共查询到20条相似文献,搜索用时 140 毫秒
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在加性高斯白噪信道条件下,采用置信度传播算法对LDPC码进行译码,需要精确估计信道信噪比用于计算接收比特的后验概率消息作为译码器的输入.信噪比值的错误估计称为信噪比失配.本文研究加性高斯白噪信道条件下信噪比失配对LDPC码译码的影响.通过对置信度传播算法校验节点更新方程的近似得到一个以信噪比为自变量的校正因子函数,基于... 相似文献
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传统的无人机与地面接收机之间的信道编码采用Turbo码、LDPC码等.Turbo码和LDPC码译码复杂、实时性不足、硬件成本高,其中LDPC码在高信噪比时候易导致错误地板.格雷码运算复杂度低,运算时间少,硬件实现简单且功耗也相对更低.针对这一现状,本文提出了基于格雷码的无人机图像传输自适应译码算法.在格雷码软硬判决译码算法的基础上设计了依据奇偶校验位的译码判决机制.仿真结果表明,该算法复杂度低、运行速度快、可靠性好,硬件成本低,可在满足图像精度需求下自适应地选择合适的解码方法,提高解码速度. 相似文献
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基于三维特征参数的贝叶斯推理电路功耗模型 总被引:1,自引:0,他引:1
在功耗与信号统计分析的基础上,采用贝叶斯推理技术建立周期精确的功耗宏模型.通过分析信号特征对电路功耗的影响,选择输入信号密度Pin、输入跳变密度Din和输出跳变密度Dout作为贝叶斯推理的三维特征参数,证明了上述特征参数对信号时间和空间相关性信息的覆盖.实验结果表明,该方法较目前的门级功耗分析速度提高400余倍,周期功耗平均误差可以控制在10%以内. 相似文献
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EXIT(EXtrinsic Information Transfer)图分析方法可以看作密度进化技术的一种简化,具有实现简单的优点,并且在不同的信道、调制方案以及检测器中都可以使用。在详细阐述了EXIT图分析方法的基础上,给出了基于EXIT图的正则LDPC码的门限判决算法,进一步通过计算机仿真分别给出了变量节点译码器和校验节点译码器的EXIT曲线,以及不同的信道信噪比下(3,6)正则LDPC码EXIT图的变化规律,直观地对迭代译码过程中的互信息变化进行了描述分析。 相似文献
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杜比AC-3的IMDCT算法分析及定点仿真 总被引:1,自引:0,他引:1
杜比AC-3的硬件解码器设计中,使用定点运算单元比浮点运算单元成本低,但是定点数动态范围小,尤其是IMDCT 模块中需要大量乘加运算,多次迭代后误差会明显增大,因此需进行定点仿真来选择合适的字长以确保信噪比的要求.文中先对IMDCT算法进行分析,用推导来阐释IFFT实现IMDCT的方法.文中后半部分讲述对IMDCT进行定点仿真的方法,然后用Matlab的Simulink作为仿真平台,对不同字长的IMDCT模块进行仿真,并给出仿真结果.通过定点仿真不仅能得出不同规格的硬件Ac-3解码器所需的运算字长,而且仿真模型的运算结果和中间数据可以为硬件的测试向量来验证硬件解码器的正确性. 相似文献
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蒙特卡罗MC方法是核反应堆设计和分析中重要的粒子输运模拟方法.MC方法能够模拟复杂几何形状且计算结果精度高,缺点是需要耗费大量时间进行上亿规模粒子模拟.如何提高蒙特卡罗程序的性能成为大规模蒙特卡罗数值模拟的挑战.基于堆用蒙特卡罗分析程序RM C,先后开展了基于TCMalloc动态内存分配优化、OpenMP线程调度策略优... 相似文献
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混合储能可快速平滑微网中分布式电源出力的随机性,从而提升配电网可靠性。提出了一种基于网络划分的蒙特卡洛模拟法,定量研究了含混合储能微网对配电网可靠性的影响。首先建立蓄电池与超级电容组成的混合储能系统模型并制定其充放电策略;在设备发生故障后,根据系统区域划分和负荷削减模型,确定负荷停电原则,采用序贯蒙特卡洛模拟法计算可靠性指标。以改进的IEEE RBTS BUS6系统为算例,对比分析了不同储能方式的微网接入前后的系统可靠性指标,结果表明:含混合储能微网接入配电网,能提高配电网供电的可靠性。 相似文献
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Sudib K. Mishra Samit Ray Chaudhuri Subrata Chakraborty George Frantziskonis 《Engineering with Computers》2009,25(4):367-378
Monte Carlo simulation in conjunction with Fourier transform based spectral windowing is used to model the live load on bridges.
Vehicles are classified into a few groups and the probability distributions of axle weight and length associated with each
group are estimated. The vehicle arriving at an instant is determined through Monte Carlo simulation, which uses a vehicle
group density function derived from measurement data on the relative contribution of each group in total vehicles. The weight
and length of the arriving vehicle is also simulated by Monte Carlo using the distribution function for the corresponding
group. Vehicle arrivals are modeled by the Poisson distribution. The vehicle velocities are realized through spectral simulation
based on decaying power spectra of the velocity time series. The simulations are performed for a sufficient time interval
in several lanes, thus the ensemble sampling of load is obtained. Fourier transform based windowing is used to characterize
the power spectra of mechanical load on the bridge. The study shows the white noise nature of the load spectral density, which
is in agreement with the assumptions of previous investigators. Parametric sensitivity of the spectra is also performed and
recommendations are made to include site-specific parameters in the model. Finally, applications are illustrated for frequency
domain random vibration analysis of a simple model of bridge structures. 相似文献
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当马尔可夫系统规模较大时,需要采用蒙特卡罗方法计算其瞬态不可用度,如果系统的不可用度很小,则需要采用高效率的蒙特卡罗方法.本文在马尔可夫系统寿命过程的积分方程的基础上,给出了系统瞬态不可用度计算的蒙特卡罗方法的统一描述,由此设计了马尔可夫系统瞬态不可用度计算的直接统计估计方法和加权统计估计方法.用直接仿真方法、拟仿真方法、基于直接仿真的统计估计方法、基于拟方仿真的统计估计方法和加权统计估计方法计算了-可修Con/3/30:F系统的瞬态不可用度.结果表明,由于同时采用了偏倚的抽样空间和逐次事件估计量,加权统计估计方法的方差最小,当系统不可用度很小时,该方法效率最高. 相似文献
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In order to endow the expansion-based stochastic formulation with the capability of representing the characteristic behavior of stochastic systems, i.e., the non-linear dependence of the response variability on the coefficient of variation of the stochastic field, a Monte Carlo simulation-compatible stochastic field is suggested. Through a theoretical comparison of displacement vectors in the Monte Carlo method and an expansion-based scheme, it is found that the stochastic field adopted in the expansion-based scheme is not compatible with that appearing in the Monte Carlo simulation. The Monte Carlo simulation-compatible stochastic field is established by means of enforcing the compatibility between the stochastic fields in the expansion-based scheme and the Monte Carlo simulation. Employing the stochastic field suggested in this study, the response variability is reproduced with high precision even for uncertain fields with a moderately large coefficient of variation. Furthermore, the formulation proposed here can be used as an indirect Monte Carlo scheme by directly substituting the numerically simulated random fields into the covariance formula. This yields a pronounced reduction in the computation cost while resulting in virtually the same response variability as the Monte Carlo technique. 相似文献
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A program for predicting significant RNA secondary structures 总被引:7,自引:0,他引:7
We describe a program for the analysis of RNA secondary structure. There are two new features in this program. (i) To get vector speeds on a vector pipeline machine (such as Cray X-MP/24) we have vectorized the secondary structure dynamic algorithm. (ii) The statistical significance of a locally 'optimal' secondary structure is assessed by a Monte Carlo method. The results can be depicted graphically including profiles of the stability of local secondary structures and the distribution of the potentially significant secondary structures in the RNA molecules. Interesting regions where both the potentially significant secondary structures and 'open' structures (single-stranded coils) occur can be identified by the plots mentioned above. Furthermore, the speed of the vectorized code allows repeated Monte Carlo simulations with different overlapping window sizes. Thus, the optimal size of the significant secondary structure occurring in the interesting region can be assessed by repeating the Monte Carlo simulation. The power of the program is demonstrated in the analysis of local secondary structures of human T-cell lymphotrophic virus type III (HIV). 相似文献
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Cristiano Castelfranchi Rino Falcone Babak Sadighi Firozabadi Yao-Hua Tan 《Applied Artificial Intelligence》2013,27(8):763-768
This paper applies network flow method, genetic algorithms, and Monte Carlo simulation to optimal reliability design for a composite electric power system. Genetic algorithms are general purpose optimization techniques based on principles inspired from the biological evolution using three main operations of reproduction, crossover, and mutation, which could locate near optimal solutions in most cases. The proposed method primarily adopted Monte Carlo simulation method, maximum-flow minimum-cut theorem, and optimization techniques to find out the optimal values of reliability indices, such that the optimal reliability design for the system can be achieved. The objective function to be optimized is composed of interruption cost and installation cost. The reliability indices mainly used include expected demand not served (EDNS) and forced outage rate (FOR). An application of the proposed method conducted on an IEEE five-bus test system is presented. 相似文献