共查询到20条相似文献，搜索用时 250 毫秒
1.
Load voltage waveforms corresponding to symmetrical phase-angle triggering and integral-cycle triggering in single-phase thyristor circuits, and also the waveform due to half-wave rectification, are all discrete forms of amplitude modulation. In each case the modulated output voltage is obtained from a sinusoidal (supply) carrier signal by use of a rectangular modulating function, dependent on thyristor switching.The use of amplitude modulation (AM) techniques for frequency conversion in high power applications is subject to certain severe restrictions of performance. These restrictions can be largely overcome by the use of phase modulation (PM) methods which involve two channels of AM in each electrical supply line.Appropriate waveforms may be realised by the use of controlled switching of thyristors. These are arranged in combinations of inverse-parallel connected pairs forming subtractor modulators. Certain thyristor commutation problems arise in PM systems at high power levels. These problems can be overcome by producing so-called AM/PM waveforms that combine the separate advantages of AM and PM systems. 相似文献
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基于SystemView的16QAM调制与解调 总被引：1，自引：0，他引：1
正交振幅调制OAM(Ouadrature Amplitude Modulation)以其高频谱利用率、高功率密度等优势成为宽带无线接入和无线视频通信的重要调制方武.本文介绍16QAM调制解调的原理,然后给出原理框图并根据框图设计电路.最后提出了一种基于Systemview的16QAM实现方案. 相似文献
3.
研究了一种扩谱载波数字脉冲间隔调制SSC—DPIM(Spread spectrum carrier digital pulse interval modulation)技术并用于电力线载波扩谱通信系统．采用线性扫频SSC扩谱载波对DPIM符号进行编码，引入脉冲前导码作为传输数据块的同步信号以防止差错传播．介绍了数据传输速率及数据块传送差错率的理论分析结果．并采用单片机实现了SSC-DPIM电力线载波通信系统．实验结果表明，在同样的电力线网络环境下，其通信效果明显优于已有的电力线载波通信系统。 相似文献
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《Journal of The Franklin Institute》2021,358(16):8377-8395
The usage of communication networks provides a backbone of integration of information technologies and load frequency control (LFC) scheme. Time delays introduced by network environments taking the new challenge for dynamic performances and even the stability of closed-loop LFC scheme. This paper focuses on the stability and stabilization of multi-area LFC schemes for power systems with the introduction of communication networks and renewable energies. Markov theory is exploited in this paper for describing the discrete time-delay mechanism. Then, by utilizing Wirtinger-based inequality, and constructing a novel Lyapunov functions, the results of robust stability and stabilization criteria are derived in terms of linear matrix inequality (LMI). Finally, simulation results are provided to demonstrate the effectiveness and superiority of developed results. 相似文献
6.
隐马尔科夫模型在很多方面已有广泛应用.讨论了一类更为一般的模型,这类模型由Wojciech
Pieczynski首次提出,并且给出了在图像识别中的应用.这里首次给出在离散观测和离散状态下该模型的精确数学描述,其中包括建模、状态估计和参数估计,这些算法都是首次被提出的. 相似文献
7.
针对分时操作系统,依据任务执行时间提出系统性能损失作为性能参数,定义最佳节能条件并推出最佳节能频率的计算公式;进而重点论述为实现分时操作系统中的频率管理模块,在系统频率为离散值的前提下,如何对最佳节能频率进行有效近似;最后利用实现了频率管理模块的Linux,实验验证了最佳节能频率以及对其实现的正确性和有效性,而所增加的系统开销仅为3.63%. 相似文献
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This paper investigates the problem of sliding mode control (SMC) for discrete-time two-dimensional (2-D) systems subject to external disturbances. Given a 2-D Fornasini–Marchesini (FM) local state space model, attention is focused on designing the 2-D sliding surface and sliding mode controller, which guarantees the resultant closed-loop system to be asymptotically stable. Particularly, this problem is solved using the model transformation based method. First of all, sufficient conditions are formulated for the existence of a linear sliding surface guaranteeing the asymptotic stability of the equivalent sliding mode dynamics. Based on this, a sliding mode controller is synthesized to ensure that the associated 2-D FM system satisfies the reaching condition. The efficiency of the proposed 2-D SMC law design is shown by a numerical example. This paper extends the idea of model transformation to the 2-D systems and solves the SMC problem of a more general 2-D model in FM type for the first time. 相似文献
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采用基于消谐波技术通过直接数字合成正弦调制波(SPWM)和余弦调制波(CPWM)的正交双相信号,由单片机控制器控制波形存储器EPROM产生SPWM和CPWM,经过驱动电路控制逆变器,设计成正交双相逆变电源。电路结构简单,运行稳定可靠,输出电压波形无失真,可广泛应用于航空、航海、电力、铁路、邮电、医疗等诸多领域。 相似文献
10.
Delay-dependent guaranteed cost control for uncertain 2-D discrete systems with state delay in the FM second model 总被引：1，自引：0，他引：1
This paper is concerned with the problem of delay-dependent guaranteed cost control for uncertain two-dimensional (2-D) state delay systems described by the Fornasini and Marchesini (FM) second state-space model. Given a scalar α∈(0,1), a sufficient condition for the existence of delay-dependent guaranteed cost controllers is given in terms of a linear matrix inequality (LMI) based on a summation inequality for 2-D discrete systems. A convex optimization problem is proposed to design a state feedback controller stabilizing the 2-D state delay system as well as achieving the least guaranteed cost for the resulting closed-loop system. Finally, the simulation example of thermal processes is given to illustrate the effectiveness of the proposed result. 相似文献
11.
短波是目前常用的远距离通信手段,发射功率、工作频率、调制度、调制失真、谐波抑制是短波电台的重要工作指标。针对某型短波电台对外接口少、检测指标多的要求,设计一套基于计算机GPIB总线通信的测试系统,通过实时采集射频、音频、调制等信号来分析指标参数,从而实现短波电台的指标的自动测试。 相似文献
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本文详细的介绍了中国移动多媒体广播的基本原理、主要特点、技术路线,重点解读和分析了CMMB的核心STIMI技术,通过对国标GY/T220.1《移动多媒体广播第1部分:广播信道帧结构、信道编码和调制》的系统解读和分析,对STIMI技术进行了深层次的分析,尤其在OFDM频域符号的形成以及调制方面更是通过MATLAB进行了仿真,仿真结果符合国标。最后在文章的末尾将空时编码引入,提出了针对CMMB的改进方案。 相似文献
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Theodore S. Koubanitsas 《Journal of The Franklin Institute》1976,301(5):399-408
Previous studies of Delta Modulation (DM) were predominantly concerned with various aspects of noise introduced by the quantising process. This paper is primarily directed towards the DM-signal behaviour, a concern which becomes necessary when optimizing the DM-system against the disturbances of the transmission channel. The statistics of the output signal is considered analytically under the assumption of independent input-signal samples. The approximate distribution of the output signal is derived and graphically compared with the exact distribution. Finally, the incidence of sample correlation is considered on the basis of results produced by means of simulation. 相似文献
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Sreten B. Stojanovic Dragutin Lj. Debeljkovic Dragan S. Antic 《Journal of The Franklin Institute》2014
In this paper, the problem of finite-time stability analysis for linear discrete time-delay systems is studied. By using the classical Lyapunov-like functional and Lyapunov-like functionals with power or exponential functions, some sufficient conditions for finite-time stability of such systems are proposed in the form of the linear matrix inequalities. The six aggregate norm approximations of the delayed states are introduced to establish the relations between the classical Lyapunov-like functional and its difference. To further reduce the conservatism of stability criteria, three inequalities with delayed states for the estimation of Lyapunov-like functional are proposed. A numerical example is included to illustrate the effectiveness and advantage of the proposed methods. 相似文献
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介绍了利用TI的DSP电机控制芯片TMS320F2812实现SVPWM的方法。该控制方法速度快、精度高,在电压型逆变器中能产生更少的谐波并减少开关损耗。 相似文献
16.
电力来源清洁化对于中国的环境保护和能源安全有重要意义。了解公众对电力来源清洁化的偏好及支付意愿可为政府制定能源改革政策提供支撑。本文采用离散选择实验法研究了公众对电力来源清洁化的偏好和支付意愿,分析了电力来源结构、环境影响（CO2、SO2排放量）、电价等属性对偏好的影响以及不同特征个体间偏好的差异。基于在中国10个主要城市收集到的1008份有效问卷,本文运用Mixed Logit模型和Latent Class模型分析了数据。结果发现：①公众对电力来源的偏好存在地域差异;②电力来源带来的环境影响以及电价的增加均与公众对电力清洁化偏好程度呈负相关;③不同特征的个体对电力来源的偏好也不同,年龄越大、收入越高、居住地越靠近城市和越重视环保的受访者,越偏好清洁的电力来源;④公众愿意为SO2或CO2排放量降低30%的清洁电力多支付31%的电价,公众的环保态度对该支付意愿的影响（差异为26%左右）大于社会经济特征（如年龄）对支付意愿的影响（差异为15%左右）。基于此,本文建议在各地采用精细化的政策促进电力来源清洁化,以及增强公众的环保意识,尤其是低收入群体、年轻群体和乡村群体,从而提高公众对清洁可再生能源的接受度和支付意愿。 相似文献
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《Journal of The Franklin Institute》2023,360(10):6693-6711
In this paper, we consider the discrete memory-less three-way degraded broadcast channel (3WDBC). The main contribution of this paper is in characterizing the capacity region of the discrete memoryless 3WDBC. To end up with this goal, we first develop the achievable region. Then, an outer bound to the capacity region is also derived. Next, the achievable region is shown to meet the outer bound such that the capacity is achieved. After that, the 3WDBC is shown to encompass many well-known multi-user networks such as (i) broadcast channel, (ii) multiple access channel, (iii) two-way channel, and (iv) relay channel. Further, the achievable capacity region is then extended to the additive Gaussian noise channel. Specifically, superposition encoding is employed at each user such that a given user can appropriately allocate its power to broadcast to the other two users. In this direction, two design criteria are theoretically presented and numerically investigated to show the range that the power allocation factor at each user may have. 相似文献
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介绍了空间矢量脉宽调制(SVPWM)的基本原理,提出了在Matlab/Simulink环境下用S函数实现空间矢量脉宽调制模块的方法,描述了仿真模型的设计过程和编程要点,并将其应用到有源电力滤波器的仿真系统中。给出了仿真结果,为基于SVPWM的有源电力滤波器的研究打下了基础。 相似文献
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Donald L. Margolis 《Journal of The Franklin Institute》1983,316(3):261-271
Semi-active systems are those in which a passive, dissipative element (damper, friction clutch, fluid orifice) is modulated, via low power inputs, to enhance the performance of its associated dynamic system. This type of control is inherently nonlinear, thus forcing the closed-loop response of the total system to be determined numerically using a digital computer. Although, strictly speaking, the frequency response for nonlinear systems does not exist, it is typical to simulate semi-active systems with sinusoidal input and present results as frequency transmissibilities. This paper uses energy dissipation per cycle to determine an approximate frequency response of semi-active systems requiring only a calculator for numerical analysis. 相似文献
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In parallel hybrid electric vehicles (HEVs), the power split between the engine and the electric motor as well as the gear shift in the gearbox determines the overall energy efficiency. In this paper an adaptive energy management strategy with velocity forecast is proposed to optimize the fuel consumption in parallel HEVs, which is formulated into a mixed-integer optimization problem. Approximate dynamic programming with a novel actor-gear-critic design is presented for simultaneously controlling the power split and gear shift online. The power split as a continuous variable is determined from an actor network to realize the energy distribution between two power sources. The gear shift as a discrete variable is obtained from a gear network to adjust the gear ratio in the gearbox. The concept enables an online learning of the energy management strategy for different driving behaviors without the requirement of a system model and the driving cycle. Simulation results indicate that the proposed strategy achieves close fuel economy compared with the optimal solutions resulting from dynamic programming. Furthermore, a multi-stage neural network is introduced for velocity forecast, providing a computationally efficient training framework with good prediction performance. The velocity prediction is finally combined with the energy management strategy for an effective application and fuel economy. 相似文献