Proximal-to-Distal Sequencing and Coordination Variability in the Volleyball Spike of Elite Youth Players: Effects of Gender and Growth

2018 ◽  
Vol 6 (2) ◽  
pp. 250-266 ◽  
Author(s):  
Ben Serrien ◽  
Maggy Goossens ◽  
Jean-Pierre Baeyens
Keyword(s):  
Degrees Of Freedom ◽  
Body Height ◽  
Development Program ◽  
Wrist Flexion ◽  
Trunk Flexion ◽  
Self Organizing Maps ◽  
And Performance ◽  
Coordination Patterns ◽  
Motion Capturing ◽  
Motor Control Systems

The aim of this article was to examine changes in elite youth volleyball players’ performance, proximal-to-distal sequencing, and coordination variability of the spike motion between the start and after 1 year of a talent development program. Eight boys and eight girls in late puberty/early adolescence were measured with 3D motion capturing for 2 consecutive years. Performance and performance variability increased and decreased, respectively, but both changes were not significantly correlated with growth. Gender differences were identified for proximal-to-distal sequencing, but a very strong similarity between both years was observed for all seven degrees of freedom (pelvis and trunk rotation, trunk flexion, shoulder horizontal adduction, shoulder internal rotation, elbow extension, and wrist flexion). The fact that this sequence was kept stable, despite marked growth effects, likely indicates that this sequence is biomechanically efficient and the motor control systems try to preserve it. Coordination variability was analyzed by coordination profiling with self-organizing maps. The decrease in coordination variability correlated strongly and significantly with increase in body height. Participants with stronger growth rates were observed to show smaller decreases in coordination variability, which possibly represents a mechanism to explore various coordination patterns to adapt to the more rapidly changing organismic constraints.

scholarly journals A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

2021 ◽  
Vol 11 (13) ◽  
pp. 5865
Author(s):  
Muhammad Ahsan Gull ◽  
Mikkel Thoegersen ◽  
Stefan Hein Bengtson ◽  
Mostafa Mohammadi ◽  
Lotte N. S. Andreasen Struijk ◽  
...  
Keyword(s):  
Upper Limb ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Trajectory Tracking Control ◽  
Upper Limb Exoskeleton ◽  
And Performance ◽  
Physically Disabled People ◽  
Human Upper Limb

Wheelchair mounted upper limb exoskeletons offer an alternative way to support disabled individuals in their activities of daily living (ADL). Key challenges in exoskeleton technology include innovative mechanical design and implementation of a control method that can assure a safe and comfortable interaction between the human upper limb and exoskeleton. In this article, we present a mechanical design of a four degrees of freedom (DOF) wheelchair mounted upper limb exoskeleton. The design takes advantage of non-backdrivable mechanism that can hold the output position without energy consumption and provide assistance to the completely paralyzed users. Moreover, a PD-based trajectory tracking control is implemented to enhance the performance of human exoskeleton system for two different tasks. Preliminary results are provided to show the effectiveness and reliability of using the proposed design for physically disabled people.

scholarly journals Observer-based robust integral of the sign of the error control of class I of underactuated mechanical systems: Theory and real-time experiments

2021 ◽  
pp. 014233122110313
Author(s):  
Afef Hfaiedh ◽  
Ahmed Chemori ◽  
Afef Abdelkrim
Keyword(s):  
Real Time ◽  
Error Control ◽  
Degrees Of Freedom ◽  
Sliding Mode ◽  
Mechanical Systems ◽  
Class I ◽  
Control Input ◽  
Underactuated Mechanical Systems ◽  
Control Scheme ◽  
And Performance

In this paper, the control problem of a class I of underactuated mechanical systems (UMSs) is addressed. The considered class includes nonlinear UMSs with two degrees of freedom and one control input. Firstly, we propose the design of a robust integral of the sign of the error (RISE) control law, adequate for this special class. Based on a change of coordinates, the dynamics is transformed into a strict-feedback (SF) form. A Lyapunov-based technique is then employed to prove the asymptotic stability of the resulting closed-loop system. Numerical simulation results show the robustness and performance of the original RISE toward parametric uncertainties and disturbance rejection. A comparative study with a conventional sliding mode control reveals a significant robustness improvement with the proposed original RISE controller. However, in real-time experiments, the amplification of the measurement noise is a major problem. It has an impact on the behaviour of the motor and reduces the performance of the system. To deal with this issue, we propose to estimate the velocity using the robust Levant differentiator instead of the numerical derivative. Real-time experiments were performed on the testbed of the inertia wheel inverted pendulum to demonstrate the relevance of the proposed observer-based RISE control scheme. The obtained real-time experimental results and the obtained evaluation indices show clearly a better performance of the proposed observer-based RISE approach compared to the sliding mode and the original RISE controllers.

scholarly journals Soft Spherical Tensegrity Robot Design Using Rod-Centered Actuation and Control

2016 ◽  
Author(s):  
Lee-Huang Chen ◽  
Kyunam Kim ◽  
Ellande Tang ◽  
Kevin Li ◽  
Richard House ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
Space Exploration ◽  
Robot Design ◽  
The Novel ◽  
Flexible Design ◽  
Spherical Robot ◽  
Potential Benefits ◽  
And Performance ◽  
And Control

This paper presents the design, analysis and testing of a fully actuated modular spherical tensegrity robot for co-robotic and space exploration applications. Robots built from tensegrity structures (composed of pure tensile and compression elements) have many potential benefits including high robustness through redundancy, many degrees of freedom in movement and flexible design. However to fully take advantage of these properties a significant fraction of the tensile elements should be active, leading to a potential increase in complexity, messy cable and power routing systems and increased design difficulty. Here we describe an elegant solution to a fully actuated tensegrity robot: The TT-3 (version 3) tensegrity robot, developed at UC Berkeley, in collaboration with NASA Ames, is a lightweight, low cost, modular, and rapidly prototyped spherical tensegrity robot. This robot is based on a ball-shaped six-bar tensegrity structure and features a unique modular rod-centered distributed actuation and control architecture. This paper presents the novel mechanism design, architecture and simulations of TT-3, the first untethered, fully actuated cable-driven six-bar tensegrity spherical robot ever built and tested for mobility. Furthermore, this paper discusses the controls and preliminary testing performed to observe the system’s behavior and performance.

Management System Competency Model and Development Program

2018 ◽  
Author(s):  
Mark S. Jean ◽  
Lynn A. Sikorski ◽  
Laura P. Zaleschuk
Keyword(s):  
Performance Management ◽  
Management System ◽  
Development Program ◽  
Competency Model ◽  
Management Systems ◽  
Success Rates ◽  
Road Map ◽  
Person Perspective ◽  
And Performance ◽  
Measurement And Evaluation

The pipeline industry continues to look for ways to improve its compliance and performance. Management systems have increased prevalence in the pipeline industry, with recognition that carefully designed and well-implemented management systems are the fundamental method that should be used to keep people safe, protect the environment and align organizational activities. Experience has shown significantly better success rates with management system implementation, both in terms of the quality and speed, when the person responsible for the design, implementation and sustainment of the management system has an integrated set of technical and enabling competencies. However, there is currently no standardized competency model that can be used to support a Management Systems Professional’s specialized knowledge and skills. The paper outlines the competencies needed by individuals to be effective in the design, implementation, measurement and evaluation of management systems. Applying a ‘whole-person’ perspective, the model includes business, relational and technical competencies that contribute to performance excellence for management system practitioners, including outlining example behaviours at target level performance and proficiency, and supported by a defined body of knowledge. This paper describes the Management System Competency Model, including how it can be used to create a position-specific development program for application within various organizations. This research establishes a basis for the creation of a practical, systematic and easy to use development road map for individuals and organizations who use or leverage a management system.

Performance Oriented Design of Semiregular Anisotropic Porous Structures

2018 ◽  
Author(s):  
Chao Xu ◽  
Lili Pan ◽  
Ming Li ◽  
Shuming Gao
Keyword(s):  
3D Printing ◽  
Porous Materials ◽  
Design Problem ◽  
Degrees Of Freedom ◽  
Design Space ◽  
Manufacturing Technology ◽  
Porous Structures ◽  
Precise Control ◽  
And Performance

Porous materials / structures have wide applications in industry, since the sizes, shapes and positions of their pores can be adjusted on various demands. However, the precise control and performance oriented design of porous structures are still urgent and challenging, especially when the manufacturing technology is well developed due to 3D printing. In this study, the control and design of anisotropic porous structures are studied with more degrees of freedom than isotropic structures, and can achieve more complex mechanical goals. The proposed approach introduces Super Formula to represent the structural cells, maps the design problem to an optimal problem using PGD, and solves the optimal problem using MMA to obtain the structure with desired performance. The proposed approach is also tested on the performance of the expansion of design space, the capture of the physical orientation and so on.

scholarly journals Choice of Pole and Ski Lengths Among Elite Cross-Country Skiers: The Influence of Sex and Performance Level

2021 ◽  
Vol 3 ◽  
Author(s):  
Per-Øyvind Torvik ◽  
Roland van den Tillaar ◽  
Øyvind Sandbakk
Keyword(s):  
Body Height ◽  
Sprint Performance ◽  
Performance Level ◽  
Whole Body ◽  
Men And Women ◽  
Male And Female ◽  
Secondary Purpose ◽  
Double Poling ◽  
Cross Country ◽  
And Performance

Cross-country (XC) skiers employ whole-body exercise to generate speed through poles and skis. The choice of optimal pole and ski lengths are therefore of high importance. The aim of this study was to document pole and ski lengths among elite male and female cross-country skiers in the classical and skating styles and to investigate sex differences in body-height-normalized pole and ski lengths. Our secondary purpose was to correlate body-height-normalized pole and ski lengths with performance level within both sexes. In total, Norwegian men and women (n = 87 and 36, respectively), participating in the Norwegian XC championship 2020, were investigated. Most athletes used poles close to the length allowed by the International Ski Federation (FIS) in the classical style among both sexes, with men using slightly longer poles than women (p < 0.05). Body-height-normalized pole lengths in skating were similar in men and women (around 90% of body height). Women used relatively longer ski lengths than men in both styles (p < 0.05). Women showed moderate correlations (r = 0.43, p < 0.05) between body-height-normalized pole lengths and sprint performance. Male and female cross-country skiers use as long classical ski poles as possible within the current regulations, while they use skating poles similar to recommendations given by the industry. The fact that men use longer body-height-normalized poles than women, where there is a correlation between pole length and sprint performance, indicate that faster women are able to better utilize the potential of using longer poles when double-poling. However, while women use relatively longer skis than men, no correlation with performance occurred for any of the sexes.

scholarly journals Peningkatan Kompetensi Dan Kinerja Tenaga Pendidik Paud Melalui Komunikasi Efektif

Gunahumas ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 225-235
Author(s):  
Renni Kusnaeni
Keyword(s):  
Program Implementation ◽  
Program Planning ◽  
Development Program ◽  
Effective Communication ◽  
Competency Development ◽  
Government Program ◽  
Implementation Evaluation ◽  
Inhibiting Factors ◽  
Inhibiting Factor ◽  
And Performance

Abstrak Penelitian tentang “Peningkatan Kompetensi dan Kinerja Tenaga Pendidik PAUD melalui Komunikasi Efektif di Kota Bandung dilatarbelakangi oleh kenyataan menjamurnya lembaga PAUD yang didirikan oleh masyarakat dalam upaya menyukseskan program pemerintah yang disebut PAUDISASI. Oleh karena itu penelitian ini disusun untuk mengetahui gambaran tentang peningkatan kompetensi dan kinerja pendidik melalui komunikasi efektif di lembaga PAUD meliputi perencanaan, pelaksanaan, evaluasi serta faktor pendukung dan penghambatnya. Adapun metode yang digunakan adalah analisis deskriptif kualitatif. Hasil observasi, wawancara dan studi dokumentasi terhadap program pengembangan kompetensi dan kinerja tenaga pendidik di PAUD Al-Jannah dan Psy Center Kota Bandung menunjukkan: 1) Perencanaan program disusun dengan baik; 2) Pelaksanaan program dilakukan oleh semua stakeholder disertai sosialisasi, pengarahan, pencatatan dan pengawasan dari kepala lembaga; 3) Evaluasi program dilakukan oleh yayasan, kepala lembaga secara komunikatif 4) Faktor pendukung berupa tersedianya sarana berbasis IT serta buku-buku panduan kurikulum, adanya alokasi anggaran (walau relatif terbatas), serta mayoritas guru berkualifikasi pendidikan S1. Adapun faktor penghambatnya adalah masih adanya guru yang belum memahami pentingnya pengembangan kompetensi dan kinerja, serta belum terbiasanya guru menghadapi rambu-rambu regulasi yang dilakukan. Kata kunci: kompetensi, kinerja, tenaga pendidik PAUD, komunikasi efektif Abstract The research on "Improving Competency and Performance of PAUD Educators through Effective Communication in Bandung is motivated by the reality of the proliferation of PAUD institutions established by the community in an effort to succeed a government program called PAUDISASI. Therefore this research is structured to find a picture of increasing the competence and performance of educators through effective communication in PAUD institutions including planning, implementation, evaluation and supporting and inhibiting factors. The method used is descriptive qualitative analysis. The results of observations, interviews and documentation studies on the competency development program and the performance of educators in Al-Jannah PAUD and the Bandung City Psy Center show: 1) Program planning is well structured; 2) Program implementation is carried out by all stakeholders accompanied by socialization, direction, recording and supervision from the head of the institution; 3) Program evaluation is carried out by the foundation, the head of the institution communicatively 4) Supporting factors such as the availability of IT-based facilities and curriculum guide books, the existence of budget allocations (although relatively limited), and the majority of teachers qualified with S1 education. The inhibiting factor is that there are still teachers who do not understand the importance of d Keywords: competence, performance, PAUD educators, effective communication

Development of Perforating System for Unique HPHT Injection Application

2021 ◽  
Author(s):  
Brenden Grove ◽  
Joseph MacGillivray ◽  
Jason Cook ◽  
Chris Hoelscher
Keyword(s):  
System Development ◽  
Development Program ◽  
Integrated System ◽  
Operational Flexibility ◽  
Test Configuration ◽  
Performance Requirements ◽  
Field Environment ◽  
High Pressure High Temperature ◽  
Sand Control ◽  
And Performance

Abstract An operator was developing a High-Pressure High-Temperature (HPHT) field in the U.S. Gulf of Mexico (GOM). Completion design for the injector wells was cased-and-perforated, with no mechanical sand control. This led to the requirement for a tubing-conveyed perforating (TCP) system, featuring deep-penetrating (DP) charges which would meet specific performance requirements, in order to enable the wells to achieve injectivity targets. A perforating system was therefore developed and qualified to meet these requirements. This was an integrated system development, including both mechanical and explosive components, with simultaneous attention to performance, reliability, and quality assurance in the eventual field environment. The development program yielded a 4-3/4-inch carrier system, perforating charges, firing head, and gun hanger. All key components and systems were qualified in customer-witnessed testing, and demonstrated to meet or exceed operational function and performance requirements. The pressure and temperature rating of the newly-developed system is 30,000 psi at 425 °F. Explosive train function reliability was demonstrated at 380 °F for up to 28 days. The newly-developed perforating shaped charge was confirmed to exceed the stringent penetration depth and casing hole diameter performance requirements at downhole conditions. The firing head offers operational flexibility by being configurable for up to 15 pressure cycles prior to detonation, with an adjustable initiation threshold pressure to reduce risk to the completion string. The gun hanger was customized and demonstrated to exceed load requirements, and reliably set and release, in a test configuration featuring operator-provided field casing.

Modeling the Ecological Footprint of Nations via Evolutionary Computation and Machine Learning Models

2011 ◽  
pp. 18-37
Author(s):  
Mohamed M. Mostafa
Keyword(s):  
Linear Regression ◽  
Environmental Sustainability ◽  
Ecological Footprint ◽  
Performance Metrics ◽  
Gene Expression Programming ◽  
Simulation Method ◽  
Mcmc Methods ◽  
Self Organizing Maps ◽  
Complete Representation ◽  
And Performance

The per capita Ecological Footprint (EF) is one of the most-widely recognized measures of environmental sustainability. It seeks to quantify the Earth’s biological capacity required to support human activity. This study uses gene expression programming and Self-organizing Maps (SOM) to predict, classify and cluster the EF of 140 nations. A Bayesian approach was used to formally test the research hypotheses. By formulating the linear regression in a probabilistic framework, a Bayesian linear regression model is derived, and a specific simulation method, i.e., Markov Chain Monte Carlo (MCMC), is utilized to estimate the model parameters. Bayesian MCMC methods allow a richer and more complete representation of complex EF data. It also provides a computationally attractive and straightforward method to develop a full and complete description of the inherent uncertainty in parameters, quantiles and performance metrics.

Leader Launch

2020 ◽  
pp. 235-260
Author(s):  
Candice Freeman
Keyword(s):  
Leadership Development ◽  
Organizational Development ◽  
Development Program ◽  
Instructional Interventions ◽  
Three Phase ◽  
Emerging Leadership ◽  
Improvement Interventions ◽  
Leadership Development Program ◽  
And Performance

This case study examines how a rural healthcare system implemented LeaderLaunch, a leadership development program specifically supporting all front-line to director-level leaders employed within the organization's facilities. John DeJoria, the healthcare system's Director of Organizational Development, is a seasoned instructional designer and Certified Professional in Learning and Performance (CPLP) who was charged with the opportunity of determining the system's leadership development needs and responding with aligned performance improvement interventions, intended to build competency and capacity in current, new, and emerging leadership. This case explains how John and his team designed, conducted, and utilized a three phase needs assessment to select and design instructional and non-instructional interventions.

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