3,005 research outputs found

    Kate's Model Verification Tools

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    Kennedy Space Center's Knowledge-based Autonomous Test Engineer (KATE) is capable of monitoring electromechanical systems, diagnosing their errors, and even repairing them when they crash. A survey of KATE's developer/modelers revealed that they were already using a sophisticated set of productivity enhancing tools. They did request five more, however, and those make up the body of the information presented here: (1) a transfer function code fitter; (2) a FORTRAN-Lisp translator; (3) three existing structural consistency checkers to aid in syntax checking their modeled device frames; (4) an automated procedure for calibrating knowledge base admittances to protect KATE's hardware mockups from inadvertent hand valve twiddling; and (5) three alternatives for the 'pseudo object', a programming patch that currently apprises KATE's modeling devices of their operational environments

    Automatically calibrating admittances in KATE's autonomous launch operations model

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    This report documents a 1000-line Symbolics LISP program that automatically calibrates all 15 fluid admittances in KATE's Autonomous Launch Operations (ALO) model. (KATE is Kennedy Space Center's Knowledge-based Autonomous Test Engineer, a diagnosis and repair expert system created for use on the Space Shuttle's various fluid flow systems.) As a new KATE application, the calibrator described here breaks new ground for KSC's Artificial Intelligence Lab by allowing KATE to both control and measure the hardware she supervises. By automating a formerly manual process, the calibrator: (1) saves the ALO model builder untold amounts of labor; (2) enables quick repairs after workmen accidently adjust ALO's hand valves; and (3) frees the modeler to pursue new KATE applications that previously were too complicated. Also reported are suggestions for enhancing the program: (1) to calibrate ALO's TV cameras, pumps, and sensor tolerances; and (2) to calibrate devices in other KATE models, such as the shuttle's LOX and Environment Control System (ECS)

    Market Power and Relative Price Adjustment: Evidence from the UK

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    Empirical studies of price transmission often suggest that imperfect pass-through may be due to market power exerted by food retailers. However, these econometric studies essentially lack any formal basis for tying the role of market power with data comprising of retail and producer prices only. We show that if market power has an effect on the farm-retail margin, this determines the specification of the cointegrating relationship. To emphasise the relevance of the tests, we focus on results relating the UK beef sector and show that market power is likely to have played a role in determining the retail-farm price margin.price adjustment, market power, Demand and Price Analysis, Q11, L13,

    The will-o\u27-the-wisp of the plains in Wright Morris\u27 works

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    Today the wind rushes over the tablelands of Nebraska as it did when the Buffalo, standing knee-deep in Prairie grass and stretching farther then eye-length, turn their shaggy tails to windward. Only now corn rustles, cattle imitate the Buffalo, in the occasional grain elevator, white and monolithic, forces the wind to adjust its otherwise unrestrained course. Small towns, like islands in a sea of plain, have rooted into the soil, and the wind moves easily around them. Such a small town is Central City, and there such a writer as Wright Morris was born. This was in 1910, 20 years after the frontier in America was declared closed, and three years before Willa Cather published O Pioneers!

    Do Sales Matter? Evidence from UK Food Retailing

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    This paper assesses the role of sales as a feature of price dynamics using scanner data. The study analyses a unique, high frequency panel of supermarket prices consisting of over 230,000 weekly price observations on around 500 products in 15 categories of food stocked by the UK’s seven largest retail chains. In all, 1,700 weekly time series are available at the barcode-specific level including branded and own-label products. The data allows the frequency, magnitude and duration of sales to be analysed in greater detail than has hitherto been possible with UK data. The main results are: (i) sales are a key feature of aggregate price variation with around 40 per cent of price variation being accounted for by sales once price differences for each UPC level across the major retailers are accounted for; (ii) much of the price variation that is observed in the UK food retailing sector is accounted for by price differences between retailers; (iii) only a small proportion of price variation that is observed in UK food retailing is common across the major retailers suggesting that cost shocks originating at the manufacturing level is not one of the main sources of price variation in the UK; (iv) own-label products also exhibit considerable sales behaviour though this is less important than sales for branded goods; and (v) there is some evidence of coordination in the timing of sales across retailers insofar as the probability of a sale at the UPC level at a given retailer increases if the product is also on sale at another retailer.Sales, price variation, retail, Consumer/Household Economics, Demand and Price Analysis, L16, L66, Q13.,

    Buyer power in U.K. food retailing: a 'first-pass' test

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    Habtu Weldegebriel, University of Warwick Abstract The potential existence of buyer power in U.K. food retailing has attracted the scrutiny of the U.K.'s anti-trust authorities, culminating in the second of two comprehensive regulatory inquiries in recent years. Such inquiries are authoritative but correspondingly time-consuming and costly. Moreover, detection of buyer power has been dogged by the paucity of reliable evidence of its existence. In this paper, we present a simple theoretical model of oligopsony which delivers quasi-reduced form retailer-producer pricing equations with which the null of perfect competition can be tested using readily available market data. Using a cointegrated vector autoregression, we find empirical results that show the null of perfect competition can be rejected in seven of the nine food products investigated. Though not conclusive on the existence of buyer power, the proposed test offers a means via which the behaviour of the retail-producer price spread is consistent with it. At the very least, it can corroborate the concerns of the anti-trust authorities as to whether buyer power is potentially one source of concern

    Buyer Market Power in UK Food Retailing

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    The potential existence of buyer market power in UK food retailing has attracted the scrutiny of the UK's anti-trust authorities, culminating in the decision to launch the second of two comprehensive regulatory inquiries in recent years. Throughout, detection of buyer power has been dogged by the paucity of reliable evidence of its existence. In this paper we present a simple theoretical model of oligopsony which delivers quasireduced form retailer-producer pricing equations in which the presence of market power can be detected using readily available market data. Using a cointegrated vector autoregression, we find empirical results that are consistent with the presence of oligopsony power in all six food products investigated.Buyer power, Cointegrated VARs, UK food industry, Agribusiness, Consumer/Household Economics,
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