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In this article, the calm water resistance and dynamic instabilities of a semi-displacement catamaran fitted with a stern wedge is investigated using an experimental method and numerical technique. This is accomplished in order to probe into the effects of aft geometry modification on semi-displacement ship dynamic characteristics, especially at medium and high speeds. An advanced 6-DOF model that takes into consideration the dynamic mesh method has been utilized in open source code OpenFOAM. Reynolds-Average Navier-Stokes (RANS) equations are solved using standard k-ε turbulence model and VOF method. The accuracy of the current numerical method is investigated by the calm water test in National Persian Gulf Towing Tank. The resistance, trim and sinkage of the ship were monitored during the experiments. The experimental analysis was performed on the initial model and a modified model with 8º wedge at different Froude numbers. After that, the wedges were mounted at different angles at the transom of the vessel and the effect of the angle change for 4 different angles was evaluated using numerical solution. The results show that fitting a stern wedge to this type of ship causes an intense pressure at the stern bottom. Also, it decreases the dynamic trimming and forward resistance of the craft. As well as, stern wedge causes increasing the lift force which affects the reduction of dynamic instabilities. It is concluded that numerical model presented here is quite suitable for accurately predicting dynamic characteristics of a semi-planing twin-hull ships at medium and high Froude numbers. As a result, 14% reduction in total resistance was observed due to the installation of a 6 degree stern wedge.

Purpose Pediatric Emergency Care Applied Research Network (PECARN) traumatic brain injury (TBI) prognostic rules is a scoring system for prediction of the need for computed tomography (CT) scanning in children with mild TBI. However, its validation has not been assessed in developing countries. Therefore, the present study was designed to assess the value of PECARN rule in identification of children with clinically important TBI (ciTBI). Method In this prospective cross-sectional study, 594 children (mean age: 7.9 ± 5.3 years; 79.3% boys) with mild TBI brought to emergency ward of two healthcare centers in Tehran, Iran were assessed. PECARN checklist was filled for all patients and children were divided to three groups of low, intermediate and high risks. Patients were followed for 2 weeks by phone to assess their ciTBI status. At the end, discrimination power, calibration and overall performance of PECARN rule were assessed. Results PECARN had a sensitivity and specificity of 92.3 and 40.6%, respectively, in predicting ciTBI in children under 2 years and 100.0 and 57.8%, respectively, in individuals between the ages of 2 and 18. PECARN rule had a proper calibration in prediction of ciTBI and CT scan findings. Brier score (overall performance) of PECARN rule in predicting ciTBI in children under 2 and 2–18 years were 1.5 and 1.2, respectively. Conclusion PECARN prediction rule has a proper validity in the prediction of ciTBI. Therefor it can be used for screening and identification of high risk children with mild TBI.

In the current study, a 3-D numerical simulation of two-phase flow has been conducted in a direct injection CI engine using the Eularian-Lagrangian approach and a new breakup model. The newly modified breakup scheme has been implemented for simulating the ultra-high pressure diesel injection. The effects of droplet breakup and collision model on the spray and in-cylinder gas characteristics have been examined using the open source code OpenFOAM. Spray penetration and cone angle are investigated as spray properties and surrounding gas motion are studied by in-cylinder gas velocity and pressure distribution for non-evaporating conditions. In addition, vapor penetration of the evaporating spray is presented to study the effects of current scheme on the evaporating condition. The continuous field is described by RANS equations and dynamics of the dispersed droplet is modeled by Lagrangian tracking scheme. Results of the proposed modified KHRT model are compared against other default methods in OpenFOAM and favorable agreement is achieved. Robustness and accuracy of different breakup schemes and collision models are also verified using the published experimental data. It is demonstrated that the proposed breakup scheme and Nordin collision model display very accurate results in the case of ultra-high pressure injection.

Advanced models of spray breakup and droplet collision are implemented in OpenFOAM code for comparing the flat-wall impinging and free fuel sprays under ultra-high pressure direct injection diesel engines. The non-evaporating spray and ambient gas flow characteristics are analyzed by a combination of Eulerian and Lagrangian methods for continuous and dispersed phase, respectively. Various injection pressures and two different impinging distances are used. Reynolds Averaged Navier Stokes (RANS) equations are solved using standard k-ε turbulence model. Computational domain and grid size are determined based on a mesh study. Numerical results are validated by published experimental data for free and wall-impinging sprays. The robustness and accuracy of the proposed scheme are confirmed by comparing the main characteristics of spray and surrounding gas against published experimental data. To accomplish this, spray shape, penetration and gas velocity vectors are compared with experimental data and insightful understanding of the spray characteristics are provided. In comparison with free spray, tip penetration has been limited in impinging sprays. Turbulent flow in impinging sprays leads to more induced air motion. Also, impinging spray leads to more pushed-out gas velocity. The obtained results indicate that the numerical findings are generally in good agreement with experimental data in case of ultra-high injection pressures and micro-hole injectors.

In the current study, effect of chamber ambient backpressures and temperatures on non-reacting fuel spray characteristics of heavy fuel oil (HFO) under high pressure injection is numerically studied. Four different chamber backpressures ranging from 0.05 up to 2.8 MPa at two different ambient temperatures have been considered in a medium speed engine. An Eulerian-Lagrangian multiphase scheme is implemented to model HFO interaction with air continuous phase by using Open source CFD toolbox of OpenFOAM. Numerical results of fuel spray are validated with good accordance against existing experimental data. Based on the computational findings, enhancement of chamber backpressure results in reduction of temporal spray penetration and increase of spray cone angle at both ambient temperatures. Furthermore, the SMD is found to decrease due to enhancement of chamber backpressures up to 1.4 MPa. Finally, it was found that higher ambient temperature increases the spray penetration length at all chamber backpressures.

Crosses were made between two Populus species to create two hybrid groups, P. alba ♀ * P. euphratica ♂ and P. euphratica ♀ * P. alba ♂. Aseptic immature hybrid seeds were first grown on MS medium. Hybrid seedlings were then acclimatized and grown in greenhouse conditions and transplanted to an experimental field. Growth related characteristics were recorded on 307 three years-old seedlings of new inter-specific hybrids of six half-sib families, in order to assess possible potentials of the two hybrid groups. Double nested analysis of variance revealed significant differences between the hybrid groups and siblings based on majority of the studied characters. The hybrid groups formed two distinct groups for some of the studied characteristics which implied maternal effects of inheritance on the traits. The first hybrid group had more but shorter and closer branches than the second group. Adaxial stomata number for the two hybrid groups varied between 4.7 to 123. Whereas, there were no such strong differences between vegetative characteristics of the two groups. The second hybrid group had a very condense layer of white fuzz on its abaxial leaf surface, inherited from its female parents. This may lead to suggest some kinds of photosynthesis and respiration functions such as leaf sub-stomatal chambers’ functions for the mentioned fuzzy trichomes of the second hybrid group and their female parental species, P. alba. In essence, 307 new divergent poplar hybrid genotypes were produced by which ecological zone of poplar species could be extended in the country as well as high yielding genotypes would be promising.

The obesity and hypertension are the major risk factors of several life threatening diseases. The present study was aimed to investigate the relation between body mass index (BMI) the validated index of adiposity and different aspect of blood pressure (BP). Systolic and diastolic blood pressures and also weight and height of 7 to 18 years old children and adolescent collected in 2002 and 2004 respectively. Data was consisted of 14865 schoolchildren and adolescents from representative sample of country. BMI was classified according to CDC 2000 standards into normal (BMI<85th percentile), at risk of overweight (BMI≥85th and <95th percentile) and overweight (BMI≥95th percentile). Then, age-sex specific prevalence of being overweight was derived. ANOVA was used to investigate the effect of BMI on systolic blood pressure and diastolic blood pressure and mean arterial pressure of participants. Mean systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP) significantly increased with BMI (P< 0.0001) and age groups (P< 0.0001), and was significantly (P< 0.0001) higher in boys than girls especially in older ages. (P< 0.0001, interaction of age and BMI level). The proportion of being overweight was significantly higher in boys than girls was (7.4% vs. 3.6%; P< 0.0001). There is an association between BP and BMI in children and adolescence. SBP, DBP and MAP are associated with rise in BMI and age, which was lower in girls. This data can provide basics for public health policy makers and primary prevention policies in the country.

Background: Lung cancer is the leading cause of cancer-related death worldwide, and half of all incident lung cancers are believed to occur in the developing countries, including Iran. Objective: We investigated the association of opium with the risk of lung cancer in a case-control study. Methods: We enrolled 242 cases and 484 matched controls in this study. A questionnaire was developed, containing questions on basic demographic characteristics, as well as lifelong history of smoking cigarettes, exposure to passive smoking, opium use and alcohol consumption. For smoking cigarettes and opium and also oral opium intake frequency, duration and cumulative use were categorized into three groups: no use, low use and high use. Conditional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs). Results: Multivariate analysis in men showed that after adjusting for the effect of ethnicity, education and pack years of smoking cigarettes, smoking opium remained as a significant independent risk factor with an OR of 3.1 (95% CI 1.2–8.1). In addition, concomitant heavy smoking of cigarettes and opium dramatically increased the risk of lung cancer to an OR of 35.0 (95% CI 11.4–107.9). Conclusion: This study demonstrated that smoking opium is associated with a high risk of lung cancer as an independent risk factor.

In the current study, effect of chamber ambient backpressures and temperatures on non-reacting fuel spray characteristics of heavy fuel oil (HFO) under high pressure injection is numerically studied. Four different chamber backpressures ranging from 0.05 up to 2.8 MPa at two different ambient temperatures have been considered in a medium speed engine. An Eulerian-Lagrangian multiphase scheme is implemented to model HFO interaction with air continuous phase by using Open source CFD toolbox of OpenFOAM. Numerical results of fuel spray are validated with good accordance against existing experimental data. Based on the computational findings, enhancement of chamber backpressure results in reduction of temporal spray penetration and increase of spray cone angle at both ambient temperatures. Furthermore, the SMD is found to decrease due to enhancement of chamber backpressures up to 1.4 MPa. Finally, it was found that higher ambient temperature increases the spray penetration length at all chamber backpressures. KCI Citation Count: 9

In this article, non-evaporating and non-reacting diesel spray is modeled under ultra-high injection pressure using an Eulerian-Lagrangian scheme. This is accomplished in order to probe into the effects of injection pressure, nozzle diameter, and ambient density on spray characteristics. An advanced hybrid breakup model that takes into consideration the transient processes during spray injection has been added to the open source code, OpenFOAM. Reynolds-Average Navier-Stokes (RANS) equations are solved using the standard k - ε turbulence model and the fuel droplet is tracked by a Lagrangian scheme. Published experimental data have been used for validation of spray characteristics at 15 kg/m^sup 3^ ambient density and injection pressures of 100, 200 and 300 MPa. Also, three nozzle diameters of 0.08, 0.12 and 0.16 mm have been implemented for investigating the effect of this parameter on spray formation. Computed spray shape, jet penetration, spray volume, equivalent ratio along the injector axis and Sauter Mean Diameter (SMD) illustrate good agreement with experimental data of a single hole nozzle and symmetric spray. The effects of fuel injection pressure, nozzle hole diameter and ambient density on main spray parameters are presented. It is concluded that the numerical model presented here is quite suitable for accurately predicting diesel spray shapes under ultra-high injection pressures.