Unravelling in Two-Sided Matching Markets and Similarity of Preferences

This paper investigates the causes and welfare consequences of unravelling in two-sided matching markets. It shows that similarity of preferences is an important factor driving unravelling. In particular, it shows that under the ex-post stable mechanism (the mechanism that the literature focuses on), unravelling is more likely to occur when participants have more similar preferences. It also shows that any Pareto-optimal mechanism must prevent unravelling, and that the ex-post stable mechanism is Pareto-optimal if and only if it prevents unravelling.two-sided matching, unravelling, similarity of preferences

Interaction of an Eulerian flue gas plume with wind turbines

The reduced availability of sites with the requisite wind resource, planning permission and public acceptance for the placement of wind turbines poses a significant challenge to future expansion of the wind energy industry. Developers increasingly wish to site large turbines in close proximity to industrial plants, but there is uncertainty amongst environmental protection agencies on how best to measure and regulate the impact that wind turbines may have on the dispersion of the gases that are often emitted into the atmosphere from such plants. Several simplified wind turbine-flue stack configurations have been simulated using the Vorticity Transport Model. This model provides a high-fidelity representation of the vortical flow structure within both the wind turbine wake and the plume, and is able to capture the re-direction and dispersion of the plume that occurs due to interaction with the wind turbine. The impingement of the plume on the wind turbine is shown to disrupt the wake structure downwind of the wind turbine, and may induce additional unsteady loading on the turbine rotor. The velocity deficit downwind of the wind turbine influences the rate at which the plume propagates downwind, and results in an increase in the concentration of plume material (which may include pollutant gas and particulates) around the wind turbine. This localized increase in plume concentration is shown to be sensitive to the thrust coefficient at which the wind turbine is operated. The results presented in this paper show that environmental protection agencies are justified in their concerns regarding the placement of wind turbines near to industrial plants, and suggests strongly that the interaction between wind turbines and gas plumes should be investigated further

libcloudph++ 0.2: single-moment bulk, double-moment bulk, and particle-based warm-rain microphysics library in C++

This paper introduces a library of algorithms for representing cloud microphysics in numerical models. The library is written in C++, hence the name libcloudph++. In the current release, the library covers three warm-rain schemes: the single- and double-moment bulk schemes, and the particle-based scheme with Monte-Carlo coalescence. The three schemes are intended for modelling frameworks of different dimensionality and complexity ranging from parcel models to multi-dimensional cloud-resolving (e.g. large-eddy) simulations. A two-dimensional prescribed-flow framework is used in example simulations presented in the paper with the aim of highlighting the library features. The libcloudph++ and all its mandatory dependencies are free and open-source software. The Boost.units library is used for zero-overhead dimensional analysis of the code at compile time. The particle-based scheme is implemented using the Thrust library that allows to leverage the power of graphics processing units (GPU), retaining the possibility to compile the unchanged code for execution on single or multiple standard processors (CPUs). The paper includes complete description of the programming interface (API) of the library and a performance analysis including comparison of GPU and CPU setups.Comment: The library description has been updated to the new library API (i.e. v0.1 -> v0.2 update). The key difference is that the model state variables are now mixing ratios as opposed to densities. The particle-based scheme was supplemented with the "particle recycling" process. Numerous editorial corrections were mad

Ultrasonic detection of flaws in fusion butt welds

Reliable and accurate Delta technique, a nondestructive ultrasonics method, uses redirection of energy to detect randomly oriented imperfections in fusion butt welds. Data on flaws can be read from either an oscilloscope or a printout

A survey of the problem and research needs in the coastal zone

Coastal zone oceanography emphasizing pollution and geological processes - bibliograph

Thermal degradation of citrus pectin in low-moisture environment - Influence of acidic and alkaline pre-treatment

Pectin powder is degraded during storage and transport by demethoxylation and depolymerisation. The degradation mechanisms and especially the influence of pre-treatments on the degradation reactions are not completely understood. In this study, commercial citrus pectin was modified by either acidic or alkaline demethoxylation. The modified pectins, as well as the commercial pectin, were thermally degraded during four weeks of storage at 60 °C and 80% relative humidity. Demethoxylation and depolymerisation as well as colour alterations were examined during degradation, and the course of the reactions was monitored. It was found that the type of pre-treatment during modification determined the material properties and, thus, the water uptake of the modified pectin powders. The resulting water availability in the samples was crucial to the extent of demethoxylation and to the type and intensity of depolymerisation since some of these reactions competed for the water in the climate chamber. The pre-treatment also determined the content of neutral sugars and sodium ions of the modified pectins. High contents of these components limited the extent of degradation in different ways. A previously assumed third depolymerisation mechanism of pectins, beside backbone hydrolysis and β-elimination, was confirmed.DFG, 268547215, Strukturabhängige Abbaureaktionen von Pektinen und deren Auswirkungen auf nicht-enzymatische Bräunung und technologische Funktionalitä

Experience of shocks, household wealth and expectation formation: Evidence from smallholder farmers in Kenya

When faced with uncertain events, decision‐makers form expectations about the events’ likelihood of occurrence. However, the drivers and moderators of such expectations are still poorly understood, especially for farm decision‐makers in developing countries whose incomes are very risky by nature. This article analyses the dynamic shock expectation formation process of farmers in Kenya with regard to a range of shock events using a unique panel dataset. The results suggest that farmers are more likely to update their expectation regarding a specific adverse shock when they have recently been affected by that shock or by more shocks in general. In case of price shocks, farmers are also more likely to update expectations when a larger proportion of fellow village members was affected. However, household wealth moderates the relationship between shock expectation and experience, such that wealthier households are less likely to update their expectations following a shock. A better understanding of the drivers of expectation formation can help in the design of better risk management instruments that increase farmers’ resilience.Peer Reviewe