scholarly journals Analyzing the Effect of Temperature on Squash Ball Impacts Using High-Speed Camera Recordings

2021 ◽  
Author(s):  
Bence Ferenc Berencsi ◽  
Attila Kossa
Keyword(s):  
High Speed ◽  
Elevated Temperatures ◽  
Primary Objective ◽  
Effect Of Temperature ◽  
High Speed Camera ◽  
Compression Tests ◽  
Low Velocity ◽  
Different Types ◽  
Dynamical Parameters ◽  
The Impact

Description of the impact characteristics of different types of balls has a great importance in sport science and in engineering. The primary objective of the present paper is to investigate the effect of the temperature on the impacts of different types of squash balls from a given company. The shots were performed using a self-built air-cannon. The impacts were recorded by a high-speed camera and the recorded videos were analyzed by an image-processing method based on a background subtraction technique. Summarizing the main dynamical parameters, we can conclude that increasing the initial speed will decrease the contact time, the coefficient of restitution (COR) and the rebound resilience, whereas these parameters increase at elevated temperatures. The compression tests revealed that within the low velocity range the deformation of the ball’s material and not the compression of the inner gas is the main contribution in the force needed to compress the ball. However, when the ball suffers large deformations, the internal air pressure has a huge effect on the rebound behavior. The measurements revealed that there is an optimal initial velocity distinct from the maximum one where the rebound velocity of the ball is higher than in all other cases. From the results we can state that the ball's overall stiffness grows as the temperature increases.

Rate Dependent Material Model for Helmet Pads

2020 ◽  
Author(s):  
Timothy G. Zhang ◽  
A. H. Fulton ◽  
K. Ravi-Chandar ◽  
Sikhanda S. Satapathy
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
High Speed ◽  
Material Model ◽  
High Speed Camera ◽  
Low Velocity ◽  
Rate Dependent ◽  
Military Helmet ◽  
The Impact ◽  
Impact Experiments

Abstract Foam pads are commonly used in sports and military helmet for energy absorption, form-fitting and comfort. Both for low velocity and high velocity applications, their rate-dependent mechanical properties need to be characterized to understand their ability to effectively modulate the transmitted stress pulse. Impact experiments were conducted on bilayer helmet pads at a range of velocities covering low to medium rates up to ∼7000/s. Images from high-speed camera were used to construct x-T diagrams to measure the shock speeds from the impact experiments. Numerical simulations were carried out to validate a foam pad model and to understand experimental uncertainties. The scatter in the measured shock speeds was found to be related to the scatter in the material properties.

The Calibration of High Energy-Rate Impact Forging Hammers by the Copper-Column Upsetting Method and High Speed Camera Measurements

2014 ◽  
Vol 611-612 ◽  
pp. 173-177 ◽  
Author(s):  
Lander Galdos ◽  
Eneko Sáenz de Argandoña ◽  
Nuria Herrero ◽  
Mikel Ongay ◽  
Julen Adanez ◽  
...  
Keyword(s):  
High Speed ◽  
Low Cycle Fatigue ◽  
High Energy ◽  
Important Variable ◽  
Fatigue Properties ◽  
High Speed Camera ◽  
Compression Tests ◽  
High Energy Rate ◽  
The Impact ◽  
Copper Column

The hammer forging is a well-known technology to incrementally produce geometrically complex forgings by compressing the material against the dies using several forming blows. When forging aeronautical components with this technology, it is crucial to control the final grain size of the part since this variable highly influences the high temperature low cycle fatigue properties. Nowadays, it is common practice to use the finite element models coupled with recrystallization models to optimize the process parameters and strategy. However, a very important variable to conduct these simulations is the real available hammer energy, which must be calibrated, not being an easy task since very high forces are generated in the impact of the anvils. In the present paper, the copper-column upsetting method is compared with a novel method where a high speed camera has been used to compute the anvils’ velocity and corresponding energies. The compressive behavior of the copper samples has been characterized using Rastegaev compression tests. The experimental and calculated results using the high speed camera are compared to the ones obtained using high purity copper samples. These measurements have enable to quantify the influence the friction and the elastic rebound have during the energy transfer from the anvils to the billet. This makes possible a precise future characterization of hammers using the conventional copper-column upsetting method if high speed cameras are not available in workshop.

scholarly journals Does the Opening of High-Speed Railway Lines Reduce the Carbon Intensity of China’s Resource-Based Cities?

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4648
Author(s):  
Zhipeng Tang ◽  
Ziao Mei ◽  
Jialing Zou
Keyword(s):  
High Speed ◽  
National Average ◽  
Carbon Intensity ◽  
Time Varying ◽  
Low Carbon ◽  
High Speed Railway ◽  
Different Types ◽  
Endogenous Selection ◽  
Mode Of Development ◽  
The Impact

The carbon intensity of China’s resource-based cities (RBCs) is much higher than the national average due to their relatively intensive mode of development. Low carbon transformation of RBCs is an important way to achieve the goal of reaching the carbon emissions peak in 2030. Based on the panel data from 116 RBCs in China from 2003 to 2018, this study takes the opening of high-speed railway (HSR) lines as a quasi-experiment, using a time-varying difference-in-difference (DID) model to empirically evaluate the impact of an HSR line on reducing the carbon intensity of RBCs. The results show that the opening of an HSR line can reduce the carbon intensity of RBCs, and this was still true after considering the possibility of problems with endogenous selection bias and after applying the relevant robustness tests. The opening of an HSR line is found to have a significant reducing effect on the carbon intensity of different types of RBC, and the decline in the carbon intensity of coal-based cities is found to be the greatest. Promoting migration of RBCs with HSR lines is found to be an effective intermediary way of reducing their carbon intensity.

Experimental investigation of the quasi-static and impact tests on the energy absorption characteristics of coupler rubber buffers used in railway vehicles

2018 ◽  
Vol 233 (9) ◽  
pp. 937-950 ◽  
Author(s):  
Shuguang Yao ◽  
Zhixiang Li ◽  
Wen Ma ◽  
Ping Xu ◽  
Quanwei Che
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
High Speed ◽  
Compression Tests ◽  
Static Compression ◽  
Static Tests ◽  
Impact Tests ◽  
High Speed Trains ◽  
The Impact ◽  
Absorption Characteristics

Coupler rubber buffers are widely used in high-speed trains, to dissipate the impact energy between vehicles. The rubber buffer consists of two groups of rubbers, which are pre-compressed and then installed into the frame body. This paper specifically focuses on the energy absorption characteristics of the rubber buffers. Firstly, quasi-static compression tests were carried out for one and three pairs of rubber sheets, and the relationship between the energy absorption responses, i.e. Eabn  =  n ×  Eab1, Edissn =  n ×  Ediss1, and Ean =  Ea1, was obtained. Next, a series of quasi-static tests were performed for one pair of rubber sheet to investigate the energy absorption performance with different compression ratios of the rubber buffers. Then, impact tests with five impact velocities were conducted, and the coupler knuckle was destroyed when the impact velocity was 10.807 km/h. The results of the impact tests showed that with the increase of the impact velocity, the Eab, Ediss, and Ea of the rear buffer increased significantly, but the three responses of the front buffer did not increase much. Finally, the results of the impact tests and quasi-static tests were contrastively analyzed, which showed that with the increase of the stroke, the values of Eab, Ediss, and Ea increased. However, the increasing rates of the impact tests were higher than that of the quasi-static tests. The maximum value of Ea was 68.76% in the impact tests, which was relatively a high value for the vehicle coupler buffer. The energy capacity of the rear buffer for dynamic loading was determined as 22.98 kJ.

scholarly journals Experimental investigation of the impact response of novel steelbiocomposite hybrid materials

2018 ◽  
Vol 183 ◽  
pp. 02040
Author(s):  
KarthikRam Ramakrishnan ◽  
Mikko Hokka ◽  
Essi Sarlin ◽  
Mikko Kanerva ◽  
Reijo Kouhia ◽  
...  
Keyword(s):  
High Speed ◽  
Structural Integrity ◽  
Metal Layer ◽  
Rear Surface ◽  
Impact Resistance ◽  
Natural Fibre ◽  
Image Correlation ◽  
Impact Response ◽  
High Speed Camera ◽  
The Impact

Recent developments in the production of technical flax fabrics allow the use of sustainable natural fibres to replace synthetic fibres in the manufacture of structural composite parts. Natural fibre reinforced biocomposites have been proven to satisfy design and structural integrity requirements but impact strength has been identified as one of their limitations. In this paper, hybridisation of the biocomposite with a metal layer has been investigated as a potential method to improve the impact resistance of natural fibre composites. The impact response of biocomposites made of flax-epoxy is investigated experimentally using a high velocity particle impactor. A high-speed camera setup was used to observe the rear surface of the plates during impact. Digital Image Correlation (DIC) of the high speed camera images was used for full-field strain measurement and to study the initiation and propagation of damage during the impact. The different modes of damage in the hybrid laminate were identified by postimpact analysis of the section of the damaged composite plate using optical microscopy. The study shows the difference in impact response for different material combinations and configurations. The hybrid construction was shown to improve the impact resistance of the flax composite.

scholarly journals Experimental heatwaves negatively impact sperm quality in the zebra finch

2018 ◽  
Vol 285 (1871) ◽  
pp. 20172547 ◽  
Author(s):  
Laura L. Hurley ◽  
Callum S. McDiarmid ◽  
Christopher R. Friesen ◽  
Simon C. Griffith ◽  
Melissah Rowe
Keyword(s):  
Male Fertility ◽  
Elevated Temperatures ◽  
Sperm Quality ◽  
Recovery Period ◽  
Heat Exposure ◽  
Effect Of Temperature ◽  
Normal Morphology ◽  
Warming World ◽  
The Impact

For sexually reproducing species, functionally competent sperm are critical to reproduction. While high atmospheric temperatures are known to influence the timing of breeding, incubation and reproductive success in birds, the effect of temperature on sperm quality remains largely unexplored. Here, we experimentally investigated the impact of ecologically relevant extreme temperatures on cloacal temperature and sperm morphology and motility in zebra finches Taeniopygia guttata . We periodically sampled males exposed to 30°C or 40°C temperatures daily for 14 consecutive days. Following a 12-day (23°C) recovery period, birds were again exposed to heat, but under the alternate treatment (e.g. birds initially exposed to 40°C were exposed to 30°C). Elevated temperatures led to an increase in cloacal temperature and a reduction in the proportion of sperm with normal morphology; these effects were most notable under 40°C conditions, and were influenced by the duration of heat exposure and prior exposure to high temperature. Our findings highlight the potential role of temperature in determining male fertility in birds, and perhaps also in constraining the timing of avian breeding. Given the increased frequency of heatwaves in a warming world, our results suggest the need for further work on climatic influences on sperm quality and male fertility.

Experimental Study on the Response Characteristics of Oilcans under High-Velocity Fragment Impact

2012 ◽  
Vol 510 ◽  
pp. 500-506
Author(s):  
Chang Hai Chen ◽  
Xi Zhu ◽  
Hai Liang Hou ◽  
Li Jun Zhang ◽  
Ting Tang
Keyword(s):  
Experimental Study ◽  
High Velocity ◽  
High Speed ◽  
Room Temperature ◽  
Experimental Results ◽  
Fuel Oil ◽  
High Speed Camera ◽  
Response Characteristics ◽  
Fuel Oils ◽  
The Impact

To explore the deflagration possibility of the warship cabin filled with fuel oil under impact of high-speed fragments in the condition of room temperature, experiments were carried out employing the small aluminium oilcans filled with fuel oil. Response processes of the oilcans were observed with the help of a high-speed camera. The disintegration as well as flying scattering of the oilcans were analyzed. The reasons for atomization of the fuel oils were presented. Finally, the deflagration possibility of warship oil cabin was analyzed. Results show that the pressure inside the oilcan is quite great under the impact of the high-speed fragment, which makes the oilcan disintegration and flying scattering. Simultaneously, fuel oils inside the oilcans are atomized quickly followed by ejected in front and back directions. Under the same condition as in present tests, deflagration will not occur for fuel oils used by warships. Experimental results will provide valuable references for the deflagration analysis of warship fuel oil cabins subjected to the impact of high-velocity fragments.

scholarly journals Cavitation Flow of Oil and Water Through the Nozzle

2020 ◽  
Vol 328 ◽  
pp. 03012
Author(s):  
Marian Bojko ◽  
Milada Kozubková ◽  
Jana Jablonská
Keyword(s):  
High Speed ◽  
Cavitation Number ◽  
Loss Coefficient ◽  
High Speed Camera ◽  
Cavitation Flow ◽  
Air Content ◽  
Hydraulic Equipment ◽  
Hydraulic Fluids ◽  
Different Types ◽  
Different Temperatures

The hydraulic equipment and elements are designed so that the flow is not significantly affected by the content of gases in the fluid. In the case of cavitation, there is a change in the volumetric amount of gas, which in water is due to the air and water vapour present, and in the case of oils, especially the air content. This phenomenon causes a significant change in the loss coefficient of the element. The problem of cavitation is solved in the literature for water flow, for other hydraulic fluids (e.g. hydraulic oils operated at different temperatures) the problem is still not solved to a sufficient extent. The article deals with the issue of cavitation in systems in which different types of liquids are used. In the introduction, the physical properties of the used liquids are evaluated, because they significantly influence the origin and development of cavitation. Subsequently, an experimental device with a transparent nozzle is described, on which the measurement. The dependence of the loss coefficient and the cavitation number on the Reynolds number is evaluated. Cavitation is evaluated by a high-speed camera, where it is possible to monitor the behaviour of the cavitation cloud.

scholarly journals Investigation of Er:YAG laser-activated irrigation for the removal of biofilm and observations of laser-induced cavitation behavior

2022 ◽  
Author(s):  
Taiji Nagahashi ◽  
Yoshio Yahata ◽  
Keisuke Handa ◽  
Masato Nakano ◽  
Shigeto Suzuki ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Root Canal ◽  
High Speed ◽  
Er:Yag Laser ◽  
Positive Control ◽  
High Speed Camera ◽  
Pulp Chamber ◽  
Root Canal Irrigation ◽  
Biofilm Removal ◽  
The Impact

Abstract Background We investigated the biofilm removal effects of LAI using a pig model, focusing on the impact of the fiber tip position, and used a high-speed camera to observe the occurrence and positioning of the cavitation associated with laser irradiation. Methods A total of 16 roots of deciduous mandibular second premolars from 4 pigs were used. After a pulpectomy, the canals were left open for two weeks and sealed for 4 weeks to induce intraradicular biofilm. Then, root canal irrigation was performed with Er:YAG laser activation. The fiber tip was inserted at two different positions, i.e., into the root canal in the intracanal LAI group and into the pulp chamber in the coronal LAI group. Intracanal needle irrigation with saline or 5% NaOCl was utilized in the positive control and CNI groups. SEM and qPCR were carried out to evaluate treatment efficacy. For qPCR, ANOVA and a Tukey-Kramer post hoc test were performed with α = 0.05. A high-speed camera was used to observe the generation of cavitation bubbles and the movement of the induced bubbles after laser irradiation. Results The intracanal and coronal LAI groups showed significantly lower amounts of bacteria than either the positive control or CNI groups. There was no significant difference found between the intracanal and coronal LAI groups. SEM images revealed opened dentinal tubules with the destruction of biofilm in both LAI groups. High-speed camera images demonstrated cavitation bubble production inside the root canal after a single pulse irradiation pulse. The generated bubbles moved throughout the entire internal multi-rooted tooth space. Conclusions Coronal LAI can generate cavitation in the root canal with a simply placed fiber inside the pulp chamber, leading to effective biofilm removal. This method could thus contribute to the future development of endodontic treatments for refractory apical periodontitis caused by intraradicular biofilm.

scholarly journals Hot Summers: Effect of Extreme Temperatures on Ozone in Sydney, Australia

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 466 ◽  
Author(s):  
Steven Utembe ◽  
Peter Rayner ◽  
Jeremy Silver ◽  
Elise-Andree Guérette ◽  
Jenny Fisher ◽  
...  
Keyword(s):  
Air Quality ◽  
Elevated Temperatures ◽  
Reaction Rates ◽  
Extreme Heat ◽  
Effect Of Temperature ◽  
Biogenic Emissions ◽  
Hot Weather ◽  
Ozone Episodes ◽  
The Impact ◽  
Averaged Model

Poor air quality is often associated with hot weather, but the quantitative attribution of high temperatures on air quality remains unclear. In this study, the effect of elevated temperatures on air quality is investigated in Greater Sydney using January 2013, a period of extreme heat during which temperatures at times exceeded 40 ∘ C, as a case study. Using observations from 17 measurement sites and the Weather Research and Forecasting Chemistry (WRF-Chem) model, we analyse the effect of elevated temperatures on ozone in Sydney by running a number of sensitivity studies in which: (1) the model is run with biogenic emissions generated by MEGAN and separately run with monthly average Model of Emissions of Gases and Aerosols from Nature ( MEGAN) biogenic emissions (for January 2013); (2) the model results from the standard run are compared with those in which average temperatures (for January 2013) are only applied to the chemistry; (3) the model is run using both averaged biogenic emissions and temperatures; and (4 and 5) the model is run with half and zero biogenic emissions. The results show that the impact on simulated ozone through the effect of temperature on reaction rates is similar to the impact via the effect of temperature on biogenic emissions and the relative impacts are largely additive when compared to the run in which both are averaged. When averaged across 17 sites in Greater Sydney, the differences between ozone simulated under standard and averaged model conditions are as high as 16 ppbv. Removing biogenic emissions in the model has the effect of removing all simulated ozone episodes during extreme heat periods, highlighting the important role of biogenic emissions in Australia, where Eucalypts are a key biogenic source.

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