A mode-matching technique for the study of circular and coaxialwaveguide discontinuities based on closed-form coupling integrals

A mode-matching scheme for the analysis of concentric circular and/or coaxial waveguide step discontinuities is proposed in this paper. An analytical evaluation of the involved coupling integrals for all possible discontinuities formed by any combination of a circular and a coaxial waveguide is performed. The originality mainly concerns the multimode excitation and scattering at a circular-to-coaxial waveguide step junction. Numerical results for a number of applications are compared against those of other techniques and/or measurements and are found to be in good agreement     

Mode matching analysis of multiple offset coaxial irises in circular waveguide

The step junction between a circular and an eccentric coaxial waveguide is analysed using a rigorous mode matching technique along with the Graff's addition theorem for cylindrical functions. The necessary expressions including the coupling integrals are considered analytically. Based on this analysis the off-centred coaxial iris in a circular waveguide is studied. Its properties are pointed out and the single and dual irises on the same diaphragm features are exploited for the design of bandpass filters.     

Stainless steel coupled with carbon nanotube-modified epoxy and carbon fibre composites: Electrochemical and mechanical study

The aim of this work is the study of the electrochemical and mechanical behaviour of stainless steel (SS304) adhesively bonded with carbon nanotube (CNT)-reinforced epoxies to either SS304 or carbon-reinforced composites substrates. For metal to metal (MtM) joints, the shear strength of nano-reinforced adhesives was studied using single lap shear specimen geometries. The lap shear strength was improved by almost 50% and the highest shear strength appeared for 0.6% CNT weight content in the adhesive. The metal to composite joint performed altogether better compared to the MtM joint, although the CNT inclusion had an adverse effect on the lap shear strength attributed to the physical property change of the epoxy. Although the incorporation of CNTs was found to increase the galvanic effect, it also enhanced corrosion protection, as the modified adhesives exhibited increased resistance to uniform corrosion and localised corrosion and prevented the electrolyte from reaching the substrate.     

An exact solution of the time-invariant discrete Kalman filter

An exact solution is presented of the matrix Riccati difference equation associated with a time-invariant discrete Kalman filter. The time-varying solution is expressed by means of the corresponding steady-state algebraic solution. An exact solution of the closed-loop transition matrix is also presented.