Effects of cricket ball colour and illuminance levels on catching behaviour in professional cricketers

In recent years there have been many alterations to equipment and technology in professional cricket, including the introduction of white balls during day-night matches. In the present study simulated slip-catching performance and movement initiation time were examined in professional cricketers when ball colour and illuminance levels differed. Five male professional cricketers (mean age: 27.3 +/- 1.4 years) volunteered to catch a total of 60 cricket balls, 20 (10 red and 10 white) under each of three illuminance levels (571, 1143 and 1714 lux). Balls were projected from a ball machine at 20 m s(-1) (45 mph) over a distance of 8.4 m, to the subject's dominant side. Catching performance was measured using an established catching scale. Movement initiation times for each hand were also calculated for each trial using a motion-analysis system. Data were submitted to separate two-way (ball colour [2] x illuminance level [3]) repeated measures analysis of variance. No significant effects were obtained for ball colour or illuminance levels for either catching performance or movement initiation time. Neither ball colour nor light level (within the range tested) affected slip-catching performance and movement initiation times in professional cricketers. Therefore it was concluded that the changes made to ball colour and light conditions in professional cricket were not detrimental to catching performance.     

Objective and subjective assessments of lighting in a hospital setting: implications for health,safety and performance

A field study was conducted to evaluate the illumination levels, to examine the effect of lighting conditions (including lighting characteristics and disturbances) on employee satisfaction, job performance, safety and health, and to compare the employees' perception of lighting level with actual illuminance levels in a hospital setting using both questionnaire and physical illuminance measurements. The illumination levels varied across different locations within the hospital and were lower than standards for 52.2% of the workplaces surveyed. Most respondents indicated that at least one of the four lighting characteristics (i.e. light level, type of light sources, light colour and use of daylight) was inappropriate, and that at least one of the three lighting disturbances (i.e. flickering lights, glare and unwanted shadows) was a major disturbance to them. The employees' perceptions of illuminance generally reflected the actual illuminance levels. The more appropriate maintenance or installation of lighting fixtures was rated as the most appropriate for improving lighting. The findings suggest that environmental ergonomics should be given a more prominent role in hospital building and workplace design to support safer healthcare facilities (for staff and potentially for patients).

Practitioner Summary: Good lighting is essential to improve employee performance, health and safety. The findings suggest that quantitative physical measurements should be supplemented by qualitative subjective assessments to provide a more holistic approach where specific details about the lighting condition in each working environment are incorporated from the workers' perspective.     

Assessment of visual fatigue under LED tunable white light with different blue components

Light‐emitting diode (LED) light source has high intensity emission of blue components absent in the daylight spectra and regulates human physiology and behavior. The aim of this study was to explore the effects of LED tunable white light with different blue‐component intensities on visual fatigue based on human eye photoreceptors. The short (S)‐cone and melanopsin illuminance were about 212% and 82% higher for blue‐enriched white light than blue‐less white light, respectively. The photopic illuminance was same for these two lights. The results revealed that blue‐enriched LED tunable white light with higher illuminance of S cones had a significant effect on visual fatigue. Participants experienced more eye discomfort under blue‐enriched white light accompanied with decreased vision function and changes in the autonomic nervous system. Visual acuity and tear film stability declined, and heart rhythm changed more significantly under blue‐enriched white light than blue‐less white light. While memory performance did not decline with more severe visual fatigue, improved memory performance under blue‐enriched white light may be due to enhanced alertness or arousal associated with high melanopsin illuminance. Our results suggest that blue‐enriched white light with higher illuminance of S cones and melanopsin has beneficial effects on cognitive performance, but it can induce relatively more visual fatigue.     

The effects of helmet design and bowling speed on indices of stress in cricket batting

Abstract

Elite cricketers believe that the use of helmets may help to reduce anxiety when facing fast bowling although they risk visual impairment in time-stressed circumstances. This study aimed to determine the effects of helmet design and bowling speed on heart rate (HR), anxiety arid batting performance.

Elite batsman (n=12) faced 20 deliveries from a bowling machine at slow (21 m s^?1) and fast (42ms^?1 ) speeds under three different headgear conditions— helmet with bars, visorless helmet and no-helmet. State measures of anxiety were taken before and after each batting condition by questionnaire. Heart rate (HR) was monitored throughout the test session. Batting performance was filmed and rated for quality by expert coaches on the basis of bat contact, foot movement, element of attack and timing.

Repeated measures analysis of variance revealed no significant differences in HR or performance between helmet conditions. Batting performance was significantly better against slow bowling than fast (p<0·01) and no significant differences were found for HR between the bowling speeds. No significant correlations were found between HR, performance and state anxiety scores but there was a significant negative relationship between perceived quality of performance and post-batting A-state (r= ?0·62; p<0·05) in the barred helmet condition only.

It is concluded that elite cricketers experienced little change in the level of performance-related anxiety when wearing helmets of varying designs, even when faced with bowling of considerable speed. There was no evidence of performance decrements when wearing helmets with bars and visors which suggests that the use of maximum protection against the possibility of facial damage does not seriously affect the batsman's ability to track and play the ball.     

双光源环境下非真实感绘制色调获取方法研究

非真实感绘制场景中客体明暗色调的合理性和协调性直接影响到最后生成画面的效果。对双光源环境下非真实感绘制场景中客体色调的获取方法进行研究,提出一种双光源下基于“小球法”的色调信息提取方法,该方法假设场景中的客体表面均匀覆盖了一层大小相同的小球,相邻的两个小球间保持近似相切状态,通过计算每一个小球在双光源状态下被其它小球遮档的程度来确定该小球中心位置的明暗信息,以及每一个小球在双光源环境下所在位置的近似镜面反射光亮度。在绘制阶段,可利用这些色调信息控制在相应位置绘制“笔触”的色调,从而保证所生成的非真实感画面场景整体色调的合理性。该方法可应用于双光源下各种非真实感绘制明暗信息的获取,并且具有结构简单、计算速度快和可方便实现对场景中局部信息的调整等特点。实验结果验证了提出的方法的有效性。     

The effect of skill level,external frame of reference and environmental changes on one-handed catching

Abstract

Two groups of subjects designated ‘good’ (n= 12) and ‘poor’ (n= 10) catchers on the basis of a task-specific criterion were required to catch, one-handed, balls projected from a ball-projection machine under eight different conditions. Four of these comprised the ‘environment illuminated’ conditions (full light; hand obscured by an opaque screen; a see-through screen and an external vertical reference frame in the field of view) and four others the ‘environment dark’ conditions (catching hand wearing a glove painted with luminescent paint and u. v. illuminated ball in an otherwise dark room; ball illuminated by u. v. light; luminescent hand and external luminescent vertical reference plus u. v. illuminated ball; u. v.-illuminated ball, plus luminescent vertical reference).

While clear and significant differences - as was to be expected from the selection criteria imposed - were shown between the groups of ‘good’ and ‘poor’ catchers for all three dependent variables-number of catches, spatial errors and temporal errors-it was demonstrated that, for both groups, degrading the environment, by reducing the information available, resulted in a significant performance decrement on the dependent variables ‘number of catches’ and ‘temporal errors’. ‘Poor’ catchers were also shown to make significantly more spatial errors than ‘good’ catchers. Whereas the latter finding confirms earlier findings reported in the literature, the significant effect on performance of degrading the environment -particularly with respect to temporal errors - is new. The finding is discussed in the framework of the use of ‘tau’ (time to contact) in making judgements about when to initiate the grasp response.     

The effect of LED lighting on color discrimination and preference of elderly people

The purpose of this study is to find out the effects of light‐emitting diode (LED) lighting on elderly people's color discrimination and preference, to improve the lighting environment for elderly people. In this study, experiments were conducted under LED lighting with two different spectra (with color‐correlated temperature [CCT] of 2800K and 6000K), and three different illuminance levels (30lx; 100lx; 1000lx). Six elderly observers (aged 55–65 years) participated in the experiments and were exposed to each lighting condition to finish one trial of a color discrimination test (Farnsworth–Munsell 100‐Hue Test) and a 7‐scale, 6‐item preference evaluation test. We conclude that elderly people perform better in color discrimination with higher CCT of LED light sources, which compensate for their decreased lens transmission at short wavelength. Their performance also increases with higher illuminance (30lx‐1000lx) of LED lighting. Meanwhile, they prefer higher illuminance, which makes them find the lighting environment more comfortable, brighter, and better for reading; but for CCT, although they feel a higher CCT is better for reading, they still have different tastes regarding CCT of light sources. © 2011 Wiley Periodicals, Inc.     

Selection of character/background colour combinations for onscreen searching tasks: An eye movement,subjective and performance approach

The aim of the study was to investigate the effect of various character and background colour combinations on cognitive performance during onscreen searching tasks and to identify the best combinations with a multimodal approach of physiological (eye movement recording), subjective and performance data collection. In the absence of proper character and background colour combination the optimum performance for a cognitive task is greatly affected which in turn affects the productivity of the individual worker or communications among the operators working under the same network through information sharing. This study was designed by selecting six colours, i.e., white, black, yellow, red, blue, and green and subsequently combining them to 16 character and background colour combinations for a searching task. Right and left headed arrows were used as the character for the searching maneuver. Forty-four (N = 44) volunteers participated in the experiments. Various eye movement variables, legibility rating scale, NASA-TLX questionnaire, searching time and percentage of error were recorded. Subjects performed better wherever a good contrast was there because of a high legibility. A poorly contrasted display affected the physiological variables as well as subjective responses to negative directions. Among the combinations of dark character/light background, blue and red character on white background is highly recommended; and while that for light character/dark background, white is found to be the best character on blue and green backgrounds.     

Neuro-controller for broadcast lighting light-emitting diode to express white light with high color rendering index

Technical characteristics analysis related to correlated color temperature (CCT), color rendering, and illuminance is required to use light-emitting diode (LED) as broadcast lighting. In general, to realize a white light source with a high color rendering index (CRI), we selected the appropriate emission intensity of RGBW LED through trial and error. However, the characteristics of the LED light source and environmental conditions make it difficult to perform the procedure several times. The objective of this study was to design a system that could control illuminance, CCT, and ∆uv while having high CRI, as an LED control method for broadcasting lighting. The controller implements using a feed-forward neural network with excellent nonlinear function approximation capability. We measure data directly from the red green blue white (RGBW) LED system for neural network training. We then select data with high CRI from the measured raw data and choose data for neural network learning by removing measurement noise using the quadratic polynomial interpolation method. The performance evaluation confirms that the proposed neural network controller shows excellent results as an RGBW LED controller for broadcast lighting in the Planckian locus and all regions of white light.     

Shortcomings and user requirements associated with cricket helmets currently in use: A study on features for safety and usability

Wearing helmets has reduced the risk of head and facial injury among cricketers. Yet, design gaps are present in the cricket helmets currently being used. The aim of this research was to identify the shortcomings and user requirements pertinent to safety and usability of cricket helmets. The objectives were to explore the design criteria and the drawbacks of state-of-the-art cricket helmets, to identify user requirements for design and to analyse them. To collect data, a three-faceted approach, i.e. a literature review (n = 58), a video-based accident analysis (n = 24) and a user study (n = 42), was used. A frequency analysis technique based on the constant comparative method was used to identify and prioritize the shortcomings and user requirements. Findings from the three approaches were then triangulated to confirm the shortcomings and user requirements. Results revealed that poor fit, inadequate impact attenuation capacity and thermal discomfort are the main categories of shortcomings in the cricket helmets. Research on multi-objective optimisation of features for better fit, impact attenuation and thermal comfort (FIT) is suggested as future work.     

Association between objective and subjective assessments of environmental ergonomic factors in manufacturing plants

The association between objective and subjective assessments of environmental ergonomic factors including noise, lighting and heat were conducted in a field study in three manufacturing plants. Data were collected from 130 workstations using questionnaire and physical measurements of the noise (noise dosimetry), lighting (task area illuminance) and heat (wet bulb globe temperature – WBGT) levels. The recommended noise, illuminance and WBGT levels were not met in about half of the workstations surveyed, which was in agreement with low satisfaction levels with the environmental factors in the workplace. A considerable effect of the environmental factors was found on perceived workers' job performance, safety and health. The results from contingency coefficient analysis indicated a relatively good agreement between the measured noise, illuminance and WBGT levels and the workers' perception of these factors. The results suggest that quantitative physical measurements should be supplemented by qualitative subjective assessments to provide more specific and additional details about the environmental conditions in each workplace and consequently to improve workers' satisfaction, job performance, safety and health.Relevance to industryThe findings highlight the importance of environmental ergonomics and have implications for improvements in the design of the workplace to enhance workers' satisfaction, job performance, safety and health on areas where the environmental factors are not favourable. A better understanding of the environmental conditions and their effects in each working environment has the potential for a notable impact on productivity and workers' quality of life.     

Optimal batting orders in one-day cricket

This paper concerns the search for optimal or nearly optimal batting orders in one-day cricket. A search is conducted over the space of permutations of batting orders where simulated annealing is used to explore the space. A non-standard aspect of the optimization is that the objective function (which is the mean number of runs per innings) is unavailable and is approximated via simulation. The simulation component generates runs ball by ball during an innings taking into account the state of the match and estimated characteristics of individual batsmen. The methods developed in the paper are applied to the national team of India based on their performance in one-day international cricket matches.     

Training in a Continuous Ball Throwing and Catching Task

Abstract

A continuous ball throwing and catching task in which the ball remained captive on the end of a chain was given to 84 male students between the ages of 18 and 38 years. Initial and final test trials were carried out without restriction on viewing the ball throughout its trajectory, whereas the interspersed training trials (except for a control group) wero carried out under restricted (spatial) viewing conditions. Results supported the contention that it is not necessary to ‘ keep one's eye on the ball’ in order to obtain performance seores as good as those obtained when the opportunity to watch the ball all the time is available. Suggestions are made with regard to ‘ guidance ’ as a training device.     

A preliminary study on learning effect in a contact positioning task in a virtual environment

How the human central nervous system adjusts sensorimotor coordination to haptic stimuli is a major topic in several fields including robotics. There are studies focusing on contact positioning tasks such as catching a ball or a volley in tennis, where position control of a human hand is required only at the moment of contact for successful completion of the tasks. A previous study dealt with a task of catching a ball in a virtual environment, and reported an interesting observation of the learning process in the relationship between operational performance and energy consumption of an operator; however, the operational condition given to the operators in the previous study seemed to be relatively simple. The interest in this paper is similar to that of the previous study; however, this paper considers application of a slightly more complex operational condition to a task of catching a ball. For corresponding to increase of difficulty in operation in the task, two movements of a paddle for catching a ball are given to operators, and difference between the movements is observed. Although the final goal of the study in this paper is similar to that in the previous study, this paper considers how learning effect can be observed in operational performance by comparing the performance of novice operators with that of experienced operators. The comparison shows differences in the performances between the operators from three analytic aspects. This paper also considers how many operations are required for novice operators to exhibit the learning effect in operational performance.     

Allocating Weighted Jobs in Parallel

The classic balls-into-bins game considers the experiment of placing m balls independently and uniformly at random (i.u.r.) in n bins. For m=n , it is well known that the maximum load, i.e., the number of balls in the fullest bin is Θ(log n/log log n) , with high probability. It is also known (see [S2]) that a maximum load of O( m / n ) can be obtained for all m≥ n if each ball is allocated in one (suitably chosen) of two (i.u.r.) bins. Stemann presents a distributed algorithm to find the ``suitable' bin for each ball. The algorithm uses r communication rounds to achieve a maximum load of , with high probability. Adler et al. [ACMR] show that Stemann's protocol is optimal up to a constant factor for constant r . In this paper we extend the above results in two directions: we generalize the lower bound to arbitrary r≤log log n . This implies that Stemann's protocol is optimal for all r . Our key result is a generalization of Stemann's upper bound to weighted balls: Let W ^A (resp. W ^M ) denote the average (resp. maximum) weight of the balls. Furthermore, let Δ=W ^A /W ^M . Then the optimal maximum load is Ω(m/n⋅ W ^A +W ^M ) . We present a protocol that achieves a maximum load of γ⋅( m / n ⋅ W ^A +W ^M ) using O( log log n / log (γ⋅(m/n⋅Δ+1)) ) communication rounds. For uniform weights this matches the results of Stemann. In particular, we achieve a load of O( m / n ⋅ W ^A +W ^M ) using log log n communication rounds, which is optimal up to a constant factor. An extension of our lower bound shows that our algorithm also reaches a load which is within a constant factor of the optimal load in the case of weighted balls. All the balls-into-bins games model load balancing problems: the balls are jobs, the bins are resources, the task is to allocate the jobs to the resources in such a way that the maximum load is minimized. Our extension to weighted balls allows us to extend previous bounds to models where resource requirements may vary. For example, if the jobs are computing tasks, their running times may vary. Applications of such load balancing problems occur, e.g., for client-server networks and for multimedia-servers using disk arrays. Received December 23, 1997, and in final form September 9, 1998.     

Multi-objective optimization of the light guide rod by using the combined Taguchi method and Grey relational approach

The light guide rod (LGR) is widely used to transmit light from a light emitting diode lamp. In this paper, a designed LGR for the application in the automobile lighting is prepared. The main factors that affect the LGR performances are the illuminance flux and uniformity. This paper aims to develop a method that optimizes the multi-objective parameters of the LGR. For statistical purposes, the experimental parameters for the LGRs are put in the L ₉(3⁴) orthogonal array. In order to optimize these parameters, a method combining Taguchi method and Grey relational approach is established. The experimental results from illuminance flux and uniformity can be integrated into a single performance index. A comparison of the integrated performance index between the initial and optimal conditions shows that the illuminance flux increases from 1.14 to 1.42(lm) and the average difference from 1.46 to 1.07. The positive gains for the illuminance flux and the average difference value by this approach and compared with the initial condition are reported as 25.04 and 26.64 %, respectively.     

Evaluating the effect of diffuse light on photometric stereo reconstruction

Photometric stereo surface reconstruction requires each input image to be associated with a particular 3D illumination vector. This signifies that the subject should be illuminated in turn by various directional illumination sources. In real life, this directionality may be reduced by ambient illumination, which is typically present as a diffuse component of the incident light. This work assesses the photometric stereo reconstruction quality for various ratios of ambient to directional illuminance and provides a reference for the robustness of photometric stereo with respect to that illuminance ratio. In our analysis, we focus on the face reconstruction application of photometric stereo, as faces are convex objects with rich surface variation, thus providing a suitable platform for photometric stereo reconstruction quality evaluation. Results demonstrate that photometric stereo renders realistic reconstructions of the given surface for ambient illuminance as high as nine times the illuminance of the directional light component.     

Positive display polarity is advantageous for both younger and older adults

The effect of display polarity on visual acuity and proofreading performance was investigated for younger and older adults. An advantage of positive polarity (dark characters on light background) over negative polarity (light characters on dark background) was expected for younger adults, but the effects on older adults were ambiguous. Light scatter due to residues in the senescent lens and vitreous humour could reverse the typical advantage of positive polarity. However, age-related changes lead to a decline in retinal illuminance. Brighter positive polarity displays should help to compensate for this decline and, accordingly, lead to better performance than darker negative polarity displays. Participants conducted a visual acuity test with black optotypes on white background or white optotypes on black background and performed a proofreading task in the same polarity. A positive polarity advantage was found for both age groups. The presentation in positive polarity is recommended for all ages.

Practitioner summary: In an ageing society, age-related vision changes need to be considered when designing digital displays. Visual acuity testing and a proofreading task revealed a positive polarity advantage for younger and older adults. Dark characters on light background lead to better legibility and are strongly recommended independent of observer's age.     

Roll‐to‐roll UV embossing process applied for light bar‐based sub‐wavelength gratings for backlight

This study proposes a roll‐to‐roll process‐based sub‐wavelength grating, which is attached on a light bar to turn the side‐lit red/green/blue (620, 520, and 450 nm) incident rays into a uniformly and normally output white light with high illuminance from the light bar's surface. On the basis of the rigorous coupling wave analysis, the relationship between the first‐order transmission/reflection efficiency and the pitch of the gratings with different shapes was analyzed. The optimal design can effectively reduce the coupling length and enhance the white color balance for display applications.