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排序方式: 共有419条查询结果,搜索用时 15 毫秒
1.
Sadeghi-Kohan Somayeh Hellebrand Sybille Wunderlich Hans-Joachim 《Journal of Electronic Testing》2021,37(5-6):715-728
Journal of Electronic Testing - Safety-critical systems have to follow extremely high dependability requirements as specified in the standards for automotive, air, and space applications. The... 相似文献
2.
Naderi Sonia Khosroazad Somayeh Abedi Ali 《International Journal of Wireless Information Networks》2022,29(3):240-249
International Journal of Wireless Information Networks - With exponential growth in the number of wireless devices and limited available spectrum, the problem of spectrum sharing remains in... 相似文献
3.
Pooria Varahram Somayeh Mohammady Borhanuddin Mohd Ali 《Wireless Personal Communications》2013,72(2):1125-1137
Peak-to-average power ratio (PAPR) is one of the main drawbacks in orthogonal frequency division multiplexing (OFDM) systems. High PAPR forces the power amplifier to back off in order to operate in its linear region, which degrades the power efficiency of the system. Several PAPR reduction techniques have been developed, but most of them have not considered both complexity and PAPR reduction. In this paper, a novel PAPR reduction scheme based on the insertion of dummy sequences to an enhanced partial transmit sequence is proposed. By applying this scheme the PAPR performance is enhanced compared to the conventional methods while the complexity is significantly reduced. Numerical analysis is carried out with OFDM signal and QPSK modulation. 相似文献
4.
Hosein Morshedi Mosayeb Naseri Mohammad Reza Hantehzadeh Seyed Mohammad Elahi 《Journal of Electronic Materials》2018,47(4):2290-2297
In this paper, using a first principles calculation, a two-dimensional structure of silicon-antimony named penta-Sb\(_{2}\)Si is predicted. The structural, kinetic, and thermal stabilities of the predicted monolayer are confirmed by the cohesive energy calculation, phonon dispersion analysis, and first principles molecular dynamic simulation, respectively. The electronic properties investigation shows that the pentagonal Sb\(_{2}\)Si monolayer is a semiconductor with an indirect band gap of about 1.53 eV (2.1 eV) from GGA-PBE (PBE0 hybrid functional) calculations which can be effectively engineered by employing external biaxial compressive and tensile strain. Furthermore, the optical characteristics calculation indicates that the predicted monolayer has considerable optical absorption and reflectivity in the ultraviolet region. The results suggest that a Sb\(_{2}\)Si monolayer has very good potential applications in new nano-optoelectronic devices. 相似文献
5.
This paper presents a novel low-power majority function-based 1-bit full adder that uses MOS capacitors (MOSCAP) in its structure. It can work reliably at low supply voltage. In this design, the time-consuming XOR gates are eliminated. The circuits being studied are optimized for energy efficiency at 0.18-μm CMOS process technology. The adder cell is compared with seven widely used adders based on power consumption, speed, power-delay product (PDP) and area efficiency. Intensive simulation runs on a Cadence environment and HSPICE show that the new adder has more than 11% in power savings over a conventional 28-transistor CMOS adder. In addition, it consumes 30% less power than transmission function adder (TFA) and is 1.11 times faster. 相似文献
6.
Sakineh Meshkani Mahmood Ghoranneviss Mansoureh Lafouti Ahmad Salar Elahi 《Journal of Fusion Energy》2014,33(6):619-626
In this paper we presented experimental investigation of effects of local limiter biasing (Vbiasing = +200 v, Vbiasing = +320 v) on the plasma parameters as plasma current, loop voltage, poloidal beta, plasma pressure, plasma energy, plasma resistance, plasma temperature, plasma displacement, Shafranov parameter and plasma internal inductance in IR-T1 tokamak. For these purposes, array of magnetic probes and also a diamagnetic loop have been used. The results show that applied biased voltage Vbiasing = +200 v causes to decrease of about 40 % in plasma internal inductance. The plasma resistance and the plasma displacement have been decreased by Vbiasing = +200 v. The main result of the application of Vbiasing = +200 v is flatting the plasma parameters profiles. In other words, the addition of biasing voltage Vbiasing = +200 v to plasma could be effective for improving the quality of tokamak plasma discharge by creating the steady state plasma. The plasma current, plasma pressure, plasma energy, plasma temperature and shift parameter have increased after the application of limiter biasing with Vbiasing = +320 v but they decrease rapidly. 相似文献
7.
The time-resolved frequency component analysis has been performed using short time Fourier transform. Fourier-based techniques and auto-correlation have been employed to analyze the frequency of the MHD fluctuations. The time evolution of potential fluctuation, and electric field and turbulent transport have been measured by using two arrays of the Langmuir probes in both the radial and poloidal directions. The experiments have been done in different regimes as Limiter biasing and RHF and both of them. The analyses have been done by the fast Fourier transport (FFT) method and spectral features of them are obtained with the help of the standard auto-correlation technique. The results show that radial turbulent transport decreases about 60 % after positive biasing application while it increases about 40 % after negative biasing. The effect of positive biasing on poloidal turbulent transport displays an increase of about 55 % while the negative bias voltage decreases the poloidal turbulent transport about 30 %. Consequently, confinement is improved and plasma density rises significantly due to the applied positive biasing in IR-T1. But the results are reversed when negative biasing is applied. Also, in this work, the results of applied RHF (L = 3) are compared with biasing results and analysed. 相似文献
8.
E × B velocity shear effects on the plasma confinement were investigated in the IR-T1 tokamak. The investigations have been done at the presence of external applied electric and Resonant Helical magnetic Fields (RHF). In this work, experimental data have been measured by using two arrays of the Langmuir probes in both the radial and poloidal directions. A velocity shear stabilization mechanism has also been proposed to be responsible for an improvement in plasma confinement. The results show that Er × B drift velocity (VE×B) reduces about 90 % due to applied biasing and RHF at edge plasma. We have also observed that positive biasing and RHF lead to a significant decrease (>80 %) for radial turbulent transport (ΓE×B) at edge plasma. In this paper, the electrostatic Reynolds stress (Rs) and the shearing rate γE×B have been calculated. We have also compared the Rs and γE×B at presence of the biasing and RHF and without biasing and RHF. A good correlation between confinement modifications and Er × B velocity shear has been found suggesting that confinement enhancement originates at the edge plasma as a consequence of the formation of a particle transport barrier just inside the limiter. 相似文献
9.
The fact that the mean free path of an electron in plasma is a strongly increasing function of its velocity gives rise to the phenomenon of fast (high energy) electron production. In an electric field, electrons which exceed a critical velocity, for which the collisional drag balances the acceleration by the field, are accelerated freely and can reach very high energies. In low density tokamak discharges a considerable amount of these high energy electrons with energies up to tens of keV to MeV can thus be created. As these energetic electrons are effectively collision-less, they follow the magnetic field lines and can therefore been used to probe the magnetic turbulence in the core of the plasma. In this research, external electric field effects on the discharges which lead to this phenomenon were investigated. Tokamak limiter biasing is one of the methods for controlling the radial electric field and can induce a transition to an improved confinement state. 相似文献
10.
Ahmad Rahimirad M. Emami M. Ghoranneviss A. Salar Elahi 《Journal of Fusion Energy》2009,28(4):420-426
We have expressed two different methods to determine the plasma positions in the IR-T1 tokamak. An array of magnetic probes
are placed polidally outside the chamber surface and their signals are plugged in the displacement equation and horizontal
displacement of plasma column is obtained. The results of this measurement are compared with the experimental data obtained
from sensors of multipole moment. It was detected a fluctuation in plasma displacement obtained with discrete magnetic coils,
so the method of multiple moments is better than the discrete magnetic coils for the determination plasma displacement that
used for feed back control. 相似文献