Lasers, with their unique characteristics in terms of excellent beam quality, especially directionality and coherency, make them the solution that is key for many processes that require high precision. Lasers have good susceptibility to integrate with automated systems, which provides high flexibility to reach difficult zones. In addition, as a processing tool, a laser can be considered as a contact-free tool of precise tip that became attractive for high precision machining at the micro and nanoscales for different materials. All of the above advantages may be not enough unless the laser technician/engineer has enough knowledge about the mechanism of interaction between the laser light with the processed material. Several sequential phenomena occur when an intense laser beam is incident on the surface of a material. Heating, melting, vaporization and plasma formation are present in the normal interaction of an intense laser beam with matter. This may be followed by additional events such as acoustic and optical emissions, structure shockwaves, thermal effects, structural defects and residual stresses. The process is affected by a lot of variables that can transfer the interaction towards extremely different behavior in terms of colder and fewer side-effect interactions, which yield precise features for the processed material. The most crucial variables are the time scale of interaction and laser wavelength with respect to the properties of the processed material undertaken as well as the laser fluence. The objective of this chapter is to introduce the fundamentals of physical and mathematical concepts of laser and matter interaction and its dependency on different time scale regimes. Interaction with a short and ultra-short laser pulse has attracted a significant amount of interest in industry due to its huge impact in micro-/nanomachining applications.
The Frequency-hopping Spread Spectrum (FHSS) systems and techniques are using in military and civilianradar recently and in the communication system for securing the information on wireless communications link channels, for example in the Wi-Fi 8.02.X IEEE using multiple number bandwidth and frequencies in the wireless channel in order to hopping on them for increasing the security level during the broadcast, but nowadays FHSS problem, which is, any Smart Software Defined Radio (S-SDR) can easily detect a wireless signal at the transmitter and the receiver for the hopping sequence in both of these, then duplicate this sequence in order to hack the signal on both transmitter and receiver messages using the order of the se
... Show MoreThe research is an attempt to investigate experimentally the influence of teacher’s errors correction and students’ errors correction on teaching English at the College of Physical Education for Women. Errors are seen as a natural way for developing any language but teachers are puzzled the way they can correct these errors. So, this research gives some idea of using two types of errors correction. The sample of the research is female students of the first year stage at the College of Physical Education for Women of the academic year 2009-2010. The whole population of the research is (94) students while the sample is (64). Thus, the sample represents 68% from the population of the research. The sample represents It is hypothesized th
... Show MoreThis paper is submitted as anew approach to simulate manufacturing control & planning system to define the problem of designing control system on the needs for materials.
Production planning & control is a total and complex operation, resides in the essence of manufacturing companies operations. The successful process of production planning and control systems is critical for the staying of manufacturing organizations in markets leading to the increasing consumer competition and which dominate most of manufacturing sectors because of the market oriented economy , thus , what has happened previously , that the companies possessed a great inventory of crude material, components, and groupings and they use in flexible techni
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The current research aims to identify the effectiveness of social stories in increasing social interaction among children with an autism spectrum disorder. The researcher used the single-subject design methodology (Single Subject Designs, SSD) with
(A-B) design to answer the research questions. The study sample consisted of (3) children with autism spectrum disorder enrolled in a transit daycare center in the Asir region, Saudi Arabia. The results of the study showed that there is a positive functional relationship between social stories and play to increase social interaction among children with autism spectrum disorder, which contributed to the acquisition and generalization of this behav
... Show MoreIn this research, the degradation of Dazomet has been studied by using thermal Fenton process and photo-Fenton processes under UV and lights sun. The optimum values of amounts of the Fenton reagents have been determined (0.07g FeSO4 .7H2O, 3.5µl H2O2) at 25 °C and at pH 7 where the degradation percentages of Dazomet were recorded high. It has been found that solar photo Fenton process was more effective in degradation of Dazomet than photo-Fenton under UV-light and thermal Fenton processes, the percentage of degradation of Dazomet by photo-Fenton under sun light are 88% and 100% at 249 nm and 281 nm respectively, while the percentages of degradation for photo-Fenton under UV-light are 87%, 96% and for thermal Fenton are 70% and 66
... Show MoreIn this research, the degradation of Dazomet has been studied by using thermal Fenton process and photo-Fenton processes under UV and lights sun. The optimum values of amounts of the Fenton reagents have been determined (0.07g FeSO4 .7H2O, 3.5µl H2O2) at 25 °C and at pH 7 where the degradation percentages of Dazomet were recorded high. It has been found that solar photo Fenton process was more effective in degradation of Dazomet than photo-Fenton under UV-light and thermal Fenton processes, the percentage of degradation of Dazomet by photo-Fenton under sun light are 88% and 100% at 249 nm and 281 nm respectively, while the percentages of degradation for photo-Fenton under UV-light are 87%, 96% and for thermal Fenton are 70% and 66.8% at 2
... Show MoreThe purpose of this paper is to preparing preventive exercises supported by collagen supplements and vitamin D for handball players, and identify the effect of preventive physical exercises supported by collagen supplements and vitamin D on some physical and skill abilities of handball players. The researchers used the experimental method and designed two groups, one experimental and the other control, with both pre- and post-tests, to suit the nature of the research. The research community was selected from handball players (specialized school players), numbering (14), and they were divided into two groups, each group numbering (7) players. One of the most important results reached by the researcher is that: The exercises prepared by the r
... Show MoreThe researchers have recently noticed the interest in the problem of overweight and how to find solutions to it until it is now at the forefront in terms of innovating various and different methods and treatment methods, and the interest in developing health fitness is one of the most important requirements of physical activity for the trainees, which led to the multiplicity of sports activities that promote the health aspect For the individual, in addition to the aesthetic aspect, the problem lies in not adopting training programs according to codified scientific foundations aiming, in addition to reducing weight, to raise the general health level of the trainee participating in fitness institutes, as the trainers do not follow the
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