javad. alinejad

In the present study, the effect of the heating pipe profile on natural convection in a two-phase fluid inside a cavity has been investigated. This geometry has been simulated with the LB Method based on the D2Q9 model for analyzing stream lines, dimensionless velocity field of fluid flow, solid particles volume fraction, temperature arrangement, and Nusselt number. These parameters have been studied in three different cases of the cavity. The results are signified by changing the geometry from a horizontal ellipse to a circular one and a vertical ellipse;the maximum particle volume fraction is decreased. Also, by changing the geometry from a horizontal ellipse to a circular and vertical ellipse, larger velocity vectors have been formed around the geometry. The Nusselt number variations of circular and  vertical ellipse geometries are from 90⁰ to 270⁰. The Nusselt number variation of horizontal ellipse geometry is negligible from 90⁰ to 270⁰.  Also, the Nusselt number of the circular geometry is larger than the other geometries from 270⁰ to 90⁰. The highest average Nusselt number belongs to circular, vertical and horizontal ellipse geometries, respectively.

Droplet based microfluidic systems have found versatile industrial and scientific applications, like biological engineering, lab-on-chip, drug delivery, and encapsulation. In the current study, the breakup of mother droplets in a symmetric Y-junction microchannel under an electric field is numerically investigated. To this approach, a 2D numerical model base on the level set method is performed by the COMSOL Multi-physics software. Two methods for applying the electric field are considered: a symmetric and an asymmetric electric field. In the symmetric electric field, it is observed that the mother droplet splits faster in the presence of an electric field when compared with the case without the electric field. Also, the mother droplet is divided into two daughter droplets with equal sizes. For the asymmetric electric field, the results reveal that the mother droplet splits into two daughter droplets with unequal sizes. Furthermore, a novel flow pattern called hybrid pattern is determined in the asymmetric splitting of droplets. In addition, there is a critical electric capillary number above which a non-splitting pattern.

This study investigated the effects of different arrangements of three-dimensional fibers on polymer matrix composite thermal conductivity under heat flux boundary conditions. The thermal lattice Boltzmann based on the D3Q7 (three dimensions and seven temperature vectors) method is utilized to illustrate the thermal conductivity in 7 cases of PMC with a different arrangement of 3D fibers. Nondimensional temperature fields, isothermals, nondimensional thermal conductivity coefficient, nondimensional mean, and local temperature in 7 cases of PMCs have been investigated. The non-dimensional thermal conductivity coefficient in each PMC has been analyzed to predict optimal levels of factors affecting this simulation to maximize and minimize the heat transfer rate. The results signified that nondimensional temperature field in a PMC with the arrangement of a fiber, triplet, and triangular perpendicular to heat flux had a greater rate than a PMC with the arrangement of fibers along the way heat flux. Also, the Maximum and minimum of nondimensional thermal conductivity coefficient were in PMC with the arrangement of triplet fibers perpendicular to heat flux,  and triangular fibers along the way heat flux, respectively.

Droplet motion in microchannels is observed in versatile industrial and scientific applications, such as biological engineering, drug delivery, and encapsulation. In current investigation, breakup of mother droplet in a T-junction microchannel is simulated using the Gerris open-source software. To validate current simulation, results are appraised by the published literatures. The comparison depicts that the current results are in good agreement with previous studies. The effect of the presence of a semi-circular obstacle on the flow pattern and the breakup time of mother droplet is investigated for different Capillary numbers (0.006 Ca 0.019) and the non-dimensional initial length of droplet (L*=2, 3, and 4). The results reveal that by simple modifications on the symmetry T-junction, the mother droplet splits faster in the comparison of the ordinary symmetry T-junction geometry under the same conditions. For instance, the breakup time of mother droplet at Ca=0.01 for L*=2, 3, and 4 approximately decreases 75%, 45%, and 32% in the presence of obstacle, respectively. Furthermore, the breakup time of the drop decreases by increasing the Capillary number.

This investigation is a three dimensional comprehensive heat transfer analysis for partially differentially heated enclosure with the vertical fin mounted on the hot wall. The thermal lattice Boltzmann based on D3Q19 method is utilized to illustrate the effects of vertical fins and nanoparticles on the flow and thermal fields. The effects of Rayleigh number and different arrangement of fins on the fluid flow and heat transfer have been scrutinized. The streamlines and isotherms and Nusselt number along the hot wall are illustrated for 104<Ra<108 and nanoparticles volume fraction 0.01<φ6 and two fins in Ra =104), the average Nu could be increased by more than 60%, but the effect of using the nanofluids (φ=0.03, Cuo/Water) is less than 30%. So arrangement of fins and nanofluids (φ=0.03, Cuo/Water) effects improve the heat transfer mechanism in the cubical enclosure.

Brucellosis is a major health problem in northeast of Iran. There is not much data on the association of nutrition and lifestyle factors with the risk of brucellosis in this area. We conducted the present study to determine the risk factors of brucellosis in Khorasan-e Razavi Province, northeastern Iran.
we conducted a case-control study from July 2015 to March 2016 in three cities of Khorasan-e Razavi Province. Cases and controls were recruited from individuals attending primary care and were matched together based on their age (± 2 years) and gender. Clinical and epidemiological data were collected with a valid questionnaire. Conditional logistic regression was used in Stata software V13.
We recruited 180 incident cases and 360 controls, of which 53.9% were male, and 90.0% were living in rural areas. Consumption of unpasteurized yogurt (OR): 5.4; 95% CI: 2.5-11.5), milk (OR: 6.0; 95% CI: 3.0-11.9), and cheese (OR = 3.7; 95% CI: 1.7-8.1), as well as engagement in livestock-related occupations (OR: 2.6; 95% CI: 1.2-5.2) significantly increased the adjusted risk of brucellosis. Conversely, having academic education (OR: 0.1; 95% CI: 0.01-0.5), consuming unpasteurized butter (OR: 0.4; 95% CI: 0.2-0.8), and timely animal vaccination (OR: 0.3; 95% CI: 0.1-0.5) had a protective effect on brucellosis.
The risk factors identified in this study are lifestyle- and occupation- related modifiable factors. So, the disease incidence is expected to decrease in this region with modification of these risk factors, such as animal vaccination, personal protection at work, and public health education.