Complements to the Theory of Higher-Order Types of Asymptotic Variation for Differentiable Functions

The purpose of this paper is to add some complements to the general theory of higher-order types of asymptotic variation developed in two previous papers so as to complete our elementary (but not too much!) theory in view of applications to the theory of finite asymptotic expansions in the real domain, the asymptotic study of ordinary differential equations and the like. The main results concern: 1) a detailed study of the types of asymptotic variation of an infinite series so extending the results known for the sole power series;2) the type of asymptotic variation of a Wronskian completing the many already-published results on the asymptotic behaviors of Wronskians;3) a comparison between the two main standard approaches to the concept of “type of asymptotic variation”: via an asymptotic differential equation or an asymptotic functional equation;4) a discussion about the simple concept of logarithmic variation making explicit and completing the results which, in the literature, are hidden in a quite-complicated general theory.

Higher-order differential variational principle and differential equations of motion for mechanical systems in event space

In this paper we study the higher-order differential variational principle and differential equations of motion for mechanical systems in event space. Based on the higher-order d＇Alembert principle of the system, the higher-order velocity energy and the higher-order acceleration energy of the system in event space are defined, the higher-order d＇Alembert- Lagrange principle of the system in event space is established, and the parametric forms of Euler-Lagrange, Nielsen and Appell for this principle are given. Finally, the higher-order differential equations of motion for holonomic systems in event space are obtained.

A Cell Screening Algorithm Integrating Genetic and Numerical Differentiation

The consistency of the cell has a significant impact on battery capacity,endurance,overall performance,safety,and service life extension.However,it is challenging to identify cells with high consistency and no loss of battery energy.This paper presents a cell screening algorithm that integrates genetic and numerical differentiation techniques.Initially,a mathematical model for battery consistency is established,and a multi-step charging strategy is proposed to satisfy the demands of fast charging technology.Subsequently,the genetic algorithm simulates biological evolution to efficiently search for superior cell combinations within a short time while evaluating capacity,voltage consistency,and charge/discharge efficiency.Finally,through experimental validation and comparative analysis with similar algorithms,our proposed method demonstrates notable advantages in terms of both search efficiency and performance.

Typical adaptive neural control for hypersonic vehicle based on higher-order filters

A typical adaptive neural control methodology is used for the rigid body model of the hypersonic vehicle. The rigid body model is divided into the altitude subsystem and the velocity subsystem. The proportional integral differential(PID) controller is introduced to control the velocity track. The backstepping design is applied for constructing the controllers for the altitude subsystem.To avoid the explosion of differentiation from backstepping, the higher-order filter dynamic is used for replacing the virtual controller in the backstepping design steps. In the design procedure,the radial basis function(RBF) neural network is investigated to approximate the unknown nonlinear functions in the system dynamic of the hypersonic vehicle. The simulations show the effectiveness of the design method.

Differential correction method applied to measurement of the FAST reflector

The Five-hundred-meter Aperture Spherical radio Telescope （FAST） adopts an active deformable main reflector which is composed of 4450 triangular panels. During an observation, the illuminated area of the reflector is deformed into a 300-m diameter paraboloid and directed toward a source. To achieve accurate control of the reflector shape, positions of 2226 nodes distributed around the entire reflector must be measured with sufficient precision within a limited time, which is a challenging task because of the large scale. Measurement of the FAST reflector makes use of stations and node targets. However, in this case the effect of the atmosphere on measurement accuracy is a significant issue. This paper investigates a differen- tial correction method for total stations measurement of the FAST reflector. A multi-benchmark differential correction method, including a scheme for benchmark selection and weight assignment, is proposed. On- site evaluation experiments show there is an improvement of 70%-80% in measurement accuracy compared with the uncorrected measurement, verifying the effectiveness of the proposed method.

Novel differential unitary space-time modulation schemes for fast fading channels

Differential unitary space-time modulation （DUSTM）, which obtains full transmit diversity in slowly fiat-fading channels without channel state iufonnation, has generated significant interests recently. To combat frequency-selective fading, DUSTM has been applied to each subcarrier of an OFDM system and DUSTM-OFDM system was proposed. Both DUSTM and DUSTM-OFDM, however, are designed for slowly fading channels and suffer performance deterioration in fast fading channels. In this paper, two novel differential unitary space-time modulation schemes are proposed for fast fading channels. For fast fiat-fading channels, a subatrix interleaved DUSTM （SMI-DUSTM） scheme is proposed, in which matrix-segmentation and sub-matrix based interleaving are introduced into DUSTM system. For fast frequency-selective fading channels, a differential unitary space-frequency modulation （DUSFM） scheme is proposed, in which existing unitary space-time codes are employed across transmit antennas and OFDM subcarriers simultaneouslv and differential modulation is performed between two adjacent OFDM blocks. Compared with DUSTM and DUSTM-OFDM schemes, SMI-DUSTM and DUSFM-OFDM are more robust to fast channel fading with low decoding complexity, which is demonstrated by performance analysis and simulation resuits.

Modeling Fast Diffusion Processes in Time Integration of Stiff Stochastic Differential Equations

Numerical algorithms for stiff stochastic differential equations are developed using lin-ear approximations of the fast diffusion processes,under the assumption of decoupling between fast and slow processes.Three numerical schemes are proposed,all of which are based on the linearized formulation albeit with different degrees of approximation.The schemes are of comparable complexity to the classical explicit Euler-Maruyama scheme but can achieve better accuracy at larger time steps in stiff systems.Convergence analysis is conducted for one of the schemes,that shows it to have a strong convergence order of 1/2 and a weak convergence order of 1.Approximations arriving at the other two schemes are discussed.Numerical experiments are carried out to examine the convergence of the schemes proposed on model problems.

Comparing the Effect of Different Concentration of Sulfuric Acid Differentiation Solution on Acid Fast Dyeing

Objective: In the acid-fast staining experiment of pathological tissues, sulfuric acid and hydrochloric acid were used to evaluate the staining results, so as to get the best staining method. Methods: Using sulfuric acid differentiation solution and hydrochloric acid differentiation solution, the paraffin blocks of pathological tissues known to contain Mycobacterium tuberculosis were compared to evaluate the staining effect. Results: When 0.5% hydrochloric acid differentiation solution is used and the differentiation time is 6 s, the dyeing effect is better than that of sulfuric acid differentiation solution.

基于电子鼻技术结合网络药理学分析半夏不同炮制品的气味差异标志物

目的借助HeraclesⅡ超快速气相电子鼻获取半夏不同炮制品的气味指纹图谱信息,并结合网络药理学分析半夏不同炮制品之间的气味差异标志物。方法使用HeraclesⅡ超快速气相电子鼻获取半夏不同炮制品的气相色谱图,利用多元分析方法,得到半夏不同炮制品的气味差异标志物,结合网络药理学分析,得到差异成分的靶点和通路,从而预测半夏不同炮制品潜在的气味差异标志物。结果半夏不同炮制品共鉴定出21个与气味相关的化学成分,其中甲基丁香酚、二乙基酮等5个成分是半夏不同炮制品的气味差异标志物,经网络药理学分析,这些成分具有止咳、抗炎等作用。结论所建立的半夏及其炮制品气味指纹图谱专属性强,筛选出5种可作为半夏不同炮制品的潜在气味差异标志物的化学成分,可为中药炮制机制及工艺研究提供新思路和适用方法。

基于FPDE-SIFT的声呐干涉图像配准方法

图像配准是声呐进行高精度干涉测量的保障,该文针对水下目标的声呐图像配准,提出了一种基于4阶偏微分方程尺度不变特征变换的声呐干涉图像配准方法。该方法聚焦声呐图像配准的难点,首先基于4阶偏微分方程构建尺度空间,在保持图像细节的前提下滤除噪声,提高特征提取的准确度;对于残余噪声造成的特征点误检,借助特征点的相位一致性信息加以筛选,精简特征点样本集;最后对特征点匹配策略进行优化,提出改进的快速样本一致性匹配策略剔除特征点的误匹配。算法增加了匹配点对的数量,提高了匹配点对的准确度,实现了声呐干涉图像的精确配准。水池实验和外场试验表明,该文所提出的算法相较现有算法对声呐图像有着更好的适用性,配准后的均方根误差与留一法均方根均小于1像素,达到了亚像素配准精度。

基于NESO-LFDC的四旋翼无人机滑模姿态控制

针对四旋翼无人机姿态控制中存在空气动力学特性复杂,易受干扰的特性,提出一种基于非线性扩张状态观测器(nonlinear extended state observer,NESO)和低频干扰补偿器(low-frequency disturbance compensator,LFDC)的非奇异快速终端滑模控制方法。该方法内环设计了NESO和LFDC结合,以获得干扰补偿值并补偿总干扰的低频分量。在外环设计了跟踪微分器和可变切换增益的非奇异快速终端滑模控制器,用于补偿虚拟干扰估计值的误差和总干扰的高频分量。仿真结果表明,该控制方法可以更好地估计总干扰的低频和高频分量,减少虚拟干扰估计值的误差对四旋翼无人机姿态控制的影响,并提升响应速度。

基于群体划分的冠状病毒群体免疫优化算法

针对冠状病毒群体免疫优化(CHIO)算法收敛速度慢、求解精度低的问题,提出一种基于群体划分的冠状病毒群体免疫优化(SD-CHIO)算法.基于适应度均匀原则将初始群体划分为两部分,即全局寻优个体与局部寻优个体.对于全局寻优个体,在其位置更新中加入差分变异与漫反射变异策略,分别用来增强全局寻优个体之间的交流与群体多样性,从而提高算法的全局搜索能力.对于局部寻优个体,在其位置更新中引入一种自适应快速收敛策略:基于增量法进行精英预测,并加入一种自适应收敛系数使局部寻优个体能快速收敛至精英解,以提升算法的局部搜索能力.数值实验表明:SD-CHIO能够有效提高原算法的收敛速度与精度,并表现出明显优于其他元启发式算法的全局与局部搜索能力以及一定的工程价值.

极端快速条件下液体电导率实时测量技术

基于对称差分原理,发展了一套用于极端快速条件下液体介质电导率的实时原位测量技术,主要解决了传统测量方法在极端快速条件下测量液体电导率时液体介质易电解,以及快速冲击过程中液体介质的冲击极化对电压信号测量带来困难等问题。该实时测量技术在样品测试过程中两端电压不超过电极电势,且测量时间仅为数微秒,从而保证了液体介质不受强电场影响发生电解,通过对样品中两电极分别测量的电压信号进行差分,有效消除由液体介质受到快速冲击时产生的极化干扰,从而提升在极端快速条件下的测量精度和可靠性。以对去离子水进行快速冲击测试实验为例,结果显示该测量技术能在纳秒时间尺度内准确反映导电性变化历史,展现出广泛的科研和工程应用潜力。

船舶供电系统失电快速恢复方法

为能够在船舶供电系统发生失电故障时,迅速、准确地定位故障点,并有效恢复供电,本研究基于网络拓扑有向遍历技术,设计了一种船舶供电系统失电快速恢复方法。在船舶供电系统失电故障指示器发出失电预警后,构建供电系统网络拓扑有向图,有向图的每个顶点和边代表的线路节点。利用深度优先搜索遍历算法,逐一搜索故障指示器预警范围,定位失电故障位置;针对失电故障位置,启动船舶供电系统失电快速恢复模型,构建负载恢复供电速度最大化、开关动作次数最小化的失电恢复目标函数,利用差分进化算法求解满足目标函数条件的备用发电机组启停、负载开关切换方案,实现失电快速恢复。实验数据证明:此方法可在1.05 s范围内快速实现失电恢复。

针对船舶排放污染物分布监测的地基快速IDOAS技术研究

针对我国船舶排放污染物防治的迫切需求,2021年中国出台了《船舶大气污染物排放监测通用要求》,对船舶大气污染物排放的监测精度提出了更高的要求。现阶段,我国内河中的多数船只都以低端柴油发动机作为主要动力来源,并在未来的很长一段时间内,柴油机都将继续作为船舶的主要动力装置使用。船舶使用的油品通常杂质多、品质差,加上柴油发动机大多较为老旧,老化的柴油发动机工作时会排放大量硫氧化合物、氮氧化合物等大气污染物,对大气环境造成严重危害,因此对于船舶大气污染物排放的监测研究尤为重要。基于成像差分吸收光谱技术研制了一套地基快速成像差分吸收光谱系统,能够实现对污染物空间分布的“拍照”式探测。系统时间分辨率可达秒级,系统视场角为6°×6°。选择无云条件下的正午天顶太阳散射光光谱作为参考光谱并使用QDOAS软件对获得的数据进行反演。根据系统中摄像头采集到的观测区域图像信息,将污染气体浓度信息与空间信息进行匹配,能够获得船舶大气污染物的空间二维分布情况。为验证系统的可靠性,2022年9月,在铜陵以发电厂烟羽中的SO_(2)为目标进行了比对验证实验,并与推扫地基成像差分吸收光谱仪器的结果进行了相关性分析,SO_(2)斜柱浓度的相关性为0.935。2022年12月,采用地基快速成像差分吸收光谱系统对长江船舶污染物排放进行了观测,获取了时间分辨率为5 s的SO_(2)连续空间二维分布信息,通过与摄像头获取的图像信息匹配,能够将高浓度排放追溯到具体船只。该研究为船舶等快速移动污染源的监测提供了有效的实时监测手段,为船舶排放的治理提供了可靠的数据支撑。

两种分化试剂对麻风杆菌的染色效果比较

目的比较20%硫酸和酸性酒精作为分化试剂对麻风杆菌的染色效果,为麻风患者选取更好的抗酸染色分化试剂。方法选择61例确诊为麻风阳性患者的皮损组织切片,在分化时间为0.5、1.0、1.5 min下,分别采用20%的硫酸和成品试剂盒内酸性酒精分化,观察并比较两种方法下连续切片菌落量以及汗腺附近红色异染颗粒的变化。结果在分化时间0.5、1.0、1.5 min下,同一患者蜡块的连续切片中,20%硫酸均比成品试剂盒内酸性酒精染出更多的菌落(P值分别为0.038、0.012、0.017),并更容易染出汗腺异染小颗粒(均P<0.001)。结论在麻风杆菌染色检测中,使用20%硫酸分化比成品试剂盒内酸性酒精分化的菌落量表达效果更显著。

多目标下航天产品生产车间柔性资源配置与调度集成优化

航天产品的生产具有多品种、小批量特点,根据生产计划进行柔性资源配置与调度,对生产效率和响应能力都有重要影响。考虑了生产资源投入量可变、生产中存在准备加工运输等多种时间、生产资源性能差异等情况,本文以最小化超期交付天数、生产成本和总投入资源数量为目标,进行了柔性资源配置与调度集成优化问题的研究。首先,本文对研究问题进行了界定和详细描述,建立了多目标规划模型。其次,鉴于该问题的NP-hard特点,设计了基于Pareto优化的改进多目标差分进化算法,通过启发式染色体生成策略得到高质量的初始解集,结合快速非支配排序方法对个体进行排序,利用差分策略进行迭代优化,最终获得满意的解集。最后,通过算例分析将本文算法与两种常用算法进行了对比分析,验证了算法的有效性,并得出:当任务量多生产资源不足时,增加资源数量可以减少超期时间和生产成本;但当任务量少生产资源充足时,即使投入更多资源,也不会使得超期时间和生产成本进一步减少,还可能会带来资源浪费。

Differential Quadrature Method for Bending Problem of Plates with Transverse Shear Effects

A differential quadrature (DQ) method for orthotropic plates was proposed based on Reddy' s theory of plates with the effects of the higher-order transverse shear deformations. Wang-Bert's DQ approach was also further extended to handle the boundary conditions of plates. The computational convergence was studied, and the numerical results were obtained for different grid spacings and compared with the existing results. The results show that the DQ method is fairly reliable and effective.

Fourth-Order Splitting Methods for Time-Dependant Differential Equations

This study was suggested by previous work on the simulation of evolution equations with scale-dependent processes,e.g.,wave-propagation or heat-transfer,that are modeled by wave equations or heat equations.Here,we study both parabolic and hyperbolic equations.We focus on ADI (alternating direction implicit) methods and LOD (locally one-dimensional) methods,which are standard splitting methods of lower order,e.g.second-order.Our aim is to develop higher-order ADI methods,which are performed by Richardson extrapolation,Crank-Nicolson methods and higher-order LOD methods,based on locally higher-order methods.We discuss the new theoretical results of the stability and consistency of the ADI methods.The main idea is to apply a higher- order time discretization and combine it with the ADI methods.We also discuss the dis- cretization and splitting methods for first-order and second-order evolution equations. The stability analysis is given for the ADI method for first-order time derivatives and for the LOD (locally one-dimensional) methods for second-order time derivatives.The higher-order methods are unconditionally stable.Some numerical experiments verify our results.

Fast-transient techniques for high-frequency DC–DC converters

A 30 MHz voltage-mode controlled buck converter with fast transient responses is presented.An improved differential difference amplifier(DDA)-based Type-III compensator is proposed to reduce the settling times of the converter during load transients,and to achieve near-optimal transient responses with simple PWM control only.Moreover,a hybrid scheme using a digital linear regulator with automatic transient detection and seamless loop transition is proposed to further improve the transient responses.By monitoring the output voltage of the compensator instead of the output voltage of the converter,the proposed hybrid scheme can reduce undershoot and overshoot effectively with good noise immunity and without interrupting the PWM loop.The converter was fabricated in a 0.13μm standard CMOS process using 3.3 V devices.With an input voltage of 3.3 V,the measured peak efficiencies at the output voltages of 2.4,1.8,and 1.2 V are 90.7%,88%,and 83.6%,respectively.With a load step of 1.25 A and rise and fall times of 2 ns,the measured 1%settling times were 220 and 230 ns,with undershoot and overshoot with PWM control of 72 and 76 mV,respectively.They were further reduced to 36 and 38 mV by using the proposed hybrid scheme,and 1%settling times were also reduced to 125 ns.