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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
Measures: 
  • Views: 

    426
  • Downloads: 

    0
Abstract: 

در این مقاله شبیه سازی به روش لاگرانژی برای حرکت ذرات و مدل تلاطمی تنش رینولدز برای بررسی اثر وارونگی در پخش آلاینده ها از یک منبع نقطه ای به کار گرفته شده است. به منظور ارزیابی دقت مدل، نیمرخ های سرعت و دمای جریان جوی خنثی به مدل اعمال شده و با نیمرخ های مشابه در پایین دست که از اجرای مدل به دست می آید مقایسه می گردند. شرایط وارونگی ارتفاع یافته به صورت نیمرخ دمای شرایط خنثی که شیب آن در محل وارونگی به نیمرخ دمای شرایط پایدار تبدیل شده شبیه سازی شده است. اثر ارتفاع وارونگی در پخش آلاینده ها با تغییر در ارتفاع نقطه تغییر شیب نیمرخ دمای اعمال  شده بررسی می گردد. نتیجه بررسی نشان می دهد که انرژی جنبشی تلاطمی جریان هوا شدیدا به نیمرخ دما وابسته است. حداکثر میزان انرژی تلاطمی حدود 50 درصد ارتفاع وارونگی رخ می دهد. تغییرات انرژی تلاطمی در پایین دست منبع تقریبا تا 25 درصد ارتفاع وارونگی مستقل از فاصله از منبع بوده و فقط تابعی از ارتفاع (تقریبا به صورت خطی) است. در ارتفاعات بالاتر از 25 درصد، تغییرات انرژی تلاطمی در پایین دست منبع به ارتفاع وارونگی بستگی دارد، به طوری که در این مطالعه برای وارونگی با ارتفاع 200 متر انرژی تلاطمی ذرات آلاینده با دور شدن از منبع کاهش، در مورد وارونگی با ارتفاع 400 متر تقریبا ثابت و در مورد وارونگی با ارتفاع 600 متر افزایش می یابد. بنابراین در نظر گرفتن نیمرخ دما و نوع وارونگی در طراحی می تواند در تعیین ارتفاع تجهیزاتی چون مشعل ها و خروجی های واحدهای صنعتی به محیط، مهندسین طراح را هدایت کرده و ارزیابی زیست محیطی مجتمع های صنعتی را موفقیت آمیز نماید.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2010
  • Volume: 

    44
  • Issue: 

    1
  • Pages: 

    43-52
Measures: 
  • Citations: 

    0
  • Views: 

    877
  • Downloads: 

    0
Abstract: 

In this paper, we studied effect of different parameters including density, viscosity, interfacial tension and solute transfer concentration on phase inversion hold-up. The results showed that change in phase density ratio had no effect on phase inversion hold-up. It also disclosed that the phase viscosity ratio was the most effective parameter affecting phase inversion hold-up and each phase had tendency to increase dispersion by rising viscosity of that phase. When the proportion of dispersed phase viscosity to continuous phase viscosity was more than 1, phase inversion hold-up decreased as the interfacial tension increased or Vice versa. Also, increase in the solute transfer concentration by affecting phases physical properties and electrostatic interaction between drops and continuous phase resulted in increasing the tendency toward both types of inversion and.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
Measures: 
  • Views: 

    326
  • Downloads: 

    0
Abstract: 

در این مقاله شبیه سازی به روش لاگرانژی برای حرکت ذرات و مدل تلاطمی تنش رینولدز برای بررسی اثر وارونگی در پخش آلاینده ها از یک منبع نقطه ای به کار گرفته شده است. به منظور ارزیابی دقت مدل، نیمرخ های سرعت و دمای جریان جوی خنثی به مدل اعمال شده و با نیمرخ های مشابه در پائین دست که از اجرای مدل به دست می آید مقایسه می گردند. شرایط وارونگی ارتفاع یافته به صورت نیمرخ دمای شرایط خنثی که شیب آن در محل وارونگی به نیمرخ دمای شرایط پایدار تبدیل شده شبیه سازی شده است. اثر ارتفاع وارونگی در پخش آلاینده ها با تغییر در ارتفاع نقطه تغییر شیب نیمرخ دمای اعمال شده بررسی می گردد. نتیجه بررسی نشان می دهد که انرژی جنبشی تلاطمی جریان هوا شدیدا به نیمرخ دما وابسته است. حداکثر میزان انرژی تلاطمی حدود 50 درصد ارتفاع وارونگی رخ می دهد. تغییرات انرژی تلاطمی در پایین دست منبع تقریبا تا 25 درصد ارتفاع وارونگی مستقل از فاصله از منبع بوده و فقط تابعی از ارتفاع (تقریبا به صورت خطی) است. در ارتفاعات بالاتر از 25 درصد، تغییرات انرژی تلاطمی در پایین دست منبع به ارتفاع وارونگی بستگی دارد، به طوری که در این مطالعه برای وارونگی با ارتفاع 200 متر انرژی تلاطمی ذرات آلاینده با دور شدن از منبع کاهش، در مورد وارونگی با ارتفاع 400 متر تقریبا ثابت و در مورد وارونگی با ارتفاع 600 متر افزایش می یابد. بنابراین در نظر گرفتن نیمرخ دما و نوع وارونگی در طراحی می تواند در تعیین ارتفاع تجهیزاتی چون مشعل ها و خروجی های واحدهای صنعتی به محیط، مهندسین طراح را هدایت کرده و ارزیابی زیست محیطی مجتمع های صنعتی را موفقیت آمیز نماید.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2025
  • Volume: 

    20
  • Issue: 

    1
  • Pages: 

    61-65
Measures: 
  • Citations: 

    0
  • Views: 

    2
  • Downloads: 

    0
Abstract: 

Acute uterine inversion is a rare but life-threatening condition that occurs when the uterine fundus collapses into the endometrial cavity, typically following placental separation after delivery. This condition can lead to shock, severe hemorrhage, and even maternal death. The patient is a 23-year-old woman at 39 weeks of gestation who presented with severe abdominal pain, changes in vaginal appearance, and the absence of a palpable uterus on abdominal examination following vaginal delivery. She was immediately transferred to the operating room with a suspected diagnosis of uterine inversion. Under general anesthesia, uterine relaxants were administered, and the uterine fundus was successfully repositioned using a two-handed manual maneuver. The uterus was held in its natural anatomical position for several minutes while uterotonic agents were administered to promote and maintain continued contraction. Fortunately, the patient responded well to the intervention, and the uterine inversion was effectively managed.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    10
  • Issue: 

    3
  • Pages: 

    139-162
Measures: 
  • Citations: 

    0
  • Views: 

    57
  • Downloads: 

    0
Abstract: 

This study was aimed at examining the types of inversion and their severity using the thermodynamic indices of the atmosphere such as SI, LI, KI and TT at Bandar Abbas Station for 2010-2020. In this study, Radioosvand data at the Bandar Abbas Station was obtained and used from the University of Wioming for the last 11 years (3. 5 local) during the last 11 years (2010 to 2020). The results of the analysis showed that the average number of inversion phenomenon in Bandar Abbas was 501 cases per year, as in some days several types of inversion were observed at different altitude. Of these inversion, about 31. 6 % are related to radiation temperature inversion, 4. 3 % front, and another 64. 1 % for subsidence inversion. Due to the air session underneath, the share of subsidence inversions is more than other types of inversion. In the meantime, the most severe inversion of subsidence was 1354 and the weakest inversions were with 29 cases and fronts. In general, the long-term average intensity coefficient of inversion of Bandar Abbas station with a coefficient of 0. 062 indicates that the intensity of the city's inversion is mostly extremely severe, which can be very destructive effects both environmentally and physical health in the city's residents. Bandar Abbas follow. The correlation between the inversion elements also showed that by reducing the thickness of the inversion layer, the intensity of temperature inversion also increased.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

SADEGHI E.

Issue Info: 
  • Year: 

    2010
  • Volume: 

    20
  • Issue: 

    75 (PHYSICS ISSUE)
  • Pages: 

    122-127
Measures: 
  • Citations: 

    0
  • Views: 

    782
  • Downloads: 

    135
Abstract: 

Introduction: Semiconductor nanostructures have attracted much attention due to its application in the development of optoelectronic devices. In these structures the electron spectrum comprises a set of discrete levels. On the other hand, donor impurity in quantum dots can alter the properties of a quantum devices.Aim: Study of the effect of external electric field on the impurity binding energy in a spherical quantum dot.Materials and Method: The energy levels are investigated using variational method within the effective mass approximation and finite barrier potential.Results: The energy of impurity and binding energy are calculated in terms of radius of quantum dot. The binding energy is reduced with increases the radius of dot. The ground state energy of electron, impurity energy, and normalized binding energy versus electric field for different dot radii in finite quantum dot are also calculated.Conclusion: The results show the energies decrease with increases the strength of electric field.

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    11
  • Issue: 

    1
  • Pages: 

    18-35
Measures: 
  • Citations: 

    0
  • Views: 

    36
  • Downloads: 

    0
Abstract: 

Statistical analysis of temperature inversion and its types in Birjand city using by inversion intensity indexIntroductionThe ambient air temperature in the troposphere usually decreases with increased altitude (per 1000 meters increases the height of 5 to 6 degrees Celsius), but sometimes with increased air temperature, which is called temperature or inversion inversion. Temperature inversion occurs when a layer of hot air is above cold air adjacent to the Earth. In this case, air stability is created and instead of increasing temperature height to a few hundred meters above Earth with increased height. We will increase temperature. The importance of temperature inversion phenomenon is doubled when examining the effects of temperature inversion phenomenon. The phenomenon of temperature inversion is important because it causes fumation. This phenomenon occurs when the sun's radiation is unstable in the vicinity of the surface for a short time after sunrise, then combined with the scattered material in the nightly layer, causing the scattered material to return to the surface. . As a result, the concentration of pollutants increases sharply and the phenomenon of fiomia is created.MethodologyIn this study, the daily data of the radio atmosphere above the Birjand Synoptic Station (Table 1) for 00 Greenwich (3.5 local) over the last 11 years (2010 to 2020) to 11 km high from Earth from Vioming University He got. Indicators used include thermodynamic indices such as SI, LI, KI and TT and potential temperature. Also of other data used in this study, radiosvand transmitted information including inversion height from ground to meter (ZBASE), inversion height from ground to meter (ZTOP), base temperature in base and inversion layer to degree Selicius (TBASE), the temperature difference between the base and the top of the inversion layer to the grade of silicius (DTINV) is the height difference between the base and the apex of inversion to meter (DZINV) and the pressure in the base (PBSE) and the inversion layer (PTOP) from Relationships (1 and 2) are calculated First calculated using the relationship (1) the potential of the ceiling and the floor of the inversion layer of the relationship (1)Θ: Potential temperature to Kelvin grade T: Temperature to KelvinP: Air pressure to hectopaskalAfter calculating the potential temperature of the ceiling and floor of the inversion layer using the relationship (1), we have calculated the intensity of temperature inversion using relationship (2) on a monthly, seasonal and annual time scale. Relationship (2):Δθ Difference of the temperature potential and the base of inversion to the grade of KelvinΔz thick layer of inversion to meter Z station height to hectometryResults and DiscussionThe results showed that the average annual temperature inversion phenomenon at Birjand Station was about 90 cases per year, as it may not occur in different heights in some days, about 11.1 % of the radiation temperature inversion, front. A 12.4 %, and the other 76.5 % is related to temperature inversion of subsidence. Due to the air session underneath, the share of subsidence inversions is more than other types of inversion. The results showed that the highest average inversion layer in Birjand was formed in 2010 and 2015 at 9 ° C. The highest annual temperature of the inversion is related to the inversion of subsidence, which is due to the subsidence of the air subcutaneous air subcutaneous in the upper layers of the atmosphere and the high temperature on the ground. In terms of annual altitude, the highest height of the inversion layer occurred in 2019 with 4490 meters. In terms of thickness of the inversion, the inversion of the type of subsidence with 207 and the radiation with 145 meters form the thickest and the thinnest layer of inversion. Results of the average inversion layer pressure in Birjand showed that 2014 and 2015 were formed with about 870 miles and 2019 with 592 milligrams. Among the types of inversion, the most severe inversion of the front was 0.044 % and then subsidence with 0.030 %. In terms of the intensity of severe inversion with 0.7 % and poor inversions with 0.92 % were the lowest and the highest in Birjand. In fact, the inversions of the city of Birjand are poor because of their physiographical and geographical properties.ConclusionThe correlation results also showed that there was a direct and significant relationship between the intensity of inversion and the inversion layer temperature at 99 %. That is, the higher the temperature of the inversion layer, the greater the inversion of inversion and vice versa. But there is a significant relationship between the inversion intensity and the height of the layer at 95 % probability level. This reverse relationship indicates that whenever the inversion layer occurred at the lower altitude, the inversion of inversion has also increased; But the relationship between the thickness and intensity of the inversion layer showed that with the increase in the thickness of the inversion layer, the inversion of inversion in Birjand also increased as the layer temperature was higher as the inversion was more severe. There is also a direct and significant relationship between the intensity and pressure of the inversion layer at 95 % so that with increased pressure, the inversion will increase. In general, the city of Birjand is under the tranquility of the tropical climate because of its specific location, which is also on the roads of 120 -day Sistan, so it will be weak if inversion occurs.Keywords: temperature inversion, barley thickness, inversion intensity, barley pollution, Birjand

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    17
  • Issue: 

    20
  • Pages: 

    89-105
Measures: 
  • Citations: 

    1
  • Views: 

    1991
  • Downloads: 

    0
Abstract: 

The purpose of the present study was to investigate the levels of temperature inversion and the effects it causes on the air pollution of Tehran. To this aim, 100 days from 2005 to 2009 which had the highest pollution levels were chosen from five stations. The inversion levels for these days were investigated through Skew-T graphs and the earth pressure plans in the levels of 900 to 300 hecto pascal. The results showed that between 73 to 85.5 percent of the air pollution in the Tehran stations are due to pressure systems and the high level of radiance from earth surface. The level of CO, PM10, SO2, was highest in Azadi station. The level of CO2 was highest in Rey station. The level of O3 was highest in Rey station. Although, the direction of the wind is from west to east but due to invergen as well as the low speed of wind, the wind flow does not influence the weather condition. Also, the spatial distribution of the weather pollution of Tehran showed that the amount of pollution is higher in center and west. In addition, from north to south the level of NO2 and O3 increase and the levels of CO, PM10, and SO2, decrease.

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Issue Info: 
  • Year: 

    2020
  • Volume: 

    78
  • Issue: 

    3
  • Pages: 

    183-187
Measures: 
  • Citations: 

    0
  • Views: 

    459
  • Downloads: 

    0
Abstract: 

Background: Nonpuerperal uterine inversion is a rare medical condition that many gynecologists might not be encountered even with one case during their entire medical practice. It refers to the expulsion of uterine corpus from the dilated cervix resulting in uterus being turned inside out. There are two kinds of uterine inversion, puerperal and non-puerperal, which the second condition is less common. Acute uterine inversion usually presented by crampy abdominal or pelvic pain, vaginal bleeding, anemia, and even symptoms of severe sepsis. We describe a case of uterine inversion in a postmenopausal woman. Case Presentation: A 66 years old grand multiparous woman (6 normal vaginal delivery) who was menopause since 15 years ago, was referred to the emergency unit of an academic hospital of Mashhad University of Medical Sciences at October 2016 due to postmenopausal uterine bleeding, cramp-like abdominal pain and mass protrusion from the vagina. The vital sign was stable at the first visit but a big non-necrotizing red vaginal mass was protruded from vaginal opening that connected to other soft intravaginal mass. Abdominal ultrasonography revealed the dilated vaginal cuff and some air-fluid levels in the uterine cavity. The patient referred to the operative room and vaginal myomectomy was done with diagnosis of pedunculated submocusal leiomyoma. Then, total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed after the correction of uterine inversion by abdominoperineal approach. Conclusion: Acute uterine inversion is a potentially dangerous condition (due to vaginal bleeding, severe abdominal or pelvic pain, and the possibility of uterine necrosis and even systemic infection). This condition should be considered as an important differential diagnosis as a vaginal mass in the post-menopausal period.

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Issue Info: 
  • Year: 

    1384
  • Volume: 

    24
Measures: 
  • Views: 

    1401
  • Downloads: 

    0
Abstract: 

پایداری جوی ناشی از وارونگی دمایی یکی از مهمترین علل افزایش پتانسیل آلودگی هوا به خصوص در کلان شهرها از جمله شهر اصفهان است. به طور طبیعی در لایه تحتانی جو (تروپوسفر) با افزایش ارتفاع، دما بطور آدیاباتیک خشک (بی درو) کاهش می یابد، یعنی هوای سطح زمین که در مجاورت زیست کره واقع شده گرمتر از سطوح بالاتر است، لذا در چنین شرایطی نوسانات عمودی جو به راحتی مهیا شده و هوای سطح زمین با هوای پاک و پاکیزه سطوح بالایی جابه جایی صورت داده و تهویه طبیعی به این شکل انجام می گیرد.اگر شرایط به گونه ای باشد که با افزایش ارتفاع دما نیز افزایش یابد، یعنی هوای مجاور سطح زمین سردتر از سطوح بالایی باشد، در این حالت جابه جایی عمودی جو متوقف شده و هوای سطح زمین به حالت پایدار مسکوت می گردد، به چنین حالتی وارونگی دمایی یا اینورژن گفته می شود، و از آنجایی که منابع آلاینده هوا، به طور دائم آلاینده های خود را در داخل لایه سطحی تزریق می کنند، لذا غلظت آلاینده ها در این شرایط به شدت افزایش می یابد. آلودگی هوا موقعی به شدیدترین حد خود می رسد که پدیده وا رونگی، با ارتفاع کم و برای مدت طولانی تر در هوای شهر باقی بماند. در واقع لایه اینورژن با ارتفاع کم و مدت زمان مدید، حائل پایدار و ساکنی ایجاد می کند که مانع اختلاط این سطح با سطوح بالایی شده و با افزایش غلظت آلاینده ها در زیر آن، آلودگی هوا تشدید می شود. در این مقاله به بررسی موردی اینورژن شهر اصفهان پرداخته شده است، بدین منظور اطلاعات جو بالای ایستگاه اصفهان طی سال های 1991 لغایت 1993 میلادی در ساعت 00 گرینویچ (3.5 بامداد محلی)، جمع آوری شده و مورد بررسی قرار گرفته است. نتایج حاکی از آن است که وارونگی دما یی طی دوره مورد پژوهش در شهر اصفهان، در تمام فصول سال برقرار بوده و به دلیل واجد بودن شرایط اینورژن، پایداری جوی سطح زمین برقرار بوده است و 80 درصد از روزهای 3 سال مورد بررسی شرایط اینورژن حاکم بوده است اما ارتفاع لایه وارونگی با تغییر فصول، تغییراتی داشته است و کمترین قطر لایه وارونگی حدود 40 متر در ماه مارس و بیشترین قطر لایه وارونگی در حدود 1212 متر در ماه نوامبر بوده است.

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