Collision Area Research Articles

Preparation and performance verification of polyvinyl alcohol hydrogel biomimetic coating on the surface of vascular intervention guidewires

During guidewire interventions in intricate blood vessels, friction and collisions between the guidewire and the vessel wall can lead to complications such as vascular damage. This study focuses on the preparation of a lubricating hydrogel as a biomimetic coating on the guidewire surface. Four types of composite hydrogel biomimetic coatings were prepared using polyvinyl alcohol (PVA), dimethyl sulfoxide (DMSO), silane coupling agent (SCA), and glycerol in different ratios. The fundamental properties of the composite hydrogels were initially investigated, including the swelling behavior, mechanical characteristics, friction property, as well as adhesive property. Subsequently, the practical application of the hydrogel biomimetic coatings on guidewires were analyzed through intervention frictional force analysis, friction resisting tests, and collision tests in intricate blood vessels. The experimental results indicate that the hydrogel biomimetic coating, comprising PVA, DMSO, and SCA, exhibited a maximum friction force at least 0.07 N lower than the minimum friction force observed with the uncoated guidewires. Additionally, it significantly shortens the time required for the guidewire to break through collision area in intricate blood vessels, reducing it from 1.8 s to 0.9 s, indicating its superior lubrication performance. This finding offers experimental evidence for enhancing the safety of clinical intervention surgeries.

Collision-Damage Analysis of a Floating Offshore Wind Turbine Considering Ship-Collision Risk

As the number of offshore wind-power installations increases, collision accidents with vessels occur more frequently. This study investigates the risk of collision damage with operating vessels that may occur during the operation of an offshore wind turbine. The floater used in the collision study is a 15 MW UMaine VolturnUS-S (semi-submersible type), and the colliding ships are selected as multi-purpose vessels, service operation vessels, or anchor-handling tug ships based on their operational purpose. Collision analysis is performed using ABAQUS and substantiation is performed via a drop impact test. The collision analyses are conducted by varying the ship velocity, displacement, collision angle, and ship shape. By applying this numerical model, the extent of damage and deformation of the collision area is confirmed. The analysis results show that a vessel with a bulbous bow can cause flooding, depending on the collision conditions. For damage caused by collision, various collision angles must be considered based on the internal stiffener arrangement. Additionally, the floater can be flooded with relatively small collision energy when the colliding vessel has a bulbous bow.

Effect of Single Particle High-Speed Impingement on the Electrochemical Step Characteristics of a Stainless-Steel Surface.

In the process of particle erosion and electrochemical corrosion interaction, the electrolyte flow state change, product film destruction, and matrix structure change caused by particle impact affect the electrochemical corrosion process. Such transient, complex physical and electrochemical changes are difficult to capture because of the short duration of action and the small collision area. The peak, step time, and recovery time in this transient step cycle can indirectly reflect the smoothness and reaction rate of the electrochemical reaction system, and thus characterize the resistance to scouring corrosion coupling damage of metals in liquid-solid two-phase flow. In this study, in order to obtain the electrochemical response at the moment of particle impact, electrochemical monitoring experiments using a specially designed miniature three-electrode system were used to test step-critical values, including step potential, current, and resistance, among others. Meanwhile, an electrochemical step model under particle impact considering boundary layer perturbation was developed. The experimental results reflect the effect law of particle impact velocity and particle size on the peak step and recovery period. Meanwhile, the effect of particle impingement on the electrochemical step of stainless steel in different electrolyte solutions was obtained by comparing the step curves in distilled water and Cl-containing water. The connection between the parameters in the electrochemical step model and in the particle impact, as well as the effect of the variation of these parameters on the surface repassivation process are discussed in this paper. By fitting and modeling the test curves, a new mathematical model of electrochemical step-decay under single-particle impact was obtained, which can be used to characterize the change pattern of electrochemical parameters on the metal surface before and after the impingement.

Airflow collision characteristics of double square column attachment ventilation

In the square column attachment ventilation (S-CAV) mode, the introduction of multiple airflows attached to the column into the horizontal diffusion zone inevitably leads to various “airflow collision” phenomena. However, after the floor-attached airflow collides, the indoor air distribution may deviate from the design goal. In this paper, the layout of the axisymmetric and non-axisymmetric arrangement of double columns is summarized. The airflow collision mechanism and flow characteristics for different column layouts are analyzed via experiments and computational fluid dynamics (CFD) simulations, and a new partition form is proposed to more effectively control the indoor environment. A 1:2 scale model was employed for the velocity verification experiments and flow field visualization. The results indicated that the airflow collision area can be divided into impact, transition, and collision zones with axisymmetric double-column layouts. In the range of 1–3 m/s, any variation in the supply air velocity, irrespective of the occurrence of airflow collision, may be considered negligible with respect to its impact on the attenuation trend of the axial velocities. At the same absolute value of the air supply temperature difference, the cooling condition experiences a 3.1 times greater kinetic energy loss due to collision than does the heating condition. In a nonsymmetric arrangement of two columns, the curve formed by the stagnation point rotates, and the direction of rotation is biased toward the side of the column that is farther away. The findings provide a solid theoretical basis for the engineering application and optimal design of CAV modes.

Study on a 3D Train-Track-Bridge System Dynamic Behavior Subjected to Over-Height Collision Force

Railway bridges are built to allow trains to cross over highways, valleys, or other transportation infrastructure. In recent years, the number of railway bridges subjected to over-height collision forces has increased. These collisions damage the bridge and affect the safety of the running train. In this investigation, first, a 3D GT26 train-track-bridge interaction model was created to study the effects of collision forces applied to the bridge superstructure and not to the bridge piers as a novelty of this research using the finite element analysis. Then, the dynamic responses of the railway bridge due to the GT26 train load and subjected to over-height collision forces were obtained. Finally, the different sensitivity analyses describe that changing the length of the collision area, the bridge span, and the value of collision forces affect the dynamic responses of the bridge in the contact area. The results show that maximum lateral displacement of the concrete girder in case of assuming the GT26 train 3D model plus over-height collision force is 8.88% less than the case in which considering only freight train axle-load and same over-height collision force apply to the bridge superstructure, and its value reduces from 45 mm to 41 mm. The maximum lateral displacement of the bridge deck is reduced by about 71% by increasing the collision area length from 0.2 m to 1.2 m and at the impact area rises about 43.5% by changing collision speed from 48 km/hr to 144 km/hr as collision force from 7753 kN to 13370 kN.

A MODEL FOR SURFACE NANORELIEF FORMATION UNDER GAS CLUSTER ION IRRADIATION

A model for the evolution of surface nanorelief under irradiation with gas cluster ions is proposed. The model is based on consideration of individual collisions of clusters with a surface. The amount of substance sputtered from the collision area and the e ciency of its redeposition onto other surface elements are determined. The performance of the model is shown when compared with experimental data. The stages of smoothing of a harmonic relief are studied. A new measure of the e ectiveness of surface smoothing is proposed.

Differential characteristics of the particles sputtered by gas cluster ions at elevated temperatures. Molecular dynamics simulation

The effect of the target temperature on sputtering by gas cluster ions was investigated using molecular dynamics simulation. The temperature of <111> copper target was set in range from 300 K to 1100 K, and bombarding 10 keV argon clusters had the size from 50 to 500 atoms. Sputter yield was found to increase with the temperature. The increase depended on the cluster size, and its value was much higher than it had been considered previously for nonlinear sputtering. Differential characteristics of the process, such as angular, energy, and time distributions of the sputtered atoms, as well as their initial positions, were obtained to promote understanding of the mechanisms involved. The dynamics of the collision crater size and its shape were described. The concept of temperature inside the collision area was used to explain the results.

Increasing Efficiency and Reliability in Multicast Routing based V2V Communication for Direction-Aware Cooperative Collision Avoidance

Mobile ad hoc networks (MANETs), which are a promising method for the intelligent transportation system, include vehicular ad hoc networks (VANETs) (ITS). Developing reliable and strong cooperative collision avoidance (CCA) strategy to mitigate the growing number of road fatalities each year is one of the main difficulties facing vehicular ad hoc networks (VANETs).A proper and successful routing method aids in the successful expansion of vehicular ad hoc networks. This study explains the architecture, interface layers, safety features, and implementation of a novel priority-based direction-aware collision avoidance system (P-DVCA). It distinguishes our study in the collision area of VANETs by accounting for realistic bi-directional traffic. The scheme begins with the development of dynamic clusters, which is difficult because of the bi-directional diverse traffic and the need to avoid collisions within and between clusters. The target node is sent an early warning message that includes the safe speed and the likelihood of a collision in order to notify it of an impending danger. To determine the least expensive, shortest one with the fewest hops between the source and the endpoint. A crucial problem with VANETs is the transmission of data from a source node to the base station. Cross-layer issues must be solved for a robust and stable collision avoidance programme to function properly in a VANET communication architecture. The results of the simulation show that the suggested scheme significantly outperforms CCM and C-RACCA in terms of cluster stability, fewer collisions, low latency, and low communication overhead. According to the findings, P-DVCA offers stable clustering, minimises network congestion, and lowers communication overhead and latency.

Numerical study of mechanical response of shield tunnel under vehicle collision

Shield tunnels account for an essential part of the urban highway system, which are more likely to encounter terrible traffic accidents during daily operation. There is a risk of collision between the errant vehicle and the shield tunnel when a traffic accident occurs. This paper establishes a refined numerical model of the shield tunnel based on the Wuhan Yangtze River Tunnel and the vehicle numerical model. Considering the four factors (vehicle weight, speed, collision angle, ground reaction coefficient), an orthogonal test scheme designing 9 simulation cases is proposed. During the collision, the dynamic responses (opening and dislocation of segment joints, stress, and plastic damage of shield tunnel lining) are studied. Results show that the anti-collision wall and segment lining are damaged to varying degrees, and bolts and reinforcement bars in the collision area reach their yield strength; meanwhile, segment joints appear to have irreversible opening and dislocation. According to the extremum difference analysis of orthogonal simulation results, vehicle weight and speed are the two leading factors in structural responses, the contribution degree of which is significantly larger than collision angle and ground reaction coefficient in structural responses.

Simulation of collision using Glauber model

This article is going to discuss several important characteristics of Glauber model from lead isotopes Pb208-under computational analysis. At the start, this paper will provide data under Wood-Saxon distribution in. Then, there are collisions coded from Python, assuming all collisions have reaction cross section of 72 mb, both participant particles and particles under secondary collisions are collected and plot in scatter graphs under impact parameter from 0 fm to 20 fm. Lastly, within the collision area, this paper is going to find the distribution of path length under various parameters.

Investigation on the dynamic behavior of the ring-stiffened double-shell structure due to subsea collisions

The ring-stiffened double-shell structure is currently widely utilized in the equipment for ocean engineering, of which the response analysis under subsea impact is important to accomplish the safety and highly difficult Marine missions. However, due to the complex characteristics of the research object including fluid-solid coupling contact, large deformation, short response time, and multiplet structure, the dynamic behavior of the impacted ring-stiffened double-shell structure is hard to analyze accurately by traditional numerical methods. To overcome challenges, a fresh modeling and solving approach for the impacting mechanism of the structure body is put forward by this paper. The method is based on the Arbitrary Lagrange-Euler and Fluid-Structure-Interaction (ALE-FSI) theory. A stiffness matrix of a penalty function and steady outer pressure setting is presented to build the underwater interaction model. Then, the ALE-based description method is proposed to simulate the collision process. The results indicate that the adopted modeling and solving methods for the subsea structural collision have better revealed the dynamic response process of subsea structure to impact. There isn’t any evident damage spreading to the surrounding region, and the structural damage is primarily contained in the collision area. When an underwater impact is applied to the double shell structure, the non-pressure shell provides better protection. The core academic achievement of this work is providing an effective approach for subsea impacting mechanism and nonlinear dynamic response of ring-stiffened double-shell structure which can be used in different scenarios. It can offer universal references to optimize the construction of underwater equipment and determine the level of impact damage to submarines.

Tectonically Stable Parts in Iraq Are Not Stable

Iraq is located in the extreme northeastern part of the Arabian Plate, which is in collision with the Iranian (Eurasian) Plate. The collision, which is still ongoing has created tens of folds some of which exhibit different types of faults. The exerted compressional forces are believed to be decreasing southwestwards as being far from the collision area (Suture Zone). Accordingly, all the existing tectonic and geological maps compiled by different authors and all the existing published articles, reports and books have considered two main tectonic domains in Iraq. The Stable Shelf and Unstable Shelf or Inner Platform and Outer Platform. The contact between these two main divisions follows almost the Euphrates River; towards the west of the river is the tectonically Stable area and towards the east and north is the tectonically Unstable area, which means the presence of different structural forms. In the current study, we have recognized tens of different Neotectonic evidence in the Stable part indicating that the area is tectonically not stable. Among those indications are abandoned valleys, development of sinkholes along certain lineaments, bending of valleys in right angles, and development of nick-points in valleys along certain lineaments.

Enhancing fog collection by optimizing wettability combination and fork-row collector arrangement: light and heavy fog

Fog collection is essential to alleviate water scarcity in arid areas. However, the vast majority of existing fog collectors only work effectively in heavy fog. To broaden the fog concentration range for efficient work, an optimization strategy based on wettability combination and fork-row arrangement is proposed in this work. Single-layer experiment results show that a hydrophilic (HL) surface with high deposition capacity collects droplets at a faster rate in light fog (25–80 g h−1), while the collection rate of a hydrophobic (HB) surface with high drainage capacity is higher in heavy fog (220–500 g h−1). Double-layer experiment results show that in light fog, the best combination of double-layer collection electrodes is HL–HL, while HB–HL performs best in heavy fog. A 35% improvement in collection rate can be obtained simply by changing the arrangement from smooth-row (S) to fork-row (F), which is attributed to the increased effective collision area of droplets. In our series of experiments, at 50 g h−1, the collection rate of double-layer combination HL–HL(F) is 56.7% higher than that of single-layer HL. In particular, the collection rate of HB–HL(F) reaches 1434.7 mg cm−2 h−1 at 500 g h−1. Such a good performance is attributed to the force imbalance of hanging droplets caused by wettability differences, which tends to transport small droplets on HB towards HL directionally, resulting in a rapid droplet slippage. Therefore, the HB–HL accelerates drainage and refreshes capture points. Furthermore, fog collection performance is also influenced by layer spacing, which has an optimal distance. These findings provide a promising method for practical applications of fog collectors in a wide range of fog flow quantities, enhancing adaptability to variable environments.

The causes of tectonic and seismic activity of the Liskin fault zone (in the southeastern part of the Voronezh uplift of the East European Platform)

The Liskin fault zone located in the southeastern part of The East European Platform on the border of two large neotectonic structures — the Voronezh Uplift and the Oka-Don basin is considered. A concentration of earthquake epicenters is confined to the fault zone and the adjacent territory. The neotectonic structures of the territory, relief, structure of the multi-depth and age horizons of the sedimentary cover, basement, crust, Moho surface are investigated, and the causes of neotectonic and seismic activity of the zone are determined. The Liskin fault at the present time developing as a thrust with right component under the conditions of submeridional compression and the adjacent territory is under the influence of multidirectional tectonic compression stresses: from the north, from the Oka-Don basin and from the south, from the Caucasian segment of the Alpine collision belt. This is reflected in the morphology and structure of the newest structures. The deformation of multi-depth horizons as well as the Earth’s surface and the activating of seismicity are associated with the submeridional compression. The deep material and structural inhomogeneities of the Earth crust are of great importance. For the first time in the newest structure of the south-eastern part of the East European Platform, the collision area of two oncoming submeridional stresses that caused active seismicity has been identified.

On the Grant-Free Random Access in Multicell Massive MIMO Systems: Spatiotemporal Modeling and Backoff Scheme Optimization

Grant-free random access (GFRA) becomes attractive in Internet-of-Things (IoT) due to its low signaling overhead and short access latency. In this paper, we invetigate GFRA in a multicel massive multiple-input-multiple-output (MIMO) system. As the IoT device usually has sporadic traffic, we set a packet buffer for each device to describe its temporal traffic, and also use the stochastic geometry to describe the randomness of devices’ spatial locations. With backoff mechanism, only devices with a non-empty buffer and a successful backoff are activated and allowed to request access. Unlike previous works that regard all devices selecting the same pilot (i.e., the colliding devices) as undetectable, we give a more accurate model that the base station (BS) can detect colliding devices when they locate far away from each other, and we set a unique collision area for each device to quantify the boundary that the collision can be ignored. A tight approximation for the number of packets successfully transmitted at the unit area and time slot, named packet throughput, is derived. Based on it, we obtain the optimal backoff parameter that maximizes the packet throughput under devices’ delay constraints. It is shown that when pilots are insufficient or device packet traffic is heavy, a long backoff time is needed. However, as the pilot grows or the packet traffic turns light, devices should gradually reduce the backoff time. In particular, if pilots are surplus, cheap detectors can be equipped on the BS without an obvious packet throughput reduction.

The collision performance of jack-up marine platforms based on pile-soil coupling technology

The truss jack-up offshore platform has become the main force of offshore oil and gas development with its stable operation ability and environmental adaptability. Meanwhile, along with the development of the offshore shipping industry, collisions between ships and offshore platforms have become more and more frequent. Therefore, it is important to study the collision performance of truss jack-up offshore platforms. Based on the “pile-soil” coupling technology, the non-linear finite element software ABAQUS is used to establish the pile-leg collision calculation model. The key parameters, such as damage deformation, collision force, and energy absorption, are analyzed through the analysis. The collision performance of the trussed offshore platform is analyzed through the calculated damage deformation, collision force, energy absorption, and other key parameters. The research results show that the collision between the ship and the marine platform has obvious local characteristics. In addition, the strength of the spar in the collision area can be increased appropriately to improve the collision performance of the platform effectively.

Evaluation of Automatic Emergency Braking Systems in Two-Wheeler Crash Scenarios

The two-wheeler (TW) is a popular means of transportation in China, but TWs often suffer from serious traffic crashes because of their highly flexible trajectory and low detectability. Therefore, they present a challenge for the sensing and decision-making systems in autonomous vehicles (AVs). Collision avoidance systems, such as automatic emergency braking (AEB), have provided an effective way for AVs to avoid collisions with different objects, including TWs. The effectiveness of the AEB system is highly dependent on its parameter configurations, however, which vary among TW crash scenarios. This study, therefore, evaluates the AEB parameters, including time to collision (TTC), deceleration, and detection area (including detection range, field of vision, and trigger width) in two AEB systems: one-stage AEB and three-stage AEB. A total of 243 crashes extracted from the China In-Depth Accident Study database were simulated in Matlab’s Simulink. Results show: (i) one-stage AEB crash avoidance rates range from 15.2% to 81.5%, while three-stage AEB has crash avoidance rates as high as 87.2%; (ii) deceleration, TTC, and detection area all have significant main effects on crash rate, but detection area has less influence in longitudinal than in crossing scenarios; (iii) higher crash avoidance rates resulted in lower traffic efficiency for both AEB systems, but resulted in greater speed reduction only for one-stage AEB; and (iv) collisions are less likely to be avoided in scenarios with high initial speed of TW and AV. This study demonstrates the performance of AEB algorithms in multiple actual crash scenarios and provides a reliable basis for the development of AEB systems.

МЕТОД ПОСТРОЕНИЯ ОБЛАСТИ ВОЗМОЖНОГО СТОЛКНОВЕНИЯ СУДОВ НА ОСНОВЕ МНОЖЕСТВ ДОСТИЖИМОСТИ

The article has considered the method of vessels possible collision area constructing in problem of guaranteed collision avoidance of controlled vessel with unpredictable target-vessels. Reachable set is expanded with defined safe distance, segments of enlarged set combine and form possible collision area, which is convenient for practical use. Performed researches contribute to the improvement of the ship’s handling methods.

POMDP Motion Planning Algorithm Based on Multi-Modal Driving Intention

On highways, the interaction with surrounding vehicles is very crucial for the decision-making and planning of autonomous vehicles. However, the multi-modal driving intentions of surrounding vehicles have brought great challenges. Aiming at the multi-modal driving intention of surrounding vehicles, a multi-modal driving risk field based on dynamic collision region is proposed, and MDI-POMDP decision framework is established, which integrating behavior decision and motion planning. Firstly, the multi-modal probability distribution of driving intention is fused to establish a driving risk field. Moreover, combined with the longitudinal safety distance model and lateral driving direction, the concept of dynamic collision area is proposed in the driving risk field. Then, MDI-POMDP is formulated to analyze the influence of the uncertainty on planning, which is caused by the multi-modal driving intention of surrounding vehicles. In the following, with the help of the previous state, a time-dependent DRL algorithm RDPG is designed to enhance the current observation, to solve the optimal driving policy under partial observation and generate the optimal trajectory. Furthermore, the simulation results show that the performance of our proposed motion planning algorithm is outstanding, compared with the states-of-the-art methods. And our algorithm has the powerful ability to model the multi-modality of driving intention, to ensure the traffic safety.

An optimization based planner for autonomous navigation in vineyards

Autonomous driving systems found their first applications in the agricultural field, being a way to ease personnel of repetitive jobs and increase precision. Performing operations like harvesting or pruning requires high positioning accuracy, especially in structured environments like vineyards and orchards. In these contexts, the global reference path is dictated by the agricultural procedure to perform. The continuously-changing vegetation and reduced maneuvering space create the need to re-plan the vehicle route with respect to the global reference. Hence, the importance of local planning. This paper proposes a local planning strategy with the objective to follow a park-to-park global path while avoiding obstacles. We formulate the local planning task as a constrained optimization problem. The resulting local plans are not constrained in shape, thus guaranteeing planning freedom, and manage obstacle avoidance in an innovative way. The collision area is precisely determined taking both the vehicle and the obstacles dimension into account, and considering the vehicle approach direction. The proposed system is tested in simulation, where its performance are compared with a benchmark planner. An experimental campaign validates the local planner with satisfactory results.