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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Computational and Applied Research in Mechanical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Simulation,Flow,Turbulence model,Engine,Nonlinear k-ε
- چکیده:
- چکیده انگلیسی: The purpose of this paper is to studying nonlinear k-ε turbulence models and its advantages in internal combustion engines, since the standard k-ε model is incapable of representing the anisotropy of turbulence intensities and fails to express the Reynolds stresses adequately in rotating flows. Therefore, this model is not only incapable of expressing the anisotropy of turbulence in an engine cylinder, but also is unable to provide good performance when computing the swirling and tumbling flows is important in engine cylinders. Thus, in this paper, the results of nonlinear k-ε model are compared with those of the linear one. Results of diesel engine simulation with linear and nonlinear k-ε models in comparison show that turbulence intensity in the nonlinear model simulation is higher than that of the linear model; also, nonlinear k-ε models predict the second peak value because of the bowl shape in expansion stroke for turbulence intensity. Gas injection results show that nonlinear turbulence models predict spray penetration accurately because of correctly turbulence intensities predicting. Also, the results demonstrate that, for high pressure gas injection, turbulence intensity is high and predicted accurately using nonlinear models. Then, its spray penetration length is predicted accurately in comparison to experimental data’s. Although CPU time spending in the nonlinear model is more than that of the linear one, the non-linear stress model is found to increase computation time by 19%.
- انتشار مقاله: 29-10-1393
- نویسندگان: A. A. Mirmohammadi,F. Ommi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Chemical Health Risks
- نوع مقاله: Journal Article
- کلمات کلیدی: nanoparticle,Gelatin Film,Antimicrobial properties,WVP,Oxygen permeability
- چکیده:
- چکیده انگلیسی: The effects of nano titanium dioxide incorporation were investigated on the water vaporpermeability, oxygen permeability, and antimicrobial properties of bovine gelatin films. The nano TiO2 (TiO2-N) was homogenized by sonication and incorporated into bovine gelatin solutions at different concentrations(e.g. 1, 2, 3, and 5% w/w of dried gelatin). The permeability of the films to water vapor and oxygen wassignificantly decreased by incorporating of low concentration TiO2-N to gelatin solutions. TiO2-N gelatin filmsshowed an excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. Theseproperties suggest that TiO2-N has the potential as filler in gelatin-based films for using as an active packagingmaterials in pharmaceutical and food packaging industries.
- انتشار مقاله: 16-09-1392
- نویسندگان: R. Nassiri,A. MohammadiNafchi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Chemical Health Risks
- نوع مقاله: Journal Article
- کلمات کلیدی: starch film mungbean,Rosemary Extract,barrier properties,Colorimetery
- چکیده:
- چکیده انگلیسی: Barrier properties are one of the most important factors in the edible film. In this study, edible mungbean films were prepared containing (0%, 15%, 30%, 45%) concentrations of rosemary aqueous extract. Then the effect of rosemary was investigated on colorimetric and barrier properties (water vapor permeability, oxygen permeability). Rosemary extract increased the absorption of color in the visible region, which in turn led to increase of the parameters a (index color tends toward green) and b (index color tends towards yellow). The results showed that increasing concentrations of rosemary extract have a significant effect( p <0.05) to reduce the amount of oxygen and water vapor permeability. Â Also turbidity of mungbean starch was increased with increasing concentrations of rosemary in the film. Improving barrier properties and the colorimetric properties were showed by rosemary extract compounds that these materials can use as the safety of food and pharmaceutical packaging industry.
- انتشار مقاله: 20-07-1392
- نویسندگان: H. Safari Maznabi,A. Reza MohammadiNafchi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Chemical Health Risks
- نوع مقاله: Journal Article
- کلمات کلیدی: Mechanical properties,SiO2 Nanoparticle,Starch film,Bionanocomposite
- چکیده:
- چکیده انگلیسی: In this paper effect of SiO2 nanoparticles was investigated on potato starch films. Potato starch films were prepared by casting method with addition of nano-silicon dioxide and a mixture of sorbitol/glycerol (weight ratio of 3 to 1) as plasticizers. SiO2 nanoparticles incorporated to the potato starch films at different concentrations 0, 1, 2, 3, and 5% of total solid, and the films were dried under controlled conditions. Â Physicochemical properties such as water absorption capacity (WAC), water vapor permeability (WVP) and mechanical properties of the films were measured. Results show that by increasing the concentration of silicon dioxide nanoparticles, mechanical properties of films can be improved. Also incorporation of silicon dioxide nanoparticles in the structure of biopolymer decrease permeability of the gaseous molecules such as water vapor. In summary, addition of silicon dioxide nanoparticles improves functional properties of potato starch films and these bio Nano composites can be used in food packaging.
- انتشار مقاله: 28-05-1392
- نویسندگان: Z. Torabi,A. MohammadiNafchi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Chemical Health Risks
- نوع مقاله: Journal Article
- کلمات کلیدی: Physicochemical properties,Antimicrobial properties,Biodegradable film,ZnOnanorods
- چکیده:
- چکیده انگلیسی: : Nowadays tend to use biodegradable packaging; including edible coatings and films for free from synthetic chemicals and do not cause environmental pollution, the industry is growing day by day. The aim of this research was to preparation and characterization of biodegradable films supported with ZnOnanorods. In this study, sago starch based films were prepared and  plasticized with sorbitol/ glycerol by casting method. ZnOnanorod with 0, 1, 3and 5%(w/w)was added to the films before casting the films. Films were dried at controlled conditions. Physicochemical properties such as water absorption capacity (WAC), permeability to water vapor (WVP) and water solubility of the films were measured. Also, the effects of addition of nano particles were measured on the antimicrobial properties of the films by agar diffusion method. Results showed that by increasing concentration of ZnOnanorod, solubility in water, WAC, and WVP of the films significantly (p <0.05) decreased. Furthermore, the addition of zinc oxide nanorods showed antimicrobial properties against E. Coli. In summary sago starch films supported with ZnOnanorodscan were used as active packaging for agricultural products as well as food industry.Â
- انتشار مقاله: 09-11-1391
- نویسندگان: R. Alebooyeh,A. MohammadiNafchi,M. Jokr
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Aerospace Science and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Bifurcation,Poincaré map,Preload,Tow-lobe bearing
- چکیده:
- چکیده انگلیسی: This paper presents the effect of preload on nonlinear dynamic behavior of a rigid rotor supported by two-lobe aerodynamic noncircular journal bearing. A finite element method is employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in the horizontal and vertical directions under different operating conditions, the dynamic trajectory, the power spectra, the Poincare maps and the bifurcation diagrams are used. From this study, results show how the complex dynamic behavior of this type of system comprising periodic, -periodic and quasi-periodic responses of the rotor center varies with changes in preload values by considering two bearing aspect ratio. The results of this study contribute to a better understanding of the nonlinear dynamics of two-lobe aerodynamic noncircular journal bearing system.
- انتشار مقاله: 29-01-1389
- نویسندگان: R. Rashidi,A. Karami Mohammadi Karami Mohammadi,F. Bakhtiari Nejad Bakhtiari Nejad
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Aerospace Science and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Bifurcation,Poincaré map,Preload,Tow-lobe bearing
- چکیده:
- چکیده انگلیسی: This paper presents the effect of preload on nonlinear dynamic behavior of a rigid rotor supported by two-lobe aerodynamic noncircular journal bearing. A finite element method is employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in the horizontal and vertical directions under different operating conditions, the dynamic trajectory, the power spectra, the Poincare maps and the bifurcation diagrams are used. From this study, results show how the complex dynamic behavior of this type of system comprising periodic, -periodic and quasi-periodic responses of the rotor center varies with changes in preload values by considering two bearing aspect ratio. The results of this study contribute to a better understanding of the nonlinear dynamics of two-lobe aerodynamic noncircular journal bearing system.
- انتشار مقاله: 29-01-1389
- نویسندگان: R. Rashidi,A. Karami Mohammadi Karami Mohammadi,F. Bakhtiari Nejad Bakhtiari Nejad
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Applied Dynamic Systems and Control
- نوع مقاله: Journal Article
- کلمات کلیدی: Simulation,Boiling,Critical Heat Flux,Two-phase flow
- چکیده:
- چکیده انگلیسی: Heat transfer occurs in flow boiling; as a result, the amount of heat between the tube wall surface and the fluid at different points of the tube may vary depending on the volume percent of vapor at those points. If the flow is fully vaporized, it does not allow for perfect heat transfer at that point; this significantly increases the temperature there; in this case the applied heat flux is called critical heat flux (CHF). The present paper has focused its attentions on simulating a two-phase fluid flow within the CHF range using ANSYS Fluent. The simulation results indicated an average error below 7%, which is more than those obtained by the experimental results. The maximum temperature of the tube surface when applying CHF could range between 200 and 500 K degrees more than that of fluid saturation according to the fluid working conditions. It also should be noted that both CHF and maximum temperature increase as the input pressure and mass flux do increase.
- انتشار مقاله: 09-12-1397
- نویسندگان: K. Dolati Asl,E. Abedini,Y. Bakhshan,A. Mohammadi Karachi,R. Hamidi Jahromi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Veterinary Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Cattle,Phylogenetic analysis,Bovine viral diarrhea virus,molecular characterization
- چکیده: ویروس اسهال ویروسی گاو (BVDV) یکی از مهمترین عوامل بیماریزای ویروسی گاو در جهان به شمار میرود. هدف از مطالعه حاضر تعیین خصوصیات مولکولی و آنالیز، فیلوژنتیک عفونت BVDV در تعدادی از گاوهای استان فارس، ایران میباشد. به همین منظور در پایش اولیه، تعداد 400 نمونه خون از 12 گاوداری صنعتی با سابقه اسهال، سقط جنین یا تولد گوسالههای ضعیف جمعآوری و به روش RT-PCR مورد آنالیز قرار گرفت. در مرحله بعد، تعداد 100 نمونه خون و بیوپسی بافت گوش از گاوهای آلوده مرحله اول بعد از 3 هفته تهیه گردید و با روشهای ACE، IHC و RT-PCR مورد ارزیابی مقایسهای قرار گرفتند. نتایج آزمایش RT-PCR در پایش اولیه نشان دهنده آلودگی 16 مورد از 400 نمونه مورد آزمایش (4%) بود. همچنین 8 مورد از 100 نمونه مرحله بعدی به وسیله همه روشهای تشخیص به صورت یکسان مثبت (8%) تشخیص داده شد. واکنش ایمنی به آنتی ژن BVDV به صورت رنگ قهوهای گرانولر در سیتوپلاسم سلولهای پوششی اپیدرم، فولیکولهای مو و سلولهای استرومایی زیر جلدی مشاهده گردید. آنالیز توالی ژنتیک، هر دو ژنوتیپ BVDV-1 و BVDV-2 را نشان داد که در ترسیم درخت فیلوژنی به نامهای BVDV1-FarsA، BVDV1-FarsB و BVDV2-FarsA معرفی گردید. در مجموع بر اساس نتایج این مطالعه با توجه به حضور هر دو ژنوتیپ ویروس در گاوهای منطقه، اهمیت تشخیص و حذف گاوهای دارای عفونت مزمن و پایدار برای کنترل و ریشهکنی بیماری در استان فارس مورد تأکید قرار میگیرد.
- چکیده انگلیسی: Bovine viral diarrhea virus (BVDV) is one of the most important viral pathogens of cattle worldwide. The aim of present study was to determine the molecular characterization and phylogenetic analysis of BVDV infection in dairy herds of Fars province, Iran. For initial screening, a total of 400 blood samples were collected from 12 industrial dairy herds with previous history of diarrhea, abortion or birth of weak calves and analyzed using reverse transcription-polymerase chain reaction (RT-PCR) on buffy coat. In the next step, blood samples and also ear notch biopsies were collected from 100 cattle of infected farms three weeks later which were subsequently tested by antigen capture ELISA (ACE), RT-PCR and immunohistochemistry (IHC). The results of nested RT-PCR were successful in 16 out of 400 buffy coat samples (4%) in the initial screening. Also, 8 out of 100 samples (8%) were positive by all practiced tests including RT-PCR, ACE and IHC on buffy coat, serum and skin samples, respectively. Immunoreactivity for bovine BVDV antigen as brown, coarsely to finely granular was observed within the cytoplasm of epidermic epithelial cells, hair follicles and subcutaneous stromal cells. Genetic sequence analyses showed both genotypes, BVDV-1 and BVDV-2. The new isolates were identified as BVDV1-FarsA, BVDV1-FarsB and BVDV2-FarsA in the phylogenetic tree. Since both genotypes of the virus are present in the region, our findings emphasize the importance of monitoring BVDV infection in cattle and suggest detection and elimination of PI animals for controlling and eradication of BVDV in Fars province.
- انتشار مقاله: 07-07-1394
- نویسندگان: A. Khodakaram-Tafti,A. Mohammadi,GH. Farjani Kish
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Veterinary Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Chicken,H9N2 avian influenza virus,Quantitative real-time PCR,Echinacea purpurea,Sambucus nigra
- چکیده: مطالعات پیشین نشانگر اثر ضد ویروسی فراوردههای گیاهی سرخارگل و آقطی سیاه بر ویروسهای آنفلوانزای انسانی در شرایط in vitro میباشد. برای بررسی اثر ضد ویروسی عصاره این گیاهان دارویی در شرایط طبیعی، از دو عصاره استاندارد شده سرخارگل (EF) و آقطی سیاه (SAM) و داروی آمانتادین در جوجههای گوشتی آلوده شده به ویروس آنفلوانزای پرندگان تحت تیپ H9N2 استفاده شد. 8 ساعت پس از تلقیح ویروس EF و SAM و داروی آمانتادین، و به مدت 7 روز به آب آشامیدنی جوجهها اضافه شد.گروه پروفیلاکسی از 5 روز پیش از چالش و به مدت ده روز، EF در آب آشامیدنی دریافت نمود. در طی روزهای پس از چالش میزان تیتر ویروس در نمونههای مخاط نای و مدفوع جوجهها با استفاده از آزمون واکنش زنجیرهای پلیمراز زمان حقیقی اندازهگیری شد. نتایج نشانگر بالاترین مقادیر دفع ویروس از مدفوع و نای در گروه کنترل چالش (بدون درمان) در روز 3 پس از چالش میباشد. در مقایسه با گروه چالش بدون درمان، تیتر ویروس نمونههای مدفوع گروه پروفیلاکسی EF در تمام روزهای پس از چالش به میزان قابل توجهی کمتر بود. همچنین، همگی نمونههای مدفوع پرندگان هر دو گروه درمان و پروفیلاکسی EF در روز 3 پس از چالش بر خلاف سایر گروههای چالش از نظر دفع ویروس منفی بودند. اگر چه به طور کلی تیتر ویروس در نمونههای نای کم بود، درمان با SAM و آمانتادین سبب کاهش موارد نمونههای مثبت در مقایسه با گروه کنترل مثبت و درمان یا پروفیلاکسی با EF گردید. این مطالعه بر کاهش دفع ویروس آنفلوانزا در نمونههای مدفوع و نای پس از استفاده عصاره الکلی سرخارگل و عصاره آبی آقطی سیاه در جوجههای گوشتی دلالت مینماید.
- چکیده انگلیسی: Previous studies have shown antiviral effect of Echinacea and elderberry preparations against human influenza viruses in vitro. To investigate the in vivo antiviral effect of these herbs on avian H9N2 influenza virus, amantadine and two standardized commercial extracts of Echinacea purpurea (EF) and Sambucus nigra (SAM) were used in broiler chickens infected with H9N2 strain of the virus. EF, SAM and amantadine were added to drinking water of chickens in different groups for 7 days starting 8 h after intranasal inoculation of the challenged virus and in prophylaxis group of EF for 10 days starting 5 days before the challenge time. During post infection (PI) days, titer of the virus in tracheal mucosa and faeces were quantified using quantitative real-time PCR. The untreated challenged group showed the highest faecal and tracheal titer of the virus on day 3 PI. The virus was not detected in negative control group during the course of the experiment. Prophylaxis administration of EF considerably reduced the faecal titer of the virus in all
days PI. Although overall titer of the virus in the tracheal samples was low, treatment with amantadine and SAM apparently reduced quantity of tracheal positive samples in comparison to untreated and EF-treated groups. This study indicates that using Echinacea and elderberry extracts in chicken can reduce H9N2 virus shedding from trachea and faeces.- انتشار مقاله: 04-04-1392
- نویسندگان: S. Karimi,H. Dadras,A. Mohammadi
- مشاهده