The influence of process parameters and starting composition on the carbothermal production of sialon

The-sialons (Si_6-z Al _z O _z N_8-z ) can be produced by carbothermal reduction of kaolin. The reaction mechanism of the sialon formation has been studied by several methods. Firstly, the composition of the reaction product is determined by XRD as function of the reaction time at 1400 and 1 500 C. The influence of additives, pellet size, nitrogen flow and clay type on the reaction is studied. Secondly, the carbon monoxide leaving the furnace is monitored. By studying the changes in carbon monoxide output as a function of the above-mentioned parameters a better understanding of the reaction mechanism has been obtained.     

Computergestützte Frühwarn- und Entscheidungssysteme

Zusammenfassung Die massive Bedrohung durch Nuklearwaffen, die den Supermächten die Möglichkeit zur Auslöschung allen Lebens auf der Erde geben, erfordert eine Entscheidungsfindung oftmals innerhalb weniger Minuten. Dies hat beide Seiten zum Aufbau von Frühwarn- und Entscheidungssystemen (FWES) veranlaßt, durch deren Einsatz ein atomarer Angriff noch innerhalb der Raketenflugzeit erkannt werden soll. In diesem FWES spielt die Verarbeitung und Weiterleitung von Informationen durch den Computer eine kriegsentscheidende Rolle: Die Informatik ist zu einer der wichtigsten Grundlagenwissenschaften in der Rüstungsforschung geworden. Dieser Artikel gibt eine Übersicht über die Funktionsweise computergestützter FWES und zeigt Fehlerquellen auf, die es möglich und sogar wahrscheinlich machen, daß eine Verkettung unglücklicher Umstände zu einem Nuklearkrieg aus Versehen führen kann.

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Liste der Abkürzungen ANMCC Alternate National Military Command Center - BMWES Ballistic Missile Early Warning System - CSS Communication System Segment - EMP Elektromagnetischer Puls - FWES Frühwarn- und Entscheidungssystem - ICBM Intercontinental Ballistic Missile - JCS Joint Chief of Staff - NCS NORAD Computer System - NMCC National Military Command Center - NORAD North American Aerospace Defense Command Center - PAC Pacific Command - PARCS Perimeter Acquisition Radar Attack Characterization System - SAC Strategic Air Command - SCC Space Computational Center - SLBM Submarine-launched Ballistic Missiles - WWMCCS World Wide Military Command and Control System     

Making fast cylindrical gradient-index lenses diffraction limited by using a wave-front-correction element

A wave-front-correction element (WFCE) is produced to make a cylindrical Ag-ion-exchanged gradient-index (GRIN) lens with a high numerical aperture (0.53) diffraction limited (wave-front error, 0.02lambda rms). The wave-front aberrations of the cylindrical GRIN lens are measured by a phase-shifting shearing interferometer, with a conventional microscope objective used as a compensation lens. The continuous surface relief of the WFCE is produced by a lithographic process. The wave-front-corrected GRIN lens is applied to collimate the strongly divergent light (57 degrees full diverging angle measured at 1/e(2) of maximum intensity) emitted by a high-power diode laser. The power irradiated into a full angle of 2 mrad can be enhanced by a factor of 1.8 with the WFCE.     

Nodes on ropes: a comprehensive data and control flow for steering ensemble simulations

Flood disasters are the most common natural risk and tremendous efforts are spent to improve their simulation and management. However, simulation-based investigation of actions that can be taken in case of flood emergencies is rarely done. This is in part due to the lack of a comprehensive framework which integrates and facilitates these efforts. In this paper, we tackle several problems which are related to steering a flood simulation. One issue is related to uncertainty. We need to account for uncertain knowledge about the environment, such as levee-breach locations. Furthermore, the steering process has to reveal how these uncertainties in the boundary conditions affect the confidence in the simulation outcome. Another important problem is that the simulation setup is often hidden in a black-box. We expose system internals and show that simulation steering can be comprehensible at the same time. This is important because the domain expert needs to be able to modify the simulation setup in order to include local knowledge and experience. In the proposed solution, users steer parameter studies through the World Lines interface to account for input uncertainties. The transport of steering information to the underlying data-flow components is handled by a novel meta-flow. The meta-flow is an extension to a standard data-flow network, comprising additional nodes and ropes to abstract parameter control. The meta-flow has a visual representation to inform the user about which control operations happen. Finally, we present the idea to use the data-flow diagram itself for visualizing steering information and simulation results. We discuss a case-study in collaboration with a domain expert who proposes different actions to protect a virtual city from imminent flooding. The key to choosing the best response strategy is the ability to compare different regions of the parameter space while retaining an understanding of what is happening inside the data-flow system.     

World lines

In this paper we present World Lines as a novel interactive visualization that provides complete control over multiple heterogeneous simulation runs. In many application areas, decisions can only be made by exploring alternative scenarios. The goal of the suggested approach is to support users in this decision making process. In this setting, the data domain is extended to a set of alternative worlds where only one outcome will actually happen. World Lines integrate simulation, visualization and computational steering into a single unified system that is capable of dealing with the extended solution space. World Lines represent simulation runs as causally connected tracks that share a common time axis. This setup enables users to interfere and add new information quickly. A World Line is introduced as a visual combination of user events and their effects in order to present a possible future. To quickly find the most attractive outcome, we suggest World Lines as the governing component in a system of multiple linked views and a simulation component. World Lines employ linking and brushing to enable comparative visual analysis of multiple simulations in linked views. Analysis results can be mapped to various visual variables that World Lines provide in order to highlight the most compelling solutions. To demonstrate this technique we present a flooding scenario and show the usefulness of the integrated approach to support informed decision making.     

AI and robotics in the European restaurant sector: Assessing potentials for process innovation in a high-contact service industry

Electronic Markets - The restaurant technology market is rapidly evolving and is transforming the restaurant business as a significant sector of tourism and hospitality. Enabled by artificial...     

Influence of nitrogen uptake and heat treatment on the microstructural characteristics and corrosion performance of X190CrVMo20-4-1 steel produced by supersolidus liquid-phase sintering

Martensitic stainless steel powder exhibits a high nitrogen uptake when densified by supersolidus liquid-phase sintering in a nitrogen atmosphere, but the optimum uptake, which is beneficial to its resistance to corrosion, is unknown. In this study, the resistance of high-carbon martensitic stainless steel X190CrVMo20-4-1 densified in a nitrogen atmosphere against pitting corrosion was explored. This was to clarify the impact of nitrogen uptake in the steel matrix in the quenched and tempered condition on its corrosion resistance in an aqueous solution. Samples were subjected to potentiodynamic polarisation tests in a de-aerated, 1 wt% NaCl solution. Results revealed that the X190 steel densified in a nitrogen atmosphere at 40-kPa pressure, subjected to deep cryogenic treatment in liquid nitrogen at an austenitising temperature of 1150°C and tempered at 200°C, had the best pitting corrosion resistance with a breakdown potential of 142 ± 11 mV/SCE and a hardness of 738 ± 4 HV10. The matrix around the M₇C₃ carbides and MX carbonitrides suffered high pitting susceptibility. The implications of this study serve as a basis for the improvement of the functional properties of steels.