Under cyclic loading, aluminum alloys exhibit less fatigue life than steel alloys of similar strength and this is considered as Achilles's heel of such alloys. A nanosecond fiber laser was used to apply high speed laser shock peening process on thin aluminum plates in order to enhance the fatigue life by introducing compressive residual stresses. The effect of three working parameters namely the pulse repetition rate (PRR), spot size (ω) and scanning speed (v) on limiting the fatigue failure was investigated. The optimum results, represented by the longer fatigue life, were at PRR of 22.5 kHz, ω of 0.04 mm and at both v's of 200 and 500 mm/sec. The research yielded significant results represented by a maximum percentage increase in the fatigue life of 505.25% accompanied by the least deformation for the processed surfaces. SEM images for the specimens processed by the optimum process conditions imply no ablation has occurred at the surface, and the process is completely cold. X-ray diffraction analysis indicates a reduction in grains size, an increase of 28.56% in the lengths of dislocations and formation of effective compressive residual stress at the surface and beneath reaches to 700 μm.
In this work, a pulsed Nd:YAG laser(out put energy=5J and pulse
duration=300μsec) was used to perform drilling in samples of lead, stainless steel
304, brass, copper and aluminum. Laser irradiation was carried out in both air and
in a suitable chamber of controlled pressure inside. The effect of pressure inside the
chamber on the drilling process was investigated. Then, the chamber was filled with
argon gas to investigate its effect on drilling process where an enhancement in
drilling depth was observed compared to that in case of irradiation in air and
chamber of air pressure. As well, the effect of focus position on the process was
studied with the pressure varying inside the chamber in order to construct a
Vocational stresses and their relation with the level of ambition among the lecturers of the university In general , vocational stresses affect the attention and the process of focusing making individual busy with solving of his daily problems instead of his job. The vocational stresses , anxiety and tension are factors effecting the physical and psychological ability of the individual. This study aims to measure the vocational stresses among the lecturers of the university , to measure the level of ambition among them, to identify the statistical differences significant among them according to sex variable, to identify the differences significant in level of ambition among them according to sex variable and to identify the correlation r
... Show MoreThe rheological and fusion behavior of polyvinyl chloride (PVC) compounds plays a dominant role in
the processing operations and in the development of physical properties in the processed material. A
comprehensive study was made in this work to evaluate the effect of shear and thermal history on stability, mechanical and rheological properties of rigid PVC compounds. Different samples of Rigid Poly vinyl chloride including dry blend powder, granules, and bottles molded from both were examined. A study was also made on recycled RPVC where 25% of reclaimed material was continuously blended with fresh dry blend and processed for 15 cycles. Results showed that compaction of the PVC material took place in the brabender plastograph at co
This study focused on treatment of real wastewater rejected from leather industry in Al-Nahrawan city in Iraq by Electrocoagulation (EC) process followed by Reverse Osmosis (RO) process. The successive treatment was applied due to high concentration of Cr3+ ions (about 1600 ppm) rejected in wastewater of this industry and for applying EC with moderate power consumption and better results of produced water. In Electrocoagulation process (EC), the effect of NaCl concentration (1.5, 3 g/l), current density (C.D.) (15-25 mA/cm2), electrolysis time (1-2 h), and distance between electrodes (E.D.) (1-2 cm) were examined in a batch cell by implementing Taguchi experimental design. According to the results obtained from multiple regression and signa
... Show MoreThis research examines the factors which influence pedestrian's walking speed in Baghdad. the variations in walking speed of pedestrians are related to pedestrian characteristics such as gender, age group, and clothing traditions. Using the established methodology, the counts of pedestrians were performed using manual and video counting. The case study was performed in two streets located in a highly crowded commercial zone at the city center of Baghdad: Al-Karada Dakhel and Al- Sina’a Street. Data were subjected to statistical analysis using IBM SPSS Statistics 19 software. It has been found that Iraqi pedestrians walk slower than other pedestrians in the developed countries or in the region with minimum walking speed of 29.85 m/min.
... Show Moreيهدف البحث الى التعرف على تأثير تمرينات خاصة لتطوير القوة الانفجارية والقوة المميزة بالسرعة والتحمل اللاهوائي للاعبي كرة القدم ، واستخدمت الباحثتان المنهج التجريبي باستخدام القياس القبلي البعدي لمجموعتين احداهما تجريبية والأخري ضابطة ، واختيرت عينة البحث عمديا من الناشئين في أكاديمية سبانيول الاسبانية في العراق والبالغ عددهم 16 لاعباً . واستخدمت الاختبارات البدنية كوسائل وأدوات لجمع البيانات ومن أهم
... Show MoreMost species of Mollusca lives in salts water, on the shores of seas and lakes and some in fresh water, others are found in deserts, forests and forms and there are 45,000 species . They are invertebrate animals with lateral symmetry, slow-moving and a few of them are fast, like Octopus and Squid and some of them are economic importance. The class Gastropoda are considered the largest class belonging to the Phylum-Mollusca, as it contains more than 80%. Its importance follows from its great diversity and spread in all environments. It has an ecological importance because it plays an great role in ecosystems due to the diversity of its food methods between herbivorous and predatory. Studies on snails in Iraq are very few and modest. Hence
... Show MoreThe study aimed to explore the relationship between future anxiety and life orientation of male and female nurses, working in government hospitals of Gaza Strip governorates. The study sample consisted of 228 nurses (131 male nurses and97 female nurses. To achieve the study objectives , the researcher used the future anxiety scale, prepared by the researcher, and life orientation scale prepared by Scheier and Craver (1985 ) and translated into Arabic by Bader Al-Ansari . The results indicated that the level of future anxiety among nurses working at government hospitals was (64.85%), a high percentage, whereas life orientation was (65.96%), a low percentage. Additionally , the results showed that the Pearson correlation coefficient betwee
... Show MoreThis research deals with the aesthetics of describing nature and the joys of urban life in the environment of Fatimid Egypt, among a group of poets, who were deceived by its enchanting beauty and breathtaking scenery, through it they depicted the reality of the life they live, and the things that involved them, as well as showing their personal culture, and the joys of life that experience, articulating this with a descriptive and analytical study, focusing on how the poet portrayed the visual scene, in an important stage of Arabic literature in Egypt.
Objective(s): The present study describes the quality of life (QOL) among adolescents with age of (12-22) year old and identifies factors that may be associated with it. Methodology: A cross-sectional design is carried throughout to evaluate adolescents' quality of life in Hilla City for the period of September 2nd 2016 to November 6th 2016. The present study is conducted in different settings that include schools and colleges in Hilla City. A non-probability "purposive" sample of (144) participant is selected and comprised of (50%) males and (50%) females. An instrument is constructed for the intent of the st