International Journal of Engineering
Volume:27 Issue: 5, May 2014

In this paper, water content from celery, corn, and sour cherry was removed through tunnel, fluidized bed, and fluidized bed with microwave dryers. One day before performing the experiments, the fruits were put in a refrigerator and ground into slices with average dimensions of 5×8×8 mm. For each experiment, 40 g of the samples were inserted in dryers. Moisture content in the samples was determined by weighting the samples using a balance. Experiments were accomplished under the air velocity of 1 to 3 m/s, the temperature of 40 to 60 oC, and the microwave power of 180 to 540 W. Influences of these operating conditions on the drying yield were presented and discussed. This study evidenced that the fluidized bed with microwave field resulted in the highest drying rate among the applied drying methods. The optimum temperature and air velocity for attaining the maximum drying performance were 60 oC and 1 m/s. In addition, the Exponential and Page’s models were used to fit the experimental data. The results showed that Page’s model had a good agreement with the experimental data.

In this study a modified entropy-based measure is presented for evaluating the serviceability level of water distribution networks in which the hydraulic uncertainties, such as flow rates in pipes, as well as the uncertainties due to mechanical parameters, like failure probabilities of links, are considered simultaneously. In the proposed entropy calculation method, the connectivity order of the network demand nodes is incorporated in the entropy calculations by defining a factor based on the ratio of the nodal demand to the total flow rates of all links of the network. The failure probability of the network links has been incorporated using a penalty function based on their failure probability in any specified hazard scenario. Then, this penalty function is inserted satisfactorily in the existing hydraulic entropy function (defined by previous researchers) of the network. In this way, the effect of mechanical behavior of links is also taken into account in the hydraulic entropy function of the network, while keeping its simplicity and applicability. By calculating the entropy values of some sample networks, it has been shown that the proposed entropy-based index is an efficient tool to find the optimum hydraulic layout for designing a new system, or to make decision on the best mitigation plan for an existing network subjected to different natural and man-made hazards.

CRC cards are unconventional methods for identifying and describing classes, behavior and their responsibilities and collaborators of class. Representation of three categories of class, responsibilities and collaborators can give proper image of the scenario. These cards are effective method for analyzing scenarios. With all positive features of CRC cards, these cards have some weaknesses such as failure to show details of operations and failure to evaluate them. These weaknesses guide us to model and evaluate these cards using petri nets. Basis of petri nets is on graph. In addition, these petri nets have mathematical structure and definitions, they have graphics. One of the other important characteristics of petri nets is their applicability which can be used for evaluating behavior and efficiency of a system. Therefore, our goal in this paper is to map CRC cards into stochastic petri net for evaluating and analyzing quality parameter of security.

Grid computing allows coordinated and controlled resource sharing and problem solving in multiinstitutional, dynamic virtual organizations. Moreover, fault tolerance and task scheduling is an important issue for large-scale computational grid because of its unreliable nature of grid resources. Commonly exploited techniques to realize fault tolerance is periodic checkpointing that periodically saves the job’s state. But an inappropriate checkpointing interval prevails to delay in the job execution, and reduces the throughput. With that concern, this paper endeavors to ensure better performance on computational grid with more effective and reliable fault tolerant system using a novel Stability Assessment Metamorphic Approach (SAMA). Here, the strategy used to attain fault tolerance is by adapting the checkpoints depending on the current status and past failure information about the resources dynamically, which is being maintained in the information server. The effective scheduling process can be achieved by fault tolerance based scheduling that involves the determination of deviation rate of all nodes using some high-stability assessment constraints. This evinces the job to be accomplished within the deadline with improved throughput and paves a way for making the grid environment trustworthy.

This paper shows how we can make advantage of using genetic programming in selection of suitable features for automatic modulation recognition. Automatic modulation recognition is one of the essential components of modern receivers. In this regard, selection of suitable features may significantly affect the performance of the process. Simulations were conducted with 5db and 10db SNRs. Test and training data released from real ones were recorded in an actual communication system. For performance analyzing of the proposed method, a set of experiments were conducted considering signals with 2PSK, 4PSK, 2FSK, 4FSK, 16QAM and 64 QAM modulations. The results show that the selected features by the model improve the performance of automatic modulation recognition substantially. During our experiments, we also reached the suitable values and forms for mutation and crossover ratio, fitness function as well as other parameters for the proposed model.

In this paper, a microstrip antenna on a suspended substrate with capacitive feed is presented. capacitive feed is created by a slot within the rectangular patch around the feed point. The proposed antenna exhibits a much higher impedance bandwidth of about 47% (S11 < −10 dB). Effects of key design parameters such as the air gap between the substrate and the ground plane, the gap width between radiator patch and feed point, and the location of the feed point on the input characteristics of the antenna have been investigated and discussed. A prototype of the antenna is also fabricated and tested to verify the design. Measured characteristics of the antenna are in good agreement with the simulated results.

In this paper, a new current-controlled conveyor (CCCII) in complementary metal-oxide semiconductor (CMOS) technology is presented. It features, low supply voltage (±0.7), low power consumption, low circuit complexity, rail to rail operation and wide range parasitic resistance (Rx). The circuit has been successfully employed in a multifunction biquad filter. Simulation results by HSPICE show high performance of the circuit and confirm the validity of the proposed design technique.

In this paper, a statcom without any energy storage devices is proposed to compensate network voltage during disturbances. This statcom utilizes a matrix converter in its topology which eliminates the DClink capacitor of conventional statcom. The modulation method for matrix converter which is used in this paper is space vector modulation. There are some methods to improve power quality for sensitive loads. In this paper, Combination of improved multi objective Particle Swarm Optimization (PSO) algorithm with fuzzy membership function is used to determine the PI coefficients. The simulation results indicate the efficiency of proposed method.

Each system has its own definition of reliability. Reliability in mobile ad-hoc networks (MANET) could be interpreted as, the probability of reaching a message from a source node to destination, successfully. The variability and volatility of the MANET configuration makes typical reliability methods (e.g. reliability block diagram) inappropriate. It is for the reason that no single structure or configuration represents all manifestations of a MANET. Thus, new methods should be developed to analyze the reliability of this new networking technology. In this paper, we first introduce a simple technique for calculating reliability in MANET which is appropriate for small size of the networks. It is shown that this way is time consuming and costly in a larger network domain. Then, a heuristic method based on a Monte Carlo simulation is presented, which has less overall time consuming even for large size of the network. For a better investigation, the effect of network size (number of nodes) and probability of link existence have been studied and evaluated on network reliability for the proposed method.

Natural images, textures and photographs are likely to be impaired by stains. As a result a substantial portion of the image remains blurred. However, a method called region completion is adopted to fill in the tainted part using the information from the portion left unblemished by stains. A novel method to perform this operation is proposed in this paper. The three significant stages involved in the proposed work are patch size selection, matching patch identification using multiresolution transforms such as Wavelet and Contourlet Transforms, and finally minimum cost path determination. The aforesaid methods perform well for different varieties of texture images. The results obtained using the proposed method is encouraging and reasonable in some cases.

Ethanol sensitivity of zinc oxide (ZnO) thin film has been studied in present work. Semiconductor thin films of zinc oxide (ZnO) were deposited onto soda lime glass substrates by the sol–gel method and dip-coating technique. The ZnO sol was synthesized by dissolving zinc acetate, Zn (CH COO)2.2H2O in ethanol, and then adding triethanolamin (TEA). The as-coated films were preheated at 150 ºC for 10 min and annealed at 500 ºC for 1 h in air ambiance. Zinc oxide thin films were analyzed by field emission scanning electron microscopy (FE- SEM) and X- ray diffraction (XRD). In addition, Gas sensitivity of the zinc oxide thin film was determined by electrical sheet resistance measurements. The sensitivity to ethanol was remarkable and response and recovery time were only 8 sec, and 4 sec, respectively.

In this paper, deposition of ceramic nanoparticles on in-plane electrodes under the influence of AC electric fields is investigated. Particles are dispersed in a non-aqueous suspension and the frequency range is between 0.01 Hz ot 10 kHz. Analysis of the particle response to the applied field is a difficult task due to the mutual effect of electric- and hydrodynamic force which are present in the system. In this work, however, we show the possibility of dividing the frequency range into four domains with four distinct governing mechanisms. Possible mechanisms are suggested and dominant forces are determined for each domain. In situ optical microscopy observations as well as numerical calculations are used for three dimensional visualization of nanoparticles´ movement dispersed in liquid medium. New applications such as micro-patterning and sorting ceramic particles are introduced for the first time.

In this study, mechanochemcical process (MCP) is applied to synthesize ultrafine TaC powders. In this research, nanopowder composite TaC-TaB2 was produced using mixtures of tantalum carbide and boron carbide as raw materials, via mechanochemical process. The phase formation characterization during the process was utilized by X-ray diffractometry (XRD). The morphology of synthesized powder was studied using scanning electron microscopy (SEM).

The simulation of the store separation using the automatic coupling of dynamic equations with flow aerodynamics is addressed. The precision and cost (calculation time) were considered as comparators. The method used in the present research decreased the calculation cost while limiting the solution error within a specific and tolerable interval. The methods applied to model the aerodynamic forces are timedependent dynamic meshes and quasi-static methods. In the time-dependent method, a dynamic unstructured tetrahedral mesh approach using combination of spring-based smoothing and local remeshing is employed in respect of bodies motion with an implicit, second-order upwind accurate 3-D Euler solver. In this method, a 6dof dynamic code is coupled with the flow solver to update the store trajectory information. In the quasi-static method, a 3-D implicit, steady state Euler solver is automatically integrated with a grid generation software and a 6dof dynamic code. Although the timedependent method is more precise and reliable, it is not proper and appropriate for the initial design of the separation system due to its high cost. The quasi-static solution is very fast, but unable to simulate realistically because of not satisfying the problem conditions due to solution divergence as the store speed increases. The method used in the present research decreased the calculation cost while limiting the solution error within a specific and tolerable interval. In this way, the time step can be enlarged, the solution can be carried out with a few calculation points, and the solution can have considerably more speed with a limited error magnitude. Simulation of the store separation using the automatic coupling of dynamic equations with flow aerodynamics with the new Low-Cost method is the innovative aspect of this paper. To validate the solution method, the transonic store separation was simulated that agreed well with the wind tunnel test outcomes.

The first row rotating blades of four axial-flow compressors fractured prematurely. Previous investigations had shown that the atmosphere of the site contained corrosive compounds which lead to an increase in possibility of pitting of the blades. It was also revealed that the crack was originated from two corrosion pits. Thus, this work is conducted to ascertain which of the fatigue or stress corrosion cracking (SCC) mechanisms is predominant in transition of pits into initial cracks. To this end, experimental, numerical and theoretical studies are considered. Replica testing, Scanning Electron Microscope (SEM) and fractography of the broken blade indicate that the pits join together and make one bigger pit under SCC mechanism which reduces the failure time. 3-D models of the pitting on the blade under existing forces are analyzed by ABAQUS software. The simulation results show the location of maximum stress concentration inside one of the pits which is compatible with the location of initial SCC crack. Theoretical and numerical analysis show that stress intensity range (ΔK) around the pits is smaller than threshold stress intensity range (ΔKth); thus, cracks initiate and propagate at the mouth of the pits under SCC mechanism. Then, the pits join together and make one equivalent pit, so that ΔK reaches the ΔKth and finally crack propagates under fatigue mechanism.

In this investigation, the structure of one-dimensional flame propagation in uniform cloud of volatile organic particles has been analyzed in which the structure of flame is divided into three zones. The first zone is preheat zone which is divided into three subzones itself. In the first subzone (heating), particle cloud is heated until the moist particles reach to vaporization temperature (water vapor). In the next subzone (drying), particle moisture comes out, and in the final subzone the pyrolysis phenomenon takes place. The second zone is the reaction zone, and the last one is the post-flame zone. In this research, an analytical method is used in order to solve the governing equations of particle cloud combustion in aforementioned zones. The overall investigation of this study leads to a non-linear burning velocity correlation. Consequently, the results show that a decrease in particle moisture content or an increase in equivalence ratio (j u) or Lewis number causes to increase in moisture evaporation and devolatization rates, and consequently both flame temperature and burning velocity increase.

In this research, a nonlinear strain hardening mathematical model is proposed for 7075 aluminium alloy (A7075). Uniaxial tension-compression experimental data are used to figure out a suitable model to study the Bauschinger effect factor, BEF. Hence, uniaxial tension-compression tests on specimens having 12.5 mm and 6 mm diameters were carried out by an Instron servohydraulic machine and the results were compared. In this paper several factors including Young’s modulus, the amount of offsets to determine yield point and BEF were studied. Besides, BEF in the aluminium tubes made from A5083 and A7075 alloys were compared. This model will be employed to predict residual stress and fatigue life in autofrettaged tubes.

A solar drier assisted with evacuated tube collector is designed and developed to study and examine the drying Kinetics of muscat grapes in Thanjavur, Tamilnadu, India. During the drying period, temperature at various places, relative humidity, wind velocity and mass of the sample are measured on hourly basis. The outlet temperature of the collector and temperature within the chamber varies from 74-130 ºC and 50- 87 ºC respectively, while the ambient temperature ranges from 29.5-33.2 ºC. Solar insulation recorded during these days ranges from 155.6-1115 W/m2. The designed drier takes 14 hours to reduce the moisture content of muscat grapes from 78% to 9.5% (wb) to ensure safe storage. It is found that the whole drying process exists in falling-rate period. The maximum drier efficiency for muscat grapes is found to be 29.92% during the drying period. Six thin-layer drying models have been used to fit the experimental moisture ratio obtained for muscat grapes by nonlinear regression analysis using IBM SPSS 20 statistical package. According to the results, Page model shows a good fit with highest correlation (R2 = 0.991), lowest reduced chi-square (χ2 = 0.001) and lowest root mean square error (RMSE = 0.0297).