Showing 8 results for Ayyoubzadeh
Volume 9, Issue 3 (Summer 2021)
Abstract
Aims: Dermatoglyphic is the study of skin patterns on hands and feet. It has been shown in some studies that specific finger patterns could be a risk factor for breast cancer. Thus, this study aims to evaluate fingerprint patterns and other easy-to-obtain features in the risk of breast cancer.
Instrument & Methods: This descriptive study was conducted in 2020. A dataset containing 462 records included female patients in Imam Khomeini Hospital Complex, Tehran, Iran. The factors' weight was determined by the Information Gain index. Predictive models were built once without fingerprint features and once with fingerprint features using Naïve Bayes, Decision Tree, Random Forest, Support Vector Machine, and Deep Learning classifiers. RapidMiner 9.7.1 Software was used.
Findings: The most important factor determining breast cancer were age, having a child, menopause situation, and menopause age. The best performance was the Random Forest model with accuracy and Area under Curve of a Receiver operating characteristic of 84.43% and 0.923, respectively. The fingerprint patterns feature increased the RF accuracy from 79.44% to 84.43%.
Conclusion: An early breast cancer screening model could be built with the use of data mining methods. The fingerprint patterns could increase the performance of these models. The Random Forest model could be used. The results of such models could be used in designing apps for self-screening breast cancer.
Volume 11, Issue 4 (Number 4 - 2009)
Abstract
The purpose of this paper is to present a 2D depth-averaged model for simulating and examining unsteady flow patterns in open channel bends. In particular, this paper proposes a 2D depth-averaged model that takes into account the influence of the secondary flow phenomenon through calculation of the dispersion stresses. The dispersion terms which arose from the integration of the product of the discrepancy between the mean and the actual vertical velocity distribution were included in the momentum equations in order to take into account the effect of the secondary current. This model used a time-splitting method for solving advection, diffusion and other momentum equation terms. The proposed model uses an orthogonal curvilinear coordinate system efficiently and accurately to simulate the flow field with irregular boundaries; it also used a finite volume projection method approach for solving the governing equation in a staggered grid. Two sets of experimental data were used to demonstrate the model's capabilities. The comparison of the simulated water surface elevation with the measurements shows good agreement and indicates that inclusion of the dispersion terms improved the simulation results.
Volume 12, Issue 1 (3-2012)
Abstract
The flow at a channel bifurcation is turbulent, highly three-dimensional (3D) and has many complex
features. There is transverse motion accompanying the main flow and an extensive separation zone
that develops in the branch channel. There are two complex flow regions along the intake channel: one
is the separation zone and the other is the region in which helical motion of water particles forms. This
separation occurs because the flow entering the branch channel has considerable momentum in the
direction of the main channel flow. This zone causes hydraulic and sedimentation problems that must
be known before designing the system. This necessitates a deeper insight into the flow patterns and
shear stress distributions near the solid boundaries. In this research, 3D flow patterns at lateral
diversion were investigated experimentally and numerically. The experimental investigation was
carried out at a T-junction, formed by two channels with rectangular cross-sections. The width of
lateral intake to the main channel was 0.4. 3D velocity measurements were obtained using Acoustic
Doppler Velocimeter at junction region for 11%, 16% and 21% discharge ratios. Fluent mathematical
model was then used to investigate the dividing open-channel flow characteristics. Turbulence was
modeled by Two Equation (k-ε, k-ω) and Reynolds Stress (RSM) turbulence models. The predicted
flow characteristics were validated using experimental data and the proper model was selected for
hydrodynamic and parametric studies. Within the main channel, good agreement was obtained
between all models prediction and the experimental measurements, but within the lateral channel, the
RSM predictions were in better agreement with the measured data, and k-ω predictions was better than
those of k-ε. The comparison of experimental and numerical streamlines at different elevations
showed that the selected model is capable to simulate the most important features of flow at
diversions. The study of the velocity contours at different elevations showed that the velocity
magnitude decreases at main channel, just downstream corner of lateral intake at the near bed levels
and this causes the sedimentation in movable beds. The results showed that the width of separation
zone at lateral intake will decrease and the distance of dividing stream surface from left bank of the
main channel will increase by increasing of the discharge ratio. Investigation of the flow pattern at the
entrance of the lateral intake showed that the secondary flow will form at this section. The dimension
of the secondary flow at near bed elevation will increase by increasing of the discharge ratio and this
causes entering of more bed load into the lateral channel.
Volume 15, Issue 2 (7-2015)
Abstract
Computational Fluid Dynamics (CFD) implementations are also classified as the Lagrangian and Eulerian methods. Smoothed Particle Hydrodynamics (SPH) is a mesh free particle method based on Lagrangian formulation with a number of advantages. This method is obtained approximate numerical solutions of the equations of the fluid dynamics by replacing the fluid with a set of particles. All particles carry their properties and then the advection is taken care automatically. In contrast, Eulerian mesh based numerical methods have difficulties such as the problem of numerical diffusion due to advection terms. Because of the simplicity and robustness of SPH, this numerical method has been extended to complex fluid and solid mechanics problems. The important advantage of SPH is that the muli-phase flows can be modeled by SPH and each particle can be assigned to a different phase. In this paper, the SPH method is used for simulating water and sediment flow in dam break problem. The government equations are momentum and continuity equations which are described in a Lagrangian framework. Also, the compressible flows are modeled as a weakly compressible flow via the equation of state. The XSPH equation is applied for each particle movement at each time step. The Wendland kernel is applied as smoothing function. Sediments are treated as non-Newtonian fluid and for simulating them the non-Newtonian models are used. In this paper, the combination of two rheological models named Bingham and Cross is used. The predictor- corrector algorithm is applied. The time step is controlled by Courant condition (CFL), the forcing terms and the viscous diffusion terms. On the other hand, the laboratory experiment of dam break is performed and the new experimental set up was built. At first, the column of water with a height of 0.5 m and the wide of 0.25 m is blocked by a partition gate. The bottom of the water column is covered with non cohesive sediments. The sediments are sands with d50=1.4 mm. The partition gate separates the water column from the downstream channel and the speed of partition gate is more important. Then the partition gate is removed with a specific velocity. The partition gate opens completely from above with a constant speed of 0.6 m/s. The flow motion is recorded by digital camera system. Finally, a comparison between experimental results and computational results is carried out and the errors are calculated. The error of sediment height variations in specific horizontal distances (x=5 cm and 14 cm) in reservoir are 6.55% and 5.94%, respectively. Also, the sediment surface profiles are shown in different times. The comparisons are shown good agreements between numerical and experimental results. The good agreement proves the ability of the present SPH model to simulating two phase flows.
Volume 17, Issue 1 (5-2017)
Abstract
Side weir is one of the most important structures in flood treatment projects that are designed provided the main channel bed is rigid. However, in the most practical channels, the main channel bed is movable and the changes in bed can produce wavelike patterns known as bed forms and another additional effect of side weir on bed forms is that it causes an aggradation of sediment particles in front of itself. These two products of using side weir in movable beds cause an additional bed resistance in comparison with the state that there isn’t any weir on sidewall of main channel and so the flow level with using side weir will rise subsequently and this means more diversion ratio. Thus, In order to study the effect of side weir hydraulic and geometric properties through Froude Numbers, diversion discharge ratios and flow depths on bed forms and its effect on design conditions, the present research work is carried out. A set of 9 experiments were conducted in a flume with dimensions of 0.85 m width, 0.40 m height and 10 m length on a mobile bed having median sediment particle size of 0.23 mm running with side weirs of crest lengths of 20, 40 and 60 cm . In addition a set of 3 experiments without using a weir were considered as bench mark experiments for comparison purposes. After running a determined flow in flume regarding with the bed profiles should reach a balance it was stopped after 1-3 hours. The bed topography at the end of each experimental run was recorded using automatic bed profiler in a length of 220 cm of main channel. This topography was recorded in a net of points that were distributed in a distance of 5 cm in length and 3 cm in width. The dimensions of bed forms were then determined using the well-known crest-through method. The results indicated that the effect of flow depth, discharge, and diversion ratio on bed form dimensions are significant and increasing these parameters cause an increasing influence on bed form dimensions. In this study 4 equations are suggested that both of them are for bench mark experiments and two others are for main experiment. The coefficients of these relations were determined by Solver Add In program in Excel with using 80 percent of data that were selected in chance and then they were verified with using remaining 20 percent of data. Verification of relations also illustrated that for both length and width of bed form in main experiments the maximum error of related equations is 50 percent and maximum error of relations for bench mark experiments is 30 percent. Analyzing these relations revealed an important influence of applying side weirs on lateral variation of bed form dimensions in the main channel so that it is indicated that bed form length and height near side weir will increase up to 70 and 2 percent of channel width, respectively, in comparison with the experiments that side weir is not used.
Volume 19, Issue 4 (11-2019)
Abstract
An important goal of deviation of water flowing in a river is to control sediment and supply required water with minor sediment. This goal can be achieved using some sediment control structures, such as sill, spur dike and submerged vanes. These structures, however, can influence the flow pattern in a water intake, which induces scouring at downstream of the intake in main channel. For instance, generated helical motion due to secondary circulation induced by submerged vanes is the main cause of scouring at downstream of these structure. As for spur dikes, the generated helical motion is also the main cause of scouring in the main channel downstream, which occurs through increased flow velocity and curvilinear flow near the spur dikes. The induced scouring may impact the stability of coastal region near the channel/river that must be taken into account in designing process. In this study some experimental tests were carried out to understand the effect of sill, spur dike and submerged vanes on sediment control and scouring in the downstream of intake in the main channel. Four different cases were considered to be discussed; in the first case, there was no sediment control structure installed. In the second one, however, the effects of a sill with a height of one third of the flow depth at the entrance of the intake was evaluated. In the third case the effect of installing both sill and spur was studied. In this case, in addition to a sill installed at the intake entrance, an impermeable direct non-submerged spur, with a length of 1/4 of width of the main channel at upstream, was mounted on the opposite side of the intake at upstream of the main channel. In the fourth case, submerged vanes were added up to the two other mentioned structures earlier. The submerged vanes were put in two parallel rows in front of the intake in the main channel. All experimental tests were conducted in a flume equipped with a recirculating sediment system and a 90° lateral diversion channel. Three important parameters including the ratio of bed sediment transport into intake (Gr), the volume fraction of sediment deposited within intake (Vr), and the dimensions/volume/area of scouring at upstream in the main channel were evaluated in this study under three different discharge ratios of 0.12, 0.15 and 0.18. The experimental results indicate that the mentioned parameters are mainly determined by the discharge ratio and the mechanism of sedimentation control. It can be noted that Gr increases with Qr, whereas Vr decreases as Qr raises up. It was also observed that all sediment control structures play an important role in sediment control at the intake entrance, although the influence of spur dike and submerged vanes is greater as compared with that of sill, which causes a significant reduction in Gr and Vr. It was also found that the dimensions/volume/area of scouring area at upstream in the main channel is mainly controlled by existence of those structures. Generally speaking, the dimensions/volume/area of scouring area is mainly controlled by the velocity of water in contact with the downstream bank of intake, Qr, the power of induced secondary flow by the submerged vanes and the spur dike, and the cumulative sediment in front of the intake due to existence of sill. It was also noticed that in some cases both the submerged vanes and the spur dike may result in scour increase. The dimensions/volume/area of scouring area demonstrated different behavior over different Qr ranges that could be described through this fact that these parameters are influenced by many causes simultaneously. To approximate Gr, Vr and dimensions/volume/area of scouring area in different situations, some relationships have been presented in this study. A comparison has also been made between the results obtained from the current study and those presented by other authors, based on which the most proper structure was chosen with respect to sediment control and scouring. Eventually, the third and fourth cases were found as the most desirable system able to control sediment more efficiently comparing to other cases.
Volume 21, Issue 7 (Supplementury Issue 2019)
Abstract
Biomass is an important parameter in studying a variety of energetic processes in food webs, community structure, and composition of aquatic organisms. Biomass determinations are based on direct weighing of animals, biovolume determination, and length-weight conversion. Although direct weighing of individual organisms is the most accurate methodology, its application is not very common due to its time consuming nature. Length-weight regressions are the most widely used approach for estimating benthic invertebrate biomass because they are less time consuming and more precise than other methods. In this research, length-weight relationships are evaluated for the most common benthic invertebrates found in an Iranian mountain river in the Southern Caspian Sea Basin by fitting the power function (linearized by logarithmic transformation) to data of wet and dry weights against body length of aquatic invertebrates at both family and order level. A general predictive equation was also obtained for all individuals measured in this study. Regressions obtained were significant at a P value of < 0.05 and explained a high proportion of variation of the dependent variable, as expressed by the correlation coefficient (r= 0.82-0.99). Regression equations obtained in this study for three major orders of aquatic invertebrates were also compared to those in previous studies from different geographical locations. Relationships developed in this study, can be useful for future assessments of benthic community structure and for understanding the importance of these invertebrates in the energy flux of the river.
Volume 23, Issue 3 (5-2021)
Abstract
This experiment was conducted in order to determine the hydrodynamic performance of a Triangular Winged Bandal-Like (TWBL) structure, which is a combination of the Bandal-Like (BL) structure and Triangular Vane (TV). For the purposes of this study, the JFE ALEC magnetic velocity meter was used to measure the three components of flow velocity under non-submerged hydraulic conditions at a Froude number of 0.24. The three considered cases for this measurement were the non-structured case and the BL and TWBLs. The results showed that the flow deviation occurred through the impermeable upper part of both structures towards the middle of the channel. At downstream of both structures, bubbling flows were caused by the collision of upward flows with the near-surface flow, causing disturbances in the latter. Both the BL and the TWBL structure reduced the secondary flow strength along the bend within the structure range. Compared to the BL structure, the TWBL structure reduced the secondary flow strength by about 20%, which indicates the weaker inclination of the secondary flow toward the outer bank in the TWBL structure. The relative maximum shear stress in the TWBL structure is on average 17% lower than that of the BL structure.