Quasi-Static Assessment of Response to Slamming Impact on Free Fall Lifeboats

2015 ◽  
Author(s):  
Svein Erling Heggelund ◽  
Zhiyuan Li ◽  
Beom-Seon Jang ◽  
Jonas W. Ringsberg
Keyword(s):  
Beam Theory ◽  
Free Fall ◽  
Calculation Model ◽  
Theory Approach ◽  
Design Assessment ◽  
Static Assessment ◽  
Non Linear ◽  
The Impact ◽  
Stiffened Steel ◽  
Linear Geometry

Design against impact loads (slamming) can be challenging and time consuming and can involve complex calculations. Application of simplified, quasi-static calculation approaches will make the design process much easier. In this paper, such simplified methods are discussed using free fall lifeboats as a case. Results from non-linear FE-analysis show that the response is non-linear due to large deformations. The impact pressure is then mainly carried by membrane stress and the dynamic response is small. A non-linear beam theory approach for hand calculation is established. As the non-linear calculation model is the most realistic, it is recommended that this is used in an initial design assessment. Although the results are on the conservative side, simple hand calculations including non-linear geometry can be used to predict the maximum strain. Linear methods are also investigated. However, these methods should be used with more rigid structures such as stiffened steel and aluminium panels.

First and Second Order Elastoplastic Analyses of Thin-Walled Metal Members using Generalized Beam Theory

2018 ◽  
Author(s):  
Miguel Abambres
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cross Section ◽  
Beam Theory ◽  
Second Order ◽  
Flow Rule ◽  
Non Linear ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalized Beam Theory

Original Generalized Beam Theory (GBT) formulations for elastoplastic first and second order (postbuckling) analyses of thin-walled members are proposed, based on the J2 theory with associated flow rule, and valid for (i) arbitrary residual stress and geometric imperfection distributions, (ii) non-linear isotropic materials (e.g., carbon/stainless steel), and (iii) arbitrary deformation patterns (e.g., global, local, distortional, shear). The cross-section analysis is based on the formulation by Silva (2013), but adopts five types of nodal degrees of freedom (d.o.f.) – one of them (warping rotation) is an innovation of present work and allows the use of cubic polynomials (instead of linear functions) to approximate the warping profiles in each sub-plate. The formulations are validated by presenting various illustrative examples involving beams and columns characterized by several cross-section types (open, closed, (un) branched), materials (bi-linear or non-linear – e.g., stainless steel) and boundary conditions. The GBT results (equilibrium paths, stress/displacement distributions and collapse mechanisms) are validated by comparison with those obtained from shell finite element analyses. It is observed that the results are globally very similar with only 9% and 21% (1st and 2nd order) of the d.o.f. numbers required by the shell finite element models. Moreover, the GBT unique modal nature is highlighted by means of modal participation diagrams and amplitude functions, as well as analyses based on different deformation mode sets, providing an in-depth insight on the member behavioural mechanics in both elastic and inelastic regimes.

Coworker feedback seeking and feedback environment in China: An expectation states theory approach

2019 ◽  
Vol 47 (9) ◽  
pp. 1-10 ◽  
Author(s):  
Zhenxing Gong ◽  
Mengshuang Liu ◽  
Di Xin ◽  
Faheem Gul Gilal ◽  
Kui Yin ◽  
...  
Keyword(s):  
Design And Technology ◽  
Theory Approach ◽  
Feedback Seeking ◽  
Feedback Environment ◽  
Expectation States ◽  
Industrial Enterprises ◽  
Seeking Behavior ◽  
Expectation States Theory ◽  
The Impact ◽  
The Relationship

We empirically explored the impact of feedback seeking, including feedback inquiry and monitoring, on the coworker feedback environment via coworker identification. Participants were 264 employees who worked in research and development, design, and technology sectors of industrial enterprises in China. The results indicated that feedback monitoring, feedback inquiry, and coworker identification were all positively related to the coworker feedback environment after controlling for the effects of demographic variables. Further, coworker identification fully mediated the relationship between feedback inquiry/monitoring and the coworker feedback environment. Our findings expand understanding of the feedback loop by bridging the gap between coworker feedback seeking and the coworker feedback environment. We recommend that coworkers encourage employees' feedback-seeking behavior so that the workplace feedback environment motivates them to ask for the help they need to work independently.

scholarly journals Police Stop and Frisk and the Impact of Race: A Focal Concerns Theory Approach

2021 ◽  
Vol 10 (6) ◽  
pp. 230
Author(s):  
Anthony Vito ◽  
George Higgins ◽  
Gennaro Vito
Keyword(s):  
Racial Differences ◽  
Theory Approach ◽  
Stop And Frisk ◽  
Focal Concerns ◽  
Police Decision Making ◽  
Reasonable Suspicion ◽  
Quasi Experimental ◽  
Verbal Threat ◽  
The Impact ◽  
Focal Concerns Theory

The findings of this study outline the racial differences in stop and frisk decisions by Illinois officers in consent searches and those based upon reasonable suspicion within the context of the elements of focal concerns theory. The analysis for this study was performed using propensity score matching (PSM) and allowed the researchers to create a quasi-experimental design to examine the race of the citizen and police decision making. According to our analysis of official Illinois law enforcement data, Black citizens, particularly males, were less likely to give their consent to a stop and frisk search. Black male citizens were also more likely to be stopped and searched due to an assessment of reasonable suspicion by the officer. Elements of focal concerns theory were also factors in pedestrian stops under conditions of consent and reasonable suspicion. Citizens judged as blameworthy were more likely to be stopped and frisked under conditions of consent and reasonable suspicion. The effect of a verbal threat and the officer’s prior knowledge about the citizen had even more significant impacts.

scholarly journals The Impact of Narrative Feedback, E-Learning Modules and Realistic Video and the Reduction of Misconception

2021 ◽  
Vol 11 (4) ◽  
pp. 158
Author(s):  
Abdul Halim ◽  
Elmi Mahzum ◽  
Muhammad Yacob ◽  
Irwandi Irwandi ◽  
Lilia Halim
Keyword(s):  
Biology Education ◽  
Free Fall ◽  
Percentage Reduction ◽  
Significant Treatment ◽  
Learning Modules ◽  
Physics Courses ◽  
Learning Platform ◽  
Quasi Experimental ◽  
E Learning ◽  
The Impact

Physics learning in universities utilized the Moodle-based e-learning media as an online learning platform. However, the effectiveness of remediating misconception using online media has not been widely researched. Therefore, this study was set to determine the level of misconception percentage reduction through the use of narrative feedback, the e-learning modules, and realistic video. The study was a quantitative approach with a quasi-experimental method involving 281 students who were taking basic physics courses in the Department of Physics, Chemistry, and Biology Education. The data collection used a three-tier diagnostic test based on e-learning at the beginning of the activity and after the treatment (posttest). The results of the data analysis with descriptive statistics show that the most significant treatment in reducing misconception percentage on the topic of free-fall motion was in the following order: narrative feedback, e-learning modules and realistic video. The misconception percentage reduction in the sub-concept of accelerated free- fall was effective for all types of the treatments.

scholarly journals Non-Parametric Generalized Additive Models as a Tool for Evaluating Policy Interventions

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 299
Author(s):  
Jaime Pinilla ◽  
Miguel Negrín
Keyword(s):  
Linear Regression ◽  
Regression Models ◽  
Linear Trend ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Linear Regression Models ◽  
Non Linear ◽  
Nonlinear Trends ◽  
The Impact ◽  
Non Parametric

The interrupted time series analysis is a quasi-experimental design used to evaluate the effectiveness of an intervention. Segmented linear regression models have been the most used models to carry out this analysis. However, they assume a linear trend that may not be appropriate in many situations. In this paper, we show how generalized additive models (GAMs), a non-parametric regression-based method, can be useful to accommodate nonlinear trends. An analysis with simulated data is carried out to assess the performance of both models. Data were simulated from linear and non-linear (quadratic and cubic) functions. The results of this analysis show how GAMs improve on segmented linear regression models when the trend is non-linear, but they also show a good performance when the trend is linear. A real-life application where the impact of the 2012 Spanish cost-sharing reforms on pharmaceutical prescription is also analyzed. Seasonality and an indicator variable for the stockpiling effect are included as explanatory variables. The segmented linear regression model shows good fit of the data. However, the GAM concludes that the hypothesis of linear trend is rejected. The estimated level shift is similar for both models but the cumulative absolute effect on the number of prescriptions is lower in GAM.

scholarly journals Does agricultural intensification cause tipping points in ecosystem services?

2021 ◽  
Author(s):  
Stephen C. L. Watson ◽  
Adrian C. Newton ◽  
Lucy E. Ridding ◽  
Paul M. Evans ◽  
Steven Brand ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Agricultural Intensification ◽  
Spatial Dynamics ◽  
Policy Option ◽  
List Type ◽  
Tipping Points ◽  
Software Models ◽  
Non Linear ◽  
Study Interval ◽  
The Impact

Abstract Context Agricultural intensification is being widely pursued as a policy option to improve food security and human development. Yet, there is a need to understand the impact of agricultural intensification on the provision of multiple ecosystem services, and to evaluate the possible occurrence of tipping points. Objectives To quantify and assess the long-term spatial dynamics of ecosystem service (ES) provision in a landscape undergoing agricultural intensification at four time points 1930, 1950, 1980 and 2015. Determine if thresholds or tipping points in ES provision may have occurred and if there are any detectable impacts on economic development and employment. Methods We used the InVEST suite of software models together with a time series of historical land cover maps and an Input–Output model to evaluate these dynamics over an 85-year period in the county of Dorset, southern England. Results Results indicated that trends in ES were often non-linear, highlighting the potential for abrupt changes in ES provision to occur in response to slight changes in underlying drivers. Despite the fluctuations in provision of different ES, overall economic activity increased almost linearly during the study interval, in line with the increase in agricultural productivity. Conclusions Such non-linear thresholds in ES will need to be avoided in the future by approaches aiming to deliver sustainable agricultural intensification. A number of positive feedback mechanisms are identified that suggest these thresholds could be considered as tipping points. However, further research into these feedbacks is required to fully determine the occurrence of tipping points in agricultural systems.

The impact of total sleep deprivation upon supine and head up tilt hemodynamics using non-linear analysis in firefighters

2021 ◽  
Vol 70 ◽  
pp. 102989
Author(s):  
Sławomir Kujawski ◽  
Katarzyna Buszko ◽  
Agnieszka Cudnoch-Jędrzejewska ◽  
Joanna Słomko ◽  
Djordje G. Jakovljevic ◽  
...  
Keyword(s):  
Sleep Deprivation ◽  
Linear Analysis ◽  
Total Sleep Deprivation ◽  
Non Linear ◽  
Head Up Tilt ◽  
The Impact

Selection of models to describe the temperature-dependent development of Neoleucinodes elegantalis (Lepidoptera: Crambidae) and its application to predict the species voltinism under future climate conditions

2021 ◽  
pp. 1-9
Author(s):  
Hevellyn Talissa dos Santos ◽  
Cesar Augusto Marchioro
Keyword(s):  
Climate Change ◽  
Linear Model ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Temperature Dependent ◽  
Dependent Development ◽  
Degree Day ◽  
Non Linear ◽  
The Impact

Abstract The small tomato borer, Neoleucinodes elegantalis (Guenée, 1854) is a multivoltine pest of tomato and other cultivated solanaceous plants. The knowledge on how N. elegantalis respond to temperature may help in the development of pest management strategies, and in the understanding of the effects of climate change on its voltinism. In this context, this study aimed to select models to describe the temperature-dependent development rate of N. elegantalis and apply the best models to evaluate the impacts of climate change on pest voltinism. Voltinism was estimated with the best fit non-linear model and the degree-day approach using future climate change scenarios representing intermediary and high greenhouse gas emission rates. Two out of the six models assessed showed a good fit to the observed data and accurately estimated the thermal thresholds of N. elegantalis. The degree-day and the non-linear model estimated more generations in the warmer regions and fewer generations in the colder areas, but differences of up to 41% between models were recorded mainly in the warmer regions. In general, both models predicted an increase in the voltinism of N. elegantalis in most of the study area, and this increase was more pronounced in the scenarios with high emission of greenhouse gases. The mathematical model (74.8%) and the location (9.8%) were the factors that mostly contributed to the observed variation in pest voltinism. Our findings highlight the impact of climate change on the voltinism of N. elegantalis and indicate that an increase in its population growth is expected in most regions of the study area.

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