Positioning-control Based on Trapezoidal Velocity Curve for High-precision Basis Weight Control Valve

Traditionally, basis weight control valve is driven by a constant frequency pulse signal. Therefore, it is difficult for the valve to match the control precision of basis weight. Dynamic simulation research using Matlab/Simulink indicates that there is much more overshoot and fluctuating during the valve-positioning process. In order to improve the valve-positioning precision, the control method of trapezoidal velocity curve was studied. The simulation result showed that the positioning steady-state error was less than 0.0056%, whereas the peak error was less than 0.016% by using trapezoidal velocity curve at 10 positioning steps. A valve-positioning precision experimental device for the stepper motor of basis weight control valve was developed. The experiment results showed that the error ratio of 1/10000 positioning steps was 4% by using trapezoidal velocity curve. Furthermore, the error ratio of 10/10000 positioning steps was 0.5%. It proved that the valve-positioning precision of trapezoidal velocity curve was much higher than that of the constant frequency pulse signal control strategy. The new control method of trapezoidal velocity curve can satisfy the precision requirement of 10000 steps.

Equivalence of String Classical and Quantum Energy beside Equivalence of Wave Packet and Relativistic Velocity in Eucleadian and Curved Space

Plank quantum and classical string energy relations seem to be uncorrelated. This work correlated them. The relativistic energy-momentum relation has been used together with plank and de Brogglie hypothesis to prove that the wave group velocity is equal to the particle velocity in both ordinary and curved space. The plank energy relation is shown also to be related to the classical energy relation of an oscillating string. Starting from plank energy relation for n photons and performing integration, the expression of classical string energy was obtained. This means that one can treat electromagnetic waves as a collection of continuous photons having frequencies ranging from zero to w. Conversely, starting from classical string energy relation by differentiating it with respect to angular frequency, the plank quantum energy for n photons has been found. This means that the quanta results from separation of electromagnetic waves to single isolated waves. Each wave consists of n photons or quanta.

Conformal Multi-resolution Time-Domain Method for Scattering Curved Dielectric Objects

A conformal multi-resolution time-domain( CMRTD) method is presented for modeling curved objects. The effective dielectric constant and area weighting are used to derive the update equations of CMRTD. The backward scattering bistatic radar cross sections( RCS) of the dielectric cylinder and ellipsoid are used to validate the proposed method. The results show that the proposed conformal method is more accurate to deal with the complex curved objects in electromagnetic simulations.

Finite-difference time-domain modeling of curved material interfaces by using boundary condition equations method

To deal with the staircase approximation problem in the standard finite-difference time-domain（FDTD） simulation,the two-dimensional boundary condition equations（BCE） method is proposed in this paper.In the BCE method,the standard FDTD algorithm can be used as usual,and the curved surface is treated by adding the boundary condition equations.Thus,while maintaining the simplicity and computational efficiency of the standard FDTD algorithm,the BCE method can solve the staircase approximation problem.The BCE method is validated by analyzing near field and far field scattering properties of the PEC and dielectric cylinders.The results show that the BCE method can maintain a second-order accuracy by eliminating the staircase approximation errors.Moreover,the results of the BCE method show good accuracy for cylinder scattering cases with different permittivities.

Theoretical Model for Calculating Electric-Power Curves Depicting Accelerated Flyer by Exploding Foil

A theoretical model for calculating electric-power curves of small-size foil during its electrical explosion is given.This technique is based on temperature dependence of foil conductivity.After taking into account the energy conversion of the foil explosion,the power-time curve is applied to the hydrodynamic code.One-dimensional numerical simulations of electric-explosion driving flyers are performed using this code.Calculated flyer velocities lie within ±8% of experimental data from Lawrence Livermore National Laboratory （LLNL）,and simulated history curves of flyer velocities coincide well with those measured using velocity interferometer system for any reflector （VISAR）,indicating a helpful work for design optimization of slapper detonators.

Integrative method in lithofacies characteristics and 3D velocity volume of the Permian igneous rocks in H area, Tarim Basin

This paper introduces horizon control, seismic control, logging control and facies control methods through the application of the least squares fitting of logging curves, seismic inversion and facies-controlled techniques. Based on the microgeology and thin section analyses, the lithology, lithofacies and periods of the Permian igneous rocks are described in detail. The seismic inversion and facies-controlled techniques were used to find the distribution characteristics of the igneous rocks and the 3D velocity volume. The least squares fitting of the logging curves overcome the problem that the work area is short of density logging data. Through analysis of thin sections, the lithofacies can be classified into eruption airfall subfacies, eruption pyroclastic flow subfacies and eruption facies.

The Body Wave Velocity Structure in the Upper Crust of Fujian Estimated by Noise Records

In this paper,the dispersion curves of the Rayleigh wave and Love wave were extracted from the seismic noise records of 25 broadband stations of the Fujian Seismic Network, and inverted for the lithosphere velocity structure. Furthermore,the velocity model was verified by the seismic explosion observations. Our results indicate that the resolution of the lithosphere velocity structure obtained by this method is good in the shallow part,but in the deep part,inversion accuracy for the wave velocity structure is low,which is caused mainly by the small inter-station distance chosen in the paper. Thus the wave dispersion curves have high accuracy in the short-period part,but the warp of the wave dispersion curve in long-period part is large. Considering the results from both the noise inversion and the traditional inversion,we finally present a new velocity model,and the theoretical travel time calculated with the new model matches the explosion travel time very well.

Studies on phase and group velocities from acoustic logging

It is still argued whether we measure phase or group velocities using acoustic logging tools. In this paper, three kinds of models are used to investigate this problem by theoretical analyses and numerical simulations. First, we use the plane-wave superposition model containing two plane waves with different velocities and able to change the values of phase velocity and group velocity. The numerical results show that whether phase velocity is higher or lower than group velocity, using the slowness-time coherence （STC） method we can only get phase velocities. Second, according to the results of the dispersion analysis and branch-cut integration, in a rigid boundary borehole model the results of dispersion curves and the waveforms of the first-order mode show that the velocities obtained by the STC method are phase velocities while group velocities obtained by arrival time picking. Finally, dipole logging in a slow formation model is investigated using dispersion analysis and real-axis integration. The results of dispersion curves and full wave trains show similar conclusions as the borehole model with rigid boundary conditions.

地震波泄漏模式研究进展

地震波在层状结构中传播时会产生频散现象,基于频散曲线特征可以反演地下速度结构.利用从地震记录和背景噪声中提取的面波频散曲线进行反演已经成为研究近地表和岩石圈结构的重要方法.除面波外,近年来学者们在泄漏模式及其频散的研究和应用方面取得了重要进展.泄漏模式可以为速度结构反演提供包括纵波速度在内的约束信息,能够与面波频散反演优势互补,实现更准确、全面的速度建模.但相比于面波,地震信号和背景噪声中的泄漏模式振幅通常较弱,因此提取泄漏模式信息对观测技术具有较高要求;另一方面,研究泄漏模式需要更复杂的理论基础和数值求解技术,所以在过去几十年间泄漏模式并未受到太多关注.数十年来,泄漏模式理论已随着地震学、光学和声学的相关研究而日趋完善,并形成了有效的数值计算方法和工具,这为泄漏模式的实际应用奠定了重要基础.而随着高质量、高密度观测数据的增多以及数据处理技术的进步,学者们已成功从各类型数据(天然及人工地震、背景噪声等)中提取到了泄漏模式信息,并发展了基于泄漏模式的速度结构成像方法.目前该成像方法已成功应用于天然地震、背景噪声和勘探地震的速度建模,具有较好的应用前景.本文首先介绍了泄漏模式的理论基础和数值计算方法,并从敏感性角度阐述了泄漏模式对速度建模的意义;随后本文通过回顾代表性的研究介绍了泄漏模式观测和应用方面的重要进展,并对已提出的几种反演手段进行了比较和分析;最后,本文还对泄漏模式在地震成像中的关键问题进行了分析和讨论.

Near-surface velocity estimation using shear-waves and deep-learning with a U-net trained on synthetic data

Estimation of good velocity models under complex near-surface conditions remains a topic of ongoing research.We propose to predict near-surface velocity profiles from surface-waves transformed to phase velocity-frequency panels in a data-driven manner using deep neural networks.This is a different approach from many recent works that attempt to estimate velocity from directly reflected body waves or guided waves.A secondary objective is to analyze the influence on the prediction accuracy of various commonly employed deep learning practices,such as transfer learning and data augmentations.Through numerical experiments on synthetic data as well as a real geophysical example,we demonstrate that transfer learning as well as data augmentations are helpful when using deep learning for velocity estimation.A third and final objective is to study lack of generalization of deep learning models for out-of-distribution(OOD)data in the context of our problem,and present a novel approach to tackle it.We propose a domain adaptation network for training deep learning models that uses a priori knowledge on the range of velocity values in order to constrain mapping of the output.The final comparison on field data,which was not part of the training data,show the deep neural network predictions compare favorably with a conventional velocity model estimation obtained with a dispersion curve inversion workflow.

基于平均速度分析的近地表纵波速度反演

面波频散曲线对于横波速度、纵波速度、层厚等近地表地球物理参数的敏感度相差较大,现阶段通过频散曲线可以获得较为精确的近地表横波速度与厚度信息,但无法直接对纵波速度进行反演.研究表明,泊松比对于波长(W)-探测深度(D)关系较为敏感.基于这一发现,本文根据频散曲线与反演获取的横波速度结构计算平均速度,获取W-D关系曲线.但合成数据测试证明,因近地表浅层对应的W-D曲线变化较小,且浅层纵波速度反演不准确会使误差累积,直接反演W-D曲线无法获取可靠的纵波速度剖面.本文改进了基于平均速度分析的近地表纵波速度反演方法,在目标函数中加入了对浅层信息较为敏感的W/D-D信息,同时对W-D曲线与W/D-D曲线进行联合反演.合成数据测试证明可以获取较为准确地浅层与深层纵波速度.将该方法应用于实际地震数据中,联合反演得到的纵波速度剖面与微测井数据较为吻合,证明本文提出的方法可以不借助其他信息,仅通过面波频散信息,获取更为准确地近地表纵波信息.

基于剪切波速的砂土液化临界公式

利用Kayen等收集的地震现场液化资料,以双曲线和幂函数为基础,提出了基于剪切波速的砂土液化临界公式。将临界公式和国内3种代表性判别方法对比分析,检验其液化判别效果。通过振动三轴液化试验,验证了液化临界公式下延至深层的适用性。结果表明:临界公式优化了判别成功率,其液化判别成功率达95%以上,非液化判别成功率可接受,同时避免在低烈度不安全而高烈度过于保守等现象。试验验证了本文临界曲线判别深度可下延至20 m以深。临界公式可作为现行规范的一种补充性和替代性的液化判别方法。

早发型重度子痫前期孕妇胎儿主肺动脉多普勒流速曲线参数的变化及意义

目的探讨早发型重度子痫前期孕妇胎儿主肺动脉多普勒流速曲线参数的变化及其对胎儿肺成熟度的预测价值。方法选取30例早发型重度子痫前期孕妇设为研究组,并根据新生儿结局的不同将其进一步分为呼吸窘迫综合征(RDS)组17例和非RDS组13例,另选取同期产检的80名正常妊娠孕妇设为正常对照组。比较各组孕妇胎儿主肺动脉多普勒流速曲线参数,并分析各参数对新生儿RDS的预测价值。结果研究组孕妇胎儿收缩期加速时间(AT)、收缩期射血时间(ET)短于对照组,收缩期加速时间与射血时间比值(AT/ET)低于对照组,差异有统计学意义(P<0.05);RDS组孕妇胎儿AT、ET短于非RDS组,差异有统计学意义(P<0.05),但2组AT/ET差异无统计学意义(P>0.05)。二元Logistic回归分析结果显示,三者联合预测新生儿RDS的方程为logit(P)=AT+(-0.560/1.048)×ET+(-2.464/1.048)×AT/ET。受试者工作特征曲线分析结果显示,AT、ET、AT/ET单独及联合预测新生儿RDS的曲线下面积分别为0.837、0.877、0.712及0.929,敏感度分别为94.1%、94.1%、47.1%及94.1%,特异度分别为58.1%、75.3%、84.9%及78.5%。结论早发型重度子痫前期孕妇胎儿主肺动脉多普勒流速曲线参数AT、ET、AT/ET数值均降低,应用多普勒超声监测胎儿的主肺动脉流速曲线能够有效评估其肺成熟度。

铝合金型材挤压弯曲一体化成形技术研究进展

相比于直型材,铝合金弯曲型材更适用于日益复杂的部件形状并能更好地满足轻量化需求,具有提升部件结构强度和刚度、节约空间及增加工业设计自由度等优点,在汽车、高铁和航空航天等领域具有广泛用途。相较于传统冷弯成形技术,挤压弯曲一体化成形技术在生产弯曲型材方面具有流程短、精度高、缺陷少等优点,因而受到广泛关注。重点综述了基于外部弯曲装置和材料差速流动的挤压弯曲一体化成形技术的研究进展,分析并总结了不同挤压弯曲一体化成形技术的原理及发展现状,对比了不同挤压弯曲一体化成形技术的优缺点,最后展望未来发展趋势及其研究方向。

横风下基于滚动GAPSO算法的列车速度曲线优化

针对普通环境下高速列车目标速度曲线优化算法不适用于横风环境的问题,提出一种横风环境下基于滚动GAPSO(遗传粒子群)算法的列车速度曲线优化方法。首先,考虑横风风速阻力作用改进列车动力学模型,并建立列车运行多目标优化模型;其次,基于GAPSO算法寻优巡航构建列车在起始阶段的最优目标速度曲线,引入滚动优化框架实时调整目标速度曲线,并在横风限速区按照改进快行策略运行;最后,在列车进站前采用GAPSO算法寻优惰行点生成目标速度曲线。仿真实验结果表明:GAPSO算法较GA算法和PSO算法具有搜索能力强、收敛速度快的优点;滚动GAPSO算法能在不同横风环境下实时生成优化后的目标速度曲线,并与改进快行策略和RH-PSO算法相比,具有较优的节能性和准时性。横风下基于滚动GAPSO算法的列车目标速度曲线优化可为横风环境下列车节能、准时运行提供一种可行的解决方案。

基于自动生成样本的优化Deeplabv3+网络速度建模方法

建立精确的速度模型对地震成像和解释十分重要,深度学习方法为建立精确的速度模型提供了新的途径,然而,目前可用于速度建模网络训练的样本非常有限。为此,提出了一种利用随机曲线模拟地下速度模型,自动生成大量样本用于深度学习训练的方法。该方法通过生成一组随机数,插值形成随机序列,利用三角函数将随机序列生成随机曲线来模拟地下界面,生成层状速度模型,在此基础上,通过添加断裂、速度异常体和地层倾角来模拟更复杂的速度模型;在速度预测网络构建方面,选取Deeplabv3+网络作为速度预测网络。通过增加卷积层的方法,优化了Deeplabv3+网络上采样后直接输出导致边界模糊的问题。将上述方法应用于模型数据和实际数据,测试了该方法在含噪声、不同子波频率和部分数据缺失情况下的稳定性。结果表明,该方法能够有效地应对噪声、不同子波频率和部分数据缺失的影响,具有可靠的泛化性和鲁棒性。

一种液压挖掘机最优能耗的轨迹规划方法

为了降低液压挖掘机的运动能量消耗,实现各关节的合理有效作业,提出了基于T型速度曲线的关节插值方法,以实现液压挖掘机最优能耗轨迹规划。该方法将各关节的速度设定为匀加速、匀速和匀减速的形式以保证液压挖掘机在作业过程中的平稳性,以关节角度、角速度和角加速度为约束条件,利用改进的自适应遗传算法优化求解各关节的匀加(减)速和匀速运动时间,获得了各关节最优运动曲线,实现了液压挖掘机最优能耗轨迹规划。对基于T型速度曲线的插值规划方法进行仿真实验,并在相同条件下与四次多项式插值结果进行了对比。结果表明,该方法规划的轨迹能耗低,避免了各关节产生不必要的运动,有效减少了摩擦损耗,使得挖掘机可平稳、低能耗地完成作业。

水闸运行对河流中氮污染物迁移转化与降解机制的影响

近年来,氮素超标严重影响了河流水环境质量,造成水质恶化与水体富营养化,已经成为我国河流的主要水污染问题。水闸升降引起的河流水动力条件变化会对河流中不同形态氮素的迁移转化产生影响,进而影响不同形态氮素的降解系数。以山西省丹河为研究对象,探究水闸运行下氮污染物的迁移转化与降解机制。研究成果表明,NH_(4)^(+)-N降解系数与河流流速相关性显著,线性回归方程为:K(NH_(4)^(+)-N)=5.894 v-1.753(R=0.867,p<0.001);NO_(3)^(-)-N、NO_(2)^(-)-N和TN的降解系数均与河流流速的相关性不显著。顺直河段开闸放水期间,NH_(4)^(+)-N、NO_(3)^(-)-N、NO_(2)^(-)-N和TN的降解系数比闸门关闭期间高出0.37 d^(-1)、0.43 d^(-1)、0.24 d^(-1)、0.72 d^(-1);弯曲河段开闸放水期间,NH_(4)^(+)-N的降解系数比闸门关闭期间减少0.4 d^(-1),NO_(3)^(-)-N、NO_(2)^(-)-N、TN的降解系数比闸门关闭期间高出0.67 d^(-1)、0.42 d^(-1)、0.87 d^(-1)。开闸放水和闸门关闭时,NH_(4)^(+)-N浓度在河流行进过程中表现为在顺直河段减小,弯曲河段增大;NO_(3)^(-)-N浓度和总无机氮浓度则在顺直和弯曲河段都不断减少;开闸放水较水闸关闭状态,河流在行进过程中总无机氮浓度下降更快,有利于无机氮的去除。研究成果有助于揭示水闸运行下河流的脱氮机理,可以通过优化水闸运行,提高河流氮污染物降解系数。

五轴混联机构时间最优速度规划及精准插补

为提高五轴混联机构对复杂曲面及其特征的加工质量,提出一种准确识别曲率点的时间最优速度规划及精准插补方法。首先,采用向心法生成路径节点参数,作密集化处理生成速度节点参数;其次,用B样条描述速度曲线,通过伪加加速度将三阶约束模型转变为线性模型;然后,以速度节点参数为分段点,构造各段路径的时间积分函数,采用自适应辛普森积分法求解;最后,将所得离散点信息输入到运动控制卡进行轨迹加工。实验结果表明:本方法可快速收敛到全局最优,降低曲率点速度并迅速回升其邻域速度;计算所得路径总时间仅有3.5μs的波动,与常规插补方法收敛后的精度一致,且收敛时间更短;位置和角度的最大插补误差分别为0.76×10^(-3) mm和0.9×10^(-3)°,小于编码器分辨率,符合加工需求,特别是极大曲率处相比一般方法降低95.37%。因此,在路径曲线基础上生成的速度节点参数具备更好的曲率识别性,通过构造各段路径的时间积分函数求解路径总时间具备更高的鲁棒性与效率。

基于Dijkstra算法的煤矿水灾时期最优逃生路径设计

煤矿水灾事故发生后,最棘手的问题就是如何能在最短的时间内实现安全逃生。本文通过在台东山煤矿矿工井下的实际测量,得出井下巷道的类型、坡度、风速、是否设置局部障碍物等对巷道通行难易程度影响的大小,还提出了一种新型水中逃生速度曲线模型,得出不同水位高度不同身高对巷道通行时间的影响大小,继而得出当量长度的计算公式。本文还提出了安全系数的概念,只能当巷道的安全系数值大于0.5时才具备逃生条件。然后提出了加入等高线数值考量的Dijkstra算法最优路径的求取方法,多个安全逃生出口的K则最优路径的优化,以及对K则最优路径提出了新的理解,进行了延伸。最后以台东山煤矿基础数据,以1.7 m平均身高为例,对最优逃生路径的求取进行了实验验证,对实际煤矿水灾时期的逃生具有重大的指导意义。