In this work, the possibility of a multiwavelength mode-locked fiber laser generation based on Four-Wave Mixing (FWM) induced by Fe2O3-SiO2 nanocomposite material is investigated for the first time. A multiwavelength mode-locked pulses fiber laser are generated from Ytterbium–doped fiber laser (YDFL) due to the combined action of high nonlinear absorption and high refractive coefficients of Fe2O3-SiO2 nanocomposite incorporated inside YDFL ring cavity. Up to more than 20 lasing lines in the 1040–1070 nm band with an equally lines separation of ~0.6 nm have been observed by just simple variation of passive modulation of the state of the polarization and the pump power altogether. Moreover, a passively mode-locked operation of YDFL laser has been realized with repetition rate of 18.75 MHz and pulse width of 10 ps. The proposed laser offers excellent long-standing stability with the average amount of optical signal/noise ratio of more than 41 dBm. Our study may pave a novel technique to generate multiwavelength lasing from fiber laser with the assistance by nanocomposite disordered media at low threshold pumping.
In this work, spinel ferrites (NiCoFe2O4) were prepared as thin films by dc reactive dual-magnetron co-sputtering technique. Effects of some operation parameters, such as inter-electrode distance, and preparation conditions such as mixing ratio of argon and oxygen in the gas mixture, on the structural and spectroscopic characteristics of the prepared samples were studied. For samples prepared at inter-electrode distance of 5 cm, only one functional group of OH- was observed in the FTIR spectra as all bands belonging to the metal-oxygen vibration were observed. Similarly, the XRD results showed that decreasing the pressure of oxygen in the gas mixture lead to grow more crystal planes in the samples prepare
... Show MoreABSTRACT The present study was conducted to determine the mode of presentation of hypothyroidism in pediatric patients and the effects of timing of diagnosis and therapy on the patient’s outcome. The study involved review and evaluation of the medical records of 41 registered patients in the Endocrine clinic of Children Welfare Teaching Hospital in Baghdad during the period from January 1991 to July 2007. Forty one patients included in this study. Twenty four (58.5%) were males and17 (41.4%) were females with a male to female ratio of 1.4:1, their age range is 40 days to12.3 years. The majority of the studied patients were infants 19(47%). The most commonly observed presenting features were growth retardation and short stature. The best t
... Show MoreA metal mandrel was designed for manufacturing the cathodes of high power electron tube ( Tetrode ) used in broadcasting transmitting tubes type TH558 and CQS200.The cathodes were manufactured in the present work from thoriated tungsten wires ( 2? ThO2- W) with different diameters .These cathodes were carbonized in sequences of processes to determine the carbonization parameters (temperature, pressure, time, current and voltage).Then the carbonized cathodes dimension were accurately measured to determine the deviation due to the high temperature distortion effect at about 1800°C .the distorted cathodes due to the carbonization process was treated when it was subjected inside the vacuum chamber and heat treated again .The carbonized cat
... Show MoreThe control of an aerial flexible joint robot (FJR) manipulator system with underactuation is a difficult task due to unavoidable factors, including, coupling, underactuation, nonlinearities, unmodeled uncertainties, and unpredictable external disturbances. To mitigate those issues, a new robust fixed-time sliding mode control (FxTSMC) is proposed by using a fixed-time sliding mode observer (FxTSMO) for the trajectory tracking problem of the FJR attached to the drones system. First, the underactuated FJR is comprehensively modeled and converted to a canonical model by employing two state transformations for ease of the control design. Then, based on the availability of the measured states, a cascaded FxTSMO (CFxTSMO) is constructed to estim
... Show MoreKaolin/Gum Arabic nanocomposite was cheaply synthesized from Kaolin and Gum Arabic. The Kaolin/Gum Arabic nanocomposite suspension, Gum Arabic extracts and Kaolin suspension were applied as antifungal agents. The antifungal activity was tested using agar well diffusion method where by wells were made on the petri dishes with cork borer 6mm diameter in size and various concentrations (150 µg/L, 200 µg/L, and 250 µg/L) of Gum Arabic ethanol extracts, Gum Arabic /Kaolin nanocomposite, and Kaolin was propelled into the wells with the help of micropipette and the petri dishes were allowed to stand for 30 minutes to ensure proper diffusion before being incubated at 37oC. The results showed that synthesized Kaolin/Gum Arabic nanoc
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Faces of the individual in his life many stressful events, which includes expertise undesirable, and events may involve a lot of sources of tension and the risk factors and threats in all areas of life, and this would make the stressful events play a role in the genesis of many diseases physical.
The high blood pressure is one of the most Actual manifestations of mental stress in the present scale physical disorders which may frequently in men relative to women, which may be caused by spasms in the blood vessels.
The study of biomechanical indicators in the arc of the run and the upgrading stage is one of the important variables that affect the nature of the upgrading and thus affect the result of the race due to the importance of these stages and the consequent variables during the last steps. That’s why, the jump-trainings based on assistant means or body weight positively affect the step-time for each of the three steps in the acceleration arc. As well as, it focuses on the momentary strength of each step at this stage. It also significantly affects the speed of motor performance to suit the activity in which the runner needs to perform perfect steps with high flow in order to convert the horizontal speed to a vertical one. This is achieved thr
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