Bragg Reflectors consist of periodic dielectric layers having an optical path length of quarter wavelength for each layer giving them important properties and makes them suitable for optoelectronics applications. The reflectivity can be increased by increasing the number of layers of the mirror to get the required value. For example for an 8 layers Bragg mirror (two layers for each dielectric pair), the contrast of the refractive index has to be equal to 0.275 for reaching reflectivity > 99%. Doubling the number of layers results in a reflectivity of 99.99%. The high reflectivity is purely caused by multiple-interference effects. It can be analyzed by using different matrix methods such as the transfer matrix method (TMM) which is the simplest method to study the characteristic of devices with different alternating layers.
The management of construction projects needs to complete the basics of system management and work. Starting from the idea and how to turn it into a full study and ended at the construction project completion arriving at the purpose prepared for it, so the projects need to control on its operation and integration system in order to succeed.
It is no secret for who concerned in construction projects field that the design stage is a very important stage in construction project because it determines the final features of the project through the requirements provided by the employer for the consultant to formulate it during this phase in the form of plans, drawings, and specifications, then translated on the ground as the shape of co
... Show MoreThe movement is considered one of the important factors which attracts the receiver attention in designing artificial works in general, and especially in the advertisements, moreover the subject of the movement in the designing advertisements needs more care and study by the scholars. From this importance and from reaching to the basic streams of the research topic (the effect of the movement in the graphic design) the problem of the research has been set according to the following wonder:
- What is the designing process that establishes the movement in the commercial advertisements designs?
The researche
... Show MoreIn this study the isomerization of desulfuerized light Iraqi petroleum naphtha (Al-Dura Refinery) with boiling point range of 37 to 124 °C , 80.5 API specific gravity and 68.2 octane number has been investigated. Two types of catalysts were prepared (Pt/HX and Pt/SrX) by impregnation of 0.8 wt% Pt on l 3X-zeolite. The catalyst activity and selectivity toward isomerization, and catalyst deactivation were investigated.
The isomerization unit consisted of a vertical tubular stainless steel reactor of 2 cm internal diameter, 3 cm external diameter and 68 cm height. The operating pressure was atmospheric for all experimental runs. The liquid flow of lightnaphtha was 0.4 Uh, and the catalyst weight was 50 gm, H/
... Show MoreThe present study illustrates observations, record accurate description and discussion about the behavior of twelve tested, simply supported, precast, prestressed, segmental, concrete beams with different segment numbers exposed to high fire temperatures of 300°C, 500°C, and 700°C. The test program included thermal tests by using a furnace manufactured for this purpose to expose to high burning temperature (fire flame) nine beams which were loaded with sustaining dead load throughout the burning process. The beams were divided into three groups depending on the precast segments number. All had an identical total length of 3150mm but each had different segment number (9, 7, and 5 segments), in other words, different segment length
... Show MoreThe aim of this paper is to present a method for solving high order ordinary differential equations with two point's boundary condition, we propose semi-analytic technique using two-point oscillatory interpolation to construct polynomial solution. The original problem is concerned using two-point oscillatory interpolation with the fit equal numbers of derivatives at the end points of an interval [0 , 1] . Also, many examples are presented to demonstrate the applicability, accuracy and efficiency of the method by comparing with conventional methods.
The effect of three high temperatures for five exposure periods on the developments of larvae, pupae and adults of Trogoderma granarium (Everts) and their biological performance were investigated. The results revealed that the percent of mortality was increased as the temperature and the exposure period increased, e. g. exposing last instar larvae to 45°C for 6 hrs caused 100% death of this stage, while exposing adults (1-3) days old to the same temperature and exposure time resulted in that these adults did not able to survive more than 24 hrs.; in addition, the results showed that the ability of reproduction of adults was depended on the temperature, duration of exposure and the sex.
Extension of bandwidth for high reflectance zone for the spectral region (8-14pm) was studied adapting the concept of contiguous and overlapping high reflectance stacks. Computations was carried out using the modified characteristic matrix theory restricted to near-normal incidence of light on dielectric , homogenous and isotropic symmetrical stack. Certain precautions must be taken in the choice of stacks to avoid deep —reflectance minima from developing within the extended high reflectance region. Results illustrate that the techniques of extending the high reflectance regions are applicable not only to mirrors , but also to short-and long-edge filter and to narrow band pass filters.
In this work, an anti-reflection coating was prepared in the region (400-1000) nm of wavelength, with a double layer of silicon dioxide (SiO2) as an inner layer and the second layer of the mixture (SiO2) and titanium dioxide (TiO2) with certain ratios, as an outer layer using the chemical spraying method with a number of 6 sprays of layer SiO2 and 12 sprays of layer SiO2 - TiO2. Using the method of chemical spraying deposited on the glass as a substrate with a different number of sprays of SiO2, and a fixed number of TiO2-SiO2. The optical and structural properties were determined using UV-Vis spectroscopy and atomic force mi
... Show MoreAbstract
Objective(s): To evaluate high school male students' knowledge about substance use, to determine the effectiveness of the education program on high school mal students' knowledge about substance use.
Methodology: A quasi-experimental (pre-posttest) design was carried out to determine the effectiveness of an educational program on knowledge of high school students about substance use in AL-Kut city. The study was started from 20th h September 2022 to 24th November 2022. The sample was non-probability (purposive sample) sample of (60) student were selected according to the study that are working in Al Kut Education Directo
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