Impact Location Research Articles

Droplet impact on sparse hydrophobic pillar surface: Impact phenomena, spreading mode, and droplet breakup

Functional surfaces with controllable droplet spreading and breakup dynamics have received widespread attention in self-cleaning, spraying cooling, 3D printing, etc. The arrangement of a microstructure is of great value for the design of functional surfaces. Here, we numerically investigated the droplet impact dynamics on the sparse hydrophobic pillar surface with OpenFOAM. We investigated the effect of Weber number, impact locations, and pillar spacing. Outcomes are most strongly influenced by impact locations, pillar pitch, Weber number, and eight spreading patterns were registered, including circle, square, cross-shaped, Chinese knot, octopus, ellipse, dumbbell, and hexagram. Furthermore, a set of theoretical models were developed for the spreading pattern transition to predict the critical Weber number for different droplet spreading patterns. The breakup dynamics of droplets strongly depend on the spreading patterns and the impact location, which can emit secondary droplets in specific directions. The cross pattern significantly reduces the threshold for secondary droplet generation. The results obtained some essential characteristics for droplet impinging sparse hydrophobic pillar surface, which could provide valuable insights into functional surface design, fluidic-based systems and applications.

Research on impact localization method based on passive tomography of piezoelectric sensors

Impact monitoring of plate structures has always been a hot spot in structural health monitoring research. In order to improve the accuracy of impact monitoring, this paper proposes a beam-focusing impact localization algorithm based on passive tomography using a sensor arrangement method in a ring array. The impact damage monitoring of large-sized structures in different directions is performed by each linear array of the ring array and the impact damage localization distribution maps of the corresponding linear arrays are generated. The localization accuracy of the linear arrays in different directions is obtained experimentally to assign the weights of each linear array to achieve image reconstruction of the impact damage. The experimental results show that the method can achieve a more accurate visualization of the impact location, and the reconstructed impact laminar image can well reflect the impact location distribution information. It can be used for the localization of impact damage and extended monitoring.

3D Radiative-transfer Simulations of the Ejecta Plume Anticipated from DART Impact

We present a modeling approach that allows the reconstruction of detailed images of the ejecta plume produced by the DART impact on asteroid Dimorphos. The approach is based on the 3D radiative-transfer technique and uses the publicly available HYPERION software package. The modeling automatically includes all interactions of light with the asteroid and ejecta plume, including transmission of the light through a hollow cone, reflection from the asteroid, and second transmission through the ejecta for each point within the ejecta plume and asteroid surface. The results of the modeling are the FITS images of the asteroid and ejecta as they will be seen by the LEIA camera on board LICIACube for any specific moments after impact. The parameters of the modeling are preimpact assumptions regarding Dimorphos’ shape and composition, the presumed impact location, and the planned flyby trajectory of LICIACube. The results of the modeling show the readiness of our modeling tools to simulate the realistic ejecta plume after impact with the purpose to model the LICIACube images at different moments after impact and estimate the properties of the dust ejecta particles and the ejecta mass.

Computational modeling and dynamic response of reinforced concrete shear wall under out-of-plane impact loading

The purpose of the present work is to study the impact performance of the reinforced concrete shear wall. Considering the bond-slip and strain rate enhancement effects of steel and concrete, a numerical model for the study of the impact resistance of reinforced concrete shear walls was established. The numerical model was validated by comparing the simulation results with those observed during the drop hammer impact test. Based on the simulation results, the failure mechanism of reinforced concrete shear walls under impact loading was analyzed. The influence of impact velocity and edge members on the impact resistance of reinforced concrete shear walls was revealed. The results show that the dynamic response of the wall changes most obviously from the instant of peak impact force to the peak reaction force. The damage on the rear surface of the wall is more serious than the impact surface. The local damage of reinforced concrete shear walls is more serious for higher impact velocity. The maximum and residual displacement in the middle of the wall shows a quadratic growth relationship with the impact velocity and a linear growth relationship with the impact energy. With the increase in impact velocity, the peak and platform value of impact force first increase linearly, and then does not change remarkably while the duration increases linearly. The peak reverse reaction force varies irregularly with the increase in impact velocity due to the inertia of the wall. The influences of impact velocity and edge members on the value and duration of reaction force are similar to those on the impact force. Under impact loading, both the maximum positive and negative bending moment appear in the area near the impact location. The increase in impact velocity can elevate the internal force while edge members affect the shear force more than the bending moment. The change in impact velocity affects the energy distribution in steel and concrete during impact. Configuration of edge members can effectively enhance the impact resistance of the wall due to the improvement in global stiffness. The mid-span displacement of the wall and the duration of impact force are reduced and the energy dissipation capacity of concrete is improved.

Head impacts in non-helmeted sports: Measuring and locating the impact force

Mild traumatic brain injury within contact sports is a growing concern due to the serious risk of injury and concussion. Extensive research is being conducted looking into head kinematics during impacts in non-helmeted contact sports utilizing instrumented mouthguards, allowing researchers to record accelerations and velocities of the head during and after an impact. This does not, however, allow the location of the impact on the head, and its magnitude and orientation, to be determined. This research proposes and validates an algorithm using rigid body dynamics that approximates the impact force and determines its location and orientation from instrumented mouthguard kinematic data. Impact data captured from an experimental laboratory test using an instrumented mouthguard and five finite element simulations are used to validate the algorithm. The obtained results from both validation methods highlight the effectiveness of the proposed impact magnitude and location algorithm as impact locations were calculated within 12 mm of the impact center for all conducted tests. Additionally, components of force unit vectors (direction cosines) obtained from the algorithm were within ±0.03, which equates to less than 11% of the components of applied force unit vectors, highlighting the accuracy of impact direction vector established from the algorithm. This algorithm has the potential to significantly aid researchers conducting field tests within non-helmeted sports by reducing the time required to analyze and determine head impact locations.

Post‐flood infectious disease prevention and control: Current scenario in Pakistan

Post‐flood infectious disease prevention and control: Current scenario in Pakistan

Bird impact response and damage mechanism of 3D orthogonal woven composite aeroengine blades

Various gelatin simulated bird projectiles were used to impact two key positions of three-dimensional (3D) orthogonal woven composite stator blades used in aeroengines: the center and leading edge at the blade back. The effects of impact velocity, projectile weight, and impact position on the macro damage mode were determined. Numerical simulations were conducted using the constitutive model developed in our previous work (Liu et al. 2023). The numerical simulation results were in good agreement with the experimental results. Combined test results, micro-CT and SEM observation and the numerical simulation results, the internal damage mechanism of the blade was explored. Four types of damage modes were seen under bird strike: edge damage on the narrow blade root, cracks on both sides of the narrow blade root, damage in the impact area, and complete fracture. Furthermore, the impact energy thresholds for visible damage and fracture were obtained for different bird weights and impact locations, which is of great significance to the anti-bird-strike design of composite blades.

Plausible Differences between the Laboratory and Prototype Behaviors of Spillway Aerator Flows

An aerator, installed to prevent cavitation damages in spillways and outlet works, generates a typical two-phase flow affected by its configuration and flow conditions. The major parameters of concern include air demand, jet trajectory and streamwise changes of air concentration near chute bottom. This study reviews the theoretical basis and deals with several aspects of physical scale modeling, supported exclusively by field measurements. Analyses reveal that the sub-atmospheric pressure generated in the air cavity should also be scaled in physical modeling, which is seldom the case in the laboratory environment. Thus, the conventional approach to upscale the air demand is controversial. With the data from both fields and laboratories, it is demonstrated that a direct conversion of air flow from model to prototype is justified only if the approach flow velocity in the model exceeds 7.0–7.5 m/s or the Reynolds number exceeds 1.58 × 106. Failing to meet this premise would bring about errors for prototype predictions; the error extent depends on both model scale and flow magnitude. In terms of cavity pressure drop, the prototype differs by a factor of less than 10 from its scale model with sufficient air supply. In a model, the air concentration along the chute bottom drops considerably within one to two trajectory lengths. The prototype differs from its model in such a way that the air concentration decay is much slower, with a higher level that is maintained over a longer distance downstream of the impact location. This study is intended to provide insight for laboratory studies and engineering design.

Whitewater Helmet STAR: Evaluation of the Biomechanical Performance and Risk of Head Injury for Whitewater Helmets.

More than six million people participate in whitewater kayaking and rafting in the United States each year. Unfortunately, with these six million whitewater participants come 50 deaths annually, making it one of the highest fatality rates of all sports. As the popularity in whitewater activities grows, the number of injuries, including concussions, also increases. The objective of this study was to create a new rating system for whitewater helmets by evaluating the biomechanical performance and risk of head injury of whitewater helmets using the Summation of Tests for the Analysis of Risk (STAR) system. All watersport helmets that passed the EN: 1385: 2012 standard and that were clearly marketed for whitewater use were selected for this study. Two samples of each helmet model were tested on a custom pendulum impactor under conditions known to be associated with the highest risk of head injury and death. A 50th percentile male NOCSAE headform instrumented with three linear accelerometers and a triaxial angular rate sensor coupled with a Hybrid III 50th percentile neck were used for data collection. A total of 126 tests were performed using six different configurations. These included impacts to the front, side, and rear using two speeds of 3.1 and 4.9m/s that modeled whitewater river flow rates. Each helmet's STAR score was calculated using the combination of exposure and injury risk that was determined from the linear and rotational head accelerations. The resulting head impact accelerations predicted a very high risk of concussion for all impact locations at the 4.9m/s speed. The STAR score varied between helmets indicating that some helmets provide better protection than others. Overall, these results show a clear need for improvement in whitewater helmets, and the methodologies developed in this research project should provide manufacturers a design tool for improving these products.

Impact Mitigation Properties and Material Characterization of Women's Lacrosse Headgear.

The purpose of this study was to examine the impact attenuation properties of women's lacrosse headgear and to characterize mechanical properties of the materials of which they are composed. Impacts using a linear impactor (2.2, 2.9, and 5.0m/s) and a projectile shooter (13.4 and 27.0m/s) were applied to a Hybrid III 50th male head-neck assembly at six impact locations to replicate realistic women's lacrosse head impacts. Individual materials that make up the headgear were tested in compression at two quasi-static strain rates, 0.01/s and1/s, and 100/s using uniaxial test machines. For the linear impactor tests, results showed a significant decrease in peak linear and rotational acceleration (PLA and PRA), peak rotational velocity (PRV), head injury criteria and brain injury criteria in the helmeted impacts (p < 0.022). During the ball impacts PRV and PRA were significantly lower for both helmeted conditions compared with no helmet (p < 0.01). Material characterization tests indicated a range of rate effects in these materials ranging from weak to pronounced, and these effects correspondingly influenced the strain energy density graphs. The connection of the materials' rate effects to the performance of the headgear is described in general and in relation to the impact tests.

Management of oesophageal foreign bodies in children: a 10-year retrospective analysis from a tertiary care center

ObjectiveOesophageal foreign bodies (EFBs) are a common emergency issue in paediatrics, and few studies have revealed its clinical features and treatment methods. We conducted this retrospective study to provide our 10-year clinical evidence for the diagnosis and treatment of EFB and reduce the incidence of complications.MethodsWe retrospectively reviewed all paediatric cases diagnosed with EFB from January 2012 to December 2021 at Shenzhen Children’s Hospital. The age and sex of the patients, types of foreign bodies (FBs), preoperative examination, location and duration of FB impaction, clinical symptoms, surgical methods, therapeutic effects and complications were analysed.ResultsAmong the 1355 cases, 759 were boys and 596 were girls, with a median age of 2.9 years (4 months to 16 years). The shortest FB lodged time was 1 hour, while the longest time was 3 months. The types of foreign bodies included coins and blunt objects (812,59.9%), bones and sharp objects (278,20.5%), button batteries (86,6.3%), food impactions (84,6.2%), toys (51,3.8%) and plastic objects (44,3.2%). A total of 720 of 812 cases impacted by coins and blunt subjects were successfully treated with a Foley catheter without any complications. A total of 558 patients underwent rigid oesophageal endoscopy under general anaesthesia, and foreign bodies were successfully removed in 525 cases. No FB was found in 33 cases, and FBs pushed into the lower digestive tract during operation in 5 cases. Oesophageal injury was found in 130 cases (23.3%). Our study showed that the age of the patient, time of foreign body incarceration, type of foreign body, location of the lodged foreign body, and fever or cough were risk factors leading to oesophageal foreign body complications, and the differences were statistically significant (P < 0.05).ConclusionChildren with EFB have a risk of complications, especially if the FB is a button battery. The appropriate surgical method should be selected through the analysis of the clinical characteristics of the foreign body in the oesophagus and the risk factors for complications to reduce the incidence of complications. Health education and effective care are the keys to the prevention of EFB.

Factors That Guide the Diagnosis and Treatment Planning for Impacted Canines Using Three-Dimensional Cone-Beam Computed Tomography: A Cross-Sectional Study.

Objective Impacted canines are one of the significant challenges in orthodontics that should be appropriately assessed to provide the best treatment to the patients. Materials and Methods In the present study, 57800 patients were examined over six years to investigate the prevalence, diagnostic procedures, and treatment methodologies for impacted canine cases. Prevalence and diagnosis were tested using history taking, clinical examination, and three-dimensional cone-beam radiographs. The cases were tested for impaction site, gender, age, signs, and symptoms. The groups were classified for impaction location according to Mupparapu's classification. Result The causative factors and the treatment methodology selected were plotted according to age and gender distribution. The total prevalence was 3.9% of canine impaction cases in relation to the total sample cases. The results showed a strong correlation between the site of impaction toward the upper arch and with distribution following Mupparapu's classification. The pain was the most detectable complication in all age groups, while root resorption was the least. Conclusion Most of the younger age groups were sent for exposure and orthodontic traction, while the mid-aged groups elected for observation, and follow-up as their primary concern was esthetics. However, the adult patients were into exposure and traction to improve their function.

Influence of the frame of reference on head acceleration events recorded by instrumented mouthguards in community rugby players

ObjectivesTo highlight the need for standardisation in the communication of head impact telemetry from instrumented mouthguards (iMG). The purpose of this study is to examine how the frame of reference...

Bulge formation inside quiescent lopsided stellar disks: Connecting accretion, star formation, and morphological transformation in a z ∼ 3 galaxy group

We present well-resolved near-IR and submillimeter analysis of the three highly star-forming massive (&gt; 1011 M⊙) galaxies within the core of the RO-1001 galaxy group at z = 2.91. Each of them displays kpc scale compact starbursting cores with properties consistent with forming galaxy bulges, embedded at the center of extended, massive stellar disks. Surprisingly, the stellar disks are unambiguously both quiescent and severely lopsided. Therefore, “outside-in” quenching is ongoing in the three group galaxies. We propose an overall scenario in which the strong mass lopsidedness in the disks (ranging from factors of 1.6 to &gt; 3) likely generated under the effects of accreted gas and clumps, is responsible for their star-formation suppression, while funnelling gas into the nuclei and thus creating the central starbursts. The lopsided side of the disks marks the location of impact of accretion streams, with additional matter components (dust and stars) detected in their close proximity directly tracing the inflow direction. The interaction with the accreted clumps, which can be regarded as minor mergers, leads the major axes of the three galaxies to be closely aligned with the outer Lyman-α-emitting feeding filaments. These results provide the first piece of observational evidence of the impact of cold accretion streams on the formation and evolution of the galaxies they feed. In the current phase, this is taking the form of the rapid buildup of bulges under the effects of accretion, while still preserving massive quiescent and lopsided stellar disks at least until encountering a violent major merger.

Impact sensing and localization in composites structures with embedded mechanoluminescence-perovskite sensors

Mechanoluminescence (ML)-perovskite sensors have shown potential for real-time impact sensing in composites structure. The sensors can be embedded in the structure for in-situ and real-time structural health monitoring (SHM) applications. Our previous work demonstrated the potential of a flexible ML-perovskite sensor for SHM systems and the possibility of sensor embedment in a fiber-reinforced composite structure. However, the viability of the sensor to predict impact localization remains unexplored. This paper investigates the potential of the sensors for impact localization in composite laminates. Herein, embedded ML-perovskite sensors are placed throughout a composite plate to monitor the host structure. By monitoring and correlating the changes in the electrical current of the sensors, it is possible to predict the impact location in the structure. The experimental results show that the ML-perovskite sensor can accurately detect and locate impact events when embedded in a composite structure. This work reveals the potential of ML-perovskite sensors for damage detection and localization prediction in composite materials. • A Mechanoluminescence-based sensor was integrated with a perovskite photodiode for in-situ impact sensing. • The sensor was able to detect low-energy impacts when embedded in a composite panel. • A network of sensors was embedded in a composite for impact localization prediction. • The sensors were able to predict the location of impacts with good accuracy.

Molecular dynamics simulation of single droplet behavior on the windward side of a fiber filter during coalescence

The classical single-fiber theory has been widely used in the fiber filtration field. In order to study the behavior of droplets on fiber surface under the mechanisms (collision, interception), the process of a fiber intercepting a droplet was simplified to a droplet impacting a cylinder, which was simulated by LAMMPS. Variable diameter amorphous fibers with four contact angles were established, and the regime of impinging from spreading to break up was studied with the Reynolds number ranging from 1.17 to 11.69. The results showed that the spreading factor increases with the decrease of contact angle and the increase of fiber diameter. When the projection of the impact location deviates from the fiber center, the droplet spreading factor gradually decreases. The criterion of breakup was established by using Newton's second law based on the maximum spreading factor model, which well predicts compared to the results obtained in molecular dynamic simulations.

EV-Catcher: High-Speed Object Catching Using Low-Latency Event-Based Neural Networks

Event-based sensors have recently drawn increasing interest in robotic perception due to their lower latency, higher dynamic range, and lower bandwidth requirements compared to standard CMOS-based imagers. These properties make them ideal tools for real-time perception tasks in highly dynamic environments. In this work, we demonstrate an application where event cameras excel: accurately estimating the impact location of fast-moving objects. We introduce a lightweight event representation called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Binary Event History Image</i> (BEHI) to encode event data at low latency, as well as a learning-based approach that allows real-time inference of a confidence-enabled control signal to the robot. To validate our approach, we present an experimental catching system in which we catch fast-flying ping-pong balls. We show that the system is capable of achieving a success rate of 81% in catching balls targeted at different locations, with a velocity of up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$13\,\text{m/s}$</tex-math></inline-formula> even on compute-constrained embedded platforms such as the Nvidia Jetson NX.

On wave impact pressure variability

The variability of the largest wave impacts, where nominally identical waves produce significantly different pressures, is widely known. However, the mechanisms are not well understood. Here we provide a review and investigation of factors affecting the variability of wave impact pressures on steep walls, quantifying the range of parameters that have been used in the literature. We then present two investigations: (i) Setup 1 on the effect of structure slope and (ii) Setup 2 on the effects of kinematics variability on pressure variability. Firstly, wave impacts arising from about 250 focused wave groups interacting with three values of wall steepness (vertical, 10° to the vertical, and 27° to the vertical) showed that steeper walls resulted in larger impact loads, the largest of which were experienced higher up the wall. The maximum pressure data was seen to be a good fit to the Gumbel model for the vertical wall but closer to the log-Normal distribution for the 10° wall. Parameter estimates for those distributions revealed a systematic variation which could potentially be used to predict maximum impact pressures at intermediate wall angles and locations. The pressure wave arising from the impact was seen to be of highly variable speed, for the 10° wall it was estimated to be about 10 m/s at the 1:25 model scale, decreasing for the 27° wall. In the second investigation, which provided kinematics data using particle tracking velocimetry, rapidly varying velocities close to the impact location were observed, with maximum values at impact being a reasonable fit to the Weibull distribution. Findings indicate that though the water surface may appear to be calm, residual sub-surface velocities undoubtedly play some role in the variability of the subsequent wave impact pressures. • Impact pressure probability distributions deduced for different wall geometries. • Parameter estimates for the probability distributions revealed a systematic variation. • Wave kinematics probability distribution obtained from particle tracking velocimetry. • Coefficient of variation of wave kinematics higher than that of impact pressures.

Kumar and Daigavane's Impacted Maxillary Canine Grading System: A New Classification System For Treatment of Cleft Lip and Palate.

Introduction Maxillary canines are the most commonly impacted teeth, second only to third molars. Cleft lip and palate patients have a higher chance of impacted canines due to defects in bone formation and the soft tissue enclosing it. Various authors have used two-dimensional radiographs and developed grading systems to streamline treatment modalities to deal with the impacted canines. Material and Methods A study was conducted in the Department of Orthodontics and Dentofacial Orthopaedics. Children aged nine to 12 were selected for this evaluation based on both clinical and radiographic examination. Four different parameters were set to evaluate the impacted canine location. which was based on angulation, vertical height, root apex location, and defect area involved. Result Based on these evaluations, a classification was developed by the present authors, and later the cases were assessed as per the new system that wenamed Kumar andDaigavane's (KD) Impacted Maxillary Canine Grading System which we developedto give us more clarity for treatment and prognosis for treatment of cleft lip and palate. Conclusion A three-dimensional evaluation is also advised for a better understanding of the impacted canines. Many of the shortcomings of the two-dimensional assessment can be diminished. This new grading system will improve cleft diagnosis and prognosis in patients with cleft lips and/or palates.

A Methodology for a Coupled Structural - CFD Analysis of Compressor Rotor Blades Subjected to Ice Impact with Uncertain Impactor Parameters

Abstract A method for a coupled structural - Computational Fluid Dynamics (CFD) analysis of a compressor rotor blade subjected to an ice impact scenario is investigated to assess the impact related blade deformations from a structural and fluid-dynamics perspective. On the basis of a probabilistic approach, in total 50 impact scenarios are derived for this study. In a first step the numerical structural model based on Finite Elements (FE) is discussed, including several parameter variations like impact location, ice diameter, ice density and rotor speed. Different analysis steps are subsequently carried out using LSDYNA implicit / explicit on a high performance computing (HPC) cluster. Resulting blade deformations are evaluated in terms of local plastic deformation, cup size and modal parameters in comparison to the undamaged reference structure. The resultant post-impact blade geometry is extracted from the result data and passed to the CFD simulation setup in a fully automated manner. Based on this deformed structural mesh data, the fluid mesh is morphed via a radial basis function (RBF) approach and analysed with CFD. Finally, an uncertainty quantification study is performed to assess the variability of results with regard to the definition of the ice impactor.