فهرست مطالب

  • Volume:30 Issue: 4, 2017
  • TRANSACTIONS A: Basics
  • تاریخ انتشار: 1396/02/09
  • تعداد عناوین: 22
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  • P. Ebrahimnejad, M. Khavarpour*, S. Khalili Pages 456-463
    Chitosan was used for nanoencapsulation of Lactobacillus acidophilus as probiotic bacteria. In vitro experiments were conducted with the objective of investigating the survival of the bacterial cells in gastro-intestinal conditions. The results demonstrated that the size of chitosan nanoparticles noticeably increased by increasing chitosan concentration from 0.05 to 0.5 g/mL. Encapsulation of the cells caused a decrease at the leakage of probiotic bacteria when compared to free bacteria. However, the number of probiotic cells reduced from 3.27 to 3.23 log CFU/mL in gestural acid condition in contrast to free cells which they approximately dropped from 3.3 to 3 log CFU/mL after 120 min. Good probiotic viability and stability was also obtained by nanocapsulation of Lactobacillus acidophilus in intestinal juice. At this condition, the initial capsulated cells numbers were 3.28 log CFU/mL which after placing in biliary salt condition for 120 min, it reached to 3.23 log CFU/mL. On the other hand, the free bacteria cells reduced from 3.3 to 2.97 log CFU/mL in intestinal environment.
    Overall, nanocapsulation of probiotic bacteria plays a pivotal role in enhancing the viability and survival of them against gastro- intestinal environmental conditions.
    Keywords: Probiotic Bacteria, Lactobacillus acidophilus, Nanocapsulation, Chitosan, Gastro-intestinal Condition
  • K. Azizi, M. Keshavarz Moraveji* Pages 464-472
    A two fluid model (TFM) was used to study gas-solid heat transfer in a riser with different inclination angles. A two dimensional pipe with 5.8 cm internal diameter and 5 meter length was chosen. Effect of bed angle and solid particles feed rate were studied on the heat transfer behavior of gas and solid particles. Obtained results from simulation are compared with the experimental data in the relevant literature. Heat transfer behavior of phases is different in an inclined pipe in comparison with vertical and horizontal pipes. It is found that higher air-solid Nusselt number, air temperature difference and particle temperature difference take place at the pipe with inclination angle equal to 45 degrees. Loading ratio enhancement increases gas temperature differences. At lower and higher loading ratio, particles temperature differences decreases and increases respectively with loading ratio enhancement.
    Keywords: Fluidized Bed, Computational Fluid Dynamic Simulation, Heat Transfer, Inclination Angle
  • G. Thrinath*, P. Sundara Kuma Pages 473-478
    Today concrete is most generally utilized development material in the world due to its strength and sturdiness properties. To attain good strength, curing of concrete is important so we introduce the concept of self-curing concrete rather than immersion or sprinkle curing to avoid water scarcity. It was observed that water solvent polymers can be utilized as a self-curing agent, i.e. polyethylene glycol (PEG-400). In the present study, to discover the effect of admixture polyethylene glycol (PEG-400) on compression strength, split tensile strength and flexural strength, adding the diverse rate of PEG-400 to the weight of cement from zero to two percentages as the measurement of the curing agent is done. The test results were studied for M30 concrete mix. The optimum percentage of PEG-400 was found to be 1% for compressive and Split Tensile Strength. If the dosage of PEG-400 increases to more than 1%, there is a decline in compressive and split tensile strength. However, the optimum percentage of PEG-400 for flexural strength was found at 0.5%. If we increase the dosage of PEG-400 more than 0.5%, there is reduction in strength of flexural strength.
    Keywords: Self-curing Concrete, Immersion Curing, Polyethylene Glycol 400, Compressive Strength, Split Tensile Strength, Flexural Strength
  • D. K. Verma*, B. Setia, V. K. Arora Pages 479-485
    Failure of dams due to overtopping is among the most frequent forms of embankment failures. Owing to massive and wide spread damage to structures and loss of lives associated with a dam failure, the subject has drawn the attention of scientists. The study also becomes essential for damage assessment and for development of early warning system of people downstream of the embankment. The rate of breaching of earthen embankments due to overtopping depends upon the soil and flow characteristics alike. Different input parameters that help in understanding the phenomenon are the temporal variation of initiation of the breach, breach width, breach depth, intensity of discharge and its time-to-peak. Present paper gives the results of laboratory investigation conducted using a wooden fuse plug and five different soils. The hydraulic conditions were kept same for all the experiments. It was observed that cohesiveness and degree of compaction were key factors in the erosion process. While for pure non-cohesive soils, surface erosion occurred gradually, but for the cohesive soils, headcut erosion was observed. The behaviour of breach depends upon dimensions of fuse plug, type of fill material, reservoir capacity and inflow. A common equation has been fitted to the series of normalized breach flow hydrographs of different soils. The equation has a coefficient of correlation R2 equal to 0.8 indicating a good fit. Limited space of storage reservoir on the upstream of the embankment, and width of the flume are the limitations of the study.
    Keywords: Fuse Plug, Breach Flow, Hydrograph, Scaled Parameters
  • S. Rao Chintalapudi*, M. H. M. Krishna Prasad Pages 486-492
    Detecting communities plays a vital role in studying group level patterns of a social network and it can be helpful in developing several recommendation systems such as movie recommendation, book recommendation, friend recommendation and so on. Most of the community detection algorithms can detect disjoint communities only, but in the real time scenario, a node can be a memberof more than one community at the same time, that leads to overlapping communities. A novel approach is proposed to detect such overlapping communities by extending the definition of newman’s modularity for overlapping communities. The proposed algorithm is tested on LFR benchmark networks with overlapping communities and on real-world networks. The performance of the algorithm is evaluated using popular metrics such as ONMI, Omega Index, F-score and Overlap modularity and the results are compared with its competent algorithms. It is observed that extended modularity gain can detect highly modular structures in complex networks with overlapping communities.
    Keywords: Social Network Analysis, Community Detection, Overlapping Communities, Graph Mining, Modularity, Extended Modularity Gain
  • H. Kashanian, E. Dabaghi* Pages 493-499
    These days, the most important areas of research in many different applications, with different tools, are focused on how to get awareness. One of the serious applications is the awareness of the behavior and activities of patients. The importance is due to the need of ubiquitous medical care for individuals. That the doctor knows the patient's physical condition, sometimes is very important. Of course, there are other important applications for this information. There are a variety of methods and tools for measurement, gathering, and analysis of the physical behaviors and activities’ information. One of the most successful tools for this aim are ubiquitous intelligent electronic devices, specifically smartphones, and smart watches. There are many sensors in these devices, some of which can be used to understand the activities of daily living. As an output result, these sensors produce many raw data. Thus, it is needed to process these information and recognize the individual behavior of the output of this processing. In this paper, the basic components of the analysis phase for this process have been proposed. Simulations validate the benefits and superiority of this method.
    Keywords: Principle Components Fuzzy Analysis, Multisensor Data Fusion, Ubiquitous Activities Monitoring, Intelligent Devices, Health Care
  • A. Siadatan*, S. Ghasemi, S. S. Shamsabad Farahani Pages 500-506
    In this paper the method of sensorless startup of direct current brushless motor using third harmonic back Electromotive Force (EMF) and motor startup using microcontroller for pulse width modulation, power switch control and motor output analysis is presented which renders RPM control and high speed achievement for motor. The microcontroller is used for processor and metal-oxide semiconductor field-effect transistor (MOSFETs) are used for power circuit. Besides, the motor does not have any sensors to detect rotor position. Furthermore, the microcontroller modulates pulse width, controls power circuit and analyses motor output. The innovation in this research is that the third harmonic function is used for motor control and is compared with the Back-EMF force to recognize zero crossing. Moreover, N-type MOSFETs are used in power circuit high side and low side which are useful in the current rate of MOSFETs due to their similarities. Also, the IR2101 MOSFET drive is utilized for startup which improves the firing time of MOSFETs. Besides, using tantalum capacitors and putting resistor by the gate route of MOSFETs is efficient. Finally, experimental results are given to verify the validation of the proposed method.
    Keywords: Brushless DC Motor, Pulse Width Modulation, Third Harmonic Back Electromotive Force, Zero Crossing
  • M. Sadeghijaleh*, M. M. Fateh Pages 507-515
    Tracking control of the direct-drive robot manipulators in high-speed is a challenging problem. The Coriolis and centrifugal torques become dominant in the high-speed motion control. The dynamical model of the robotic system including the robot manipulator and actuators is highly nonlinear, heavily coupled, uncertain and computationally extensive in non-companion form. In order to overcome these problems, this paper presents a novel adaptive control for direct-drive robot manipulators driven by Permanent Magnet Synchronous Motors (PMSM) in tracking applications. The novelty of this paper is that the proposed adaptive law is free from manipulator dynamics by using the Voltage Control Strategy (VCS). Additionally, a state space model of the robotic system driven by PMSM is presented. The VCS differs from the commonly used control strategy for robot manipulators the so called torque control strategy. The position control of the PMSM is effectively used for the tracking control of the robot manipulator. This idea takes the control problem from the manipulator control to the motor control resulting in a simple yet efficient control design. Compared with the torque control, the control design is simpler, easier to implement with better tracking performance. The control method is verified by stability analysis. Simulation results show superiority of the proposed control to the torque control applied by field oriented control on the direct-drive robot driven by PMSM.
    Keywords: Direct-drive Robot, Adaptive Control, Permanent Magnet Synchronous Motor, Voltage Control Strategy, Field Oriented Control
  • G. R. Karimi*, S. G. Shirazi Pages 516-522
    Due to emergence of serious obstacles by scaling of the transistors dimensions, it has been obviously proved that silicon technology should be replaced by a new one having a high ability to overcome the barriers of scaling to nanometer regime. Among various candidates, carbon nanotube (CNT) field effect transistors are introduced as the most promising devices for substituting the silicon-based technologies. Since the channel of these transistors is made of CNT then its properties, such as chiral vector, have prominent effects on determining the performance of devices. In this paper the CNT diameter impact on tunneling and thermionic emission (TE) currents of a coaxially-gated carbon nanotube field effect transistor (CNTFET) with doped source/drain extensions is investigated. The source/channel/drain of this transistor are a zigzag CNT with (n,0) chirality. The “n” value could be in the form of n = 3a 1 or n = 3a 2. By increasing the “a”, the diameter increases while the energy band gap EG of the CNT decreases; as a result by increasing the “a” value, the on/off current ratio decreases. However, for n = 3a 2 the EG of a CNT shows a higher value; then at a given “a”, for n = 3a 1 the on/off current ratio may decrease due to a lower EG and hence higher tunneling and TE current. Generally, subthreshold swing improves and threshold voltage increases for a lower diameter device; consequently, the leakage current could diminish. ON-state current and output conductance have higher values for a higher diameter. Also, the difference between EG and hence the I-V characteristics of the device with n = 3a and n = 3a 2 is negligible for a higher diameter value. All the results could be justified based on the energy-position resolved electron density and current spectrums on energy band diagram of the device.
    Keywords: Carbon Nanotube, Voltage Effect Transistor, Channel Diameter, Device Performance, Quantum Simulation
  • M. Esmaili, R. Sahraeian* Pages 523-531
    In multi-echelon distribution strategy freight is delivered to customers via intermediate depots. Rather than using direct shipments, this strategy is an increasingly popular one in urban logistics. This is primarily to alleviate the environmental (e.g., energy usage and congestion) and social (e.g., trafficrelated air pollution, accidents and noise) consequences of logistics operations. This paper represents a two-echelon capacitated vehicle routing problem (2-ECVRP) in which customer's satisfaction and environmental issues are considered for perishable goods delivery for the first time. The paper proposes a novel bi-objective model that minimizes: 1) total customers waiting time, and 2) total travel cost. A restriction on maximum allowable carbon dioxide (CO2) emissions from transport in each route is considered as environmental issue in the problem. The proposed model is solved by simple additive weighting (SAW) method. Finally, the proposed model is applied to a real world problem in a supermarket chain. The results achieved by GAMS optimization software confirm the validity and high performance of the model in respect to the importance of the each objective function. Furthermore, the sensitivity analysis performed on the model reveals that less restrictive policies on carbon emissions lead to more total emissions but less total travel cost and customers waiting time.
    Keywords: Two-Echelon Vehicle Ruting Problem, (CO2) Emissions, Customers Waiting Time, Perishable Goods Delivery, Capacitated Vehicle Routing Problem
  • F. Aliakbari Nouri, M. Shafiei Nikabadi* Pages 532-542
    This study seeks to develop a fuzzy expert system to help managers in assessing their effectiveness and position of their business on the manufacturing excellence track. Assessment process is multi-dimensional in nature and there is a relationship between the different variables of the system. In addition, both quantitative and qualitative variables as well as the uncertainty in the statements of experts must be considered in the evaluation process. Fuzzy DEMATEL technique complies with these requirements by respecting the interrelation between the factors and by converting the qualitative judgments into quantitative values for decision. Due to these features, this technique is used in this study as the best technique for developing the decision tool. Evaluation criteria were identified through a literature review and interviews with experts. Multiple pairwise comparisons were performed to determine the weights of these criteria. Then, these weights were used to build If-Then rules of decision system. This reduced the supernumerary rules of the system, and provided a more real If-Then rule base. The decision support tool, presented in this study, enables decision makers to assess manufacturing excellence from different aspects such as External Excellence (EE), Internal Excellence (IE) and Technological Excellence (TE). The results of the implementation of this fuzzy expert system in Zar-Macaron Company (as a case study) were satisfactory.
    Keywords: Fuzzy Logic, Expert System, F-DEMATEL, Manufacturing Excellence
  • F. Kordhaghi, S. K. Sadrnezhaad* Pages 543-550
    Sol-gel technique was used to coat multiwall carbon nanotubes (MWCNTs) with anatase titania to increasing the surface area and improve the photocatalytic activity of TiO2. Room temperature ballistic conduct of MWCNT combined with semiconducting behavior of anatase brought about a photocatalytic improvement of ~37 % with respect to the highest methyl orange decolorization flair. For characterization and photocatalytic efficiency determination, X-ray diffraction (XRD), field emission (FE) scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS) and ultraviolet visible (UV-vis) spectroscopy were rehearsed. Attachment of anatase nanoparticles onto 30 wt % functionalized CNTs resulted in 99.72% methyl orange decolorization by 160 min irradiation with 8 W ultraviolet lamp. This value was fourfold greater than pure TiO2 nanoparticles and much greater than the values reported in the literature. This improvement was attributed to larger surface area, lower charge recombination and superior crystal structure and stimulated visible-light shifting due to presence of Ti O C bond.
    Keywords: Nano-photocatalyst, Anatase, Titanium Dioxide, Carbon Nanotube, Nanocomposite
  • H. Ghorbani, A. Abdollah Zadeh*, A. Poladi, M. Hajian Pages 551-557
    This paper is an attempt to synthesize nanostructured tantalum films on medical grade AISI 316L stainless steel (SS) using pulsed DC plasma assisted chemical vapor deposition (PACVD). The impact of duty cycle (17-33%) and total pressure (3-10 torr) were studied using field emission scanning electron microscopy (FESEM), grazing incidence x-ray diffraction (GIXRD), nuclear reaction analysis (NRA), proton induced x-ray emission (PIXE) and Rockwell indentation methods. The optimized deposition conditions for making the best film characteristics in terms of deposition rate, purity and maximum α-phase was recognized. Also, the results showed that using a near stoichiometric TaN interlayer in this technique improves the film adhesion strength and considerably increases Ta film purity. The NRA analysis results indicated that the pulsed DC-PACVD is capable of producing Ta films with negligible amount of residual hydrogen which makes films needless to post bake treatment.
    Keywords: Tantalum, Tantalum Nitride, AISI 316L Stainless Steel, Pulsed DC- Plasma Assisted Chemical Vapor Deposition, Characterization
  • P. S. Ravi*, A. Krishnaiah Azizuddin Pages 558-566
    The world is looking towards producing products which consume less power without compromising on quality of life. The increase in use of refrigeration and air conditioning appliances are contributing to global warming. The world wide temperatures are shooting up at an increasing rate. This paper presents a design of roll bond evaporator as the heat exchanger to provide cooling in room air conditioner. Presently all room air conditioners use tube and fin evaporators. This study presents roll bond evaporator as a power saving alternative to tube and fin evaporator. The experimentation has been done and comparative study of roll bond evaporator with that of tube and fin evaporator is presented. It was found out that while the tube and fin evaporator took 30 minutes to get a uniform temperature of 25 ºC in the room, the roll bond evaporator took only 25 minutes to get that uniform temperature, thereby saving 5 minutes of running of air conditioner.
    Keywords: Global Warming, Need for Power Saving, Roll Bond Evaporator
  • M. Malekzadeh*, B. Shahbazi Pages 567-574
    The spacecraft simulator robust control through H∞-based linear matrix inequality (LMI) and robust adaptive method is implemented. The spacecraft attitude control subsystem simulator consists of a platform, an air-bearing and a set of four reaction wheels. This set up provides a free real-time three degree of freedom rotation. Spacecraft simulators are applied in upgrading and checking the control algorithm's performance in the real space conditions. The LMI controller is designed, through linearized model. The robust adaptive controller is designed based on nonlinear dynamics in order to overcome a broader range of model uncertainties. The stability of robust adaptive controller is analysed through Lyapunov theorem. Based on these two methods, a series of the laboratory and computer simulation are made. The tests’ results indicate the accuracy and validity of these designed controllers in the experimental tests. It is observed that, these controllers match the computer simulation results. The spacecraft attitude is converged in a limited time. The laboratory test results indicate the controller ability in composed uncertainty conditions (existence of disturbances, uncertainty and sensor noise).
    Keywords: Spacecraft Attitude Control Simulator, Linear Matrix Inequality, Robust Adaptive Controller, Hardware in the Loop
  • N. Alagappan*, N. Karunakaran Pages 575-581
    A thermosyphon is an efficient heat transfer device, which transports heat using gravity for the evaporation and condensation of the working fluid. In the present study the Box-Benhnken (BBD) design approach was chosen for the Two-Phase Closed Thermosyphon (TPCT) with CeO2 nanofluid using 0.1% volume of Nanofluid with surfactant of ethylene glycol. The experiment resulted in identifying the optimised set of parameters for 405SS TPCT, to achieve lower thermal resistance and better heat transfer. This work gains significance in the sense that with the number of experiments, reliable model has been generated validated and further, the process has been optimised with one objective which is thermal resistance. To obtain the optimum condition, the response surface methodology (RSM) through Box – Behnken (BBD) was applied.
    Keywords: 405 Stainless Steel Two-Phase Closed Thermosyphon_CeO2 Nanofluid_Box – Behnken Design_Response Surface Methodology
  • R. Khamedi, I. Ahmadi*, M. Hashemi, K. Ahmaditabar Pages 582-590
    One of the most famous methods to predict the stiffness of short fiber composites is micromechanical modeling. In this study, a Representative Volume Element (RVE) of a beech wood flour natural composite has been designed and the orientation averaging approach has been utilized to predict its stiffness tensor. The novelty of this work is in finding the proper fiber orientation distribution function to increase the precision of the stiffness prediction of this kind of natural composites. The predicted results for stiffness with the micromechanical modeling are compared to the experimental test results and FEM results of beech wood flour/polypropylene composite.
    Keywords: Stiffness Prediction, Micromechanical Modeling, Orientation Averaging, Fiber Orientation Distribution Function
  • Vincent A. Balogun*, Isuamfon F. Edem Pages 591-596
    Mechanical machining processes are common manufacturing strategies to re-shape materials to desired specification. The mechanistic approach has revealed the mechanics of the machining processes with various parameters determined. The aim of this work is to investigate the impact of swept angle optimization and their influence on the specific cutting energy in milling AISI 1045 steel alloy. This is achieved by varying the step over at different feed rate values in order to determine the optimization criterion for machining. It was observed that an optimum swept angle of 31.8o was appropriate in the elimination of ploughing effect and reducing the specific cutting energy to an optimised minimum value. However, higher swept angle of 41.4o increases the specific cutting energy with a higher machine tool power. This is attributable to the reduction in the cycle time caused by shorter toolpath length. The results obtained further elucidate the knowledge base for the determinations of optimum parameters for sustainable machining and resource efficiency of manufactured products.
  • R. Singh, S. A. Rizvi*, S. P. Tewari Pages 597-603
    The basic aim of present study is to examine the effect of main friction stir welding (FSW) parameters on the quality of AA 6063 plate welds. Welding of AA6063 was carried out by a vertical milling machine, using different tools with a stationary shoulder and during the welding no external heating system was used. Different welding parameters studied were the tool rotational speed which varied from 2700 to 5400 (rpm), the traverse speed of table which varied from 12 to 17 (mm/min), and the tool shoulder diameter ranging from 17 to 22 mm. In the present research three levels, three factorial designs were used for optimization by taguchi approach. The results indicated that tensile strength of welded joint was increasing with rotational speed and decreasing with increasing transverse feed because frictional heat was directly proportional to rotational speed of tool.
    Keywords: Aluminium Alloys, Friction Stir Welding, Taguchi Technique, Mechanical Properties
  • M. Heidari* Pages 604-609
    This paper proposes a reduct construction method based on discernibility matrix simplification. The method works with genetic algorithm. To identify potential problems and prevent complete failure of bearings, a new method based on rule-based classifier ensemble is presented. Genetic algorithm is used for feature reduction. The generated rules of the reducts are used to build the candidate base classifiers. Then, several base classifiers are selected according to their diversity and the scale of them. Weights of the selected base classifiers are calculated based on a measure of support rate. The classifier ensemble is constructed by the base classifiers. The accuracy reached 98.44% which is 4.5% higher than that of the three base classifiers.
    Keywords: Fault Detection, Bearing, Classifier Ensemble, Genetic Algorithm
  • A. Kumar, R. Kumar, M. Ram* Pages 610-619
    In this paper, the authors investigated the various factors, which can affect the performance of a turbofan engine. For this, the various subunits of a turbofan engine like inlet duct, compressor, combustion chamber, liner, turbine, exhaust nozzle etc. are investigated to find its various reliability characteristics through Markov process and supplementary variable technique (SVT). The main advantage of this paper is that through the work one can identify exactly and accurately the factors/units, which mostly influence the performance of a turbofan engine. After investigation, it is concluded that the mean time to failure of angle of attack more frequently occurs throughout the operation of turbofan engine. In addition, it is analyzed that it is more sensitive with respect to the failure rate of inlet duct. Result shows that in order to optimize expected profit the maintenance team must control the service cost of various parts failure of the turbofan engine.
    Keywords: Turbofan Engine, Sensitivity Analysis, Reliability Measures, Maintenance Modeling, Cost Analysis, Supplementary Variable Technique
  • V. Morenov*, E. Leusheva Pages 620-626
    Aim of the project is efficiency increase of hard rocks destruction at borehole bottom by developing drilling mud solution and evaluation of its influence on drilling process. The article presents the results of studies directed on studying of drilling mud composition (the choice of reagent concentrations, taking into account the filtration properties, structural and rheological parameters, study of the temperature effect influence on the quality of the solution). Experiments of metallic indenter penetration into the glass sample at various number of strikes in the water and surfactant solutions are presented in the article. Paper also offers investigation devoted to development of clayless mud solution with surfactant addings, which will allow increase of hard rocks destruction efficiency. Results of industrial test trials of developed mud solution are also represented, showing implementation of developed drilling mud composition to increase productivity of drilling operations by maintaining high drilling speed and advance per bit.
    Keywords: Drilling Mud, Hard Rocks, Microfractures, Rock Destruction, Surfactant