Sharif Digital Repository

In this study, a new method is proposed to evaluate the utility harmonic impedance and the harmonics responsibilities at the point of common coupling. The former task is accomplished by involving the harmonic phase angles in the data correlation method, and the latter one is done using an approach based on the fluctuation of the background harmonic voltage. An important advantage of the method is to take the load harmonic impedance into account in appropriate manner. The performance of the proposed method is verified using simulation studies for different cases and also field measurements. Long-term measurement data are used to determine the harmonic contribution of the industrial customers... 

The present study demonstrates numerically a novel approach to perform a controllable single-mode random laser, using stimulated Raman gain. Due to the narrow linewidth of the Raman line shape, only one of the modes of the passive random system can lase. The robust control on the emission spectrum was achieved through the selection of any desired quasi-modes, by adjusting the pump wavelength in order to place the center of Raman line shape on desired quasi-modes. This approach was proved using a developed nonlinear transfer matrix method for a 1D Raman random system. The proposed method includes the Raman gain saturation and the frequency-dependent index of refraction  

In this paper, two-axis dielectric laser acceleration is proposed by introducing a dual-grating base laser accelerator structure excited with two orthogonal propagating ultrashort laser pulses. A 2D periodic structure is designed that provides phase synchronicity between the relativistic particle beam and orthogonal propagating laser pulses. In this way, the particle beam can gain energy from both laser pulses simultaneously. It is numerically demonstrated that utilizing this method increases both the acceleration gradient and acceleration factor up to90%in comparison with dual-grating dielectric laser acceleration. Also, deflecting force elimination, particle beam quality, and bunch... 

In this paper, a periodic structure of different dielectric layers is proposed and investigated for relativistic electron acceleration. The periodic dielectric structure provides an accelerating electric field inside the structure. Results show that the electron beam can experience a strong electric force in one direction during propagation in the structure, leading to the acceleration gradient increasing by more than double in comparison with dual-grating structures. Acceleration gradient enhancement occurs without increasing the electric field much inside the structure; therefore, the maximum achievable acceleration gradient and acceleration factor are increased by more than 100%, reaching... 

For multiple testing problems, Benjamini and Hochberg (1995) proposed the false discovery rate (FDR) as an alternative to the family-wise error rate (FWER). Since then, researchers have provided many proofs to control the FDR under dierent assumptions. Storey et al. (2004) showed that the rejection threshold of a BH step-up procedure is a stopping time with respect to the reverse filtration generated by the pvalues and proposed a new proof based on the martingale theory. Following this work, martingale methods have been widely used to establish FDR control in various settings, but have been primarily applied to reverse filtration only. However, forward filtration can be more amenable for... 

With the expansion of electricity networks, increasing operational complexities, improved knowledge of the system operators, all with the subsidies elimination in some countries such as Iran and experiencing the real price of electricity by then, it necessitates a more reliable power to be delivered to the system customers. Power system automation is regarded as an efficient solution and the effective key to this problem. However, the great number of substations in power distribution systems has led to the fact that it is neither feasible nor economic to automate all of them. This calls for a comprehensive scheme on the placement of the distribution substations to be automated. In this... 

Large Language Models (LLMs) have emerged as the dominant paradigm in Natural Language Processing owing to their remarkable performance across various target tasks. However, naively fine-tuning them for specific downstream tasks often requires updating a vast number of parameters, resulting in high computational costs and overfitting when training data is limited. In this paper, we propose a novel approach, called Stochastic Tuning, that addresses these challenges by selectively updating a small subset of parameters in each step of the tuning process. Our approach is characterized by its customization of updates based on task-specific partial gradients with respect to stochastic... 

This work presents a new signaling method operating based on a Nyquist-rate orthogonal pulse amplitude modulation (NOPAM) scheme for high-speed wireline communication systems. The proposed signaling approach provides a 2 bit/symbol throughput like PAM-4 signaling while requiring only three voltage levels for data transmission. Thus, it is less sensitive to non-idealities of the lossy interfaces in long/medium reach links. A transceiver (TRx) architecture using NOPAM signaling is presented and realization of its main blocks is described. A 56 Gbps NOPAM TRx using a medium-reach link with 20 dB loss at 14 GHz is modeled and simulated in MATLAB. Performance of the system is provided and...