基于Adaline算法的高速磁浮列车谐波检测及抑制方法

[目的]为了减小高速磁浮谐波对牵引网产生的影响,保障高速磁浮列车的正常运行,需研究高速磁浮牵引供电系统中的谐波特性及其相应的谐波抑制方法。[方法]分析了高速磁浮牵引供电系统的构成,并对双三相半控12脉冲多重整流电路及其谐波进行了理论分析和仿真。根据Adaline神经网络算法原理和高速磁浮谐波特性,构建基于Adaline的高速磁浮谐波检测模型。采用谐波补偿控制策略,产生与检测出的谐波方向相反、大小相等的电流作为补偿信号,对系统畸变电流进行谐波抑制。[结果及结论]仿真结果表明:采用基于Adaline算法的谐波检测及抑制方法前,谐波畸变率为11.16%,而采用该方法后,各次谐波含量明显降低,谐波畸变率下降为1.41%。研究结果表明:所提谐波检测及抑制方法可以有效减少谐波畸变,提高牵引供电系统的稳定性和工作效率。

Adaptive Gain Tuning Rule for Nonlinear Sliding-mode Speed Control of Encoderless Three-phase Permanent Magnet Assisted Synchronous Motor

In this paper, an adaptive gain tuning rule is designed for the nonlinear sliding mode speed control(NSMSC) in order to enhance the dynamic performance and the robustness of the permanent magnet assisted synchronous reluctance motor(PMa-Syn RM) with considering the parameter uncertainties. A nonlinear sliding surface whose parameters are altering with time is designed at first. The proposed NSMSC can minimize the settling time without any overshoot via utilizing a low damping ratio at starting along with a high damping ratio as the output approaches the target set-point. In addition, it eliminates the problem of the singularity with the upper bound of an uncertain term that is hard to be measured practically as well as ensures a rapid convergence in finite time, through employing a simple adaptation law. Moreover, for enhancing the system efficiency throughout the constant torque region, the control system utilizes the maximum torque per ampere technique. The nonlinear sliding surface stability is assured via employing Lyapunov stability theory. Furthermore, a simple sliding mode estimator is employed for estimating the system uncertainties. The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed speed estimation and the NSMSC approach for a 1.1-k W PMa-Syn RM under different speed references, electrical and mechanical parameters disparities, and load disturbance conditions.

Experimental,Numerical,and Analytical Studies on the Bending of Mechanically Lined Pipe

Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

Speed Identification of Speed Sensorless Linear Induction Motor Based on MRAS

In the linear induction motor control system,the optical grating speed transducer is susceptible to strong magnetic field interference.What's more,it may reduce motor integration and raise device costs.Therefore a speed identification method to replace grating speed transducer is studied in this article.This speed identification method for linear induction motor mainly adopts Model Reference Adaptive Method(Abbreviated as MRAS)and Popov Hyperstability Theory.The research content of this paper can be divided into four parts.First,the mathematical model of the motor based on the model reference adaptive system structure is deduced.Second,the adaptive law of the estimated speed is solved by Popov hyper-stability theory,which ensures the stability of the system.Third,the simulation model of the linear induction motor speed identification control system based on model reference adaptation is built in the MATLAB environment.Finally,the simulation test and analysis are carried out.The simulation results show that the speed identification control system can track the actual speed of the linear induction motor well in the no-load operation and the load operation,and the stability of the system is guaranteed in the full speed range.

Revising the H_(2)^(16)O line-shape parameters around 1.1μm based on the speed-dependent Nelkin–Ghatak profile and the Hartmann–Tran profile

Accurate spectroscopic data for H_(2)^(16)O in the 1.1μm region are particularly important for the study of Earth's atmosphere.The pure water vapor molecular spectra were measured based on direct laser absorption spectroscopy using a narrow line-width external cavity diode laser combined with a high-precision Fabry-Pérot etalon.A total of 31 H_(2)^(16)O transitions were studied for the first time by using the speed-dependent Nelkin-Ghatak profile and the Hartmann-Tran profile.From an accurate line-shape analysis,we obtained the line intensities and the self-broadening coefficients,and they are compared with the available data reported in the HITRAN 2016 database and the HITRAN 2020 database.Finally,we obtained information on the influence of Dicke narrowing,as well as the correlations between Dicke narrowing and speed dependence,and of speed-dependent effects.

Attack-Resilient Distributed Cooperative Control of Virtually Coupled High-Speed Trains via Topology Reconfiguration

Dear Editor,This letter addresses the resilient distributed cooperative control problem of a virtually coupled train convoy under stochastic disturbances and cyber attacks.The main purpose is to achieve distributed coordination of virtually coupled high-speed trains with the prescribed inter-train distance and same cruise velocity.

Speed limit effect during lane change in a two-lane lattice model under V2X environment

Speed limit measures are ubiquitous due to the complexity of the road environment,which can be supplied with the help of vehicle to everything(V2X)communication technology.Therefore,the influence of speed limit on traffic system will be investigated to construct a two-lane lattice model accounting for the speed limit effect during the lane change process under V2X environment.Accordingly,the stability condition and the mKdV equation are closely associated with the speed limit effect through theory analysis.Moreover,the evolution of density and hysteresis loop is simulated to demonstrate the positive role of the speed limit effect on traffic stability in the cases of strong reaction intensity and high limited speed.

Effect of speed humps on instantaneous traffic emissions in a microscopic model with limited deceleration capacity

As a common transportation facility, speed humps can control the speed of vehicles on special road sections to reduce traffic risks. At the same time, they also cause instantaneous traffic emissions. Based on the classic instantaneous traffic emission model and the limited deceleration capacity microscopic traffic flow model with slow-to-start rules, this paper has investigated the impact of speed humps on traffic flow and the instantaneous emissions of vehicle pollutants in a single lane situation. The numerical simulation results have shown that speed humps have significant effects on traffic flow and traffic emissions. In a free-flow region, the increase of speed humps leads to the continuous rise of CO_(2), NO_(X) and PM emissions. Within some density ranges, one finds that these pollutant emissions can evolve into some higher values under some random seeds. Under other random seeds, they can evolve into some lower values. In a wide moving jam region, the emission values of these pollutants sometimes appear as continuous or intermittent phenomenon. Compared to the refined Na Sch model, the present model has lower instantaneous emissions such as CO_(2), NO_(X) and PM and higher volatile organic components(VOC) emissions. Compared to the limited deceleration capacity model without slow-to-start rules, the present model also has lower instantaneous emissions such as CO_(2), NO_(X) and PM and higher VOC emissions in a wide moving jam region. These results can also be confirmed or explained by the statistical values of vehicle velocity and acceleration.

Derivative Spectroscopy and its Application at Detecting the Weak Emission/Absorption Lines

The development of spectroscopic survey telescopes like Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),Apache Point Observatory Galactic Evolution Experiment and Sloan Digital Sky Survey has opened up unprecedented opportunities for stellar classification.Specific types of stars,such as early-type emission-line stars and those with stellar winds,can be distinguished by the profiles of their spectral lines.In this paper,we introduce a method based on derivative spectroscopy(DS)designed to detect signals within complex backgrounds and provide a preliminary estimation of curve profiles.This method exhibits a unique advantage in identifying weak signals and unusual spectral line profiles when compared to other popular line detection methods.We validated our approach using synthesis spectra,demonstrating that DS can detect emission signals three times fainter than Gaussian fitting.Furthermore,we applied our method to 579,680 co-added spectra from LAMOST Medium-Resolution Spectroscopic Survey,identifying 16,629 spectra with emission peaks around the Hαline from 10,963 stars.These spectra were classified into three distinct morphological groups,resulting in nine subclasses as follows.(1)Emission peak above the pseudo-continuum line(single peak,double peaks,emission peak situated within an absorption line,P Cygni profile,Inverse P Cygni profile);(2)Emission peak below the pseudo-continuum line(sharp emission peak,double absorption peaks,emission peak shifted to one side of the absorption line);(3)Emission peak between the pseudo-continuum line.

Complementary-Label Adversarial Domain Adaptation Fault Diagnosis Network under Time-Varying Rotational Speed and Weakly-Supervised Conditions

Recent research in cross-domain intelligence fault diagnosis of machinery still has some problems,such as relatively ideal speed conditions and sample conditions.In engineering practice,the rotational speed of the machine is often transient and time-varying,which makes the sample annotation increasingly expensive.Meanwhile,the number of samples collected from different health states is often unbalanced.To deal with the above challenges,a complementary-label(CL)adversarial domain adaptation fault diagnosis network(CLADAN)is proposed under time-varying rotational speed and weakly-supervised conditions.In the weakly supervised learning condition,machine prior information is used for sample annotation via cost-friendly complementary label learning.A diagnosticmodel learning strategywith discretized category probabilities is designed to avoidmulti-peak distribution of prediction results.In adversarial training process,we developed virtual adversarial regularization(VAR)strategy,which further enhances the robustness of the model by adding adversarial perturbations in the target domain.Comparative experiments on two case studies validated the superior performance of the proposed method.

Petrology of Spinel-Lherzolite Xenoliths from Mazéléand Others Northen Xenoliths Localities of Cameroon Volcanic Line: Exchange Reactions and Equilibrium State

The alkaline volcanism of the Cameroon Volcanic Line in its northern domain has raised many fresh enclaves of peridotites. The samples selected come from five (05) different localities (Liri, in the plateau of Kapsiki, Mazélé in the NE of Ngaoundéré, Tello and Ganguiré in the SE of Ngaoundéré and Likok, locality located in the west of Ngaoundé). The peridotite enclaves of the above localities show restricted mineralogical variation. Most are four-phase spinel-lherzolites, indicating that this is the main lithology that forms the lithospheric mantle below the shallow zone. No traces of garnet or primary plagioclase were detected, which strongly limits the depth range from which the rock fragments were sampled. The textures and the wide equilibrium temperatures (884˚C - 1115˚C) indicate also entrainment of lherzolite xenoliths from shallow depths within the lithosphere and the presence of mantle diapirism. The exchange reactions and equilibrium state established in this work make it possible to characterize the chemical composition of the upper mantle of each region and test the equilibrium state of the phases between them. Variations of major oxides and incompatible elemental concentrations in clinopyroxene indicate a primary control by partial melting. The absence of typical “metasomatic” minerals, low equilibration temperatures and enriched LREE patterns indicate that the upper mantle below septentrional crust of Cameroun underwent an event of cryptic metasomatic enrichment prior to partial melting. The distinctive chemical features, LREE enrichment, strong U, Ce and Pr, depletion relative to Ba, Nb, La, Pb, and T, fractionation of Zr and Hf and therefore ligh high Zr/Hf ratio, low La/Yb, Nb/La and Ti/Eu are all results of interaction of refractory peridotite residues with carbonatite melts.

Evaluation of red soil-bentonite mixtures for compacted clay liners

Compacted clay liners are an integral part of the waste landfills,which are provided to contain the leachate within the landfills and protect the surrounding environment.Generally,locally available natural soils are used for the construction of compacted clay liners if they satisfy the design criteria.However,not all soils in their natural state satisfy all the design criteria for the liner materials.Thus,there is a definite need to modify the locally available natural soils by blending with bentonite to meet the required design criteria for the liners.In view of this,the present study evaluates the suitability of an Indian red soil enhanced with bentonite as a liner material.To achieve this,a series of experiments were carried out using locally available red soil and bentonite.First,the suitability of the red soil was evaluated as a liner material.The experimental results showed that the red soil met all the selection criteria stipulated by the Environmental Protection Agencies(EPAs)for the liners except the hydraulic conductivity criterion.Therefore,the red soil was mixed with bentonite contents of 10%,20%and 30%,and the red soil-bentonite mixtures were evaluated for their suitability for liners in their compacted state.Further,as the liners in the arid and semi-arid regions are subjected to moisture variations due to seasonal moisture fluctuations and other factors,the red soil-bentonite mixtures were subjected to wetdry cycles,and their suitability was evaluated after wet-dry cycles.The experimental results revealed that all the red soil-bentonite mixtures met the stipulated EPA criteria for the liners in the as-compacted state.However,the red soil-bentonite mixtures with 20%and 30%bentonite contents only satisfied the hydraulic conductivity requirement even after wet-dry cycles.The experimental findings were supplemented with the microstructural insights captured through digital camera images,scanning electron microscopy(SEM),and mercury intrusion porosimetry(MIP)studies.

Relationships between Terrain Features and Forecasting Errors of Surface Wind Speeds in a Mesoscale Numerical Weather Prediction Model

Numerical weather prediction(NWP)models have always presented large forecasting errors of surface wind speeds over regions with complex terrain.In this study,surface wind forecasts from an operational NWP model,the SMS-WARR(Shanghai Meteorological Service-WRF ADAS Rapid Refresh System),are analyzed to quantitatively reveal the relationships between the forecasted surface wind speed errors and terrain features,with the intent of providing clues to better apply the NWP model to complex terrain regions.The terrain features are described by three parameters:the standard deviation of the model grid-scale orography,terrain height error of the model,and slope angle.The results show that the forecast bias has a unimodal distribution with a change in the standard deviation of orography.The minimum ME(the mean value of bias)is 1.2 m s^(-1) when the standard deviation is between 60 and 70 m.A positive correlation exists between bias and terrain height error,with the ME increasing by 10%−30%for every 200 m increase in terrain height error.The ME decreases by 65.6%when slope angle increases from(0.5°−1.5°)to larger than 3.5°for uphill winds but increases by 35.4%when the absolute value of slope angle increases from(0.5°−1.5°)to(2.5°−3.5°)for downhill winds.Several sensitivity experiments are carried out with a model output statistical(MOS)calibration model for surface wind speeds and ME(RMSE)has been reduced by 90%(30%)by introducing terrain parameters,demonstrating the value of this study.

ST-LaneNet: Lane Line Detection Method Based on Swin Transformer and LaneNet

The advancement of autonomous driving heavily relies on the ability to accurate lane lines detection.As deep learning and computer vision technologies evolve,a variety of deep learning-based methods for lane line detection have been proposed by researchers in the field.However,owing to the simple appearance of lane lines and the lack of distinctive features,it is easy for other objects with similar local appearances to interfere with the process of detecting lane lines.The precision of lane line detection is limited by the unpredictable quantity and diversity of lane lines.To address the aforementioned challenges,we propose a novel deep learning approach for lane line detection.This method leverages the Swin Transformer in conjunction with LaneNet(called ST-LaneNet).The experience results showed that the true positive detection rate can reach 97.53%for easy lanes and 96.83%for difficult lanes(such as scenes with severe occlusion and extreme lighting conditions),which can better accomplish the objective of detecting lane lines.In 1000 detection samples,the average detection accuracy can reach 97.83%,the average inference time per image can reach 17.8 ms,and the average number of frames per second can reach 64.8 Hz.The programming scripts and associated models for this project can be accessed openly at the following GitHub repository:https://github.com/Duane 711/Lane-line-detec tion-ST-LaneNet.

Characterization of the infectivity of an Indonesian Zika virus strain in mammalian cell lines

Objective:To characterize the infection patterns and growth characteristics of the Zika virus(ZIKV)strain JMB-185 from Indonesia in various mammalian cell lines.Methods:ZIKV was grown in human(A549,HEK293,HepG2,Huh7,Jurkat,and THP-1)and non-human mammalian(RAW264.7,Vero,and Vero76)cell lines.Viral replication kinetics were measured using plaque assay,while intra-and extracellular viral RNA concentrations were assessed using RT-PCR.Flow cytometry was used to quantify the infected cells and cell viability was measured using an MTT assay.The ability of ZIKV to infect cell lines was visualized using a fluorescence immunostaining assay.Results:This ZIKV strain preferentially infected the lung,kidney,and liver cell lines A549,HEK293,Huh7,Vero,and Vero76,but not the immune cells Jurkat,RAW264.7,and THP-1.By contrast,the ZIKV showed no sign of infection in HepG2 cells,while maintaining viral titer over 3 days post-infection,with no infection recorded in immunostaining,no increase in viral RNA,and no indication of cell deterioration.Conclusions:The Indonesian ZIKV strain has a similar infection profile as other strains,except for its poor infectivity on HepG2 cells.Information on the growth characteristics of Indonesia ZIKV will help expand our understanding of the biology of ZIKV which will be useful for various applications including antiviral discovery.

Warhead fragments motion trajectories tracking and spatio-temporal distribution reconstruction method based on high-speed stereo photography

High speed photography technique is potentially the most effective way to measure the motion parameter of warhead fragment benefiting from its advantages of high accuracy,high resolution and high efficiency.However,it faces challenge in dense objects tracking and 3D trajectories reconstruction due to the characteristics of small size and dense distribution of fragment swarm.To address these challenges,this work presents a warhead fragments motion trajectories tracking and spatio-temporal distribution reconstruction method based on high-speed stereo photography.Firstly,background difference algorithm is utilized to extract the center and area of each fragment in the image sequence.Subsequently,a multi-object tracking(MOT)algorithm using Kalman filtering and Hungarian optimal assignment is developed to realize real-time and robust trajectories tracking of fragment swarm.To reconstruct 3D motion trajectories,a global stereo trajectories matching strategy is presented,which takes advantages of epipolar constraint and continuity constraint to correctly retrieve stereo correspondence followed by 3D trajectories refinement using polynomial fitting.Finally,the simulation and experimental results demonstrate that the proposed method can accurately track the motion trajectories and reconstruct the spatio-temporal distribution of 1.0×10~3fragments in a field of view(FOV)of 3.2 m×2.5 m,and the accuracy of the velocity estimation can achieve 98.6%.

An Implementation of Multiscale Line Detection and Mathematical Morphology for Efficient and Precise Blood Vessel Segmentation in Fundus Images

Diagnosing various diseases such as glaucoma,age-related macular degeneration,cardiovascular conditions,and diabetic retinopathy involves segmenting retinal blood vessels.The task is particularly challenging when dealing with color fundus images due to issues like non-uniformillumination,low contrast,and variations in vessel appearance,especially in the presence of different pathologies.Furthermore,the speed of the retinal vessel segmentation system is of utmost importance.With the surge of now available big data,the speed of the algorithm becomes increasingly important,carrying almost equivalent weightage to the accuracy of the algorithm.To address these challenges,we present a novel approach for retinal vessel segmentation,leveraging efficient and robust techniques based on multiscale line detection and mathematical morphology.Our algorithm’s performance is evaluated on two publicly available datasets,namely the Digital Retinal Images for Vessel Extraction dataset(DRIVE)and the Structure Analysis of Retina(STARE)dataset.The experimental results demonstrate the effectiveness of our method,withmean accuracy values of 0.9467 forDRIVE and 0.9535 for STARE datasets,aswell as sensitivity values of 0.6952 forDRIVE and 0.6809 for STARE datasets.Notably,our algorithmexhibits competitive performance with state-of-the-art methods.Importantly,it operates at an average speed of 3.73 s per image for DRIVE and 3.75 s for STARE datasets.It is worth noting that these results were achieved using Matlab scripts containing multiple loops.This suggests that the processing time can be further reduced by replacing loops with vectorization.Thus the proposed algorithm can be deployed in real time applications.In summary,our proposed system strikes a fine balance between swift computation and accuracy that is on par with the best available methods in the field.

Characterization and Analysis of Inconel 718 Alloy Ground at Different Speeds

Inconel 718(IN718)alloy is widely applied to fabricate high temperature resistant or corrosion resistant parts due to its excellent mechanical performance.However,the machining of IN718 alloy is difficult as it may cause serious tool wear and poor surface quality(SQ)of the workpiece.In this work,grinding experiments on IN718 alloy at different speeds were conducted by using a CBN grinding wheel.The relationship between grinding speed,SQ and subsurface damage(SSD)was well studied.With increasing grinding speed,surface roughness decreased,and SQ was greatly improved.Meanwhile,the microhardness of the grinding surface declined as the grinding speed increased.The SSD depth was almost unchanged when the grinding speed was lower than 15 m/s,then it decreased with higher grinding speeds.It was attributed to the mechanical-thermal synergistic effect in the grinding process.The results indicated that increasing grinding speed can effectively improve the SQ and reduce the SSD of IN718 alloy.The conclusion in the work may also provide insight into processing other hard-to-machining materials.

On traceable iterated line graph and hamiltonian path index

Xiong and Liu[21]gave a characterization of the graphs G for which the n-iterated line graph L^(n)(G)is hamiltonian,for n≥2.In this paper,we study the existence of a hamiltonian path in L^(n)(G),and give a characterization of G for which L^(n)(G)has a hamiltonian path.As applications,we use this characterization to give several upper bounds on the hamiltonian path index of a graph.

Preheating-assisted solid-state friction stir repair of Al-Mg-Si alloy plate at different rotational speeds

Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five years.In this work,the microstructural evolution and mechanical performance of the Al-Mg-Si alloy plate repaired by the preheating-assisted AFSD process were investigated.To evaluate the tool rotation speed and substrate preheating for repair quality,the AFSD technique was used to additively repair 5 mm depth blind holes on 6061 aluminum alloy substrates.The results showed that preheat-assisted AFSD repair significantly improved joint bonding and joint strength compared to the control non-preheat substrate condition.Moreover,increasing rotation speed was also beneficial to improve the metallurgical bonding of the interface and avoid volume defects.Under preheating conditions,the UTS and elongation were positively correlated with rotation speed.Under the process parameters of preheated substrate and tool rotation speed of 1000 r/min,defect-free specimens could be obtained accompanied by tensile fracture occurring in the substrate rather than the repaired zone.The UTS and elongation reached the maximum values of 164.2MPa and 13.4%,which are equivalent to 99.4%and 140%of the heated substrate,respectively.