Abstract: In this work we demonstrate and investigate the optical pulse propagation in a photonic band gap fiber Bragg grating (FBG). The light propagates in opposite direction in FBG is explained and discussed by a Coupled Mode Theory (CMT). The photonic band gap (stop band gap) is created by fabricated, a Bragg grating in optical fiber. The results show the pulse spectrum falls entirely within the stop band gap, the entire pulse is reflected by the grating, while when the pulse spectrum is outside the stop band gap the pulses will transmitted through the grating. The group velocity (VG) becomes zero at the edges of the stop band and group velocity dispersion β2 is anomalous on the shorter side of stop band gap whereas β2 for uniform fiber becomes anomalous for wavelengths lower than the zero dispersion.
Pure and doped TiO 2 with Bi films are obtained by pulse laser deposition technique at RT under vacume 10-3 mbar, and the influence of Bi content on the photocvoltaic properties of TiO 2 hetrojunctions is studied. All the films display photovoltaic in the near visible region. A broad double peaks are observed around λ= 300nm for pure TiO 2 at RT in the spectral response of the photocurrent, which corresponds approximately to the absorption edge and this peak shift to higher wavelength (600 nm) when Bi content increase by 7% then decrease by 9%. The result is confirmed with the decreasing of the energy gap in optical properties. Also, the increasing is due to an increase in the amount of Bi content, and shifted to 400nm when annealed at 523
... Show MoreAflatoxin B1 (AFB1) is a mycotoxin produced mainly by fungi Aspergillus flavus in food and animals feed. It is considered as a carcinogenic toxin for human and animals. The current study is designed to investigate the incidence of mycoflora in twenty four samples of local stored maize collected from Iraqi governorates; investigate the presence of aflatoxin B1 on these samples using TLC and ELISA techniques. The fungi recovered from maize samples were Aspergillus flavus (18.57 % ), Fusarium spp. (12.8 % ), A. ocraceus (9.96 % ) , A. terrus (9.07 % ), A. fumigatus (8.46 % ) , Alternaria spp. (6.40 % ) Rhizopus spp. (4.98 % ), A. niger spp., A. oryzae spp. (4.80 % ), Penicillium spp. (4.53 %) A. versicolor spp., Rhizoctonia spp. (4.27 %), A
... Show MoreAphelenchus avenae was isolated from the wheat crown in Summel distract- Duhok, Kurdistan region-Iraq infected by a crown rot disease which is caused by Fusarium spp; wheat's crown culturing on Potato Dextrose Agar (PDA) and incubating at 25°C A. avenae was found associated with fungal culture which meant that fungal nematode was parasitic on crown rot fungi on wheat crown, this species was described for the first time in Iraq.
Fungal Nematode incubated with Fusarium graminearum, F. oxysporum and Verticillium dahliae reproduce in both solid and liquid media, best results of nematode reproduction were recorded on F. graminearum followed by F. oxy
... Show MoreMetal nanoparticles (NPs) of silver (Ag), copper (Cu), zinc oxide (ZnO), cadmium oxide (CdO) and tin (Sn) were synthesized by laser ablation of a solid target in de-ionized water (DI). X-ray diffraction patterns showed the formation of AgO, Ag, Cu, ZnO, CdO, and Sn NPs. Absorbance spectrum of the produced nanoparticles was measured by UV-Vis spectrophotometer which showed that Ag and CdO NPs shifted to the short wavelength (blue shift), indicating the formation of NPs with smaller sizes, whereas CuO showed the formation two peaks. ZnO and Sn NPs shifted to the long wavelength (red shift) which indicates the formation NPs with larger size. Zeta potential results proved that ZnO nanoparticles were more stable (-26.53mV) than the othe
... Show MoreInterest has largely centered on the use of plant fibers to reinforce plastics, because these fibers are abundant and cheap. Carrot fibers (Curran) have been extracted from carrot, left over from carrot juice manufacture. The fibers of two sizes fine (50<µm) and coarse (100-150 µm) have been mixed with epoxy in four levels of loading (10, 20, 30, 40 wt %) respectively. Impact test, shore d hardness test and three point bending test of epoxy and carrot fiber-epoxy composites samples have been determined. The impact strength values of samples prepared with fine and coarse fibers increased as compared with pure epoxy sample. Hardness values increased, and the Young’s modulus values decreased with fiber content of both sizes.
The aim of this work is to study the influence of the type of fiber glass –mat on fatigue behavior of composite material which is manufactured from polyester and E-glass (woven roving, chopped strand mat (CSM)) as a laminate with a constant fiber volume fraction (VF) of 33%. The results showed that the laminates reinforced with E-glass (woven roving) [0/90, ±45.0/90] and [0/90, CSM, 0/90] have lower fatigue strength than the laminates reinforced with E-glass [0/90]3,[CSM]3 and [CSM, 0/90, CSM] although they had different tensile strength; the best laminate was [0/90]3 .
The duration of sunshine is one of the important indicators and one of the variables for measuring the amount of solar radiation collected in a particular area. Duration of solar brightness has been used to study atmospheric energy balance, sustainable development, ecosystem evolution and climate change. Predicting the average values of sunshine duration (SD) for Duhok city, Iraq on a daily basis using the approach of artificial neural network (ANN) is the focus of this paper. Many different ANN models with different input variables were used in the prediction processes. The daily average of the month, average temperature, maximum temperature, minimum temperature, relative humidity, wind direction, cloud level and atmosp
... Show MoreIn this research, the mechanism of cracks propagation for epoxy/ chopped carbon fibers composites have been investigated .Carbon fibers (5%, 10%, 15%, and 20%) by weight were used to reinforce epoxy resin. Bending test was carried out to evaluate the flexural strength in order to explain the mechanism of cracks propagation. It was found that, the flexural strength will increase with increasing the percentage weight for carbon fibers. At low stresses, the cracks will state at the lower surface for the specimen. Increasing the stresses will accelerate the speed of cracks until fracture accorded .The path of cracks is changed according to the distributions of carbon fibers