共查询到20条相似文献，搜索用时 31 毫秒
1.
A fuzzy adaptive tracking control scheme is proposed for MIMO nonlinear time-varying delay systems. A fuzzy T-S model-based adaptive time-varying delay fuzzy logic systems is developed to approximate the unknown nonlinear time-varying delay functions.Thus, the modeling to nonlinear systems is implemented. The update laws for parameters of the fuzzy logic systems are derived by the tracking error. A Hcompensator is designed to eliminate fuzzy approximation errors and external disturbances. Based on Lyapunov stability theorem, the proposed control scheme can guarantee the stability of the closed loop systems and obtain anticipant Htracking performance as well. Simulation results of the manipulator demonstrate the effectiveness of the control scheme. 相似文献
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自适应加权最小二乘支持向量机的空调负荷预测 总被引：1，自引：0，他引：1
为了提高建筑空调负荷的预测精度,在分析空调负荷主要影响因素的基础上提出了一种基于自适应加权最小二乘支持向量机(AWLS-SVM)的建筑空调负荷预测方法。该方法根据预测误差的统计特性,采用基于改进正态分布加权规则,自适应地赋予每个建模样本不同的权值,以克服异常样本点对模型性能的影响。建模过程中采用粒子群优化(PSO)算法对模型参数进行优化,以进一步提高模型预测精度。基于DeST模拟数据将AWLS-SVM方法应用于南方地区某办公建筑的逐时空调负荷预测中,并与径向基神经网络(RBFNN)模型、LS-SVM模型及WLS-SVM模型作比较,其平均预测绝对误差分别降低了51.84 %、13.95 %和3.24 %,并进一步基于实际空调负荷数据将该方法应用于另一办公建筑的逐日空调负荷预测中。预测结果表明：AWLS-SVM预测的累积负荷误差为4.56 MW,亦优于其他3类模型,证明了AWLS-SVM具有较高的预测精度和较好的泛化能力,是建筑空调负荷预测的一种有效方法。 相似文献
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An item-document weight matrix representing the web pages could be generated by constructing the vector space model. Since the efficiency of direct classification through the high-dimensional matrix is relatively low, a fuzzy webpage text classification algorithm combined with improved nonnegative matrix factorization (NMF) is presented. Firstly, the original high-dimensional data are mapped into the low-dimensional semantic space via an iterative normalized compression NMF(NCMF) to reduce the complexity of the problem. Secondly, in order to solve the problem of categorizing ambiguous words by using deterministic matrices, fuzzy logic is incorporated into the classification model, where the fuzzy categorization set of the document is constructed with the fuzzy membership degree between features and categories. Comparative experiment results demonstrate the proposed classification algorithm possesses higher accuracy and better time performance. 相似文献
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应用灰板校正提高计算机视觉预测棉花植株含水量的精确度 总被引：1，自引：0，他引：1
利用灰板校正以消除棉花不同生育期图片颜色特征值的亮度差异,建立适用于不同生育期预测植株含水量的通用模型,以提高运用计算机视觉技术进行棉花植株含水量预测的精度。研究结果表明,由灰板校正前、后颜色特征值G-B建立的最佳预测模型,决定系数分别为0.746和0.782。有效性检验结果表明,灰板校正前、后计算预测值与实测值的决定系数分别为0.739和0.783;RMSE分别为2.218和2.03,RE分别为2.13%和1.79%。基于计算机视觉提取的冠层图片颜色特征值能够预测植株含水量,应用灰板校正颜色特征值能够提高模型预测精度,可为提高计算机视觉预测植株水分状况的精度提供技术支撑和方法补充。 相似文献
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In order to consider the feasibility of practical implementation and reduce the complexity of OFDM systems, an improved SLM algorithm is proposed. The original data are segmented and scrambled, which breaks the correlation of the original data sequences, and reduces all sub-carrier phase coherence, thereby reducing the OFDM system PAPR. Following the linear nature of the Fourier transform, the obtained IFFT data sequences are linearly combined to get the new scrambling code sequences, such that strictly controlling the IFFT number, while getting more data sequences, which further reduces the system PAPR, and significantly reduces the computational complexity of the system. Theoretical analysis and simulation results show that the improved SLM algorithm can effectively suppress PAPR, while reducing the algorithm complexity and system complexity. 相似文献
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在总结分析了几种常用综合评价方法的基础上, 提出了一种反映观察值与理论值之间相似性的新算法--符合度。该算法就评价信息个体(观察值)与标准值(期望值)的马氏距离, 再由马氏距离转化为评价对象与标准的接近程度, 即符合度(r)。首先进行指标数(p)、相似度(r)与马氏距离(d)的模拟试验, 再通过曲面拟合的方法找出它们之间的关系模型。通过大量抽样试验, 验证符合度的次数分布与原先设定的符合度的良好对应关系, 说明模型的可行性与可靠性。以小麦RVA性状为指标, 利用该算法分析扬麦系统若干品种之间的接近程度, 并评价多变数复杂效应回归分析模拟试验的结果。符合度算法不需要数据标准化处理, 直接利用原始数据, 减少了计算工作量, 降低了因数据标准化处理方法不同而引起的评价结果差异, 同时由于不需要赋权, 排除了主观性的影响, 保证了信息的完整性以及评价结果的可靠性。
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A new data culling and labeling method is proposed to avoid misleading outcomes caused by multi-state samples during drift compensation process. This method culls data by the curve slops of gas sensor array response and labels data by comparing input samples with the memories of pattern recognition algorithm to avoid occurrence of misleading results. Experiments show the method combined with on-line drift compensation algorithm can estimate sample-states automatically and increase the recognizing accuracy from 37.5% to 100%. 相似文献
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A robust method to compensation illumination of driver video color image to enhance image quality has been proposed. Firstly, the original image is decomposed into high-frequency image and low-frequency image based on spatial image decomposition. The illumination information is completely contained in the low-frequency image. Next, low-frequency image is compensated by using Retinex approach which can brighten the darker area. Then, the compensated low-frequency image and high-frequency image are synthesized. Finally, new image is obtained by illumination balance of synthesized image. Results show that the algorithm has better results compared with the traditional algorithm. 相似文献
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Fuzzy controller can achieve satisfactory dynamic performance even for complicated process without mathematical model of the process.Its main imperfection is the existence of steady state error and ultimate oscillatory in the process output. This limits its application area. How to eliminate the steady state error while keep its good dynamic performance has been paid much attention. The strategy to introduce integral function to the conventional fuzzy control system is put forward in this paper to overcome the above problem. After expound two key factors on introducing integral action,an intelligent integral algorithm has been employed,and two methods on introduction of the intelligent integral to the fuzzy control system are proposed. Their characteristics and applied situations are summarized. 相似文献
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为分析棉花叶片全氮含量（LNC）与冠层光谱反射特征的关系,实现作物生长过程中氮素水平的快速、准确和无损监测,以石河子大学教学试验场2019年棉花小区试验为基础,选用多元散射校正、SG平滑算法、变量标准化校正和一阶导数4种方法分别对棉花冠层原始光谱进行预处理,使用随机蛙跳（random frog,RF）和连续投影算法（successive projections algorithm,SPA）筛选特征波长并结合偏最小二乘回归法建立棉花LNC光谱估算模型。RF和SPA算法从棉花冠层398～1000nm的光谱中优选5组LNC的敏感特征波段,波段数目下降了93.0%～96.3%,有效降低了光谱的冗余信息;基于SPA算法筛选的敏感波段构建的LNC偏最小二乘回归模型的决定系数和均方根误差分别为0.52和2.55,模型验证的决定系数和均方根误差分别为0.70和2.37,模型具有较好的精度和稳定性,可作为棉花LNC的无人机高光谱估算方法。 相似文献
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MDBPSO算法优化的全波段光谱数据协同冠层SIF监测小麦条锈病 总被引：1，自引：0，他引：1
为了从全波段光谱数据中提取对小麦条锈病敏感的特征参量,提高小麦条锈病遥感探测模型的运行效率和精度,本文首先从惯性权重和粒子更新方式两个方面对传统离散粒子群算法(discretebinaryparticleswarmoptimization, DBPSO)进行改进,利用改进离散粒子群算法(modified discrete binary particle swarm optimization, MDBPSO)从全波段光谱数据中优选遥感探测小麦条锈病严重度的特征变量,然后与冠层日光诱导叶绿素荧光(solar-inducedchlorophyllfluorescence,SIF)数据相结合作为自变量分别利用随机森林(randomforest,RF)和后向传播(backpropagation,BP)神经网络算法构建小麦条锈病遥感探测模型,并将其与相关系数(correlationcoefficient,CC)分析法和DBPSO算法提取特征参量构建模型的精度进行对比分析。结果表明:(1) MDBPSO算法比传统DBPSO算法具有更快的收敛速度和更高的寻优精度,改进前后其迭代次数从395次减少到156次,最优适应度函数(optimumfitnessvalue,OFV)值从0.145减小到0.127。(2)采用MDBPSO算法选择特征变量时,RF和BP神经网络两种方法构建的模型精度均高于CC分析法和DBPSO算法,其中RF算法预测病情指数(diseaseindex,DI)值和实测DI值间的检验集决定系数(validation set determination coefficient, R2V)比CC分析法和DBPSO算法分别提高了9%和3%,均方根误差(validation set root mean square error, RMSEV)分别降低了28%和11%, BP神经网络算法预测DI值和实测DI值间的R2V比CC分析法和DBPSO算法分别提高了13%和6%,RMSEV分别降低了21%和10%,利用MDBPSO算法优选特征参量能够提高小麦条锈病的遥感探测精度。(3)在MDBPSO、DBPSO和CC分析法3种特征选择算法中,RF算法构建的模型精度均高于BP神经网络算法,其中RF模型预测DI值和实测DI值间的R2V比BP神经网络算法至少提高了7%,平均提高了9%,RMSEV至少降低了15%,平均降低了20%。以MDBPSO算法优选的特征参量为自变量利用RF方法构建的小麦条锈病遥感探测的MDBPSO-RF模型是小麦条锈病遥感探测适宜模型,该研究结果为进一步实现作物健康状况大面积高精度遥感监测提供了新的思路。 相似文献
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利用机载激光雷达的林木识别与参数反演 总被引：3，自引：0，他引：3
为了提高利用机载激光雷达林木识别精度,以全波形激光雷达分解数据为基础,首先利用控制标记分水岭算法对树冠高程模型进行分割,初步确定单株木位置;然后结合单株木结构特征,在三维空间中利用马尔可夫随机场进行单株木点云分割;最后,使用9个样地实测数据对激光雷达反演的林木参数进行回归分析验证。结果表明：单株木识别率为76%,位置误差均值和方差分别为0.67、0.19 m,单株木树高、树冠直径和胸高径的RMSE分别为1.03 m（4.57%）、0.56 m（10.48%）、3.01 cm（11.01%）,样地断面积和材积的RMSE分别为2.42 m2/hm2（8.11%）和17.83 m3/hm2（9.11%）。本研究能有效提高单株木点云分割精度,能满足单株木和林分参数反演要求,提高林业调查的自动化程度。 相似文献
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The sampling speed for the ultra wide band (UWB) channel is too high to realize with the existing sampling technology. To solve the problem, a novel blind channel estimation algorithm was presented based on the theory of compressive sensing. Firstly, some measurements are obtained which are linear combinations of the received signals multiplied by a random incoherent measurement matrix. Then, the mathematical model is established by exploiting the first statistics of the measurements. Finally, the orthogonal matching pursuit (OMP) algorithm is utilized to get the estimating channel parameters. With the proposed algorithm, the number of the measurements need for channel estimation is much smaller than that of the samples needed for the existing algorithms, which reduces the ADC resources greatly. The simulation result shows that the estimation performance of the algorithm is good, while the bit error rate (BER) is only 2~3dB higher than that of the exact channel. 相似文献
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[Objective] The aim of this study was to improve the cotton image segmentation accuracy in a picking robot image processing system. [Method] An image segmentation algorithm based on a fusion method of Markov random field and quantum particle swarm optimization clustering was proposed. The process of the proposed algorithm is as follows: first, transform the RGB (red, green, blue) images into grayscale; second, use it to segment these images; finally, the threshold of the connected area is set on the basis of the segmented image to obtain the target area. Then, the cotton front image and the cotton side image are selected from the images collected from different angles. The segmentation experiment was carried out by using this algorithm, and compared with the Otsu algorithm, the fuzzy C-means algorithm, the quantum particle swarm image segmentation algorithm and the Markov random field image segmentation algorithm. [Result] The results showed that the segmentation accuracy and peak signal to noise ratio of the proposed algorithm were 98.94% and 77.48 dB. When compared with the Otsu algorithm, fuzzy C-means algorithm, quantum particle swarm optimization algorithm and Markov random field algorithm, the average segmentation accuracy and peak signal to noise ratio of the proposed algorithm increased by 2.47%–4.56%, and 9.81–13.11 dB, respectively. [Conclusion] The proposed algorithm had higher segmentation accuracy and higher peak signal to noise ratio than the other algorithms tested. 相似文献
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During the melting and processing practices, an accurate knowledge of liquidus temperature is necessary in the determination of process parameters relating to a given alloy. Adaptive neuro-fuzzy inference system (ANFIS) modeling method has been used to improve accuracy of prediction for liquidus temperature based on the compositions of Al-Si series cast alloys. The developed fuzzy inference system could extract Takagi-Sugeno type fuzzy rules from data directly, and has a feed-forward network structure with supervised learning capability. In order to adapt the parameters of the model, the proposed fuzzy inference system is trained over a wide range of compositions from the published data of industrial alloys. The result shows that, the developed ANFIS model can capture non-linear relationships between compositions and liquidus temperature, and then provides better prediction than the reported multiple statistic analysis. The developed model can be used to predict the liquidus temperature needed in computer modeling and thermodynamic calculation, which are needed in the aluminium alloys casting industry and research. 相似文献
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Orthogonal frequency division multiplexing (OFDM) is sensitive to the in-phase and quadrature-phase (IQ) imbalance induced by the direct conversion architectures. A compensation scheme of IQ imbalance exploiting null subcarriers in OFDM symbols is presented. The proposed algorithm is with high bandwidth utilization because the training symbols are not required. The effect of IQ imbalance on OFDM systems is studied, and the mirror relationship between the FFT of a sequence and that of its conjugate is employed to estimate and compensate the IQ imbalance. This method can be applied to multiple input multiple output (MIMO) OFDM systems with space time block code (STBC). Performance analysis shows that the proposed algorithm is asymptotically unbiased. The variance is inversely proportional to the number of OFDM symbols, null subcarriers, the SNR and the channel frequency response, and proportional to the IQ imbalance. Simulation results demonstrate that this scheme can obtain almost the optimal bit error rate (BER). 相似文献
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汽车转弯自动照明控制系统数据采集滤波方法 总被引：1，自引：0，他引：1
为了减少汽车转弯自动照明控制系统数据滤波处理中的延时,在滑动中值滤波方法基础上,提出了一种带补偿的限幅滑动中值滤波算法,通过补偿的方式跟随信号的变化趋势。该算法通过2个步骤完成滤波,先对数据进行带补偿方式的限幅处理,再进行滑动中值滤波处理。该算法综合了滑动中值滤波法的实时性以及限幅滤波法对偶然性干扰滤除的有效性,实现更准确的滤波。仿真与实测结果表明,与滑动中值滤波方法相比较,改进后的算法滤波能够实时地滤除数据中的干扰,处理时间可减少62%,滤波效果较好,且速度信号的数据滞后时间较短,实时性较高,满足系统设计要求。 相似文献