10 research outputs found
Evaluierung der Implementierung nichtlinearer Stabstatik in kommerzieller Software
No full textIn der vorliegenden Bachelor Thesis wird die Evaluierung der Implementierung nichtlinearer Stabstatik in kommerzieller Finite-Elemente-Software behandelt. Dabei werden die Programme SOFiSTiK und Dlubal RSTAB auf ihren Umgang mit geometrisch nichtlinearen Problemen geprüft; halten die Programmhersteller tatsächlich dies, was sie bezüglich der geometrisch nichtlinearen Tragwerksberechnung versprechen, auch ein? Um auf diese Frage eine Antwort zu finden, werden verschiedene Beispiele, bei denen die geometrische Nichtlinearität einen wichtigen Faktor darstellt, berechnet. Die Arbeit ist folgendermaßen konzipiert: Da bereits bezüglich der Definitionen geometrischer Nichtlinearität Uneinigkeit herrscht, werden diese und ihre Erscheinungsformen nach wissenschaftlicher Definition abgegrenzt und erläutert. Da die Theorie II. Ordnung eine der grundlegenden Berechnungstheorien für geometrische nichtlineares Verhalten darstellt und im Bauingenieurwesen am häufigsten Anwendung findet, wenn es um nichtlineare Berechnungen geht, wird die Differentialgleichung der linearisierten Theorie II. Ordnung hergeleitet. Ihre Annahmen und Schranken werden hervorgehoben, da diese sich maßgeblich auf die Finite-Elemente-Implementierung auswirken. Um die Evaluierung durchzuführen, werden Systeme bezüglich ihrer Antwortgrößen, also den Schnittgrößen und Verschiebungen analysiert. Zu den Systemen bestehen in der Regel Referenzlösungen, deren Vergleich mit den erzielten Ergebnissen in den Programmen Aufschluss darüber geben, wie genau und effizient die kommerzielle Software mit den geometrisch nichtlinearen Problemen umgeht. Daraus sollen Schlüsse auf die Implementierung gezogen werden; eine exakte Erfassung der Implementierung ist hier nicht Gegenstand der Arbeit und würde einen Einblick in die Programmcodes erfordern. Es wird analysiert, welche Parameter eine besondere Sensitivität für die Programme darstellen und ob die Behauptungen der Programme bezüglich der Leistungsfähigkeit stimmen. Letztendlich wird zusammengetragen, was für Probleme von den Programmen erfasst werden können. Darüberhinaus wird hevorgehoben, was die Programme nicht richti
Material Monitoring of a Composite Dome Pavilion Made by Robotic Coreless Filament Winding
Get PDFA hemispherical research demonstration pavilion was presented to the public from April to October 2019. It was the first large-scale lightweight dome with a supporting roof structure primarily made of carbon- and glass-fiber-reinforced composites, fabricated by robotic coreless filament winding. We conducted monitoring to ascertain the sturdiness of the fiber composite material of the supporting structure over the course of 130 days. This paper presents the methods and results of on-site monitoring as well as laboratory inspections. The thermal behavior of the pavilion was characterized, the color change of the matrix was quantified, and the inner composition of the coreless wound structures was investigated. This validated the structural design and revealed that the surface temperatures of the carbon fibers do not exceed the guideline values of flat, black façades and that UV absorbers need to be improved for such applications
Polynomial J-spectral factorization method for optimal control of discrete-time systems
No full textDimirovski, Georgi M. (Dogus Author)We present a simple algorithm for linear-quadratic control of discrete-time systems, based on polynomial J-spectral factorization
Additive Manufacturing in Construction—Implementing Powder-Bed Fusion of Metals Using a Laser (PBF-LB/M) and Shape Optimization in the Construction Design Process
No full textIn this study, the implementation of the PBF-LB/M process into the construction design and building process was investigated. To this purpose, a tensegrity-tower was designed, planned, and built. The nodes between the compression rods and the tension cables were manufactured by PBF-LB/M/AlSi10Mg. Four different nodes were designed and shape-optimized by vertex-morphing. In order to qualify the tensegrity nodes according to the German regulations, mechanical as well as microstructural evaluations were conducted. Tensile tests of a manufactured tensegrity node in a fully hinged setup were carried out. Additionally, fatigue testing was conducted. The tensegrity nodes were heat-treated (T6) and subsequently vibratory ground to reduce the surface roughness. The results indicate that it is feasible to integrate the PBF-LB/M process into the design and construction process. The tower is now a permanent and tangible exhibit in the Deutsches Museum in Munich
Philippine democracy reexamined
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This article appeared in an offprint of the journal Historical Bulletin, with the title "Philippine Democracy Reexamined"With lucid and alarming candor, the author cites unconscious habits and attitudes, as well as powerful social forces, that resist the growth of democracy here. He reveals the immaturity of our people in many significant ways and feels that democracy doesn’t work in the Philippines because it can’t. However, he says that if our people and institutions are honest enough to recognize and admit the serious shortcomings, then there might be hope. Otherwise, he views, with characteristic mordancy, that the deepening shadows of authoritarianism will continue to lengthen. Evolution as an engine of change, rather than armed revolution, might be the way out, provided our society can wake up and be resilient to transform its present undemocratic spirit.
To the question—Does democracy work in the Philippines?— the answer could well be yes and no, probably more no than yes. Or a better answer might be, superficially yes. And very seriously, no.
If the question were phrased differently—“Can democracy work here?” — the answer would have to deal with the ability and power of the people to make it work. That ability and that power are shaped and limited by the framework of the prevailing institutions. Therefore, the answer in essence could well be the same, “Democracy doesn’t work here because it can’t.” It can’t, because of the character of the framework
Regularity conditions for control problem with descriptor systems
No full textDimirovski, Georgi M. (Dogus Author) -- Conference full title: 14th IEEE International Conference on Control and Automation, ICCA 2018; Anchorage; United States; 12 June 2018 through 15 June 2018.We present a practical method for solving the measurement feedback control problems with a desriptor standard control structure (SCS) through their transformation into problems with a state-space (SCS). We motivate by an example and define regularity conditions for descriptor SCS, and prove that the original descriptor SCS is regular if and only if the transformed by our algorithm state-space SCS is regular. The elaborated overall method for finding optimal controllers for descriptor systems simplifies all existing methods. Numerical examples are given, which illustrate the paper’s results
Optimal tracking and disturbance rejection with invariant zeros on the unit circle: a polynomial spectral factorization design
No full textDimirovski,Georgi M. (Dogus Author) -- Conference full title: 20th IFAC World Congress, Toulouse, France ; 9 July 2017 thorugh 14 July 2017We present a simple algorithm for computation of H2-optimal tracking and disturbance rejection controller of discrete-time systems possessing invariant zeros on the unit circle, based on polynomial spectral factorization. We prove that the column degrees of the associated para-hermitian polynomial matrix to be factorized are equal to the plant controllability indices. A numerical/computer simulation example is given
Correction: Author Correction: Somatic chromosomal engineering identifies BCAN-NTRK1 as a potent glioma driver and therapeutic target
No full textNature Communications 8: Article number: 15987 (2017); Published: 11 July 2017; Updated: 13 March 2018 In the original version of this Article, financial support was not fully acknowledged. The PDF and HTML versions of the Article have now been corrected to include the following: ‘This work was supported by grant I10-0095 from the STARR foundation.</jats:p
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