Evaluation of the Test Temperature Effect on Failure Mechanisms and Notched Impact Strength Characteristics of Ultra-Hard Low Alloy Steels

На основании данных фрактографического анализа оценено изменение механизмов разрушения высокопрочных малолегированных сталей ARMOX 500T и ARMOX 600T в зависимости оттемпературы испытаний. В экспериментально исследованномтемпературном диапазоне -80...100°C была установлена высокая вероятность достижения предельного состояния этих материалов.На основі даних фрактографічного аналізу оцінено зміну механізмів руйнування високоміцних малолегованих сталейARMOX 500T та ARMOX 600T у залежності від температури випробувань. В експериментально дослідженому температурному інтервалі-80...100°C установлено високу імовірність досягнення граничного стану цих матеріалів

MODELLING OF COLLECTIVE MOVEMENT IN IMMERSIVE ENVIRONMENTS

Immersive technologies allow us to map physical reality by means of 4D virtual systems in ever higher spatial and temporal detail, up to a scale level of 1 : 1. This level of detail enables the representation of phenomena that have been widely ignored by the geovisualization research agenda as yet. An example for such a large scale phenomenon is the collective movement of animals, which can be modelled and visualized only at a fine grained spatio-temporal resolution. This paper focuses on how collective movement can be modelled in an immersive virtual reality (VR) geovisualization. In a brief introduction on immersion and spatial presence we will argue, that high fidelity and realistic VR can strengthen the users’ involvement with the issues visualized. We will then discuss basic characteristics of swarming in nature and review the principal models that have been presented to formalize this collective behavior. Based on the rules of (1) collision avoidance, (2) polarization, (3) aggregation and (4) self-organized criticality we will formulate a viable solution of modelling collective movement within a geovisualization immersive virtual environment. An example of use and results will be presented

Plasma Properties in the Plume of a Hall Thruster Cluster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76225/1/AIAA-3765-486.pd

Electron-wall interaction in Hall thrusters

Electron-wall interaction effects in Hall thrusters are studied through measurements of the plasma response to variations of the thruster channel width and the discharge voltage. The discharge voltage threshold is shown to separate two thruster regimes. Below this threshold, the electron energy gain is constant in the acceleration region and therefore, secondary electron emission (SEE) from the channel walls is insufficient to enhance electron energy losses at the channel walls. Above this voltage threshold, the maximum electron temperature saturates. This result seemingly agrees with predictions of the temperature saturation, which recent Hall thruster models explain as a transition to space-charge saturated regime of the near-wall sheath. However, in the experiment, the maximum saturation temperature exceeds by almost three times the critical value estimated under the assumption of a Maxwellian electron energy distribution function. The channel narrowing, which should also enhance electron-wall collisions, causes unexpectedly larger changes of the plasma potential distribution than does the increase of the electron temperature with the discharge voltage. An enhanced anomalous crossed-field mobility (near wall or Bohm-type) is suggested by a hydrodynamic model as an explanation to the reduced electric field measured inside a narrow channel. We found, however, no experimental evidence of a coupling between the maximum electron temperature and the location of the accelerating voltage drop, which might have been expected due to the SEE-induced near-wall conductivity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87763/2/057104_1.pd

Characterization of SNF 9007, A Novel Cholecystokinin/Opoid Ligand in Mouse Ileum in Vitro: Evidence for Involvement of CholecystokininA and CholecystokininB Receptors in Regulation of Ion Transport1

ABSTRACT The effects of cholecystokinin (CCK) fragments and Asp-Tyr-DPh Gly-Trp-[N-Me]Nle-Asp-Phe-NH

Block and gradient copoly(2-oxazoline) micelles : strikingly different on the inside

Herein, we provide a direct proof for differences in the micellar structure of amphiphilic diblock and gradient copolymers, thereby unambiguously demonstrating the influence of monomer distribution along the polymer chains on the micellization behavior. The internal structure of amphiphilic block and gradient co poly(2-oxazolines) based on the hydrophilic poly(2-methyl-2-oxazoline) (PMeOx) and the hydrophobic poly(2-phenyl-2-oxazoline) (PPhOx) was studied in water and water ethanol mixtures by small-angle X-ray scattering (SAXS), small angle neutron scattering (SANS), static and dynamic light scattering (SLS/DLS), and H-1 NMR spectroscopy. Contrast matching SANS experiments revealed that block copolymers form micelles with a uniform density profile of the core. In contrast to popular assumption, the outer part of the core of the gradient copolymer micelles has a distinctly higher density than the middle of the core. We attribute the latter finding to back-folding of chains resulting from hydrophilic hydrophobic interactions, leading to a new type of micelles that we refer to as micelles with a "bitterball-core" structure