In this work, results of a mathematical analysis of the role of workpiece preheating in laser keyhole welding were presented. This analysis considered the steady-state welding as well as certain range of boundary conditions over which preheating effect would be indicated. This work is an attempt to interpret the role of preheating to increase welding depth and perform keyhole welding with high quality using physical and thermal properties of steel alloys.

We report here the observation of 16 µm superradiance laser action generated from optical pumping of CF4 gas molecules (which is cooled to 140 Kº by a boil-off liquid-N2) by a TEA-CO2 laser 9R12 line. Output laser pulses of 7 mJ and 200 ns have been obtained.

Introduction: This study was performed to compare the effect of Fractional CO2 laser or Q switched Nd:YAG laser of surface treatment on the shear bond strength of zirconia-porcelain interface. Methods: Fractional CO2 laser at 30 W, 2 ms, time interval 1 ms, distance between spots 0.3 mm, and number of scans is (4) or Q switched Nd:YAG laser at 30 J/mm2 and 10 Hz were used to assess the shear bond strength of zirconia to porcelain. Pre-sintered zirconia specimens were divided into three groups (n = 10) according to the surface treatment technique used: (a) untreated (Control) group; (b) CO2 group; (c) Nd:YAG group. All samples were then sintered and veneered with porcelain according to the manufacturer’s instructions. Surface morph

Aim: To evaluate the commercial pure titanium disks that structuring by laser in two design (dot and groove) each one with three different laser scan (5, 15 and 25) and comparing with titanium surface that not subjected to any surface structuring (control) through measuring the wettability test and surface roughness test. Materials and methods: Structuring on the surface of the commercial pure titanium (CP Ti) disks was performed via using fiber laser CNC machine in two design (dot and groove) in three different laser scans (5, 15 and 25), then the structuring disks analyzed with the control group by atomic force microscope and water contact angle test. Results: The results of this study showed that the surface roughness and the wettability

The importance of research is to be considered by highlighting the tax policy in Iraq which extended for successive measurement of the amount of tax receipts for respective periods, the research problem represents security, economic and political issues that Iraq suffered which were very difficult since Nineties of the last century until now that led to a lake of clarity in tax policy trends, volatility in it and finally reflected on the tax revenues increase or decrease. One of the main recommendations of the research is: (The necessity to develop a deliberate strategy for tax policy in Iraq which should take into account financial, economic, and social goals in appropriate way).

اهمية البحث والحاجة اليه

      لم تعد التربية في الوقت الحاضر اعتباطا وتخبطا ، أنها علم وفن ، نظر وعمل ، اجتهاد وتطبيق ، اختصاص وابتكار والمربي ، أبا ، إما أو معلما أو زعيما أو مصلحا اجتماعيا ، أصبح بحاجة ماسة للاطلاع على التربية وفكرها التربوي والتعمق في أساليبها ووسائلها ( عاقل ، 1978 ،ص 3 ) .

    إن بناء المجتمع أو التربية ،لايمكن إن يكون لهوا ولعبا ، والحق إن بن

Stop the search on the performance of the stylistic literary messages sent by
Abu Mohammed Amer bin Said Altakrna to the kings of his time and Ullach
highlighting the method of the three levels is psychological and away the consignee
and the receiver Taster literary text.
Level voice and rhythmic, which dealt with (alliteration and Naturalization
voice, and repetition and parallelism, and rhyme and toning) and its impact on the
taste and the emotional art between the sender and the receiver Bashklah.
Who has studied the structural level (introductory sentence order methods in the
messages, generally have much style presentation and brief delays and actor, and
then end the moral and intellectual martyrdom and de

The world has seen and from our Arab significant changes as a result of scientific progress tremendous Born information revolution circulated individuals around the world via the Internet, have left traces extreme depth on their thinking and attitudes in spite of idiosyncrasies that characterize the communities in terms of their cultural, social and nature of education systems where, However, there were some aspects of transformation and change in various areas of life that had a direct impact on the construction of intellectual individuals, and which is no doubt that human beings look alike in respects morphological and biological see them disagree intellectually, everyone has ideas and values​​

The six names are names developed by grammarians, so some of them counted them as six, which are (your father, your brother, your father-in-law, Hanuk, Fuk, and Dhu). The Arabs, as explained by Sibawayh and the linguists after him, when this name was contrary to the conditions of grammar, and what we follow in the rules of these words is that they are expressed in letters that linguists call (vowels), while phonologists call them (long vowels), which are (alif, waw, Walia).