Patterns of Trade in the Market for Used Durables: Theory and Evidence

The consumption value of a durable good diminishes as it ages due to physical deterioration and consumers' preference for the new. We develop a model of consumer specialization and trade in the market for used durables based on imperfect substitutability. Imperfect substitutability across vintages is reflected in a declining market price over time. Heterogeneous consumers maximize utility by specializing in durables of differing ages. Consumers must trade to acquire their preferred vintage each period. When there are transaction costs in the secondhand market, the volume of trade due to specialization increases with imperfect substitutability. We examine the determinants of vehicle ownership transfers in Illinois, a measure of trade volume. Observed patterns of trade across automobile model years are consistent with our model, and inconsistent with a model of adverse selection.

Scene Coordinate Regression with Angle-Based Reprojection Loss for Camera Relocalization

Image-based camera relocalization is an important problem in computer vision and robotics. Recent works utilize convolutional neural networks (CNNs) to regress for pixels in a query image their corresponding 3D world coordinates in the scene. The final pose is then solved via a RANSAC-based optimization scheme using the predicted coordinates. Usually, the CNN is trained with ground truth scene coordinates, but it has also been shown that the network can discover 3D scene geometry automatically by minimizing single-view reprojection loss. However, due to the deficiencies of the reprojection loss, the network needs to be carefully initialized. In this paper, we present a new angle-based reprojection loss, which resolves the issues of the original reprojection loss. With this new loss function, the network can be trained without careful initialization, and the system achieves more accurate results. The new loss also enables us to utilize available multi-view constraints, which further improve performance.Comment: ECCV 2018 Workshop (Geometry Meets Deep Learning

Limited-area short-range ensemble predictions targeted for heavy rain in Europe

International audienceInherent uncertainties in short-range quantitative precipitation forecasts (QPF) from the high-resolution, limited-area numerical weather prediction model DMI-HIRLAM (LAM) are addressed using two different approaches to creating a small ensemble of LAM simulations, with focus on prediction of extreme rainfall events over European river basins. The first ensemble type is designed to represent uncertainty in the atmospheric state of the initial condition and at the lateral LAM boundaries. The global ensemble prediction system (EPS) from ECMWF serves as host model to the LAM and provides the state perturbations, from which a small set of significant members is selected. The significance is estimated on the basis of accumulated precipitation over a target area of interest, which contains the river basin(s) under consideration. The selected members provide the initial and boundary data for the ensemble integration in the LAM. A second ensemble approach tries to address a portion of the model-inherent uncertainty responsible for errors in the forecasted precipitation field by utilising different parameterisation schemes for condensation and convection in the LAM. Three periods around historical heavy rain events that caused or contributed to disastrous river flooding in Europe are used to study the performance of the LAM ensemble designs. The three cases exhibit different dynamic and synoptic characteristics and provide an indication of the ensemble qualities in different weather situations. Precipitation analyses from the Deutsche Wetterdienst (DWD) are used as the verifying reference and a comparison of daily rainfall amounts is referred to the respective river basins of the historical cases

Modeling Micro-Porous Surfaces for Secondary Electron Emission Control to Suppress Multipactor

This work seeks to understand how the topography of a surface can be engineered to control secondary electron emission (SEE) for multipactor suppression. Two unique, semi-empirical models for the secondary electron yield (SEY) of a micro-porous surface are derived and compared. The first model is based on a two-dimensional (2D) pore geometry. The second model is based on a three-dimensional (3D) pore geometry. The SEY of both models is shown to depend on two categories of surface parameters: chemistry and topography. An important parameter in these models is the probability of electron emissions to escape the surface pores. This probability is shown by both models to depend exclusively on the aspect ratio of the pore (the ratio of the pore height to the pore diameter). The increased accuracy of the 3D model (compared to the 2D model) results in lower electron escape probabilities with the greatest reductions occurring for aspect ratios less than two. In order to validate these models, a variety of micro-porous gold surfaces were designed and fabricated using photolithography and electroplating processes. The use of an additive metal-deposition process (instead of the more commonly used subtractive metal-etch process) provided geometrically ideal pores which were necessary to accurately assess the 2D and 3D models. Comparison of the experimentally measured SEY data with model predictions from both the 2D and 3D models illustrates the improved accuracy of the 3D model. For a micro-porous gold surface consisting of pores with aspect ratios of two and a 50% pore density, the 3D model predicts that the maximum total SEY will be one. This provides optimal engineered surface design objectives to pursue for multipactor suppression using gold surfaces

Werbenutzen einer unterhaltenden Website : eine Untersuchung am Beispiel der Moorhuhnjagd

Jedes Jahr steigt die Zahl der Internet-Nutzer, in Deutschland sind es mittlerweile 19,5 Millionen. Als Konsequenz können immer mehr Menschen von Unternehmen über das Internet erreicht werden. Das Schlagwort des e-Commerce beherrscht die Diskussion. Aber auch Unternehmen, die das Internet nicht als Handelsplattform verwenden, sind im Internet mit eigenen Homepages präsent. Sie nutzen es zur Kommunikationspolitik. Dabei ist bei zu Werbezwecken designten Homepages der werbliche Kommunikationsprozess im Vergleich zu den klassischen Medien umgedreht. Der User wird nicht passiv von einem Unternehmen mit Werbung "berieselt", sondern muss eine Seite aktiv aufrufen. Dies tut er nur, wenn er sich hiervon einen Nutzen verspricht. Im Fall von High-Involvement Produkten zieht er einen Informationsnutzen aus einer entsprechend informativen Homepage. Bei Low-Involvement Produkten sucht der Konsument nicht nach Informationen. Er besucht eine Homepage nur, wenn er einen Unterhaltungsnutzen erwartet. Wechselt man die Perspektive vom Nachfrager zum Anbieter, stellt sich die bis dato noch nicht durch eine empirische Untersuchung beantwortete Frage, was für Vorteile ein Unternehmen aus der Bereitstellung einer unterhaltenden Werbe­homepage ziehen kann. Als relevante Werbeziele wurden die Steigerung der aktiven Markenbekanntheit, die Veränderung des Image, der Aufbau neuer und lebendiger Markenbilder sowie eine Erhöhung der Kaufabsicht untersucht. Um Veränderungen nachweisen zu können, wurden zwei Gruppen befragt. Eine Gruppe hatte das Internet-Spiel Moorhuhnjagd von Johnnie Walker, das als beispielhafter Inhalt einer unterhaltenden Werbehomepage gelten kann, gespielt, die andere nicht. Spieler nehmen das Image dieser Marke signifikant trendgemäßer wahr und haben lebendigere innere Bilder zu Johnnie Walker als Nicht-Spieler. Das Moorhuhn konnte innerhalb kurzer Zeit als neues Markenbild etabliert werden

A new BIST scheme for low-power and high-resolution DAC testing

A BIST scheme for testing on chip DAC is presented in this paper. We discuss the generation of on chip testing stimuli and the measurement of digital signals with a narrow-band digital filter. We validate the scheme with software simulation and point out the possibility of ADC BIST with verified DACicus-journals

Квир-лингвистика: нужна ли она отечественной лингвистической гендерологии?

Статья посвящена квир-лингвистике как новому магистральному направлению развития современной парадигмы гендерных исследований. Подробно разбирается концептуальный аппарат этого направления. Описывается попытка изучения фрагментов языкового сознания носителей русского языка с учетом квир-фактора.Стаття присвячена квір-лінгвістиці як новому магістральному напрямку в розвитку сучасної парадигми гендерних досліджень. Докладно розбирається концептуальний апарат цього напрямку. Описується спроба вивчення фрагментів мовної свідомості носіїв російської мови з урахуванням квір-фактору.The article is targeted at a new discipline in the area of gender and language research – queer linguistics. The conceptual linguistic apparatus and terminology are discussed. The study of verbal responses obtained from Russian –speaking informants (gays and lesbians) as a linguistic construal of their world is analyzed