Magnifying image intensifier

A magnetically focused image intensifier was improved to increase the usable range of magnification without degradation of image quality. The power requirements of the focusing coils are minimal. The arrangement of the focusing coils reverses the direction of the axial magnetic field distribution between the planes of the photocathode and the phosphor screen

Declining Volatility in the U.S. Automobile Industry

This paper documents the dramatic changes in volatility that occurred in the U.S. auto industry in the early 1980s. Namely, output volatility declined significantly, the covariance of inventory investment and sales became much more negative, and adjustments to output, which in earlier decades stemmed primarily from plants hiring and laying off workers, were more often accomplished with changes in average hours per worker after the mid 1980s. Building on the work of Blanchard (1983), we show how all of these changes could have stemmed from one underlying factor%u2014a decline in the persistence of motor vehicle sales. We use both industry-level data as well as micro data on production schedules from 103 assembly plants in the United States and Canada to document the developments in the early 1980s. We then use the original Holt, Modigliani, Muth and Simon (1960) linear quadratic inventory model to show how a decline in the persistence of sales leads to all of the changes noted above, including the propensity to use intensive margins of adjustment over extensive labor margins, even in the absence of technological change.

Why Do Real and Nominal Inventory-Sales Ratios Have Different Trends

This note explains the diverging trends between real and nominal aggregate inventory-sales ratios. The combined effect of two features of the data explains the divergence. First, while aggregate sales include both goods and services, inventories include only goods. Second, there has been a strong secular decrease in the relative price of goods. The combination of these two factors causes the real and nominal aggregate inventory-sales ratios to have different trends.

Tracking the Source of the Decline in GDP Volatility: An Analysis of the Automobile Industry

Recent papers by Kim and Nelson (1999) and McConnell and Perez-Quiros (2000) uncover a dramatic decline in the volatility of U.S. GDP growth beginning in 1984. Determining whether the source is good luck, good policy or better inventory management has since developed into an active area of research. This paper seeks to shed light on the source of the decline in volatility by studying the behavior of the U.S. automobile industry, where the changes in volatility have mirrored those of the aggregate data. We find that changes in the relative volatility of sales and output, which have been interpreted by some as evidence of improved inventory management, are in fact the result of changes in the process driving automobile sales. We first show that the autocorrelation of sales dropped during the 1980s, and that the behavior of interest rates may be the force behind the change in sales persistence. A simulation of the assembly plants' cost function illustrates that the persistence of sales is a key determinant of output volatility. A comparison of the ways in which assembly plants scheduled production in the 1990s relative to the 1970s supports the intuition of the simulation.

Electronic magnification for astronomical camera tubes

Definitions, test schemes, and analyses used to provide variable magnification in the image section of the television sensor for large space telescopes are outlined. Experimental results show a definite form of magnetic field distribution is necessary to achieve magnification in the range 3X to 4X. Coil systems to establish the required field shapes were built, and both image intensifiers and camera tubes were operated at high magnification. The experiments confirm that such operation is practical and can provide satisfactory image quality. The main problem with such a system was identified as heating of the photocathode due to concentration of coil power dissipation in that vicinity. Suggestions for overcoming this disadvantage are included

Anxiety, Attention and Performance Variability in Visuo-motor Skills

The aims of the current program of research were to examine the impact of anxiety on performance and attentional control during the execution of two far aiming tasks, and to examine the efficacy of gaze training interventions in mediating these effects. Attentional control theory (ACT), which suggests that anxious individuals have impaired goal-directed attentional control, was adopted as a theoretical framework, and the Quiet Eye, characterised by long final fixations on relevant locations, was adopted as an objective measure of overt attentional control. In Studies 1 and 2 increased pressure impaired goal directed attentional control (QE) at the expense of stimulus-driven control (more fixations of shorter duration to various targets). The aim of studies 3 and 4 was therefore to examine the efficacy of an intervention designed to train effective visual attentional control (QE training) for novices, and determine whether such training protected against attentional disruptions associated with performing under pressure. In both studies the QE trained group maintained more effective visual attentional control and performed significantly better in a subsequent pressure test compared to the Control group, providing support for the efficacy of attentional training for visuo-motor skills. The aim of study 5 was to examine the effectiveness of a brief QE training intervention for elite golfers and to examine if potential benefits shown for novices in studies 3 and 4 transferred to competitive play. The QE-trained group maintained their optimal QE and performance under pressure conditions, whereas the control group experienced reductions in QE and performance. Importantly, these advantages transferred to the golf course, where QE-trained golfers reduced their putts per round by 1.9 putts, compared to pre-training, whereas the control group showed no change in their putting statistics. This series of studies has therefore implicated the role of attention in the breakdown of performance under pressure, but has also suggested that visual attentional training regimes may be a useful technique for alleviating this problem

The Ultrasonic Detection of Environmental Degradation in Adhesive Joints

There are many benefits to be gained when using adhesives compared with the use of more traditional joining techniques. Amongst these advantages can be listed the ability to join dissimilar materials, the uniform distribution of load over the area of the joint avoiding stress concentrations, the improvement in aesthetics and, potentially, a lower-weight for the component or structure. However several factors have retarded the more widespread use of adhesives. These principally are (i) the detrimental effect of moisture on the joint strength and (ii) the lack of a suitable non-destructive testing technique for detecting strength loss due to environmental attack. It is the latter problem that the present work addresses. The focus of this work has been to examine the bonding of aluminium alloy to aluminium alloy, using an epoxy-based adhesive