INTERNATIONAL JOURNAL OF ENGINEERING
Year:2016 | Volume:29 | Issue:7 (TRANSACTIONS A: Basics)|Papers Count:18

In the present work forced convection flow in a channel partly filled with a porous media under asymmetric heat flux, boundary condition has been investigated. The porous material is distributed on the bottom wall of the channel. Darcy– Brinkman and LTNE model have been assumed in order to solve momentum and energy equations, respectively. Fully developed conditions are considered in order to solve velocity and the temperature fields. Due to the different configuration of porous media, new velocity profiles are introduced. The Nusselt number (Nu) is deduced in terms of the porous thickness(S), thermal conductivity ratio (k) and Darcy number (Da). The results illustrate that the fluid temperature in the clear region declines when the porous thickness grows at constant k. The temperature difference between the fluid phase and the solid phase decreases, as Bi increases. There are two stages for variation of Nu number with S and the optimum Nusselt thicknesses of the porous medium Sopt, Nu is found for different value of k and Bi. Moreover, at the particular value of S Nu number is independent of Bi and k for each Da number.

This paper investigates the reduction of acrylamide formation in potato crisps as a result of asparaginase treatment, using calcium chloride and sodium chloride solutions with different concentrations, immersion in different pH solutions, and different frying conditions. The main aim is to compare the reduction of acrylamide in potato crisps using two kinds of asparaginase enzyme; the first enzyme is commercial but the second is an enzyme made from Candida utilis specifically for food treatment. Before frying, samples were treated in one of following ways: Washing in distilled water (control I); Blanching in hot water; Immersion in commercial asparaginase (or asparaginase of Candida utilis) solution; Both blanching in hot water and immersion in commercial asparaginase (or asparaginase of Candida utilis) solution; Blanching in hot water plus immersion in medium temperature water (control II). While commercial asparaginase reduces acrylamide formation by 39%, asparaginase obtained from Candida utilis makes a higher reduction of 58% in potato crisps. However, both enzymes in combination with blanching inhibit much higher amount of acrylamide formation. Treatments with calcium chloride, sodium chloride, and citric acid have considerable effects on the content of acrylamide in fried potato. The maximum reduction of acrylamide is 95% caused by commercial treatment plus blanching.

The application of synthetic colors in textile industries and their entry into the water and groundwater is an environmental problem because of being very toxic material. The synthetic colors which are used in textile dyeing (plyacrilic and polyester) are usually dispersing colorants. They derive the azo and anthraquinone chemicals. Electro-Fenton process is an efficient technique which can degrade the recalcitrant wastewaters. The main goal of the present study was to examine the effect of iron electrodes (as a cheap and available material) on industrial textile wastewater treatment by electro-Fenton technique. The experiments were conducted to evaluate the effects of reaction time, current density, pH, H2O2/Fe2+ molar ratio and volume ratio of H2O2 to textile wastewater (TW) (ml/l) on the process. Response surface methodology (RSM) was used to consider the effects of five independent variables on the COD and color removal from the wastewater and optimize the operating conditions. The optimum conditions were obtained at reaction time of 71. 74 min, current density of 40. 11 mA/cm2, pH 2. 84, H2O2/TW of 2. 03 (ml/l), H2O2/Fe2+ molar ratio of 3. 89 for COD removal of 76. 33%. Furthermore, optimum conditions were found at reaction time of 75. 97 min, current density of 67. 04 mA/cm2, pH 2. 98, H2O2/TW of 1. 69 (ml/l), H2O2/Fe2+ molar ratio of 2. 98 for color removal of 79. 33%.

Crack growth analysis has remained one of the challenging problems in the fracture mechanics of structures. On the other hand, the fatigue crack growth is a common phenomenon in the components of structures like airplanes, navies and fluid storages where the fracture due to crack should be considered in the design of these structures. In this paper, the finite volume method (FVM) is extended for the modeling of static and fatigue crack propagation for two-dimensional problems. In the present method, due to the crack growth, no global remeshing is needed where only a cell dividing near the crack tip can be used which is easy to implement during the analysis. The accuracy of the method is studied by solving several benchmark problems and the results are compared with the available analytical and numerical results. It is observed that the results are good in accuracy comparing with those found in the references.

This paper demonstrates the design of an Arrayed Waveguide Gratings (AWG) based optical switch. In the design both physical and network layer analysis is performed. The physical layer power and noise analysis is done to obtain Bit Error Rate (BER). This has been found that at the higher bit rates, BER is not affected with number of buffer modules. Network layer analysis is done to obtain performance in terms of packet loss rate and average delay. Analysis presented in the paper clearly reveals that there is a minimum amount of power required, which is necessary for the satisfactory performance of switch both at physical and network layer.

In this paper a new phase-frequency detector is proposed using transmission gates which can detect phase difference less than 500ps. In other word, the proposed Phase-frequency Detector (PFD) can work in frequencies higher than 1. 7 GHz, whereas a conventional PFD operates at frequencies less than 1. 1 GHz. This new architecture is designed in TSMC 0. 13um CMOS Technology. Also, the proposed PFD achieves a capture range approximately twice that of conventional PFDs. The simulation results support the theoretical predictions. To validate correct performance of this novel PFD, it is then used in a conventional delay locked loop structure.

Today, a great deal of data is generated in the medical field. Acquiring useful knowledge from this raw data requires data processing and detection of meaningful patterns and this objective can be achieved through data mining. Using data mining to diagnose and prognose heart diseases has become one of the areas of interest for researchers in recent years. In this study, the literature on the application of classification algorithms for heart disease will be reviewed. The present study is an attempt to evaluate the studies carried out in this field so that the results of this review may lead to development of a clear view on the future studies. Here, first, the major medical tasks are specified and then, each article is investigated based on these tasks. Finally, some results, in terms of frequency algorithms in the use of classification algorithms, pre-processing and post-processing methods, will be provided. In this study, 49 articles obtained from similar studies with related subject matters, (from 2003 to 2015) are collected and reviewed. Obviously, the number of articles on applications of classification algorithms in heart disease is quite significant, therefore, it is impossible to review all of them in the present study. It is hoped that this study can provide results that pave the path for future research and further developments in this area.

In today's competitive markets, most firms try to reduce their supply costs by selecting efficient suppliers using different techniques. Several methods can be applied to evaluate the efficiency of suppliers. This paper develops generalized network data envelopment analysis models to examine the efficiency of two-tier suppliers under cooperative and non-cooperative strategies where each tier has its own inputs/outputs and some outputs of the first tier can be fed back to the second tier. Since the proposed models become nonlinear, an efficient heuristic method is proposed as an alternative solution, which can be used instead of existing time consuming methods like parametric linear programming approach. A numerical example is presented to exhibit the implementation of the proposed models. Also, for simulated data, results of proposed heuristic method and parametric linear programming are compared to demonstrate the validity and efficiency of the proposed approach.

To reveal the mechanism of the easy discretization and low damage in kernel dispersal, this paper analyzes the microscopic analysis of beak structures and finds that maxillary outside cells of the beak are dense and hard. Besides, the cuticle wrapping on maxilla of chicken's beak can reduce corn kernels damage in the discrete process of corn ear. From force test of corn ear, we found that value of x direction is the maximum, second is the y direction, and the value of z direction is the minimum. With reducing of water rate, the forces in three directions all decline. A 3D scanner is used to collect pointcloud data of rooster beak. Based on the point-cloud data, a roller is designed. Then the working process of discrete roller is analyzed. This research can provide a discussion for developing a corn thresher.

Bone drilling process is the most prominent process in orthopedically surgeries and curing bone breakages. It is also very common in dentistry and bone sampling operations. Due to complexity of the material that is machined, bone, and the sensitivity of the process, bone drilling is one of the most important, common and sensitive processes in biomedical engineering field. The most critical problem which can occur during bone drilling is increasing the process temperature above the allowable limit (47oC) which causes thermal necrosis or cell death in the bone tissue. In this study, an empirical model is developed to enable the surgeon to predict the temperature of the process based on tool’ s rotational speed, feed rate, tool diameter and effective interactions between these parameters. Experiments were designed and modeled using response surface methodology and to ascertain operation conditions, optimization was performed. Results show that within the range of the investigated variables, with an increase in the tool diameter and cutting speed, the rate of temperature change increases. It is noted that the behavior of the feed rate is complex; in this paper it is investigated precisely. The response surface model is able to predict temperature behavior based on the input parameters. The allowable range of parameters in bone drilling operation is introduced to obtain a quick and swift desirable operation.

The advent of 3D printers has been embraced globally within few years of its emergence. The surge in the acceptability of rapid manufacturing RM strategy can be attributed to the depletion and cost of natural resources, waste reduction and sustainability criterion of manufactured parts. This rapidly evolving 3D printing technologies is predicted to grow exponentially especially for the manufacture of customized and geometrically complex products. Therefore, it is appropriate to consider and optimize the resource efficiency of 3D printing technologies at this early stage of this technology development. In this work, the direct electrical energy demand of 3D printing (i. e. fused deposition modeling) was studied and a generic model proposed. The developed model was further validated with the Stratasys Dimension SST FDM in order to evaluate and ascertain the generic application of the model. This work is a further contribution to the existing foundation for electrical energy demand modeling and optimization for the rapidly expanding 3D printing processes.

Schlieren imaging in wind-tunnels is extensively utilized to study the effects of air on an airplane surface. One of the interesting subjects for research is to study the effects of speed change on the airplane surface. Speed change results in occurrence of shock waves, which are visualized as lines on Schlieren images. In this paper, we study the problem of detecting speed of after occurrence of a shock wave. For this, a two-level scheme is proposed which involves Schlieren image processing and classification. In the first stage, favorite features are extracted from a Schlieren image, which are represented as a feature vector. These features are related to the power and impact of the shock wave and are extracted through the proposed image processing schemes. In the second stage, a classification system is proposed, which categorizes Schlieren images according to their features. Each class represents one specific case of speed change. Experimental results are conducted in Wind-Tunnel laboratory of the Malek Ashater University of Technology. For evaluation, we have taken images, which lie in five classes. The results of applying the proposed system to the test images show a perfect accuracy rate.

The broken bearings, great noise and vibration often occurs with the small sugarcane harvester transfer case when it starts up working. To analyze the startup status of the transfer case conveniently and quickly, the finite element transient structure analysis is carried out. The virtual prototype technology to simulate the transfer case's startup dynamic process and measure the instantaneous load values is used. Stress distribution and load variation analysis results show that during startup, the stress concentration of node load increases rapidly with gear speed rising transiently. The maximum value lying on the underside of the bearing base goes beyond the allowable range before dropping sharply to approach the steady state with stress within the allowable range. Therefore, at startup the impact load of the transfer case increases far greater than in the steady state which deteriorates the structure stress condition seriously. The strength of the transfer case is then enriched by structural improvement accordingly to reduce maximum stress by 36. 8%, the maximum deviation by 18. 5% and the vibration up to 30%, improving the bearings working reliability notably.

In this paper, using vortex blob method (VBM), turbulent flow in a channel is studied and physical concepts of turbulence are obtained and discussed. At first, time-averaged velocities, u and v, and then their fluctuations are calculated. To clarify turbulence structures, velocity fluctuations u and v are plotted. It is observed that turbulence structures occupy different positions and move with convection velocity. To verify the second law of thermodynamics, averaged vorticity and its fluctuations as well as averaged entropy and its fluctuations are calculated. Contours of these fluctuations (  , s ) show that their positions coincide with the positions of turbulence structures and both positions move with the same velocity. Correlation coefficient of velocity fluctuations between two points, and temporal correlation coefficient at a point, which have significant role in understanding physics of turbulence, are calculated and plotted. Having obtained these coefficients, time and spatial micro-scales and then turbulence energy dissipation rate (  ) are obtained. Also, spatial-temporal correlation coefficients is calculated and then for turbulence structures microscale of time (memory), micro-scale of spatial (size) and convection velocity of structures are found. These scales estimate their life and size. Having obtained dual correlation coefficients, spectral studies of the velocity fluctuations, u and v , are performed, which include both frequency amplitude (related to temporal correlation coefficient) and wave number (related to special correlation coefficient). In fact, spectral study of fluctuations is Fourier transform (Cosine) of these fluctuations. Finally, dropping rate of this transform is compared with available data in turbulence literature. In this research, for the first time, the turbulence structures are visualized and presented by employing the vector of velocity fluctuations, vorticity and entropy generation fluctuations.

Size-dependent vibrational and instability behavior of fluid-conveying magneto-electro-elastic (MEE) tubular nano-beam subjected to magneto-electric potential and thermal field has been analyzed in this study. Considering the fluid-conveying nanotube as an Euler-Bernoulli beam, fluid-structure interaction (FSI) equations are derived by using non-classical constitutive relations for MEE materials, Maxwell’ s equation, and Hamilton’ s principle. Thereafter, taking the non-uniformity of the flow velocity profile and slip boundary conditions into consideration, modified FSI equation is obtained. By utilizing Galerkin weighted-residual solution method, the obtained FSI equation is approximately solved to investigate eigen-frequencies and consequently instability (critical fluid velocity) of the system. In numerical results, a detailed investigation is conducted to elucidate the influences of nanoflow and nano-structure small scale effect, non-uniformity, temperature change, and external magnetoelectric potential on the vibrational characteristics and stability of the system. This work and the obtained results may be useful to smart control of nano structures and improve their efficiency.

In this paper, the dynamic response of a micro-beam immersed in a fluid with regard to the free boundary of the operating fluid is investigated. In the other words, in addition to the kinematic compatibility on the boundary between micro-beam and its surrounding fluid, equations of the potential functions are modeled considering the free boundaries. It is also assumed that the micro-beam is a movable electrode, and the electrostatic force is used for the actuation of the system. Galerkin’ s method is utilized to solve the governing equations of the fluid-structure system. By imposing a fixed voltage to the system, in addition to investigating the geometrical effects, fluid type and the dimensions of the cavity, the effect of the free boundaries on the transient response of the system is studied. It is shown that the coefficient of relative permittivity of operating fluid, the length of the micro-beam, and the relative position of it to the lower side of the cavity have significant impact on the instability of system voltage. It is further shown that assuming the free boundaries in the modeling of the system, which is closer to the physical reality of the issue, increases the pull-in voltage.

Movement of sand particles in nature creates many problems for humans. One of these problems is deposition of particles on rails that decreases the speed of the train or in some cases hampers the reversal of the train rails. In this paper, the motion of sand particles over railway track embankment, and how these particles settle on railway tracks are investigated. Moreover, the performance of different fences of different heights and distances has been compared. It can be stated that particles velocity is highest on the embankment slope and up to the fence and lowest around the fence. Most of the particles deposition is on the slopes or near the embankment. Fences with different heights, distances (from the railway’ s longitudinal axis), and porosities are compared. Using the appropriate fence depends on the geographic and environmental factors, but in general the use of a fence with a height of 1 meter positioned at distance of 3 meters from the railway’ s longitudinal axis, and with 20% porosity is recommended.

Short-term production plans are the basis for operational mine production schedules. They concentrate on making long-term mine plans operationally feasible. Furthermore, some variables such as ore grade and tonnage govern mine production systems and cause uncertainty in the supply of raw materials to the mills. Due to the quality variation of material, short-term production optimization is an uncertaintybased problem. Feed quality is a prerequisite for the mill designer. It affects the mill efficiency and the type of measures with respect to environmental regulations. There is a need to control and to predict the quality of feed at the mine site to meet mill requirements, which is a complex problem. To deal with this issue a stochastic optimization model is developed to capture the effects of resource uncertainties on mine planning. In that regard, three performance indicators are defined and an optimized mining schedule is used to simulate the performance of these indicators throughout the mine-life. This will quantify the effects of geological uncertainty on short-term and long-term plans. The objectives of the model also include minimizing the deviation of expected quality and quantity from the required values. The methodology was illustrated using a case study on a surface gold mine in Iran. This approach leads to resilient decisions and better quality control. According to the results, introduced by the new production system, the probability of underproduction is reduced to 13%.