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Article
Reliability of the S–N line

Author: Hussain A Obaidi
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2006 Volume: 6 Issue: 1 Pages: 35-41
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: To evaluate the degree of the reliability of the S–N reference line by using highly stable referencelines (vertical and horizontal cranial axes). Materials and Methods: The sample of the studycomprised of lateral cephalometric radiographs of patients 13–18 years, 12 males and 12 females foreach of the three skeletal relationships. The ANB angles were 0–2, more than 2 and less than zerorespectively. The method was conducted by localization of the anterior superior of anterior wall of sellaturcica point (As), which is stable at age 5–6 years, drawing the Vertical Cranial Axis (VCA) whichpass through the point As and tangent to the upper part of the anterior wall of the sella turcica (at leastfor 3 mm); then, drawing the Horizontal Cranial Axis (HCA), which is perpendicular to the VCA at theAs point. The deflection and the sagittal dimension of the S–N line were measured to evaluate thevariation in the location of the points S and N, which are the determinant of the S–N line. Results:Point N had significantly local variation between gender and among the three skeletal relationships, butthat point S had insignificant local variation between gender and among the three skeletal relationships.Conclusion: The S–N line is not stable due to unstability of the location of point N.


Article
Effect of Obstacle in River on the Heat Dissipation of Hot Water Injection

Author: Ayser M. Fleh
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2009 Volume: 15 Issue: 1 Pages: 3443-3465
Publisher: Baghdad University جامعة بغداد

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Abstract

Numerical analysis of the cooling process of hot water discharge from a steam power plant into a river has been carried out in the present study. A mathematical model describing the flow field and temperature distribution induced in the river as a result of the cooling process is made based upon the assumptions of steady state, two-dimensional, turbulent flow, in the horizontal plane. The governing equations are the continuity, the momentum, the (К-ε) turbulence model and the energy equation. A proper initial and boundary condition are specified to be used in the solution of the governing equations. A numerical solution of the governing equations is made by using the control volume approach, with non-staggered grid technique and modified SIMPLE algorithm. The numerical solution is capable of calculating the velocity and temperature distributions of the calculation domain. The numerical results show that the developed algorithm is capable of calculating the flow field, properly and accurately. Results are obtained for ten cases of configuration, constant aspect ratio and weather conditions for Baghdad. The results show that the injection velocity effect on the temperature distribution and stream line , the exist of obstacle and its distance from the injection zone but the increase in injection temperature cause a small effect on temperature distribution and stream line.

تقدم هذه الدراسة تحليلا عدديآ لعملية تبريد الماء الساخن المتدفق من مكثفات محطات الطاقة الكهربائية الى النهر. فقد تم وضع نموذجآ رياضيا يصف طبيعة الجريان والتوزيع الحراري الحاصل في النهر نتيجة لعملية التبريد تلك, وقد أعتمد هذا النموذج على فرضيات منها حالة ألاستقرار,ثنائي البعد، الجريان مضطرب في المستوى الأفقي. يتضمن النموذج الرياضي أشتقاق المعادلات التفاضلية الجزئية للمسألة، والتي هي معادلات الاستمرارية، الزخم، معادلتي نموذج (K-E) للاضطراب ومعادلة الطاقة. بالاضافة الى ذلك . تم تعريف ظروف أبتدائية وحدية مناسبة لاستخدامها في حل المعادلات. تم حل المعادلات عدديآ بأستخدام تقنية الحجم المحكوم مع شبكة غير مزحفة وطريقة (SIMPEL ) المعدلة. للحل العددي القابلية على حساب توزيعات السرع ودرجات الحرارية. أظهرت النتائج العددية ان النموذج العددي الذي تم التوصل أليه له القابلية على حساب الجريان بصورة مناسبة ودقيقة ولقيمة ثابتة(نسبة طول النهر الى عرضها aspect ratio) وللظروف الجوية لمدينتة بغداد.ولقد أظهرت النتائج مياه النهر القريب من منطقة التدفق تتأثربزيادة سرعة التدفق,زيادة درجة الحرارة,قرب وبعد الجسم العائق وكذلك وجود العائق وتتأثر قليلا بزيادة درجة الحرارة.

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