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Article
Effect of curing modes on the depth of cure of resin composite

Author: Abdul–Adheem R Al–Mallah
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 10 Pages: 195-200
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To study the effect of different curing modes of Light emitting diodes (LED) curing unit on thedepth of cure (DOC) of composite resin with light and dark shades and compare the results withconventional curing method by the use of halogen curing light. Materials and Methods: A total of 40cylindrical composite resin samples (4mm diameter and 6mm height) were prepared, 20 of light shadeand 20 of dark shade. They were subjected to four curing modes (n=5 for each group): conventionalhalogen light, and three modes related to the LED light curing unit (LCU) which were: Fast (F); Ramped(R); and Pulsed (P). The samples were irradiated to the time required by the manufacturer for each curingmode, and a digital micrometer was used to measure the depth of cure according to scraping methoddescribed in ISO 4049:2000. Data were collected and analyzed for comparison. Results: No significantdifference was found in the DOC of composite irradiated by LED curing light for all of the three curingmodes or shade. However, the LED produced significantly greater depths of cure when compared withconventional halogen curing unit for both shades. The lighter shade was cured to a significantly greaterdepth than dark one when considering halogen LCU. Conclusions: All curing modes of the LED lightcan produce similar DOC regardless of composite shade when irradiated to the time recommended by themanufacturer. However, Curing with conventional halogen curing unit yielded the least DOC values forlight or dark shades when compared with LED units. Longer irradiation times are needed to cure darkshades by the use of halogen LCUs.


Article
Soft Tissue Nasal Profile Changes

Authors: Hussain A Obaidi --- Manar Y Abdul–Qadir
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: SpIss Pages: S24-S29
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To reveal the changes of the soft tissue profile of the nose, that include; length, height and depth of the nose among four age groups. Materials and Methods: The studying sample subjects included 48, 41, 50 and 44 individuals of age 11, 12, 13 and 14 years respectively. The subjects were Iraqi individuals of class I normal occlusion, who live in center of Mosul City. All subjects were radiographed with the lateral cephalometric films, these films were traced and drawing the linear parameters of the nose, the tracing involve the length (N` – Prn), width (N – Sn) and depth (Prn – Prn`). The results were subjected to the descriptive and variance analyses. Results: The results appeared in males the length of the nose increase in dimension with no significant differences when compared among the four age groups, whereas in females showed significant increase when compared the 11, 12 years with 13 years and with 14 years age groups. While, the h weight of the nose (N`– Sn) appeared in males and females significantly increase at 14 years age group when compared with other age groups. But significantly increased at 12 years age group as compared with 11 years age group, in males only. Mean while, the depth of the nose (Prn – Prn`) displayed significantly increase at age 14 years group when compared with 11 and 12 years age groups for both sexes. The comparison between sexes for the nose parameters demonstrated that the length, width and depth of the nose displayed significantly increase in males than females at 11 years age group and no significantly differences at other age groups. Conclusions: The conclusions of the study are that the nose have significantly increase between 11 and 14 years age group in both sexes, the nasal profile parameters have insignificant difference in dimensions among 12, 13 and 14 years age groups.


Article
The Effect of Light Curing Tip Distance on Curing Depth of Resin Composite: A Comparative Study

Author: Ashraf S Qasim
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: SpIss Pages: S78-S83
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To determine the correlation between intensity (I) of light–emitting diode (LED) and tungsten–halogen light sources, and depth of cure of a resin composite at different distances. Materials and Methods: LED curing light (Ultra Lite 200E plus) and tungsten halogen light (Astralis 5 Vivadent) were evaluated. Intensity was measured at distances of 0, 2, 4, 6, 8, and 10mm between the light tip and detector. A blackened aluminum plate, 0.5mm thick, with a 4mm–diameter aperture was placed over the detector. The use of this aperture limited the amount of light reaching the detector to a uniform area for both curing lights and also corresponded to the area of the mould for the depth of cure studies. Both light tips were centered on this aperture to reduce any influence of varying I across the light tip. Depth of cure (DOC) of light–curing universal micro hybrid composite shade A2 was also measured. A metallic mould was used to measure the depth of cure at distances of 0, 2, 4, 6, 8, and 10mm between light tip and mould. The degree of divergence of the light of both light curing units was also determined by tracing the illuminated area at a 10mm distance for each of the curing lights. Results: For both lights, intensity decreased as distance increased. While, both I and DOC decrease with increasing distance, the relationship between these factors and distance may not be similar for both lights and may depend on the characteristics of individual lights. Conclusions: Both I and DOC decreased with increasing distances. DOC usually decreases with decreasing I, the rate of decline varies between various light brands.


Article
EFFECT OF COHESIVE AND NONCOHESIVE SOILS ON EQUILIBRIUM SCOUR DEPTH
تأثير الترب المتماسكة وغير المتماسكة على عمق الانجراف المتوازن

Author: .د. صالح عيسى خصاف
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2007 Volume: 14 Issue: 2 Pages: 73-86
Publisher: Tikrit University جامعة تكريت

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Abstract

In this research ,the effect of cohesive soils ( clay ) and non –cohesive soils sand on equilibrium scour depth was studied .Experiments were carried out on two types of clay and two types of sand as a bed material using an obstruction ( pier ) to create a local scour. The effect of flow velocity and Froude number on scour depth and the occurrence time of equilibrium scour depth were studied .
The results show that for the same conditions, the rate of scour in the clayey soils is less than in sandy soils. Also the time required for occurrence of the maximum scour depth ( equilibrium depth ) in clayey soils is more than in sandy soils. Two formulas were found to predict the equilibrium scour depth in terms of Froude number ,the first is for clayey soils and the second for sandy soils .

KEYWORDS
Cohesive soil, Non-cohesive soil , Scour depth

في هذا البحث ، تم دراسة تأثير الترب المتماسكة ( الطينية ) والترب غير المتماسكة ( الرملية ) على عمق الانجراف المتوازن ، حيث تم إجراء تجارب مختبرية على نوعين من الترب الطينية وعلى نوعين من الترب الرملية كمادة للقاع بوضع عائق خلال الجريان ( دعامة ) يحدث انجراف موقعي فيه و بحث تأثير سرعة الجريان ورقم فرود على عمق الانجراف وعلى وقت حدوث عمق الانجراف المتوازن . وتبين من خلال البحث إن معدل الانجراف في الترب الطينية يكون اقل مما هو عليه في الترب الرملية وان الوقت اللازم لحدوث أقصى عمق انجراف ( العمق المتوازن ) في الطينية أطول مما هو عليه في الترب الرملية ولنفس ظروف الجريان . وقد تم التوصل إلى معادلتين لإيجاد قيمة عمق الانجراف بربط عمق الانجراف نسبة إلى عمق الجريان ورقم فرود لكل من التربة الطينية و الرملية وقد تم التحقق من صحتها فكانت النتيجة جيدة .


Article
Effect of Depth and Location of cracks on the natural
تأثير أعماق ومواقع الشقوق على الترددات الطبيعية للعتبات الحيدية

Author: Mohammed Najeeb Abdullah محمد نجيب عبدالله
Journal: AL Rafdain Engineering Journal مجلة هندسة الرافدين ISSN: 18130526 Year: 2007 Volume: 15 Issue: 1 Pages: 27-36
Publisher: Mosul University جامعة الموصل

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Abstract

Abstract In this work , the influence of the location and depth of transvernce cracks on the natural frequency of cantilever beam was studied. The study of the cracked beam has been carried out theoretically, starting from derivation of equation for the additional strian energy in the presence of a crack .The equation of natural frequency change due to the presence of a crack can also be calculing for cantilever beam . The results showed that the presence of the crack causes a decrease in the values of the natural frequencies of beam as the decrease in the value of natural frequencies of the beam with cracks in the area nearer to the supports, was lesser than in areas away from the supports. Finally, the theroetical results were compared with the experimental results of previous researches, which were in a cloce agreement especially for the behavior of beam curves as function of the crack depth.Key Word : Beam , Crack , Natural Frequency, Depth , Location

الملخصفي هذا البحث ، تم دراسة تأثير أعماق ومواقع الشقوق المستعرضة على الترددات الطبيعية لعتبة حيدية مثبتة من جهة وسائبة من جهة أخرى تحليلياً . أبتداءاً من اشتقاق معادلة حساب طاقة الانفعال الإضافية نتيجة الشق فقد تم التوصل إلى علاقة التغير في التردد الطبيعي عند وجود الشق وحسب ظروف تثبيت العتبة . أظهرت النتائج الرياضية إن وجود الشقوق سبب انخفاضاً في قيم الترددات الطبيعية للعتبة ، إذ أن الانخفاض في نسبة الترددات الطبيعية للعتبة المتضمنة شقاً في مواقع قريبة من منطقة التثبيت كانت قليلة جداً مقارنة بالمواقع البعيدة لتثبيت العتبة . وأخيراً تم مقارنة النتائج الرياضية مع بعض النتائج العملية لبحوث سابقة فكانت متقاربة وخصوصاً في سلوك منحنيات تردد العتبة كدالة لعمق الشق .الكلمات المفتاحية : عتبة ، شق ، تردد طبيعي ، عمق ، موقع


Article
Estimation of Critical Bed Depth in Fixed Bed Of Granular Activated Carbon

Authors: Waleed M. Abood --- Abbas H. Sulaymon عباس حميد سلمون
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2007 Volume: 13 Issue: 4 Pages: 1974-1981
Publisher: Baghdad University جامعة بغداد

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Abstract

The aim of this study is estimating the critical bed depth in adsorption process through a fixed-bed of granular activated carbon at different bed depths of 0.03, 0.05, 0.08and 0.11m at influent furfural concentration in waste water of 0.2 kg/m3, with constant flow rate of (16.66) × 10-5 m3/min and adsorbent particle size (0.5-1.5) mm. the changing of flow rate and furfural influent concentration had been studied to determine their effects on the critical bed depth value by using bed depth- service time method (BDST). Length of unused bed (LUB) and length of equivalent section of bed had been estimated mathematically during process of the adsorption at different bed depths and during changing the flow rate(8.3× 10-5 m3/min) and influent concentration at same bed depth (0.05m).

الهدف من هذه الدراسة هو احتساب عمق الحشوة الحرج لعملية الامتزاز في حشوة ثابتة من الفحم المنشط الحبيبي ذات اعماق متنوعة هي (0.03, 0.05 , 0.08, 0.11 ) م بثبوت كل من معدل الجريان بقيمة (16.66 ) × 10-5 م3/ دقيقة , وتركيز الفورفورال الداخل في المياه المختلفة (0.2) كغم/م3 وحجم حبيبات الفحم ( 1.5 – 0.5 ) ملم. تغير معدل الجريان وتغير تركيز المادة الداخلة تـم دراستها لغرض تحديد تأثير عمق الحشوة الحرج باستخدام طريقة عمق الحشوة – زمن الخدمة) . طول الحشوة الغير مستخدم والطول المكافئ للحشوة المستخدمة تم تحديدها رياضياً خلال عملية الامتزاز للظروف اعلاه ودراسة تأثير تغير معدل الجريان وتركيز المادة الداخلة عند ثبوت اعماق الحشوات المستخدمة.

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