords: continuous rigid frame bridge, temperature effectanalysis, temperature field, temperature field simulation

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Authors: Laila Zahran Mohammed Alsibani

Abstract:

The aim of the research is to understand the aspects of semiotics in contemporary designs by redesigning an Omani donut brand with localized cultural identity. To do so, visual identity samples of Dice brand of donuts in Oman has been selected to be a case study. This study conducted based on semiotic theory by using mixed method research tools which are: documentation analysis, interview and survey. The literature review concentrates on key areas of semiotics in visual elements used in the brand designs. Also, it spotlights on the categories of semiotics in visual design. In addition, this research explores the visual cues in brand identity. The objectives of the research are to investigate the aspects of semiotics in providing meaning to visual cues and to identify visual cues for each visual element. It is hoped that this study will have the contribution to a better understanding of the different ways of using semiotics in contemporary designs. Moreover, this research can be a reference for further studies in understanding and explaining current and future design trends. Future research can also focus on how brand-related signs are perceived by consumers.

Keywords: Brands, semiotics, visual arts, visual communication.

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