State Tracking Research Articles

Vertical dynamic measurements of a railway transition zone: a case study in Sweden

AbstractThis study presents a measuring framework for railway transition zones using a case study on the Swedish line between Boden and Murjek. The final goal is to better understand the vertical dynamics of transition zones using hammer tests, falling weight measurements, and axle box acceleration (ABA) measurements. Frequency response functions (FRFs) from hammer tests indicate two track resonances, for which the FRF magnitudes on the plain track are at least 30% lower than those at the abutment. The falling weight measurements indicate that the track on the bridge has a much higher deflection than the track on the embankment. Two features from ABA signals, the dominant spatial frequency and the scale average wavelet power, show variation along the transition zone. These variations indicate differences in track conditions per location. Finally, the ABA features in the range of 1.05–2.86 m−1 are found to be related to the track resonance in the range of 30–60 Hz. The findings in this paper provide additional support for physically interpreting train-borne measurements for monitoring transition zones.

Mechanical behavior and track geometry evaluation of long-span cable-stayed bridges with ballastless tracks

Ballastless tracks have been widely used in China’s high-speed railways; however, they have only recently been laid on 300 m-class cable-stayed bridges. For cable-stayed bridges with a longer span, the mechanical behavior of ballastless tracks is unclear, and the track construction acceptance method is incomplete, restricting the development of cable-stayed bridges with ballastless tracks. Taking four 300–1000 m-class cable-stayed bridges as research objects, this study established static track–bridge interaction models and dynamic vehicle–bridge coupled models. By evaluating static and dynamic indices, the feasibility of laying ballastless tracks and operating high-speed trains at 350 km/h on cable-stayed bridges was analyzed. Based on the results of dynamic analysis and track geometry evaluation, a 40 m chord was proposed for track geometry acceptance on cable-stayed bridges. The accuracy of the simulation results was verified through the measured data from the Xi-Cheng Railway. The numerical results showed that the 300–1000 m-class cable-stayed bridges with ballastless tracks had good static and dynamic characteristics. The 300 m baseline was unsuitable for the long-wave irregularity evaluation of tracks on cable-stayed bridges, and the 60 m chord was easily affected by wavelengths above 200 m, leading to misjudgment of the evaluation results. The 5 mm limits of the 40 m chord could be used for track geometry acceptance on cable-stayed bridges. Finally, a comprehensive evaluation method for track geometry, namely 10 m chord, 40 m chord, and minimum vertical curve radius, was formed.

A monitoring method of rail fastener reaction force based on iron pad strain

This research has successfully explored a monitoring method that does not necessitate modifications to the current structure of the fastening system and ensures that the intrinsic force distribution remains undisturbed, which is the pioneering use of Fiber Bragg Grating (FBG) strain sensors to test the strain of iron pads to reflect the force of fastener support points. Then, through the laboratory single-point loading test and finite element simulation, the feasibility of the monitoring method has been confirmed, and the resolution is higher than the traditional method. Subsequently, based on the experimental environment of high-speed railway commissioning, dynamic long-term monitoring research was conducted, and relevant calibration experiments and finite element simulation analyses were carried out. The experimental research and finite element simulation analysis revealed the superior ability of the method in capturing intricate data details, with the field experiment verifying a high resolution markedly surpassing other existing methods. Furthermore, by monitoring the same train, the data were found to be highly repeatable, which confirmed the ability of the monitoring method to stably reflect the dynamic behavior of the train. Overall, the monitoring method provided in this research could monitor the fastener reaction force in real time for an extended period and accurately record its periodic dynamic loading cycle pattern, which provides important data support for the structural health condition of the ballastless track and the safe operation assessment of trains.

Safe tracking control based on a secure boundary protection method for nonlinear systems with unknown initial tracking condition

Aiming to the sudden change of the system actual output constraint, a novel safe tracking control strategy is investigated for a class of non-strict feedback nonlinear systems with unknown initial tracking condition in this paper. A secure boundary protection method (SBPM) based on prescribed performance and a new prescribed finite-time performance function (PFTPF) are proposed. The SBPM can automatically construct two adjustable secure boundaries, so that the system output meets both the control performance prescribed by the PFTPF and the secure boundary constraint. In order to solve the problem of the excessive control input jitter caused by the sudden change of output constraint, a bidirectional filtering smoothing mechanism (BFSM) is proposed. The proposed SBPM can effectively ensure the safe tracking control of the system with unknown initial tracking condition when the actual output constraint changes suddenly, and ensure that the system has the prescribed finite-time control performance given by the PFTPF. Differently from the existing works, the system output will be strictly constrained into the actual output constraint without the prediction for the system output value. Finally, the effectiveness of this proposed method is verified by simulations.

Abstract TP49: State of the Florida Stroke Coordinator: Hospital Inventory Survey Insights

Background: Stroke coordinators (SC’s) are essential leaders of certified stroke centers which facilitate evidence-based stroke care, improving patient outcomes. Although this role has existed since the 1970’s, significant variability of responsibilities and staffing exists. Evidence based recommendations for SC staffing are scarce. Purpose: Utilizing the 2023 Florida Stroke Registry Hospital Inventory Survey (HIS), we describe current SC roles, responsibilities, and challenges in Florida. Methods: The Florida Stroke Registry (FSR), with state funding, tracks and measures Florida’s stroke center performance. FSR recently deployed the FSR HIS, a ten-part questionnaire examining various aspects of stroke program infrastructure. The survey was disseminated to 171 sites with 38 responses in the first wave. This is preliminary data from an HIS section focusing on SC staffing, workload, resources, and perceived challenges. Results: Responding sites all report a designated SC. Figure 1 describes SC’s Status (full vs. part-time), onboarding, and resources. Of note, only 35% of SC’s manage stroke full-time at a single site, SC turnover rate is high with 63% in the role <4 yrs. Stroke coordinators abstract for multiple databases, even with data abstractor support. In free-text responses, 58% (19/33) of SC’s cited lack of time and/or corporate structure for adequate program management as the biggest challenges in their role. Discussion: The preliminary study highlights significant challenges with high SC turnover, heavy workloads, and insufficient support. Stroke programs lack clear recommendations from certifying bodies for program personnel based on program volume. Future directions of FSR HIS include conducting additional dissemination waves, and an analysis of optimal stroke program staffing by cross-referencing certification level, patient volume and SC resources.

On the hysteresis characteristics and compensation control strategy of a pneumatic hydrodynamic retarder

As the core component of the hydrodynamic retarder braking system, pneumatic proportional solenoid valve plays an important role in the process of braking torque control. However, the hysteresis characteristic caused by friction and air compressibility will lead to the deviation of braking torque. In order to solve this problem, the hysteresis characteristic of pneumatic proportional solenoid valve is experimentally studied, and the causes of hysteresis phenomenon are analyzed through mathematical modeling of the valve core. Then, a high-precision prediction model of braking torque is obtained by combining Computational Fluid Dynamics (CFD) and response surface method, which is used to construct the mapping relationship between control air pressure and braking torque. Furthermore, a feedforward controller based on Prandtl–Ishlinskii inverse model is designed to compensate the hysteresis characteristics. On this basis, a compound hysteresis characteristics compensation control strategy combined with Proportional Integral Derivative (PID) feedback control is proposed to realize the accurate control of braking torque. Finally, the test verification of braking torque control is carried out. The average error of compound control, feedforward control, and PID control under torque step working condition is 3.16%, 5.97%, and 6.23%, and the response time is 3.75, 8.75, and 3.2 s, respectively. The compound control strategy also has smaller torque error and shorter response time under both ramp torque tracking and constant torque conditions. To sum up, this compound control strategy can effectively compensate the hysteresis characteristics of the pneumatic hydrodynamic retarder and ensure the driving safety by improving the control accuracy and response speed of braking torque.

Robust exponential arbitrary time control of nonlinear systems with input delay

In this study, we aim to present an exponential arbitrary-time control scheme for nonlinear systems subjected to input time delay and additive disturbances. To this end, a new finite-time controller was developed for certain nonlinear systems, which ensures exponential tracking in a time independent of initial conditions. Due to the presence of unknown disturbances, predictors cannot be directly used to control the system, being a challenging issue. Therefore, to utilize predictor feedback in disturbed nonlinear input delay systems, a disturbance observer was designed. The proposed disturbance observer guarantees the exponential arbitrary time estimation of unknown disturbances. Next, an adaptive exponential arbitrary time controller was designed for the system using the proposed disturbance observer. In addition, the Lyapunov theorem was utilized to prove the disturbance observer and tracking errors converged to the origin in an arbitrary time. In the end, the state tracking error was analyzed accurately. It was ensured that the upper bound of the tracking error was bounded and converged to zero in the adjusted arbitrary time. Ultimately, the main results of this study will be illustrated and validated by simulation and experimental results.

An innovative approach to continuously monitor rail track surface displacement during freezing-thawing seasons

Large differential displacement as a result of freeze–thaw cycles (FTC) is a major issue affecting the safety and performance of railway tracks constructed in cold regions. Current track monitoring methods in winter are mainly based on visual inspection and manual measurements. The frequency of FTC is expected to increase under future climate and thus it is essential for railway operators to employ new methods of inspection that allow continuous and remote monitoring of railway tracks during the freeze–thaw period. While sensors are commonly used to measure localized track displacement, the advantages and limitations of using instruments that are capable of collecting data over a segment of track is not well understood. This paper investigates the use of a micro electro-mechanical sensor (MEMS) based instrument for monitoring surface displacement of railway tracks during FTC. The ShapeArray™ instrument, in this case the SAAX inclinometer, is a MEMS based sensor that was selected due to its ability to collect data over a segment of track (up to 150 m). Two sets of SAAX inclinometers were installed on a 50-metre section of track to measure data during two freezing-thawing periods. Analysis of the field data suggests that the main limitation of using MEMS-based sensors is their sensitivity to fluctuations of ambient temperature which may be confused with their responses to actual track displacement. A data analysis technique has been developed to remove the unwanted variations so that the instrument can be effectively used for monitoring track displacement during FTC. The comparison of the processed measurements with data collected from a digital level suggested that it provides a reasonably accurate measure of track surface displacement. Overall, the limited investigations in this project suggests that using MEMS-based sensor along with proper data processing techniques can provide useful information about the differential displacement over a segment of track, a key parameter for the safety of railway operation. The measurements can also be transferred through the cloud, enabling track engineers to remotely monitor track condition in near-real-time without the need to access the track and interrupt trains operations.

Design Strategy and Implementation of Control Parameters for BLDC Motor Application in an Electric Vehicle

The brushless dc motor (BLDC) motor is an electric motor that is widely utilized in numerous applications, especially in automotive systems. It is significant to maximize the force of the electric vehicle; however, due to the rapid growth of electric vehicles, motors and power electronics are determined with huge concern. Meanwhile, the Proportional Integral Derivative (PID) cannot balance the load in a stable condition, and this variation generates a change in load and track conditions. In mobile robot the BLDC motor diminished the current and it increased the torque voltage and current by 48V and 50A, respectively. So to overcome these issues, the control algorithm is implemented in this paper to regulate the speed of the motor in 1KW BLDC in an Electric Vehicle (EV). A 1500rpm BLDC motor is designed by Dymola software which is evaluated with MATLAB. The BLDC increases the torque speed characteristics of the motor based on the pole configuration of an electric vehicle. Evaluation of the method is determined with a set of STM 31 ARM processors and a 750 watt driver. The experimentation is simulated using Arduino IDE software and the results revealed that it is applicable for STM 32 or teensy 3.2 development board or Arduino Mega development board.

Adaptive terminal sliding mode trajectory tracking control with fixed‐time prescribed performance considering rollover stability of autonomous vehicles

SummaryIn the face of external disturbances, the autonomous vehicle with a high center of gravity is exposed to the risk of roll instability during trajectory tracking. To this end, this paper aims to propose a vector‐extended‐state‐observer (VESO)‐based adaptive fixed‐time terminal sliding mode prescribed performance control strategy, which coordinates the front wheel steering angle and external roll moment to ensure the roll stability of the high center of gravity autonomous vehicle while improving the tracking dynamic and steady state performances. The VESO for estimating the external disturbance is designed to enhance the robustness outside the sliding mode surface, based on which the adaptive updating laws compensate the estimation errors to provide the control system's dynamic performance. A fixed‐time sliding mode control with prescribed performance is proposed, which combines a fixed‐time prescribed performance control method to further improve the transient performance and steady‐state accuracy. The double lane‐changing reference trajectory tracking conditions under different vehicle driving speeds and initial errors settings are verified by simulation in MATLAB/Simulink environment, and the results show that the proposed control strategy can ensure the rolling stability of the vehicle, can track the reference trajectory accurately and quickly, and has strong robustness.

Building a Better Roadmap toward a Green Economy through Advanced Rooftop Solar Mapping and Enhanced Energy Yield

Objective: This study aims to develop a transparent roadmap for the implementation of rooftop solar (RTS) systems to boost solar energy adoption, addressing the lack of a definitive solar roadmap. The objective is to utilize Helioscope solar software to envision the maximum shadow-free area over building rooftops and simulate energy generation potential using fixed tilt-based and monthly optimum tilt-angle control-based solar photovoltaics systems. Methods: The research employs HelioScope software to estimate shadow-free rooftop areas of government buildings in an Indian state, considering both fixed-tilt and optimum tilt angle control-based solar tracking systems. The study validates monthly optimum tilt angles for different districts and presents an experimental setup with a 2kWp RTS system. Results: The district-wise analysis reveals the useful rooftop area and energy generation potential, indicating an increase in annual solar energy yield with the implementation of an optimum tilt angle control-based tracking system. The results suggest that chronological implementation based on available rooftop area can aid in achieving the mandated RTS target. Conclusion: The proposed methodology provides a guideline for developing a transparent RTS installation roadmap. The study highlights the potential of an 8% increase in annual solar energy yield by incorporating monthly optimum tilt angle control. The district-wise spatial differences in solar energy production serve as a prototype for other states and countries, facilitating effective solar mapping and policy planning for RTS installations.

Development of track component health indices using image-based railway track inspection data

The primary role of the US Department of Transportation (USDOT) Federal Railroad Administration (FRA) is ensuring the safe operation of railway rolling stock and infrastructure by way of regulatory oversight. FRA regulations require US railroads to conduct visual track inspections as often as twice per week depending on a specific track segment’s FRA track class, which also governs maximum train operating speed. Such inspections are often subjective due to the inherent limitations of human visual inspection and cognition. Additionally, human visual inspections require some level of risk given the need for inspectors to be on track while also consuming valuable network capacity. As a result, and the desire to collect objective data to improve both safety and maintenance planning, railroads are pursuing new means and methods to assess track condition and evaluate track component health. This paper presents a numerical method to define track component health using field data collected on the High Tonnage Loop (HTL) at the Transportation Technology Center (TTC) in Pueblo, Colorado, USA. Line scan laser and image data of the track were captured using a 3D Laser Triangulation system and were subsequently processed using Deep Convolutional Neural Networks (DCNNs). The track heath quantification method proposed establishes benchmarks that were developed based on the understanding of railway track mechanics, high axle load (HAL) railroad engineering instructions, and FRA regulations. The novel metrics presented are referred to as Track Component Heath Indices (TCHIs) and are quantitative values that objectively assess track condition and provide a means to monitor condition change with time and tonnage. These data can be used in conjunction with traditional track geometry and other forms of track heath data (e.g. GPR and rail profile) to more holistically assess the condition of the track structure and its components and ultimately predict its future state.

Multi-domain gate and interactive dual attention for multi-domain dialogue state tracking

Multi-domain dialogue state tracking (MDST) is a crucial component of task-oriented dialogue systems. In the context of multi-turn dialogues between the user and the system, MDST necessitates the continuous keeping track of dialogue states based on the information present in the current dialogue utterance and the dialogue states from the preceding turn. Recent work achieves the successful execution of multi-domain dialogue tasks by adopting an approach that treats each state as an individual label, while regrettably neglecting the potential benefits of incorporating domain-specific information associated with these states. Simultaneous, existing models exhibit a deficiency in effectively modelling the explicit correlations between dialogue contextual semantics and dialogue states. In this paper, we introduce the modules of multi-domain gate and interactive dual attention as novel solutions to address the aforementioned concerns. For the efficient exploitation of domain-specific information within states, we leverage the multi-domain gate as indices to amplify the states pertinent to the current utterance domain while filtering out irrelevant states. Interactive dual attention comprises utterance attention and slot attention, effectively modelling the correlation between dialogue utterances and slots. Additionally, interactive dual attention ensures that each dialogue utterance interacts with the slots once to derive all state updates, thereby ensuring computational efficiency. Specifically, slot attention models the associations between slots by incorporating semantic features to forecast updates in slot values. Meanwhile, utterance attention captures the semantics of dialogue context and integrates it with slot name features to generate dialogue states. All the aforementioned modules are designed based on a slot-independent framework, enabling efficient scalability of slots and circumventing issues related to model input limitations. The experimental results on the multi-domain dialogues dataset MultiWOZ 2.4 demonstrate the superior performance of our model compared to the baselines. Additionally, we conduct a comprehensive analysis of the effectiveness of the multi-domain gate and interactive dual attention modules, elucidating their contribution to the performance of the model through visualization and case studies.

Rapid and Precise Measurement Method for Track Static Geometry of Large-Span Bridge Railway

Track geometry is an important parameter reflecting the safety of bridge railway, which is of great significance for the structure control of railway track. The measurement of track geometry is an indispensable part of structural health monitoring for bridge railway. However, existing methods for track static track geometry measurement are inadequate in terms of accuracy and efficiency. In order to improve the measurement method, this paper proposes a rapid and precise measurement method based on IMU/odometer aided by multiple total stations, which has the advantages of high efficiency, high accuracy, and is less affected by the environment. The proposed method uses a track measurement trolley (TMT) integrated with IMU and an odometer to collect railway track data on the bridge, and multiple total stations are used to synchronously measure the three-dimensional coordinates of the TMT. After coordinate system registration and time synchronisation, the data are then fused using a filtering algorithm to finally obtain the static geometry of the railway track. The proposed method was validated on the NanSha Port Railway Bridge across the Xijiang River in Foshan, China, and the results showed that the proposed method can make a single on-orbit measurement of a 1000 m length of large-span bridge railway track within half an hour, with an accuracy on the order of millimetres. The proposed method has obvious advantages in terms of efficiency and accuracy and is therefore an effective new measurement method with practical significance.

Decentralized model reference adaptive control for interconnected systems with time‐varying delays and unknown dead‐zone inputs

AbstractIn this study, the decentralized model reference adaptive control (DMRAC) problem is tackled for a class of time‐varying delay interconnect systems that comprise unknown system matrices and unknown dead‐zone inputs. Two robust adaptive control methods are proposed for state tracking based on the moderate matching time‐varying delay nonlinear assumptions and the matching between the controlled system and reference model matrices, respectively. The control gain function is explicitly expressed, and it is applied to the adaptive law gains simultaneously. Moreover, a Lyapunov–Krasovskii functional with two integral functions is developed. Besides the properties of the type‐B Nussbaum function, the circumstance where the system parameters are fully unknown is considered. As indicated by the results, all signals in the closed‐loop system are bounded while fulfilling asymptotically tracked control objectives. The simulation example of this study verifies the effectiveness and feasibility of the proposed design method.

Выбор и проверка метода схематизации случайного процесса нагружения пружин буксового подвешивания

The product life cycle contract also contains its cost for the preparation of the product, delivery to the supplier, subsequent maintenance, operation and repair of the product up to disposal. The article considers the development of a methodology for calculating the life cycle of axle box suspension springs (and later frames) of the Lastochka electric train trolley. The method of analysis is based on the assessment of the spring strength and the results of strength tests obtained during sea trials. These tests have been carried out on separate operating sections of railways, based on the results of data from the removed blocks of oscillograms recording forces from models of electric train bogies of virtual sea trials. Virtual sea trials have been conducted on certain created sections of the track, taking into account the horizontal and vertical irregularities of the track for different track conditions. The paper analyzes the tutorials on the methods for schematization of test results in the form of oscillograms recording the forces of random processes; the method of falling rain is used. The implementation in the software product of the methodology for analyzing the stress-strain state of box suspension springs and the results of sea trials, which have been proceed by the falling rain method, allows us to determine the actual service life of box suspension springs.

Innovative Trends in Railway Condition Monitoring

Provision of functional safety of a railway track requires complementing the existing system of assessment of the railway track condition with the stress-strain behaviour assessment of the rail substructure, i.e. the assessment of the effect of track structure elasticity on the change of its geometric parameters during rolling stock passage over time. There is a lack of available theoretical and practical information about any pivotal changes in this field of science. The subject of the study is the in-situ elasticity indicators of a railway track and geometric monitoring indicators of railway structure condition or similar indicators obtained by numerical processing of data provided by the measuring systems of a track recording car and enabling the determination of change of irregularity parameters over time taking into account of the tonnage passed. The outcome of the investigation is the proposed approach to the development of an unparalleled diagnostic loading system which has been the missing part of the “puzzle” in the existing system of integrated assessment of the technical condition of a railway track.

Image segmentation method of rail head defects and area measurement of selected segments

The operation safety of railway transport, which is the most important economic and social factor, is largely determined by the technical condition of the rail track and measures to maintain the quality of its track management system. One of the system elements for ensuring the accident-free operation of the track is the technical diagnosis of rails using a method complex of non-destructive control of rails, such as acoustic (ultrasonic), magnetic, combined, etc., and monitoring of the track using methods of measuring the geometry of the rail track and its disturbances. When the wheel interacts with the rail, especially on high-speed and load-stressed sections, defects and damage inevitably occur in the rails. A rather large share of such defects are on the rolling surface of the rail head. Formed defects develop rapidly, which seriously complicates the safety of train traffic. Therefore, accurate and quick detection of defects on the rolling surface of the rail head is very important. However, it is quite difficult to detect defects on the rolling surface of the rail by the acoustic (ultrasound) method due to the violation of tight contact between the rolling surface of the rail head and the piezoelectric transducer. In this case, it is quite convenient to detect surface defects of the rail head using video control. The article provides a comparative analysis of segmentation methods. There has been presented the method of image segmentation of main rail defects based on general contour preparation and parallel-hierarchical (PH) transformation using their classification. The parallel-hierarchical transformation method allows to increase the segmentation accuracy of individual areas in the original image compared to similar ones. The algorithm of pyramidal generalized-contour preparation and the criterion system allows, by calculating the threshold for each level of the gray scale, to present the study of the image with the corresponding contour preparations at the segmentation level. Modeling of recursive generalized-contour preparation and PH transformation method for image segmentation problem of rail head defects shows that, compared to the segmentation method based on the increase of areas, the accuracy of image segmentation is better. A modified method of calculating the image contour area based on the coding of lines forming the boundaries of the black and white areas of the two-gradation image has been given.

Analysis of Excavation Method on Inlet Tunnel of Controller Construction of Rukoh Dam Pidie District – Aceh Province

The tunnel of controller construction is located in Panton Bunot Village, Tiro Sub District, Pidie District, Aceh Province. The tunnel construction aims to flow the water from Kr. Tiro River to Rukoh inundation for water supply to Rukoh Dam in Keumala Sub District, Pidie District. The research aimed to comprehend engineering geological condition in the study area and determine excavation method at the inlet and proper tunnel support system. The determination of proper excavation method becomes crucial and it is required in maintaining affectivity and efficiency during tunnel construction process. Than excavation method determination is carried out calculation by using empirical method based on output parameter of laboratory test to the rock samples from core drilling in the tunnel track. The outputs are rock conditions as rock mass quality (RQD), discontinuity area density of the rock and rock stress strength. The condition of tunnel track was dominated by silt stone having very poor quality. UCS value was 3 Mpa – 10 Mpa. Joins spacing was less that 60 mm. Empirical analysis of excavation method explained that tunnel opening of Rukoh Controller Construction was highly weathered (HW) and required ripping as excavation type.

Smart Farming System Based on Cloud Computing Technologies

Smart farming is a new concept that can be described as applying different kinds of modern technology to make farming more efficient. One such technology is the Internet of Things, an extension of the Internet and other connections into mundane devices. This paper uses dedicated sensors and cloud computing technologies to model a smart farming system that helps farmers keep track of state of the crops and livestock. It also covers implementing and testing an Android tracker app that is supposed to become the first component of the mentioned system, a client application that communicates with the cloud computing services yet to be implemented. The end product provides its users with an easy way of keeping track of the state of their farms, simplifying the farmers’ work and enhancing productivity.