A framework for dynamic modelling of railway track switches considering the switch blades,actuators and control systems

The main contribution of this paper is the development and demonstration of a novel methodology that can be followed to develop a simulation twin of a railway track switch system to test the functionality in a digital environment.This is important because,globally,railway track switches are used to allow trains to change routes;they are a key part of all railway networks.However,because track switches are single points of failure and safety-critical,their inability to operate correctly can cause significant delays and concomitant costs.In order to better understand the dynamic behaviour of switches during operation,this paper has developed a full simulation twin of a complete track switch system.The approach fuses finite element for the rail bending and motion,with physics-based models of the electromechanical actuator system and the control system.Hence,it provides researchers and engineers the opportunity to explore and understand the design space around the dynamic operation of new switches and switch machines before they are built.This is useful for looking at the modification or monitoring of existing switches,and it becomes even more important when new switch concepts are being considered and evaluated.The simulation is capable of running in real time or faster meaning designs can be iterated and checked interactively.The paper describes the modelling approach,demonstrates the methodology by developing the system model for a novel“REPOINT”switch system,and evaluates the system level performance against the dynamic performance requirements for the switch.In the context of that case study,it is found that the proposed new actuation system as designed can meet(and exceed)the system performance requirements,and that the fault tolerance built into the actuation ensures continued operation after a single actuator failure.

Distributed Dynamic Load in Structural Dynamics by the Impulse-Based Force Estimation Algorithm

This paper proposes a novel approach for identifying distributed dynamic loads in the time domain.Using polynomial andmodal analysis,the load is transformed intomodal space for coefficient identification.This allows the distributed dynamic load with a two-dimensional form in terms of time and space to be simultaneously identified in the form of modal force,thereby achieving dimensionality reduction.The Impulse-based Force Estimation Algorithm is proposed to identify dynamic loads in the time domain.Firstly,the algorithm establishes a recursion scheme based on convolution integral,enabling it to identify loads with a long history and rapidly changing forms over time.Secondly,the algorithm introduces moving mean and polynomial fitting to detrend,enhancing its applicability in load estimation.The aforementioned methodology successfully accomplishes the reconstruction of distributed,instead of centralized,dynamic loads on the continuum in the time domain by utilizing acceleration response.To validate the effectiveness of the method,computational and experimental verification were conducted.

Large System Analysis of Downlink C-RAN with Phase Noise and Fronthaul Compression

This paper studies the effect of phase noise and fronthaul compression on a downlink cloud radio access network(C-RAN), where several remote radio heads(RRHs) are coordinated to communicate with users by a baseband unit(BBU) on the cloud server. In the system, the baseband signals are precoded at BBU, and then compressed before being transmitted to RRHs through capacity-limited fronthaul links which results in the compressive quantization noise. We assume the regularized zero-forcing precoding is performed with an imperfect channel state information and a compression strategy is applied at BBU. The effect of phase noise arising from nonideal local oscillators both at RRHs and users is considered. We propose an approximate expression for the downlink ergodic sum-rate of considered C-RAN utilizing large dimensional random matrix theory in the large-system regime. From simulation results, the accuracy of the approximate expression is validated, and the effect of phase noise and fronthaul compression can be analyzed theoretically based on the approximate expression.

Research on encoding and decoding of non-binary polar codes over GF(2m)

Binary Polar Codes (BPCs) have advantages of high-efficiency and capacity-achieving but suffer from large latency due to the Successive-Cancellation List (SCL) decoding. Non-Binary Polar Codes (NBPCs) have been investigated to obtain the performance gains and reduce latency under the implementation of parallel architectures for multi-bit decoding. However, most of the existing works only focus on the Reed-Solomon matrix-based NBPCs and the probability domain-based non-binary polar decoding, which lack flexible structure and have a large computation amount in the decoding process, while little attention has been paid to general non-binary kernel-based NBPCs and Log-Likelihood Ratio (LLR) based decoding methods. In this paper, we consider a scheme of NBPCs with a general structure over GF(2m). Specifically, we pursue a detailed Monte-Carlo simulation implementation to determine the construction for proposed NBPCs. For non-binary polar decoding, an SCL decoding based on LLRs is proposed for NBPCs, which can be implemented with non-binary kernels of arbitrary size. Moreover, we propose a Perfect Polarization-Based SCL (PPB-SCL) algorithm based on LLRs to reduce decoding complexity by deriving a new update function of path metric for NBPCs and eliminating the path splitting process at perfect polarized (i.e., highly reliable) positions. Simulation results show that the bit error rate of the proposed NBPCs significantly outperforms that of BPCs. In addition, the proposed PPB-SCL decoding obtains about a 40% complexity reduction of SCL decoding for NBPCs.

Development of 3D Scanning System for Robotic Plasma Processing of Medical Products with Complex Geometries

This paper describes the development of an intelligent automated control system of a robot manipulator for plasma treatment of medical implants with complex shapes.The two-layer coatings from the Ti wire and hydroxyapatite powders are applied on the surface of Ti medical implants by microplasma spraying to increase the biocompatibility of implants.The coating process requires precise control of a number of parameters,particularly the plasma spray distance and plasma jet traverse velocity.Thus,the development of the robotic plasma surface treatment involves automated path planning.The key idea of the proposed intelligent automatic control system is the use of data of preliminary three-dimensional (3D) scanning of the processed implant by the robot manipulator.The segmentation algorithm of the point cloud from laser scanning of the surface is developed.This methodology is suitable for robotic 3D scanning systems with both non-contact laser distance sensors and video cameras,used in additive manufacturing and medicine.

Ultrasonically Assisted Cutting of Histological Sections for Reducing the Environmental and Financial Impact of Microtomy

Modern-day microtomy requires high precision equipment to thinly section biological tissues.The sectioned tissue must be of good quality not showing cutting tracks or so-called artefacts.The quality of these sections is dependent on the blade wear,which is related to the hardness of the tissue sample,cutting angle and cutting speed.A test rig has been designed and manufactured to allow these parameters to be controlled.This has allowed for the blade wear to be analysed and quantified,and this has been completed for both ultrasonically assisted and conventional cutting.The obtained results showed a 25.2%decrease in average blade roughness after 38 cuts when using the ultrasonically assisted cutting regime.The data also showed no adverse effect on the quality of the slides produced when using this cutting methodology.Finally,the cutting force measured for both cutting regimes showed that ultrasonically assisted cutting required less force compared to conventional cutting.With the reduction of surface roughness and force,it is possible to state that ultrasonically assisted cutting reduces the wear of the blade,thereby increasing the life of the blades.An increase of just 10%in blade life would yield a cost saving of approximately 25%thereby reducing the environmental and financial impact of microtomy.

An investigation into intermittent electrification strategies and an analysis of resulting CO_(2) emissions using a high-fidelity train model

A near-term strategy to reduce emissions from rail vehicles,as a path to full electrification for maximal decarbonisation,is to partially electrify a route,with the remainder of the route requiring an additional self-powered traction option.These rail vehicles are usually powered by a diesel engine when not operating on electrified track and are referred to as bi-mode vehicles.This paper analyses the benefits of discontinuous electrification compared to continuous electrification using the CO_(2)estimates from a validated high-fidelity bi-mode(diesel-electric)rail vehicle model.This analysis shows that 50%discontinuous electrification provides a maximum of 54%reduction in operational CO_(2)emissions when compared to the same length of continuously electrified track.The highest emissions savings occurred when leaving train stations where vehicles must accelerate quickly to line speed.These results were used to develop a linear regression model for fast estimation of CO_(2)emissions from diesel running and electrification benefits.This model was able to estimate the CO_(2)emissions from a route to within 10%of that given by the high-fidelity model.Finally,additional considerations such as cost and the embodied CO_(2)in electrification infrastructure were analysed to provide a comparison between continuous and discontinuous electrification.Discontinuous electrification can cost up to 56%less per reduction in lifetime emissions than continuous electrification and can save up to 2.3 times more lifetime CO_(2)per distance electrified.

Investigation of thermochemical process of coal particle packed bed reactions for the development of UCG

In this study,a packed bed reactor was developed to investigate the gasification process of coal particles.The effects of coal particle size and heater temperature of reactor were examined to identify the thermochemical processes through the packed bed.Three different coal samples with varying size,named as A,B,and C,are used,and the experimental results show that the packed bed with smaller coal size has higher temperature,reaching 624°C,582°C,and 569°C for coal A,B,and C,respectively.In the case of CO formation,the smaller particle size has greater products in the unit of mole fraction over the area of generation.However,the variation in the porosity of the packed bed due to different coal particle sizes affects the reactions through the oxygen access.Consequently,the CO formation is least from the coal packed bed formed by the smallest particle size A.A second test with the temperature variations shows that the higher heater temperature promotes the chemical reactions,resulting in the increased gas products.The findings indicate the important role of coal seam porosity in underground coal gasification application,as well as temperature to promote the syngas productions.

A Series Solution for Three-Dimensional Navier-Stokes Equations of Flow near an Infinite Rotating Disk

In this paper, homotopy analysis method (HAM) and Padé approximant will be considered for finding analytical solution of three-dimensional viscous flow near an infinite rotating disk which is a well-known classical problem in fluid mechanics. The solution is compared to the numerical (fourth-order Runge-Kutta) solution and the convergence of the obtained series solution is carefully analyzed. The results illustrate that HAM-Padé is an appropriate method in solving the systems of nonlinear equations.

Thermal Fatigue Life Estimation and Fracture Mechanics Studies of Multilayered MEMS Structures Using a Sub-Domain Approach

This paper is concerned with the application of a Physics of Failure (PoF) methodology to assessing the reliability of Micro-Electro-Mechanical-System (MEMS) switches. Numerical simulations, based on the finite element method (FEM) using a sub-domain approach, were performed to examine the damage onset (e.g. yielding) due to temperature variations and to simulated the crack propagation different kind of loading conditions and, in particular, thermal fatigue. In this work remeshing techniques were employed in order to understand the evolution of initial flaws due, for instance, to manufacturing processes or originated after thermal fatigue.

A Broad Range Triboelectric Stiffness Sensor for Variable Inclusions Recognition

With the development of artificial intelligence,stiffness sensors are extensively utilized in various fields,and their integration with robots for automated palpation has gained significant attention.This study presents a broad range self-powered stiffness sensor based on the triboelectric nanogenerator(Stiff-TENG)for variable inclusions in soft objects detection.The Stiff-TENG employs a stacked structure comprising an indium tin oxide film,an elastic sponge,a fluorinated ethylene propylene film with a conductive ink electrode,and two acrylic pieces with a shielding layer.Through the decoupling method,the Stiff-TENG achieves stiffness detection of objects within 1.0 s.The output performance and characteristics of the TENG for different stiffness objects under 4 mm displacement are analyzed.The Stiff-TENG is successfully used to detect the heterogeneous stiffness structures,enabling effective recognition of variable inclusions in soft object,reaching a recognition accuracy of 99.7%.Furthermore,its adaptability makes it well-suited for the detection of pathological conditions within the human body,as pathological tissues often exhibit changes in the stiffness of internal organs.This research highlights the innovative applications of TENG and thereby showcases its immense potential in healthcare applications such as palpation which assesses pathological conditions based on organ stiffness.

The Interplay between Artificial Intelligence and Fog Radio Access Networks

The interplay between artificial intelligence(AI) and fog radio access networks(F-RANs) is investigated in this work from two perspectives: how F-RANs enable hierarchical AI to be deployed in wireless networks and how AI makes F-RANs smarter to better serve mobile devices. Due to the heterogeneity of processing capability, the cloud, fog, and device layers in F-RANs provide hierarchical intelligence via centralized, distributed, and federated learning. In addition, cross-layer learning is also introduced to further reduce the demand for the memory size of the mobile devices. On the other hand, AI provides F-RANs with technologies and methods to deal with massive data and make smarter decisions. Specifically, machine learning tools such as deep neural networks are introduced for data processing, while reinforcement learning(RL) algorithms are adopted for network optimization and decisions. Then, two examples of AI-based applications in F-RANs, i.e., health monitoring and intelligent transportation systems, are presented, followed by a case study of an RL-based caching application in the presence of spatio-temporal unknown content popularity to showcase the potential of applying AI to F-RANs.

Coordinated Control Architecture for Motion Management in ADAS Systems

Advanced driver assistance systems(ADAS) seek to provide drivers and passengers of automotive vehicles increased safety and comfort. Original equipment manufacturers are integrating and developing systems for distance keeping, lane keeping and changing and other functionalities. The modern automobile is a complex system of systems. How the functionalities of advanced driver assistance are implemented and coordinated across the systems of the vehicle is generally not made available to the wider research community by the developers and manufactures. This paper seeks to begin filling this gap by assembling open source physics models of the vehicle dynamics and ADAS command models. Additionally, in order to facilitate ADAS development and testing without having access to the details of ADAS, a coordinated control architecture for motion management is also proposed for distributing ADAS motion control commands over vehicle systems. The architecture is demonstrated in a case study where motion is coordinated between the steering and the braking systems, which are typically used only for a single functionality. The integrated vehicle and system dynamics using the coordinated control architecture are simulated for various driving tasks. It is seen that improved trajectory following can be achieved by the proposed coordinated control architecture. The models, simulations and control architecture are made available for open access.

Efficient Virtual Network Embedding Algorithm Based on Restrictive Selection and Optimization Theory Approach

Network virtualization(NV) is widely considered as a key component of the future network and promises to allow multiple virtual networks(VNs) with different protocols to coexist on a shared substrate network(SN). One main challenge in NV is virtual network embedding(VNE). VNE is a NPhard problem. Previous VNE algorithms in the literature are mostly heuristic, while the remaining algorithms are exact. Heuristic algorithms aim to find a feasible embedding of each VN, not optimal or sub-optimal, in polynomial time. Though presenting the optimal or sub-optimal embedding per VN, exact algorithms are too time-consuming in smallscaled networks, not to mention moderately sized networks. To make a trade-off between the heuristic and the exact, this paper presents an effective algorithm, labeled as VNE-RSOT(Restrictive Selection and Optimization Theory), to solve the VNE problem. The VNERSOT can embed virtual nodes and links per VN simultaneously. The restrictive selection contributes to selecting candidate substrate nodes and paths and largely cuts down on the number of integer variables, used in the following optimization theory approach. The VNE-RSOT fights to minimize substrate resource consumption and accommodates more VNs. To highlight the efficiency of VNERSOT, a simulation against typical and stateof-art heuristic algorithms and a pure exact algorithm is made. Numerical results reveal that virtual network request(VNR) acceptance ratio of VNE-RSOT is, at least, 10% higher than the best-behaved heuristic. Other metrics, such as the execution time, are also plotted to emphasize and highlight the efficiency of VNE-RSOT.

In vitro calcification studies on bioprosthetic and decellularized heart valves under quasi-physiological flow conditions

The lifespan of biological heart valve prostheses available in the market is limited due to structural alterations caused by calcium phosphate deposits formed from blood plasma in contact with the tissues.The objective of this work is to present a comparative methodology for the investigation of the formation of calcium phosphate deposits on bioprosthetic and tissue-engineered scaffolds in vitro and the influence of mechanical forces on tissue mineralization.Based on earlier investigations on biological mineralization at constant supersaturation,a circulatory loop simulating dynamic blood flow and physiological pressure conditions was developed.The system was appropriately adapted to evaluate the calcification potential of decellularized(DCV)and glutaraldehyde-fixed(GAV)porcine aortic valves.Results indicated that DCV calcified at higher,statistically nonsignificant,rates in comparison with GAV.This difference was attributed to the tissue surface modifications and cell debris leftovers from the decellularization process.Morphological analysis of the solids deposited after 20 h by scanning electron microscopy in combination with chemical microanalysis electron-dispersive spectroscopy identified the solid formed as octacalcium phosphate(Ca8(PO4)6H2·5H2O,OCP).OCP crystallites were preferentially deposited in high mechanical stress areas of the test tissues.Moreover,GAV tissues developed a significant transvalvular pressure gradient increase past 36 h with a calcium deposition distribution similar to the one found in explanted prostheses.In conclusion,the presented in vitro circulatory model serves as a valuable prescreening methodology for the investigation of the calcification process of bioprosthetic and tissue-engineered valves under physiological mechanical load.

Postponement in New Product Introduction

Agility has now been a main research topic in the l it erature. There is much written on agility mainly focusing on manufacturing p rocess and strategic processes. However, we argue that new product introduction should call for agility as well due to uncertainty about technological advances and customers’ demand. A technological superiority alone may not guarantee succe ss for new product introduction. We focus on the role of postponement for two ma in processes in new product introduction: new product development and new produc t launch. Postponement enables designers to incorporate the most current technol ogical advances and user needs as these co-evolve with the development process. Postponement can also significantly reduce risk associated with new product lau nch. It thus can be expected that postponement will be increasingly employed in new product introduction.

Effect of biophysical interventions on balance and postural control in patients with ankle instability:A systematic review

Ankle sprains have been one of the most prevalent injuries in active populations.This study aims to summarize the evidence of the effect of the biophysical techniques on balance and postural control in patients with ankle instability,and provide an overview of the application of biophysical interventions in patients with chronic ankle instability(CAI).A systematic search was conducted to include ten articles from 1989 to 2022 in this study.These articles were classified into two categories of balance and postural control.The authors identified a total of 1267 papers and decided to include 10 of them in the systematic review.The Star Excursion Balance Test(SEBT)technique can help clinicians identify balance deficits and postural control,including a comprehensive evaluation of joint stability,strength,and sensorimotor function that would be undetected with single-leg stance static tests.These ten studies involved 481 participants with a mean age of 25.5±6.3 years.The mean duration time of the interventions was 5.4±2.4 weeks and the mean session training duration time was 36.7±17.0 min.The Kinesio taping(KT)and both the soft and semi-rigid orthosis brace may be productive in enhancing dynamic balance assessed by Star Excursion Balance Test.The use of SG may improve perceived ankle instability and dynamic postural control(i.e.,anterior reach during SEBT)of patients with CAI.Regarding the intervention group,no homogeneity results in uncertainties about which techniques of intervention affect balance and postural control.

A high-power electromagnetic source for disabling improvised explosive devices

Ultra-wideband(UWB)microwave sources driven by specialised pulsed power generators have experienced a considerable development in the last decade due to their wide domain of new applications such as defence or counter-terrorism activity.The authors present the main findings of a research dedicated to the development of a pulsed power-driven electromagnetic field source for disabling improvised explosive devices(IED).The pulsed power generator driving the source is a 13-stage compact Marx producing voltage pulses reaching an amplitude of 0.5 MV,with a pulse repetition frequency(PRF)of up to 100 Hz.The generator is coupled to a bipolar pulse forming line,providing bipolar pulses with a dV/dt of around 1.6 MV/ns.This pulsed power system feeds an array composed of 16 Koshelev-type UWB antennas through an impedance matching transformer.The resulting electromagnetic source is capable to produce pulsed electric fields(PEFs)having a figure-of-merit(FOM)of 1 MV.First,practical experiments were carried out to study the effects of the PEFs on targets.The targets used in the present study are M2B type flashbulbs,known to have the same susceptibility as the US army M6 detonator.Different configurations of wires(shielded,twisted,etc)with different lengths were used in connecting items inside these targets.The tests were performed by placing the flashbulbs at different distances to determine the essential parameters(i.e.,amplitude,duration,and frequency range)of the PEFs required to trigger them.An overview of the experimental campaign and the main findings are also presented followed by conclusions.

SPH-BEM simulation of underwater explosion and bubble dynamics near rigid wall

A process of underwater explosion of a charge near a rigid wall includes three main stages: charge detonation, bubble pulsation and jet formation. A smoothed particle hydrodynamics(SPH) method has natural advantages in solving problems with large deformations and is suitable for simulation of processes of charge detonation and jet formation. On the other hand, a boundary element method(BEM) is highly efficient for modelling of the bubble pulsation process. In this paper, a hybrid algorithm, fully utilizing advantages of both SPH and BEM, was applied to simulate the entire process of free and near-field underwater explosions. First, a numerical model of the free-field underwater explosion was developed, and the entire explosion process–from the charge detonation to the jet formation–was analysed. Second, the obtained numerical results were compared with the original experimental data in order to verify the validity of the presented method. Third, a SPH model of underwater explosion for a column charge near a rigid wall was developed to simulate the detonation process. The results for propagation of a shock wave are in good accordance with the physical observations. After that, the SPH results were employed as initial conditions for the BEM to simulate the bubble pulsation. The obtained numerical results show that the bubble expanded at first and then shrunk due to a differences of pressure levels inside and outside it. Here, a good agreement between the numerical and experimental results for the shapes, the maximum radius and the movement of the bubble proved the effectiveness of the developed numerical model. Finally, the BEM results for a stage when an initial jet was formed were used as initial conditions for the SPH method to simulate the process of jet formation and its impact on the rigid wall. The numerical results agreed well with the experimental data, verifying the feasibility and suitability of the hybrid algorithm. Besides, the results show that, due to the effect of the Bjerknes force, a jet with a high speed was formed that may cause local damage to underwater structures.

Surface engineering and the application of laser-based processes to stents-A review of the latest development

Late in-stent thrombus and restenosis still represent two major challenges in stents’design.Surface treatment of stent is attracting attention due to the increasing importance of stenting intervention for coronary artery diseases.Several surface engineering techniques have been utilised to improve the biological response in vivo on a wide range of biomedical devices.As a tailorable,precise,and ultra-fast process,laser surface engineering offers the potential to treat stent materials and fabricate various 3D textures,including grooves,pillars,nanowires,porous and freeform structures,while also modifying surface chemistry through nitridation,oxidation and coatings.Laser-based processes can reduce the biodegradable materials’degradation rate,offering many advantages to improve stents’performance,such as increased endothelialisation rate,prohibition of SMC proliferation,reduced platelet adhesion and controlled corrosion and degradation.Nowadays,adequate research has been conducted on laser surface texturing and surface chemistry modification.Laser texturing on commercial stents has been also investigated and a promotion of performance of laser-textured stents has been proved.In this critical review,the influence of surface texture and surface chemistry on stents performance is firstly reviewed to understand the surface characteristics of stents required to facilitate cellular response.This is followed by the explicit illustration of laser surface engineering of stents and/or related materials.Laser induced periodic surface structure(LIPSS)on stent materials is then explored,and finally the application of laser surface modification techniques on latest generation of stent devices is highlighted to provide future trends and research direction on laser surface engineering of stents.