1,157 research outputs found
Satisfaction not Guaranteed - Institutions and Satisfaction with Democracy in Western Europe
What determines citizens’ satisfaction with the “constitution in operation”? We make two contributions towards an answer to this important policy question. First, we place stronger emphasis than existing studies on quantitative interpretations of the importance of different factors. We use scenario analysis to show that a consensual system generally promotes satisfaction, but affects different types of citizens differently. Second, we focus on informal institutions and rules of the game in European societies. Corporatism and group membership as a measure of social capital are good for satisfaction, and people who live in countries with a high degree of income inequality tend to be less satisfied. The findings for trust and for the rule of law are ambiguous.satisfaction with democracy, political economy, institutions
Technik der latenten Wärmespeicherung : eine Übersicht
Die Technik der latenten Wärmespeicherung ist keine neue Technologie, im Gegenteil, sie ist seit langer Zeit bekannt und wird eben solange erforscht. Warum hat sich diese Technologie dennoch bis heute nicht durchgesetzt, trotz der doch so offensichtlichen Vorteile?
Damit diese Frage beantwortet werden kann, muss zuerst die Technologie an sich verstanden werden. Das bedeutet: Verstehen, welchen Naturgesetzen diese Technologie unterliegt und wie diese Speicherart und damit verbunden, ihre Leistungsfähigkeit beeinflusst werden kann. Aus diesem Grund wird die Technologie an dieser Stelle ganzheitlich vorgestellt. Dazu gehören die Einsortierung in die bekannten thermischen Energiespeichermethoden und ergänzende Erklärungen über ihre Funktionsweise, die Anforderungen an die verbauten Materialien, die Stoffe und deren Stoffgrössen und die aktuellen Anwendungsgebiete. Um die Thematik abzurunden wurden Messungen an einem stark vereinfachten, eigens gebauten Latentwärmespeichermodell durchgeführt und interpretiert.
Temperaturmessungen im und am Modellspeicher haben gezeigt, dass ein gut durchdachtes Speicherkonzept enorm wichtig ist. Ein Konzept, welches die Vorteile der Technologie in den Vordergrund stellt und diese auch nutzen kann. Diese Vorteile sind höhere spezifische Speicherkapazitäten als sensible Wärmespeicher, eine Auskopplung der Wärme bei einer konstanten Temperatur, die Möglichkeit die gesamte gespeicherte Wärmeenergie auszukoppeln, sowie die Möglichkeit der Langzeitspeicherung von Wärme. Dafür müssen verschiedene Bedingungen erfüllt sein.
Eine optimale Wärmeübertragung vom Speichermaterial auf das zu erwärmende Fluid muss gewährleistet werden. Dabei ist die Konstruktion des Wärmetauschers entscheidend. Dies wird bei der Versuchsauswertung des stark vereinfachten Modells deutlich, welches eine schlechte Wärmeübertragung aufweist. Die Energiedichte der heutigen Speichermaterialien ist zu gering. Diese müsste, vor allem für eine Langzeitspeicherung (Sommer/Winter), grösser sein. Die benötigte Menge an Speichermaterial und die Grösse der Latentwärmespeicher könnte dadurch reduziert werden, was ebenfalls einen positiven Einfluss auf die Anschaffungskosten bedeuten würde.
Das Potenzial solcher Anlagen wird in naher Zukunft als gering eingeschätzt, da viele Fakten gegen diese Technik für Langzeitspeicherung sprechen. Diese Technologie hat nur eine Chance, wenn im Bereich der Speichermaterialien ein Durchbruch gelingt. Es wird klar, dass sich die Anwendung des Latentwärmespeichers in Richtung Kurzzeitspeicher (Tag/Nacht) verschieben muss
Semi-classical description of matter wave interferometers and hybrid quantum systems
This work considers the semi-classical description of two applications involving cold atoms. This is, on one hand, the behavior of a BOSE-EINSTEIN condensate in hybrid systems, i.e. in contact with a microscopic object (carbon nanotubes, fullerenes, etc.). On the other, the evolution of phase space distributions in matter wave interferometers utilizing ray tracing methods was discussed.
For describing condensates in hybrid systems, one can map the GROSS-PITAEVSKII equation, a differential equation in the complex-valued macroscopic wave function, onto a system of two differential equations in density and phase. Neglecting quantum dispersion, one obtains a semiclassical description which is easily modified to incorporate interactions between condensate and microscopical object. In our model, these interactions comprise attractive forces (CASIMIR-POLDER forces) and loss of condensed atoms due to inelastic collisions at the surface of the object. Our model exhibited the excitation of sound waves that are triggered by the object’s
rapid immersion, and spread across the condensate thereafter. Moreover, local particle loss leads to a shrinking of the bulk condensate. We showed that the total number of condensed particles
is decreasing potentially in the beginning (large condensate, strong mean field interaction), while it decays exponentially in the long-time limit (small condensate, mean field inetraction
negligible).
For representing the physics of matter wave interferometers in phase space, we utilized the WIGNER function. In semi-classical approximation, which again consists in ignoring the quantum
dispersion, this representation is subject to the same equation of motion as classical phase space distributions, i.e. the LIOUVILLE equation. This implies that time evolution of theWIGNER function
follows a phase space flow that consists of classical trajectories (classical transport). This means, for calculating a time-evolved distribution, one has know the initial distribution and one has to
solve the classical equations of motion.
Concerning the initial distribution, we have studied a stationary solution of the nonlinear LIOUVILLE equation, the LAMBERT density. We saw that it agrees very well with results from singleparticle quantum mechanics as well as the MAXWELL-BOLTZMANN distribution in the weakly interacting limit. Likewise, in the strongly interacting limit, familiar results of the THOMAS-FERMI approximation are recovered. A distribution that is first prepared in a trap and then released can be described quite conveniently in terms of WIGNER functions. However, propagation in optical potentials associated to the interferometer elements (beam splitter, Pi-half-pulse) do not satisfy the condition of the semiclassical
approximation. Nevertheless, one finds discrete before-after mappings that describe the effect of these elements on incident distributions. This leads to several channels of phase space propagation which relate to the interferometer paths and interferences between them.
The formalism for WIGNER functions in an interferometer can be translated straightforwardly into a ray tracing algorithm. As mentioned above, this algorithm solves the classical equations
of motion and computes time-evolved distributions, using values of the initial distribution. This procedure, in contrast to most analytical solutions, does not require the HAMILTON function to
be quadratic (e.g. free propagation, const. acceleration, harmonic oscillator). We compared simulation results to analytic expressions in case of freely propagating GAUSS distribution. They showed perfect agreement, especially for the functional dependence of wave length and contrast of interference fringes on the laser pulse timings
Optimizing 3D object detection for embedded systems in automated vehicles using sensor data fusion and CUDA computing
Signals of recent spatial expansions in the grey mouse lemur (Microcebus murinus)
<p>Abstract</p> <p>Background</p> <p>Pleistocene events have shaped the phylogeography of many taxa worldwide. Their genetic signatures in tropical species have been much less explored than in those living in temperate regions. We analysed the genetic structure of a Malagasy primate species, a mouse lemur with a wide distribution (<it>M. murinus)</it>, in order to investigate such phylogeographic processes on a large tropical island. We also evaluated the effects of anthropogenic pressures (fragmentation/deforestation) and natural features (geographic distance, rivers) on genetic structure in order to complement our understanding of past and present processes of genetic differentiation.</p> <p>Results</p> <p>The analysis of the mitochondrial D-loop sequences of 195 samples from 15 study sites (10 from a continuous forest and five from isolated forest fragments) from two adjacent Inter-River-Systems (IRSs) revealed that forest fragmentation and the river restrict gene flow, thereby leading to an increased genetic differentiation between populations beyond the effect of isolation-by-distance. Demographic simulations detected signals of two successive spatial expansions that could be preliminarily dated to the late Pleistocene and early Holocene. The haplotype network revealed geographic structure and showed deep molecular divergences within and between the IRSs that would be congruent with a two-step colonization scenario.</p> <p>Conclusions</p> <p>This study supports the hypothesis of a relatively recent spatial expansion of the grey mouse lemur in northwestern Madagascar, which may also explain why this taxon, in contrast to its congeners, has not yet undergone allopatric speciation in the studied area and possibly across its presently wide range.</p
AI GOVERNANCE: ARE CHIEF AI OFFICERS AND AI RISK OFFICERS NEEDED?
While AI provides many business opportunities across industries, the organizational implications of AI are still largely unclear. We investigate governance roles related to AI use in practice, and undertake first steps to define the role profiles of a Chief AI Officer (CAIO) and an AI Risk Officer (AIRO). We base our inquiry on two sources: a literature review and evaluative interviews with nine AI professionals from small- and medium-sized companies. We find that, whereas the roles and activities associated with the CAIO and AIRO are commonly deemed relevant for such companies in the long run, today only a few companies have implemented them. Especially the creation of the CAIO position seems justified, due to the complexity of AI and the need for extensive interaction and coordination related to AI governance
Demographic Change and the European Income Distribution. ESRI DISCUSSION PAPER SERIES IZA DP No. 11440, March 2018
This paper assesses the effect of key demographic changes (population ageing and
upskilling) that are expected by 2030 on the income distribution in the EU-27 and examines
the potential of tax-benefit systems to counterbalance negative developments. Theory
predicts that population ageing should increase income inequality, while the effect of
up-skilling is more ambiguous. Tax-benefit systems may stabilize these expected changes
though this is largely an empirical question given their typically complex nature. We use
a decomposition technique to isolate the effect of projected demographic change on
income inequality and poverty from the reaction of the labor market to this demographic
change through wage adjustments. Our results show that demographic change is likely to
lead to increasing inequality while related wage adjustments work mainly in the opposite
direction. Changes to projected relative poverty are minimal for most countries. With a few
exceptions, EU tax-benefit systems are able to absorb most of projected increase in market
income inequality
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