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Design and simulation of gas burner ejectors

Carbon Resources Conversion 2021年第1期4卷 28-35页

作者： Mario Pichler Florian Wesenauer Christian Jordan Stefan Puskas Bernhard Streibl franz winter Michael Harasek Institute of Chemical Environmental&Bioscience EngineeringTU WienGetreidemarkt 9/1661060 ViennaAustria Wienerberger AG Wienerbergerplatz 11100 ViennaAustria DrS3–Strömungsberechnung und Simulation e.U. Simmeringer Hauptstraße 397/1411110 ViennaAustria

Ignition within gas burner ejectors can lead to off design conditions and has significant influence on the burner *** ignition in the ejector should be *** the present study the influence of combustion reactions on the performance of gas burner injectors is *** investigate if ignition is possible,simulated ignition delay times,using a detailed reaction mechanism,are compared to predicted mean residence times of the gas in the *** burner ejectors are designed using one dimensional analytic equations,based on energy and momentum conservation equations and conventional isentropic equations.1D results are compared to 2D computational fluid dynamics(CFD)simulations,to take into account non-ideal mixing effects along the *** are validated with experiments with air at room temperature.1D results show very good agreement not only with CFD simulations for the case of non-reactive flows,but also with performed *** is shown that the assumption of ideal mixing along the ejector and thus the comparison of the ignition delay time to the gas mean residence time,to predict ignition in the ejector,is not *** in the ejector is possible,even if the ignition delay time is more than thirty times higher than the mean residence *** addition to that,it is shown,that ignition and the choice of reaction mechanism have significant influence on the predicted gas burner ejector ***,the accurate prediction of ignition delay time and the use of a detailed reaction kinetic are mandatory to correctly predict the burner ejector behavior.

关键词： Self-ignition Flammability limits Reacting jet Ejector Jet pump Computational fluid dynamics

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The Algebro-Geometric Method for Solving Algebraic Differential Equations——A Survey

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Journal of Systems Science & Complexity 2019年第1期32卷 256-270页

作者： WINKLER franz Research Institute for Symbolic Computation J.Kepler University

This paper presents the algebro-geometric method for computing explicit formula solutions for algebraic differential equations(ADEs). An algebraic differential equation is a polynomial relation between a function, some of its partial derivatives, and the variables in which the function is de?*** all these quantities as unrelated variables, the polynomial relation leads to an algebraic relation de?ning a hypersurface on which the solution is to be found. A solution in a certain class of functions, such as rational or algebraic functions, determines a parametrization of the hypersurface in this class. So in the algebro-geometric method the author ?rst decides whether a given ADE can be parametrized with functions from a given class; and in the second step the author tries to transform a parametrization into one respecting also the differential conditions. This approach is relatively well understood for rational and algebraic solutions of single algebraic ordinary differential equations(AODEs). First steps are taken in a generalization to systems and to partial differential equations.

关键词： Algebraic differential equation exact solution parametrization of curves

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Carbon Footprint of Transitional Shelters

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International Journal of Disaster Risk Science 2015年第3期6卷 226-237页

作者： Matti Kuittinen Stefan winter Department of Architecture School of Arts Design and Architecture Aalto University Faculty of Civil Geo and Environmental EngineeringTechnische Universitt München

Extreme weather events, sea level rise, and political disputes linked to climate change are driving masses to leave their homes. Their transitional settlements should be produced in a manner that causes minimum greenhouse gas(GHG) emissions to prevent any further acceleration of climate change and the humanitarian crises it causes. This article presents a study of the carbon footprint and primary energy demand of the construction materials of eight different transitional shelters. The lowest carbon footprints were found from shelter models made from bamboo or timber. The highest emissions were caused by shelters that have either a short service life or that are made from metal-intensive structures. The choice of cladding materials was surprisingly important. The findings were further compared to the overall impacts of each construction project, to national per capita GHG emissions,and to construction costs. Some shelter projects had notable total energy consumption even compared to the annual energy use of industrialized countries. The study concludes that construction materials have an important impact on the carbon footprint of shelters. Comparisons should however be made only between similar functional units. Furthermore, benchmark values and more background data are urgently needed in order to give humanitarian nongovernmental organizations tools for lowering the carbon footprint of their construction operations.

关键词： Carbon footprint Humanitarian construction Lifecycle assessment Primary energy

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Fundamentals of Design and Technology of Rolling Element Bearings

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Chinese Journal of Aeronautics 2010年第1期23卷 123-136页

作者： franz-Josef Ebert FAG Aerospace GmbH & Co.KG D-97421 SchweinfurtGermany

This article presents an overview of fundamentals of rolling element bearing designs and technologies. The aim is to outline the complex interrelation of all fundamentals with the rolling contact fatigue and the attainable bearing life. Such fundamentals include, amongst others, bearing stressing and life capability. The article shows the different types of rolling bearing stressing and the analysis of the stress distribution （principal stresses and equivalent stresses） in the material under the rolling contact area. It becomes obvious that the contamination of the bearing with foreign particles leads to a drastic reduction in bearing life. Furthermore, it demonstrates the impact of the bearing lubrication and coating as well as the effect of additives on the attainable life and wear. Further fundamentals of rolling element bearing de- sign are the materials, the material cleanliness and the heat treatment. The article reveals the importance of the clean- liness of bearing steels as well as different types of inclusions and their effect on rolling contact fatigue. Additionally the article describes how to optimize the material properties （strength, toughness and residual stress） by the heat treat- nlent processes. The outcome of these investigations is that endurance life of a rolling element bearing can be achieved if specific operating conditions, an adequate lubrication, good system cleanliness and specific bearing stressing are met. The article provides a guideline for bearing engineers on how designs and technologies can be applied to optimizing a bearing for a particular industry or aerospace application.

关键词： aerospace rolling contact fatigue endurance life materials heat treatment lubrication reliability

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Saturated Hydraulic Conductivity from Field Measurements Compared to Pedotransfer Functions in a Heterogeneous Arable Landscape

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Journal of Earth Science 2010年第6期21卷 923-930页

作者： Florian winter Markus Disse Institute of Hydro Sciences Universitt der Bundeswehr München

A high degree of uncertainty with regard to soil parameterisation limits the significance of physically-based simulation of distributed flood control measures, which affect the runoff generation process, such as land-use changes or differing soil tillage practices. In this study, the soil measurement data from the hillslope scale at the Scheyern research farm were compared to demonstrate this uncertainty. To account for the spatial variability of soils in the investigation area of Scheyern, different approaches were applied to estimate soil hydraulic properties and saturated hydraulic conductivity, and were compared to field measurements

关键词： hydraulic conductivity pedotransfer function hood infiltrometer uncertainty distributed flood control measures.

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An Overview of Performance Characteristics, Experiencesand Trends of Aerospace Engine Bearings Technologies

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Chinese Journal of Aeronautics 2007年第4期20卷 378-384页

作者： Ebert franz-Josef Sales and Product Development Aerospace FAG Aerospace GmbH & Co. KG Schweinfurt D-97421 Germany

In this paper, the operating conditions, technical requirements, performance characteristics, design ideas, application experiences and development trends of aerospace engine bearings, including material technology, integration design and reliability, are reviewed. The development history of aerospace engine bearing is recalled briefly at first. Then today＇s material technologies and the high bearing performances of the bearings obtained through the new materials are introduced, which play important roils in the aeroengine bearing developments. The integration design ideas and practices are explained to indicate its significant advantages and importance to the aerospace engine bearings. And the reliability of the shaft-bearing system is pointed out and treated as the key requirement with goals for both engine and bearing. Finally, as it is believed that the correct design comes from practice, the pre-qualification rig testing conducted by FAG Aerospace GmbH ＆ Co. KG is briefly illustrated as an example. All these lead to the development trends of aerospace engine bearings from different aspects.

关键词： aerospace engine bearing performance characteristic material technology integrated bearing design reliability system cost

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Deep learning for geometric and semantic tasks in photogrammetry and remote sensing

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Geo-Spatial Information Science 2020年第1期23卷 10-19页

作者： Christian Heipke franz Rottensteiner Institute of Photogrammetry and GeoInformation(PI) Leibniz University HannoverHannoverGermany

During the last few years,artificial intelligence based on deep learning,and particularly based on convolutional neural networks,has acted as a game changer in just about all tasks related to photogrammetry and remote *** have shown partly significant improvements in many projects all across the photogrammetric processing chain from image orientation to surface reconstruction,scene classification as well as change detection,object extraction and object tracking and recognition in image *** paper summarizes the foundations of deep learning for photogrammetry and remote sensing before illustrating,by way of example,different projects being carried out at the Institute of Photogrammetry and GeoInformation,Leibniz University Hannover,in this exciting and fast moving field of research and development.

关键词： Deep learning machine learning convolutional neural networks(CNN) example project from IPI

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A spatial framework for detecting anthropogenic impacts on predator-prey interactions that sustain ecological integrity in Mexico

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Ecological Processes 2018年第1期7卷 408-424页

作者： franz Mora Coordinación del Sistema de Información Espacial para el Soporte de Decisiones sobre Impactos a la Biodiversidad.Comisión Nacional para el Conocimiento y Uso de la Biodiversidad(CONABIO) Liga Periférico-Insurgentes SurNúm.4903Col.Parques del Pedregal14010 Delegación TlalpanMexico

Background:This paper presents several spatial indicators developed to evaluate anthropogenic impacts on predator-prey interactions and their relationship with ecological integrity loss in *** integrity loss is defined as the inability to sustain viable populations,habitat functions,and species interactions of Nearctic and Neotropical apex predators as a result of anthropogenic *** direct impacts,the indicators evaluate habitat loss and the number of inhospitable *** indirect impacts,the indicators evaluate the avoidance of human features such as highways,roads,and human *** total impact level is described at 1 km^(2) resolution,and registered within the domain defined by the spatial habitat requirements of apex *** impact level is associated with ecological integrity loss,or the ecosystem capacity to reorganize habitat functions and sustain predator-prey interactions as the most visible elements of ecological *** integrity loss is evaluated for different groups of apex predators that are classified with different levels of anthropogenic ***:The framework presented here identifies the spatial information needed for the assessment of cumulative anthropogenic *** characterizing their distribution range,Nearctic predators have significantly larger intact habitats than neotropical predators but with higher ecological degradation,less landscape transformation,and overall less ecological *** observed within their distribution areas,indirect impacts have a generalized effect in the broad range of landscapes in *** integrity loss is the result of road,highway,and human settlement avoidance;but landscape transformation and human activity control the threshold for which ecological integrity loss becomes *** the other hand,there are no significant differences in impact levels among threat conservation categories for apex predators,which indicate that all predator

关键词： Anthropogenic impacts Ecological integrity Spatial indicators Apex predators Impact assessment

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Pesticide food safety standards as companions to tolerances and maximum residue limits

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Journal of Integrative Agriculture 2015年第11期14卷 2358-2364页

作者： Carl K winter Elizabeth A Jara Department of Food Science and Technology University of California

Allowable levels for pesticide residues in foods, known as tolerances in the US and as maximum residue limits （MRLs） in much of the world, are widely yet inappropriately perceived as levels of safety concern. A novel approach to develop scientifically defensible levels of safety concern is presented and an example to determine acute and chronic pesticide food safety standard （PFSS） levels for the fungicide captan on strawberries is provided. Using this approach, the chronic PFSS level for captan on strawberries was determined to be 2 000 mg kg-1 and the acute PFSS level was determined to be 250 mg kg-1. Both levels are far above the existing tolerance and MRLs that commonly range from 3 to 20 mg kg-~, and provide evidence that captan residues detected at levels greater than the tolerance or MRLs are not of acute or chronic health concern even though they represent violative residues. The benefits of developing the PFSS approach to serve as a companion to existing tolerances/MRLs include a greater understanding concerning the health significance, if any, from exposure to violative pesticide residues. In addition, the PFSS approach can be universally applied to all potential pesticide residues on all food commodities, can be modified by specific jurisdictions to take into account differences in food consumption practices, and can help prioritize food residue monitoring by identifying the pesticide/commodity combinations of the greatest potential food safety concern and guiding development of field level analytical methods to detect pesticide residues on prioritized pesticide/commodity combinations.

关键词： pesticide residues food safety tolerances maximum residue limits (MRLs) regulation reference dose captan strawberries

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Checking Content Consistency of Integrated Web Documents

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Journal of Computer Science & Technology 2006年第3期21卷 418-429页

作者： franz Weitl Burkhard Freitag Department of Mathematics and Computer Science University of Passau D-94030 Passau Germany

A conceptual framework for the specification and verification of constraints on the content and narrative structure of documents is proposed. As a specification formalism, CTLDL is defined, which is an extension of the temporal logic CTL by description logic concepts. In contrast to existing solutions this approach allows for the integration of ontologies to achieve interoperability and abstraction from implementation aspects of documents. This makes CTLDL specifically suitable for the integration of heterogeneous and distributed information resources in the semantic web.

关键词： document verification content consistency model checking temporal description logics CTL DL

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