The interaction of chromostereopsis and stereopsis in stereoscopic CRT displays

To give operators of high-speed, highly-manoeuvrable vehicles the ability to keep pace with their increasingly dynamic environment, stereoscopic 3-D displays may soon replace conventional 2-D displays. Important to the development of stereoscopic 3-D displays is the interaction of perceived depth created by hues (chromostereopsis) and perceived depth created by presenting different images of a single object to the left and right eye of the observer (stereopsis). The purpose of this research is to evaluate the interaction of chromostereopsis and stereopsis on a stereoscopic CRT by determining the level of accuracy with which subjects can properly interpret the relative depth differences of adjacent symbols containing six levels of hue and seven levels of stereoscopic disparity. This research demonstrated that hue, disparity, and the interaction of hue and disparity significantly influenced one's perception of depth on a stereoscopic monitor. The results suggest that caution should be exercised by the stereoscopic 3-D display format designer when choosing hues to represent images located in close proximity on a stereoscopic display. Due to the chromostereoscopic effect on the perception of depth, hues on extreme ends of the colour spectrum should not be used in situations where less than 3.39 arc minutes of disparity difference is being portrayed on a stereoscopic display, unless the hues are consistently being used to alter the depth presented by stereoscopic disparity, or the chromostereoscopic depth resulting from certain hues is consistently nullified by altering disparity levels accordingly.     

Estimating meme fitness in adaptive memetic algorithms for combinatorial problems

Among the most promising and active research areas in heuristic optimisation is the field of adaptive memetic algorithms (AMAs). These gain much of their reported robustness by adapting the probability with which each of a set of local improvement operators is applied, according to an estimate of their current value to the search process. This paper addresses the issue of how the current value should be estimated. Assuming the estimate occurs over several applications of a meme, we consider whether the extreme or mean improvements should be used, and whether this aggregation should be global, or local to some part of the solution space. To investigate these issues, we use the well-established COMA framework that coevolves the specification of a population of memes (representing different local search algorithms) alongside a population of candidate solutions to the problem at hand. Two very different memetic algorithms are considered: the first using adaptive operator pursuit to adjust the probabilities of applying a fixed set of memes, and a second which applies genetic operators to dynamically adapt and create memes and their functional definitions. For the latter, especially on combinatorial problems, credit assignment mechanisms based on historical records, or on notions of landscape locality, will have limited application, and it is necessary to estimate the value of a meme via some form of sampling. The results on a set of binary encoded combinatorial problems show that both methods are very effective, and that for some problems it is necessary to use thousands of variables in order to tease apart the differences between different reward schemes. However, for both memetic algorithms, a significant pattern emerges that reward based on mean improvement is better than that based on extreme improvement. This contradicts recent findings from adapting the parameters of operators involved in global evolutionary search. The results also show that local reward schemes outperform global reward schemes in combinatorial spaces, unlike in continuous spaces. An analysis of evolving meme behaviour is used to explain these findings.     

A theoretical approach for inverse filter design in ultrasonic applications

A comparison between simulation- and measurement-based characterization is provided for the design of one-dimensional, nonadaptive, inverse filters for ultrasonic applications. Both prefiltering and postfiltering are considered by means of two different filtering strategies performed in the time and frequency domains. The results clearly indicate that theoretical methods can be used successfully, provided that the physical limitations of the simulation process are fully appreciated. In some instances, the simulation-based approach is shown to provide superior results, and the reasons for this are explained.     

Quantitative real-time imaging of myocardium based on ultrasonic integrated backscatter

The integrated backscatter calculation over the full, two-dimensional echocardiographic sector is implemented to produce images from closed-chest dogs. This new real-time integrated backscatter measurement system allows a continuous determination of integrated backscatter from all myocardial regions in the ultrasonic view. By replacing the conventional video processor in a commercial two-dimensional echocardiographic imager with this new real-time backscatter measurement system, it is possible to produce real-time two-dimensional images based on integrated backscatter.     

Clinical biochemistry and pathology of mature beef cattle following ante-mortem intravenous administration of a commercial papain preparation

Ten healthy beef cattle in a commercial abbatoir were treated intravenously before slaughter with a commercial papain-based tenderising injection (Pro Ten). Animals were observed for behavioural and clinical abnormalities following treatment. Serum enzyme activities were measured pre-treatment and post-treatment immediately pre-slaughter < 6 min later to detect liver and muscle damage. Carcases were examined grossly post mortem. Histological examination of liver, kidney and muscle followed. Nine contemporary, age-matched controls were similarly examined. It was concluded that ProTen treatment did not cause any detectable hepatocellular or renal damage and there was no significant difference in the parameters examined between treated and untreated cattle. A decision to ban the use of ProTen in cattle could not therefore be based on the premise that it interfered with the animal's welfare in the period following injection under the conditions pertaining in this experiment.     

Vibration in car repair work

The main objective of the study was to find efficient hand tools which caused only minor vibration loading. Vibration measurements were carried out under standardised working conditions. The time during which car body repairers in seven companies were exposed to vibration was determined. Chisel hammers, impact wrenches, sanders and saws were the types of tools which generated the highest vibration accelerations. The average daily exposure at the different garages ranged from 22 to 70 min. The risk of vibration injury is currently rated as high. The difference between the highest and lowest levels of vibration was considerable in most tool categories. Therefore the choice of tool has a major impact on the magnitude of vibration exposure. The importance of choosing the right tools and working methods is discussed and a counselling service on vibration is proposed.