A mathematical model is developed which predicates the performance of cylindrical ion exchange bed involving comparing of axial dispersion model for cation exchange column with different assumption, this model permits the performance to predicate the residence time within the bed with the variance, axial dispersion and Pecklet No. to indicated deviation from plug flow model.

      Two type of systems are chosen for positive ions first with divalent ions (Ca⁺²) to exchange with resin of Na⁺¹form used as application in  water softener units and second with monovalent ions (Na⁺¹) to exchange with resin of H⁺¹ form used as application in deionize water units &n

 تتركز مشكلة البحث في ضعف كثير من المربين معلمين كانوا أو مدرسين في التعامل مع أخطاء المتعلمين في ضوء السنة النبوية مما يؤدي إلى تعلم غير منتظم، ومن أهم أسباب هذه المشكلة قلة الإطلاع على الأساليب العملية التي ينبغي أن يتعامل بها المربي مع أخطاء المتعلمين، ولا سيما الأساليب المستمدة من القرآن الكريم والسنة النبوية، وهذا ما لمسه الباحث واقعاً من خلال ممارسته لعملتي التعليم والتدريس لمدة خمس عشرة سنة، ومن خ

    The university professor is the main theme in the educational process, then we must have prepared attention and study, it is the upper hand in achieving the objectives of education and a factor of development of society and its development factors that set it up and increase the efficiency of the duties of universities and development centers and through that evaluation is essential process and Zerorah to improve his performance, especially if they're the evaluation process from the standpoint of their students
research goals
The current research aims to identify:
1. identify the effectiveness of teaching the University of Tikrit from the standpoint of their students
2. to identify the differences in

 على الرغم من تحقق ثورة هائلة وطفرة نوعية في مجال تكنلوجيا الاتصالات في دول العالم الا ان بلدنا كان محروما من التمتع بهذه التقنيات الحديثة في ظل النظام السابق, وبعد سقوط النظام ووجود بحبوحة من الحرية، دخلت الكثير من هذه التقنيات الى العراق ومنها الموبايل والانترنيت وغيرها من وسائل الاتصال المتطورة.

ويقول (Smith & Fletcher, 2001) في كتابهما Inside Information

This paper deals with defining Burr-XII, and how to obtain its p.d.f., and CDF, since this distribution is one of failure distribution which is compound distribution from two failure models which are Gamma model and weibull model. Some equipment may have many important parts and the probability distributions representing which may be of different types, so found that Burr by its different compound formulas is the best model to be studied, and estimated its parameter to compute the mean time to failure rate. Here Burr-XII rather than other models is consider  because it is used to model a wide variety of phenomena including crop prices, household income, option market price distributions, risk and travel time. It has two shape-parame

ت لا نم ظ او ره لا يأ لاح اهلاح رضاحلا رصعلا يف ةريطخ ه ةوشرلا لثم ةيداصتقا ةميرج ديعصلا ىلع ةيبلس بقاوع اهل يتلاو زازتبلااو لاوملأا لسغو ني ىلا ةجاحلا تءاج انه نم ، يداصتقلااو يعامتجلاا تاسسؤم لبق نم اهينبت يغبني يرادلإاو يلاملا داسفلا نم دحت تامدخو بيلاسأو تاينقت ةيلاملا مئارجلا نم دحلل ةلودلا اع ىلع عقت يتلا تاسسؤملا نمو ةيئاصقتسلاا ةبساحملا وا ةيئاضقلا ةبساحملاب تلثمت ةيداصتقلاا تادحولا يف ينبت اهقت ة

Background: Optimal root canal retreatment was required safe and efficient removal of filling material from root canal. The aim of this in vitro study was to compare the efficacy of reciprocating and continuous motion of four retreatment systems in removal of root canal filling material. Materials and Methods: Forty distal roots of the mandibular first molars teeth were used in this study, these roots were embedded in cold clear acrylic,roots were instrumented using crown down technique and rotary ProTaper systemize Sx to size F2 ,instrumentation were done with copiousirrigation of 2.5% sodium hypochlorite and 17% buffered solution of EDTA was used as final irrigant followed by distilledwater, roots were obturated with AH26 sealer and Prota

Background: The most widely used material for fabrication of denture base is poly methyl methacrylate, despite its popularity, the main problems associated with it as a denture base material are poor strength particularly under fatigue failure inside the patient mouth, impact failure outside the patient mouth, which are the main causes for fracture of denture, several studies was done to increase mechanical properties of denture base. The present study was conducted to evaluate and compare the effect of addition single walled carbon nanotubes in different concentrations to polymethyl methacrylate on some mechanical properties (surface hardness, surface roughness, impact strength and transverse strength). Materials and methods: Forty eight

The toxicological risks and lifetime cancer risks associated with exposure to disinfection by-products (DBPs) including Halloacetic acids (HAAs) and trihalomethanes (THMs) compounds by drinking water in several districts in Wassit Province were estimated. The seasonal variation of HAAs and THMs compounds in drinking water have indicated that the mean values for total HAAs (THAAs) and total THMs (TTHMs) ranged from 43.2 to 72.4 mg/l and from 40 to 115.5 mg/l, respectively. The World health organization index for additive toxicity approach was non-compliant with the WHO guideline value in summer and autumn seasons and this means that THMs concentration has adverse toxic health effects. The multi-pathway of lifetime hu