Assessing Horizontal Force Production in Resisted Sprinting: Computation and Practical Interpretation

2019 ◽  
Vol 14 (5) ◽  
pp. 689-693 ◽  
Author(s):  
Matt R. Cross ◽  
Farhan Tinwala ◽  
Seth Lenetsky ◽  
Scott R. Brown ◽  
Matt Brughelli ◽  
...  
Keyword(s):  
Performance Enhancement ◽  
Force Production ◽  
Test Case ◽  
Horizontal Force ◽  
Sprint Training ◽  
Field Methods ◽  
Potential Methods ◽  
Training Apparatus ◽  
The Impact ◽  
Resisted Sprinting

The assessment of horizontal force during overground sprinting is increasingly prevalent in practice and research, stemming from advances in technology and access to simplified yet valid field methods. As researchers search out optimal means of targeting the development of horizontal force, there is considerable interest in the effectiveness of external resistance. Increasing attention in research provides more information surrounding the biomechanics of sprinting in general and insight into the potential methods of developing determinant capacities. However, there is a general lack of consensus on the assessment and computation of horizontal force under resistance, which has resulted in a confusing narrative surrounding the practical applicability of loading parameters for performance enhancement. As such, the aim of this commentary was twofold: to provide a clear narrative of the assessment and computation of horizontal force in resisted sprinting and to clarify and discuss the impact of methodological approaches to subsequent training implementation. Horizontal force computation during resisted sleds, a common sprint-training apparatus in the field, is used as a test case to illustrate the risks associated with substandard methodological practices and improperly accounting for the effects of friction. A practical and operational synthesis is provided to help guide researchers and practitioners in selecting appropriate resistance methods. Finally, an outline of future challenges is presented to aid the development of these approaches.

Very-Heavy Sled Training for Improving Horizontal-Force Output in Soccer Players

2017 ◽  
Vol 12 (6) ◽  
pp. 840-844 ◽  
Author(s):  
Jean-Benoît Morin ◽  
George Petrakos ◽  
Pedro Jiménez-Reyes ◽  
Scott R. Brown ◽  
Pierre Samozino ◽  
...  
Keyword(s):  
Body Mass ◽  
Effect Size ◽  
Reaction Force ◽  
Force Production ◽  
Sprint Performance ◽  
Soccer Players ◽  
Control Group ◽  
Horizontal Force ◽  
Sprint Training ◽  
Practical Applications

Background:Sprint running acceleration is a key feature of physical performance in team sports, and recent literature shows that the ability to generate large magnitudes of horizontal ground-reaction force and mechanical effectiveness of force application are paramount. The authors tested the hypothesis that very-heavy loaded sled sprint training would induce an improvement in horizontal-force production, via an increased effectiveness of application.Methods:Training-induced changes in sprint performance and mechanical outputs were computed using a field method based on velocity–time data, before and after an 8-wk protocol (16 sessions of 10- × 20-m sprints). Sixteen male amateur soccer players were assigned to either a very-heavy sled (80% body mass sled load) or a control group (unresisted sprints).Results:The main outcome of this pilot study is that very-heavy sled-resisted sprint training, using much greater loads than traditionally recommended, clearly increased maximal horizontal-force production compared with standard unloaded sprint training (effect size of 0.80 vs 0.20 for controls, unclear between-groups difference) and mechanical effectiveness (ie, more horizontally applied force; effect size of 0.95 vs –0.11, moderate between-groups difference). In addition, 5-m and 20-m sprint performance improvements were moderate and small for the very-heavy sled group and small and trivial for the control group, respectively.Practical Applications:This brief report highlights the usefulness of very-heavy sled (80% body mass) training, which may suggest value for practical improvement of mechanical effectiveness and maximal horizontal-force capabilities in soccer players and other team-sport athletes.Results:This study may encourage further research to confirm the usefulness of very-heavy sled in this context.

scholarly journals Photovoltaic Power Forecasting: Assessment of the Impact of Multiple Sources of Spatio-Temporal Data on Forecast Accuracy

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1432
Author(s):  
Xwégnon Ghislain Agoua ◽  
Robin Girard ◽  
Georges Kariniotakis
Keyword(s):  
Satellite Images ◽  
Forecast Accuracy ◽  
Absolute Error ◽  
Data Sources ◽  
Test Case ◽  
Temporal Data ◽  
Multiple Sources ◽  
Forecasting Error ◽  
Spatio Temporal ◽  
The Impact

The efficient integration of photovoltaic (PV) production in energy systems is conditioned by the capacity to anticipate its variability, that is, the capacity to provide accurate forecasts. From the classical forecasting methods in the state of the art dealing with a single power plant, the focus has moved in recent years to spatio-temporal approaches, where geographically dispersed data are used as input to improve forecasts of a site for the horizons up to 6 h ahead. These spatio-temporal approaches provide different performances according to the data sources available but the question of the impact of each source on the actual forecasting performance is still not evaluated. In this paper, we propose a flexible spatio-temporal model to generate PV production forecasts for horizons up to 6 h ahead and we use this model to evaluate the effect of different spatial and temporal data sources on the accuracy of the forecasts. The sources considered are measurements from neighboring PV plants, local meteorological stations, Numerical Weather Predictions, and satellite images. The evaluation of the performance is carried out using a real-world test case featuring a high number of 136 PV plants. The forecasting error has been evaluated for each data source using the Mean Absolute Error and Root Mean Square Error. The results show that neighboring PV plants help to achieve around 10% reduction in forecasting error for the first three hours, followed by satellite images which help to gain an additional 3% all over the horizons up to 6 h ahead. The NWP data show no improvement for horizons up to 6 h but is essential for greater horizons.

Mental Fatigue Reduces the Benefits of Self-Controlled Feedback on Learning a Force Production Task

2021 ◽  
pp. 003151252110373
Author(s):  
Milad Khojasteh Moghani ◽  
Rasool Zeidabadi ◽  
Mohammad Reza Shahabi Kaseb ◽  
Iman Bahreini Borujeni
Keyword(s):  
Repeated Measures ◽  
Transfer Test ◽  
Force Production ◽  
Mental Fatigue ◽  
The Self ◽  
Acquisition Phase ◽  
Production Task ◽  
Significant Group ◽  
The Impact ◽  
Force Production Task

This study investigated the impact of mental fatigue and self-controlled versus yoked feedback on learning a force production task. We randomly assigned 44 non-athlete male students (Mage = 21.4, SD = 1.4 years) to four groups; (a) MF&SCF = mental fatigue & self-controlled feedback, (b) MF&Y = mental fatigue & yoked, (c) NMF&SCF = no mental fatigue & self-controlled feedback, and (d) NMF&Y = no mental fatigue & yoked). SCF group participants were provided feedback whenever they requested it, while YK group participants received feedback according to a schedule created by their SCF counterparts. To induce mental fatigue, participants performed a Stroop color-word task for one hour. During the acquisition (practice) phase, participants were asked to produce a given percentage of their maximum force (20%) in 12 blocks of six trials. We recorded the participants’ absolute error at the end of the acquisition phase, the immediate retention test, the first transfer test, and the second transfer test (after 24 hours and without any further mental fatigue). The acquisition phase data were analyzed in a 2 (feedback) × 2 (mental fatigue) × 12 (block) ANOVA with repeated measures on the last factor, while the retention and transfer data were analyzed in 2 (feedback) × 2 (mental fatigue) ANOVAs. We found that all four groups made significant progress during practice ( p < .001), but there were no significant group differences during this phase ( p>.05). There was a significant interaction effect of self-controlled feedback and mental fatigue at retention ( p = .018) and transfer testing ( p < .001). In the mental fatigue condition, participants in the self-controlled group had poorer learning compared to participants in the yoked group; but when not mentally fatigued, participants in the self-controlled group had better learning than those in the yoked group. These findings suggest that mental fatigue reduces typical advantages of self-controlled feedback in motor learning.

scholarly journals Ability of near-infrared spectroscopy and chemometrics to predict the age of mosquitoes reared under different conditions

2020 ◽  
Author(s):  
Oselyne Ong ◽  
Elise Kho ◽  
Pedro Esperança ◽  
Chris Freebairn ◽  
Floyd Dowell ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Field Application ◽  
Machine Learning Techniques ◽  
Island Population ◽  
Natural Environments ◽  
Pls Regression ◽  
Field Methods ◽  
The Impact

Abstract Background: Practical, field-ready age-grading tools for mosquito vectors of disease are urgently needed because of the impact that daily survival has on vectorial capacity. Previous studies have shown that near-infrared spectroscopy (NIRS), in combination with chemometrics and predictive modeling, can forecast the age of laboratory-reared mosquitoes with moderate to high accuracy. It remains unclear whether the technique has utility for identifying shifts in the age structure of wild-caught mosquitoes. Here we investigate whether models derived from the laboratory strain of mosquitoes can be used to predict the age of mosquitoes grown from pupae collected in the field. Methods: NIR spectra from adult female Aedes albopictus mosquitoes reared in the laboratory (2, 5, 8, 12 and 15 days old) were compared to spectra from mosquitoes emerging from wild-caught pupae (1, 7 and 14 days old). Different partial least squares (PLS) regression methods trained on spectra from laboratory mosquitoes were evaluated on their ability to predict the age of mosquitoes from more natural environments. Results: Models trained on spectra from laboratory-reared material were able to predict the age of other laboratory-reared mosquitoes with moderate accuracy and successfully differentiated all day 2 and 15 mosquitoes. Models derived with laboratory mosquitoes could not differentiate between field-derived age groups, with age predictions relatively indistinguishable for day 1-14. Pre-processing of spectral data and improving the PLS regression framework to avoid overfitting can increase accuracy, but predictions of mosquitoes reared in different environments remained poor. Principle component analysis confirms substantial spectral variations between laboratory and field-derived mosquitoes despite both originating from the same island population. Conclusions: Models trained on laboratory mosquitoes were able to predict ages of laboratory mosquitoes with good sensitivity and specificity though they were unable to predict age of field-derived mosquitoes. This study suggests that laboratory-reared mosquitoes do not capture enough environmental variation to accurately predict the age of the same species reared under different conditions. Further research is needed to explore alternative pre-processing methods and machine learning techniques, and to understand factors that affect absorbance in mosquitoes before field application using NIRS.

scholarly journals A copula-based assessment of Bartlett–Lewis type of rainfall models for preserving drought statistics

2013 ◽  
Vol 10 (6) ◽  
pp. 7469-7516 ◽  
Author(s):  
M. T. Pham ◽  
W. J. Vanhaute ◽  
S. Vandenberghe ◽  
B. De Baets ◽  
N. E. C. Verhoest
Keyword(s):  
Time Series ◽  
Important Variable ◽  
Drought Severity ◽  
Test Case ◽  
Rainfall Time Series ◽  
Climate Data ◽  
Drought Duration ◽  
Environmental Consequences ◽  
Stochastic Point Process ◽  
The Impact

Abstract. Of all natural disasters, the economic and environmental consequences of droughts are among the highest because of their longevity and widespread spatial extent. Because of their extreme behaviour, studying droughts generally requires long time series of historical climate data. Rainfall is a very important variable for calculating drought statistics, for quantifying historical droughts or for assessing the impact on other hydrological (e.g. water stage in rivers) or agricultural (e.g. irrigation requirements) variables. Unfortunately, time series of historical observations are often too short for such assessments. To circumvent this, one may rely on the synthetic rainfall time series from stochastic point process rainfall models, such as Bartlett–Lewis models. The present study investigates whether drought statistics are preserved when simulating rainfall with Bartlett–Lewis models. Therefore, a 105 yr 10 min rainfall time series obtained at Uccle, Belgium is used as test case. First, drought events were identified on the basis of the Effective Drought Index (EDI), and each event was characterized by two variables, i.e. drought duration (D) and drought severity (S). As both parameters are interdependent, a multivariate distribution function, which makes use of a copula, was fitted. Based on the copula, four types of drought return periods are calculated for observed as well as simulated droughts and are used to evaluate the ability of the rainfall models to simulate drought events with the appropriate characteristics. Overall, all Bartlett–Lewis type of models studied fail in preserving extreme drought statistics, which is attributed to the model structure and to the model stationarity caused by maintaining the same parameter set during the whole simulation period.

scholarly journals Well Water Site Selection at Local Scale Using Geographical Information System for Flood Victim in Malaysia

2018 ◽  
Vol 50 (2) ◽  
pp. 205
Author(s):  
Koh Liew See ◽  
Nayan Nasir ◽  
Saleh Yazid ◽  
Hashim Mohmadisa ◽  
Mahat Hanifah ◽  
...  
Keyword(s):  
Water Supply ◽  
Spatial Data ◽  
Water Sources ◽  
Geographical Information ◽  
Well Water ◽  
Clean Water ◽  
Flood Events ◽  
Field Methods ◽  
The Impact ◽  
Area Data

Clean water supply is a major problem among flood victims during flood events. This article aims to determine the sites of well water sources that can be utilised during floods in the District of Kuala Krai, Kelantan. Field methods and Geographic Information Systems (GIS) were applied in the process of selecting flood victim evacuation centres and wells. The data used were spatial data obtained primarily, namely the well data, evacuation centre data and flood area data. The well and evacuation centre data were obtained by field methods conducted to determine the position of wells using global positioning system tools, and the same for the location of the evacuation centres. Information related to evacuation centres was obtained secondarily from multiple agencies and gathered into GIS as an evacuation centre attribute. The flood area data was also obtained via secondary data and was digitised using the ArcGIS software. The data processing was divided into two stages, namely the first stage of determining the flood victim evacuation centres to be used in this research in a structural manner based on two main criteria which were the extent to which an evacuation centre was affected by the flood and the highest capacity of victims for each district with the greatest impact to the flood affected population. The second stage was to determine the location of wells based on three criteria, namely i) not affected by flood, ii) the closest distance to the selected flood victim evacuation centre and iii) located at different locations. Among the main GIS analyses used were locational analysis, overlay analysis, and proximity analysis. The results showed that four (4) flood evacuation centres had been chosen and matched the criteria set, namely SMK Sultan Yahya Petra 2, SMK Manek Urai Lama, SMK Laloh and SK Kuala Gris. While six (6) wells had been selected as water sources that could be consumed by the flood victims at 4 evacuation centres in helping to provide clean water supply, namely Kg. Keroh 16 (T1), Kg. Batu Mengkebang 10 (T2), Lepan Meranti (T3), Kg. Budi (T4), Kg. Jelawang Tengah 2 (T5) and Kg. Durian Hijau 1 (T6). With the presence of the well water sources that can be used during flood events, clean water supply can be distributed to flood victims at the evacuation centres. Indirectly, this research can reduce the impact of floods in the future, especially in terms of clean water supply even during the hit of a major flood.

Study on the Lateral Deformation of the Flexible Berthing Pile of High-Pile Wharf under Ship Impact Load

2015 ◽  
Vol 744-746 ◽  
pp. 1184-1187
Author(s):  
Qiu Zhai ◽  
Wen Xiang ◽  
Yu Li
Keyword(s):  
Iterative Method ◽  
Analytical Method ◽  
Impact Load ◽  
Correlation Coefficients ◽  
Structure Design ◽  
Horizontal Force ◽  
Lateral Deformation ◽  
Mathematical Formula ◽  
The Impact

Flexible berthing pile-high pile wharf is a system which is composed of flexible berthing pile, rubber fender and pile platform. The system was divided into two forms based on the pile platform sustained the impact load or not. The method to analysis the lateral deformation of the pile was relatively mature when the platform was subjected to the impact load. Instead, when the pile platform is subjected to the impact load, the analytical method is unsatisfactory because of the complexity about the lateral deformation of the system. This paper takes the second condition as the research object, and study the lateral deformation of the pile, rubber fender and the pile platform. The mathematical formula is built on the horizontal force balancing condition and displacement coordination at the top of pile, the method to evaluate the correlation coefficients of the formulas is suggested, and the steps that solve the formulas by iterative method are described. The theory is clear, and the result can offer a reference for structure design and code revision.

Modeling Partial Admission in Control Stages of Small Steam Turbines With CFD

2018 ◽  
Author(s):  
Juri Bellucci ◽  
Filippo Rubechini ◽  
Andrea Arnone
Keyword(s):  
Steam Turbine ◽  
Three Dimensional ◽  
Admission Rate ◽  
Point Of View ◽  
Test Case ◽  
Steam Turbines ◽  
Turbine Stage ◽  
Performance Curves ◽  
Partial Admission ◽  
The Impact

This work aims at investigating the impact of partial admission on a steam turbine stage, focusing on the aerodynamic performance and the mechanical behavior. The partialized stage of a small steam turbine was chosen as test case. A block of nozzles was glued in a single “thick nozzle” in order to mimic the effect of a partial admission arc. Numerical analyses in full and in partial admission cases were carried out by means of three-dimensional, viscous, unsteady simulations. Several cases were tested by varying the admission rate, that is the length of the partial arc, and the number of active sectors of the wheel. The goal was to study the effect of partial admission conditions on the stage operation, and, in particular on the shape of stage performance curves as well as on the forces acting on bucket row. First of all, a comparison between the flow field of the full and the partial admission case is presented, in order to point out the main aspects related to the presence of a partial arc. Then, from an aerodynamic point of view, a detailed discussion of the modifications of unsteady rows interaction (potential, shock/wake), and how these ones propagate downstream, is provided. The attention is focused on the phenomena experienced in the filling/emptying region, which represent an important source of aerodynamic losses. The results try to deepen the understanding in the loss mechanisms involved in this type of stage. Finally, some mechanical aspects are addressed, and the effects on bucket loading and on aeromechanical forcing are investigated.

Nature 4.0: Assisted Evolution, De-extinction, and Ecological Restoration Technologies

2020 ◽  
Vol 20 (3) ◽  
pp. 9-27
Author(s):  
Leslie Paul Thiele
Keyword(s):  
Synthetic Biology ◽  
Ecological Restoration ◽  
Unintended Consequences ◽  
Test Case ◽  
Economic Interests ◽  
Human Needs ◽  
Basic Human Needs ◽  
The Impact ◽  
Benefits And Costs ◽  
Conservation Of Biodiversity

Humans have served their needs and interests by modifying plants, animals, and ecosystems for millennia. Technology has expanded, accelerated, and intensified the impact. Experimental efforts are now under way to rescue or re-create nature employing highly sophisticated technologies. These endeavors are not aimed at satisfying basic human needs or serving economic interests; their goal is the conservation of biodiversity and ecological restoration. At the same time, they fundamentally alter the fabric of life and guarantee unintended consequences. An examination of the ecological and cultural risks, benefits, and costs of employing synthetic biology to assist evolution and de-extinct species provides a valuable test case for environmentalists and conservationists grappling with the implications of ecological restoration technologies.

‘How I Managed’

2020 ◽  
pp. 107-155
Author(s):  
Tamara S. Wagner
Keyword(s):  
Nineteenth Century ◽  
Expert Knowledge ◽  
Historical Context ◽  
Popular Fiction ◽  
Infant Care ◽  
Narrative Form ◽  
Test Case ◽  
Advice Literature ◽  
Authorial Persona ◽  
The Impact

The second chapter explores how nineteenth-century parenting publications shaped popular narratives of babyhood and baby care. A critical analysis of the power of the print media in producing as well as spreading rapidly commodified advice material allows us to reconsider the still persistent phenomenon of competing books on babies in its historical context. The expanding market of expert instructions reconfigured images of babyhood, codifying the baby as a source of anxiety that required clinical knowledge and intervention. Women writers of popular childrearing manuals such as Eliza Warren, the main rival of the bestselling Isabella Beeton, packaged infant care advice in narratives, at once trading on and endeavouring to reshape this market. A crucial link between putatively professional, systematically presented, parenting instructions and the interpolation of infant care advice in popular fiction, Warren’s full-scale childrearing manual in narrative form, How I Managed My Children from Infancy to Marriage (1865), provides a test case of the shifting focus on personal experience and new expert knowledge in the selling of parenting publications. Since the nineteenth-century market for these publications was informed by a general move to hands-on, practical advice, Warren’s strategies in creating her authorial persona to market a mother’s experience formed a symptomatic and influential component in the impact of advice literature both on perceptions of baby care and on the literary baby.

Sign in / Sign up

Export Citation Format

Share Document