Effect of Body Flexibility on Impacts Studied on Rods and Beams

2007 ◽  
Author(s):  
Robert Seifried
Keyword(s):  
Nonlinear Behavior ◽  
Coefficient Of Restitution ◽  
Short Time Period ◽  
Structural Vibrations ◽  
Bending Vibrations ◽  
Time Period ◽  
Highly Nonlinear ◽  
Contact Models ◽  
Short Time ◽  
The Impact

The effect of body flexibility on the impact process is studied through longitudinal impacts on rods and transverse impacts on beams. An experimental setup is presented using Laser-Doppler-Vibrometers in order to measure the displacement and velocity of the colliding bodies during impact. For the numerical investigation, modally-reduced models are used in combination with local Finite Element contact models. Performed on a microscale, these experimental and numerical investigations yield a good understanding of the effect of flexibility influencing the impact, and therefore, the coefficient of restitution. The investigations show that impacts of steel spheres on rods and beams yield strong structural vibrations. In the case of the rod impacts, the coefficient of restitution decreases monotonically with increasing initial velocity. In the case of the beams, the strong bending vibrations which are initiated, cause multiple successive impacts within a very short time period. This results in highly nonlinear behavior and uncertainty for the coefficient of restitution.

The Response Characteristics of Various Impact Patterns on the Smart Bumper of Automotives

2009 ◽  
Vol 413-414 ◽  
pp. 181-187
Author(s):  
Yong Hong ◽  
Gao Ping Wang ◽  
Yeon Gon Go ◽  
Dong Pyo Hong ◽  
Tae Jin Chung
Keyword(s):  
Impact Analysis ◽  
Smart Sensors ◽  
Short Time Period ◽  
Pendulum System ◽  
Response Characteristics ◽  
Time Period ◽  
Fundamental Research ◽  
Analysis System ◽  
Short Time ◽  
The Impact

In this paper, a pendulum system is constructed to perform the fundamental research which is concentrated on the various frequency patterns of impact-object simulation tests. We confirmed the application possibility for the method of discriminable pattern recognition whether impact-object is human-like or not via frequency analysis using smart sensors. Therefore a specific experimental data are compared and analyzed with the obtained database within a short time period. The impact analysis system, which is based on the above processing, can be developed and then used to recognize the impact information measured by smart sensors.

Management of invasive mesopredators in the Flinders Ranges, South Australia: effectiveness and implications

2020 ◽  
Vol 47 (8) ◽  
pp. 720
Author(s):  
Alyson M. Stobo-Wilson ◽  
Robert Brandle ◽  
Christopher N. Johnson ◽  
Menna E. Jones
Keyword(s):  
Prey Species ◽  
South Australia ◽  
Short Time Period ◽  
Short Term ◽  
Feral Cat ◽  
Feral Cats ◽  
Flinders Ranges ◽  
Time Period ◽  
Short Time ◽  
The Impact

Abstract ContextSignificant resources have been devoted to the control of introduced mesopredators in Australia. However, the control or removal of one pest species, such as, for example, the red fox (Vulpes vulpes), may inadvertently benefit other invasive species, namely feral cats (Felis catus) and rabbits (Oryctolagus cuniculus), potentially jeopardising native-species recovery. AimsTo (1) investigate the impact of a large-scale, long-term fox-baiting program on the abundance of foxes, feral cats and introduced and native prey species in the Flinders Ranges, South Australia, and (2) determine the effectiveness of a short time period of cat removal in immediately reducing feral cat abundance where foxes are absent. MethodsWe conducted an initial camera-trap survey in fox-baited and unbaited sites in the Flinders Ranges, to quantify the impact of fox baiting on the relative abundance of foxes, feral cats and their prey. We then conducted a secondary survey in sites where foxes were absent, following an intensive, but short, time period of cat removal, in which 40 cats were shot and killed. Key resultsNo foxes were detected within baited sites, but were frequently detected in unbaited sites. We found a corresponding and significant increase in several native prey species in fox-baited sites where foxes were absent. Feral cats and rabbits were also more frequently detected within baited sites, but fox baiting did not singularly predict the abundance of either species. Rather, feral cats were less abundant in open habitat where foxes were present (unbaited), and rabbits were more abundant within one predominantly open-habitat site, where foxes were absent (fox-baited). We found no effect of short-term cat removal in reducing the local abundance of feral cats. In both camera-trap surveys, feral cat detections were positively associated with rabbits. ConclusionsLong-term fox baiting was effective in fox removal and was associated with a greater abundance of native and introduced prey species in the Flinders Ranges. To continue to recover and conserve regional biodiversity, effective cat control is required. ImplicationsOur study showed fox removal has likely resulted in the local release of rabbits and an associated increase in cats. Because feral cat abundance seemingly fluctuated with rabbits, we suggest rabbit control may provide an alternative and more effective means to reduce local feral cat populations than short-term removal programs.

scholarly journals COMMENTS ON “AN EMPIRICAL ASSESSMENT OF THE EMPLOYEE FREE CHOICE ACT: THE ECONOMIC IMPLICATIONS.” BY ANN LAYNE-FARRAR

Just Labour ◽  
1969 ◽  
Author(s):  
Susan Johnson
Keyword(s):  
Free Choice ◽  
Short Time Period ◽  
Public Attention ◽  
Economic Implications ◽  
Empirical Assessment ◽  
Time Period ◽  
Population Ratio ◽  
Short Time ◽  
The Impact ◽  
The Empirical Analysis

“An Empirical Assessment of the Employee Free Choice Act: TheEconomic Implications” by Ann Layne-Farrar providesempirical evidenceconcerning the impact on the U.S. unemployment rateand employment-to-population ratio should the highly controversial Employee Free Choice Act(EFCA) become law. The paper has received widespread public attention and itsanalysis is being used in the debate surrounding the EFCA. This commentaryraises three important questions about the empirical analysis: Are the predictionspresented in the study, concerning the effects of the EFCA, realistic? Is theresearch design likely to identify the effects of the EFCA? Why do the data usedin the analysis cover such a short time period? Thediscussion suggests theempirical results presented in Layne-Farrar (2009)should be viewed withconsiderable skepticism.

scholarly journals EU:s sammanhållningspolitik och regionala skillnader 2006–2016

Terra ◽  
2020 ◽  
Vol 132 (4) ◽  
pp. 175-189
Author(s):  
Daniel Rauhut ◽  
Nuno Costa
Keyword(s):  
Central Europe ◽  
Short Time Period ◽  
Cohesion Policy ◽  
Negative Effects ◽  
Positive Effects ◽  
Time Period ◽  
Methodological Approaches ◽  
Short Time ◽  
The Impact ◽  
The Eu

The effects of the EU Cohesion Policy are debated, and while some studies find positive effects, others point to negative effects. Many of the methodological approaches that have so far been used to measure the EU Cohesion Policy are simple benchmarking exercises, focusing on a few indicators covering a short time period. Other evaluations are fragmented, qualitative in nature, and narrow in scope. This paper aims at analysing the EU Cohesion Policy and its impact for the period 2006–2016. We construct a Territorial Cohesion Development Index with target posts in order to analyse the impact at a NUTS2 level. The findings indicate that bigger cities and highly urbanised regions in Central Europe benefited the most from the policy, while non-core and peripheral regions fell further behind.

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?

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.

SIMULATION OF DYNAMIC EVENT OF IMPACT USING EXPLICIT 3D FEM MODEL AND VALIDATION BY EXPERIMENT AND CONTACT MODELS

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Akshay Mallikarjuna ◽  
Dan Marghitu ◽  
P.K. Raju
Keyword(s):  
Material Properties ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Impact Behavior ◽  
3D Fem ◽  
Dynamic Event ◽  
Contact Models ◽  
Explicit Dynamic ◽  
The Impact

— In this study, an optimized method to simulate the dynamic 3D event of the impact of a rod with a flat surface has been presented. Unlike the 2D FEM based contact models, in this study both the bodies undergoing the impact are considered elastic(deformable) and simulation is the dynamic event of the impact, instead of predefined 2D symmetric contact analysis. Prominent contact models and plasticity models to define material properties in ANSYS are reviewed. Experimentation results of normal and oblique impact of the rod for different rods provided the coefficient of restitution. Experimental results of permanent deformation on the base for different impact velocity is derived out of a prominent impact study. The simulation results are in co-relation with experiment and both indentation and flattening models on the coefficient of restitution (COR) and permanent deformation of the base and rod after the impact. Thus, the presented 3D Explicit Dynamic simulation of impact is validated to analyze the impact behavior of the 2 bodies without any predefined assumptions with respect to boundary conditions or material properties.

scholarly journals Estimation of three-dimensional crustal movements in the 2011 Tohoku-oki, Japan earthquake from TerraSAR-X intensity images

2014 ◽  
Vol 2 (12) ◽  
pp. 7383-7408
Author(s):  
W. Liu ◽  
F. Yamazaki ◽  
M. Matsuoka ◽  
T. Nonaka ◽  
T. Sasagawa
Keyword(s):  
Three Dimensional ◽  
Short Time Period ◽  
Sar Images ◽  
Crustal Movements ◽  
Surface Displacements ◽  
Time Period ◽  
Intensity Images ◽  
Short Time ◽  
The Relationship ◽  
Gps Observations

Abstract. The Tohoku-Oki earthquake on 11 March 2011 caused significant widespread crustal movements. In a previous study, we proposed a method for capturing two-dimensional (2-D) surface displacements from a pair of pre- and post-event TerraSAR-X (TSX) intensity images. However, it is difficult to detect three-dimensional (3-D) displacements from one pair of TSX images. In this study, three pairs of pre- and post-event TSX images taken on different paths were used to estimate 3-D crustal movements. The relationship between the actual 3-D displacements and the converted 2-D movements in the SAR images was derived based on the observation model of a SAR sensor. The 3-D movements were then calculated from three sets of detected 2-D movements that occurred within a short time period. Compared with GPS observations, the proposed method was found to be capable of detecting the 3-D crustal movements with sub-pixel accuracy.

scholarly journals Changing Attitudes Towards Territorial Municipal Reforms – The Case of Inland Norway

2020 ◽  
Vol 18 (2) ◽  
pp. 271-292
Author(s):  
Ulla Higdem ◽  
Hans Christian Høyer ◽  
Erik Neslein Mønness ◽  
Jon Helge Lesjø
Keyword(s):  
Economic Development ◽  
National Government ◽  
Short Time Period ◽  
Time Period ◽  
Catch Up ◽  
Changing Attitudes ◽  
Short Time ◽  
Citizens Attitudes ◽  
Municipal Reforms

Inland people’s attitude towards municipal amalgamation reform in Norway from 2013 to 2018 has become more positive. However, a majority does not support the ongoing reform, but the changes have been substantial during such a short time period. However, these changes seem not to be a result of new and more positive judgements of the reforms’ results and outcome. By contrast, the majority has been more critical of anticipated consequences of the amalgamation reform into larger municipalities. Instead, we considered the changes as a type of ‘resignation’ towards a reform pressure from the national government and general changes in their environment. More citizens’ assess that positive municipal economic development and more local competence are favourable effects of mergers, and this finding supports this claim. The reform is likely to catch up with their local units anyway, and the citizens’ attitudes are adapting to what they expect will occur in the upcoming years.

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