32 research outputs found
Krakau / Geripp: Offiz. J. Krainz ; Terrain: Offcl. Ferd. Simon
No full textKRAKAU / GERIPP: OFFIZ. J. KRAINZ ; TERRAIN: OFFCL. FERD. SIMON
General-Karte von Mittel-Europa (-)
Krakau / Geripp: Offiz. J. Krainz ; Terrain: Offcl. Ferd. Simon (38°50°) ( -
Nowogeorgiewsk / Geripp: C. Lorenz ; Terrain: Offic. Ferd. Simon
No full textNOWOGEORGIEWSK / GERIPP: C. LORENZ ; TERRAIN: OFFIC. FERD. SIMON
General-Karte von Mittel-Europa (-)
Nowogeorgiewsk / Geripp: C. Lorenz ; Terrain: Offic. Ferd. Simon (38°52°) ( -
Behavioral modeling of GaN-based power amplifiers: impact of electrothermal feedback on the model accuracy and identification
Get PDFIn this article, we discuss the accuracy of behavioral models in simulating the intermodulation distortion (IMD) of microwave GaN-based high-power amplifiers in the presence of strong electrothermal (ET) feedback. Exploiting an accurate self-consistent ET model derived from measurements and thermal finite-element method simulations, we show that behavioral models are able to yield accurate results, provided that the model identification is carried out with signals with wide bandwidth and large dynamics
Birmingham News sleeve BN0023894
No full textJewish Community Center track dedication / Norman Niren, Howard Simon, Ferd Weil, Meyer Newfield, Abe Kaplan, David Staff, Morris Fisher / Get picture of Mayor Newfield and [--] Volker dedicating running track at Jewish Community Center / [Work order included
Model-based testing of simulation models: A case-study approach to test model design for automated testing of discrete-event simulation models
No full textModel-based testing (MBT) is applied for the verification of simple simulation models used in modeling & simulation for decision-making. It is found that MBT of simulation models is not discussed much in literature, and that existing case studies on this topic do not give guidelines for test model design. It is established that testing simulation models is a difficult problem, as simulation models have many states, a time component, reactiveness, and inherent stochasticity. It is hypothesized that MBT could lead to more efficient and effective testing, and could fit within a modular approach to verification of simulation models. A focus is made on verification that discrete-event simulation models meet their functional requirements, by using automated test packages.Options for test model design are explored in three case studies where automated test suites are developed for three simple simulation models that form the systems under test (SUT). Options from existing taxonomies are first selected for this, based on their relevance to the properties of simulation models that make dynamic verification difficult. In the process, an existing MBT software tool is selected and evaluated.The main aspects of MBT that are explored are: nondeterministic test models and SUTs, transition-based test models, online and reactive test execution, specification of oracles at different levels, time advancement of the SUT, the distinction between black-box and white-box approaches, and the problem of test abstraction. Examples are made where the test model, an extended finite state machine (EFSM), is an abstract version of the SUT, that includes its most relevant state transitions. An approach to testing is used, where the test model follows the SUT’s state and selects relevant assertions accordingly. This approach limits the use of stochasticity in the test model, that is often done in MBT. It is found that MBT can be useful for three types of dynamic verification: of the dynamic behavior, of the (end) results, and of the response to inputs. The first type is explored with a step-by-step approach where oracles are checked after each time advancement in the SUT. The second type is implemented without the use of MBT techniques, by extending the functionality of an existing MBT tool to allow for analysis of multiple simulation runs. The third type is not explored but approaches for it are defined.The project shows the feasibility of MBT of simulation models and shows different options for test model design. Not discussed are the adequacy of the developed test packages in detecting faults, and the efficiency, effectiveness and quality of MBT for simulation models in general.Engineering and Policy Analysi
Dynamic simulation of pantograph catenary interaction by means of finite elements and a reduced order model
No full textAs train speeds continue to increase, the dynamics of the interface between train and infrastructure is an increasingly important factor in current collection performance. European legislation prescribes that assessment of the quality of the current collection system shall be performed according to measurements and/or simulations. Due to the increase in computer power in recent years, simulations have become increasingly attractive as an addition or replacement to real line measurements. The goal of this work is to judge current collection quality through dynamic time-history simulations of the pantograph-catenary interface. First, the current state-of-art is reviewed, subsequently a simulation approach is determined, applied and tested to the norm EN50318:2002. Based on simulation results and comparison to measured values, the simulation approach is validated according to the norm EN50318:2002. As a consequence of the large finite element models used in the valid model, a method for enhancing the simulation speed without losing non-linearities is determined. Changes in solver and contact model are identified as possible improvements, as is a modal reduction of the model. In order to apply the proposed solver improvements, a test model is built in Matlab. The valid Ansys model is used to test simulation times as different contact models are used. A modal reduction approach is implemented in Matlab. It is found that as a consequence of solver changes, simulation times may improve by up to 40%. Furthermore, contact model changes may result in improvements of up to 77%. Modal reduction, when applied to the current model, has been found inefficient due to high amounts of interface DOF with respect to the full size of the model. Therefore, no results are presented for the modally reduced system. Non-optimized simulations currently require around 24 hours of simulation time. It is to be expected that multiple simulations need to be executed in order to simulate all possible pantograph combinations, thus performing all simulations may require days to weeks. This situation is deemed undesirable. Based on the findings in this work, it is concluded that simulation times may improve by a ratio [6:43] if solver and contact model are chosen wisely. Therewith simulation times per simulation may be reduced to 3.4 hours.Mechanical Engineering | Vehicle Engineerin
Geographic travels in central Australia from 1872 to 1874,
No full text"Plants collected by Mr. Giles ... Examined by Baron Ferd. Von Mueller": p. [209]-223.Mode of access: Internet
Le iardin d'armoiries contenant les armes de plusieurs nobles royaumes & maisons de Germanie inferieure: oeuure autant nouueau, que proufitable à tous amateurs du noble exercice d'armes = Den boomgaert der wapenen, inhoudende de wapenen van vele edele huysen van dese Nederlanden, en[de] andere omliggende [...].
No full textAuthor derived from f. A2Vingerafdruk: 156708 - # b1 A2 ce : # b2 2a4 de$fabHerkomst: Vignet: Ex bibliotheca Ferd. van der Haeghen ; Reinouth van Brederode 1593Cockx-Indestege, E. Belgica typographica 1836Machiels, J. Catalogus van de boeken gedrukt vóór 1600 ; L 104Vanderhaeghen, F. Bib. gantoise 170Europeana-GoogleBooksVander Haeghen, Ferdinand François Ernes
Reexamining “Free Energy Rate Density” as a Complexity Metric
Get PDFCosmic Evolution, by Eric J. Chaisson is arguably one of the original “core” texts of big history. Despite being published over 20 years ago, it is still relevant for its explanation of the cosmological and thermodynamic underpinnings of the evolution of complex systems over the span of time. It was also a pioneering work because it proposed that we can quantify the degree of complexity of systems by determining the quantity of the “free energy rate density” or FERD (abbreviated as “Ωm” in Cosmic Evolution) that flows through a system. Although Chaisson advises that his correlations of FERD to complexity degree is subject to various limitations and generalizations, careful analysis of the arguments and examples used to support FERD indicates that it is even less likely to be as reliable and quantifiable than he purports for at least the following reasons:
1. The author offers a relatively short list of criteria for a system to qualify being “complex” that in turn results in the inclusion of systems that are not classified as complex by usual criteria.
2. Free energy rate density is not compared against other complexity metrics and subsequently seems to serve as its own “gold standard.” The lack of comparisons results in a tautological argument and sometimes questionable conclusions.
3. The argument for FERD sometimes deviates from the hypothesis that FERD is a good way to measure the degree of a system’s complexity to a claim that it also measures complex functions and structures as well.
4. The FERD that he reports are often actually for the total energy flow through a system. Hence, a much more efficient complexity might only appear to be less complex.
5. Complex systems have many variables that can confound attempts to make reliable and precise generalizations, including good metrics for their degree
