Adhesion Conditions Research Articles

A 3D physical model predicting favorable bacteria adhesion

Predicting the initial steps of bacterial biofilm formation remains a significant challenge accross various fields, such as medical and industrial ones. Here we present a straightforward 3D theoretical model based on thermodynamic rules to assess the early stages of biofilm formation on different material surfaces. This model relying also on morphological aspects of bacteria, we used Atomic Force Microscopy images of two Gram negative bacteria, Pseudomonas fluorescens and Escherichia coli to determine their dimensions and geometries as single cells or in aggregated states. Algorithms developed for our modeling and numerical simulations generated a dataset of energetic minimized states, depending on the substrate. The model was applied to substrates widely used for bacteria immobilization in imaging applications. The results show that the different minimum energy values, depending of the substrate, can be correlated with the bacterial adhesion state, representing a potential tool for evaluating the early stages of biofilm formation on various surfaces.

Efficacy and safety of purified starch for adhesion prevention in colorectal surgery

BackgroundAdhesions within the abdominal cavity develop in as many as 90 % of individuals following abdominal surgery. However, the true adhesive condition of patients can only be ascertained during the second surgery. MethodsWe conducted a prospective, non-randomized study to assess the anti-adhesion properties of purified starch in patients who had undergone colorectal surgery in the past and then needed a subsequent surgical intervention. Adhesion scores have been prospectively recorded in operation notes since January 2020 when patients underwent a second surgery. Patients who had received purified starch during their initial surgery constituted the purified starch group, while those who had not received anti-adhesion medical materials were the control group. The main objectives of the study were to evaluate the extent and severity of adhesions as primary outcomes, while secondary outcomes included measuring blood loss, operation time, and postoperative complications. ResultsWe analyzed the data of 101 patients, with 61 in the purified starch group and 40 in the control group. In multivariate analysis, adhesion severity (Odds ratio, 0.20, 95 % confidence interval 0.08–0.54, P < 0.01) and adhesion area scores (Odds ratio, 0.13, 95 % confidence interval 0.04–0.45, P < 0.01) were significantly lower in the purified starch group than in the control group. There was no significant difference in operation times, blood loss, and postoperative complications between the two groups. ConclusionPurified starch is a safe and effective anti-adhesion material that can significantly reduce the severity and extent of adhesion after colorectal surgery.

Research on launching, water exiting, and river crossing of an amphibious vehicle

The main focus of this paper is the amphibious vehicle's water-land trans-media capability, specifically its ability to efficiently carry out transportation tasks in rivers and nearshore areas. This capability relies on three key processes: launching, water exiting, and river crossing. To study these processes, hydrodynamic numerical simulations are conducted. The Reynolds-averaged Navier–Stokes) equation, simplified terra mechanics model, and body force method are adopted to analyze the trans-media and self-propulsion processes. Results indicate that the optimal launching speed is around 15 km/h, with a stable trim and heave, and a launching angle range of 15°–25° for insubmersibility and stability. Furthermore, high-speed water exiting enhances insubmersibility and imposes lower requirements on road adhesion conditions, outperforming low-speed water exiting. In terms of self-propelled river crossing, higher heading angles and faster river currents improve hydrodynamic lift, with the fastest crossing achieved at a 10° heading angle for a current speed of 2.5 m/s and a forward speed of 30 km/h.

Effect of Aging and Different Surface Treatments on Repair Bond Strength of Hybrid Resin Composites

Background: With the trend for minimally invasive dentistry and the rapid evolution of composite resin materials, repair of defective composite resin restorations is a popular choice rather than replacement of the restoration. The durability of the bond between the old and repaired composite restoration is important for a successful outcome. Objective: To evaluate the immediate and delayed shear bond strength of two types of repaired hybrid resin composites using different chemical and mechanical surface treatments. Methods: Two types of hybrid resin composites, micro-hybrid resin composite and nanohybrid resin composite, were used to prepare 288 pre-polymerized resin composite specimens. After polymerization, repair was done after 24 hours and 6 months. Each hybrid resin composite group was divided into 3 groups according to surface treatment used to repair the substrate: group 1: no surface treatment, group 2: treated by medium abrasive stone, and group 3: treated by fine abrasive stone. Each group was further subdivided into 3 subgroups according to different agents used for repair: group 1: Silane, group 2: Universal adhesive, and group 3: Silane + adhesive. Shear bond strengths of the repaired specimens were measured using a Universal testing machine. Failure modes were evaluated under a stereomicroscope. Results: Different chemical and mechanical surface treatments had a significant effect on the shear bond strength values of all groups (p ≤ 0.05). The highest mean shear bond strength values were found in nano-hybrid composites immediately repaired by silane after treatment by a medium abrasive stone while the lowest mean shear bond strength values were found in micro-hybrid composites with delayed repair and no surface treatment. Conclusion: Diamond burs using silane with adhesive improved the repair bond strength of the tested hybrid composites. In composite repair, using abrasive mechanical pretreatment followed by adhesive conditioning is crucial for the success of the repair restoration.

Smart insect monitoring based on YOLOV5 case study: Mediterranean fruit fly Ceratitis capitata and Peach fruit fly Bactrocera zonata

The agricultural sector in Egypt is adversely affected by factors such as inadequate soil fertility and environmental hazards such as pestilence and diseases. The implementation of early pest prediction techniques has the potential to enhance agricultural yield. Bactrocera zonata and Ceratitis capitata, known as peach fruit fly and Mediterranean fruit fly, respectively, are the predominant pests that cause significant damage to fruits on a global scale. The present study proposes a deep learning-based approach for the detection and quantification of pests. The proposed approach entails the retrieval of data pertaining to the adhesive trap condition, followed by its examination and presentation through a mobile application. The YOLOV5 model has been implemented for the purpose of pest classification, localization, and quantification. In order to address the issue of a restricted dataset, a hybrid technique of transfer learning and data augmentation (copy and paste) was employed. The proposed approach offers an intelligent real time pest detection, thereby facilitating the prediction of treatment options. An application for smartphones has been developed to aid farmers and agricultural professionals in the management and treatment of pests. The proposed approach has the potential to aid farmers in identifying the existence of pests, thereby diminishing the duration and resources needed for farm inspection. As per the results of the conducted experiments, the proposed approach demonstrates a noteworthy increase in performance. The weighted average accuracy reaches 84%, while precision (P), mean average precision (mAP), and F1-score show enhancements of up to 15%, 18%, and 7% respectively.

Potent gene delivery from fluorinated poly(β-amino ester) in adhesive and suspension difficult-to-transfect cells for apoptosis and ferroptosis

Tremendous efforts have been made to improve polymeric property in gene delivery performances, especially when obstacle of transferring gene construct into difficult-to-transfect cells occurs. Innovations in the area of fluorination and fluorinated compounds with biomedical potential in medicinal chemistry are believed to assist in the development of new therapeutics. Fluorine modified polymers have shown to navigate the gene transfection cellular barriers and promoted the transfection outcomes. Gene transfer into some liver cancer cells and human leukemia cells has always been a challenge. Here, by facile incorporation of a fluorine containing amine monomer, 1H,1H-undecafluorohexylamine, fluorinated poly(β-amino ester) (FPAE) was synthesized to significantly improve the transfection performance, achieving high transfection efficiency of 87% and 55% in two representative difficult-to-transfect cells, HepG2 and Molt-4, which were cultured in adhesive and suspension condition, respectively. However, the potency of Lipofectamine 3000 was very limited. More importantly, functional studies revealed that FPAE can dramatically outperform Lipofectamine 3000 in delivering Bcl-xL and PKCβII to either provide the protection against apoptosis or promote the ferroptosis in HepG2 cells. This work facilitates gene therapies by overcoming biological barriers for targeting difficult-to-transfect cells and disease models when medically necessary.

Interface interaction between high viscosity asphalt and aggregate: A multi-scale study based on experiments and molecular dynamics simulation

The pull-off strength, boiling peeling ratio, adhesion work, stripping work, interaction energy, nanoindentation resistance force, and hydrogen bond distribution were analyzed based on laboratory tests and molecular dynamics simulation. The interface interaction between the original, aged, or regenerated high-viscosity asphalt (HVA) and the acid or alkali aggregate component in the aqueous or anhydrous environment was clarified from multi-scales of macro, micro, and nano scales. The results show that the pulling strength has an obvious positive correlation with the interfacial adhesion work, which can evaluate the interfacial adhesion state with water. The boiling peeling ratio has an obvious positive correlation with the interface stripping work, which can evaluate the interfacial adhesion state without water. The ratio of adhesion work to stripping work can characterize the interface water-stripping resistance. In nanoindentation simulation, the vertical resistance force of the indenter characterizes the interaction between HVA and the aggregate indenter. The interfacial adhesion state deteriorates with the deepening of HVA aging. Further addition of a high viscosity modifier (HVM) in the regenerated HVA effectively restores the interfacial adhesion state. The higher temperature causes worse interfacial adhesion, and the hydrogen bond ratio, adhesion, and water-stripping resistance of the interface between the HVA and alkaline aggregate components are much better than those between the HVA and acid aggregate components. Van der Waals force plays a leading role in interfacial adhesion. With the deepening of aging, the oxygen-containing functional groups such as carbonyl and sulfoxide in HVA increase, in which it is easy for oxygen atoms to form hydrogen bonds with water, so the water-stripping resistance of the interface decreases.

Anoikis resistance and immune escape mediated by Epstein-Barr virus-encoded latent membrane protein 1-induced stabilization of PGC-1α promotes invasion and metastasis of nasopharyngeal carcinoma

BackgroundEpstein-Barr virus (EBV) is the first discovered human tumor virus that is associated with a variety of malignancies of both lymphoid and epithelial origin including nasopharyngeal carcinoma (NPC). The EBV-encoded latent membrane protein 1 (LMP1) has been well-defined as a potent oncogenic protein, which is intimately correlated with NPC pathogenesis. Anoikis is considered to be a physiological barrier to metastasis, and avoiding anoikis is a major hallmark of metastasis. However, the role of LMP1 in anoikis-resistance and metastasis of NPC has not been fully identified.MethodsTrypan blue staining, colony formation assay, flow cytometry, and TUNEL staining, as well as the detection of apoptosis and anoikis resistance‐related markers was applied to evaluate the anoikis-resistant capability of NPC cells cultured in ultra-low adhesion condition. Co-immunoprecipitation (Co-IP) experiment was performed to determine the interaction among LMP1, PRMT1 and PGC-1α. Ex vivo ubiquitination assay was used to detect the ubiquitination level of PGC-1α. Anoikis- resistant LMP1-positive NPC cell lines were established and applied for the xenograft and metastatic animal experiments.ResultsOur current findings reveal the role of LMP1-stabilized peroxisome proliferator activated receptor coactivator-1a (PGC-1α) in anoikis resistance and immune escape to support the invasion and metastasis of NPC. Mechanistically, LMP1 enhances PGC-1α protein stability by promoting the interaction between arginine methyltransferase 1 (PRMT1) and PGC-1α to elevate the methylation modification of PGC-1α, thus endowing NPC cells with anoikis-resistance. Meanwhile, PGC-1α mediates the immune escape induced by LMP1 by coactivating with STAT3 to transcriptionally up-regulate PD-L1 expression.ConclusionOur work provides insights into how virus-encoded proteins recruit and interact with host regulatory elements to facilitate the malignant progression of NPC. Therefore, targeting PGC-1α or PRMT1-PGC-1α interaction might be exploited for therapeutic gain for EBV-associated malignancies.

Oil structuring from porous starch to powdered oil: Role of multi-scale structure in the oil adsorption and distribution

Oil structuring from porous starch is a potential alternative for the industrial production of powdered oil, but their relationship between starch multi-scale structure and oil adsorption characteristics was not clear. This study compared the role of multi-scale structure of porous starch (PS) prepared by normal and waxy maize starch in the oil adsorption. Waxy maize porous starch exhibited higher oil adsorption capacity (32.43 %–98.71 %) and more oil distributed on the surface of granules than normal maize porous starch, resulting from the more pores, larger specific surface area (1.01–1.53 m2/g), and pore size (8.45–9.32 nm). The enzymolysis time of native starch dominated oil distribution, leading to different granule adhesion and aggregation state. Pearson correlation analysis further showed oil adsorption capacity was negatively correlated with particle size, but positively correlated with enzymolysis rate and specific surface area of PS. The formation of powdered oil was mainly through the physical adsorption, including surface adsorption and pore adsorption. These findings could provide a promising route for the preparation of powdered oil with controlled multi-scale structure of PS.

On-line learning applied to spiking neural network for antilock braking systems

Computationally replicating the behaviour of the cerebral cortex to perform the control tasks of daily life in a human being is a challenge today. First, it is necessary to know the structure and connections between the elements of the neural network that perform movement control. Next, a mathematical neural model that adequately resembles biological neurons has to be developed. Finally, a suitable learning model that allows adapting neural network response to changing conditions in the environment is also required. Spiking Neural Networks (SNN) are currently the closest approximation to biological neural networks. SNNs make use of temporal spike trains to deal with inputs and outputs, thus allowing a faster and more complex computation. In this paper, a controller based on an SNN is proposed to perform the control of an anti-lock braking system (ABS) in vehicles. To this end, two neural networks are used to regulate the braking force. The first one is devoted to estimating the optimal slip while the second one is in charge of setting the optimal braking pressure. The latter resembles biological reflex arcs to ensure stability during operation. This neural structure is used to control the fast regulation cycles that occur during ABS operation. Furthermore, an algorithm has been developed to train the network while driving. On-line learning is proposed to update the response of the controller. Hence, to cope with real conditions, a control algorithm based on neural networks that learn by making use of neural plasticity, similar to what occurs in biological systems, has been implemented. Neural connections are modulated using Spike-Timing-Dependent Plasticity (STDP) by means of a supervised learning structure using the slip error as input. Road-type detection has been included in the same neural structure. To validate and to evaluate the performance of the proposed algorithm, simulations as well as experiments in a real vehicle were carried out. The algorithm proved to be able to adapt to changes in adhesion conditions rapidly. This way, the capability of spiking neural networks to perform the full control logic of the ABS has been verified.

Femtosecond Laser Direct Writing of Gecko-Inspired Switchable Adhesion Interfaces on a Flexible Substrate.

Biomimetic switchable adhesion interfaces (BSAIs) with dynamic adhesion states have demonstrated significant advantages in micro-manipulation and bio-detection. Among them, gecko-inspired adhesives have garnered considerable attention due to their exceptional adaptability to extreme environments. However, their high adhesion strength poses challenges in achieving flexible control. Herein, we propose an elegant and efficient approach by fabricating three-dimensional mushroom-shaped polydimethylsiloxane (PDMS) micropillars on a flexible PDMS substrate to mimic the bending and stretching of gecko footpads. The fabrication process that employs two-photon polymerization ensures high spatial resolution, resulting in micropillars with exquisite structures and ultra-smooth surfaces, even for tip/stem ratios exceeding 2 (a critical factor for maintaining adhesion strength). Furthermore, these adhesive structures display outstanding resilience, enduring 175% deformation and severe bending without collapse, ascribing to the excellent compatibility of the micropillar's composition and physical properties with the substrate. Our BSAIs can achieve highly controllable adhesion force and rapid manipulation of liquid droplets through mechanical bending and stretching of the PDMS substrate. By adjusting the spacing between the micropillars, precise control of adhesion strength is achieved. These intriguing properties make them promising candidates for various applications in the fields of microfluidics, micro-assembly, flexible electronics, and beyond.

Research on train braking model by improved Polach model considering wheel‐rail adhesion characteristics

AbstractTo study the braking process of the train under different adhesion conditions, this paper takes the braking system of a single rail vehicle as the research object. The author establishes a corresponding co‐simulation platform based on MATLAB/Simulink and AMESim, including the sub‐models of braking control, vehicle brake longitudinal dynamics and air brake unit. Considering the cleaning effect caused by large sliding, the author builds a suitable adhesion model for different adhesion conditions based on the improved Polach model, which is the input of the vehicle braking longitudinal dynamics sub‐model. Based on the finite state machine, the anti‐skid control algorithm of the train is constructed as the core of the brake control sub‐model, which can judge the motion state of the wheelset, and control the stage release and hold of the brake cylinder pressure. According to the International Standard EN15595 and the actual operating parameters of a certain type of train, the braking process of the train under dry and wet rail conditions is simulated on the platform. The validity of the model is verified, which provides a reliable method for future research on the braking process.

Aphid-Inspired and Thermally-Actuated Soft Gripper Using 3D Printing Technology.

Herein, a thermo-actuated aphid-inspired dry adhesive (TADA) that offers tunable and reversible adhesion isreported. It is easily fabricated through 3D printing using a polylactic acid (PLA) filament and silicone elastomer, avoiding the use of unfavorable methods for micro- and nanofabrication and unwanted particles for actuation. The tunable adhesive system mimics aphid biology to achieve adhesion switchability. Switching between adhesion states is enabled by the thermo-actuated PLA, which has shape memory properties. Additionally, silicone elastomer enables adherence to flat substrates such as glass, silicon wafers, and acrylic plates. The detachment time of the TADA can be controlled by changing the printing layer height, which is a 3D-printing parameter that results in a short detachment time when the printing layer height is small. The adhesion strength ismeasured by applying different preloads and varying the size of the adhesive area. The reversibility between the adhesion-on and adhesion-off states, revealing good repeatability with similar adhesion strengths isalso demonstrated. The TADA has potential applications in transferring silicon wafers. In addition, it can be printed to fit a flat plate of any shape, enabling it to grip the plate stably.

A review of safety test methods for new car assessment program in Southeast Asian countries

Abstract Vehicles with advanced active safety technology can decrease the significant traffic accidents that can lead to death. This active safety frontier falls under primary safety in the European New Car Assessment Program (Euro NCAP) 2025 Roadmap, which has become one of the overall safety rating initiatives toward safer vehicles. Some frontier active safety technologies will be assessed, including autonomous emergency steering (AES) and autonomous emergency braking (AEB). However, the New Car Assessment Program in Southeast Asian Countries (ASEAN NCAP) only focuses on AEB technologies. Hence, this work discusses the existing papers on AES assessment, AES demand, AES control, AES system with Artificial intelligence, and AES testing methodology. Three articles from the industry discussing the AES function in passenger automobiles were found as a result of an article search using the Google search platform. Other terminologies like emergency steering control and emergency steering assist are used instead of AES. However, the principle remains the same. The three categories have been recognized from all of the document results: road adhesion condition, driver condition identification, and rear-end collision. However, only the rear-end collision situations are further investigated in this work to recognize the currently available approach used by previous studies. According to the review findings, just a few AEB intervention systems are now accessible, while AES technology is still in its early phases. That might explain the lack of exact evaluations and effective remedies. As a result, this research aims to offer evidence supporting the proposed methodology for assessing and evaluating AES in the ASEAN NCAP rating scheme. Besides that, this study can also help industries such as automakers and automotive vendors leverage the guidelines to fit the AES in their future models.

Effect of thickness on the behavior of aggregate-asphalt-aggregate film subjected to dynamic shearing and uniaxial tension

Although the asphalt-aggregate interface and its film thickness present important effect on performance of asphalt mixtures, there are no effective methods to accurately evaluate those factors. This study focuses on the effect of aggregate-asphalt-aggregate thickness on the shearing and tension mechanical properties of the asphalt-aggregate by using aggregate developed Dynamic Shearing Rheometer (DSR). Utilizing microscopic techniques to observe the surface morphology of different aggregates and the adhesion state of asphalt-aggregate micro-interface zone, and then carried out the dynamic shear rheological test and uniaxial tension test analysis of aggregate-asphalt-aggregate system under different interlayer thickness and different aggregate adhesion conditions. Results indicate that the developed DSR using aggregate plates is a helpful device to simulate the interface in asphalt mixtures. Differences in microscopic morphology and chemical adhesion have a significant impact on the shearing and tension behavior of aggregate-asphalt-aggregate system. The influence of microscopic interaction between aggregate and asphalt on the mechanical behavior of asphalt is dependent on temperature, frequency, interlayer thickness, and loading pattern. The thickness of the interlayer shows different modes subjected to loading, which is reflected as that film thinning means modulus softening during shearing loading and film thinning means modulus strengthening during tension loading.

A cell-electrode interface signal-to-noise ratio model for 3D micro-nano electrode.

3D Micro-nano electrodes (MNE) with the vertical nanopillar array distributed on the surface play an increasingly important role in neural science research. The geometric parameters of the nanopillar array and the cell adhesion state on the nanopillar array are the factors that may affect the MNE recording. However, the quantified relationship between these parameters and the signal-to-noise ratio (SNR) is still unclear. This paper establishes a cell-MNE interface SNR model and obtains the mathematical relationship between the above parameters and SNR. The equivalent electrical circuit and numerical simulation are used to study the sensing performance of the cell-electrode interface. The adhesion state of cells on MNE is quantified as engulfment percentage, and an equivalent cleft width is proposed to describe the signal loss caused by clefts between the cell membrane and the electrode surface. Whether the planar substrate is insulated or not, the SNR of MNE is greater than planar microelectrode (PME) only when the engulfment percentage is greater than a certain value. Under the premise of maximum engulfment percentage, the spacing and height of nanopillars should be minimized, and the radius of the nanopillar should be maximized for better signal quality. The model can clarify the mechanism of improving SNR by nanopillar arrays and provides the theoretical basis for the design of such nanopillar neural electrodes.

Counterintuitive delayed failure of soft adhesive system under shear holding

Soft adhesive structures are widely employed in cutting-edge applications due to their unique mechanical properties. However, the phenomenon of delayed failure resulting from static loading is often overlooked in these scenarios. In particular, the counterintuitive delayed failure of the soft adhesive structure under shear displacement holding, where no additional energy is input into the soft adhesive structure during the macroscopic relaxation process, poses a challenge for comprehension. To address this, this work employs a time-dependent cohesive zone model (CZM) to characterize the viscoelastic behavior of the soft adhesive within the soft adhesive structure during displacement holding. Two adhesive systems, namely the hard adherend bonded to the hard substrate with soft adhesive (HSH) and the soft adherend bonded to the hard substrate with soft adhesive (SSH), were investigated both experimentally and numerically. The adopted CZM was validated through single-lap shear tests on HSH, encompassing single loading, constant force, and displacement holding experiments. Subsequently, the delayed failure of the local soft adhesive in SSH was investigated, and the deformation field of the soft adherend during the holding process was observed experimentally using the particle tracking method. The results reveal that the delayed failure of SSH is attributed to the occurrence of local creep in the soft adhesive at the crack front, despite the evident macroscopic relaxation phenomenon observed during displacement holding. Aiming to eliminate the delayed failure of the soft adhesive structure, the importance of the adherend to adhesive modulus ratio, viscoelastic properties, and loading conditions were discussed to address the delayed failure of the soft adhesive structure. By shedding light on the overlooked aspect of delayed failure in soft adhesive structures, this study presents a novel perspective that extends beyond conventional static loading analyses. The understanding of delayed failure mechanisms provides valuable guidance for enhancing the performance of soft adhesive structures.

Decellularized umbilical cord stroma in tissue engineering and regenerative medicine: a systematic review

Despite great progress in the field of biomaterials for tissue engineering and regenerative medicine, the high requirements placed on artificial matrices (matrices, carriers, scaffolds) are the reason for the ongoing search for natural or synthetic extracellular matrix mimetics. Among such materials, decellularized umbilical cord (UC) stroma appears to be very attractive – it has a high content of hyaluronic acid, cytokines, and growth factors, and there are no ethical restrictions for its production. Decellularized UC stroma has been found to promote cartilage, liver tissue and nerve tissue repair, as well as wound healing. The review critically analyzes and summarizes published data on the ability of decellularized UC stroma to maintain the necessary conditions for adhesion, migration, differentiation and functional activity of adherent cells, thus stimulating the internal (physiological) regenerative potential of tissues. Literature was searched for in the following electronic databases: Medline/PubMed (www/ncbi. nlm.nih.gov/pubmed), Cochrane library (https://www.cochrane.org), and eLIBRARY/Russian Science Citation Index (https://www.elibrary.ru). Inclusion criteria were the presence of biomaterials obtained from decellularized human UC stroma. Exclusion criteria for papers included research objects as decellularized umbilical cord vessels (veins and arteries) and umbilical cord cell cultures. Twenty-five original articles in English and Russian were selected for analysis of the products obtained, their applications, decellularization methods and research results. The review also discusses the prospects for decellularized umbilical cord in medicine.

Adhesion control strategy for trains with driven independently rotating wheels considering active guidance

AbstractThis article presents a torque distribution control strategy for electrical trains equipped with driven independently rotating wheels (DIRW) to realise the coordination of guidance control and adhesion control. For DIRW, active guidance control is required to restore self‐centring ability. Besides, the adhesion condition determines the wheel‐rail tangential force, affecting the realisation of the guidance function. A zero lateral displacement guidance control based on an active disturbance rejection controller and an adhesion control based on optimal adhesion coefficient utilisation are applied. According to the wheel‐rail adhesion state, several torque distribution rules are designed. The primary principle of rule design is to ensure the normal operation of trains, that is, to avoid the occurrence of train idling/sliding. Next, the self‐centring function should be achieved. Finally, the train traction/braking performance should be as close as possible to the requirements of the traction/braking characteristic curve determined by the driver handle instruction. The torque distribution strategy proposed can achieve the traction/braking and guidance function on the adhesion limit. The control performance is verified through MATLAB/Simulink‐SIMPACK co‐simulation.

Aerodynamic stability of vehicle passing through a bridge tower at high speed under crosswind conditions with different road adhesion coefficients

In a complex environment, large bridges will present different adhesion coefficient, often accompanied by large crosswind, which makes the flow field around the vehicle complex and changeable. It is easy to cause unnecessary lane change and sideslip of the vehicle, which will affect the driving stability and lead to serious traffic accidents. Therefore, this paper studies the aerodynamic stability of cars passing through the bridge tower at high speed under different road adhesion and crosswind conditions. The detached-eddy simulation (DES) model was employed and the reliability of the DES model was verified by wind tunnel tests. An overlapping mesh technique was adopted to realize the motion of the vehicle. A multibody dynamic (MBD) model of the vehicle was established, and its robustness was verified. A two-way coupling model was then established based on the aerodynamic and MBD models. Subsequently, the aerodynamic characteristics and dynamic response of the vehicle passing through the bridge tower at a high speed were compared and analyzed using one-way and two-way coupling methods, with road adhesion coefficients of 1.0, 0.6, and 0.4 under crosswind conditions. The results show that the aerodynamic characteristics of the vehicle passing the bridge tower at a low adhesion coefficient under two-way coupling change evidently, and the trajectory and body attitude of the vehicle change significantly. As the adhesion coefficient of the road surface decreases, the vehicle passes through the bridge tower with a large lateral displacement and yaw angle. The maximum lateral force of −1406 N and the maximum yaw moment of 803 N∙m are generated when the car passes through the bridge tower under the two-way coupling with the adhesion coefficient of 0.4. Under two-way coupling, the lateral displacement and yaw angle caused by the bridge deck with an adhesion coefficient of 0.4 are 0.265 m and 0.0205 rad, respectively, which is larger than those of the bridge deck with adhesion coefficients of 1.0 and 0.6. Because the coupling effect of aerodynamic and vehicle motion is not considered in the one-way coupling, the one-way and two-way coupling simulation results differ significantly. The results indicate that it is necessary to use a two-way coupling method to study the aerodynamic stability of vehicles passing through a bridge tower at a high speed under crosswind conditions.