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Influence of Vertical Irregularity on the Seismic Behavior of Base Isolated RC Structures with Lead Rubber Bearings under Pulse-Like Earthquakes
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作者 Ali Mahamied Amjad AYasin +2 位作者 Yazan Alzubi Jamal Al Adwan Issa Mahamied 《Structural Durability & Health Monitoring》 EI 2023年第6期501-519,共19页
Nowadays,an extensive number of studies related to the performance of base isolation systems implemented in regular reinforced concrete structures subjected to various types of earthquakes can be found in the literatu... Nowadays,an extensive number of studies related to the performance of base isolation systems implemented in regular reinforced concrete structures subjected to various types of earthquakes can be found in the literature.On the other hand,investigations regarding the irregular base-isolated reinforced concrete structures’performance when subjected to pulse-like earthquakes are very scarce.The severity of pulse-like earthquakes emerges from their ability to destabilize the base-isolated structure by remarkably increasing the displacement demands.Thus,this study is intended to investigate the effects of pulse-like earthquake characteristics on the behavior of low-rise irregular base-isolated reinforced concrete structures.Within the study scope,investigations related to the impact of the pulse-like earthquake characteristics,irregularity type,and isolator properties will be conducted.To do so,different values of damping ratios of the base isolation system were selected to investigate the efficiency of the lead rubber-bearing isolator.In general,the outcomes of the study have shown the significance of vertical irregularity on the performance of base-isolated structures and the considerable effect of pulse-like ground motions on the buildings’behavior. 展开更多
关键词 Reinforced concrete low-rise structure vertical irregularity the influence of pulse-like earthquake characteristics lead rubber bearing isolators nonlinear response history analysis
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Irregular initial solidification by mold thermal monitoring in the continuous casting of steels:A review
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作者 Qiuping Li Guanghua Wen +3 位作者 Fuhang Chen Ping Tang Zibing Hou Xinyun Mo 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第5期1003-1015,共13页
Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the ... Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed. 展开更多
关键词 irregular initial solidification mold thermal monitoring continuous casting mold slag THERMOCOUPLE
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Dynamic Constraint-Driven Event-Triggered Control of Strict-Feedback Systems Without Max/Min Values on Irregular Constraints
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作者 Zhuwu Shao Yujuan Wang +1 位作者 Zeqiang Li Yongduan Song 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第3期569-580,共12页
This work proposes an event-triggered adaptive control approach for a class of uncertain nonlinear systems under irregular constraints.Unlike the constraints considered in most existing papers,here the external irregu... This work proposes an event-triggered adaptive control approach for a class of uncertain nonlinear systems under irregular constraints.Unlike the constraints considered in most existing papers,here the external irregular constraints are considered and a constraints switching mechanism(CSM)is introduced to circumvent the difficulties arising from irregular output constraints.Based on the CSM,a new class of generalized barrier functions are constructed,which allows the control results to be independent of the maximum and minimum values(MMVs)of constraints and thus extends the existing results.Finally,we proposed a novel dynamic constraint-driven event-triggered strategy(DCDETS),under which the stress on signal transmission is reduced greatly and no constraints are violated by making a dynamic trade-off among system state,external constraints,and inter-execution intervals.It is proved that the system output is driven to close to the reference trajectory and the semi-global stability is guaranteed under the proposed control scheme,regardless of the external irregular output constraints.Simulation also verifies the effectiveness and benefits of the proposed method. 展开更多
关键词 Adaptive control dynamic constraint-driven event-triggered control irregular output constraints nonlinear strict-feed-back systems
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Performance and Complexity Trade-Off between Short-Length Regular and Irregular LDPC
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作者 Ziyuan Peng Ruizhe Yang 《Journal of Computer and Communications》 2024年第9期208-215,共8页
In this paper, both the high-complexity near-ML list decoding and the low-complexity belief propagation decoding are tested for some well-known regular and irregular LDPC codes. The complexity and performance trade-of... In this paper, both the high-complexity near-ML list decoding and the low-complexity belief propagation decoding are tested for some well-known regular and irregular LDPC codes. The complexity and performance trade-off is shown clearly and demonstrated with the paradigm of hybrid decoding. For regular LDPC code, the SNR-threshold performance and error-floor performance could be improved to the optimal level of ML decoding if the decoding complexity is progressively increased, usually corresponding to the near-ML decoding with progressively increased size of list. For irregular LDPC code, the SNR-threshold performance and error-floor performance could only be improved to a bottle-neck even with unlimited decoding complexity. However, with the technique of CRC-aided hybrid decoding, the ML performance could be greatly improved and approached with reasonable complexity thanks to the improved code-weight distribution from the concatenation of CRC and irregular LDPC code. Finally, CRC-aided 5GNR-LDPC code is evaluated and the capacity-approaching capability is shown. 展开更多
关键词 Regular LDPC irregular LDPC Near-ML Decoding List Decoding Belief Propagation Algorithm Sum-Product Algorithm CRC-Aided Hybrid Decoding
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Effect of temperature difference load of 32 m simply supported box beam bridge on track vertical irregularity 被引量:5
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作者 Kaize Xie Jun Xing +3 位作者 Li Wang Chunxiang Tian Rong Chen Ping Wang 《Journal of Modern Transportation》 2015年第4期262-271,共10页
In order to study the effect of temperature difference load (TDL) along the vertical direction of a simply supported beam bridge section on the vertical irregularity, a rail-bridge-piers calculation model was establ... In order to study the effect of temperature difference load (TDL) along the vertical direction of a simply supported beam bridge section on the vertical irregularity, a rail-bridge-piers calculation model was established. Taking 32 m simply supported box beam bridge which is widely used in the construction of pas- senger dedicated line in China as an example, influences of the temperature variation between the bottom and top of the bridge, temperature curve index, type of temperature gradient, and beam height on track vertical irregularity were analyzed with the model. The results show that TDL has more effects on long wave track irregularity than on short one, and the wavelength mainly affected is approxi- mately equal to the beam span. The amplitude of irregu- larity caused by TDL is largely affected by the temperature variation, temperature curve index, and type of temperature gradient, so it is necessary to monitor the temperaturedistribution of bridges in different regions to provide accurate calculation parameters. In order to avoid the irregularity exceeding the limit values, the height of 32, 48, and 64 m simply supported box beam bridges must not be less than 2.15, 3.2, and 4.05 m, respectively. 展开更多
关键词 Simply supported beam bridge Temperaturegradient Vertical irregularity - Beam height
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Subway Embedded Track Geometric Irregularity Safety Limits 被引量:3
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作者 Yuxiang Zhang Jian Han +1 位作者 Huilai Song Yu Liu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2021年第5期322-331,共10页
A coupling dynamic model of a subway train and an embedded track is established to study the safety limits of track irregularities.The simulated vehicle system was a 74-degrees of freedom multi-rigid body model,and th... A coupling dynamic model of a subway train and an embedded track is established to study the safety limits of track irregularities.The simulated vehicle system was a 74-degrees of freedom multi-rigid body model,and the rail was a Timoshenko beam.The slab was a three-dimensional solid finite element model.The sensitive wavelength irregularity was first studied,and then the safety limit of the sensitive wavelength was analyzed.The wheel-rail lateral force exhibited a substantial effect on the track alignment and gauge irregularity safety limit.The wheel-rail vertical force and the rate of wheel load reduction significantly affected the height and cross-level irregularity safety limit.The results demonstrate that the safety limits of the alignment,gauge,height,and cross-level embedded track geometric irregularity are 5.3 mm,[−10.5,8]mm,5.6 mm,and 6 mm,respectively. 展开更多
关键词 Embedded track irregularity Sensitive wavelength Safety limit
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Robust Spectral Estimation of Track Irregularity 被引量:2
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作者 傅文娟 陈春俊 《Journal of Southwest Jiaotong University(English Edition)》 2005年第1期44-48,共5页
Because the existing spectral estimation methods for railway track irregularity analysis are very sensitive to outliers, a robust spectral estimation method is presented to process track irregularity signals. The prop... Because the existing spectral estimation methods for railway track irregularity analysis are very sensitive to outliers, a robust spectral estimation method is presented to process track irregularity signals. The proposed robust method is verified using 100 groups of clean/contaminated data reflecting he vertical profile irregularity taken from Bejing-Guangzhou railway with a sampling frequency of 33 data every ~10 m, and compared with the Auto Regressive (AR) model. The experimental results show that the proposed robust estimation is resistible to noise and insensitive to outliers, and is superior to the AR model in terms of efficiency, stability and reliability. 展开更多
关键词 ROBUSTNESS Robust spectral estimation Railway track spectra Railway track irregularity
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Railway subgrade thermal-hydro-mechanical behavior and track irregularity under the sunny-shady slopes effect in seasonal frozen regions 被引量:3
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作者 REN Juan-juan ZHANG Kai-yao +4 位作者 ZHENG Jian-long WEI Hui ZHANG Yi-chi DU Wei YE Wen-long 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第11期3793-3810,共18页
The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static... The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static irregularity in the slab track.Based on the hydraulics theory,a thermal-hydro-mechanical(THM)coupled model of frozen soil is established and verified.We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track SystemⅢslab tracks under uneven frost heaving deformation.The results show that,because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation,which is the key factor causing uneven frost heaving of subgrade.Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface,leading to differences in the deformation of the slab track structure:Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line,and these become consistent in north-south directions.Therefore,when selecting railway lines in seasonal frozen areas,the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades. 展开更多
关键词 frost heaving thermal-hydro-mechanical coupling sunny-shady slopes effect track irregularity
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The effect of track alignment irregularity on wheel-rail contact geometry relationship in a turnout zone 被引量:1
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作者 Li WANG Ping WANG +1 位作者 Shunxi QUAN Rong CHEN 《Journal of Modern Transportation》 2012年第3期148-152,共5页
The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wh... The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wheel-rail geometry relationship with the trace line method. The profile of the key rail sections was matched by cubic spline curve, and the shape interpolation was realized in non-controlling sections. The results show that the roll angles at each typical section increases gradually with the enlargement of track alignment irregularity. When the flange contact occurs, the roll angle increases dramatically. Proper track alignment irregularity towards the switch rail improves the structure irregularity of the turnout. 展开更多
关键词 track alignment irregularity wheel-rail geometry relationship TURNOUT roll angle
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Characterizing neural activities evoked by manual acupuncture through spiking irregularity measures
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作者 薛明 王江 +3 位作者 邓斌 魏熙乐 于海涛 陈颖源 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第9期662-670,共9页
The neural system characterizes information in external stimulations by different spiking patterns. In order to examine how neural spiking patterns are related to acupuncture manipulations, experiments are designed in... The neural system characterizes information in external stimulations by different spiking patterns. In order to examine how neural spiking patterns are related to acupuncture manipulations, experiments are designed in such a way that different types of manual acupuncture (MA) manipulations are taken at the 'Zusanli' point of experimental rats, and the induced electrical signals in the spinal dorsal root ganglion are detected and recorded. The interspike interval (ISI) statistical histogram is fitted by the gamma distribution, which has two parameters: one is the time-dependent firing rate and the other is a shape parameter characterizing the spiking irregularities. The shape parameter is the measure of spiking irregularities and can be used to identify the type of MA manipulations. The coefficient of variation is mostly used to measure the spike time irregularity, but it overestimates the irregularity in the case of pronounced firing rate changes. However, experiments show that each acupuncture manipulation will lead to changes in the firing rate. So we combine four relatively rate- independent measures to study the irregularity of spike trains evoked by different types of MA manipulations. Results suggest that the MA manipulations possess unique spiking statistics and characteristics and can be distinguished according to the spiking irregularity measures. These studies have offered new insights into the coding processes and information transfer of acupuncture. 展开更多
关键词 ACUPUNCTURE interspike interval gamma distribution spiking irregularity measure
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Effect of irregularity on the propagation of torsional surface waves in an initially stressed anisotropic poro-elastic layer
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作者 S.GUPTA A.CHATTOPADHYAY D.K.MAJHI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2010年第4期481-492,共12页
The paper studies the propagation of torsional surface waves in an initially stressed anisotropic poro-elastic layer over a semi-infinite heterogeneous half space with linearly varying rigidity and density due to irre... The paper studies the propagation of torsional surface waves in an initially stressed anisotropic poro-elastic layer over a semi-infinite heterogeneous half space with linearly varying rigidity and density due to irregularity at the interface. The irregularity is taken in the half space in the form of a rectangle. It is observed that torsional surface waves propagate in this assumed medium. In the absence of the irregularity, the velocity equation of the torsional surface wave is also obtained. For a layer over a homogeneous half space, the velocity of torsional surface waves coincides with that of the Love waves. 展开更多
关键词 irregularity torsional surface waves ANISOTROPIC initial stress
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Propagation of Torsional Surface Waves under the Effect of Irregularity and Initial Stress
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作者 Shishir Gupta Dinesh K. Majhi +1 位作者 Sumit K. Vishwakarma Santimoy Kundu 《Applied Mathematics》 2011年第12期1453-1461,共9页
The present paper has been framed to study the influence of irregularity, initial stress and porosity on the propagation of torsional surface waves in an initially stressed anisotropic poro-elastic layer over a semi-i... The present paper has been framed to study the influence of irregularity, initial stress and porosity on the propagation of torsional surface waves in an initially stressed anisotropic poro-elastic layer over a semi-infinite heterogeneous half space with linearly varying rigidity and density due to irregularity at the interface. The irregularity has been taken in the half-space in the form of a parabola. It is observed that torsional sur- face waves propagate in this assumed medium. In the absence of irregularity the velocity of torsional surface wave has been obtained. Further, it has been seen that for a layer over a homogeneous half space, the velo- city of torsional surface waves coincides with that of Love waves. 展开更多
关键词 irregularity Torsional Surface WAVES ANISOTROPIC INITIAL STRESS
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Influence of Track Irregularity on Longitudinal Vibration of Wheelset and Correlation Performance
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作者 马卫华 罗世辉 宋荣荣 《Journal of Southwest Jiaotong University(English Edition)》 2006年第3期238-251,共14页
Longitudinal vibration of wheelset with respect to bogie frame often exists with a high acceleration magnitude and relative high frequency. First, a simplified model with a single wheelset moving at a constant speed o... Longitudinal vibration of wheelset with respect to bogie frame often exists with a high acceleration magnitude and relative high frequency. First, a simplified model with a single wheelset moving at a constant speed on a tangential track with irregularity is used to investigate the longitudinal vibration dynamics. Computional results indicate that the longitudinal vibration frequency of the wheelset is most sensitive to the primary longitudinal stiffness and the mass of the wheelset. As to the locomotive model, the longitudinal vibration is concerned with cross-level irregularity and vertical profile irregularity. Meanwhile, a method to estimate the resonance speed is presented. Finally, a possible solution is brought forward to extend wheel-rail service life by eliminating longitudinal vibration of the wheelset. The solution is simply to arrang the primary vertical damper with a forward angle, so that its damping component can be applied to longimdinal direction. 展开更多
关键词 Track irregularity ACCELERATION Longitudinal vibration DYNAMICS
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Strength and deformation characteristics of irregular columnar jointed rock mass: A combined experimental and theoretical study 被引量:2
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作者 Xiangcheng Que Zhende Zhu +2 位作者 Yanxin He Zihao Niu Haonan Huang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第2期429-441,共13页
The irregularity of jointed network poses a challenge to the determination of field mechanical param-eters of columnar jointed rock mass(CJRM),and a reasonable prediction of deformation and strength characteristics of... The irregularity of jointed network poses a challenge to the determination of field mechanical param-eters of columnar jointed rock mass(CJRM),and a reasonable prediction of deformation and strength characteristics of CJRM is important for engineering construction.The Voronoi diagram and three-dimensional printing technology were used to make an irregular columnar jointed mold,and the irregular CJRM(ICJRM)specimens with different dip directions and dip angles were prepared.Uniaxial compression tests were performed,and the anisotropic strength and deformation characteristics of ICJRM were described.The failure modes and mechanisms were revealed in accordance with the final appearances of the ICJRM specimens.Based on the model test results,the empirical correlations for determining the field deformation and strength parameters of CJRM were derived using the dip angle and modified joint factor.The proposed empirical equations were used in the Baihetan Project,and the calculated mechanical parameters were compared with the field test results and those obtained from the tunneling quality index method.Results showed that the deformation parameters determined by the two proposed methods are all consistent with the field test results,and these two methods can also estimate the strength parameters effectively. 展开更多
关键词 irregular columnar jointed rock mass (ICJRM) Physical model test Anisotropic characteristic Empirical relations Dip angle Modified joint factor
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Broadband underwater target echo detection based on signal spectral irregularity feature
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作者 Chen Yunfei Li Sheng +2 位作者 Jia Bing Wang Zhenshan Li Guijuan 《Journal of Southeast University(English Edition)》 EI CAS 2018年第2期147-155,共9页
For the detection of underwater target echo under strong interferences,the modulation feature of direct echo signal and reverberation spectrum are characterized by the signal spectral irregularity feature,and the rela... For the detection of underwater target echo under strong interferences,the modulation feature of direct echo signal and reverberation spectrum are characterized by the signal spectral irregularity feature,and the relationship between signal spectral irregularity and target physical properties is theoretically formed.A novel method of broadband underwater target echo detection under reverberation based on the signal spectral irregularity characteristics is proposed.The proposed method has the capability of discriminating between the direct target echo signal from reverberation.Simulation results of complex underwater target broadband acoustic scattering show that the echo can be detected even with the signal to reverberation ratio(SRR)below-10 dB by the proposed method based on the spectral irregularity(SI)feature.The corresponding sea experimental results also show that echo can be detected when the SRR is below 0 dB.The effectiveness and correctness of the proposed method are verified both in simulated data and in real data in sea experiment. 展开更多
关键词 ECHO REVERBERATION signal spectral irregularity
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Effects of Vertical Irregularity in Steel Braced Frames on Response to Earthquake
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作者 Md.Mahmud Sazzad Gazi Md.Sharfaraz Imam Azad +1 位作者 Md.SamdaniAzad Niloy Samadder 《Journal of Civil Engineering and Architecture》 2018年第2期106-112,共7页
This paper deals with the irregular profile of braced steel frame building in vertical direction with shear link bracing systems.The underlying fact of the paper is the effect of seismic force in braced frames with di... This paper deals with the irregular profile of braced steel frame building in vertical direction with shear link bracing systems.The underlying fact of the paper is the effect of seismic force in braced frames with different types of irregularities including mass irregularity,mass discontinuity and overhanging mass.For each successive model,the position of shear link bracings has been fixed to make the study effective.This study has investigated the vulnerable effect of irregular profiles in steel frame buildings.To attain the behavior of each frame,linear time history analysis method has been adopted for the present study.FEMA356 standard has been used here for linear time history analysis.Investigations on different frames exhibit that regular profile with symmetry in mass is more efficient while using overhanging mass is detrimental considering the time dependent displacements and accelerations. 展开更多
关键词 STEEL FRAME SHEAR link time HISTORY analysis irregular profile.
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Searching for Strange Attractor in Sliver Irregularity Series
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作者 姚杰 钟再敏 +1 位作者 陈人哲 叶国铭 《Journal of Donghua University(English Edition)》 EI CAS 2007年第6期718-722,共5页
The chaotic nonlinear time series method is applied to analyze the sliver irregularity in textile processing.Because it unifies the system's determinacy and randomness,it seems more adaptive to describe the sliver... The chaotic nonlinear time series method is applied to analyze the sliver irregularity in textile processing.Because it unifies the system's determinacy and randomness,it seems more adaptive to describe the sliver irregularity than conventional methods.Firstly,the chaos character,i.e.fractal dimension,positive Lyapunov exponent,and state space parameters,including time delay and reconstruction dimension,are calculated respectively.As a result,a positive Lyapunov exponent and a fractal dimension are obtained,which demonstrates that the system is chaotic in fact.Secondly,both local linear forecast and global forecast models based on the reconstructed state are adopted to predict a segment part of the sliver irregularity series,which proves the validity of this analysis.Therefore,the sliver irregularity series shows the evidence of chaotic phenomena,and thus laying the theoretical foundation for analyzing and modeling the sliver irregularity series by applying the chaos theory,and providing a new way to understand the complexity of the sliver irregularity much better. 展开更多
关键词 sliver irregularity CHAOS state space reconstruction time delay the maximal Lyapunov exponent fractal dimension local linear forecast global forecast neural network
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Generation of irregular particle packing with prescribed statistical distribution, spatial arrangement, and volume fraction
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作者 Libing Du Xinrong Liu +1 位作者 Yafeng Han Zhiyun Deng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第2期375-394,共20页
A method for packing irregular particles with a prescribed volume fraction is proposed.Furthermore,the generated granular material adheres to the prescribed statistical distribution and satisfies the desired complex s... A method for packing irregular particles with a prescribed volume fraction is proposed.Furthermore,the generated granular material adheres to the prescribed statistical distribution and satisfies the desired complex spatial arrangement.First,the irregular geometries of the realistic particles were obtained from the original particle images.Second,the Minkowski sum was used to check the overlap between irregular particles and place an irregular particle in contact with other particles.Third,the optimised advance front method(OAFM)generated irregular particle packing with the prescribed statistical dis-tribution and volume fraction based on the Minkowski sum.Moreover,the signed distance function was introduced to pack the particles in accordance with the desired spatial arrangement.Finally,seven biaxial tests were performed using the UDEC software,which demonstrated the accuracy and potential usefulness of the proposed method.It can model granular material efficiently and reflect the meso-structural characteristics of complex granular materials.This method has a wide range of applications where discrete modelling of granular media is necessary. 展开更多
关键词 Minkowski sum Optimised advance front method(OAFM) Spatial arrangement irregular particle packing Statistical distribution
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On the problem of the dynamical reactions of a rolling wheelset to real track irregularities
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作者 Hans True Lasse Engbo Christiansen +2 位作者 Andreas Lindhardt Plesner Andreas Lønstrup Ammitzbøll Bjørn Jerram Dahl 《Railway Engineering Science》 2023年第1期1-19,共19页
We investigate numerically the dynamical reactions of a moving wheelset model to real measured track irregularities.The background is to examine whether the dynamics are suitable as the input to the inverse problem:de... We investigate numerically the dynamical reactions of a moving wheelset model to real measured track irregularities.The background is to examine whether the dynamics are suitable as the input to the inverse problem:determine the true track geometry from measured wheelset dynamical reactions.It is known that the method works well for the vertical position of the rails but the computed lateral position is often flawed.We find that the lateral motion of the wheelset often may differ from the track geometry.The cases are investigated closely but the reasons remain unknown.While the wheelset dynamics reflect the larger(>4-6 mm)aperiodic track disturbances and single large disturbances quite well,this does not seem to be the case for general smaller or periodic track irregularities or sections behind single large disturbances.The resulting dynamics of a wheelset to lateral track irregularities are in general not sufficiently accurate to be used as the basis for a description of the track irregularities. 展开更多
关键词 Track monitoring Vehicle dynamical response Inverse problem Numerical analysis Estimate of errors Track irregularity
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Refined disturbance observer based prescribed performance fixed-time control of high-speed EMS trains with track irregularities
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作者 Yiran Xie Boyang Zhao Xiuming Yao 《High-Speed Railway》 2023年第3期171-178,共8页
High-speed Electromagnetic Suspension(EMS)train is continuously impacted by the irregularity of the track,which worsens the levitation performance of the train.In this paper,a composite control scheme for the EMS is p... High-speed Electromagnetic Suspension(EMS)train is continuously impacted by the irregularity of the track,which worsens the levitation performance of the train.In this paper,a composite control scheme for the EMS is proposed to suppress track irregularities by integrating a Refined Disturbance Observer(RDO)and a Prescribed Performance Fixed-Time Controller(PPFTC).The RDO is designed to estimate precisely the track irregularities and lumped disturbances with uncertainties and exogenous disturbances in the suspension system,and reduce input chattering by applying to the disturbance compensation channel.PPFTC is designed to converge the suspension air gap error to equilibrium point with prescribed performance by completing error conversion,and solve the fast dynamic issue of EMS.And the boundary of overshoot and steady-state is limited in the ranged prescribed.A theoretical analysis is conducted on the stability of the proposed control method.Finally,the effectiveness and reasonability of the proposed composite anti-disturbance control scheme is verified by simulation results. 展开更多
关键词 High-speed electromagnetic suspension train Track irregularity Refined disturbance observer Prescribed performance Fixed-time control
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