1,436 research outputs found
Delineating adaptive esports involvement from maladaptive gaming: a self-regulation perspective.
The last decade has witnessed the rise of electronic sports (esports), yet little is known about how involvement in intensive esports relates to self-regulatory processes, such as executive functioning (EF). In this paper, we review the evidence on EF in problematic and non-problematic video-game use. We also consider research on EF in traditional sports athletes, as well as in 'exercise addiction'. The focus of the review is on two core components of EF, namely response inhibition and cognitive flexibility. The available evidence suggests that EF is a reliable marker for indexing specific types of sport and video-gaming expertise, but does not appear to consistently delineate maladaptive from adaptive video-game involvement. Future research avenues on EF that characterize esport players are suggested to advance this area
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Photovoltaic module and array performance characterization methods for all system operating conditions
This paper provides new test methods and analytical procedures for characterizing the electrical performance of photovoltaic modules and arrays. The methods use outdoor measurements to provide performance parameters both at standard reporting conditions and for all operating conditions encountered by typical photovoltaic systems. Improvements over previously used test methods are identified, and examples of the successful application of the methodology are provided for crystalline- and amorphous-silicon modules and arrays. This work provides an improved understanding of module and array performance characteristics, and perhaps most importantly, a straight- forward yet rigorous model for predicting array performance at all operating conditions. For the first time, the influences of solar irradiance, operating temperature, solar spectrum, solar angle-of- incidence, and temperature coefficients are all addressed in a practical way that will benefit both designers and users of photovoltaics
Problematic online gaming and the COVID-19 pandemic.
Stay-at-home mandates and quarantines related to the coronavirus (COVID-19) pandemic have led to greatly increased participation in online gaming. Initiatives such as #PlayApartTogether that promote gaming for socializing and stress reduction may achieve positive outcomes. Although gaming can be a healthy coping strategy for the majority, it can also pose risks to some vulnerable individuals. Protracted periods of social isolation and technology-based activity pose the danger of solidifying unhealthy lifestyle patterns, leading to difficulties to readaptation when the COVID-19 crisis has passed. Balanced and effective approaches to gaming during the COVID-19 pandemic are needed to support physical and psychological wellbeing
An exploratory study of public opinions on the use of hydrogen energy in Wales
The introduction of hydrogen into the energy market is being pursued by governments around the world in an effort to abate climate change, provide security of supply and reduce air pollution. While technological aspects are well researched, the social aspects of the transition are not. The public's attitude and perception of hydrogen energy will be of great importance as we move closer to the implementation of the technologies. Using two focus groups this exploratory study aims to identify Welsh public opinions on the production and end use of hydrogen energy. Gender differences were apparent, as women were generally more accepting of hydrogen technology. The main concerns were safety (both of use and in production) and cost. Cost remained paramount, even in the light of environmental considerations. The groups' attitude to the development of hydrogen technology was supportive but with the caveat that price and safety should not be compromised
Potential runoff and erosion comparison of four center pivot sprinklers
The operational characteristics of center pivot sprinklers are well documented but few
studies have been conducted to evaluate the effects that operating characteristics of a particular
sprinkler have on infiltration, runoff, and erosion of specific soil types. The objective of this study was
to evaluate potential runoff and erosion from common commercial center pivot sprinklers on three
widely distributed, south central Idaho soils. A modified commercial irrigation boom system was
used to emulate center pivot irrigation on experimental runoff plots. Sprinklers used in the study
were: 1) Nelson R3000 with brown plate, 2) Nelson R3000 with red plate, 3) Nelson S3000 with
purple plate, and 4) Senninger I-Wob with standard 9-groove plate. There were significant
differences in measured runoff percentages and measured erosion rates between center pivot
sprinkler types for the soils tested and experimental conditions. The magnitude of the differences
among sprinklers was equal to or greater than the differences between the soils tested. The I-Wob
and S3000 sprinklers exhibited the greatest measured runoff percentages and measured erosion
rates and the R3000 sprinklers exhibited the least runoff and erosion for the three soils tested. In
general, sprinkler types that visually appear to more evenly distribute sprinkler droplets over the
wetted area with respect to time exhibited the greatest measured runoff and measured erosion rates.
The relative ranking of the sprinklers in terms of measured runoff percentages and measured erosion
rates was consistent when four and six irrigation events were used to apply 75 mm of water. The
relative differences in runoff between the sprinklers tested were not directly proportional to sprinkler
droplet kinetic energy per unit water volume applied. This outcome is in conflict with conventional
theory on soil surface sealing from droplet impact. Possible explanations include incorrect
representation of sprinkler droplet kinetic energy, conventional soil surface sealing theory does not
apply to the soils used in this study, or some unknown factor is dominating the infiltration and runoff
process for the study conditions
Characterizing droplet kinetic energy applied by moving spray-plate center pivot irrigation sprinklers
The kinetic energy of discrete drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. Under center pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy development can have a substantial effect on seasonal runoff and soil erosion. In the design of center pivot irrigation systems, selection of sprinklers with minimum applied kinetic energy could potentially minimize seasonal runoff and erosion hazard. Size and velocity of drops from five common center pivot sprinklers with flow rates of approximately 43 L/min were measured using a laser in the laboratory. The data were used to evaluate various approaches to characterize kinetic energy transferred to the soil by each of the five sprinklers on a center pivot irrigation system lateral with 2.5 m spacing between sprinklers. Specific power, which represents the rate kinetic energy per unit area is transferred to the soil as a function of distance from a sprinkler and analogous to a sprinkler radial water application rate distribution, was used to estimate actual kinetic energy transferred to the soil by overlapping specific power profiles of sprinklers equally spaced along a center pivot lateral. Kinetic energy of irrigation sprinklers has traditionally been characterized using area weighted kinetic energy per unit drop volume. This method of characterization heavily weights the largest drops which travel the farthest from the sprinkler and have the largest kinetic energy. This characterization was not correlated to actual kinetic energy transferred to the soil by the sprinklers. Sprinkler kinetic energy per unit volume of sprinkler discharge was also used to characterize sprinkler kinetic energy calculated but was not correlated to actual kinetic energy transferred to the soil by the sprinklers. However, kinetic energy per unit volume of sprinkler discharge was found to be more representative than kinetic energy per unit drop volume. Measured runoff and sediment yield of the sprinklers from a previous study were compared to time averaged specific power. Runoff and erosion appeared to be more dependent upon sprinkler type than time averaged specific power. The sprinklers with the lowest runoff and sediment yield had the lowest time averaged specific power. However, there was a substantial increase in runoff and sediment yield with little associated increase in time averaged specific power applied for some sprinklers. Visually, the functional difference between sprinklers was the manner in which water drops were distributed over the wetted area with respect to time. Sprinklers that visually appeared to distribute water drops more evenly over the wetted area with respect to time had the highest runoff and sediment yield, and sprinklers that had well defined rotating streams of water drops had the lowest runoff and sediment yield, largely independent of time-averaged specific power applied to the soil
Determination of kinetic energy applied by center pivot sprinklers
The kinetic energy of discrete drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. Under center pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy development can have a substantial effect on seasonal runoff and soil erosion. In the design of center pivot irrigation systems, selection of sprinklers with minimum applied kinetic energy could potentially minimize seasonal runoff and erosion hazard. Size and velocity of drops from five common center pivot sprinklers were measured using a laser in the laboratory. The data were used to calculate kinetic energy transferred to the soil by each sprinkler on a center pivot irrigation system lateral with 2.5 m spacing between sprinklers. Specific power, which represents the rate that kinetic energy is transferred to the soil as a function of distance from a sprinkler and analogous to a sprinkler radial water application rate distribution, was used to estimate actual kinetic energy transferred to the soil by overlapping specific power profiles of sprinklers equally spaced along a center pivot lateral. Kinetic energy of irrigation sprinklers has traditionally been characterized using area weighted kinetic energy per unit drop volume. This characterization was found not to be correlated to actual kinetic energy transferred to the soil by the sprinklers. The results demonstrated that sprinklers with the smallest drop sizes do not necessarily transfer the least kinetic energy per unit depth of water applied. Conversely, sprinklers with the largest drop sizes do not necessarily transfer the greatest kinetic energy to the soil
Use of self-organizing maps to estimate furrow sediment loss in western U.S.
The area irrigated by furrow irrigation in the U.S. has been steadily decreasing but still represents about 20% of the total irrigated area in the U.S. Furrow irrigation sediment loss is a major water quality issue in the western U.S. and a method for estimating sediment loss is needed to quantify the environmental impacts and estimate effectiveness and economic value of conservation practices. The objective of the study was to investigate the use of the unsupervised machine learning technique Kohonen self-organizing maps (KSOM) to predict furrow sediment loss. Historical published and unpublished data sets containing measurements of furrow irrigation sediment loss in the western U.S. were assembled into a furrow sediment loss data set comprising over 2000 furrows. Despite the immunity of KSOMs to parameter variability, the inherent variability in measured furrow sediment loss limited the ability of a KSOM model to reliability predict furrow sediment loss. Furrow sediment loss was under predicted by 44% on average with a linear regression coefficient of determination of 0.6. The KSOM model was placing little weight on measured sediment loss in the input data set, indicating that it was clustering the data based on input parameters defining hydraulic and soil conditions. This outcome was used to develop a transfer learning approach for predicting furrow sediment loss. The transfer learning approach used a KSOM to cluster data records of similar of hydraulic and soil conditions in the data set. Mean measured sediment loss and furrow flow rate of each cluster was determined based on data set vectors assigned to a cluster by the KSOM. Furrow sediment loss prediction was obtained by applying an input vector to the KSOM to identify the cluster the input vector most closely matches. Then the mean measured sediment loss of the identified cluster was adjusted for any difference between the input vector furrow flow rate and cluster mean furrow flow rate to obtain a prediction of furrow sediment loss. Predicted furrow sediment loss was 16% less than measured sediment loss on average with a coefficient of determination of 0.82. When the data set was randomly split into model development (90%) and validation (10%) data sets the prediction results were similar
Droplet Kinetic Energy from Center-Pivot Sprinklers
The kinetic energy of discrete water drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. Under center-pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop
canopy development can have a substantial effect on seasonal runoff and soil erosion. In the design of center-pivot irrigation systems, selection of sprinklers with minimum applied kinetic energy could potentially minimize the seasonal runoff and erosion hazard. The size and velocity of drops from common rotating spray-plate sprinklers center-pivot sprinklers with flow rates of
approximately 40 and 20 L/ min were measured using a laser in the laboratory. The data were used to evaluate two approaches to characterize the kinetic energy transferred to the soil by rotating spray-plate sprinklers on a center-pivot irrigation system lateral with 3 m spacing between sprinklers. Specific power represents the rate at which kinetic energy per unit area is transferred to the soil as a function of distance from a sprinkler and is analogous to a sprinkler radial water application rate distribution. Specific power was used to estimate actual kinetic energy transferred to the soil by overlapping specific power profiles of sprinklers equally spaced along a center-pivot lateral. Kinetic energy of irrigation sprinklers has traditionally been characterized using area-weighted kinetic energy per unit drop volume. This method heavily favors the largest drops, which travel the farthest from the sprinkler and have the largest kinetic energy and does not account for the volume of water applied by each drop size. Sprinkler kinetic energy per unit volume of sprinkler discharge was not well correlated to actual kinetic energy transferred to the soil by the sprinklers
Transient Soil Surface Sealing and Infiltration Model for Bare Soil Under Droplet Impact.
The marked reduction in infiltration rate caused by formation of a soil surface seal due to water droplet impact on bare soil is a well known phenomenon but is rarely considered in infiltration models, especially under center pivot irrigation. Water application rates under center pivot irrigation commonly exceed infiltration rate, especially near the end of the system lateral. This can lead to off-site runoff and erosion, but more importantly results in field-scale non-uniform water infiltration that can substantially reduce water use efficiency of these irrigation systems. The objective of this study was to develop a sealing soil infiltration model that considers transient soil seal formation on a 30 min or less time scale and can potentially be applied to center pivot sprinkler irrigation systems. A sealing soil infiltration model was developed using an explicit finite difference solution scheme with a transient soil seal formation model, which is unique from other studies in that it explicitly uses droplet specific power as the driving factor for formation of a soil surface seal. The form of the transient seal formation model is also unique in that it is expressed as a rational function of specific power rather than an exponential decay function of droplet kinetic energy. The model was applied to published runoff data from two rainfall simulation studies with varying droplet kinetic energies and application rates on three soils. The sealing soil infiltration model represented measured infiltration rates very well for all rainfall simulator tests
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