Optimization Design of the Multi-Layer Cross-Sectional Layout of An Umbilical Based on the GA-GLM

Marine umbilical is one of the key equipment for subsea oil and gas exploitation,which is usually integrated by a great number of different functional components with multi-layers.The layout of these components directly affects manufacturing,operation and storage performances of the umbilical.For the multi-layer cross-sectional layout design of the umbilical,a quantifiable multi-objective optimization model is established according to the operation and storage requirements.Considering the manufacturing factors,the multi-layering strategy based on contact point identification is introduced for a great number of functional components.Then,the GA-GLM global optimization algorithm is proposed combining the genetic algorithm and the generalized multiplier method,and the selection operator of the genetic algorithm is improved based on the steepest descent method.Genetic algorithm is used to find the optimal solution in the global space,which can converge from any initial layout to the feasible layout solution.The feasible layout solution is taken as the initial value of the generalized multiplier method for fast and accurate solution.Finally,taking umbilicals with a great number of components as examples,the results show that the cross-sectional performance of the umbilical obtained by optimization algorithm is better and the solution efficiency is higher.Meanwhile,the multi-layering strategy is effective and feasible.The design method proposed in this paper can quickly obtain the optimal multi-layer cross-sectional layout,which replaces the manual design,and provides useful reference and guidance for the umbilical industry.

A flexible ultra-broadband multi-layered absorber working at 2 GHz-40 GHz printed by resistive ink

A flexible extra broadband metamaterial absorber(MMA)stacked with five layers working at 2 GHz–40 GHz is investigated.Each layer is composed of polyvinyl chloride(PVC),polyimide(PI),and a frequency selective surface(FSS),which is printed on PI using conductive ink.To investigate this absorber,both one-dimensional analogous circuit analysis and three-dimensional full-wave simulation based on a physical model are provided.Various crucial electromagnetic properties,such as absorption,effective impedance,complex permittivity and permeability,electric current distribution and magnetic field distribution at resonant peak points,are studied in detail.Analysis shows that the working frequency of this absorber covers entire S,C,X,Ku,K and Ka bands with a minimum thickness of 0.098λ_(max)(λ_(max) is the maximum wavelength in the absorption band),and the fractional bandwidth(FBW)reaches 181.1%.Moreover,the reflection coefficient is less than-10 dB at 1.998 GHz–40.056 GHz at normal incidence,and the absorptivity of the plane wave is greater than 80%when the incident angle is smaller than 50°.Furthermore,the proposed absorber is experimentally validated,and the experimental results show good agreement with the simulation results,which demonstrates the potential applicability of this absorber at 2 GHz–40 GHz.

Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable

One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural networks(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural networks are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural networks like the multi-layer perceptron(MLP)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading histories.In this work,one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLP model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular materials.The obtained ML models are then seamlessly embedded into the FEM to solve the BVP of a biaxial compression case and a rigid strip footing case.The obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved efficiency.The results demonstrate the applicability of the proposed internal variable in enabling MLP to capture highly nonlinear constitutive responses of granular materials.

Dynamic interwell connectivity analysis of multi-layer waterflooding reservoirs based on an improved graph neural network

The analysis of interwell connectivity plays an important role in the formulation of oilfield development plans and the description of residual oil distribution. In fact, sandstone reservoirs in China's onshore oilfields generally have the characteristics of thin and many layers, so multi-layer joint production is usually adopted. It remains a challenge to ensure the accuracy of splitting and dynamic connectivity in each layer of the injection-production wells with limited field data. The three-dimensional well pattern of multi-layer reservoir and the relationship between injection-production wells can be equivalent to a directional heterogeneous graph. In this paper, an improved graph neural network is proposed to construct an interacting process mimics the real interwell flow regularity. In detail, this method is used to split injection and production rates by combining permeability, porosity and effective thickness, and to invert the dynamic connectivity in each layer of the injection-production wells by attention mechanism.Based on the material balance and physical information, the overall connectivity from the injection wells,through the water injection layers to the production layers and the output of final production wells is established. Meanwhile, the change of well pattern caused by perforation, plugging and switching of wells at different times is achieved by updated graph structure in spatial and temporal ways. The effectiveness of the method is verified by a combination of reservoir numerical simulation examples and field example. The method corresponds to the actual situation of the reservoir, has wide adaptability and low cost, has good practical value, and provides a reference for adjusting the injection-production relationship of the reservoir and the development of the remaining oil.

Target layer state estimation in multi-layer complex dynamical networks considering nonlinear node dynamics

In many engineering networks, only a part of target state variables are required to be estimated.On the other hand,multi-layer complex network exists widely in practical situations.In this paper, the state estimation of target state variables in multi-layer complex dynamical networks with nonlinear node dynamics is studied.A suitable functional state observer is constructed with the limited measurement.The parameters of the designed functional observer are obtained from the algebraic method and the stability of the functional observer is proven by the Lyapunov theorem.Some necessary conditions that need to be satisfied for the design of the functional state observer are obtained.Different from previous studies, in the multi-layer complex dynamical network with nonlinear node dynamics, the proposed method can estimate the state of target variables on some layers directly instead of estimating all the individual states.Thus, it can greatly reduce the placement of observers and computational cost.Numerical simulations with the three-layer complex dynamical network composed of three-dimensional nonlinear dynamical nodes are developed to verify the effectiveness of the method.

Multi-layer phenomena in petawatt laser-driven acceleration of heavy ions

Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW laser-accelerated heavy particles using different nanoscale short targets with a thickness of 100 nm Cr, Fe, Ag, Ta, Au, Pb, Th and U, as well as 200 nm thick Al and Ca. An obvious stratification is observed in the simulation. The layering phenomenon is a hybrid acceleration mechanism reflecting target normal sheath acceleration and radiation pressure acceleration, and this phenomenon is understood from the simulated energy spectrum,ionization and spatial electric field distribution. According to the stratification, it is suggested that high-quality heavy-ion beams could be expected for fusion reactions to synthesize superheavy nuclei. Two plasma clusters in the stratification are observed simultaneously, which suggest new techniques for plasma experiments as well as thinner metal targets in the precision machining process.

PCB可靠性测试评估方法简述

印制电路板(PCB)技术向高密度、高集成化等方向发展,导致PCB可靠性问题日益凸显。针对PCB失效机理,并结合现有PCB标准及实践应用情况,详细介绍了3种PCB可靠性测试评估的方法——失效率预计法、加速试验预计法和试验鉴定法,以期为从业者开展PCB可靠性测试评估提供一定的帮助。

高功率微波电磁脉冲对铁路PCB类设备的危害影响及防护措施研究

随着我国铁路朝着电气化和信息化方向不断发展,各种由精密PCB设计集成的电力电子设备广泛应用于各种强弱电系统,当这些设备遭受高功率微波等强电磁脉冲武器照射攻击时,若自身防护能效不足,则会导致设备出现异常状态,直接或间接地影响行车安全。文章通过建模仿真分析高功率微波电磁脉冲对铁路PCB设备的辐射影响和危害评估,并从工程角度提出了一些针对铁路PCB设备应对强电磁冲击的防护建议。

TIA组态控制功能在PCB组装工艺中的应用

针对印刷电路板(PCB)组装工艺装贴方式多样,生产线工艺切换需要改变硬件组态和优化工艺流程,导致生产线停机时间加长、维护成本升高、生产效率降低等问题。以西门子PLC和分布式IO模块为例,提出了组态控制功能在PCB组装系统中的应用方案。采用最大硬件方案组态形成标准机器项目。根据不同的生产工艺、不同的生产方案,存储在专门的组态控制数据块中。当需要切换PCB组装工艺时,加载相应的组态方案,就可以运行新的组态项目和生产工艺,达到快速完成生产工艺切换的目的。使用西门子TIA博途V17的仿真检验,验证了组态控制功能的有效性和可靠性。

Blast wave characteristics of multi-layer composite charge:Theoretical analysis,numerical simulation,and experimental validation

This article investigates the characteristics of shock wave overpressure generated by multi-layer composite charge under different detonation modes.Combining dimensional analysis and the explosion mechanism of the charge,a peak overpressure prediction model for the composite charge under singlepoint detonation and simultaneous detonation was established.The effects of the charge structure and initiation method on the overpressure field characteristics were investigated in AUTODYN simulation.The accuracy of the prediction model and the reliability of the numerical simulation method were subsequently verified in a series of static explosion experiments.The results reveal that the mass of the inner charge was the key factor determining the peak overpressure of the composite charge under single-point detonation.The peak overpressure in the radial direction improved apparently with an increase in the aspect ratio of the charge.The overpressure curves in the axial direction exhibited a multi-peak phenomenon,and the secondary peak overpressure even exceeded the primary peak at distances of 30D and 40D(where D is the charge diameter).The difference in peak overpressure among azimuth angles of 0-90°gradually decreased with an increase in the propagation distance of the shock wave.The coupled effect of the detonation energy of the inner and outer charge under simultaneous detonation improved the overpressure in both radial and axial directions.The difference in peak overpressure obtained from model prediction and experimental measurements was less than 16.4%.

基于轻量化的YOLOv5的PCB缺陷检测算法

针对在印刷电路板(printed circuit board,PCB)缺陷检测上网络模型过大且精度较低的缺点,使用Python在Windows上提出了一种基于YOLOv5l改进的PCB缺陷检测算法,并对六种常见的缺陷作为数据集进行检测。采用轻量化网络EfficientNetLite0作为模型的骨干网络﹐并通过对特征金字塔加入P2检测头来获取更小的目标特征。试验结果表明:所提算法对印刷电路板的缺陷有识别精度高、模型小和检测快速的特点;单张图片检测速度达到43.6 ms﹐模型大小为49.1 MB﹐所有类别精度指标达到98.9%。所提算法为未来部属在边缘设备上的工业缺陷检测提供了新思路。

基于融合MBAM与YOLOv5的PCB缺陷检测方法

随着电子信息产业迅速发展,PCB行业作为电子信息产业的基础,其产品质量对后续生产的电子产品有着决定性影响。针对PCB缺陷目标较小,缺陷类型多,特征不明显,在实际生产过程中易产生误检、漏检等问题,提出了一种多分支注意力MBAM模块方法,在3个不同维度对特征图进行关注,以增强特征提取的能力,对缺陷区域给予更多的注意力表示。通过改进YOLOv5结构,将MBAM与YOLOv5网络结合,有效的提升了对PCB中小目标的检测性能。最后通过在网络不同位置添加MBAM模块进行对比实验,选取了最佳的添加位置。通过在PCB缺陷数据集上的实验结果表明,改进后的PCB缺陷检测算法具有良好的检测性能,优于其他对比算法,最终的AP达到了96.7%,对比标准YOLOv5的94.7%提高了2个百分点,其他项指标均有涨点,在保持检测速度基本不变的情况下,精准地识别PCB缺陷类型。

Optimizing slope safety factor prediction via stacking using sparrow search algorithm for multi-layer machine learning regression models

The safety factor is a crucial quantitative index for evaluating slope stability.However,the traditional calculation methods suffer from unreasonable assumptions,complex soil composition,and inadequate consideration of the influencing factors,leading to large errors in their calculations.Therefore,a stacking ensemble learning model(stacking-SSAOP)based on multi-layer regression algorithm fusion and optimized by the sparrow search algorithm is proposed for predicting the slope safety factor.In this method,the density,cohesion,friction angle,slope angle,slope height,and pore pressure ratio are selected as characteristic parameters from the 210 sets of established slope sample data.Random Forest,Extra Trees,AdaBoost,Bagging,and Support Vector regression are used as the base model(inner loop)to construct the first-level regression algorithm layer,and XGBoost is used as the meta-model(outer loop)to construct the second-level regression algorithm layer and complete the construction of the stacked learning model for improving the model prediction accuracy.The sparrow search algorithm is used to optimize the hyperparameters of the above six regression models and correct the over-and underfitting problems of the single regression model to further improve the prediction accuracy.The mean square error(MSE)of the predicted and true values and the fitting of the data are compared and analyzed.The MSE of the stacking-SSAOP model was found to be smaller than that of the single regression model(MSE=0.03917).Therefore,the former has a higher prediction accuracy and better data fitting.This study innovatively applies the sparrow search algorithm to predict the slope safety factor,showcasing its advantages over traditional methods.Additionally,our proposed stacking-SSAOP model integrates multiple regression algorithms to enhance prediction accuracy.This model not only refines the prediction accuracy of the slope safety factor but also offers a fresh approach to handling the intricate soil composition and other influencing factors,making it a precise and reliable method for slope stability evaluation.This research holds importance for the modernization and digitalization of slope safety assessments.

磁沉淀工艺在PCB印制线路板废水处理中的应用

广东某PCB印制线路板园区集中污水处理站设计水量为12000 m^(3)/d,总磷排放标准为0.5 mg/L,由于污水中含有部分次磷,深度处理采用芬顿氧化澄清工艺。该污水处理站地处工业园核心区,用地紧张,芬顿氧化配套的常规澄清池由于面积不足,存在漂泥情况,TP和SS难以稳定达标。根据现场情况,将现有的澄清池改造为磁沉淀高效澄清池,提高芬顿氧化出水净化指标。长期运行结果表明:磁沉淀工艺对PCB印制线路板废水芬顿氧化出水具有良好的澄清效果,在进水悬浮物浓度≤1000 mg/L,总磷≤2.0 mg/L时,出水悬浮物浓度≤30 mg/L,总磷≤0.5 mg/L,磁沉淀系统占地面积76 m^(2),沉淀表面负荷≥12.5 m^(3)/(m^(2)·h),处理水量峰值可达15000 m^(3)/d,运行电耗成本0.042元/t水,运行磁粉损耗成本为0.0113元/t水,自动化运行程度高,水质波动适应性强,出水稳定。

基于深度学习的PCB焊锡缺陷检测

针对现有印刷电路板(PCB)缺陷检测算法具有体积大、精度差和漏检率高等问题,提出一种改进的YOLOv5s算法,利用迁移学习进行优化。在主干特征提取网络加入卷积块注意力模块(Convolutional Block Attention Module,CBAM)并引出一个新的蕴含更多丰富细节信息的浅层特征来提高模型信息感知能力,增强网络对小目标的检测。使用C3-CBAM替换加强特征提取网络的C3结构,为了在保障模型检测精度的同时减少模型参数量,使用深度可分离卷积替换下采样。去掉用于大目标的检测头(Yolo Head),避免数据不均衡带来的先验框分配问题。在自制PCB焊锡缺陷数据集上实验表明,改进后算法较原YOLOv5s算法的模型参数量减少24.8%,平均精度均值(mean Average Precision,mAP)达到99.46%,较原YOLOv5s提升了5.45%,证明了改进措施的有效性。

基于注意力机制与多尺度融合的PCB缺陷检测

针对印制电路板(PCB)缺陷区域受背景干扰过多以及缺陷目标尺度较小导致缺陷检测精度低的问题,提出了一种基于注意力机制与多尺度融合的PCB缺陷检测方法。在YOLOv5模型的特征提取网络中,引入一种三维注意力模块,以增强缺陷目标特征的显著度,使模型更加注重目标特征;为充分利用微小缺陷目标的多尺度特征,在特征融合网络中引入加权双向特征金字塔网络(Bi-directional Feature Pyramid Network, BiFPN),减少缺陷目标特征信息的丢失,提高模型对微小缺陷目标的检测精度。实验结果表明,该方法能够准确检测出PCB图像中的缺陷目标,在保证实时性的同时,较原方法的平均检测精度提高了3.9%,表明了该方法的有效性。

基于改进YOLOv8n的PCB缺陷检测算法

针对现有的印刷电路板(PCB)缺陷检测方法计算量大、小目标缺陷易漏检、检测速度较慢等问题,提出YOLOv8n-4SCDP缺陷检测算法。首先,在YOLOv8n颈部网络增加上采样,融合Backbone中浅层语义信息,同时增加微小目标检测层降低PCB小目标缺陷漏检率;其次,在Backbone中融入坐标注意力(CA)机制,强化特征语义和位置信息,提高了模型特征融合能力;另外,设计密集连接机构,提高模型的缺陷特征利用率,采用PConv对模型进行压缩,既保证了模型的准确性,又大大减小了模型的尺寸;最后,针对难易样本不平衡的问题,采用线性区间映射法重新定义回归损失函数(Focaler-SIoU),提高模型收敛速度和回归精度。实验结果表明,YOLOv8n-4SCDP算法的整体缺陷的平均精度均值(mAP)达到95.8%,检测帧率达到了65fps。有效改善YOLOv8n对于PCB小目标缺陷漏检率高、检测精度低等问题。

基于热带海洋大气环境下机载PCB板的环境适应性对比研究

目的 通过机载PCB板(Printed Circuit Board,PCB)在热带海洋大气环境下的腐蚀老化特征和电气性能退化规律分析,研究其在热带海洋大气环境下的环境适应性。方法 根据热带海洋大气环境中PCB板的实际使用环境大多为舱室内部封闭或半封闭的情况,分别设计并开展海南万宁海洋平台棚下暴露场和某海域环境户外简易遮蔽玻璃框下3 a的自然环境试验。结果 PCB板的焊点、焊盘、印制导线以及引线头等部位在2种试验环境中均出现了不同程度的腐蚀破坏,试验后期,所有部位的腐蚀程度全部达到了4级,导通电阻从几十毫欧增大至几十兆欧,绝缘电阻从10 G?以上降低至几兆欧。结论 在万宁站试验2 a和某海域试验3 a后,PCB板均不满足耐电压的技术要求(500 V交流电压60 s),万宁海洋平台棚下暴露场对PCB板的环境适应性更为严酷。

Explosive synchronization of multi-layer complex networks based on star connection between layers with delay

Explosive synchronization(ES)is a kind of first-order jump phenomenon that exists in physical and biological systems.In recent years,researchers have focused on ES between single-layer and multi-layer networks.Most research on complex networks with delay has focused on single-layer or double-layer networks,multi-layer networks are seldom explored.In this paper,we propose a Kuramoto model of frequency weights in multi-layer complex networks with delay and star connections between layers.Through theoretical analysis and numerical verification,the factors affecting the backward critical coupling strength are analyzed.The results show that the interaction between layers and the average node degree has a direct effect on the backward critical coupling strength of each layer network.The location of the delay,the size of the delay,the number of network layers,the number of nodes,and the network topology are revealed to have no direct impact on the backward critical coupling strength of the network.Delay is introduced to explore the influence of delay and other related parameters on ES.

基于YOLOv5的PCB缺陷检测算法研究

针对PCB中存在的缺陷对象较小、类型较多、难以识别等问题,拟提出改进YOLOv5算法,以实现对该问题的有效处理。首先引入SEnet,通过学习,实现对各特征信道的重要性的自动提取,提高物体检测的精度。然后将解耦头思想引入到YOLOv5网络中,以提高故障检测的准确率并加速网络的收敛。实验结果显示,改进后YOLOv5算法的mAP@5值达到了92.5%,mAP@0.5:0.95值达到了47.5%,比原始分别提高了4.3%和2%。此外,每一种类型缺陷的精度都有了显著的提高,证明了算法的有效性。