فهرست مطالب

International Journal of Engineering
Volume:31 Issue: 12, Dec 2018

  • TRANSACTIONS C: Aspects
  • تاریخ انتشار: 1397/10/22
  • تعداد عناوین: 16
|
  • Z. Nourbakhsh Amiri, G. D. Najafpour, M. Mohammadi, A. A. Moghadamnia Pages 1991-2000
     Ginger is one of the commonly used spices that has been exhibited to have pharmaceutical activities. These therapeutic properties are mainly attribute to gingerols and shogaols. To extract these bioactive compounds, subcritical water extraction (SWE) was employed as a green method. The influence of adding co-solvents, temperature, retention time and particle size on extraction yield were investigated. In addition the impact of ultrasonic and enzyme pretreatment was studied. Enzyme-assisted SWE with 2% ethanol as co-solvent and using ginger having particle size of 1mm, operated at 130°C and 20 bars for 30 min, is approved as optimized condition. At this condition, the total obtained polyphenol content and the concentration of total gingerols and shogaol were 5325 µg GAE/g dried ginger and 2990.5 µg bioactive/g dried ginger, respectively. Pretreatment of ginger powder with α-amylase prior to SWE, resulted in a 2.8 and 2.22 folds increase in total polyphenol content and concentration of total gingerols and shogaol, respectively. SEM analysis was conducted to evaluate the effect of pretreatment on morphology of ginger and analyze the extraction process.
    Keywords: Ginger, Gingerol, Shogaol, Subcritical Water, Enzyme Pretreatment
  • R. Davarnejad, R. Pishdad, S. Sepahvand Pages 2001-2008
    One of the famous dyes is methylene blue (MB) which is a symbol of hazardous dyes. In this research, methylene blue was adsorbed using the blends of saffron petals with activated carbon. Five independent variables involving pH (2-13), contact time (5-270 min), saffron petals powder dosage (0.1-10 g/l), initial concentration of methylene blue solution (20-300 ppm) and activated carbon dosage (0.1-10 g/l) for methylene blue adsorption were studied. For this purpose, pure saffron petals powderand its blends with activated carbon were used to adsorb methylene blue with various concentrations from water at the above ranges. The Central Composite Design (CCD) under Response Surface Methodology (RSM) was applied to estimate the independent variables effects on the methylene blue adsorption. The optimum conditions for the 96.5% of removal were experimentally found at pH of 10.5, initial methylene blue concentration of 85.9 ppm, saffron petals powder dosage of 7.07 g/l, contact time of 182.05 min and activated carbon dosage of 7.35 g/l while the operating conditions for the maximum removal of 95.3% were experimentally obtained at pH of 10.5, initial methylene blue concentration of 83.1 ppm, saffron petals powder dosage of 7.77 g/l, contact time of 64.7 min and activated carbon dosage of 7.77 g/l. It is concluded that saffron petals powder (as a waste) with activated carbon is able properly adsorb methylene blue.
    Keywords: Adsorption, Biomass, Methylene Blue, Wastewater
  • R. Nikbakht, F. Behnamfar Pages 2009-2015
    Passing underground trains induce vibrations transmitted to the ground surface and the nearby structures. Ordinarily, these vibrations do not result in structural damage but can harm nonstructural elements and disturb the occupants. These effects are more pronounced when evaluating buildings like hospitals, laboratories, museums, etc., and their assessment is an important design need. To respond to this requirement, in this paper response spectra for passing trains moving with different velocities are calculated. Using these spectra, without resorting to the time consuming and costly analysis of a tunnel-soil system under moving loads, the maximum structural responses can be calculated rapidly. To make this end, the soil-tunnel interaction is modeled using a three dimensional (3D) finite difference scheme under the standard moving train loads. The dynamic analysis of such a system results in the ground surface vibration time histories at different distances from the tunnel axis. Then the maximum values of acceleration, velocity, and displacement responses are calculated for a single degree of freedom (SDOF) dynamical system. The above calculations are accomplished for different standard trains, train velocities, tunnel depths, distances from tunnel, and soil types, and are presented as response acceleration, velocity, and displacement spectra.
    Keywords: Underground Tunnel, Soil-tunnel Interaction, Surface Vibrations, Response Spectra Surface Structures
  • F. Mohamed Nazri, C. Kian Yern, M. Moffed Kassem, E. Noroozinejad Farsangi Pages 2016-2021
      Soft storey building is popular due to the functional and aesthetic purpose, despite its weakness in resisting seismic excitation. Nonlinear Static (Pushover) Analysis (POA) is a time saving and simple assessment procedure prosposed in Eurocode 8 (EC8). However, its reliability in designing structure still remains a question. At the first stage, seismic performance of several building models using POA in EC8 is assessed. Later on, empirical accuracy of fragility curves generated by POA (using SPO2FRAG software) is studied and verified through Incremental Dynamic Analysis (IDA) results. Four models of regular and soft storey frame of 5- and 11-storey varying heights were designed according to Eurocode 2 (EC2) and (EC8). The simulation is performed in a NL platform to carry out POA and IDA. Capacity curve obtained is served as main input in SPO2FRAG software to generate fragility curve. Then, IDA is performed to generate IDA and fragility curves. Peak ground acceleration, PGA was converted into corresponding Sa(T1) using design spectrum from EC8. Performance levels of Life Safety (LS) and Near Collapse (NC) proposed by Vision-2000 have been the main interest in this study. Results shown that the base shear calculated by using Lateral Force Method in EC8 is adequate. Fragility curve generated by SPO2FRAG, has good comformity with IDA-based fragility estimation for regular 5-storey model; however, some deviation is observed for soft storey model (5-storey). All 11-storey frames shown unsatisfactory match of fragility curves from what was generated by SPO2FRAG, compared to IDA results.
    Keywords: Pushover Analysis, SPO2FRAG, Soft Storey Structure, Fragility Curve, Eurocode, Performance Level
  • H. AL, Naely, Z. Al, Khafaji, S. Khassaf Pages 2022-2027
    Nowadays, developed and applied hydrology become very important thing in the life due to the wide verity advantages for the applications of this field. Hydraulic Structures such as crump weir are placed in channels to estimate or measure flow rate and flow control devices. In this study there is a new performance for crump weir which appears by adding opening holes in the model of crump weir. Opening holes are working as an energy dissipater and as an improver for the discharge coefficient (Cd). Where the discharge coefficient (Cd) is improved and recorded a higher values in comparison with conventional weir under the same laboratory conditions. The twenty-eight laboratory experiments were carried out using free flow in a horizontal channel of 12 m length, 0.5 m width and 0.35 m depth for a wide range of discharge. The experimental results indicated that Cd values increase by increasing the number opening holes in body of crumb weir. Thus; increasing the holes numbers from one to two and three holes) increase Cd value about (10, 11 and 13%), respectively as compared with traditional weirs without opening holes. On the other hand, The results revealed better flow behaviour for two holes model than one and three holes, the flow is more stable and the transition flow regime has less instabilities and Energy dissipation rate is the maximum. Thus; the weir crumb with three voids are not stable and it was not easy to localized it in the channel.
    Keywords: Crump Weir, Discharge Coefficient, Energy Dissipation, Hydraulic Jump, Hydraulic Structure, Open Channels
  • S. Moameri, N. Samadinai Pages 2028-2036
     In this paper, we propose a novel fuzzy expert system for detection of Coronary Artery Disease, using cuckoo search algorithm. This system includes three phases: firstly, at the stage of fuzzy system design, a decision tree is used to extract if-then rules which provide the crisp rules required for Coronary Artery Disease detection. Secondly, the fuzzy system is formed by setting the intervals for fuzzy variables and extracted rules. Finally, Cuckoo Search algorithm is used to optimize fuzzy membership functions. The accuracy of our proposed system is evaluated using Cleveland Cardiac Patient Database. The detection rate is 93.48% employing optimized membership functions. Also, 85.76% accuracy is obtained for predicting the risk of coronary artery disease. The superiority of proposed system is obvious by comparing it to the previously methods; it is more accurate and is also easier to implement.
    Keywords: Coronary Artery Disease, Fuzzy System, Cuckoo Search, Heart Disease, Decision Tree
  • D. Mehrotra, D. Nagpal, R. Srivastava, R. Nagpal Pages 2037-2043
    With the advancements in mobile technology and its utilization in every facet of life, mobile popularity has enhanced exponentially. The biggest constraint in the utility of mobile devices is that they are powered with batteries. Optimizing mobile’s size and weight is always the choice of designer, which led limited size and capacity of battery used in mobile phone. In this paper analysis of the energy consumption of some popular mobile apps is done using data mining technique. A large variety of mobile apps with differently functionality are executed on a smart phone. The power consumption of these apps is measured using Power Tutor. For holistic analysis these mobile apps are executed in different environment, which are created by varying the setting and internet facilities. Fuzzy Clustering approach is used to club the mobile apps based on similarity of the behaviour with respect to power consumption. Power consumption behaviour for each cluster and apps lying in overlapping zone is discussed in detail. The study gives the insight that power need of an app is dependent on the environment and code which can be used by app developers for creating an optimized energy app.
    Keywords: Power Consumption, Mobile Applications, Green Mining, Fuzzy Clustering, Power Tutor
  • K. Gorgani Firouzjah Pages 2044-2051
    This paper presents a novel fault location method for series compensated transmission lines. It is established based on synchronized voltages sampling and Thevenin impedance from both ends of series compensated transmission line. The method is based on the use of phasor measurement units (PMU) technology which is aimed to be independent of current measurements, fault type, fault resistance, fault inception angle and line loading angle. This method includes two subroutines for the faults located on the right and left sides of series capacitor (SC). Lumped modeling is considered for compensated transmission line with SC equipped with metal oxide varistor (MOV) arrester. The nonlinear behavior of SC-MOV system is investigated in the analysis. Proposed current independent fault location algorithm has been thoroughly tested using signals taken from simulations. According to the results, the percentage errors for the fault distances estimation are in proper ranges.
    Keywords: Fault Location, Series Compensated, Synchronized Voltage Measurement, Current Transformer Elimination, Series Capacitor
  • S. Yazdanparast, A. Sadegheih, M. Fallahnezhad, M. Abooie Pages 2052-2058
    This study aimed at presenting a method for formulating optimal production, repair and replacement policies. The system was based on the production rate of defective parts and machine repairs and then was set up to optimize maintenance activities and related costs. The machine is either repaired or replaced. The machine is changed completely in the replacement process, but the production rate of defective parts decreases in the repair process. The repair time and number of repairs will affect this process. The aim of this study is to find decision variables that minimize the final cost of repair, replacement, maintenance and prevention of failures in a given time horizon. As a case study, the variables were evaluated at Arak Pishgam Company to achieve optimal conditions. The proposed model was developed based on the semi-Markov decision process (SMDP). In addition, stochastic dynamic programming model was used to achieve optimal conditions.
    Keywords: Machine Replacement, Stochastic Dynamic Programming, Stochastic Deterioration
  • M. B. fakhrzad, P. Talebzadeh, F. Goodarzian Pages 2059-2067
    In this paper, developed a new multi-product, multi-period, and multi-level closed-loop green supply chain planning model under uncertain conditions. The formulated model consists of five objective functions, which minimize the cost of the supply chain, minimize the CO2 emission of transportation vehicles, maximize the reliability of manufacturing and distribution centers, maximize the reliability of the transportation system, and maximize the level of service provided. Therefore, the problem of model formulated as a multi-objective mixed integer nonlinear programming. Also, since the proposed model is complex and NP-hard in large size, therefore, for the investigation of the results, we have used a Non-Dominated Sorting Genetic II Algorithm (NSGA-II). In addition, the small of size results of the problem achieved by GAMS software. Therefore, we try to solve these problems by analyzing and comparing them with the help of these algorithm. For this purpose, various size has been considered.
    Keywords: Green Closed-loop Supply Chain, Uncertainty, Reliability, NSGA-II Algorithm
  • R. Dabbagh, M. Khoshsirat, A. Bozorgi, Amiri Pages 2068-2076
    One of the main activities of humanitarian logistics is to provide relief items for survivors in case of a disaster. To facilitate the procurement operation, this paper proposes a bidding framework for supplier selection and optimal allocation of relief items. The proposed auction process is divided into the announcement construction, bid construction and bid evaluation phases. In the announcement phase, the bidder (purchaser or relief organization) invites certain suppliers to the auction. Next, the construction phase is formulated as a bi-objective fuzzy model from the perspective of suppliers. This phase provides the bidder with several suggestions, each of which containing the amount, price, and lead time of the delivery of relief items. Then, in the evaluation phase, the bidder determines the winners and optimally assigns orders by a multi-objective fuzzy model. Each of the fuzzy mathematical models in the paper is formulated under the uncertainty of parameters and is then solved by a two-stage fuzzy approach. Finally, to illustrate the validity and applicability of the proposed model, a numerical example is provided and its result is analyzed.
    Keywords: Humanitarian Relief Chain, Procurement, multi-attribute Reverse Auction, mathematical Modeling, Augmented ?-Constrained Method
  • R. Ghandali, M. H. Abooie, M. S. Fallah Nezhad Pages 2077-2084
    Maintenance can be the factor of either increasing or decreasing system's availability, so it is valuable work to evaluate a maintenance policy from cost and availability point of view, simultaneously and according to decision maker's priorities. This study proposes a Partially Observable Markov Decision Process (POMDP) framework for a partially observable and stochastically deteriorating system in which inspection and maintenance optimal policies of Condition Based Maintenance (CBM) must be determined to maximize the average profit and availability of the system simultaneously. A recent exact method named Accelerated Vector Pruning method (AVP) and some other popular estimating and exact methods are applied and compared in solving such problems.
    Keywords: Availability-profit Maximization, Condition Based Maintenance, Partially Observable Markov Decision Process, Stochastically Deteriorating
  • M. Toghraei, H. Siadati Pages 2085-2091
    Optoelectronic properties of hematite (α-Fe2O3) as a photoanode and the required over-potential in photo-assisted water splitting has been improved by presence of Co-Pi on its surface. In order to increase the lifetime of the photogenerated holes and lower the applied bias, cobalt-phosphate (Co-Pi) on nanostructured α-Fe2O3 by electrodeposition was deposited. The nanostructure morphology of the α-Fe2O3 was confirmed by XRD and SEM. After depositing four different thicknesses of Co-Pi on α-Fe2O3, their photo-electrochemical (PEC) property was determined using linear sweep voltammetry (LSV) and chronoamperometry. The SEM and EDX results showed a complete coverage of Co-Pi on α-Fe2O3 and that the Co:P ratio was approximately 1:1.9 for the best produced catalyst. The highest performance of about 200 mV decrease in the onset potential was achieved for the 30-minutes electrodeposited sample. The Co-Pi/α-Fe2O3 catalyst showed an enhancement of 100% of photocurrent compared to the bare α-Fe2O3.
    Keywords: Solar Water Splitting, Photoanode, Hematite, Co-Pi, Electrodeposition
  • P. Afzali, M. Yousefpour, E. Borhani Pages 2092-2101
    In this study, a wide range of combined ageing treatments and cold work deformations in the Al 4.2 wt% Ag alloy matrix were proposed, aiming to investigate the effect of defects such as precipitates (Ag2Al plates) and dislocations on the mechanical and electrochemical behavior of Al–4.2 wt% Ag alloys. Further reductions of thickness from 10 to 60%, decreases the mean size of Ag2Al plates, along with a denser distribution. The inductive loop at lower frequencies in Nyquist plot attributed to localized corrosion that clearly testified the fluctuations of the anodic branch in the Tafel diagram and the FE-SEM images for the presence of pitting corrosion. Additionally, the pit propagation grade expands repetitively with cold work reduction and fragmentation of pre-precipitates. This was related to an extreme amount of dislocations induced by deformation and fragmented pre-precipitates, which created more preferable locations for the nucleation of pits. Furthermore, Energy Dispersive X-ray Spectroscopy of pits, revealed that the presence of Al-Ag containing particles acted as cathodic sites and caused the anodic matrix dissolution.
    Keywords: Corrosion, Pitting, Al-Ag, Cold Work Deformation, Precipitation
  • S. Abbasi, M. Zeinali Pages 2102-2108
    Development of autonomous underwater vehicles (AUVs) which meets the design constraints and provides the best hydrodynamic performance is really an important challenge in the field of hydrodynamics. In this paper a new profile is used for designing the hull of AUVs. The nose and tail profiles of an AUV using presented profile is designed such that it can properly consider the length constraints due to arrangement of different components in the AUV body. In the current work the flow around an AUV is simulated numerically. Then, the nose and tail profiles are changed in order to investigate the contribution of each of these elements on pressure distribution over the body as well as total drag of the underwater vehicle. The effects of nose and tail profiles on hydrodynamic performance of body were evaluated for this underwater vehicle. Results showed that modified nose and tail shape improved the hydrodynamic behavior of AUVs effectively
    Keywords: Autonomous Underwater Vehicles, Hull Shape Design, Multi-objective Optimization
  • L. Zhao, C. Zhou Pages 2109-2114
    To facilitate the damping matching of dampers for vehicle passive suspensions, this paper proposes an analytical matching method of the optimal piecewise linear damping characteristics curve. Based on the vehicle vibration model, taking the suspension dynamic deflection as the constraint, by the vibration acceleration and the wheel dynamic load, an objective function about the relative damping coefficient was created. Using the integral mid-value law, an analytical formula of the optimal relative damping coefficient was established and the analytical matching method of the piecewise linear damping characteristics curve was presented. With a practical example, the effectiveness of the proposed matching method was validated by road test. The results showed that the method presented is workable, which has important reference value for fast damping matching of vehicle passive suspensions.
    Keywords: Passive Suspension, Relative Damping Coefficient, Characteristics Curve, Integral Mid-value Law, Analytical Matching