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

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

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

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

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

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

Experimental Metrics for Identifying Origins of Combustion Variability during Spark-Assisted Compression Ignition

Spark-assisted compression ignition, SACI, can be used to control the combustion phasing of compression-ignition gasoline engines. However, implementation of this technique can be confounded by cyclic variability. The purpose of this paper is to define experimental metrics that describe the SACI process and to demonstrate the use of these metrics for identifying the source(s) of cyclic variability during the SACI process. This study focused on a light load condition (7 mg/cycle, 200 kPa i.m.e.p.), where spray-guided direct fuel injection with spark ignition and an exhaust-rebreathing strategy was employed to achieve flame propagation, which led to compression ignition. This study employed a combination of measurements including pressure-based heat-release analysis, spark-discharge voltage/current measurements, and cycle-resolved combustion imaging. Based on these measurements, four distinct combustion periods were identified; namely, the spark discharge, the early kernel growth (EKG), flame propagation, and the compression ignition periods. Metrics were defined to characterize each period and used to identify the contribution of each period to the cyclic variability of the main heat release. For the light load condition studied here, the EKG period had the largest effect on the crank angle (CA) position of 50 per cent mass burned, CA50. The spark-discharge event may affect CA50 indirectly through its influence on EKG. However, this could not be definitively assessed here since the camera was incapable of recording both the spark-discharge event and the flame images during cycles of the same tests.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86770/1/Sick18.pd

A novel, non-invasive, online-monitoring, versatile and easy plant-based probe for measuring leaf water status

A high-precision pressure probe is described which allows non-invasive online-monitoring of the water relations of intact leaves. Real-time recording of the leaf water status occurred by data transfer to an Internet server. The leaf patch clamp pressure probe measures the attenuated pressure, Pp, of a leaf patch in response to a constant clamp pressure, Pclamp. Pp is sensed by a miniaturized silicone pressure sensor integrated into the device. The magnitude of Pp is dictated by the transfer function of the leaf, Tf, which is a function of leaf patch volume and ultimately of cell turgor pressure, Pc, as shown theoretically. The power function Tf=f(Pc) theoretically derived was experimentally confirmed by concomitant Pp and Pc measurements on intact leaflets of the liana Tetrastigma voinierianum under greenhouse conditions. Simultaneous Pp recordings on leaflets up to 10 m height above ground demonstrated that changes in Tf induced by Pc changes due to changes of microclimate and/or of the irrigation regime were sensitively reflected in corresponding changes of Pp. Analysis of the data show that transpirational water loss during the morning hours was associated with a transient rise in turgor pressure gradients within the leaflets. Subsequent recovery of turgescence during the afternoon was much faster than the preceding transpiration-induced water loss if the plants were well irrigated. Our data show the enormous potential of the leaf patch clamp pressure probe for leaf water studies including unravelling of the hydraulic communication between neighbouring leaves and over long distances within tall plants (trees)