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Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy

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Journal of Semiconductors 2024年第10期45卷 35-41页

作者： Pedram Jahandar maksym Myronov Department of Physics University of WarwickCoventryCV47ALUnited Kingdom

The growth of high-quality germanium tin(Ge_(1–y)Sn_(y))binary alloys on a Si substrate using chemical vapor deposition(CVD)techniques holds immense potential for advancing electronics and optoelectronics applications,including the development of efficient and low-cost mid-infrared detectors and light ***,achieving precise control over the Sn concentration and strain relaxation of the Ge_(1–y)Sn_(y)epilayer,which directly influence its optical and electrical properties,remain a significant *** this research,the effect of strain relaxation on the growth rate of Ge_(1–y)Sn_(y)epilayers,with Sn concentration>11at.%,is *** is successfully demonstrated that the growth rate slows down by~55%due to strain relaxation after passing its critical thickness,which suggests a reduction in the incorporation of Ge into Ge_(1–y)Sn_(y)growing *** the increase in Sn concentration as a result of the decrease in the growth rate,it has been found that the Sn incorporation rate into Ge_(1–y)Sn_(y)growing layers has also decreased due to strain *** valuable insights could offer a foundation for the development of innovative growth techniques aimed at achieving high-quality Ge_(1–y)Sn_(y)epilayers with tuned Sn concentration and strain relaxation.

关键词： GeSn germanium tin strain relaxation groupⅣsemiconductor chemical vapour deposition CVD

Strategies on the application of stem cells based therapies for the treatment of optic neuropathies

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Neural Regeneration Research 2021年第6期16卷 1190-1191页

作者： Sanaz Behtaj maksym Rybachuk School of Engineering and Built Environment Griffith UniversityParklands DriveSouthportQueenslandAustralia Department of Cellular Biotechnology Cell Science Research CentreRoyan Institute for BiotechnologyIsfahanIran Queensland Micro-and Nanotechnology Centre Griffith UniversityNathanQueenslandAustralia School of Engineering and Built Environment Griffith UniversityNathanQueenslandAustralia

The retinal ganglion cells(RGCs)are not able to regenerate following optic nerve injury resulting in an irreversible vision loss in patients with optic neuropathies including *** findings in ocular regeneration have opened promising avenues to apply stem cell-based modalities to restore vision in progressive optic *** cellbased therapies can help to improve retinal regeneration by solving two major problems:(1)by preventing secondary degeneration of RGCs and preserving the remaining vision,and(2)by replacing degenerated RGCs and promoting RGC axon regeneration in the damaged area.

关键词： degeneration treatment irreversible

Coupler force and fatigue assessments with stochasticdraft gear frictions

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第1期10卷 1-12页

作者： Qing Wu Colin Cole maksym Spiryagin Centre for Railway Engineering Central Queensland UniversityRockhamptonQLD 4701Australia

Train dynamics and component fatigue assessments are important steps towards successful operations of long heavy haul *** train dynamics(LTD)simulation is an effective and efficient approach in this *** gear friction has been known to have a strong stochastic ***,relevant train dynamics simulations have not been reported in open *** paper uses experimental data to extract the stochastic feature of draft gear *** stochastic feature is then introduced into LTD *** force and fatigue damage assessments were conducted by simulating a heavy haul train that has 244 vehicles and weighs nearly 30,000 *** results show that average in-train force variations due to stochastic friction were 55 and 40 kN for the traction and air brake cases respectively;maximum force variations were 207 and 98 kN for the traction and air brake cases *** fatigue calculations are even more sensitive to stochastic draft gear friction;the largest variations can be up to 700 times different due to the strong nonlinearity of fatigue calculation *** friction is an unavoidable nature in friction draft *** using stochastic draft gear friction can deliver results that are more robust and reliable.

关键词： Stochastic friction Draft gear Train dynamics Coupler fatigue Laboratory testing

State and Mode Feedback Control for Discrete-time Markovian Jump Linear Systems With Controllable MTPM

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IEEE/CAA Journal of Automatica Sinica 2019年第3期6卷 830-837页

作者： Jin Zhu Qin Ding maksym Spiryagin Wanqing Xie IEEE the Department of Automation University of Science and Technology of China the Centre for Railway Engineering Central Queensland University the School of Information Science and Technology University of Science and Technology of China

In this note, the state and mode feedback control problems for a class of discrete-time Markovian jump linear systems(MJLSs) with controllable mode transition probability matrix(MTPM) are investigated. In most achievements, controller design of MJLSs pays more attention to state/output feedback control for stability, while the system cost in practice is out of consideration. In this paper, we propose a control mechanism consisting of two parts: finite-path-dependent state feedback controller design with which uniform stability of MJLSs can be ensured, and mode feedback control which aims to decrease system cost. Differing from the traditional state/output feedback controller design, the main novelty is that the proposed control mechanism not only guarantees system stability, but also decreases system cost effectively by adjusting the occurrence probability of system modes. The effectiveness of the proposed mechanism is illustrated via numerical examples.

关键词： Controllable mode transition probability matrix(MTPM) Markovian jump linear systems(MJLSs) stabilization system cost

Recent advances in wheel–rail RCF and wear testing

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摩擦:英文版 2023年第12期11卷 2181-2203页

作者： Sundar SHRESTHA maksym SPIRYAGIN Esteban BERNAL Qing WU Colin COLE Centre for Railway Engineering Central Queensland UniversityRockhampton 4701Australia Australasian Centre for Rail Innovation Canberra 2601Australia

The wear and rolling contact fatigue (RCF) testing approaches for wheels and rails have been reviewedand evaluated in this study. The study points out the advantages and limitations of the existing approaches. Thebroad analysis revealed that scaled laboratory-based wear testing is widely applied. However, it is necessary topredetermine the input parameters and observing parameters for scaled wear testing for three reasons: first, toemulate the real-world scenarios as closely as possible;second, to postprocess the results received from the scaledtesting and transfer them into real practice at full scale;third, to present the results in a legible/appropriate ***, most of the important parameters required for wear testing have been discussed with fundamental andsystematic explanations provided. Additionally, the transition of the parameters from the real-world into the testdomain is explained. This study also elaborates on the challenges of the RCF and wear testing processes andconcludes by providing major considerations toward successful testing.

关键词： wear testing rolling contact fatigue(RCF)testing wheel-rail

Experimental prototyping of the adhesion braking control system design concept for a mechatronic bogie

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Railway Engineering Science 2021年第1期29卷 15-29页

作者： Sundar Shrestha maksym Spiryagin Qing Wu Centre for Railway Engineering Central Queensland UniversityRockhamptonAustralia Rail Manufacturing Cooperative Research Centre(CRC) MelbourneVICAustralia

The dynamic parameters of a roller rig vary as the adhesion level *** change in dynamics parameters needs to be analysed to estimate the adhesion *** of these parameters is noise emanating from wheel–rail *** previous wheel–rail noise analysis has been conducted to mitigate those ***,in this paper,the noise is analysed to estimate the adhesion condition at the wheel–rail contact interface in combination with the other methodologies applied for this *** adhesion level changes with changes in operational and environmental *** accurately estimate the adhesion level,the influence of those factors is included in this *** testing and verification of the methodology required an accurate test prototype of the roller *** general,such testing and verification involve complex experimental works required by the intricate nature of the adhesion process and the integration of the different subsystems(***,traction,braking).To this end,a new reduced-scale roller rig is developed to study the adhesion between wheel and rail roller *** various stages involved in the development of such a complex mechatronics system are described in this ***,the proposed brake control system was validated using the test rig under various adhesion *** results indicate that the proposed brake controller has achieved a shorter stopping distance as compared to the conventional brake controller,and the brake control algorithm was able to maintain the operational condition even at the abrupt changes in adhesion condition.

关键词： Wheel–rail adhesion condition Brake controlMechatronics scaled bogie test rig Wheel–rail noiseAcoustic analysis

Real-time multibody modeling and simulation of a scaled bogie test rig

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Railway Engineering Science 2020年第2期28卷 146-159页

In wheel–rail adhesion studies,most of the test rigs used are simplified designs such as a single wheel or wheelset,but the results may not be ***,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in *** trade off accuracy over complexity,a bogie model can be the optimum ***,only a real-time model can replicate its physical counterpart in the time *** such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time ***,the influence of the control system has not been included in those *** address these issues,a real-time scaled bogie test rig including the control system is ***,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller *** compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody *** model is the complete model of the test rig which delivers more precise *** exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive ***,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in rigs used are simplified designs such as a single wheel or wheelset,but the results may not be ***,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in *** trade off accuracy over complexity,a bogie model can be the optimum ***,only a real-time model can replicate its physical counterpart in the time *** such a model requires broad expertise and appropriate software and hardware.A few pub

关键词： Bogie modeling Scaled bogie test rig Realtime simulation Wheel-rail adhesion Software in loop

Train energy simulation with locomotive adhesion model

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Railway Engineering Science 2020年第1期28卷 75-84页

作者： Qing Wu maksym Spiryagin Colin Cole Centre for Railway Engineering Central Queensland UniversityRockhamptonAustralia

Railway train energy simulation is an important and popular research *** traction force simulations are a fundamental part of such *** energy calculation models are not able to consider locomotive wheel-rail adhesions,traction adhesion control,and locomotive *** paper has developed two models to fill this research *** first model uses a 2D locomotive model with 27 degrees of freedom and a simplified wheel-rail contact *** second model uses a 3D locomotive model with 54 degrees of freedom and a fully detailed wheel-rail contact *** models were integrated into a longitudinal train dynamics model with the consideration of locomotive adhesion *** consumption simulations using a conventional model(1D model)and the two new models(2D and 3D models)were conducted and *** results show that,due to the consideration of wheel-rail adhesion model and traction control in the 3D model,it reports less energy consumption than the 1D *** maximum difference in energy consumption rate between the 3D model and the 1D model was 12.5%.Due to the consideration of multiple wheel-rail contact points in the 3D model,it reports higher energy consumption than the 2D *** 8.6%maximum difference in energy consumption rate between the 3D model and the 1D model was reported during curve negotiation.

关键词： Energy consumption Adhesion model Traction control Longitudinal train dynamics Parallel co-simulation

A review on design and testing methodologies of modern freight train draft gear system

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Railway Engineering Science 2021年第2期29卷 127-151页

作者： Simon Wagner Colin Cole maksym Spiryagin Centre for Railway Engineering Central Queensland UniversityRockhamptonAustralia

Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the *** paper focuses on the evolution of both connection and stiffness damping *** is on freight rolling stock,but passenger draw gears are also *** was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide *** versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet *** the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning *** with the single compressive draft gear units balanced and floating plate configurations are also *** draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

关键词： Railway Draft gear Coupler Rollingstock Freight train