مقالههای Akbar Heydari
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
۱Determining the Parameters of Chirp Signal Using Cyclostationary Method in Presence of the Undesired Signal
اطلاعات انتشار: کنفرانس بین المللی پژوهش در علوم و تکنولوژی، سال ۱۳۹۴
تعداد صفحات: ۹
This paper deals with the problems of detecting a chirp signal of motion target against a strong undesired signal from the transmitter in radar. We use Generalized Almost–Cyclostationary (GACS) signal processing method to determine the rate and initial frequency of the chirp signal in presence of the strong undesired signal. This technique which exploits the second order cyclostationary to detect features of the chirp signal in low SNR has desirable properties. The study utilized a method to determine and characterize signals for highly adverse signal to interference plus noise and explain how using cyclostationary properties can extract features of chirp signal from the mixture received signal. The theory and simulation of this method indicated that the chirp rate depends on the lag parameter and the cycle frequency.<\div>
۲Parameter Estimation for FM Signals in Two Stage: Non Uniform Fast Fourier Transform (NUFFT) and Short–Time –Frequency Transform (STFT)
اطلاعات انتشار: دومین کنفرانس بین المللی پژوهش در علوم و تکنولوژی، سال ۱۳۹۴
تعداد صفحات: ۹
This study deals with estimating the parameters of the received signal of the poly phase in three orders. The process of estimation occurs in two stages: in the first stage, the high orders of the signal were estimated highly accurately using the Non Uniform FFT. The received signal passes through the componential match filter which has been estimated highly accurately. As it passes through this filter, the order of the ploy phase decreases. In the second stage, the components of the low order of the ploy phase signal are estimated highly accurately using the Short Time Frequency Transform (STFT) method. Finally, the findings of the stimulation in these two stages indicated the efficiency of the presented algorithm for the received signal parameters including the initial frequency, the chirp rate, and the change chirp rate<\div>
۳Simple and Rapid Immobilization of Firefly Luciferase on Functionalized Magnetic Nanoparticles; a Try to Improve Kinetic Properties and Stability
اطلاعات انتشار: Biomacromolecular Journal، اول،شماره۱، Summer ۲۰۱۵، سال ۰
تعداد صفحات: ۹
We expressed and purified a recombinant P. pyralis luciferase with N–terminal His–tags. The silanized Ni or Cu–loaded magnetic particles were prepared and used to assemble the His–tagged P. pyralis luciferase. This enzyme immobilized on functionalized magnetic nanoparticles (MNPs) via electrostatic interactions of His–tag with Ni2+\Cu2+ ions on the surface of MNPs using simple one step method. These particles were also used for purification of recombinant luciferase from crude extract of cell lysate. Effect of incubation time and amount of MNPs in bioluminescent activity were investigated to determine optimum condition for immobilization. Several properties of immobilized luciferase were studied and compared with free enzyme. Immobilization has shown different effects on Km for ATP and luciferin. In both immobilized form, Km(ATP) was increased while Km(luciferin) was shown decreases. Optimal temperature of both immobilized luciferase increased to 30 ºC while thermal stabilities have not shown significant differences compared to free enzyme. Both immobilized form inactivated after five consecutive reaction cycles.
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