Borehole-GPR numerical simulation of full wave field based on convolutional perfect matched layer boundary

The absorbing boundary is the key in numerical simulation of borehole radar.Perfect match layer(PML) was chosen as the absorbing boundary in numerical simulation of GPR.But CPML(convolutional perfect match layer) approach that we have chosen has the advantage of being media independent.Beginning with the Maxwell equations in a two-dimensional structure,numerical formulas of finite-difference time-domain(FDTD) method with CPML boundary condition for transverse electric(TE) or transverse magnetic(TM) wave are presented in details.Also,there are three models for borehole-GPR simulation.By analyzing the simulation results,the features of targets in GPR are obtained,which can provide a better interpretation of real radar data.The results show that CPML is well suited for the simulation of borehole-GPR.

Uniform stable conformal convolutional perfectly matched layer for enlarged cell technique conformal finite-difference time-domain method

Based on conformal construction of physical model in a three-dimensional Cartesian grid,an integral-based conformal convolutional perfectly matched layer（CPML） is given for solving the truncation problem of the open port when the enlarged cell technique conformal finite-difference time-domain（ECT-CFDTD） method is used to simulate the wave propagation inside a perfect electric conductor（PEC） waveguide.The algorithm has the same numerical stability as the ECT-CFDTD method.For the long-time propagation problems of an evanescent wave in a waveguide,several numerical simulations are performed to analyze the reflection error by sweeping the constitutive parameters of the integral-based conformal CPML.Our numerical results show that the integral-based conformal CPML can be used to efficiently truncate the open port of the waveguide.

A multi-source information fusion layer counting method for penetration fuze based on TCN-LSTM

When employing penetration ammunition to strike multi-story buildings,the detection methods using acceleration sensors suffer from signal aliasing,while magnetic detection methods are susceptible to interference from ferromagnetic materials,thereby posing challenges in accurately determining the number of layers.To address this issue,this research proposes a layer counting method for penetration fuze that incorporates multi-source information fusion,utilizing both the temporal convolutional network(TCN)and the long short-term memory(LSTM)recurrent network.By leveraging the strengths of these two network structures,the method extracts temporal and high-dimensional features from the multi-source physical field during the penetration process,establishing a relationship between the multi-source physical field and the distance between the fuze and the target plate.A simulation model is developed to simulate the overload and magnetic field of a projectile penetrating multiple layers of target plates,capturing the multi-source physical field signals and their patterns during the penetration process.The analysis reveals that the proposed multi-source fusion layer counting method reduces errors by 60% and 50% compared to single overload layer counting and single magnetic anomaly signal layer counting,respectively.The model's predictive performance is evaluated under various operating conditions,including different ratios of added noise to random sample positions,penetration speeds,and spacing between target plates.The maximum errors in fuze penetration time predicted by the three modes are 0.08 ms,0.12 ms,and 0.16 ms,respectively,confirming the robustness of the proposed model.Moreover,the model's predictions indicate that the fitting degree for large interlayer spacings is superior to that for small interlayer spacings due to the influence of stress waves.

An improved convolution perfectly matched layer for elastic second-order wave equation

A convolution perfectly matched layer(CPML)can efficiently absorb boundary reflection in numerical simulation.However,the CPML is suitable for the first-order elastic wave equation and is difficult to apply directly to the second-order elastic wave equation.In view of this,based on the first-order CPML absorbing boundary condition,we propose a new CPML(NCPML)boundary which can be directly applied to the second-order wave equation.We first systematically extend the first-order CPML technique into second-order wave equations,neglecting the space-varying characteristics of the partial damping coefficient in the complex-frequency domain,avoiding the generation of convolution in the time domain.We then transform the technique back to the time domain through the inverse Fourier transform.Numerical simulation indicates that the space-varying characteristics of the attenuation factor have little influence on the absorption effect and increase the memory at the same time.A number of numerical examples show that the NCPML proposed in this study is effective in simulating elastic wave propagation,and this algorithm is more efficient and requires less memory allocation than the conventional PML absorbing boundary.

Median Filtering Detection Based on Quaternion Convolutional Neural Network

Median filtering is a nonlinear signal processing technique and has an advantage in the field of image anti-forensics.Therefore,more attention has been paid to the forensics research of median filtering.In this paper,a median filtering forensics method based on quaternion convolutional neural network(QCNN)is proposed.The median filtering residuals(MFR)are used to preprocess the images.Then the output of MFR is expanded to four channels and used as the input of QCNN.In QCNN,quaternion convolution is designed that can better mix the information of different channels than traditional methods.The quaternion pooling layer is designed to evaluate the result of quaternion convolution.QCNN is proposed to features well combine the three-channel information of color image and fully extract forensics features.Experiments show that the proposed method has higher accuracy and shorter training time than the traditional convolutional neural network with the same convolution depth.

DISCRETE SINGULAR CONVOLUTION METHOD WITH PERFECTLY MATCHED ABSORBING LAYERS FOR THE WAVE SCATTERING BY PERIODIC STRUCTURES

A new computational algorithm is introduced for solving scattering problem in periodic structure. The PML technique is used to deal with the difficulty on truncating the unbounded domain while the DSC algorithm is utilized for the spatial discretization. The present study reveals that the method is efficient for solving the problem.

Ozone Depletion Identification in Stratosphere Through Faster Region-Based Convolutional Neural Network

The concept of classification through deep learning is to build a model that skillfully separates closely-related images dataset into different classes because of diminutive but continuous variations that took place in physical systems over time and effect substantially.This study has made ozone depletion identification through classification using Faster Region-Based Convolutional Neural Network(F-RCNN).The main advantage of F-RCNN is to accumulate the bounding boxes on images to differentiate the depleted and non-depleted regions.Furthermore,image classification’s primary goal is to accurately predict each minutely varied case’s targeted classes in the dataset based on ozone saturation.The permanent changes in climate are of serious concern.The leading causes beyond these destructive variations are ozone layer depletion,greenhouse gas release,deforestation,pollution,water resources contamination,and UV radiation.This research focuses on the prediction by identifying the ozone layer depletion because it causes many health issues,e.g.,skin cancer,damage to marine life,crops damage,and impacts on living being’s immune systems.We have tried to classify the ozone images dataset into two major classes,depleted and non-depleted regions,to extract the required persuading features through F-RCNN.Furthermore,CNN has been used for feature extraction in the existing literature,and those extricated diverse RoIs are passed on to the CNN for grouping purposes.It is difficult to manage and differentiate those RoIs after grouping that negatively affects the gathered results.The classification outcomes through F-RCNN approach are proficient and demonstrate that general accuracy lies between 91%to 93%in identifying climate variation through ozone concentration classification,whether the region in the image under consideration is depleted or non-depleted.Our proposed model presented 93%accuracy,and it outperforms the prevailing techniques.

Grid Side Distributed Energy Storage Cloud Group End Region Hierarchical Time-Sharing Configuration Algorithm Based onMulti-Scale and Multi Feature Convolution Neural Network

There is instability in the distributed energy storage cloud group end region on the power grid side.In order to avoid large-scale fluctuating charging and discharging in the power grid environment and make the capacitor components showa continuous and stable charging and discharging state,a hierarchical time-sharing configuration algorithm of distributed energy storage cloud group end region on the power grid side based on multi-scale and multi feature convolution neural network is proposed.Firstly,a voltage stability analysis model based onmulti-scale and multi feature convolution neural network is constructed,and the multi-scale and multi feature convolution neural network is optimized based on Self-OrganizingMaps(SOM)algorithm to analyze the voltage stability of the cloud group end region of distributed energy storage on the grid side under the framework of credibility.According to the optimal scheduling objectives and network size,the distributed robust optimal configuration control model is solved under the framework of coordinated optimal scheduling at multiple time scales;Finally,the time series characteristics of regional power grid load and distributed generation are analyzed.According to the regional hierarchical time-sharing configuration model of“cloud”,“group”and“end”layer,the grid side distributed energy storage cloud group end regional hierarchical time-sharing configuration algorithm is realized.The experimental results show that after applying this algorithm,the best grid side distributed energy storage configuration scheme can be determined,and the stability of grid side distributed energy storage cloud group end region layered timesharing configuration can be improved.

基于动态自适应图神经网络的电动汽车充电负荷预测

电动汽车充电站负荷波动的不确定性与长时间预测任务给提升充电负荷预测精度带来巨大的挑战。文中提出一种基于动态自适应图神经网络的电动汽车充电负荷预测算法。首先,构建了一个充电负荷信息时空关联特征提取层,将多头注意力机制与自适应相关图结合生成具有时空关联性的综合特征表达式,以捕获充电站负荷的波动性;然后,将提取的特征输入到时空卷积层,捕获时间和空间之间的耦合关系;最后,通过切比雪夫多项式图卷积与多尺度时间卷积提升模型耦合长时间序列之间的能力。以Palo Alto数据集为例,与现有方法相比,所提算法在4种波动情况下的平均预测误差大幅降低。

基于双层注意力和深度自编码器的时间序列异常检测模型

目前时间序列通常具有弱周期性以及高度复杂的相关性特征,传统的时间序列异常检测方法难以检测此类异常。针对这一问题,提出了一种新的无监督时间序列异常检测模型(DA-CBG-AE)。首先,使用新型滑动窗口方法,针对时间序列周期性设置滑动窗口大小;其次,采用卷积神经网络提取时间序列高维度空间特征;然后,提出具有堆叠式Dropout双向门循环单元网络作为自编码器的基本结构,从而捕捉时间序列的相关性特征;最后,引入双层注意力机制,进一步提取特征,选择更加关键的时间序列,从而提高异常检测准确率。为了验证该模型的有效性,将DA-CBG-AE与6种基准模型在8个数据集上进行比较。最终的实验结果表明,DA-CBG-AE获得了最优的F1值(0.863),并且其检测性能相比最新的基准模型Tad-GAN高出25.25%。

基于注意力机制与LSTM-CCN的月降水量预测

针对现有月降水量预测方法预测准确性不高的问题,提出一种基于注意力机制与LSTM-CCN的月降水量预测方法。首先,利用长短时记忆神经网络(long short-term memory neural network,LSTM)提取气象数据在时间维度的特征分布,从时间相关性方面捕获相邻时间段或长距离气象数据段中的统计分布;其次,利用因果卷积神经网络(causal convolutional network,CCN)将气象数据映射到空间维度,深层次地从空间维度捕获气象数据在空间中的特征统计分布;再次,以并联的方式将时间和空间特征作为交叉注意力网络的输入,构造融合的时空特征;最后,以长短时记忆神经网络构造解码器,并将融合的时空特征作为解码器的输入,预测的月降水量作为输出。选取河南省新乡市2001~2017年数据集进行测试,结果表明:所提出方法的均方根误差仅为13.08 mm,相比主流方法具有更低的预测误差。研究成果可为提高气象预测的准确性和实用性提供参考。

基于CNN-SVM模型的鸡蛋外观品质检测

[目的]提高鸡蛋外观品质检测的精度,建立CNN-SVM模型的鸡蛋外观品质检测模型。[方法]结合CNN的自适应特征提取功能和SVM的超强泛化分类性能,通过6层卷积神经网络结构处理提取全连接层的特征,采用CNN-SVM混合模型替代传统CNN+softmax,构建一个基于CNN-SVM模型的鸡蛋外观品质检测方法。[结果]与SVM模型、CNN模型和KNN模型相比,CNN-SVM模型在准确率、精确率、召回率和F1分数方面表现优异,分别为97.97%,98.10%,98.10%,98.00%。KNN模型在鸡蛋外观品质检测上的精度最低,其准确率、精确率、召回率和F1分数分别为77.46%,79.44%,76.75%,76.90%。[结论]CNN-SVM模型具有很强的鲁棒性和抗噪声能力,可以有效提高鸡蛋外观品质检测的准确性和适用性。

多尺度特征金字塔融合的街景图像语义分割

针对街景图像语义分割任务中的目标尺寸差异大、多尺度特征难以高效提取的问题,本文提出了一种语义分割网络(LDPANet).首先,将空洞卷积与引入残差学习单元的深度可分离卷积结合,来优化编码器结构,在降低了计算复杂度的同时缓解梯度消失的问题.然后利用层传递的迭代空洞空间金字塔,将自顶向下的特征信息依次融合,提高了上下文信息的有效交互能力;在多尺度特征融合之后引入属性注意力模块,使网络抑制冗余信息,强化重要特征.再者,以通道扩展上采样代替双线插值上采样作为解码器,进一步提升了特征图的分辨率.最后,LDPANet方法在Cityscapes和CamVid数据集上的精度分别达到了91.8%和87.52%,与近几年网络模型相比,本文网络模型可以精确地提取像素的位置信息以及空间维度信息,提高了语义分割的准确率.

基于多层卷积的红外与可见光图像融合算法

针对复杂背景下纹理细节信息丢失、融合图像视觉感受较差等问题,提出了一种基于多层卷积的红外与可见光图像融合算法。该算法的网络框架分为编码器、解码器和融合网络3个部分。在编码器中引入高效通道注意力机制对源图像进行编码处理,融合多层卷积块、梯度卷积块、下采样卷积块以及卷积空间通道注意力机制等形成多层卷积融合网络(MCFN),通过该融合网络进行特征融合,利用解码器重建输出融合图像。选取了5种现有算法与所提算法用8种客观评价指标在两种数据集上进行比较,结果表明,所提算法融合后的图像目标突出、细节清晰、轮廓明显、指标提升显著,符合人体视觉感受。

基于超分辨率图像重建的轻量化目标检测算法研究

利用面向边缘的卷积模块、像素注意力机制和重参数化技术使超分辨率重建算法图像分辨率得到提升,使图像特征细节表现更为优越;利用YOLOv4目标检测算法并结合Focus结构、双向特征金字塔网络和轻量级子通道注意力机制,提高中、低分辨率图像目标检测精度。经实验研究,基于超分辨率重建的轻量化目标检测算法对图像目标具有较好的检测效果,有效提升了图像的检测精度,对提升图像中的细小目标检测精度具有一定的参考意义。

基于图神经网络的多层银企网络融合研究

针对金融行业内潜在系统性风险难以精准识别问题,基于直接系统性风险传染渠道的借贷数据以及间接渠道的互联网文本信息,构建多层银企网络,并利用图卷积神经网络(GCN)设计多层银企网络融合模型,根据融合网络量化评估29家银行和75家房地产机构的不同渠道系统性风险传染过程。实验结果表明,在多层金融网络融合任务上,本文融合模型的准确率达到0.8559,优于对比模型。融合网络分析表明,多层网络共同冲击下的银企系统性风险传染能力明显大于单一或者2层网络的系统性风险,且基于间接渠道的企业间网络系统性风险更明显。金融审慎监管应该更多关注文本数据、深度学习等技术对于整合庞大金融资源的能力和有效提高风险监测预警的能力。

基于CNN-LSTM电力消耗预测模型及系统开发

有效预测电能负荷,对提高电力负荷时间序列测量准确度及合理制定用电能管理措施具有重要意义。针对传统预测模型在电能负荷预测中无法充分挖掘时间序列数据中隐藏特征的问题,基于电能数据时间序列的趋势,融合数值信息提出一种卷积神经网络(convolutional neuralnetwork,CNN)与长期短期记忆循环神经网络(long short-term memory network,LSTM)相结合的混合多隐层CNN-LSTM电力能耗预测模型。首先,通过设定最小目标函数作为优化目标,Adam优化算法更新神经网络的权重,并对网络层和批大小进行自适应调优以确定最佳层数和批大小。其次,构建混合多隐层模型并进行隐层组合优化与讨论,确定最佳时间维度的参数,进行时间维度的特征学习进而预测下一时间序列的耗电量。然后以某公司的电力负荷数据为例进行验证,并与LSTM、CNN、RNN等模型的预测结果分析比较。结果表明上述混合多隐层模型预测准确度达98.94%,平均绝对误差(MAE)达到0.0066,均优于其他相关模型,证明以上混合预测模型在电力负荷预测精度方面具有更好的性能。基于上述理论,开发了能耗监控决策系统,实现设备状态实时监控和能耗智能预测功能,为解决传统制造业能耗需求不精确和能源库存浪费问题提供参考和指导。

基于改进注意力机制的时间卷积网络-长短期记忆网络短期电力负荷预测

为充分挖掘蕴含在电力负荷数据中的有效时序信息,提高短期电力负荷预测准确度,本文提出一种基于改进注意力机制的时间卷积网络(TCN)-长短期记忆(LSTM)网络负荷预测模型。首先,将时序数据输入TCN模型中进行时序特征提取;然后,将所提取的时序特征与非时序数据组合,并输入LSTM模型中进行训练;最后,采用贝叶斯优化方法进行超参数寻优以获得TCN-LSTM模型的最优参数,引入通过多层感知器(MLP)改进的注意力机制以减少历史信息丢失并加强重要信息的影响,完成短期负荷预测。通过对比多种深度学习模型的预测效果表明,本文所提模型的短期电力负荷预测准确度更高。

基于Zynq平台的低功耗人脸检测加速系统

基于CPU及GPU的卷积神经网络平台存在体积大、能耗高等问题,提出了一种基于Zynq平台的卷积神经网络人脸检测加速系统。该系统采用YOLOv3-Tiny算法,并利用Wider Face人脸数据集进行训练。为提高网络效率,采用层融合技术减小网络深度,加快检测速度;同时,采用8位整数量化策略,以降低内存访问量,减少资源消耗。通过利用ZynqXC7Z035芯片上FPGA端并行计算能力,设计出可重复利用的多通道卷积计算模块,实现DSP的重复递用。实验结果显示,所设计的加速系统实现了9.5FPS的实时推理速度,检测速度是intel i7-8700CPU的7.9倍,系统功耗仅为2.65W,满足低功耗的性能需求。

基于CNN跨层融合结构的边缘检测算法

传统边缘检测算法难以处理复杂的图像,而现有基于深度的边缘检测模型,其检测结果往往存在边缘定位错误和信息丢失等现象.针对此类问题,提出一种基于RCF的高精度的边缘检测算法RCF-CLF.首先,引入HDC结构设计用于避免因叠加相同膨胀卷积而引起的网格效应;其次,设计了一种特征增强结构,旨在融合多尺度信息、扩大感受野;然后,设计了跨层融合结构,将高层信息和低层信息融合,用于提取准确的边缘信息;最后,引入注意力机制CBAM,通过聚焦物体边缘区域,抑制非边缘区域,从而提高网络对边缘信息的提取能力.本文在BSDS500和BIPED数据集上评估所提出的方法,与RCF算法相比,在BIPED数据集上,主要指标ODS、OIS和AP分别达到了0.893、0.901和0.945,提高了近5个百分点,在BSDS500数据集上,主要指标也有所提升.此外,与其他同类算法相比,本文算法也具有一定的优势,可以实现更加准确的边缘定位.