research centers


Search results: Found 13

Listing 1 - 10 of 13 << page
of 2
>>
Sort by

Article
Effect of Loading Type on Generated Stresses around a Circular Tunnel Lining in Sand
تاثير نوع الحمل على الأجهادات المتولدة حول بطانة نفق دائري في الرمل

Author: T. M. Toma
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2008 Volume: 26 Issue: 6 Pages: 602-608
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

The study is carried out to investigate the behavior of tunnel lining in sandy soil byevaluating the magnitudes of the generated stresses that are generally required to ensure thesafety of tunnel construction. The testing program comprised different factors, i.e., sanddepth, density with and without the effect of surface loading. The experimental work wasaccomplished through an instrumented (strain gauged) circular tunnel model. It was shownthat the generated stresses, for different loading types, i, e., surcharge, circular or striploading, decreased as the sand density increases for all regions (Crown, Shoulder & Springline)and they increase as the sand depth increases. The results are presented in the form ofdesign charts.

أجري البحث لغرض دراسة تصرف بطانة نفق في التربة الرملية عن طريق تقييم مقدار الأجهاداتالمتولدة فيه والتي تتطلب تأمين عامل الأمان أثناء عملية الأنشاء. برنامج الفحوصات تضمن عواملمختلفة منها:- عمق الرمل، الكثافة مع وبدون تأثير الأحمال السطحية. الجزء العملي من البحث قد انجزمن خلال الاستعانة بانموذج نفق مختبري دائري مزود بخلايا تحسس الاحمال . النتائج بينت أنالأجهادات المتولدة نتيجة تغير نوع الحمل (الحمل المنتظم, الحمل الدائري, أو الحمل الشريطي) تقل كلماازدادت كثافة الرمل ولجميع المناطق على محيط مقطع النفق وأن تلك الأجهادات تزداد مع زيادة عمقالرمل. النتائج تم استعراضها على هيئة مخططات تصميمية.

Keywords

Tunnels --- Lining --- Stresses --- Loading Type.


Article
Effect of Microwave Disinfection on Hardness of Acrylic Base Denture Lin-ing Material

Author: Marwah M Shehab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 21 Pages: 128-135
Publisher: Mosul University جامعة الموصل

Loading...
Loading...
Abstract

Aims: To evaluated the effect of the repeated microwave disinfection on hardness of vertex denture lining material cured by water bath and microwave. Materials and Methods: Twenty specimens were prepared 4.5 mm thickness × 25 mm in diameter from denture lining material (Vertex , Holland) ad-hered to specimen 2.5 mm thickness × 50 mm in diameter form a heat-cured acrylic resin (Vertex, Holland) and divided into two main groups according to the curing method (waterbath and microwave). The specimens were divided as following, ten specimens, five for each curing method as a control group. The other ten, five specimens for each curing method for microwave disinfection, specimens immersed in 200 ml of distilled water and irradiated with 540 Watt per 3 minute, three times weekly for one month started from the first time of microwave irradiation (microwave disinfection) to twelve times, tested for hardness by using Shore –A- hardness durometer. Results: The independent t-test revealed that, significant differences between control groups (specimens cured by water bath higher than that cured by microwave method), and significant differences between first time of disinfection by domestic microwave oven cured by two methods. The analysis of variance (ANOVA) and Duncan multiple range test confirmed there is a significant difference in hardness of denture lining material in different times of disinfection by domestic microwave oven for both curing methods at significant level (P≤ 0.01). Conclusion: The repeated disinfection by microwave irradiation deteriorated the vertex den-ture lining material regardless to the curing methods.


Article
Laboratory Assessment for Clays Used for Filling Dams,Dykes and Embankments
التقويم ألمختبري للأطيان المستخدمة في تبطين وبناء ألسدود و ألسداد و الخزانات

Author: د . خالد أحمد عبد ألله ألحداد
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2011 Volume: 18 Issue: 1 Pages: 42-57
Publisher: Tikrit University جامعة تكريت

Loading...
Loading...
Abstract

Laboratory tests and analysis results for materials chosen from al-Adhaim site indicate that either suitable according to American Standards for use as clays quarries for filling ,dams ,dykes and embankments or unsuitable for one or more reasons . Treatments take place ,according to type of problems for example physical problem , as excess in silt and sand particles percentages , also decrease in clays particles percentage ,vice versa. In addition to physical foul, many treatments can be done , chemical problems such as excess in gypsum content, total dissolved salts and organic materials according to British Standards. In addition to chemical foul, by grass, plants roots , treatments done which can be done according to the causes of these problems.


Article
Evaluation the Effect of Different Methods of Disinfection on Tensile Strength and Bond Strength of Soft Denture Lining Ma-terials

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 21 Pages: 58-65
Publisher: Mosul University جامعة الموصل

Loading...
Loading...
Abstract

Aims: Aim of the study to evaluate the effect of two different disinfection methods for two periods of time on tensile strength and bond strength of soft denture lining materials (Vertex and Molloplast-B). Materials and methods : The effect of two disinfection methods ,first chemical disinfection method (which include artificial saliva , saturated salt and vinegar solution), and second microwave method on two physical properties the tensile and bond strength of soft denture lining materials for two periods of times (14 and 30 days) was evaluated, two hundred samples were prepared, one hundred samples to each property test . ANOVA and Duncan's multiple range test were performed to determine the signifi-cant difference among the tested groups at p ≤ 0.05% . Results: The result showed that the highest val-ue of tensile and bond strength of Vertex after 14 and 30 days were achieved with the microwave group, while for Molloplast -B highest value achieved with the control distilled water group. The low-est value was achieved after immersion in vinegar group for both soft lining material. A significant difference between the two soft lining materials among all disinfection methods at p≤ 0.05.Conclusions : The results appeared that the chemical disinfection and microwave disinfection methods have a significant effect on the tensile strength and bond strength of both vertex and Mol-loplast –B soft ling materials for two periods of time. Microwave disinfection has less effect than the chemical disinfection on the properties. The effect of disinfection increase significantly with increas-ing period of time .


Article
Preparation of Refractory Mortar from Iraqi Raw Materials

Author: Duraid F. Mahdi
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2015 Volume: 11 Issue: 2 Pages: 37-40
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

Loading...
Loading...
Abstract

In this work, scraps from fire-clay brick were used to make refractory mortar by adding Iraqi kaolin (Alduejlh Zone) at different percentage contents (21, 27, 32, 40 and 47%). By crushing and milling, the mixtures of kaolin stone and fire-clay brick scraps were converted into powders of different particle sizes. The specimens were made as disks for the measurements of bulk density, water absorption, thermal conductivity, specific heat capacity and bond strength. The specimens with 40% kaolin showed the best properties as they are closer than others to the fire-clay brick properties.


Article
Evaluation the Effect of Different Methods of Disinfection on Surface Roughness of Soft Denture Lining Materials

Authors: Lamia T Rejab --- Ihssan F Al-Takai
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 22 Pages: 296-304
Publisher: Mosul University جامعة الموصل

Loading...
Loading...
Abstract

Aims: Aim of the study to evaluate the effect of two different disinfection methods for two periods of time on surface roughness of soft denture lining materials (Vertex and Molloplast-B). Materials and methods : The effect of two disinfection methods ,first chemical disinfection method (which include artificial saliva with saturated salt and artificial saliva with vinegar solution), and second microwave method on the surface roughness of soft denture lining materials for two periods of times (14 and 30 days) was evaluated, One hundred samples were prepared. ANOVA and Duncan,s multiple range test were performed to determine the significant difference among the tested groups at p ≤ 0.05% .Results: The results showed that the lowest value of surface roughness (Ra)value after 14 and 30 days for Vertex soft denture lining material was achieved with the microwave group, while the lowest value of surface roughness (Ra)value after 14 and 30 days for Molloplast-B was achieved with the distilled water. The highest value of surface roughness (Ra) for Vertex soft denture lining material was achieved with vinegar after 14 and 30 days., while for Molloplast-B was achieved with vinegar group after 14 days and with salt group after 30 days. Conclusion : The results of T-test Table showed that there were no statistically significant differences in surface roughness(Ra) value between Vertex and Molloplast -B soft denture lining materials after 14 and 30 days except for microwave group after 14 days at P value ≤ 0.05. Distilled water disinfection has less effect on the property than other chemical disinfection and microwave regimen. The effect of disinfection increase significantly with increasing period of time.


Article
The Influence of Silica Dioxide and Aluminum Oxide Nano Fillers Reinforced Heat Cured Acrylic Denture Base Material and Thermocycling on Tensile and Shear Bond to Denture Soft Lining Material

Author: Dr. Hikmat J. Al-Judy. B.D.S., M.Sc., Ph.D. د. حكمت جميل
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2017 Volume: 14 Issue: 1 Pages: 99-109
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

Background: Soft lining materials play an important role in modern prosthodonticstreatment because of their capability to restore the inflamed and distorted mucosa.The purpose of the research was to estimate the influence of acrylic denture basereinforcement with silanted nano fillers (Al2O3 and Sio2) separately on tensile andshear bond strength of soft lining material and studying effect of thermo cyclingon bonding strength.Materials and methods: Total 120 specimens were prepared; it divided into 60Specimens for shear bond strength test and 6o specimens for tensile bond strengthtest. Specimens were sub grouped into 30 Specimens without thermo cycling and30 specimens with thermo cycling. Each sub group is consisted from: 10Specimens control, 10 specimens were reinforced with 2 wt% of Al2O3 nano fillersand 10 specimens were reinforced with 5 wt% of SiO2 nano fillers. Samples wereprocessed depending on test applied. Soft lining material was applied for eachtesting group. Samples were immersed in distal water for 24 hours at 37°C beforetesting. For thermo cycling test, specimen were thermo cycled in thermo cyclingdevice. Bonding strength test was done using INSTRON universal testingmachine.Results: reinforcement of acrylic denture base with nano-fillers was significantlyincrease both tensile and shear bonding of lining material and thermo cyclingdecreases both bonding strength.Conclusion: reinforcement of acrylic denture base with nano fillers could improvebonding strength of lining material, while thermo cycling had a deleterious effecton bonding strength.


Article
The Correct Rules for Facades Stone Lining
ألاساليب الصحيحة لاستخدام مادة الحجر في تغليف الواجهات

Author: Dr. Ali Hussein Khudhair د. علي حسين خضير
Journal: JOURNAL OF MADENAT ALELEM COLLEGE مجلة كلية مدينة العلم الجامعة ISSN: 2073,2295 Year: 2018 Volume: 10 Issue: 2 Pages: 289-306
Publisher: City College of Science University كلية مدينة العلم الجامعة

Loading...
Loading...
Abstract

The aim of this research is directed to investigate the local and national process of stone lining for building facades to determine the drawbacks associated with local implementation of stone lining compared with national one ; and to suggest rules to overcome existing drawbacks resulting meanly ; from the absence of clear rules for lining and lack of standard stone lining supports in addition to failure of existing non standard support due to action of corrosion resulting in dangerous collapse of stone lining .In this research, implementation rules , support means act as part of the structure and water proofing are suggested

يهدف هذا البحث الى استقصاء عملية تنفيذ الانهاء بمادة الحجر في تغليف واجهات الابنية المتبعة محليا وعالميا وتحديد السلبيات والماخذ التي ترافق اسلوب التنفيذ المحلي مقارنة باسلوب التنفيذ المتداول عالميا مع اقتراح الحلول المناسبة لتجاوزهذه السلبيات والتي من اهمها عدم وجود اسلوب واضح للتنفيذ وعدم استخدام وسائل اسناد وتثبيت مصممه خصيصا لهذا النوع من العمل كما معمول به عالميا اضافة الى تعرض الوسائل المستخدمة محليا غير المؤهلة لفعل الامطار والرطوبة مؤديا الى تاكسدها وتاكلها بمرور الزمن وانهيار التغليف الذي ينتج عنه مخاطر بالغة. لقد تم اقتراح وسيلة وطريقة تنفيذ لهذه الوسيلة لتكون جزءا من الجزء الحامل مع الاخذ بنظر الاعتبار عزل الرطوبة


Article
Evaluation of the tensile bond strengths of heat cure acrylic and Valplast with silicone self cure soft liner

Author: Ali J. Abdulsahib علي عبد الصاحب
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: special issue 2 Pages: 5-9
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

Background: Soft lining materials have a key role in modern prosthodontics because of their capability of restoringhealth of inflamed and distorted mucosa. Gradual changes of oral tissues require that complete or partial denturesbe relined to improve their adaptation to the supporting tissue. This study aimed to evaluate the tensile bondstrength of heat cure acrylic and Valplast denture base materials to silicone self-cure soft lining material stored inartificial saliva.Materials and method: Two types of self cured silicone soft lining material (one with prime the other without prime oradhesive) applied to polymethylmethacrylate and injection-molded nylon denture base materials for tensile bondstrength testing using Instron machine.Results: The comparison between all test groups after (48) hours immersion in artificial saliva were highly significantly different fromeach other except for the comparison between groups PSP and VSP in which theirmeans were non-significant. After (12) weeks,the comparison between all test groupswere highly significantly different fromeach otherwhen compared statistically.Conclusion: This study indicated that prime (adhesive) increase the bond strength of the silicone soft lining materialswith denture base materials. Silicone soft lining materials are affected by artificial saliva storage


Article
Artificial Groundwater Recharge in Iraq through Rainwater Harvesting (Case Study)
التغذية الاصطناعية للمياه الجوفية في العراق من خلال حصاد مياه الأمطار (دراسة ميدانية)

Author: Ibtesam R. Kareem
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 6 Part (A) Engineering Pages: 1069-1080
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

Groundwater is considered as an important source of water supply in Iraq, so it is need replenishing by any way of recharging. The most important way for recharging the groundwater is by rainwater harvesting. The part of rainfall which losses as surface runoff can be store during the monsoon in collecting reservoirs (such as ponds or tanks) and use it when required. This study deals with the way of harvesting rainwater that falls on the land for the replenishment the groundwater and use it in the dry seasons. According to availability of recommended potential for successful artificial recharge projects, a site was selected in the Jolak basin north of Karkuk city, north of Iraq. The area is about 400 km2. Since the occurrence of rainfall in the north of Iraq is mostly limited to about five or six months in a year, so the recharge to ground water reservoir is restricted to this period only. The surplus rainwater is assumed to be collected in the several suggested collecting rectangular ponds to catch monsoon rains (storing a fraction of runoff). This water can then be diverted to the aquifer through recharge wells (which already exist in the study area) and replenish falling groundwater table by pumping the stored water. Ponds need to be lined to stop water from seeping out. Plastic lining has proved to be appropriate mainly because of low cost and reliability of the material , so it is suggested to be use in the lining of the ponds. Also the ponds are suggested to be cover during groundwater recharging in order to stop water from being lost into the air by evaporation. A computer software known as Groundwater Molding System (GMS) has been used in the present study to simulate the water conveyance from the collecting ponds to the underground reservoirs by wells. Results indicated that movement of surface water into the groundwater was predominantly an effective process. It can be shown also, that collecting ponds were a key driver of surface water into the subsurface along the study area.

تعتبر المياه الجوفية مصدرا هاما لتوفير المياه في العراق، لذا فهو بحاجة إلى التجديد بأية وسيلة من رة العواصف المطرية. وهناوسائل التغذية. من الطرق المهمة في تغذية المياه الجوفية هو حصاد مياه الأمطار لتخزين المياه خلال فتك العديد من الطرق لحصاد مياه الأمطار كتخزينها في خزانات سطحية مثل الاحواض أو خزانات تحت الأرض يجعلها متاحة للاستخدام عند الحاجة. هذه الدراسة تتعامل مع طريقة حصاد مياه الأمطار لتجديد موارد المياه الجوفية واستخدامها في مواسم الجفاف. وفقا لتوافر الإمكانات اللازمة لنجاح مشاريع التغذية الاصطناعية، تم اختيار موقع حوض جولاك شمال مدينة كركوك، شمال العراق. مساحة المنطقة تقدر ب 400 km2. يقتصر تساقط الأمطار في شمال العراق بنحو خمسة أو ستة أشهر في السنة، لذلك تقتصر تغذية خزانات المياه الجوفية لهذه الفترة فقط. تم اقتراح حفر مجموعة احواض لجمع مياه الامطار (تخزين جزء من الجريان السطحي). و تحويل هذه المياه إلى طبقة المياه الجوفية من خلال آبار التغذية (التي توجد بالفعل في منطقة الدراسة) وتجديد هبوط منسوب المياه الجوفية عن طريق الضخ من المياه المخزنة. كما تم اقتراح تبطين الاحوض بغشاء من البلاستيك نظرا لموثوقية اداء هذه الاغشية وتكاليفها المنخفضة .ولغرض منع تبخر المياه من سطح الاحواض تم اقتراح تغطية الاحواض باغشية بلاستكية اثناء عملية تغذية المياه الجوفية (اثناء الضخ) .وقد تم استخدم برنامج الحاسبة الجاهز والمسمى (GMS) في هذه الدراسة لمحاكاة نقل المياه الخزونة في احواض التجميع الى الخزانات الجوفية عن طريق الابار. وأشارت النتائج المستحصلة أن حركة المياه السطحية إلى المياه الجوفية عملية فعالة. و أن الاحواض هي الدافع الرئيسي للمياه السطحية في باطن الأرض على طول منطقة الدراسة.

Listing 1 - 10 of 13 << page
of 2
>>
Sort by
Narrow your search

Resource type

article (13)


Language

English (10)

Arabic (3)


Year
From To Submit

2018 (1)

2017 (2)

2016 (1)

2015 (1)

2013 (4)

More...