Search results for: Reza Rahnama

Authors: Mohammad Reza Ebrahimi

Abstract:

In new restructured power systems, swift fault detection is very important. The parallel transmission-lines are vastly used in this kind of power systems because of high amount of energy transferring. In this paper, a method based on the comparison of two schemes, i.e., i) maximum magnitude of travelling-wave (TW) energy ii) the instants of maximum energy occurrence at the circuits of parallel transmission-line is proposed. Using the travelling-wave of fault in order to faulted line identification this method has noticeable operation time. Moreover, the algorithm can cover for identification of faults as external or internal faults. For an internal fault, the exact location of the fault can be estimated confidently. A lot of simulations have been done with PSCAD/EMTDC to verify the performance of the proposed algorithm.

Keywords: travelling-wave, maximum energy, parallel transmission-line, fault location

Procedia PDF Downloads 187

Authors: Iman Mazinani, Zubaidah Ismail, Ahmad Mustafa Hashim, Amir Reza Saba

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Two tragic tsunamis that devastated the west coast of Sumatra Island, Indonesia in 2004 and North East Japan in 2011 had damaged bridges to various extents. Tsunamis have resulted in the catastrophic deterioration of infrastructures i.e. coastal structures, utilities and transportation facilities. A bridge structure performs vital roles to enable people to perform activities related to their daily needs and for development. A damaged bridge needs to be repaired expeditiously. In order to understand the effects of tsunami forces on bridges, experimental tests are carried out to measure the characteristics of hydrodynamic force at various wave heights. Coastal bridge models designed at a 1:40 scale are used in a 24.0 m long hydraulic flume with a cross section of 1.5 m by 2.0 m. The horizontal forces and uplift forces in all cases show that forces increase nonlinearly with increasing wave amplitude.

Keywords: tsunami, bridge, horizontal force, uplift force

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Authors: Achmad Buhori, Reza Imam Pratama, Tissa Wiraatmaja, Wanti Megawati

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Data from many countries indicates that there is a marked increase of dental caries. The increases in caries appear to occur in lower socioeconomic groups. It is possible that the benefits of prevention of dental caries are not reaching these groups. However, there is a way to decrease dental caries by adding 5% of bromelain and calcium as an active agent in toothpaste. Bromelain can break glutamine-alanine bond and arginine-alanine bond which is a constituent of amino acid that causes dental plague which is one of the factors of dental caries. Calcium help rebuilds the teeth by strengthening and repairing enamel. Bromelain can be found from the extraction of pineapple (Ananas comosus) cobs (88.86-94.22 % of bromelain recovery during extraction based on the enzyme unit) and calcium can be taken from eggshell (95% of dry eggshell consist of calcium). The aim of this experiment is to make a toothpaste which contains bromelain and calcium as an effective, cheap, and healthy way to decrease dental caries around the world.

Keywords: bromelain, calcium, dental caries, dental plague, toothpaste

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Authors: Mohammad Shams Esfand Abadi, Mohammad Ranjbar, Reza Ebrahimpour

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This work presents the distributed processing solution problem in a diffusion network based on the adapt then combine (ATC) and combine then adapt (CTA)selective partial update normalized least mean squares (SPU-NLMS) algorithms. Also, we extend this approach to dynamic selection affine projection algorithm (DS-APA) and ATC-DS-APA and CTA-DS-APA are established. The purpose of ATC-SPU-NLMS and CTA-SPU-NLMS algorithm is to reduce the computational complexity by updating the selected blocks of weight coefficients at every iteration. In CTA-DS-APA and ATC-DS-APA, the number of the input vectors is selected dynamically. Diffusion cooperation strategies have been shown to provide good performance based on these algorithms. The good performance of introduced algorithm is illustrated with various experimental results.

Keywords: selective partial update, affine projection, dynamic selection, diffusion, adaptive distributed networks

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Authors: Kasra HosseinMostofi, Mohamadamin Oyar Hossein, Reza Mehdizadeh Anvigh

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BIM is an innovative concept for the majority of firms operating in industry. BIM offers a new paradigm to design, construct, operate, and maintain a facility. However, even with the most conscientious use, stakeholders can run into trouble during its implementation on a project or within an organization. At times, project stakeholders are unaware of the challenges that they can face with the implementation at the project level or an organizational level. Therefore, the study aimed to identify and compile barriers associated with the BIM implementation at the project and organizational level, as per the literature. Despite the fact that innumerable advantageous involved in exploiting BIM, there are some barriers to implement it properly. These barriers have been proved as impediments for academicians and members of construction team project to take the maximum advantage of its utilization. Although some research has been conducted to identify these barriers regarding BIM implementation in construction industry, more research is needed to be carried out among academicians to identify these barriers in institutions, and most importantly, to make suggestions for eliminating these obstacles.

Keywords: building information modelling, construction, design and construction, designers

Procedia PDF Downloads 185

Authors: Mojtaba Aghamiri Esfahani, Mohammad Karkon, Seyed Majid Hosseini Nezhad, Reza Hosseini-Ara

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In this study, the effect of uncertainty in elastic modulus of a plate on free vibration response is investigated. For this purpose, the elastic modulus of the plate is modeled as stochastic variable with normal distribution. Moreover, the distance autocorrelation function is used for stochastic field. Then, by applying the finite element method and Monte Carlo simulation, stochastic finite element relations are extracted. Finally, with a numerical test, the effect of uncertainty in the elastic modulus on free vibration response of a plate is studied. The results show that the effect of uncertainty in elastic modulus of the plate cannot play an important role on the free vibration response.

Keywords: stochastic finite elements, plate bending, free vibration, Monte Carlo, Neumann expansion method.

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Authors: Ansari Mohammad Reza, Hiroko Ono

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In this study, we investigated how much of the urban facilities are fairly distributing in the city of Kabul based on the factor of population. To find the answer to this question we simulated a fair model for the distribution of investigated facilities in the city which is proposed based on the consideration of two factors; the number of users for each facility and the average distance of reach of each facility. Then the model was evaluated to make sure about its efficiency. And finally, the two—the existing pattern and the simulation model—were compared to find the degree of bias in the existing pattern of distribution of facilities in the city. The result of the study clearly clarified that the facilities are not fairly distributed in Kabul city based on the factor of population. Our analysis also revealed that the education services and the parks are the most and the worst fair distributed facilities in this regard.

Keywords: Afghanistan, ArcGIS Software, Kabul City, fair distribution, urban facilities

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Authors: Reza Vakili

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To assess the effect of different levels of soybean oil (SO: 1, 2%) and different types of pellet binders (sodium bentonite (SB), calcium lignosulfonate (Ca-Ls), and plant compounds (PC) on the pellet quality, and broilers’ performance, 480 one-day-old male broiler chickens (Ross 308) were used. The results showed that in the starter diet, the 1-PC group had the highest pellet durability index (PDI) (P<0.05). The PDI of the grower diet containing SB and PC was higher than others (P<0.05). The highest pellet hardness was observed in groups 1-SB, 1-PC, 2-SB, and 2-PC for the starter diet (P<0.05). For the finisher diet, the hardness of pellets containing SB and PC was higher (P<0.05). During the starter phase, the best feed conversion ratio (FCR) was obtained in 1-SB (P<0.05). The lowest and highest daily feed intake was observed in groups 2-PC and 1-SB, respectively, during the finisher phase. During the finisher and whole phases, the most daily body weight gain was observed in the SB group (P<0.05).

Keywords: bentonite, birds, body weight, feed processing, pellet durability, soybean oil

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Authors: Javad Hesari, Tahereh Donyatalab, Sodeif Azadmard Damirchi, Reza Rezaii Mokaram, Abbas Rafat

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The main objective of this research was to increase shelf life of stirred yoghurt by adding chitosan as a naturally antimicrobial compound. Chitosan were added at different concentrations (0.1, 0.3 and 0.6%) to the stirred yoghurt. Samples were stored at refrigerator and room temperature for 3 weeks and tested with respect of microbial properties (counts of starter bacteria, mold and yeast, coliforms and E. coli). Starter bacteria and yeast counts in samples containing chitosan was significantly (p<0.05) lower than those in control samples and its antibacterial and anti-yeast effects increased with increasing concentration of chitosan. The lowest counts of starter bacteria and yeast were observed at samples whit 0.6% of chitosan. The Results showed Chitosan had a positive effect on increasing shelf life and controlling of yeasts and therefore can be used as a natural preservative in stirred yogurt.

Keywords: chitosan, natural preservative, stirred yoghurt, self-life

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Authors: K. M. Salim Reza, M. Hafiz Mia, M. A. Aziz, M. A. Motin, M. M. Rahman, M. A. Hasem

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The redox behavior of Fe (III) in presence of Catechol (Cc) has been carried out in buffer solution of different pH, scan rate, variation of Fe (III) concentration and Cc concentration. Uncoordinated Fe(III) or Cc has been found to undergo reversible electrode reaction whereas coordinated Fe-Cc is irreversible. The peak positions of the voltammogram of Fe- Cc shifted with respect to that of free Fe (III) or Cc and also developed a new peak at 0.12 V. The peak current of Fe-Cc decreases significantly compared with that of free Fe(III) or Cc in the same experimental conditions. These behaviors ascribed the formation of complex of Fe with Cc. The complex was formed either by the addition of Cc into Fe(III) or by the addition of Fe(III) into Cc. The effect of pH of Fe-Cc complex was studied by varying pH from 2 to 8.5. The electro chemical oxidation of Fe-Cc is facilitated in lower pH media. The slope of the plots of anodic peak current, Ep against pH of Fe-Cc complexe is 30 mV, indicates that the oxidation of Fe-Cc complexes proceeded via the 2e−/2H+ processes. The proportionality of the anodic and cathodic peak currents with square root of scan rate of suggests that the peak current of the different complexes at each redox reaction is controlled by diffusion process.

Keywords: cyclic voltammetry, Fe-Cc Complex, pH effect, redox interaction

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Authors: Abbas Moradi, Mohsen Safajoy, Reza Yazdanparast

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Analysis of blade-disc dovetail joints is one of the biggest challenges facing designers of aero-engines. To avoid comparatively expensive experimental full-scale tests, numerical methods can be used to simulate loaded disc-blades assembly. Mortar method provides a powerful and flexible tool for solving frictional contact problems. In this study, 2D frictional contact in dovetail has been analysed based on the mortar algorithm. In order to model the friction, the classical law of coulomb and moving friction cone algorithm is applied. The solution is then obtained by solving the resulting set of non-linear equations using an efficient numerical algorithm based on Newton–Raphson Method. The numerical results show that this approach has better convergence rate and accuracy than other proposed numerical methods.

Keywords: computational contact mechanics, dovetail joints, nonlinear FEM, mortar approach

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Authors: Zahra Mirsanjari, Mohammad Reza Baradaran, Mehdi Rastegari Ghiri

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Research in the field of education has widely documented that teachers’ sense of efficacy has strong impacts on various aspects of teaching and learning. The present study is an attempt to examine Iranian EFL teachers’ degree of self-efficacy for teaching English. The data required for the study was gathered from Iranian EFL teachers teaching English as a foreign language in different schools and language institutes in Iran. Data were collected using Teacher’s Sense of Efficacy Scale (TSES). Results identified four dimensions of teachers’ English teaching-specific sense of efficacy: instructional strategies, classroom management, student engagement, and oral English language use. It was also found that teachers rated their self-efficacy in teaching English at a moderate level in the dimensions of instructional strategies, classroom management, and student engagement. Results have implications for language teachers and practitioners.

Keywords: Self-efficacy, teaching, EFL, teachers

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Authors: Reza Samsami

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The aim of the study was to degradation of polycyclic aromatic hydrocarbons (PAHs) by proxy-acid method. The amounts of PAHs were determined in a silty-clay soil sample of an aged oil refinery field in Abadan, Iran. Proxy-acid treatment method was investigated. The results have shown that the proxy-acid system is an effective method for degradation of PAHs. The results also demonstrated that the number of fused aromatic rings have not significant effects on PAH removal by proxy-acid method. The results also demonstrated that the number of fused aromatic rings have not significant effects on PAH removal by proxy-acid method.

Keywords: proxy-acid treatment, silty-clay soil, PAHs, degradation

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Authors: Reza M. Rudd, Ali Saeedi, Colin Wood

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In this article, the latest advancements made in the applications of polymers in the enhanced hydrocarbon recovery technologies are investigated. For this purpose, different classes of polymers are reviewed and the latest progresses made in making them suitable for application under harsh reservoir conditions are discussed. The main reservoir conditions whose effects are taken into account include the temperature, rock mineralogy and brine salinity and composition. For profile modification and blocking the thief zones, polymers are used in the form of nanocomposite hydrogels. Polymers are also used as thickeners during CO2 flooding. Also, they are used in enhanced gas recovery, to inhibit the mixing of injection gas with the in-situ natural gas. This review covers the main types of polymers, their functions and the challenges in their applications, some of which are mentioned above. Included in this review are also the latest progresses made in the development of new polymeric surfactants used for surfactant flooding.

Keywords: EOR, EGR, polymer flooding, profile modification, mobility control, nanocomposite hydrogels, CO2 flooding, polymeric surfactants

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Authors: Ebrahim Ghanbari, Mohammad Reza Nematollahi

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Integrating deterministic and probabilistic safety assessment (IDPSA) is one of the most commonly used issues in the field of safety analysis of power plant accident. It has also been recognized today that the role of human error in creating these accidents is not less than systemic errors, so the human interference and system errors in fault and event sequences are necessary. The integration of these analytical topics will be reflected in the frequency of core damage and also the study of the use of water resources in an accident such as the loss of all electrical power of the plant. In this regard, the SBO accident was simulated for the pressurized water reactor in the deterministic analysis issue, and by analyzing the operator's behavior in controlling the accident, the results of the combination of deterministic and probabilistic assessment were identified. The results showed that the best performance of the plant operator would reduce the risk of an accident by 10%, as well as a decrease of 6.82 liters/second of the water sources of the plant.

Keywords: IDPSA, human error, SBO, risk

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Authors: Mohammad Reza Fooladi

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Because of the importance and effect of plant innovations on economy, industry, and especially agriculture, they have been on the core attention of legislators at the national level, and have been a topic of international documents related to intellectual innovations in the recent decades. For protection of plant innovations, two legal systems (i.e. particular system based on International Convention for protection of new variety of plants, and the patent system) have been considered. Ease of access to the support and the level of support in each of these systems are different. Our attempt in this paper, in addition to describing and analyzing the characteristics of each system, is to suggest the compatible system to the industry and agriculture of Afghanistan. Due to the lack of sufficient industrial infrastructure and academic research, the particular system based on the International Convention on the protection of new variety of plants is suggested. At the same time, appropriate industrial and legal infrastructures, as well as laboratories and research centers should be provided in order that plant innovations under the patent system could also be supported.

Keywords: new varieties of plant, patent, agriculture, Afghanistan

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Authors: Reza Reiazi

Abstract:

Attempts to verify Geant4 hadronic physic to transport antiproton beam using standard physics list have not reach to a reasonable results because of lack of reliable cross section data or non reliable model to predict the final states of annihilated particles. Since most of the antiproton annihilation energy is carried away by recoiling nuclear fragments which are result of pions interactions with surrounding nucleons, it should be investigated if the toolkit verified for pions. Geant4 version 9.4.6.p01 was used. Dose calculation was done using 700 MeV pions hitting a water tank applying standards physic lists. We conclude Geant4 standard physics lists to predict the depth dose of Pion minus beam is not same for all investigated models. Since the nuclear fragments will deposit their energy in a small distance, they are the most important source of dose deposition in the annihilation vertex of antiproton beams.

Keywords: Monte Carlo, Pion, simulation, antiproton beam

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Authors: Morteza Habibi, Reza Amrollahi

Abstract:

The Aluminum made targets were placed at the central part of a Fillipov type (90KJ) plasma focus cathode. These targets were exposed to perpendicular dense plasma stream incidence. Melt layer erosion by melt motion, surface smoothing, and bubble formation were some of different effects caused by diverse working conditions. Micro hardness of surface layer tends to decrease particularly in the central region of the sample where destruction is more intense. The most pronouced melt motion is registered in the region of the maximum gradient of pressure and the etching of aluminium surface is noticeable in the central part of target. The crater with a maximum depth of 200µm, and the diameter of about 8.5mm is observed close to the mountains. Adding Krypton admixture to the Deuterium gas lead to collapsing bubbles and greater surface damage.

Keywords: fillipov type plasma focus, al target interaction, bubbling effect, melt layer motion, surface smoothing

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Authors: Tahereh Talebi, Reza Ghomashchi, Pejman Talemi, Sima Aminorroaya

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A high quality crack-free film of Bi₂Te₃ material has been deposited for the first time using electrophoretic deposition (EPD) and microstructures of various films have been investigated. One of the most important thermoelectric (TE) applications is Bi₂Te₃ to manufacture TE generators (TEG) which can convert waste heat into electricity targeting the global warming issue. However, the high cost of the manufacturing process of TEGs keeps them expensive and out of reach for commercialization. Therefore, utilizing EPD as a simple and cost-effective method will open new opportunities for TEG’s commercialization. This method has been recently used for advanced materials such as microelectronics and has attracted a lot of attention from both scientists and industry. In this study, the effect of media of suspensions has been investigated on the quality of the deposited films as well as their microstructure. In summary, finding an appropriate suspension is a critical step for a successful EPD process and has an important effect on both the film’s quality and its future properties.

Keywords: Bi2Te3, electrical conductivity, electrophoretic deposition, thermoelectric materials, thick films

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Authors: Soroush Rasti Boroujeni, S. Hassan Mousavi, Javad Ebrahimizadeh, Ardeshir Palizban, Mohammad-Reza Nezhad-Ahmadi, Safieddin Safavi-Naeini

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This paper presents a wideband True Time Delay (TTD) phase shifter with low insertion loss variation. The circuit benefits from a controllable resistive load shunt with transmission line segments to optimize return loss variations, addressing the unbalanced capacitive nature of the varactor. The phase shifter reduces the complexity of the calibration process because the dependency of insertion loss on voltage controls is improved up to 3 dB. The TTD phase shifter provides a continuous changing delay time of 6.4 ps with low insertion loss (IL) in the 10-35 GHz frequency range. The proposed circuit benefits from lowloss phase shifters with a small footprint. Fabricated using a 65 nm CMOC process, the TTD phase shifter occupies only 388 × 615 μm² of chip area, achieving a 20% improvements compared to conventional TTD phase shifters.

Keywords: millimeter-wave phased-array, true time delay phase shifter, insertion loss variation, compact size

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Authors: Mohammad Reza Abidi, Zahra Nourouz Pour, Mehdi Moudi

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In this research, firstly critical success factors and deterrent factors in implementing projects and also the factors those cause information technology productivity (IT) paradox in Islamic Azad University, Zahedan branch examined. Research method of this paper is descriptive. In fact, the researcher by using survey, proposed useful solutions. In this research, subjects’ responders to questionnaires items were based on Likert scale. In the questionnaire, economic, technical, organizational and cultural factors in the university have been assessed in order to obtain the necessary validity. We used masters and technicians of IT department’s advices to realize reliability and consistency. For the reliability test we used Cronbach’s reliability test and validity has been obtained using SPSS software. Because of the research questions and objectives, t-student test is used for hypothesis testing. Finally we analyze the findings, we offer conclusions and suggestions.

Keywords: IT projects, Islamic Azad University, success factors, deterrent factors

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Authors: Reza Dehghani Bidgoli

Abstract:

Although Artemisia species are one of the most important medicinal plants, there are a few reports on chemistry or activity of their essential oils because of low amounts of the oils in this genus. In this study, chemical composition of essential oils leaves and stems of Artemisia sieberi and Artemisia aucheri growing wild in Kashan rangelands, central Iran, have been analyzed using GC–MS technique. Analysis revealed 50 identified compounds, representing 96.55% of the oil and 23 identified compounds representing 97.83% of the oil on Artemisia sieberi and Artemisia aucheri respectively. The yield of essential oil extraction is very higher than those of previous reports. In both plants α-thujene is the main component in both of them, with an extra value, 74.42%, in aucheri species. Several compounds (some with significant compositions), were found in these varieties of Artemisia which are not recorded in previous literature. Antioxidant activities of the essential oils were evaluated for the first time in this research work using β-carotene/linoleic acid assay and found to be surprisingly attributed directly to α-pinene contents in them.

Keywords: essential oil, artemisia aucheri, artemisia sieberi, α-thujene, antioxidant activity

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Authors: Reza Eslami-Farsani, Hamed Khosravi

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The aim of this work is to study the influence of multi-walled carbon nanotubes (MWCNTs) addition at various contents with respect to the matrix (0-0.5 wt.% at a step of 0.1 wt.%) on the compressive response of unidirectional basalt fiber (UD-BF)/epoxy composites. Toward this end, MWCNTs were firstly functionalized with 3-glycidoxypropyltrimethoxysilane (3-GPTMS) to improve their dispersion state and interfacial compatibility with the epoxy. Subsequently, UD-BF/epoxy and multiscale 3-GPTMS-MWCNTs/UD-BF/epoxy composites were prepared. The mechanical properties of the composites were determined by quasi-static compression test. The compressive strength of the composites was obtained through performing the compression test on the off-axis specimens and extracting their longitudinal compressive strength. Results demonstrated that the highest value in compressive strength was attained at 0.4 wt.% MWCNTs with 41% increase, compared to the BF/epoxy composite. Potential mechanisms behind these were implied.

Keywords: multiscale polymeric composites, unidirectional basalt fibers, multi-walled carbon nanotubes, surface modification, compressive properties

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Authors: Hana Almakky, Reza Sahandi, Jacqui Taylor

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Social media continue to grow, and user interfaces may become more appealing if cultural characteristics are incorporated into their design. Facebook was designed in the west, and the original language was English. Subsequently, the words in the user interface were translated to other languages, including Arabic. Arabic words are written from right to left, and English is written from left to right. The translated version may misrepresent the original design and users preferences may influence their culture, which should be considered in the user interface design. Previous research indicates that users are more comfortable when interacting with a user interface, which relates to their own culture. Therefore, this paper, using a survey investigates the preferences of Saudi Arabian on the Arabic version of user interface of Facebook.

Keywords: culture, social media, user interface design, Facebook, Saudi Arabia

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Authors: Azar Alizadeh, Mohammad Reza Naserkhaki

Abstract:

The application of the IT systems for collecting and analyzing the data can have a significant effect on the performance of any company. In recent decade, different advancements and achievements in the field of information technology have changed the industry compared to the previous decade. The adoption and application of the information technology are one of the ways to achieve a distinctive competitive personality to the companies and their supply chain. The acceptance of the IT and its proper implementation cam reinforce and improve the cooperation between different parts of the supply chain by rapid transfer and distribution of the precise information and the application of the informational systems, leading to the increase in the supply chain efficiency. The main objective of this research is to study the effects and applications of the information technology on and in the supply chain management and to introduce the effective factors on the acceptance of information technology in the companies. Moreover, in order to understand the subject, we will investigate the role and importance of the information and electronic commerce in the supply chain and the characteristics of the supply chain based on the information flow approach.

Keywords: electronic commerce, industry, information technology, management, supply chain, system

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Authors: Reza Ziaie Moayed, Naeem Gholampoor

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Jet grouting strengthened pile (JPP) is one of composite piles used in soft ground improvement. It may improve the vertical and lateral bearing capacity effectively and it has been practically used in a considerable scale. In order to make a further research on load transfer mechanism of single JPP with and without cap under lateral loads, JPP is analyzed by means of FEM analysis. It is resulted that the JPP pile could improve lateral bearing capacity by compared with bored concrete pile which is higher for shorter pile and the biggest bending moment of JPP pile is located in the depth of around 48% of embedded length of the pile. Meanwhile, increase of JPP pile length causes to increase of peak mobilized bending moment. Also, by cap addition, JPP piles will have a much higher lateral bearing capacity and increasing in cohesion of soil layer resulted to increase of lateral bearing capacity of JPP pile. In addition, the numerical results basically coincide with the experimental results presented by other researchers.

Keywords: bending moment, FEM analysis, JPP pile, lateral bearing capacity

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Authors: Mohammad Reza Taherkhani‎

Abstract:

Wireless sensor networks that are used to monitor a special environment, are formed from a large number of sensor nodes. The role of these sensors is to sense special parameters from ambient and to make a connection. In these networks, the most important challenge is the management of energy usage. Clustering is one of the methods that are broadly used to face this challenge. In this paper, a distributed clustering protocol based on learning automata is proposed for underwater wireless sensor networks. The proposed algorithm that is called LA-Clustering forms clusters in the same energy level, based on the energy level of nodes and the connection radius regardless of size and the structure of sensor network. The proposed approach is simulated and is compared with some other protocols with considering some metrics such as network lifetime, number of alive nodes, and number of transmitted data. The simulation results demonstrate the efficiency of the proposed approach.

Keywords: underwater sensor networks, clustering, learning automata, energy consumption

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Authors: Hamed Abshari, M. Reza Emami Azadi, Madjid Sadegh Azar

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For studying the overall instability of members of steel structures, there are several methods in which overall buckling and geometrical imperfection effects are considered in analysis. In first section, these methods are compared and ability of software to apply these methods is studied. Buckling loads determined from theoretical methods and software is compared for 2D one bay, one and two stories steel frames. To consider actual condition, buckling loads of three steel frames that have various dimensions are calculated and compared. Also, uncertainties that exist in loading and modeling of structures such as geometrical imperfection, yield stress, and modulus of elasticity in buckling load of 2D framed steel structures have been studied. By performing these uncertainties to each reliability analysis procedures (first-order, second-order, and simulation methods of reliability), one index of reliability from each procedure is determined. These values are studied and compared.

Keywords: buckling, second-order theory, reliability index, steel columns

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Authors: Badiossadat Hassanpour, Reza Sirjani, Nangkuala Utaberta

Abstract:

The avant-garde educational systems are striving to find a life long learning methods. Different fields and majors have test variety of proposed models, and found their difficulties and strengths. Architecture as a critical stage of education due to its characteristics which are learning by doing and critique based education and evaluation is out of this study procedure. Learning contracts is a new alternative form of evaluation of students’ achievements, while it acts as agreement about learning goals. Obtained results from studies in different fields which confirm its positive impact on students' learning in those fields and positively affected students' motivation and confidence in meeting their own learning needs, prompted us to implement this model in architecture design studio. In this implemented contract to the studio, students were asked to use the existing possibility of contract to have self assessment and examine their professional development to identify whether they are deficient or they would like to develop more expertise. The evidences of this research as well indicate that students feel positive about the learning contract and see it accommodating their individual learning needs.

Keywords: contract (LC), architecture design studio, education, student-centered learning

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Authors: Alireza Toloei, Ahmad R. Saffary, Reza Ghasemi

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Due to the growing need for energy and limited fossil resources, the use of renewable energy, particularly wind is strongly favored. We all wind energy can’t be saved. Betz law, 59% of the total kinetic energy of the wind turbine is extracting. Therefore turbine control to achieve maximum performance and maintain stable conditions seem necessary. In this article, we plan for a horizontal axis wind turbine variable-speed variable-pitch nonlinear controller to obtain maximum output power. The model presented in this article, including a wide range of wind turbines are horizontal axis. However, the parameters used in this model is from Vestas V29 225 kW wind turbine. We designed second order sliding mode controller, which was robust in the face of changes in wind speed and it eliminated chattering by using of super twisting algorithm. Finally, using MATLAB software to simulate the results we considered the accuracy of the simulation results.

Keywords: non linear controller, robust, sliding mode, kinetic energy

Procedia PDF Downloads 501