State simulation of water distribution networks based on DFP algorithm

The improved weighted-least-square model was used for state simulation of water distribution networks. And DFP algorithm was applied to get the model solution. In order to fit DFP algorithm,the initial model was transformed into a non-constrained optimization problem using mass conservation. Then,through one dimensional optimization and scale matrix establishment,the feasible direction of iteration was obtained,and the values of state variables could be calculated. After several iterations,the optimal estimates of state variables were worked out and state simulation of water distribution networks was achieved as a result. A program of DFP algorithm is developed with Delphi 7 for verification. By running on a designed network,which is composed of 55 nodes,94 pipes and 40 loops,it is proved that DFP algorithm can quickly get the convergence. After 36 iterations,the root mean square of all nodal head errors is reduced by 90.84% from 5.57 to 0.51 m,and the maximum error is only 1.30 m. Compared to Marquardt algorithm,the procedure of DFP algorithm is more stable,and the initial values have less influences on calculation accuracy. Therefore,DFP algorithm can be used for real-time simulation of water distribution networks.

Hot spot temperature prediction and operating parameter estimation of racks in data center using machine learning algorithms based on simulation data

In this paper,models to predict hot spot temperature and to estimate cooling air’s working parameters of racks in data centers were established using machine learning algorithms based on simulation data.First,simulation models of typical racks were established in computational fluid dynamics(CFD).The model was validated with field test results and results in literature,error of which was less than 3%.Then,the CFD model was used to simulate thermal environments of a typical rack considering different factors,such as servers’power,which is from 3.3 kW to 20.1 kW,cooling air’s inlet velocity,which is from 1.0 m/s to 3.0 m/s,and cooling air’s inlet temperature,which is from 16℃ to 26℃ The highest temperature in the rack,also called hot spot temperature,was selected for each case.Next,a prediction model of hot spot temperature was built using machine learning algorithms,with servers’power,cooling air’s inlet velocity and cooling air’s inlet temperature as inputs,and the hot spot temperatures as outputs.Finally,based on the prediction model,an operating parameters estimation model was established to recommend cooling air’s inlet temperatures and velocities,which can not only keep the hot spot temperature at the safety value,but are also energy saving.

一种基于DFT的低复杂度虚子载波OFDM信道估计算法

该文针对采用虚子载波的OFDM通信系统,提出了一种基于DFT的低复杂度信道估计算法,并与最小二乘(Least Square,LS)估计算法和线性最小均方误差(Linear Minimum Mean Square Error,LMMSE)算法进行了详细的性能和复杂度比较。所提DFT算法较好地降低了高斯白噪声的影响,相对于LS算法获得了较大的性能增益。该算法在复杂度与性能之间取得了较好的折衷,具有很好的实用价值。

一种基于DFT的高精度载波频偏估计算法

针对无线数字通信中的载波频率同步问题,提出一种新的载波频偏估计算法。利用离散傅里叶变换(DFT)内插技术,在较大频偏范围内估计出载波频偏,并且在估计精度上相对于DFT法有了很大的提高。这种算法不需要增加DFT数据长度,适合突发通信方式。进行了MonteCarlo仿真实验,仿真结果表明新算法不仅具有宽的估计范围,还具有高的估计精度。

基于DFT的2FSK信号解调自适应门限同步检测算法

传统的基于离散傅立叶变换(DFT)的频移键控(FSK)信号解调在同步检测中采用了固定门限,无法适应时变信道环境中信号衰减和噪声干扰的动态变化,实际应用中效果不佳。为了解决这个问题,首先在分析传统方法固有缺陷的基础上,提出了自适应门限同步检测的思路,然后应用随机信号检测与估计相关理论对检测算法进行了详细推导,并给出了自适应门限的计算公式,最后对算法的有效性及性能进行了仿真与分析,结果表明该方法所得的同步检测门限在不同信噪比情况下均能适应信道环境的动态变化,其虚警概率和检测概率的性能与理论相符,有效解决了时变信道环境下门限选择的问题。

一种新的DFT频偏估计算法

针对无线数字通信中的载波频率同步问题,提出一种新的载波频偏估计算法。利用离散傅立叶变换(DFT)算法,通过迭代算法,在较大频偏范围内估计出载波频偏,并且在估计精度上相对于DFT法有了很大的提高。这种算法不需要增加DFT数据长度,适合突发工作方式。Monte Carlo仿真实验的结果表明新算法不仅具有宽的估计范围,还具有高的估计精度。

GA-BASED MAXIMUM POWER DISSIPATION ESTIMATION OF VLSI SEQUENTIAL CIRCUITS OF ARBITRARY DELAY MODELS

In this paper, the glitching activity and process variations in the maximum power dissipation estimation of CMOS circuits are introduced. Given a circuit and the gate library, a new Genetic Algorithm (GA)-based technique is developed to determine the maximum power dissipation from a statistical point of view. The simulation on 1SCAS-89 benchmarks shows that the ratio of the maximum power dissipation with glitching activity over the maximum power under zero-delay model ranges from 1.18 to 4.02. Compared with the traditional Monte Carlo-based technique, the new approach presented in this paper is more effective.

改进的DFT正弦信号频率估计

通过分析Candan算法和2N点DFT算法的性能,本文提出了一种改进的基于DFT的正弦信号频率估计算法。在对原始信号进行必要的离散化预处理后,在粗估计阶段利用Candan算法估计出频率偏差,利用该频偏对原始信号进行频率修正。然后对修正后的原始信号进行2N点DFT算法精估计。由于增加了对原始信号的频率修正步骤,该算法发挥了Candan算法和2N点DFT算法的优点,同时增加了算法的复杂度。仿真结果表明,在相对频偏为任意值时,改进算法频率估计的均方根误差均接近克拉美罗下限,并且估计性能优于现有的频率估计算法。

TD-LTE-A信道估计DFT算法研究

TD-LTE-A信道估计的经典算法有最小平方(LS)算法,线性最小均方误差(LMMSE)算法以及基于变换域的离散傅里叶变换(DFT)算法。LS算法不需要知道信道的先验信息,但是对噪声没有做任何处理。LMMSE算法利用了信道的自相关矩阵,估计性能比LS要优良,但是计算较为复杂,不利于在实际系统中实现。DFT算法则是在LS算法估计结果的基础上,进行变换域处理。但是DFT算法存在较为明显的"地板效应"。然而,提出通过改进TDLTE-A系统的参数配置,可以有效地改善DFT算法的估计性能,使其性能接近于理想信道估计,并且通过仿真比较了DFT估计与其他信道估计算法在信道响应值的均方误差和信道冲击响应值的差异。

Estimation of Mutual Coupling Coefficient of the Array by Simulated Annealing Algorithm

We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing （SA） algorithm. The computer simulation has been conducted to illustrate the＇ excellent performance of this method and to demonstrate that it is statistically efficient. The benefit of this new method is that calibration signals and unknown signals can be received simultaneously, during the course of calibration.

Age estimation from facial images based on Gabor feature fusion and the CIASO-SA algorithm

Aiming at the problem of long time-consuming and low accuracy of existing age estimation approaches,a new age estimation method using Gabor feature fusion,and an improved atomic search algorithm for feature selection is proposed.Firstly,texture features of five scales and eight directions in the face region are extracted by Gabor wavelet transform.The statistical histogram is introduced to encode and fuse the directional index with the largest feature value on Gabor scales.Secondly,a new hybrid feature selection algorithm chaotic improved atom search optimisation with simulated annealing(CIASO-SA)is presented,which is based on an improved atomic search algorithm and the simulated annealing algorithm.Besides,the CIASO-SA algorithm introduces a chaos mechanism during atomic initialisation,significantly improving the convergence speed and accuracy of the algorithm.Finally,a support vector machine(SVM)is used to get classification results of the age group.To verify the performance of the proposed algorithm,face images with three resolutions in the Adience dataset are tested.Using the Gabor real part fusion feature at 48�48 resolution,the average accuracy and 1-off accuracy of age classification exhibit a maximum of 60.4%and 85.9%,respectively.Obtained results prove the superiority of the proposed algorithm over the state-of-the-art methods,which is of great referential value for application to the mobile terminals.

Algorithms of Confidence Intervals of WG Distribution Based on Progressive Type-II Censoring Samples

The purpose of this article offers different algorithms of Weibull Geometric (WG) distribution estimation depending on the progressive Type II censoring samples plan, spatially the joint confidence intervals for the parameters. The approximate joint confidence intervals for the parameters, the approximate confidence regions and percentile bootstrap intervals of confidence are discussed, and several Markov chain Monte Carlo (MCMC) techniques are also presented. The parts of mean square error (MSEs) and credible intervals lengths, the estimators of Bayes depend on non-informative implement more effective than the maximum likelihood estimates (MLEs) and bootstrap. Comparing the models, the MSEs, average confidence interval lengths of the MLEs, and Bayes estimators for parameters are less significant for censored models.

滑窗迭代DFT算法在电力谐波检测中的仿真研究

有源电力滤波器要求动态补偿准确、实时检出电网中瞬变的畸变电流。针对现有检测方法的不足,提出一种基于离散傅里叶变换的滑窗迭代DFT算法,实时测出谐波参考指令电流。该算法计算量小、容易工程实现,经过扩展,该算法还能应用于检测特定谐波。仿真实验结果验证了该算法的有效性和可行性。

基于DFT扩展广义多载波系统的信道估计方法研究

基于DFT扩展广义多载波系统,根据导频序列和导频时、频结构,针对上行链路系统,研究低复杂度的、易于实现的时域最大似然信道估计算法,并对算法进行了仿真,给出了仿真结论。

一种基于DFT的信道估计改进算法

论文在不同信道环境和不同子载波数下用Matlab对梳状导频插入的LS(最小平方)算法和基于DFT变换的信道估计算法进行了仿真。在总结两种算法估计的基础上,提出基于DFT的信道估计改进算法,并仿真分析该改进算法较传统算法在减小误码率和均方误差上的优越性。

混合超启发式算法求解复杂两级车辆路径问题

针对模糊需求下的绿色两级车辆路径问题,以最小化车辆运营成本和油耗成本之和为优化目标,提出一种混合超启发式算法进行求解.首先,考虑两级问题解空间庞大且相互耦合,设计一种聚类分解策略将该问题分解为多个子问题,以合理缩小问题搜索空间;然后,提出增强超启发式分布估计算法(enhanced hyperheuristic estimation of distribution algorithm,EHHEDA)对各个子问题进行求解,进而获得原问题的解.EHHEDA基于超启发式算法框架,在高层策略域设计一种基于三维概率模型的分布估计算法,动态确定由底层操作域中各搜索算子所组成的排列(即高层个体),可有效控制和引导整个算法的搜索行为;同时,在底层操作域设计10种有效邻域搜索算子,并加入重升温操作的模拟退火机制作为问题解(即底层个体)的接受准则,有利于在问题解空间中执行深入搜索.仿真实验结果表明,所提出的算法在大多数测试集上优于近年来用于求解类似问题的算法,验证了所提出算法的有效性.

应用插值FFT算法精确估计电网谐波参数

深入研究了插值快速傅里叶变换(FFT)算法在电网谐波参数估计中的应用.加窗宽度和窗函数的类型是影响插值FFT算法分析精度的主要因素.通过对常用窗函数的特性分析,得出了加窗宽度关于分析精度的估计公式.电网信号的基波幅值远大于各次谐波幅值,分析表明,Hanning窗比较适合分析电网信号,同时给出了基于Hanning窗的电网谐波幅值、频率和相位的显式计算公式.仿真结果证明,应用上述分析结果,电网谐波幅度、频率和相位的估计达到了预期的分析精度.

基于改进多中心-校正内点法的最优潮流

提出了一种改进的多中心-校正内点法,该方法采用超立体空间映射技术,通过合理配置一些关键映射参数改善映射空间的数值结构,使算法在每次迭代时能获得较大的迭代步长和较好的中心方向,从而加快算法的收敛。通过IEEE14、30、57、118节点4个测试系统的仿真计算表明,该算法收敛快,其迭代次数与每次迭代进行4次中心-校正计算的多中心-校正内点法基本相当,而且鲁棒性好,未出现数值稳定问题。文章还对算法收敛判据的设置和初值的选取作了较详细的讨论。

遗传算法在气动力参数辨识中的应用

将遗传算法推广用于气动力参数辨识,以取代通常采用的梯度类优化算法。通过采用遗传模拟退火算法对某型飞机的纵向气动力参数进行辨识计算及分析后,可以看到:(1)遗传算法是气动力参数辨识的一种新的有效方法,该算法不受参数初值选取的影响,具有较好的全局寻优特性;(2)遗传算法的计算效率受种群规模、遗传算法构造本身等因素的影响比较大,并且还有相当大的进一步完善与改进的空间。

正弦波信号频率估计快速高精度递推算法的研究

该文提出了一种正弦波频率估计的频偏校正算法,结合M-Rife算法精度高和频偏校正算法运算量小的特点,研究了一种快速高精度正弦波信号频率估计的递推算法。先对一个较短的截短信号序列用M-Rife算法进行频率初始估计,以此作初始值用频偏校正算法对一个更长的截短信号序列进行估计得到更精确的估计频率,并依此类推,在最后一步递推时,用M-Rife算法得到最终的估计频率。在信号序列较长时,该算法的运算量小于做一次FFT。仿真结果表明,该算法性能稳定,估计方差接近克拉美-罗限(Cramer-Rao Lower Bound,CRLB),与M-Rife算法相仿。该算法便于实时地实现高精度频率估计。