scholarly journals A ‘Speed—Difficulty—Accuracy’ Model Following a General Trajectory Motor Task with Spatial Constraints: An Information-Based Model

2020 ◽  
Vol 10 (21) ◽  
pp. 7516
Author(s):  
Salvatore Digiesi ◽  
Andrea Lucchese ◽  
Carlotta Mummolo
Keyword(s):  
Field Experiments ◽  
Experimental Studies ◽  
Motor Task ◽  
Research Field ◽  
Future Research ◽  
Motor Tasks ◽  
Task Execution ◽  
General Validity ◽  
Practical Applications ◽  
Speed Accuracy

Accuracy in executing a motor task, i.e., in following a given trajectory under geometrical constraints, is of great interest in work operations as well as in biomechanics applications. In the framework of the Fitts’ law research on motor tasks, experimental studies usually refer to simple trajectories which are of low interest in practical applications. Furthermore, available models lack predicting accuracy in executing motor tasks since do not systematically investigate effects of both speed and task difficulty (index of difficulty (ID)). In this paper, the authors propose a ‘Speed-ID-Accuracy’ model aiming at overcoming abovementioned limits. The model is of general validity as is based on an information-based formulation of a trajectory ID; the model proposed put into relation accuracy in task execution with a general trajectory and with the speed of task execution. Modeling accuracy, defined as standard deviation of the endpoint position, is carried out by regressing data available in the literature. The model proposed proves to be more accurate than the classical ‘Speed-Accuracy’ model in fitting available data. Such a result has been found in both numerical cases relating to ‘tunnel’ and ‘circular’ traveling tasks. Limits of data from field experiments are stressed out and future research field of investigations in work environment and biomechanics are figured out.

A review on recent advances and challenges of ionic wind produced by corona discharges with practical applications

2021 ◽  
Author(s):  
Jingguo Qu ◽  
Minjun Zeng ◽  
Dewei Zhang ◽  
Dakai Yang ◽  
Xiongwei Wu ◽  
...  
Keyword(s):  
Corona Discharge ◽  
Experimental Studies ◽  
Wind Generation ◽  
Future Research ◽  
Discharge Process ◽  
Ionic Wind ◽  
Practical Applications ◽  
Wind Generators ◽  
Wide Range ◽  
Gas Ionization

Abstract Ionic wind, an induced phenomenon during corona discharge, possessing the features of silent operation and no moving parts, has a wide range of applications. Ionic wind generation is accompanied by complex physical processes, involving gas ionization, ion recombination, flow, and various chemical reactions, as well as mutual couplings between some of them. Therefore, understanding the corona discharge process and ionic wind generation is crucial for researchers and engineers to better utilize this phenomenon in practical applications. In this review, the principles of corona discharge and its induced ionic wind are presented. Subsequently, ionic wind generators (IWGs) are discussed according to their applications, and the corresponding advances based on experimental studies and numerical simulations are also reviewed. Moreover, the challenges of transitioning the ionic wind technology from laboratory studies to practical applications are discussed. These challenges include the excessively high onset voltage of the corona, ozone emission, and influence of environmental conditions. Furthermore, the mechanisms of these barriers and several effective approaches for mitigating them are provided. Finally, some future research prospects and the conclusions are presented.

scholarly journals SPEED-ACCURACY TRADEOFF OF INSTEP KICK IN YOUNG SOCCER PLAYERS

2019 ◽  
pp. 543
Author(s):  
Bojan Rakojević ◽  
Vladimir Mrdaković ◽  
Nemanja Pažin ◽  
Radun Vulović ◽  
Bojan Leontijević ◽  
...  
Keyword(s):  
Motor Task ◽  
Motor Tasks ◽  
Radial Error ◽  
Significant Difference ◽  
Complex Motor ◽  
Instep Kick ◽  
Secondary Hypothesis ◽  
Primary Hypothesis ◽  
Speed Accuracy ◽  
Speed And Accuracy

The speed-accuracy trade-off of fast movements acts inversely and as such is known as the Fitts's law. The aim of this study is to determine how instep kick (IK) speed grading instructions affect the instep kick speed and accuracy. The primary hypothesis assumes that a complex motor task such as IK has an inverse relation between speed and accuracy, and the secondary hypothesis assumes that the applied speed grading instructions are sensitive. The research involved 13 male players, the average age of 15 years (±1.6). The experimental protocol included the execution of IK at five different speeds, determined by verbal instructions to respondents. For assessment of kicking accuracy, we observed the following dependent variables: mean radial error (MRE), bivariate variable error (BVE), and centroid radial error (CRE). Comparative analysis has shown that higher accuracy (reduced MRE) and kicking consistency (reduced BVE) are achieved under lower kicking speeds, but these effects were not achieved in regard to CRE. Subsequent analyses have shown that MRE has a tendency towards a significant difference between the slowest and fastest kicks (p=0.068-0.075), while in the case of BVE it has been found that there are differences between the slowest and all other speed levels (p≤0.05). The main findings of this study have indicated a partial existence (two of three variables) of an inverse relationship between speed and accuracy in complex motor tasks such as IK (multi-joint and discrete motion).

scholarly journals Optical metasurfaces towards multifunctionality and tunability

Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Kang Du ◽  
Hamdi Barkaoui ◽  
Xudong Zhang ◽  
Limin Jin ◽  
Qinghai Song ◽  
...  
Keyword(s):  
Research Field ◽  
Design Methods ◽  
Research Progress ◽  
Future Research ◽  
Innovative Design ◽  
Practical Applications ◽  
Light Manipulation ◽  
Optical Effects ◽  
New Material ◽  
Future Research Directions

Abstract Optical metasurfaces is a rapidly developing research field driven by its exceptional applications for creating easy-to-integrate ultrathin planar optical devices. The tight confinement of the local electromagnetic fields in resonant photonic nanostructures can boost many optical effects and offer novel opportunities for the nanoscale control of light–matter interactions. However, once the structure-only metasurfaces are fabricated, their functions will be fixed, which limits it to make breakthroughs in practical applications. Recently, persistent efforts have led to functional multiplexing. Besides, dynamic light manipulation based on metasurfaces has been demonstrated, providing a footing ground for arbitrary light control in full space-time dimensions. Here, we review the latest research progress in multifunctional and tunable metasurfaces. Firstly, we introduce the evolution of metasurfaces and then present the concepts, the basic principles, and the design methods of multifunctional metasurface. Then with more details, we discuss how to realize metasurfaces with both multifunctionality and tunability. Finally, we also foresee various future research directions and applications of metasurfaces including innovative design methods, new material platforms, and tunable metasurfaces based metadevices.

scholarly journals Emotional eating in healthy individuals and patients with an eating disorder: evidence from psychometric, experimental and naturalistic studies

2020 ◽  
Vol 79 (3) ◽  
pp. 290-299 ◽  
Author(s):  
Julia Reichenberger ◽  
Rebekka Schnepper ◽  
Ann-Kathrin Arend ◽  
Jens Blechert
Keyword(s):  
Food Intake ◽  
Binge Eating ◽  
Emotional Eating ◽  
Daily Life ◽  
Negative Emotions ◽  
Experimental Studies ◽  
Eating Behaviour ◽  
Future Research ◽  
Healthy Individuals ◽  
General Validity

Emotional eating has traditionally been defined as (over)eating in response to negative emotions. Such overeating can impact general health because of excess energy intake and mental health, due to the risks of developing binge eating. Yet, there is still significant controversy on the validity of the emotional eating concept and several theories compete in explaining its mechanisms. The present paper examines the emotional eating construct by reviewing and integrating recent evidence from psychometric, experimental and naturalistic research. Several psychometric questionnaires are available and some suggest that emotions differ fundamentally in how they affect eating (i.e. overeating, undereating). However, the general validity of such questionnaires in predicting actual food intake in experimental studies is questioned and other eating styles such as restrained eating seem to be better predictors of increased food intake under negative emotions. Also, naturalistic studies, involving the repeated assessment of momentary emotions and eating behaviour in daily life, are split between studies supporting and studies contradicting emotional eating in healthy individuals. Individuals with clinical forms of overeating (i.e. binge eating) consistently show positive relationships between negative emotions and eating in daily life. We will conclude with a summary of the controversies around the emotional eating construct and provide recommendations for future research and treatment development.

scholarly journals Comparative Perspectives on Racial Discrimination in Hiring: The Rise of Field Experiments

2020 ◽  
Author(s):  
Lincoln Quillian ◽  
Arnfinn H. Midtbøen
Keyword(s):  
Racial Discrimination ◽  
Race And Ethnicity ◽  
Field Experiments ◽  
Minority Groups ◽  
Experimental Studies ◽  
Ethnic Discrimination ◽  
Comparative Perspective ◽  
Future Research ◽  
Institutional Rules ◽  
Hiring Discrimination

This article reviews studies of discrimination against racial and ethnic minority groups in hiring in cross-national comparative perspective. We focus on field-experimental studies of hiring discrimination: studies that use fictitious applications from members of different racial and ethnic group to apply for actual jobs. There are more than 140 field experimental studies of hiring discrimination against ethno-racial minority groups in 30 countries. These studies show that racial and ethnic discrimination is a pervasive international phenomenon that has hardly declined over time, although levels vary significantly over countries. The comparative perspective from this body of research helps to move beyond micro-models of employer decision-making to better understand the roles of history, social context, institutional rules, and racist ideologies in producing discrimination. Some racial discrimination is driven by correlated conditions like religion, but the clues producing most discrimination on these bases are fundamentally racialized. Studies suggest that institutional rules regarding race and ethnicity in hiring can have an important influence on levels of discrimination. Suggestions for future research on discrimination are discussed.

scholarly journals Re-imagining the country-of-origin effect: a promulgation approach

2018 ◽  
Vol 27 (7) ◽  
pp. 884-896 ◽  
Author(s):  
Mikael Andéhn ◽  
Jean-Noel Patrick L’espoir Decosta
Keyword(s):  
Field Experiments ◽  
Country Of Origin ◽  
Past Research ◽  
Research Area ◽  
Research Field ◽  
Future Research ◽  
Content Type ◽  
Extant Literature ◽  
Methodological Problems ◽  
Origin Effect

Purpose The country-of-origin effect (COO) has, as a research domain, suffered from several theoretical and methodological problems and tendencies including an incomplete conceptualization of its constituent components. The purpose of this study is to first problematize the concept in extant literature and to consequently propose a reconceptualization of the concept. Design/methodology/approach As part of lateral promulgation, the authors use theoretical and methodological ideas from other disciplines such as psychology, ethnography and geography to problematize the present conceptualization of COO in extant literature to reveal research possibilities relevant to, but underrepresented or absent in, COO research. Findings This study identifies several central theoretical and methodological problems and reveals that (1) COO is not necessarily linear and alternative modes of engagement with consumption need to be considered; (2) many of these problems can be addressed by alternative methodologies; and (3) COO operates at the level of symbolic orders that require a further engagement with the role of place in human experience. Research/limitations/implications The findings suggest that in future research, field experiments be considered to resolve some of the methodological artefacts that have hampered past research; qualitative methods be applied to uncover unexpected uses of place association beyond being mere quality proxies; and alternative areas of relevance, such as macro-level trade and exports from emerging economies, be entertained. Originality Value The study’s approach to problematizing and refining extant knowledge enable it to promulgate new knowledge and research directions for a research area that has historically suffered from a tendency to be self-referential.

Thermal Buckling of Plates and Shells

1993 ◽  
Vol 46 (10) ◽  
pp. 485-506 ◽  
Author(s):  
Earl A. Thornton
Keyword(s):  
Experimental Studies ◽  
Composite Plates ◽  
Past Research ◽  
Thermal Buckling ◽  
Future Research ◽  
Shallow Shells ◽  
Conical Shells ◽  
Practical Applications ◽  
Plates And Shells ◽  
Curved Panels

This review discusses research on thermal buckling of plates and shells since the first work in the 1950s. Elastic thermal buckling of metallic as well as composite plates and shells is described. The role of material thermal properties on thickness and spatial temperature gradients is demonstrated first. Then thermal buckling and postbuckling research for plates, shallow shells and curved panels, cylindrical and conical shells is presented. Analytical, computational and experimental studies are described. Governing equations and formulas for critical buckling temperatures are presented for several practical applications. An assessment of past research is made, and future research needs are highlighted.

scholarly journals Comparative Perspectives on Racial Discrimination in Hiring: The Rise of Field Experiments

2021 ◽  
Vol 47 (1) ◽  
Author(s):  
Lincoln Quillian ◽  
Arnfinn H. Midtbøen
Keyword(s):  
Race And Ethnicity ◽  
Field Experiments ◽  
Minority Groups ◽  
Experimental Studies ◽  
Ethnic Discrimination ◽  
Future Research ◽  
Annual Review ◽  
Publication Date ◽  
Institutional Rules ◽  
Hiring Discrimination

This article reviews studies of discrimination against racial and ethnic minority groups in hiring in cross-national perspective. We focus on field-experimental studies of hiring discrimination: studies that use fictitious applications from members of different racial and ethnic groups to apply for actual jobs. There are more than 140 field experimental studies of hiring discrimination against ethno-racial minority groups in 30 countries. We outline seventeen empirical findings from this body of studies. We also discuss individual and contextual theories of hiring discrimination, the relative strengths and weaknesses of field experiments to assess discrimination, and the history of such field experiments. The comparative scope of this body of research helps to move beyond micromodels of employer decision-making to better understand the roles of history, social context, institutional rules, and racist ideologies in producing discrimination. These studies show that racial and ethnic discrimination is a pervasive international phenomenon that has hardly declined over time, although levels vary significantly over countries. Evidence indicates that institutional rules regarding race and ethnicity in hiring can have an important influence on levels of discrimination. Suggestions for future research on discrimination are discussed. Expected final online publication date for the Annual Review of Sociology, Volume 47 is July 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Particle motion with air resistance

2012 ◽  
Vol 8 (1) ◽  
pp. 1-15
Author(s):  
Gy. Sitkei
Keyword(s):  
Basic Equation ◽  
Initial Conditions ◽  
Equation Of Motion ◽  
Terminal Velocity ◽  
Dimensionless Form ◽  
Wood Industry ◽  
Acceptable Error ◽  
General Validity ◽  
Practical Applications ◽  
Air Resistance

Motion of particles with air resistance (e.g. horizontal and inclined throwing) plays an important role in many technological processes in agriculture, wood industry and several other fields. Although, the basic equation of motion of this problem is well known, however, the solutions for practical applications are not sufficient. In this article working diagrams were developed for quick estimation of the throwing distance and the terminal velocity. Approximate solution procedures are presented in closed form with acceptable error. The working diagrams provide with arbitrary initial conditions in dimensionless form of general validity.

RECLAMATION AND CULVERT CROSSINGS MADE OF CORRUGATED PIPES ON SPAWNING STREAMS

2020 ◽  
pp. 68-77
Author(s):  
O.N. CHERNYKH ◽  
◽  
A.V. RBURLACHENKO
Keyword(s):  
Single Point ◽  
Experimental Studies ◽  
Fish Passage ◽  
Future Research ◽  
Fish Stocks ◽  
Metal Structures ◽  
Natural Reproduction ◽  
Spiral Shape ◽  
Corrugated Metal ◽  
Spawning Streams

Recommendations are presented for solving issues that arise in the design and operation of tubular transport crossings of corrugated metal structures through spawning streams while ensuring the safety and natural reproduction of fish stocks. There are discussed the results of experimental studies of culverts made of metal corrugated pipes with a normal and spiral shape of corrugation the bottom of which is buried and filled with suitable granular material to the level of the natural channel of a small watercourse. It is established that when 10% of the area of the corrugated pipe is occupied by stone filling, its throughput is reduced by about 10-12%. Based on the review of the existing literature and the results of laboratory experiments, data is provided to estimate the values of the roughness coefficients of the composite cross-section of a single-point junction and directions for future research on culvert reclamation are outlined. Studying of the structure of the velocity distribution in culverts can lead to the improved conditions for fish passage without installing special structural elements in the transit path of the fish passage structure.

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