1,923 research outputs found
A hypersonic research vehicle to develop scramjet engines
Four student design teams produced conceptual designs for a research vehicle to develop the supersonic combustion ramjet (scramjet) engines necessary for efficient hypersonic flight. This research aircraft would provide flight test data for prototype scramjets that is not available in groundbased test facilities. The design specifications call for a research aircraft to be launched from a carrier aircraft at 40,000 feet and a Mach number of 0.8. The aircraft must accelerate to Mach 6 while climbing to a 100,000 foot altitude and then ignite the experimental scramjet engines for acceleration to Mach 10. The research vehicle must then be recovered for another flight. The students responded with four different designs, two piloted waverider configurations, and two unmanned vehicles, one with a blended body-wing configuration, the other with a delta wing shape. All aircraft made use of an engine database provided by the General Electric Aircraft Engine Group; both turbofan ramjet and scramjet engine performance using liquid hydrogen fuel was available. Explained here are the students' conceptual designs and the aerodynamic and propulsion concepts that made their designs feasible
Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines
Single trajectories of magnetic line motion indicate the persistence of a
central protected plasma core, surrounded by a chaotic shell enclosed in a
double-sided transport barrier : the latter is identified as being composed of
two Cantori located on two successive "most-noble" numbers values of the
perturbed safety factor, and forming an internal transport barrier (ITB).
Magnetic lines which succeed to escape across this barrier begin to wander in a
wide chaotic sea extending up to a very robust barrier (as long as L<1) which
is identified mathematically as a robust KAM surface at the plasma edge. In
this case the motion is shown to be intermittent, with long stages of
pseudo-trapping in the chaotic shell, or of sticking around island remnants, as
expected for a continuous time random walk.Comment: TEX file, 84 pages including 32 color figures. Higher quality figures
can be seen on the PDF file at
http://membres.lycos.fr/fusionbfr/JHM/Tokamap/JSP.pd
Heterogeneous Causal Effects of Financial Incentives on Weight Loss – Results of a Large Prospective Randomized Trial
In a randomized controlled trial involving 700 obese persons assigned to three experimental groups, we test whether financial incentives have heterogeneous effects on weight reduction. While two treatment groups obtain EUR 150 and EUR 300, respectively, for achieving an individually-assigned target weight within four months, a control group receives no such premium. The objective is to identify subgroups of patients (male/female, natives/migrants, etc.) who respond more than others to financial incentives. Our conclusions are the following: (1) monetary rewards effectively induce obese individuals to reduce weight across all subgroups; (2) the magnitude of the reward is relevant only for certain subgroups; (3) for people who do not lose weight via conventional weight-loss intervention programs, financial incentives are an effective supplement to induce weight loss.Im Rahmen eines randomisierten Experiments mit 700 adipösen Studienteilnehmern und drei Experimentalgruppen wird untersucht, ob die Effektivität von finanziellen Anreizen zur Gewichtsreduktion von bestimmten individuellen Merkmalen abhängt. Während zwei Gruppen bis zu 150 Euro und 300 Euro für das Erreichen eines individuellen Zielgewichts versprochen wurde, war eine Kontrollgruppe keinem finanziellen Anreiz ausgesetzt. Zentrales Studienziel ist die Identifizierung von Patientensubgruppen (Männer/Frauen, Migranten/Nicht-Migranten, etc.), die stärker auf finanzielle Anreize wirken als andere. Unsere Analyse kommt zu folgendem Ergebnis: (1) finanzielle Anreize regen alle betrachtete Subgruppen zur Gewichtsreduktion an, (2) die Höhe der Prämie ist nur für bestimmte Subgruppen relevant und (3) Geldprämien stellen eine effektive Ergänzung zu Standardbehandlungsprogrammen auch bei denjenigen Adipösen dar, die alleine auf Basis der Standardbehandlung keine nennenswerte Abnehmerfolge erzielen können
Pressure Dependence of the Elastic Moduli in Aluminum Rich Al-Li Compounds
I have carried out numerical first principles calculations of the pressure
dependence of the elastic moduli for several ordered structures in the
Aluminum-Lithium system, specifically FCC Al, FCC and BCC Li, L1_2 Al_3Li, and
an ordered FCC Al_7Li supercell. The calculations were performed using the full
potential linear augmented plane wave method (LAPW) to calculate the total
energy as a function of strain, after which the data was fit to a polynomial
function of the strain to determine the modulus. A procedure for estimating the
errors in this process is also given. The predicted equilibrium lattice
parameters are slightly smaller than found experimentally, consistent with
other LDA calculations. The computed elastic moduli are within approximately
10% of the experimentally measured moduli, provided the calculations are
carried out at the experimental lattice constant. The LDA equilibrium shear
modulus C11-C12 increases from 59.3 GPa in Al, to 76.0 GPa in Al_7Li, to 106.2
GPa in Al_3Li. The modulus C_44 increases from 38.4 GPa in Al to 46.1 GPa in
Al_7Li, then falls to 40.7 GPa in Al_3Li. All of the calculated elastic moduli
increase with pressure with the exception of BCC Li, which becomes elastically
unstable at about 2 GPa, where C_11-C_12 vanishes.Comment: 17 pages (REVTEX) + 7 postscript figure
Adaptation of an Evaluation System for e-Health Environments
Proceedings of: 14th International Conference, KES 2010, Cardiff, UK, September 8-10, 2010The increase in ageing of European population implies a high cost in economy and society in any European country and it can be reduced if we pay attention and develop home care systems. Evaluation of these systems is a critical and challenging issue but seldom tackled. It is important before evaluating a system to figure out what is the evaluation goal. In our case, such a goal is to evaluate enhanced user experience and beyond the evaluation goal it is also a central concern about what to evaluate. In this paper we propose a multi-agent home care system where we describe how agents coordinate their decisions to provide e-services to patients when at home after hospitalization. Finally we center our proposal on the adaptation of an evaluation system, previously developed, to support the challenges of an e-Health environment and also the multi-user evaluation. These evaluation methods (online/offline) will provide user's (patients, patient's relatives and healthcare professionals) feedback into the system.This work was supported in part by Projects CICYT TIN2008-06742-C02-02/
TSI, CICYT TEC2008-06732-C02-02/TEC, CAM CONTEXTS (S2009/
TIC-1485) and DPS2008-07029-C02-02.Publicad
Moisture Induced Damages to Building Foundations
The effect of moisture on foundation soils is a very important factor in the design of building foundations especially when the foundation soils are expansive in nature. The variations in subgrade moisture, with corresponding change in volume and strength characteristics of foundation soils may cause severe damage to the building. Two case histories are described where excess moisture in foundation soils caused damages to the building in distinctly different ways. In one case, moisture increase in the expansive foundation soils caused considerable swelling of the clays resulting in severe damage to the building. In the other case, excess moisture caused wash out of filter material causing considerable settlement of a sidewalk adjacent to a building. In both cases, excess moisture was related to a break in the underground water lines
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DNA methylation-based classification of central nervous system tumours.
Accurate pathological diagnosis is crucial for optimal management of patients with cancer. For the approximately 100 known tumour types of the central nervous system, standardization of the diagnostic process has been shown to be particularly challenging-with substantial inter-observer variability in the histopathological diagnosis of many tumour types. Here we present a comprehensive approach for the DNA methylation-based classification of central nervous system tumours across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that the availability of this method may have a substantial impact on diagnostic precision compared to standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility, we have designed a free online classifier tool, the use of which does not require any additional onsite data processing. Our results provide a blueprint for the generation of machine-learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology
Effect of a zero g environment on flammability limits as determined using a standard flammability tube apparatus
Flammability limits in a zero gravity environment were defined. Key aspects of a possible spacelab experiment were investigated analytically, experimentally on the bench, and in drop tower facilities. A conceptual design for a spacelab experiment was developed
Chemical Ecology of Nematodes
Nematodes represent the most abundant group of metazoans on earth. They utilize diverse chemicals to interact with con-specific and hetero-specific organisms, and are also impacted by compounds produced by other interacting organisms. In the first part of this review we discuss how nematode-derived glycolipids modulate their behavior and development, as well as the interactions with other organisms. Furthermore, we provide a short overview about other secondary metabolites produced by nematodes that affect different life traits of free-living nematodes. In the second part of this review we discuss how different bacteria-, nematode-, and plant-derived chemicals such as volatile organic compounds, root exudates, and plant defenses regulate the interaction between entomopathogenic nematodes, their symbiotic bacteria, insect prey, predators, and plants
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