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The effect of random dopant fluctuation on threshold voltage and drain current variation in junctionless nanotransistors

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Journal of Semiconductors 2015年第9期36卷 20-25页

作者： Arash Rezapour Pegah Rezapour electrical engineering Department Faculty of EngineeringIslamic Azad University of Arak MSc Electrical Engineering DepartmentFaculty of EngineeringIslamic Azad University of Khomein

We investigate the effect of dopant random fluctuation on threshold voltage and drain current variation in a two-gate nanoscale transistor. We used a quantum-corrected technology computer aided design simulation to run the simulation （10000 randomizations）. With this simulation, we could study the effects of varying the dimensions （length and width）, and thicknesses of oxide and dopant factors of a transistor on the threshold voltage and drain current in subthreshold region （off） and overthreshold （on）. It was found that in the subthreshold region the variability of the drain current and threshold voltage is relatively fixed while in the overthreshold region the variability of the threshold voltage and drain current decreases remarkably, despite the slight reduction of gate voltage diffusion （compared with that of the subthreshold）. These results have been interpreted by using previously reported models for threshold current variability, load displacement, and simple analytical calculations. Scaling analysis shows that the variability of the characteristics of this semiconductor increases as the effects of the short channel increases. Therefore, with a slight increase of length and a reduction of width, oxide thickness, and dopant factor, we could correct the effect of the short channel.

关键词： junctionless transistor subthreshold region above threshold region short-channel effects fieldimpedance method

Assessing the Effectiveness of Solar Photovoltaic Powered Reverse Osmosis Desalination Systems across Different Water Resources in Saudi Arabia

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Open Journal of Modern Hydrology 2025年第1期15卷 1-17页

作者： O. S. Abd El-Kawi Mechanical engineering Department Faculty of Engineering Al-Baha University Al Baha Saudi Arabia Reactors Department Nuclear Research Center Egyptian Atomic Energy Authority Cairo Egypt

This study investigates the performance of a solar photovoltaic (PV)-powered reverse osmosis (RO) desalination system applied to diverse water sources in the Al-Baha region, Saudi Arabia, including seawater, groundwater, rainwater, municipal water, and brackish water. Key water quality parameters including Total Dissolved Solids (TDS), pH, electrical Conductivity (EC), salinity, and Specific Gravity (SG) were measured before and after desalination to assess system effectiveness. Results showed significant reductions in TDS, EC, and salinity levels across all water types, with seawater and brackish water achieving salt rejection rates of 98.32% and 99.16%, respectively. Post-desalination TDS for seawater decreased from 25,000 mg/L to 420 mg/L and for brackish water from 11,900 mg/L to 100 mg/L, achieving potable standards. pH values remained stable within potable standards, while EC values for seawater and brackish water dropped from 50,000 µS/cm to 484 µS/cm and from 12,000 µS/cm to 95 µS/cm, respectively. Water recovery rates varied from 70% to 95.33%, with the highest recovery observed in rainwater and groundwater samples. The overall desalination efficiency was highest for seawater and brackish water, at 82.96% and 84.5%, respectively, demonstrating the PV-RO system’s capability to provide high-quality, potable water from a variety of sources. This study underscores the potential of solar-powered RO technology as a sustainable solution for desalination in regions with diverse water sources and limited access to electricity.

关键词： Solar Photovoltaic (PV)-Powered Reverse Osmosis Water Sources

Power Quality Assessment of Voltage Positive Feedback Based Islanding Detection Algorithm

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Journal of Modern Power Systems and Clean Energy 2020年第4期8卷 787-795页

作者： Reza Bakhshi-Jafarabadi Reza Ghazi Javad Sadeh electrical engineering Department Faculty of EngineeringFerdowsi University of MashhadMashhadIran

Islanding refers to a condition where distributed generators(DGs)inject power solely to the local load after electrical separation from power *** islanding detection methods(IDMs)categorized into remote,active,and passive groups have been reported to detect this undesirable *** active techniques,a disturbance is injected into the DG’s controller to drift a local yardstick out of the permissible *** this disturbance leads to more effective detections even in well-balanced island,it raises the total harmonic distortion(THD)of the output current under the normal operation *** paper analyzes the power quality aspect of the modified sliding mode controller as a new active IDM for grid-connected photovoltaic system(GCPVS)with a string *** performance is compared with the voltage positive feedback(VPF)method,a well-known active *** evaluation is carried out for a 1 k Wp GCPVS in MATLAB/Simulink platform by measuring the output current harmonics and THD as well as the efficiency under various penetration and disturbance *** output results demonstrate that since the proposed disturbance changes the amplitude of the output current,it does not generate harmonics/***,it has a negligible adverse effect on power *** is finally concluded that the performance of the sliding mode-based IDM is reliable from the standpoints of islanding detection and power quality.

关键词： Islanding detection method(IDM) power quality sliding mode controller total harmonic distortion(THD) voltage positive feedback(VPF)

On selecting transmission mode for D2D transmitter in underlay cellular network with a multi-antenna base station

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Digital Communications and Networks 2022年第2期8卷 194-207页

作者： Wiroonsak Santipach Kaemmatat Jiravanstit Department of electrical engineering Faculty of EngineeringKasetsart UniversityBangkok10900Thailand

The Device-to-Device(D2D)communication underlaying cellular networks is considered in this *** D2D transmitter in the D2D mode can directly transmit messages to a receiver,but it may interfere with the transmission of another cellular user who shares the same uplink *** transmitter can also operate in a cellular mode in which no interference to another cellular user *** propose a mode selection scheme that aims to minimize the transmission power of the D2D transmitter subject to constraints on the minimum required data rate and maximum interference to other cellular *** proposed scheme is based on bounds for transmission power and is less complex than the optimal ***,it requires only a few statistics and does not need a fading channel *** performance of the scheme is close to optimum when the number of Base Station(BS)antennas is large,and the mean absolute deviation of the fading terms is *** verify this with numerical results of the Rician and Rayleigh fading channels by assuming that the BS antennas are *** simulation results for the two correlated BS antennas are presented herein.

关键词： D2D Transmission mode Cellular underlaying Multi-antenna base station Transmission power

Robust Optimal Higher-order-observer-based Dynamic Sliding Mode Control for VTOL Unmanned Aerial Vehicles

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International Journal of Automation and computing 2021年第5期18卷 802-813页

作者： Yashar Mousavi Amin Zarei Arash Mousavi Mohsen Biari Department of Applied Science School of ComputingEngineering and Built EnvironmentGlasgow Caledonian UniversityGlasgow G4 OBAUK Department of electrical and Computer engineering University of Sistan and BaluchestanZahedan ***Iran Department electrical engineering and Applied Sciences Paradise Research CenterJahrom ***Iran faculty of electrical and robotic engineering Shahrood University of TechnologyShahrood ***Iran

This paper investigates the precise trajectory tracking of unmanned aerial vehicles(UAV) capable of vertical take-off and landing(VTOL) subjected to external disturbances. For this reason, a robust higher-order-observer-based dynamic sliding mode controller(HOB-DSMC) is developed and optimized using the fractional-order firefly algorithm(FOFA). In the proposed scheme, the sliding surface is defined as a function of output variables, and the higher-order observer is utilized to estimate the unmeasured variables,which effectively alleviate the undesirable effects of the chattering phenomenon. A neighboring point close to the sliding surface is considered, and as the tracking error approaches this point, the second control is activated to reduce the control input. The stability analysis of the closed-loop system is studied based on Lyapunov stability theorem. For a better study of the proposed scheme, various trajectory tracking tests are provided, where accurate tracking and strong robustness can be simultaneously ensured. Comparative simulation results validate the proposed control strategy′s effectiveness and its superiorities over conventional sliding mode controller(SMC) and integral SMC approaches.

关键词： Unmanned aerial vehicle dynamic sliding mode trajectory tracking fractional firefly algorithm vertical take-off and landing system

Stabilization of a class of nonlinear discrete time systems with time varying delay

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Journal of Central South University 2014年第10期21卷 3769-3776页

作者： Maryam Fattahi Nastaran Vasegh Hamid Reza Momeni faculty of electrical and Computer engineering Tarbiat Modares University faculty of electrical and Computer engineering Shahid Rajaee Teacher Tehran Iran

The stability and stabilization of a class of nonlinear discrete time delayed systems(NDTDS) with time-varying delay and norm-bounded nonlinearity are investigated. Based on discrete time Lyapunov–Krasovskii functional method, a sufficient delaydependent condition for asymptotic stability of nonlinear systems is offered. Then, this condition is used to design a new efficient delayed state feedback controller(DSFC) for stabilization of such systems. These conditions are in the linear matrix inequality(LMI) framework. Illustrative examples confirm the improvement of the proposed approach over the similar cases. Furthermore, the obtained stability and stabilization conditions will be extended to uncertain discrete time delayed systems(UDTDS) with polytopic parameter uncertainties and also with norm-bounded parameter uncertainties.

关键词： nonlinear discrete time delayed systems Lyapunov–Krasovskii functional delayed state feedback linear matrix inequality(LMI) polytopic parameter uncertainties norm bounded parameter uncertainties

A Hybrid Coordinated Design Method for Power System Stabilizer and FACTS Device Based on Synchrosqueezed Wavelet Transform and Stochastic Subspace Identification

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Journal of Modern Power Systems and Clean Energy 2021年第4期9卷 910-918页

作者： Ayda Faraji Ali Hesami Naghshbandy Arman Ghaderi Baayeh Department of electrical engineering Faculty of EngineeringUniversity of KurdistanSanandajKurdistanIran

The occurrence of low-frequency electromechanical oscillations is a major problem in the effective operation of power systems. The scrutiny of these oscillations provides substantial information about power system stability and security. In this paper, a new method is introduced based on a combination of synchrosqueezed wavelet transform and the stochastic subspace identification (SSI) algorithm to investigate the low-frequency electromechanical oscillations of large-scale power systems. Then, the estimated modes of the power system are used for the design of the power system stabilizer and the flexible alternating current transmission system (FACTS) device. In this optimization problem, the control parameters are set using a hybrid approach composed of the Prony and residual methods and the modified fruit fly optimization algorithm. The proposed mode estimation method and the controller design are simulated in MATLAB using two test case systems, namely IEEE 2-area 4-generator and New England-New York 68-bus 16-generator systems. The simulation results demonstrate the high performance of the proposed method in estimation of local and inter-area modes, and indicate the improvements in oscillation damping and power system stability.

关键词： Low‐frequency oscillation modified fruit fly optimization algorithm Prony analysis stochastic subspace identification(SSI)algorithm synchrosqueezed wavelet transform(SSWT)

Investigation of Single-Wall MoS_2 Monolayer Flakes Grown by Chemical Vapor Deposition

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Nano-Micro Letters 2016年第1期8卷 70-79页

作者： Nihan Kosku Perkgoz Mehmet Bay Department of electrical and Electronics engineering Faculty of Engineering Anadolu University

Recently, two-dimensional monolayer molybdenum disulfide(MoS_2), a transition metal dichalcogenide, has received considerable attention due to its direct bandgap, which does not exist in its bulk form, enabling applications in optoelectronics and also thanks to its enhanced catalytic activity which allows it to be used for energy harvesting. However,growth of controllable and high-quality monolayers is still a matter of research and the parameters determining growth mechanism are not completely clear. In this work, chemical vapor deposition is utilized to grow monolayer MoS_2 flakes while deposition duration and temperature effect have been systematically varied to develop a better understanding of the MoS_2 film formation and the influence of these parameters on the quality of the monolayer flakes. Different from previous studies, SEM results show that single-layer MoS_2 flakes do not necessarily grow flat on the surface, but rather they can stay erect and inclined at different angles on the surface, indicating possible gas-phase reactions allowing for monolayer film formation. We have also revealed that process duration influences the amount of MoO_3/MoO_2 within the film network. The homogeneity and the number of layers depend on the change in the desorption–adsorption of radicals together with sulfurization rates, and, inasmuch, a careful optimization of parameters is crucial. Therefore, distinct from the general trend of MoS_2 monolayer formation, our films are rough and heterogeneous with monolayer MoS_2 nanowalls. Despite this roughness and the heterogeneity, we observe a strong photoluminescence located around 675 nm.

关键词： Monolayer Chemical vapor deposition Two-dimensional materials Molybdenum disulfide(MoS2)

Stochastic optimization for retailers with distributed wind generation considering demand response

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Journal of Modern Power Systems and Clean Energy 2018年第4期6卷 733-748页

作者： Hessam GOLMOHAMADI Reza KEYPOUR faculty of electrical and Computer engineering Semnan University

In this paper, a multi-stage stochastic model is presented for a renewable distributed generation(RDG)-owning retailer to determine the trading strategies existing in a competitive electricity market. Uncertainties associated with wholesale electricity market price, clients' consumption and power output of wind resources are considered through auto regressive integrated moving average(ARIMA) approach. In the proposed method, three trading floors are addressed for the retailer to hedge against the uncertainties. In the first stage, the retailer participates in day-ahead market to supply the clients and in the second stage, intraday market is addressed to allow the retailer to modify the schedule of its clients' consumption/RDG production. Due to unfavorable uncertainties, especially in renewable power production, real-time market is considered in the third stage to diminish the uncertainty at power delivery time. Cost function of wind resources considering capital, operation and maintenance(O&M) cost is incorporated in the objective function to increase the applicability of the mechanism. The proposed approach is formulated for risk-averse and risk-taker retailer through conditional value at risk(CVaR) approach. In order to study the impact of retail strategies on consumption patternand consumers' electricity bills, time-of-use(TOU)demand response programs are discussed in this *** the problem, the mixed integer non-linear programming(MILNP) problem is transformed into mixed integer linear programming(MILP) by jointly using decomposition and disjunctive constraints. Finally, a case study containing wind power resources, energy storage system and retailer is considered to analyze the proficiency of the proposed approach.

关键词： Renewable Retailer Stochastic Uncertainty Demand response