Collision Mode Research Articles

Dynamic fluid-structure interaction between the projectile and the light-thin ice under the motion state in the polar environment

The interaction between projectiles and ice during water entry is crucial for advancing polar resource exploration and military operations in polar regions. This study introduces a fluid-structure interaction (FSI) model to simulate the dynamics between projectiles and light-thin ice under a motion state, validated through laboratory experiments. It examines the cavity evolution patterns during water entry and analyzes the motion states and dynamic characteristics of both the projectile and the floating ice. The influence of the horizontal-to-vertical velocity ratio (u*) and the initial pitch angle (φ) on the water entry process and collision dynamics has also been considered. The results reveal that as the projectile approaches the floating ice, it generates a wave-making effect, impacting the formation of the water entry splash crown and the deflection motion of the ice. Additionally, the hydrodynamic force acting on the projectile increases by 40 % compared to free water entry conditions. After the collision between the projectile and the light-thin ice, the pinch-off characteristics of the water entry cavity alter. This collision influences the motion state and dynamic characteristics of the projectile, while the ice experiences both collision and hydrodynamic forces, leading to passive motion. With an increasing water entry velocity ratio, the light-thin ice forms an expanding cavity during passive water entry, affecting the cavity pinch-off of the projectile. When u* > 1, the projectile exhibits circuitous motion post-collision with the ice. Variations in water entry angles of the projectile alter the collision mode between the projectile and the ice, resulting in changes to their motion states and dynamic characteristics. A critical pitch angle exists during the cavity pinch-off process.

Experimental investigation on propagation characteristics of rotating detonation wave fueled by diesel

Diesel fuel plays an indispensable role in the energy power sector. Detonation is a self-pressurizing combustion mode that can improve the utilization efficiency of diesel fuel. Through experiments, this paper explored the propagation characteristics of diesel/air RDWs within three different air-inlet slot width structures. A total of 24 high-pressure atomizing nozzles were evenly distributed circumferentially to inject diesel fuel into the combustor. The air, preheated by a heater, was injected into the combustor through the air-inlet slot. The results demonstrate the successful achievement of diesel/air rotating detonation under three different air-inlet slot width structures. As the width increases, the range of operating conditions for achieving detonation becomes more limited. As the air temperature rises, so does the detonation wave's propagation velocity, reaching up to 79 % of the theoretical CJ value. Both single-wave and two-wave collision modes were obtained in the experiments, with a constantly shifting collision point of the two-wave mode, forming the drift phenomenon. The establishment time for the detonation wave is comparatively short, ranging from 2.0 to 5.5 ms, and is minimally affected by the air-inject slot width and the total air temperature. The two-wave collision mode evolved from the single-wave form.

Application of Flores model considering variable recovery coefficient in dynamics analysis of ball bearings

PurposeThis paper aims to select an appropriate contact force model and apply it to the interaction model between the balls and the cage in the rolling bearings to describe the elastic–plastic collision phenomena between the two.Design/methodology/approachTaking the ball–disk collision mode as an example, several main contact force models were compared and analyzed through simulation and experiment. In addition, based on the consideration of yield strength of materials and initial collision velocity, a variable recovery coefficient model was proposed, and its validity and accuracy were verified by the ball–disk collision experiments. Then, respectively, the Flores model and the Hertz model were applied to the interaction between the balls and the cage, and the dynamics simulation results were compared.FindingsThe results indicate that the Flores model has good regression of recovery coefficient, indicating good applicability for both elastic and elastic–plastic contacts and can be applied to the contact collision situations of various materials. Under certain working conditions, there are significant differences in the dynamics results of rolling bearings simulated using the Flores model and Hertz model, respectively.Originality/valueThis paper applies the Flores model with variable recovery coefficients to the dynamics simulation analysis of ball bearings to solve the elastic–plastic collision problem between the rolling elements and the cage that cannot be reasonably handled by the Hertz model.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0138/

FMCW Laser Fuze Structure with Multi-Channel Beam Based on 3D Particle Collision Scattering Model under Smoke Interference.

In the environment of smoke and suspended particles, the accurate detection of targets is one of the difficulties for frequency-modulated continuous-wave (FMCW) laser fuzes to work properly in harsh conditions. To weaken and eliminate the significant influence caused by the interaction of different systems in the photon transmission process and the smoke particle environment, it is necessary to increase the amplitude of the target echo signal to improve the signal-to-noise ratio (SNR), which contributes to enhancing the detection performance of the laser fuze for the ground target in the smoke. Under these conditions, the particle transmission of photons in the smoke environment is studied from the perspective of three-dimentional (3D) collisions between photons and smoke particles, and the modeling and Unity3D simulation of FMCW laser echo signal based on 3D particle collision is conducted. On this basis, a laser fuze structure based on multiple channel beam emission is designed for the combined effect of particle features from different systems and its impact on the target characteristics is researched. Simulation results show that the multiple channel laser emission enhances the laser target echo signal amplitude and also improves the anti-interference ability against the combined effects of multiple particle features compared with the single channel. Through the validation based on the laser prototype with four-channel beam emitting, the above conclusions are supported by the experimental results. Therefore, this study not only reveals the laser target properties under the 3D particle collision perspective, but also reflects the reasonableness and effectiveness of utilizing the target characteristics in the 3D particle collision mode to enhance the detection performance of FMCW laser fuze in the smoke.

Biochemical investigation of association of arsenic exposed polymorphic variants and disease susceptibility

Our study aimed to establish the association of polymorphic variants and disease susceptibility in arsenic-induced metabolic disorders raised due to the variability of arsenic methylation in human population exposed to arsenic in drinking water. Water samples were systematically collected from various regions of Faisalabad, Pakistan, and subjected to arsenic quantification through inductively coupled plasma emission spectrophotometry (ICP-OES). The groundwater exhibited significantly elevated arsenic concentrations (68.18 ± 21.28 μg/L) in comparison to both water and sanitation agency Faisalabad (WASA)-supplied water (9.81 ± 1.2 μg/L) and locally filtered water (8.12 ± 1.42 μg/L), as determined by one-way ANOVA followed by Bonferroni's post-test at P < 0.05. An association was established between arsenic concentration and the incidence of disease, such as diabetes mellitus. A cohort of 120 participants residing in six areas of District Faisalabad was recruited. Urine and blood specimens were collected for analysis. Urine samples underwent ICP-MS analysis in helium collision mode, utilizing germanium as an internal standard. Blood samples were collected for biomarker assessments, including HbA1c, BUN, creatinine, CRP, ALT, AST, GSH, SOD, and MDA, to investigate the evidence of diabetes mellitus. Urinary arsenic concentrations were found to be considerably higher (P < 0.05) in about 22.50 % of the participants, with a mean value of 68.43 ± 16.73 ppb. Biomarker analysis in these participants revealed mean values for BUN (37.19 ± 2.87 mg/dL), creatinine (2.58 ± 0.18 mg/dL), IL-6 (11.35 ± 6.98 pg/mL), CRP (1.90 ± 0.26 mg/dL), MDA (3.70 ± 0.18 nmol/mL), ALT (40.27 ± 5.41 U/L), and AST (38.92 ± 4.72 U/L). Furthermore, the gender-based analysis indicated the higher levels of DMA, MMA, TAs, and TiAs in males compared to females when urine samples were analyzed with HPLC-ICP-MS. Participants with the positive genotype of GSTM exhibited significantly higher levels of TAs, and TiAs concentration in their urine than those with the null genotype of GSTM. Moreover, participants with positive genotypes for GSTT1 and GSTM1 demonstrated elevated levels of DMA in their urine compared to those with genotypes of GSTT1 (−) and GSTM1 (−), although this difference did not attain statistical significance. Participants with the genotype of GSTT1 (+) displayed a considerably higher secondary methylation index than those with genotype of GSTT1 (−). MMA and DMA levels were found to be correlated with the genotypes of GSTT1 and GSTM1 and the amounts of TAs in urine. In conclusion, our findings suggest a linkage between arsenic methylation, particularly levels of DMA and SMI, and GSTT1 and GSTM1 polymorphisms.

Numerical Investigation on the Influence of Continuous Rotating Backpropagation Pressure Wave on Turbine Performance

Abstract Researches have shown that the use of a continuous detonation afterburner can improve the propulsion performance of aero engine. However, backpropagation pressure waves (BPW) generated by the pressure gain of detonation will affect the internal flow and performance of turbine. This article simulates BPW through a custom function, and investigates the effects of BPW amplitude, rotation frequency, and propagation mode on turbine performance through three-dimensional simulation. The results show that as the pressure amplitude of the BPW increases, the pressure oscillation at each section of the turbine increases and a local subcritical flow state will appear, leading to the decrease of turbine flowrate and turbine power, as well as an intensification of instantaneous turbine power fluctuations. As the rotation frequency of the BPW increases, the pressure oscillation at each section of the turbine gradually decreases. The flowrate and power of the turbine do not change much, but turbine efficiency gradually decreases. Compared to the aligned mode, the turbine performs better under the influence of BPW in misaligned mode. Compared to the single-wave mode, the fluctuation of transient turbine power is lower under the influence of BPW in the multiwave mode excluding collision mode. Finally, the constraints of equal flowrate region and equal turbine power line on the peak-to-peak value of the BPW were analyzed when the joint operation of the turbine and compressor was not affected. The rotation frequency and mode of BPW will affect the flowrate region and power line.

Playing lato–lato is difficult and this is why

Lato–lato, a pendulum-based toy gaining popularity in Indonesian playgrounds, has sparked interest with competitions centered around maintaining its oscillatory motion. While some find it easy to play, the challenge lies in sustaining the oscillation, particularly in maintaining both ‘up and down collisions.’ Through a Newtonian dynamics numerical analysis using Python (code by ChatGPT), this study identifies two equilibrium phases—phase 1, characterized by normal pendulum motion, and phase 2, the double collision mode—using the driven oscillation model. In addition, further analysis and discussion are done using the obtained numeric data. The difficulty in remaining in phase 2 highlights the intricate hand-eye coordination required, shedding light on the toy’s appeal and the skill it demands.

Research on the performance of GMCBO methodology based on model updating of a pedestrian bridge

Consider the loss of diversity of the bodies at the later optimization stage and the low efficiency of the global searching ability of the traditional colliding bodies optimization algorithm in dealing with complex optimization issues of practical structures. Herein, an improved colliding bodies optimization method combing Gaussian-white-noise mutation and innovative collision mode is proposed. The introduction of Gaussian-white-noise is mutating the positions of the selected bodies and enriching the diversity during the whole optimization process. The changed collision mode from ‘one to one’ to ‘one to best’ is accelerating the process to global extremum. During searching the global extremums of the 12 test functions which are unimodal, multimodal and multimodal with fix dimension, the proposed shows relatively better accuracy and efficiency. The comparison based on the maximum, minimum, average, standard deviation and non-parametric Wilcoxon test of the optimization results by the above algorithms confirmed the outstanding performance of the proposed method. Through the application of the proposed method to the model updating of a pedestrian bridge, all the differences of the first five frequencies between the measured vibration data and finite element model are reduced from approximate 25% to nearly 5%, and the updated dynamic characteristics show great agreement with the practical structure. From the comparison of the responses between updated model and human-induced vibration experiment, most of the response differences are around 10%. The application of the above real structure further verifies that the proposed method is feasible and strongly recommended in optimization issues of practical structures.

Effect of ethylene-rich gas temperature on rotating detonation auto-initiation process

In this study, the propagation characteristics of a rotating detonation wave (RDW) between ethylene-rich gas and ambient air were investigated experimentally. The traditional pre-detonator initiation method was abandoned in the experiment, but the spontaneous combustion of high-temperature ethylene-rich gas and air was adopted. The RDW auto-initiated through the deflagration-to-detonation transformation (DDT) process. With an increase in the ethylene-rich gas temperature, the modes of RDW propagation appeared as delayed initiation, dual-wave collision, and fluctuating dual-wave collision modes. When the gas temperature was too high, a secondary detonation wave was produced near the head of the rotating detonation chamber (RDC), which affected the propagation efficiency and stability of the RDW. The increase in gas temperature expanded the equivalence ratio range of auto-initiation, which was due to the higher gas temperature, and more highly active components were precipitated.

Determination of trace elements in superalloys by inductively coupled plasma mass spectrometry with micro-reaction pretreatment

Due to complex pretreatment processes and the consumption of large amounts of high-purity chemical reagents, traditional analytical methods for determining trace element concentrations in superalloys face severe challenges. In this paper, a micro-reaction pretreatment method was developed by using a micro-reaction sealed digestion vessel under micro-pressure. The mass of the samples and the volume of acid used to dissolve the superalloys were significantly reduced. The appropriate amount of digestive acid for micro-reaction and three generalized pretreatment methods were studied. The quantitative dilution process was optimized to minimize errors through meticulous weighing procedures using a high-precision balance, and the homogeneity of the samples was verified by using Ni-based superalloy standards and general samples. Sc, Rh, and Re were selected for internal standard correction, and the matrix effect was corrected by the matrix matching method. Moreover, the mass spectral interference caused by polyatomic ions was eliminated by He collision mode. The linear correlation coefficients of the calibration curves were above 0.9995, with linear coefficients ranging from 0.2 to 100 ng/g. The detection limits for the method ranged from 0.0042 to 0.13 μg/g, and the quantification limits ranged from 0.014 to 0.41 μg/g. The results showed the precision and reliability of the newly established green micro-reaction pretreatment scheme for the determination of Ga, As, In, Sn, Sb, Tl, Pb, and Bi in nickel-based superalloys together with inductively coupled plasma mass spectrometry. The micro-reaction test results of the various groups were consistent with those of the traditional methods, and the relative standard deviation (RSD, n = 11) was less than 10 %. In addition to reducing acid consumption and increasing the test solution utilization rate by ten times, the micro-reaction method was much more accessible from cross-contamination and intensive manual work, so it has shown great potential for application in intelligent and automatic batch testing of trace elements in superalloys.

Research on Optimization Design of Front and Side Structures under the 24th Edition of C-NACP Automotive Collision Standard

Structural crashworthiness plays a core role in vehicle safety design, mainly focusing on the maximum impact force that the body structure can withstand in collision accidents, and striving to maximize collision energy absorption to ensure that passengers have sufficient living space. The design of structural crashworthiness needs to consider the deformation mechanism and energy absorption characteristics of vehicles under different collision modes, and improve crashworthiness through material selection, structural optimization, and other means. In addition, the structural crashworthiness is closely connected to the passenger restraint system, which together constitute the key to the passive safety performance of the vehicle. In vehicle safety design, the improvement of structural crashworthiness can significantly enhance the vehicle's ability to protect passengers in collision accidents and reduce the risk of injury. Therefore, in-depth research on structural crashworthiness and the development of efficient crashworthiness structures are important directions for improving vehicle safety performance.

The Fast Quantification of Vitamin B12 in Milk Powder by High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry.

This study presents a new technique for determining vitamin B12 in milk powder using high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). We used ultrasonics with potassium ferrocyanide and zinc acetate solutions to extract the samples. 59Co was employed as the analytical target for cyanocobalamin. It was separated using a Phenomenex Luna 5 μm C18 (250 × 4.6 mm) chromatographic column with a mobile phase consisting of 1.6 mmol/L EDTA and 0.4 mmol/L KH2PO4 in a 60% v/v methanol solution (pH = 4.0). The sample has an excellent separating degree for free cobalt and cyanocobalamin, and isocratic elution can be finished within 4.0 min. To eliminate the matrix interference due to the presence of milk powder, we applied collision mode (KED). The linear range of cyanocobalamine ranged from 1.0 μg/L to 20 μg/L, with correlation coefficients (r2) of 0.9994. The limit of detection (LOD) was 0.63 μg/kg, and the limit of quantitation (LOQ) was 2.11 μg/kg. The mean recoveries were in the range of 87.4-103.6%. The accuracy and precision of the developed method are well suited for the fast quantification of the trace vitamin B12 in milk powder.

Numerical Investigations of Collision Modes of Double Droplets on a Spherical Surface Based on the Phase Field Method

Numerical Investigations of Collision Modes of Double Droplets on a Spherical Surface Based on the Phase Field Method

Effect of fluid–structure interaction on the oblique water entry of the projectile under the influence of floating ice structure

The water entry of a projectile constrained by polar floating ice presents a unique cross-media challenge. This paper investigates the dynamics of oblique water entry for a projectile influenced by floating ice using the fluid–structure interaction (FSI) method. The validity of the numerical method has been confirmed through experimental validation. The water entry process of a projectile from the side of the floating ice is examined. The evolution of the cavity and the movement patterns of objects as the distance between the projectile and the floating ice decreases toward collision are investigated. The influence of water on the critical collision distance between the projectile and the floating ice during oblique water entry is analyzed. Additionally, the physical mechanism of floating ice deflection through collision is investigated based on the theory of cavity dynamics. Subsequently, the study focuses on the oblique water entry process of a projectile colliding with the upper surface of the floating ice. Different entry angles determine the collision mode between the projectile and the floating ice surface. This study also examines how varying entry angles influence cavity evolution and object movement patterns during oblique collisions. Different collision modes between the projectile and the floating ice lead to asymmetric cavity evolution and various modes of object deflection motion. Finally, changes in the flow field and vortex structure during oblique collisions are studied to examine the influence of the FSI process between the projectile and the floating ice on the flow field.

Variation in traffic injury settings—same implication of hospital and police-based traffic injury data?

IntroductionInjury and death from traffic incidents are still a major global concern and are associated with significant costs. Traffic incidents are preventable, but this requires planning based on accurate and complete injury data, otherwise efforts bypass targets. ObjectivesThe objective was to compare the agreement between hospital and police records for parameters independently recorded by both datasets and to report the most frequent traffic incident setting reported by either dataset. MethodsWe analyzed routinely collected hospital records from Odense University Hospital, Denmark, for traffic injuries from 2015 to 2021. These include patient demographics and incident-related data (time and place of incident, road users involved, and collision mode) for all patients involved in traffic incidents. These injuries were then linked with police records from Funen Police District, which covers the same geographical area of the island Funen, Denmark. ResultsIn total, 21,562 road users were injured and subsequently treated at the hospital, and 5176 (24.0%) of these suffered from severe injury.The agreement between hospital and police records was for means of transport (passenger car/bicycle/moped/pedestrian/motorcycle) 93.9% [95% confidence interval: 93.0%, 94.9%], role (driver/passenger/pedestrian) 97.7% [97.1%, 98.3%], and use of seat belt/helmet 76.9% [75.2%, 78.6%]. The accuracy of police severity classification was 50.5% [47.0%, 54.0%], and the completeness of police-reported severe incidents was just 15.1% [14.1%, 16.0%] compared with hospital records.The top-5 hospital-reported severe traffic incident setting was an injured cyclist with no counterpart on a city road (n = 1130), and 4 of 5 in this top-5 involved an injured cyclist.The top-5 police-reported severe traffic incident setting was an injured cyclist with a passenger car counterpart on a city road (n = 116), and the remaining 4 in this top-5 involved an injured passenger car driver. Only one setting overlapped between hospital- and police-reported top-5 severe injury scenarios. ConclusionThis study showed an extraordinarily high agreement between parameters independently recorded by hospital and police records, but police records misclassify severity and is not a reliable source for severe injuries.Thus, road safety policies may not have the intended effect if preventive efforts are based solely on police-reported severe injuries. With the documented agreement on means of transport, role, and use of safety equipment we suggest that planning of preventive efforts is based on hospital records in areas where registration practices are sufficiently thorough supplemented by police data.

Rapid determination of chromium species in environmental waters using a diol-bonded polymer-stationary column under water-rich conditions coupled with ICPMS.

Chromium speciation analysis in environmental water is of great significance for the monitoring of water pollution and assessing its influences on human health. This study proposes a rapid analytical approach for the simultaneous determination of Cr(VI) and Cr(III) in environmental waters by hydrophilic interaction chromatography (HILIC) coupled with ICPMS under a water-rich condition. 2,6-Pyridinedicarboxylic acid (PDCA) was used to unify Cr(III) species in various chemical forms into a stable Cr(III)-PDCA anion complex and then separated from Cr(VI) oxyanion on a diol-bonded polymer-based HILIC column. An aqueous mobile phase containing 50mmol L-1 ammonium acetate (pH 7.0), 2mmol L-1 PDCA, and 4% acetonitrile successfully separates chromium species as well as chloride ions. In addition, our method elutes Cr(VI) preferentially over Cr(III)-PDCA, enabling rapid determination of Cr(VI), and both chromium species were analyzed within 6.2min. The detection limits of 0.19μg L-1 for Cr(VI) and 0.35μg L-1 for Cr(III) at m/z 52 under He collision mode are comparable to or better than the conventional ion exchange chromatography-ICPMS methods, and quantitative recovery was obtained from spike-recovery tests on river water samples containing various levels of matrix. Optimization experiments of the HPLC conditions indicate that the retentions of Cr(VI) and Cr(III)-PDCA are characterized by electrostatic and nonpolar interactions, respectively. The retention behavior of inorganic anions and cations in water-rich conditions observed in this study will provide new insights into the separation mechanism in polymer-based HILIC columns, which has been poorly understood.

Study on the mechanism of water entry under the effect of floating ice based on a penalty function-based fluid–structure interaction method

Water entry in polar regions is a hot topic of mechanical dynamics. Nonetheless, the presence of floating ice can significantly influence the water entry process. In this paper, a novel two-way fluid–structure interaction (FSI) scheme based on the penalty function is proposed that is suitable for collision between objects into the water. In this scheme, the collision between the projectile and the floating ice is solved by the penalty function, and then, the collision information is transmitted to the fluid solver to solve the passive water entry process. Using dynamic models and experimental data, the accuracy of the new FSI scheme is validated. The cavity evolution and dynamic response of the floating ice colliding with the projectile are studied. During passive water entry, the development of the splash crown is inhibited. The contact line at the floating ice exhibits different movement states under different mass ratios (M). Subsequently, the passive water entry of eccentric collisions is studied, and the influence of eccentricity (Liz*) is considered. Different collision modes and contact-sliding modes occur between the floating ice and the projectile during the eccentric collision. The evolution of the cavity also appears to have asymmetric characteristics. The horizontal displacement of the floating ice influences the transition of the collision mode under the same wetted area.

The role of continental lithospheric thermal structure in the evolution of orogenic systems: application to the Himalayan–Tibetan collision zone

Abstract. Continental collision is a crucial process in plate tectonics. However, in terms of the evolution and the controlling parameters of its lateral heterogeneity, our understanding of the tectonic complexities at such a convergent plate boundary remains largely unclear. In this study, we conducted a series of two-dimensional numerical experiments to investigate how continental lithospheric thermal structure influences the development of lateral heterogeneity along the continental collision zone. The following two end-members were achieved. First, continuous subduction mode, which prevails when the model has a cold procontinental Moho temperature (≤450 ∘C). In this case, a narrow collision orogen develops, and the subducting angle steepens with the increasing retrocontinental Moho temperature. Second, continental subduction with a slab break-off, which generates a relative wide collision orogen and dominates when the model has a relatively hot procontinental Moho temperature (≥500 ∘C), especially when the Moho temperature ≥ 550 ∘C. Radioactive heat production is the second-order controlling parameter in varying the continental collision mode, while it prefers to enhance strain localization in the upper part of the continental lithosphere and promote the growth of shear zones there. By comparing the model results with geological observations, we suggest that the discrepant evolutionary paths from the continuous subduction underlying the Hindu Kush to the continental subduction after slab break-off beneath eastern Tibet may originate from the inherited lateral inhomogeneity of the Indian lithospheric thermal structure. Besides, the high content of crustal radioactive elements may be one of the most important factors that controls the formation of large thrust fault zones in the Himalayas.

Temporal Instability Analysis of Injury Severities for Angle and Non-Angle Crashes at Roundabouts

Roundabout crashes are common worldwide but have received little attention. In particular, the investigation remains relatively understudied in distinct collision modes of roundabout crashes, including angle and non-angle crashes. This study investigates differences in factors affecting injury severity between angle and non-angle crashes and how these differences change over time. Random parameter logit models with heterogeneity in mean and variance were estimated using 2012–2019 Florida crash data. Variables considered for the modeling include temporal characteristics, environmental characteristics, road characteristics, spatial characteristics, vehicle characteristics, crash characteristics, and human characteristics. In addition, likelihood ratio tests were used to investigate the temporal instabilities of the models and differences in collision modes. The results showed that only a few variables demonstrated temporally stable effects for angle collisions (weekend and dark-lighted) and non-angle collisions (paved shoulders and cyclists), respectively. Unique influencing factors of injury severity were identified for different collision modes, such as dark-lighted, straight alignment, merge, lane departure, the disabled driver for angle collisions, and clear, fog, commercial vehicles, and aggressive driving for non-angle collisions. The results of the out-of-sample prediction simulations further demonstrate the difference in injury severity over time for angle and non-angle collisions. Overall results suggest that countermeasures can be implemented to reduce the injury severity of angle crashes/non-angle crashes based on the significant variables identified. This study may be used to improve roundabout safety by considering different collision modes.

Study on water entry characteristics of the projectile colliding with the floating ice based on fluid-structure interaction method: Dynamic response and energy conversion

This study investigates the water entry process of the collision between the ocean detector and the floating ice in polar environments, which is crucial for detecting polar ocean energy. The study utilizes the fluid-structure interaction (FSI) method to analyze the dynamic characteristics of the projectile colliding with the floating ice and the energy change between objects. The effect of the size, structure, and distribution of the floating ice on the water entry process is also taken into account. Experiments have verified the accuracy of the FSI method. The presence of floating ice alters the cavity evolution and subsequently affects the water entry state of the projectile. The width of the floating ice also has a noticeable effect on the cavity evolution during collision water entry. Smaller floating ice sizes result in lower kinetic energy loss after the projectile collides with the floating ice. As the mass of the floating ice increases, the elastic strain energy generated by the projectile when it first collides with the floating ice increases. After the collision separation, the elastic strain energy generated by the second collision is also greater. Additionally, stress concentration occurs during the collision, and the hydrodynamic force on the object is influenced by the evolution of the cavity. When the projectile collides with the edges of the floating ice on both sides, a unique spherical splash crown is formed. This collision mode results in a lower loss of kinetic energy and elastic strain energy compared to colliding with single floating ice.