548 research outputs found
Herbicides for commercial truck crops, 1971
"MP 221, 2/71/1M""Herbicides are a valuable "tool" for the vegetable producer in his constant battle against weeds. Weeds not only compete with vegetables for light, moisture and nutrients, but also may harbor insects and diseases. In many situations herbicides are the most economical means of controlling weeds. In some situations herbicides may be the only practical means of controlling weeds. However, other methods of weed control (cultivation, mulching) may prove economical or practical in still other situations."--Page 1.By A.E. Gaus and D.D. Hemphill (Department of Horticulture
Herbicides for commercial fruit crops, 1971
"MP 220, 2/71/2M""Herbicides are a valuable 'tool' for the fruit grower in his constant battle against weeds. Weeds not only compete with fruit crops for light, moisture and nutrients, but also may harbor insects and diseases and often interfere with other operational practices. In many situations herbicides are the most economical means of controlling weeds. In some situations herbicides may be the only practical means of controlling weeds. However, other methods of weed control (cultivation, mulching) may prove economical or practical in still other situations."--Page 1.By A.E. Gaus and D.D. Hemphill (Department of Horticulture
Differential Double-Excitation Cross Sections in 50-150-keV Proton-Helium Collisions
We have measured projectile-energy-loss spectra for 50-, 100-, and 150-keV p+He collisions. From the data we obtained differential double-excitation cross sections as a function of projectile scattering angle. At 150 keV a pronounced peak structure was observed at about 0.7 mrad for double excitation to the (2p2) 1D and (2s2p) 1P states. Our data provide indications for the dominance of a first-order mechanism involving the electron-electron interaction in double excitation for 150 keV at small scattering angles. At lower projectile energies and larger scattering angles a second-order mechanism appears to be of the same order of magnitude as the first-order mechanism. In these regimes, interference effects between the first- and second-order mechanisms could be important
Differential Double Excitation Cross Sections in Proton-Helium Collisions Studied by Energy-Loss Spectroscopy
We have measured ion energy-loss spectra for 150 keV proton-helium collisions as a function of the projectile scattering angle. From the data we obtained double excitation cross sections differential in the proton scattering angle as well as the ratios of both double excitation and single ionization to single excitation. In these ratios pronounced peak structures are observed at about 0.7 mrad. Two alternative interpretations of these peak structures are offered: They may be due to binary collisions between the projectile and the target electrons, or they could be a manifestation of an interference between different transition amplitudes leading to the same final state of the collision
Modus Vivendi Beyond the Social Contract: Peace, Justice, and Survival in Realist Political Theory
This essay examines the promise of the notion of modus vivendi for realist political theory. I interpret recent theories of modus vivendi as affirming the priority of peace over justice, and explore several ways of making sense of this idea. I proceed to identify two key problems for modus vivendi theory, so conceived. Normatively speaking, it remains unclear how this approach can sustain a realist critique of Rawlsian theorizing about justice while avoiding a Hobbesian endorsement of absolutism. And conceptually, the theory remains wedded to a key feature of social contract theory: political order is conceived as based on agreement. This construes the horizontal tensions among individual or group agents in society as prior to the vertical, authoritative relations between authorities and their subjects. Political authority thereby appears from the start as a solution to societal conflict, rather than a problem in itself. I argue that this way of framing the issue abstracts from political experience. Instead I attempt to rethink the notion of modus vivendi from within the lived experience of political conflict, as oriented not primarily toward peace, but political survival. With this shift of perspective, the idea of modus vivendi shows us, pace Bernard Williams, that the “first political question” is not how to achieve order and stability, but rather: what can I live with
Observation of Postcollision Effects in the Scattered Projectile Spectra for Ionizing Proton-Helium Collisions
We have measured and calculated doubly differential single ionization cross sections as a function of the scattering angle and the projectile energy loss for 50 to 150 keV proton-helium collisions. These cross sections show unexpected structures as a function of both the energy loss and the scattering angle, which are interpreted as due to the postcollision interaction. Although the effects of postcollision interactions have previously been observed in electron spectra, this is the first observation of such effects for the scattered protons
Differential Transfer Ionization Cross Sections for 50175-keV Proton-Helium Collisions
We have measured coincidences between neutralized projectiles and He recoil ions for 50175-keV proton-helium collisions. From the data we obtained transfer ionization (TI) cross sections differential in the projectile scattering angle. Laboratory scattering angles range from 0 to 2.0 mrad. The experimental method allowed separation of the postcollision charge states of the target atoms. The ratio of the cross sections for TI to the sum of TI and single capture, F, is presented as a function of projectile scattering angle. Comparison is made to previous measurements of this ratio where data is available. The differential cross sections are compared to dynamical classical trajectory Monte Carlo (dCTMC) calculations. Agreement in the shape of the differential cross sections is good between the theory and measurement over the entire energy range
The LIVE-L1 and LIVE-L3 experiments on melt behaviour in RPV lower head
Die Experimente LIVE-L1 und LIVE-L3 zum Schmelzenverhalten im unteren Plenum des RDB
Der Ablauf eines hypothetischen Kernschmelzunfalls in einem Reaktordruckbehälter (RDB) eines Druckwasserreaktors (DWR) beinhaltet eine große Anzahl komplexer physikalischer und chemischer Phänomene. Um das Verständnis über mögliche Ablaufszenarien von Kernschmelzunfällen bezüglich Kernzerstörung zu verbessern, wurde im September 2002 das LACOMERA Projekt am Forschungszentrum Karlsruhe gestartet. Das Ziel des Projektes war die Untersuchung von komplexen Prozessen während der Schmelzenseebildung und Verlagerung im RDB, Schmelzenausbreitung in die Reaktorgrube und Kernschmelze-Betonwechselwirkung und -Kühlung. Das LACOMERA Projekt mit einer Laufzeit von 4 Jahren war Bestandteil des 5. Rahmenprogramms der EU und eröffnete Forschungseinrichtungen der EU Mitgliedsländer und deren angegliederten Staaten den Zugang zu vier Großversuchsanlagen QUENCH, LIVE, DISCO und COMET am Forschungszentrum Karlsruhe.
Innerhalb des LIVE Versuchsprogramms wurden zwei Versuche (LIVE-L1 und LIVE-L2) des LACOMERA Projekts durchgeführt. Das Experiment LIVE-L1 ist Bestandteil dieses Berichts und wurde in Kooperation mit der Technischen Universität Sofia, Bulgarien und dem Kernkraftwerk Kozloduy NPP, Bulgarien geplant und durchgeführt.
Das Hauptziel des LIVE Programms ist es, das Verhalten der Kernschmelze während der späten Phase der Kernzerstörung und –Verlagerung im RDB sowohl experimentell in großem 3-dimensionalen Maßstab und in begleitenden Einzeleffektuntersuchungen als auch analytisch mit CFD Codes zu untersuchen. Dadurch soll eine bessere Einschätzung der Bandbreite der verbleibenden Unsicherheiten unter dem Aspekt der Sicherheitsbewertung ermöglicht werden.
Die Experimente LIVE-L1 und LIVE-L3 untersuchen das Verhalten eines Schmelzensees und einer Schmelzenkruste mit Luftzirkulation an der äußeren Behälterwand des RDB mit nachfolgender Außenflutung des unteren Plenums. Die Anfangs- und Randbedingungen in beiden Versuchen waren bis auf die Eingussposition der Schmelze in den Versuchsbehälter fast identisch. In LIVE-L1 wurde die Schmelze zentral und in LIVE-L3 am Rand in den Versuchsbehälter eingegossen. Die aus den Experimenten gewonnenen Informationen beinhal-ten Wärmestromverteilungen durch die Wand des RDB in transienten und stationären Versuchsphasen, Krustenwachstumsgeschwindigkeit und die Abhängigkeit der Krustenbildung von der Wärmestromverteilung. Detaillierte Nachuntersuchungen tragen außerdem zur Charakterisierung von Erstarrungsprozessen von nicht-eutektischen Schmelzen bei.
Die experimentellen Ergebnisse sollen weiterhin zur Entwicklung von mechanistischen Modellen verwendet werden, die das Schmelzenseeverhalten im Kern beschreiben sollen und dann in Systemcodes zur Analyse von schweren Störfällen wie z.B. ASTEC implementiert werden sollen.
Der vorliegende Bericht fasst die Ziele des LIVE Versuchsprogramms zusammen und präsentiert die wichtigen Ergebnisse der Experimente LIVE-L1 und LIVE-L3
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