This paper presents the details of an experimental investigation on the behaviour of axially loaded concrete-filled stainless steel elliptical hollow sections. The experimental investigation was conducted using normal and high strength concrete of 30 and 100 MPa. The current study is based on stub column tests and is therefore limited to cross-section capacity. Based on the equations proposed by the authors on concrete-filled stainless steel circular columns, a new set of equations for the stainless steel concrete-filled elliptical hollow sections were proposed. From the limited data currently available, the equation provides an accurate and consistent prediction of the axial capacity of the composite concrete-filled stainless steel elliptical hollow sections.

This paper presents the behaviour and design of axially loaded concrete-filled steel tube circular stub columns. The study was conducted over a wide range of concrete cube strengths ranging from 30 to 110 MPa. The external diameter of the steel tube-to-plate thickness (D/t) ratio ranged from 15 to 80 covering compact steel tube sections. An accurate finite element model was developed to carry out the analysis. Accurate nonlinear material models for confined concrete and steel tubes were used. The column strengths and load¿axial shortening curves were evaluated. The results obtained from the finite element analysis were verified against experimental results. An extensive parametric study was conducted to investigate the effects of different concrete strengths and cross-section geometries on the strength and behaviour of concrete-filled compact steel tube circular stub columns. The column strengths predicted from the finite element analysis were compared with the design strengths calculated using the American, Australian and European specifications. Based on the results of the parametric study, it is found that the design strengths given by the American Specifications and Australian Standards are conservative, while those of the European Code are generally unconservative. Reliability analysis was performed to evaluate the current composite column design rules.

Cold-formed steel roof truss systems that use complex stiffener patterns in existing hat shape members for both top and bottom chord elements are a growing trend in the North American steel framing industry. When designing cold-formed steel sections, a structural engineer typically tries to improve the local buckling behavior of the cold-formed steel elements. The complex hat shape has proved to limit the negative influence of local buckling, however, distortional buckling can be the controlling mode of failure in the design of chord members with intermediate unbraced lengths. The chord member may be subjected to both bending and compression because of the continuity of the top and bottom chords. These members are not typically braced between panel points in a truss. Current 2001 North American Specifications (NAS 2001) do not provide an explicit check for distortional buckling. This dissertation focuses on the behavior of complex hat shape members commonly used for both the top and bottom chord elements of a cold-formed steel truss. The results of flexural tests of complex hat shape members are described. In addition, stub column tests of nested C-sections used as web members and full scale cold-formed steel roof truss tests are reported. Numerical analyses using finite strip and finite element procedures were developed for the complex hat shape chord member in bending to compare with experimental results. Both elastic buckling and inelastic postbuckling finite element analyses were performed. A parametric study was also conducted to investigate the factors that affect the ultimate strength behavior of a particular complex hat shape. The experimental results and numerical analyses confirmed that modifications to the 2001 North American Specification are necessary to better predict the flexural strength of complex hat shape members, especially those members subjected to distortional buckling. Either finite strip or finite element analysis can be used to better predict the flexural strength of complex hat shape members. Better understanding of the flexural behavior of these complex hat shapes is necessary to obtain efficient, safe design of a truss system. The results of these analyses will be presented in the dissertation. / Ph. D.

Phase shifters are common microwave circuit devices, which are widely used in telecommunication and radar applications, microwave measurement systems, and many other industrial applications. They are key circuits of T/R modules and are used to form the main beam of the electronically scanned phase array antennas. Wideband operating range is an important criterion for EW applications. Hence, wideband performance of the phase shifter is also important. In this study, four wideband phase shifter circuits are designed, fabricated and measured for 6-18 GHz frequency range. Phase shifters are separately designed in order to get 11.25, 22.5, 45 and 90&ordm / phase shifts with minimum phase error and low return losses. Phase shifter circuits are designed and fabricated in microstrip structure onto two different substrates as Rogers TMM10i and Alumina using printed circuit board and thin film production techniques, respectively. Also phase shifter circuits that include microstrip spiral inductors for DC biasing are designed and fabricated using thin film production technique. For each design the fabricated circuits are measured and results are compared with simulation results in the content of this thesis. Circuit designs and EM simulations are performed by using ADS2008&reg / , Sonnet&reg / , and CST&reg / .

This master's thesis describes the possibility of using a continues integration and testing in real company Logio. The result of thesis is implementation of continuous integration tools Jenkins and specific testing for the company Logio. The theoretical part deals with basic principles, techniques and tools defining continuous integration. Subsequently are describing existing tools designed for PHP programming language. The thesis also analyzes various types and possibilities of application testing. Also explains the problems in product development in company Logio, which are consequence of the need for introducing continues integration techniques. The practical part of thesis describes the implementation of a test framework PwTester and its use in continuous integration. In conclusion, the results are evaluated and outlined the possibility of extension.

This paper describes the finite element method using ABAQUS to model the axial compressive behaviour of inclined, tapered and straight-tapered-straight (STS) concrete filled steel tubular stub (CFST) columns with square hollow sections. The accuracy of the numerical model was verified by comparing the numerical predictions with experimental study of the 200×200×3.75 RHS filled with C60 concrete with inclined angle of 0-9° and tapered angle of 0-4°. The results show that the compressive behaviours, load vs. strain relationship and failure mode predicted by the numerical simulations were agreeable with experimental results. After the validation, a parametric study was performed with 3 typical steel hollow sections (200×200×3.75 RHS, 300×300×6.3 RHS and 400×400×8.0 RHS) and extended the inclined angle and tapered angle to 0-15° and 0-12° respectively. The parametric study highlights some of the behaviour observed in test and extends the application range. In addition, reduction factor for calculating the axial capacity of this form of CFST columns are proposed.

No / A novel multi-standard dual-wide band filter with a compact size of only 8.8 mm by 16.8mm is designed and developed for transceiver devices. The proposed filter has a fundamental bandwidth of 1.6GHz with fractional bandwidth (FBW) of 29.7% centered at the 5.4GHz band, and second bandwidth of 300.0MHz with FBW of 3.6% centered at the 8.15GHz band. The basic dual-wide bandwidth is attributed to the interaction of the novel modified polygon pair and upper stub loaded stepped impedance resonator. Moreover, the added down stub loaded stepped impedance resonator (SLSIR) further enhances the pass band performance by widening the bandwidth and optimizing reflection coefficient performance considerably. To validate the proposed ideas, the multi-standard filter is designed and simulated by Ansoft HFSS software. The simulated results agree well with the theory predictions. The featured broad bandwidths over two frequency bands and the miniaturized size of the proposed filter make it very promising for applications in future multi-standard wireless communication.

<p>У овом раду спроведене су опсежна експериментална и нумеричка<br />испитивања понашања веза са чеоном плочом и четири завртња у реду,<br />као и карактеристичне компоненте ових веза - Т-елемента.<br />Експериментална испитивања укључују тестирања 36 узорака<br />Т-елемената у природној величини, као и четири везе греда-стуб са<br />чеоном плочом и четири завртња у реду, такође у природној величини.<br />Нумеричке анализе, спроведене у софтверском пакету ABAQUS, су<br />обухватале све типове нелинеарности, али и отказ материјала, те се као<br />такве сврставају међу ретке којима су слични проблеми нумерички<br />испитивани. Параметарска студија обухвата 33 различите конфигурације<br />Т-елемената са четири завртња и представља највећу такву студију<br />изведену за ову компоненту. Као основни још увек нерешен проблем,<br />круцијалан за понашање Т-елемената, препознати су положај сила услед<br />ефеката полуге, али и савијање завтњева. Приказан је и предложен нови<br />аналитички модел прорачуна носивости Т-елемената са четири завртња,<br />и квантификована његова предност над до сада постојећим моделима.</p> / <p>U ovom radu sprovedene su opsežna eksperimentalna i numerička<br />ispitivanja ponašanja veza sa čeonom pločom i četiri zavrtnja u redu,<br />kao i karakteristične komponente ovih veza - T-elementa.<br />Eksperimentalna ispitivanja uključuju testiranja 36 uzoraka<br />T-elemenata u prirodnoj veličini, kao i četiri veze greda-stub sa<br />čeonom pločom i četiri zavrtnja u redu, takođe u prirodnoj veličini.<br />Numeričke analize, sprovedene u softverskom paketu ABAQUS, su<br />obuhvatale sve tipove nelinearnosti, ali i otkaz materijala, te se kao<br />takve svrstavaju među retke kojima su slični problemi numerički<br />ispitivani. Parametarska studija obuhvata 33 različite konfiguracije<br />T-elemenata sa četiri zavrtnja i predstavlja najveću takvu studiju<br />izvedenu za ovu komponentu. Kao osnovni još uvek nerešen problem,<br />krucijalan za ponašanje T-elemenata, prepoznati su položaj sila usled<br />efekata poluge, ali i savijanje zavtnjeva. Prikazan je i predložen novi<br />analitički model proračuna nosivosti T-elemenata sa četiri zavrtnja,<br />i kvantifikovana njegova prednost nad do sada postojećim modelima.</p> / <p>In this research, extensive experimental and numerical investigations of<br />behaviour of end-plate moment connection with four bolts per row are<br />performed, as well as specific component of the connection &ndash; T-stub element.<br />Experimental research comprises tests on 36 unscaled specimens of T-stub<br />elements and 4 specimens of beam-to-column joints with end-plate connection<br />and four bolts per row, also in full-size. Numerical analyses, performed with<br />software ABAQUS, included all types of nonlinearities, and material<br />deterioration, hence they can be considered as one of the few most<br />sophisticated analyses used for investigation of the considered problem. The<br />parametric study comprises 33 different configurations of the T-stub element<br />with four bolts per row and it presents the biggest study of this kind for this type<br />of component. Bending of the bolts and position of the prying forces are<br />recognized as the largest, still unsolved problem, crucial for the behavior of the<br />T-stub elements. A new theoretical model for the resistance of the T-stub<br />element with four bolts per row is proposed and its advantage over the existing<br />models is presented and quantified.</p>

<p>In this Master thesis, microwave connections between circuit boards are constructed. The primary frequency band is the X-band (8-12 GHz). The purpose of the connections is to enable a more simple and cheaper way of mounting the circuit boards inside a container. </p><p>The connections have been designed and evaluated, using different computer programs. A few prototypes have been built and measured. </p><p>The main goal of this Master thesis was to design a connection, that would be useful in practice. The connections should be easy to manufacture and have a good performance. They should also have a high tolerance for manufacturing errors. </p><p>The main part of this report contains descriptions of different designs. The designs are presented together with simulated and measured results. </p><p>The report contains designs based upon coplanar waveguides and a phase shifting technique. The result shows that designs that are using coplanar waveguides are good. The phase shifting technique has some limitations and need to be developed further.</p>

Communication and reconnaissance systems are requiring increasing flexibility concerning functionality and efficiency for multiband and broadband frequency applications. Circuit-based reconfiguration mechanisms continue to promote radio frequency (RF) application flexibility; however, increasing limitations have resulted in hindering performance. Therefore, the implementation of a "wireless" reconfiguration mechanism provides the required agility and amicability for microwave circuits and antennas without local overhead. The wireless reconfiguration mechanism in this thesis integrates dynamic, fluidic-based material systems to achieve electromagnetic agility and reduce the need for "wired" reconfiguration technologies. The dynamic material system component has become known as electromagnetically functionalized colloidal dispersions (EFCDs). In a microfluidic reconfiguration system, they provide electromagnetic agility by altering the colloidal volume fraction of EFCDs - their name highlights the special considerations we give to material systems in applied electromagnetics towards lowering loss and reducing system complexity. Utilizing EFCDs at the RF device-level produced the first circuit-type integration of this reconfiguration system; this is identified as the coaxial stub microfluidic impedance transformer (COSMIX). The COSMIX is a small hollowed segment of transmission line with results showing a full reactive loop (capacitive to inductive tuning) around the Smith chart over a 1.2 GHz bandwidth. A second microfluidic application demonstrates a novel antenna reconfiguration mechanism for a 3 GHz microstrip patch antenna. Results showed a 300 MHz downward frequency shift by dielectric colloidal dispersions. Magnetic material produced a 40 MHz frequency shift. The final application demonstrates the dynamically altering microfluidic system for a 3 GHz 1x2 array of linearly polarized microstrip patch antennas. The parallel microfluidic capillaries were imbedded in polydimethylsiloxane (PDMS). Both E- and H-plane designs showed a 250 MHz frequency shift by dielectric colloidal dispersions. Results showed a strong correlation between decreasing electrical length of the elements and an increase of the volume fraction, causing frequency to decrease and mutual coupling to increase. Measured, modeled, and analytical results for impedance, voltage standing wave ratio (VSWR), and radiation behavior (where applicable) are provided.