Modelling and Simulation of the Hand-Arm-System During Impact Influences

2012 ◽  
Author(s):  
Sven Matthiesen ◽  
Tobias Schäfer ◽  
Sebastian Mangold
Keyword(s):  
High Speed ◽  
Mechanical Response ◽  
Reaction Force ◽  
Human Hand ◽  
Movement Velocity ◽  
Time Period ◽  
Acceleration Sensors ◽  
Impact Phase ◽  
Short Time ◽  
Two Degree Of Freedom

Most common models of hand-arm systems describe the mechanical response by low accelerations and short movements. The focus of this paper is on impacts (over 4.000 m/s2) to the human hand-arm system, in this case caused by a bolt setting device. To develop an accurate model of the hand-arm system, the force needed to be measured without to influence the interaction. Because of the very short time period it is not possible to measure the reaction force directly. To investigate the effects of different operators on the behavior of the power tool, a two-degree-of-freedom model of hand-arm-systems is developed, to predict mechanical interactions of the hand-arm-system with the power tool. Inputs for this simulation model are movement, velocity and acceleration. The motion of the device in the heavy impact phase is tracked by a high-speed camera and time-synchronized acceleration sensors. Based on this data, a robust and easy model of a hand-arm system is presented.

scholarly journals An image analysis method for determining boiling front in minichannel heat exchanger

2021 ◽  
Vol 321 ◽  
pp. 01006
Author(s):  
Gabriela Rafałko ◽  
Hubert Grzybowski ◽  
Paweł Dzienis ◽  
Romuald Mosdorf
Keyword(s):  
High Speed ◽  
Two Dimensional ◽  
Short Time Period ◽  
Analysis Method ◽  
Image Analysis Method ◽  
Time Period ◽  
Minichannel Heat Exchanger ◽  
Test Frame ◽  
X 32 ◽  
Short Time

In this work a numerical method for determining boiling front in short time period of flow was presented. A non-stationary boiling in rectangular eleven minichannels (0.25 mm x 0.25 mm x 32 mm) was recorded using Phantom v1610 high speed camera with the speed of 6000 fps. In the algorithm correlation between subsequent frames was computed. Frames were divided into reference and test frames. In each iteration a part of a reference frame called ‘reference gate’ and moving part of a test frame called ‘moving gate’ were considered. A two-dimensional correlation coefficient was calculated. Such method allowed to identify the location of boiling front in each minichannel separately.

Study on Technology System and System Integration Method of China High-Speed Railway

2010 ◽  
Author(s):  
Shuguang Zhang
Keyword(s):  
System Integration ◽  
High Speed ◽  
Large Scale ◽  
Integration Method ◽  
Low Cost ◽  
Short Time Period ◽  
High Speed Railway ◽  
Technology System ◽  
Time Period ◽  
Short Time

Since 2004, China had launched the construction of a large-scale high-speed railways network, China had developed a set of mature, reliable technology systems and system integration method for high-speed railways with relatively low cost in a comparatively short time period. The special demands for highspeed railways in china were analyzed firstly, and then the structure and characteristics of the technology system of China high-speed railways were presented, as well as the system integration method. At last, the development trends of China high-speed railway technology are proposed.

Oblique Impact of Thick Walled Pressurized Spheres as Used in Tennis

2005 ◽  
Vol 219 (11) ◽  
pp. 1179-1189 ◽  
Author(s):  
S J Haake ◽  
M J Carré ◽  
R Kirk ◽  
S R Goodwill
Keyword(s):  
Coefficient Of Friction ◽  
Momentum Flux ◽  
High Speed ◽  
Reaction Force ◽  
Oblique Impact ◽  
Tennis Ball ◽  
The Coefficient Of Friction ◽  
Impact Phase ◽  
Rotation Set ◽  
The Impact

A model is presented in which the normal impact of a thick walled pressurized sphere, such as a tennis ball, is modelled as a non-linear viscoelastic spring and damper, coupled with momentum-flux forces where the shell wall deforms with high stiffness and damping. These momentum-flux forces are only present in the impact phase and do not appear during restitution. Rotation set up during an oblique impact causes the momentum-flux forces at the front and rear of the sphere to be different such that the total vertical reaction force acts in front of the centre of mass when topspin is present. The sphere was allowed to deform and this caused both the torque and the effective moment of inertia of the sphere to decrease. The result of this is that the deformed sphere gains sufficient spin during impact for reverse slip to occur when the ball reforms towards the end of impact. Tennis balls were projected at two similarly constructed surfaces with a coefficient of friction of 0.51 and 0.62. It was found that displacements and rotations from the model compared well with experimental results recorded using a high-speed video running at 7100 frames per second. The model was able to predict these results with only the coefficient of friction as the varying parameter.

Aggregate formation of erythrocytes in postcapillary venules

2005 ◽  
Vol 288 (2) ◽  
pp. H584-H590 ◽  
Author(s):  
Sangho Kim ◽  
Aleksander S. Popel ◽  
Marcos Intaglietta ◽  
Paul C. Johnson
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Erythrocyte Aggregation ◽  
Aggregate Formation ◽  
Fixed Distance ◽  
High Speed Video Camera ◽  
Time Period ◽  
Before And After ◽  
Short Time

The purpose of the present study was to obtain information on erythrocyte aggregate formation in vivo. The movements of erythrocytes in postcapillary venules of the rat spinotrapezius muscle at various flow rates were recorded with a high-speed video camera before and after infusion of dextran 500. To distinguish aggregates, the following criteria were used: 1) a fixed distance (4 μm) between the center points of two adjacent cells, 2) lack of visible separation between the adjacent cells, and 3) movement of the adjacent cells in the same direction. Without dextran 500 infusion, 11 and 5% of erythrocytes formed aggregates in low (33.2 ± 28.3 s) and high pseudoshear (144.2 ± 58.3 s) conditions, respectively, based on the above criteria. After dextran 500 infusion, 53% of erythrocytes satisfied the criteria in the low pseudoshear condition (26.5 ± 17.0 s) and 13% of erythrocytes met the criteria in the high pseudoshear condition (240.0 ± 85.9 s), indicating erythrocyte aggregation is strongly associated with shear rate. Approximately 90% of aggregate formation occurred in a short time period (0.15–0.30 s after entering the venule) in a region 15 to 30 μm from the entrance. The time delay may reflect rheological entrance conditions in the venule.

World Economy: Prospects and Barriers for Recovery

2012 ◽  
pp. 61-83 ◽  
Author(s):  
M. Ershov
Keyword(s):  
World Economy ◽  
Western World ◽  
Short Time Period ◽  
Market Segments ◽  
Junk Bonds ◽  
The Past ◽  
Time Period ◽  
The Us ◽  
Global Liquidity ◽  
Short Time

According to the latest forecasts, it will take 10 years for the world economy to get back to “decent shape”. Some more critical estimates suggest that the whole western world will have a “colossal mess” within the next 5–10 years. Regulators of some major countries significantly and over a short time‑period changed their forecasts for the worse which means that uncertainty in the outlook for the future persists. Indeed, the intensive anti‑crisis measures have reduced the severity of the past problems, however the problems themselves have not disappeared. Moreover, some of them have become more intense — the eurocrisis, excessive debts, global liquidity glut against the backdrop of its deficit in some of market segments. As was the case prior to the crisis, derivatives and high‑risk operations with “junk” bonds grow; budget problems — “fiscal cliff” in the US — and other problems worsen. All of the above forces the regulators to take unprecedented (in their scope and nature) steps. Will they be able to tackle the problems which emerge?

Effect of short-term use of oral contraceptive pills on intraocular pressure

2020 ◽  
Vol 35 (3) ◽  
Author(s):  
Tayyaba Gul Malik ◽  
Hina Nadeem ◽  
Eiman Ayesha ◽  
Rabail Alam
Keyword(s):  
Oral Contraceptive ◽  
Childbearing Age ◽  
Short Term ◽  
Oral Contraceptive Pills ◽  
Contraceptive Pills ◽  
Time Period ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
Short Time

Objective: To study the effect of short-term use of oral contraceptive pills on intra-ocular pressures of women of childbearing age.   Methods: It was a comparative observational study, conducted at Arif memorial teaching hospital and Allied hospital Faisalabad for a period of six months. Hundred female subjects were divided into two groups of 50 each. Group A, included females, who had been taking oral contraceptive pills (OCP) for more than 6 months and less than 36 months. Group B, included 50 age-matched controls, who had never used OCP. Ophthalmic and systemic history was taken. Careful Slit lamp examination was performed and intraocular pressures (IOP) were measured using Goldman Applanation tonometer. Fundus examination was done to rule out any posterior segment disease. After collection of data, we analyzed and compared the intra ocular pressures between the two groups by using ANOVA in SPSS version 21.   Results: Average duration of using OCP was 14.9 months. There was no significant difference of Cup to Disc ratios between the two groups (p= 0.109). However, significant difference was noted between the IOP of OCP group and controls. (p=0.000). Conclusion: OCP significantly increase IOP even when used for short time period.

scholarly journals Neuro-Inspired Computing with Spin-VCSELs

2021 ◽  
Vol 11 (9) ◽  
pp. 4232
Author(s):  
Krishan Harkhoe ◽  
Guy Verschaffelt ◽  
Guy Van der Sande
Keyword(s):  
Processing Speed ◽  
Delay Time ◽  
High Speed ◽  
State Of The Art ◽  
Polarization Modulation ◽  
Time Interval ◽  
Computing Technique ◽  
High Modulation ◽  
Short Time ◽  
Modulation Speed

Delay-based reservoir computing (RC), a neuromorphic computing technique, has gathered lots of interest, as it promises compact and high-speed RC implementations. To further boost the computing speeds, we introduce and study an RC setup based on spin-VCSELs, thereby exploiting the high polarization modulation speed inherent to these lasers. Based on numerical simulations, we benchmarked this setup against state-of-the-art delay-based RC systems and its parameter space was analyzed for optimal performance. The high modulation speed enabled us to have more virtual nodes in a shorter time interval. However, we found that at these short time scales, the delay time and feedback rate heavily influence the nonlinear dynamics. Therefore, and contrary to other laser-based RC systems, the delay time has to be optimized in order to obtain good RC performances. We achieved state-of-the-art performances on a benchmark timeseries prediction task. This spin-VCSEL-based RC system shows a ten-fold improvement in processing speed, which can further be enhanced in a straightforward way by increasing the birefringence of the VCSEL chip.

scholarly journals Political ideology and vaccination willingness: implications for policy design

2021 ◽  
Author(s):  
Marc Debus ◽  
Jale Tosun
Keyword(s):  
Side Effects ◽  
Political Ideology ◽  
Policy Design ◽  
Public Support ◽  
Individual Freedom ◽  
Short Time Period ◽  
Successful Development ◽  
Individual Level ◽  
Time Period ◽  
Short Time

AbstractThe COVID-19 pandemic has forced governments to impose major restrictions on individual freedom in order to stop the spread of the virus. With the successful development of a vaccine, these restrictions are likely to become obsolete—on the condition that people get vaccinated. However, parts of the population have reservations against vaccination. While this is not a recent phenomenon, it might prove a critical one in the context of current attempts to manage the COVID-19 pandemic. Consequently, the task of designing policies suitable for attaining high levels of vaccination deserves enhanced attention. In this study, we use data from the Eurobarometer survey fielded in March 2019. They show that 39% of Europeans consider vaccines to cause the diseases which they should protect against, that 50% believe vaccines have serious side effects, that 32% think that vaccines weaken the immune system, and that 10% do not believe vaccines are tested rigorously before authorization. We find that—even when controlling for important individual-level factors—ideological extremism on both ends of the spectrum explains skepticism of vaccination. We conclude that policymakers must either politicize the issue or form broad alliances among parties and societal groups in order to increase trust in and public support for the vaccines in general and for vaccines against COVID-19 in particular, since the latter were developed in a very short time period and resulted—in particular in case of the AstraZeneca vaccine—in reservations because of the effectiveness and side effects of the new vaccines.

scholarly journals Platypnoea–orthodeoxia syndrome induced by short-term weight loss: a case series

2020 ◽  
Author(s):  
Yudai Tamura ◽  
Tomohiro Sakamoto
Keyword(s):  
Weight Loss ◽  
Septal Defect ◽  
Case Series ◽  
Transoesophageal Echocardiography ◽  
Sitting Position ◽  
Short Time Period ◽  
Time Period ◽  
Uncommon Condition ◽  
The Right ◽  
Short Time

Abstract Background Platypnoea–orthodeoxia syndrome (POS) is an uncommon condition characterized by dyspnoea and arterial desaturation in the standing or sitting position that improves in the supine position. Case summary We report two cases of POS caused by an atrial septal defect (ASD) and a patent foramen ovale (PFO). Both cases reported a recent decrease in body weight of more than 10 kg in a short time period. Transoesophageal echocardiography (TOE) with agitated saline bubble study revealed and a large amount of contrast bubble through the ASD (Patient 1) or the PFO (Patient 2) from the right atrium to the left atrium in the sitting position. Both patients were diagnosed by the finding of positional dyspnoea and the results of TOE using agitated saline bubble contrast. Discussion Taken together, their presentations suggest that weight loss in a short time period could be a pathogenic factor for POS.

scholarly journals Acute Effects of Handheld Loading on Standing Broad Jump in Youth Athletes

2021 ◽  
Vol 18 (9) ◽  
pp. 5046
Author(s):  
Wei-Hsun Tai ◽  
Ray-Hsien Tang ◽  
Chen-Fu Huang ◽  
Shin-Liang Lo ◽  
Yu-Chi Sung ◽  
...  
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sampling Rate ◽  
Random Order ◽  
Horizontal Distance ◽  
Acute Effects ◽  
Vertical Ground Reaction Force ◽  
Strength And Conditioning ◽  
Peak Knee

The study aimed to investigate the acute effects of handheld loading on standing broad jump (SBJ) performance and biomechanics. Fifteen youth male athletes (mean age: 14.7 ± 0.9 years; body mass: 59.3 ± 8.0 kg; height: 1.73 ± 0.07 m) volunteered to participate in the study. Participants were assigned to perform SBJ with and without 4 kg dumbbells in a random order. Kinematic and kinetic data were collected using 10 infrared high-speed motion-capture cameras at a 250 Hz sampling rate and two force platforms at a 1000 Hz sampling rate. A paired t-test was applied to all variables to determine the significance between loading and unloading SBJs. Horizontal distance (p < 0.001), take-off distance (p = 0.001), landing distance (p < 0.001), horizontal velocity of center of mass (CoM; p < 0.001), push time (p < 0.001), vertical impulse (p = 0.003), and peak horizontal and vertical ground reaction force (GRF; p < 0.001, p = 0.017) were significantly greater in loading SBJ than in unloading SBJ. The take-off vertical velocity of CoM (p = 0.001), take-off angle (p < 0.001), peak knee and hip velocity (p < 0.001, p = 0.007), peak ankle and hip moment (p = 0.006, p = 0.011), and peak hip power (p = 0.014) were significantly greater in unloading SBJ than in loading SBJ. Conclusions: Acute enhancement in SBJ performance was observed with handheld loading. The present findings contribute to the understanding of biomechanical differences in SBJ performance with handheld loading and are highly applicable to strength and conditioning training for athletes.

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