620 research outputs found
Design and experimental analysis of modular pedestrian bridge with concrete deck and IPC truss girder
No full textIn the present work the design and experimental analysis of a pedestrian bridge is presented. The actual bridge consists of a supporting truss system built with IPC sandwich panels and a horizontal concrete deck. The [PC is a kind of ceramic which is reinforced with glass fibers. The connection between the sandwich panels the truss system and the concrete deck is done using specially designed steel elements. The aim of this work is the examination of the behavior of the prototype that is constructed and evaluated via static and dynamic tests. The results of the experimental analysis are necessary for the final evaluation of the structure before the construction of bigger bridges and in order to have an overview of the critical areas of the structure that have to be reconsidered during the design phase of a different structure
Prediction of Behaviour of Prestressed Suspension Bridge with Timber Deck Panels
No full textCable truss usage allows developing bridges with reduced requirements for girder stiffness, where overall bridge rigidity is ensured by prestressing of the stabilization cable. The advantages of prestressed suspension trusses to provide required stiffness without massive stiffness girders and the ability of cross-laminated timber to behave in both directions are combined in the analysed structure. Prestressed cable truss with coincident (unclear meaning, difficult to translate) in the centre point of the span main and stabilization cables and vertical suspenders only was considered as the main load carrying system in the considered structure of suspension bridge. Two numerical models evaluated influence of cross-laminated timber deck on the behaviour of prestressed cable truss. Two physical models of the structure with the span equal to 2 m were developed for verification of the numerical models. The first physical model was developed for the case, when panels of the deck are placed without clearances and behaving in the longitudinal direction in compression so as in the transversal direction in bending. The second physical model was developed for the case when panels of the deck are placed with clearances and are behaving in the transverse direction in bending only. The dependences of maximum vertical displacements and horizontal support reaction of the cable truss on the intensity of vertical load in cases of symmetric and unsymmetrical loading were obtained for both physical models. Possibility to decrease the cable truss materials consumption by 17% by taking into account combined work of prestressed cable trusses and cross-laminated timber panels was stated
The technology of composite patches and their structural reliability inspection using infrared imaging
No full textPerformance of ZP-OFDM for vehicular communication
No full textThis thesis is concerned with Evaluation of vehicular Wireless communication with the different type of channel Model, concerned with different estimation and equalisation method for vehicular communication. After a general introduction of the main concept of the Vehicular nets, the principles of wireless communication is described. Wireless Channel model is mentioned at first. Bit Error Rate as a most important metric to evaluate each type of communication channel is explained in a subchapter in second chapter. Inter symbol interference (ISI) is explained as an important phenomenon which occurs because of multipath propagation nature of wireless communication in second chapter. Doppler Effect is the next important explained phenomenon which arises from the mobility of signal scatterers. Finally, in this section, we explained the OFDM channel estimation and equalisation which is one of the main methods in Vehicular communication scenario. In Next chapter, the author introduced the different attempts to vehicular channel modelling concerned the stochastic channel model. The author mentioned the papers which concerned the Doppler Effect in channel modelling and channel simulation in vehicular environment. Afterwards, some of the vehicular channel estimations and equalisations methods are mentioned. At the fourth chapter, we made the simulation in MATLAB with the vehicular channel model, Vehicular - high antenna channel model with the most optimise Doppler frequency for the vehicular scenario which mentioned in the previous chapter. The methods that author used for this evaluation in this thesis for channel identifications and equalisations were zero forcing and overlap add methods based on ZP-OFDM scheme compared with the standard CP-OFDM. In this work, author used for first time the ZP-OFDM-OLA and ZP-OFDM-ZF channel equalizers to compare the result with the standard CP-OFDM. Finally, author compared the Symbol Error Rate (SER) per different SNR in different road environments.Diese Arbeit befasst sich mit der Evaluierung der Fahrzeug-Drahtloskommunikation mit dem verschiedenen Modelltypen, die sich mit einer unterschiedlichen Schätz- und Entzerrungsmethode fu?r die Fahrzeugkommunikation beschäftigt. Nach einer allgemeinen Einfu?hrung des Hauptkonzepts der Vehicle Netze werden die Prinzipien der drahtlosen Kommunikation beschrieben. Drahtloses Kanalmodell wird zuerst erwähnt. Die Bitfehlerrate als wichtigste Metrik zur Bewertung jedes Kommunikationstyps wird in einem Unterkapitel im zweiten Kapitel erläutert. Inter-Symbol-Interferenz (ISI) wird als ein wichtiges Phänomen erklärt, das aufgrund der Mehrwegeausbreitung der drahtlosen Kommunikation im zweiten Kapitel auftritt. Der Dopplereffekt ist das nächste wichtige erklärte Phänomen, das aus der Beweglichkeit von Signalstreuern entsteht. Schließlich, in diesem Abschnitt, erklärten wir die OFDM-Kanalschätzung und Entzerrung, die eine der Hauptmethoden im Vehicle Communication-Szenario ist. Im nächsten Kapitel fu?hrte der Autor die verschiedenen Versuche der Fahrzeugkanalmodellierung ein, die das stochastische Kanalmodell betreffen. Der Autor erwähnte die Papiere, die den Dopplereffekt in der Kanalmodellierung und Kanalsimulation im Fahrzeugumfeld betreffen. Danach werden einige der Fahrzeugkanalschätzungen und -gleichungen genannt. Im vierten Kapitel haben wir die Simulation in MATLAB mit dem Fahrzeugkanalmodell Vehicle - high Antennenkanalmodell mit der optimalen Dopplerfrequenz fu?r das Fahrzeugszenario, das im vorigen Kapitel erwähnt wurde, durchgefu?hrt. Die Methoden, die der Autor fu?r diese Evaluierung in dieser Arbeit fu?r Kanalidentifikationen und -gleichungen verwendet hat, waren null-erzwungene und u?berlappende Add-Methoden basierend auf dem ZP-OFDM-Schema im Vergleich zum Standard-CP-OFDM. In dieser Arbeit verwendet der Autor zum ersten Mal die ZP-OFDM-OLA- und ZP-OFDM-ZF-Kanalentzerrer, um das Ergebnis mit dem Standard-CP-OFDM zu vergleichen. Schließlich verglich der Autor die Symbol Error Rate (SER) pro verschiedenen SNR in verschiedenen Straßenumgebungen. Schlagwörter:Masterarbeit Wien, FH Technikum Wien 201
Image processing techniques for the quantification of defects on aircraft materials obtained from infrared thermographs
No full textTransient thermography in the assessment of various defects under composite aircraft repair patching
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Two-dimensional finite element analysis of composite patch repairs using shell laminate elements
No full textPerformance analysis of the cooperative ZP-OFDM: Diversity, capacity and complexity
No full textIn this paper, we investigate the diversity, capacity and complexity issues of cooperative Zero-Padding (ZP)-Orthogonal FrequencyDivisionMultiplexing (OFDM) communication. We consider cooperative ZP-OFDM communication over a multipath Rayleigh channel and with multiple Carrier Frequency Offsets (CFOs) existing at different relays. We use a cooperative tall Toeplitz scheme to achieve full cooperative and multipath diversity, while simultaneously combat the CFOs. Importantly, this full diversity scheme only requires Linear Equalizers (LEs), such as Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) equalizers, an issue which reduces the system complexity when compared to a Maximum-Likelihood Equalizer (MLE) or other near-MLEs. Theoretical analysis of the proposed cooperative tall Toeplitz scheme is provided on the basis of the analytical upper bound of the channel orthogonality deficiency derived in this paper. Utilizing only low-complexity linear equalizers, theoretical analysis and simulation results show that the proposed Toeplitz scheme achieves the full cooperative, multipath and outage diversity.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
“Generalized” algebraic Bethe ansatz, Gaudin-type models and Zp-graded classical r-matrices
No full textAbstractWe consider quantum integrable systems associated with reductive Lie algebra gl(n) and Cartan-invariant non-skew-symmetric classical r-matrices. We show that under certain restrictions on the form of classical r-matrices “nested” or “hierarchical” Bethe ansatz usually based on a chain of subalgebras gl(n)⊃gl(n−1)⊃...⊃gl(1) is generalized onto the other chains or “hierarchies” of subalgebras. We show that among the r-matrices satisfying such the restrictions there are “twisted” or Zp-graded non-skew-symmetric classical r-matrices. We consider in detail example of the generalized Gaudin models with and without external magnetic field associated with Zp-graded non-skew-symmetric classical r-matrices and find the spectrum of the corresponding Gaudin-type hamiltonians using nested Bethe ansatz scheme and a chain of subalgebras gl(n)⊃gl(n−n1)⊃gl(n−n1−n2)⊃gl(n−(n1+...+np−1)), where n1+n2+...+np=n
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