فهرس المقالات Chemical reaction

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  1 - بررسی تغییرات آلاینده ازن در ایستگاه اقدسیه شرکت کنترل کیفیت هوا و پارامترهای هواشناسی طی مدت هفت ماه (مهر 86 تا پایان فروردین 87) در تهران
  منصور غیاث‌الدین لیلا صورتی
  زمینه و هدف: ازن اکسیدکننده بسیار قوی از واکنش های متقابل فتوشیمیایی اکسیدهای نیتروژن و هیدروکربن ها در حضور نور خورشید تولید می شود. در این تحقیق اندازه‌گیری آلاینده ازن در ایستگاه اقدسیه شرکت کنترل کیفیت هوا و پارامترهای هواشناسی ایستگاه رسالت مورد بررسی و مقایسه قرار أکثر

  زمینه و هدف: ازن اکسیدکننده بسیار قوی از واکنش های متقابل فتوشیمیایی اکسیدهای نیتروژن و هیدروکربن ها در حضور نور خورشید تولید می شود. در این تحقیق اندازه‌گیری آلاینده ازن در ایستگاه اقدسیه شرکت کنترل کیفیت هوا و پارامترهای هواشناسی ایستگاه رسالت مورد بررسی و مقایسه قرار گرفت. روش بررسی: در این تحقیق اندازه‌گیری ازن با دستگاه آنالایزر (O3 42 Modeule) در ایستگاه اقدسیه شرکت کنترل کیفیت هوا برای بازده زمانی هفت ماه (مهر 86 تا پایان فروردین 87) انجام یافت. یافته ها: میانگین تغییرات روزانه ازن در طی روز نشان می‌دهد کم ترین مقدار ازن در ساعات اولیه صبح و اواخر شب می‌باشد. مقایسه شدت تشعشع خورشید با غلظت ازن نشان می‌دهد که این دو با هم ارتباط مستقیم دارند، افزایش شدت تشعشع خورشید، باعث افزایش فعالیت فتوشیمیایی و در نتیجه افزایش غلظت ازن می‌شود. بررسی میانگین ازن ماهانه نشان می‌دهد که کم ترین مقدار ازن ثبت شده در طی هفت ماه اندازه‌گیری در آذرماه و بیش ترین مقدار ازن ثبت شده در فروردین ماه رخ داده است. نتیجه گیری: عامل مهم پیک اصلی که در فروردین‌ماه رخ داده است، افزایش شدت تشعشع خورشید و افزایش فعالیت فتوشیمیایی می‌باشد. تفاصيل المقالة
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  2 - MDH Flow Past a Vertical Rotating Plate with Chemical Reaction and Mass Diffusion in the Presence of Hall ‎Current
  Neetu Kanaujia‎ U S Rajput
  In the present paper, MHD flow past a vertical rotating plate with chemical reaction and mass diffusion in the presence of Hall current is studied. The fluid is electrically conducting and the flow is along the plate. The model under consideration is solved by Laplace t أکثر

  In the present paper, MHD flow past a vertical rotating plate with chemical reaction and mass diffusion in the presence of Hall current is studied. The fluid is electrically conducting and the flow is along the plate. The model under consideration is solved by Laplace transform method. This study is useful in magnetic field controlled material processing, planetary systems and MHD energy generators, etc. تفاصيل المقالة
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  3 - Numerical Study of Two Reaction Mechanisms on Delft Flame III Using Large Eddy Simulation and Conditional Moment Closure Approach
  M. Zakyani Roudsari
  10.30495/ijim.2022.59473.1500
  A conditional moment closure model is adopted together with a state-of- the-art LES approach to simulate the target flame of the TNF workshop, Delft piloted methane flame III. For modeling the sub-grid scales, the constant Smagorinky model and the Dynamic Wale model are أکثر

  A conditional moment closure model is adopted together with a state-of- the-art LES approach to simulate the target flame of the TNF workshop, Delft piloted methane flame III. For modeling the sub-grid scales, the constant Smagorinky model and the Dynamic Wale model are used in this study. First order conditional moment closure is used to model the turbulence-chemistry interaction. To calculate the conditional velocity, conditional volume averaging with smoothing is used. Two different models are used for computing the conditional scalar dissipation. One is the same procedure for the calculating conditional velocity i.e., volume averaging, and the other is to use Amplitude Mapping Closure model. A second order time accurate predictor-corrector method is used for time integration of the Favre filtered Navier-Stokes equations. تفاصيل المقالة
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  4 - MHD boundary layer heat and mass transfer of a chemically reacting Casson fluid over a permeable stretching surface with non-uniform heat source/‎sink
  B. J. Gireesha‎ B. Mahanthesh‎ M. M. Rashidi‎
  The heat and mass transfer analysis for MHD Casson fluid boundary layer flow over a permeable stretching sheet through a porous medium is carried out. The effect of non-uniform heat generation/absorption and chemical reaction are considered in heat and mass transport eq أکثر

  The heat and mass transfer analysis for MHD Casson fluid boundary layer flow over a permeable stretching sheet through a porous medium is carried out. The effect of non-uniform heat generation/absorption and chemical reaction are considered in heat and mass transport equations correspondingly. The heat transfer analysis has been carried out for two different heating processes namely; the prescribed surface temperature (PST) and prescribed surface heat flux (PHF). After transforming the governing equations into a set of non-linear ordinary differential equations, the numerical solutions are generated by an efficient Runge-Kutta-Fehlberg fourth-fifth order method. The solutions are found to be dependent on physical parameters such as Casson fluid parameter, magnetic parameter, porous parameter, Prandtl and Schmidt number, heat source/sink parameter, suction/injection parameter and chemical reaction parameter. Typical results for the velocity, temperature and concentration profiles as well as the skin-friction coefficient, local Nusselt number and local Sherwood number are presented for different values of these pertinent parameters to reveal the tendency of the solutions. The obtained results are compared with earlier results with some limiting cases of the problem and found to be in good ‎agreement.‎ تفاصيل المقالة
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  5 - Double diffusive reaction-convection in viscous fluid layer
  Vinod K. Gupta A. K. Singh
  In the present study, the onset of double diffusive reaction-convection in a uid layer with viscous fluid, heated and salted from below subject to chemical equilibrium on the boundaries, has been investigated. Linear and nonlinear stability analysis have been performed. أکثر

  In the present study, the onset of double diffusive reaction-convection in a uid layer with viscous fluid, heated and salted from below subject to chemical equilibrium on the boundaries, has been investigated. Linear and nonlinear stability analysis have been performed. For linear analysis normal mode technique is used and for nonlinear analysis minimal representation of truncated Fourier series is used. The effect of Lewis number, solute Rayleigh number, reaction rate and Prandtl number on the stability of the system is investigated. A weak nonlinear theory based on the truncated representation of Fourier series method is used to nd the heat and mass transfer. تفاصيل المقالة
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  6 - Synthesis of zinc aluminate (ZnAl2O4) by mechanochemical processing with different molar ratios of ZnS:Al
  Niloofar Ghani Kolahloo Nader SETOUDEH Abbas Mohassel Raziye Hayati Mohammad Sajjadnejad
  Zinc aluminate spinel structure (ZnAl2O4) was synthesized from mixtures of zinc sulfide (with sphalerite structure) and aluminum. The starting materials with different molar ratios were milled for 3 hours. The as-milled powders were heated isothermally at 800 ⁰C under a أکثر

  Zinc aluminate spinel structure (ZnAl2O4) was synthesized from mixtures of zinc sulfide (with sphalerite structure) and aluminum. The starting materials with different molar ratios were milled for 3 hours. The as-milled powders were heated isothermally at 800 ⁰C under an air atmosphere for one hour. The heated samples finally were washed out with diluted sulfuric acid and the remained residuals were dried at 110 ℃ for two hours. The results showed that aluminium content and the molar ratios of ZnS:Al in the starting materials have significant effect on the formation of ZnAl2O4.The as-milled results showed that although the reduction of ZnS by aluminum occurred during milling, the reaction was not completed with increasing the Al content in the starting materials. Except the molar ratio of 1:2, no signs of un-reacted Al were observed in other mixtures of ZnS-Al after milling for three hours. The XRD patterns and FT-IR spectra of the acid treated sample revealed that zinc aluminate could be synthesized from mixtures of ZnS-Al and the ZnS-Al mixture with molar ratio of 4:2 was the best among all mixtures. تفاصيل المقالة
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  7 - STUDY OF OIL SPILL ON THE SEA SURFACE IN THE PRESENCE OF THERMAL AND CONCENTRATION BUOYANCY EFFECTS
  Nirmala P Ratchagar S. V. Hemalatha
  Pollution occurs when the concentration of various chemical or biological constituents exceed a level implying negative impact on amenities, the eco-system, resources and human health. Oil spills are the serious environmental hazards which often exhibit long-term impact أکثر

  Pollution occurs when the concentration of various chemical or biological constituents exceed a level implying negative impact on amenities, the eco-system, resources and human health. Oil spills are the serious environmental hazards which often exhibit long-term impacts. The main objective of response to an oil spill is to reduce its impact on nature and human health. This paper allows us to get a comprehensive idea of the oil spill impact in the presence of thermal and concentration buoyancy effects. The governing equations and their associated boundary conditions are first cast into dimensionless form and the resulting equations are then solved analytically using perturbation technique. The effect of various physical parameters such as Grashof number, Prandtl number, Schmidt number and chemical reaction parameter on the velocity, temperature and concentration profile as well as surface skin friction, heat and mass transfer coefficients are discussed in detail with the help of graphs. تفاصيل المقالة
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  8 - Novel Bio-nanopackaging Based on Polylactic Acid/Roselle Calyx Extract/ to Enhance Quality of Hazelnut
  Narmin  Nabeghvatan Sahar  Kabiri Neda Sadat Aghayan Somayyeh  Farhang Holighi Davoud Jafarzadeh Rose  Leson
  Active biodegradable films prepared from polylactic acid (PLA)/roselle calyx extract (RCE)/Zinc Oxide Nanorod (ZnO-N) were fabricated as natural packaging materials for hazelnuts protection against microbial contamination and lipid oxidation. The PLA active films with Z أکثر

  Active biodegradable films prepared from polylactic acid (PLA)/roselle calyx extract (RCE)/Zinc Oxide Nanorod (ZnO-N) were fabricated as natural packaging materials for hazelnuts protection against microbial contamination and lipid oxidation. The PLA active films with ZnO-N (1, 3, and 5% w/w), and roselle calyx extract (0.5 g) were made by the casting solution technique. The fungal, microbial, chemical, and sensory properties of hazelnuts were measured during 9 months of conservation at 4°C. On the 6 and 9th months, moisture content was evaluated as %2.6 and 2.2% in the control sample whereas the moisture content of hazelnuts was measured as 3.6% and 2.9% packaged with PLA/RCE/%5 ZnO-N. At the last of experiments, the peroxide value (PV) was measured as 0.91 meq O2 kg-1 packaged with neat biocompatible films, whereas PV value was detected as 0.65 meq O2 kg-1 in packaged hazelnuts with %5 ZnO-N. Total microbial count ranged between 4.9 cfu g-1 for hazelnuts packaged with neat PLA and 3.7 cfu g-1 for hazelnuts specimens packaged with %5 ZnO-N after 9 months of storage. At 9 months, by increasing the level of ZnO-N from 1% to 5%, the mold count was reduced from 3.64 to 3.01 CFU g-1. The fungal contamination in the neat specimens was 3.95 CFU g-1. Sensory quality indicated that hazelnuts with ZnO-N had a significant impact on flavor and aroma, and the highest quality of sensory evaluation was related to hazelnuts packaged with PLA/5% ZnO-N/RCE. Flavor and aroma indices of hazelnuts packaged with %5 ZnO-N reached 3.5 and 4.5 respectively after 9 months of storage. The obtained findings indicate that biopackaging could be utilized to enhance microbial quality and inhibit oxidation reactions of hazelnuts during cold storage. Our results could be beneficial for introducing attractive characteristics to the biodegradable film packaging for example active film containing anthocyanin/nanofiller and can be applied when selecting a smart packaging for detection of food spoilage. تفاصيل المقالة