Search results for "Guide"
showing 10 items of 1478 documents
Corrections to “Multipactor Susceptibility Charts for Ridge and Multi-Ridge Waveguides” [Dec 12 3601-3607]
2014
The authors have detected an error in Section IV-A in the above paper (ibid., vol. 59, no. 12, pp. 3601-3607, Dec. 2012). The analyzed rectangular waveguide in the actual version of the article is the WR137, instead of the WR90. As a consequence, the corrections presented here have to be implemented.
3D simulations and experiments of guided wave propagation in adhesively bonded multi-layered structures
2010
Understanding guided wave propagation in multi-layered plates and interaction with discontinuities can be difficult, as well as the interpretation of the ultrasonic signals. Propagation of guided waves can be studied analytically solving the equations of motion with the proper boundary conditions; nevertheless analytical models can be difficult to solve for complex multi-layered structures or having inner discontinuities. The problem can be efficiently studied using numerical techniques. Simulation of guided wave propagation in multi-layered structures, for ultrasonic waves in the MHz range, is solved here with the finite element analysis based on an explicit integration rule to solve the e…
Noncontact Air-Coupled Guided Wave Ultrasonics for Detection of Thinning Defects in Aluminum Plates
2001
Ultrasonic guided waves are gaining increasing attention for the inspection of platelike and rodlike structures. At the same time, inspection methods that do not require contact with the test piece are being developed for advanced applications. This paper capitalizes on recent advances in the areas of guided wave ultrasonics and noncontact ultrasonics to demonstrate a superior method for the nondestructive detection of thinning defects simulating hidden corrosion in thin aluminum plates. The proposed approach uses micromachined gas (air)-coupled capacitive transducers for the noncontact generation and detection of guided plate waves. Interesting features in the dispersive behavior of select…
Guided Wave Propagation in a Plate Edge and Application to NDI of Rail Base
2012
The analysis of guided wave propagation in a plate edge can be useful for some applications, such as for the inspection of the rail base. Here guided waves generated by a laser beam hitting, on the inclined surface, a solid media with trapezoidal cross-section have been studied. We have found that, for the geometry investigated, two guided waves propagate along both free surfaces of the plate, with same velocity and frequency. The analysis of the trajectories of the two material points, due to waves propagation, shows that the wave packets can be identified as Rayleigh waves. The presence of S0 Lamb mode, with low frequency and low amplitude, has been revealed too. As an example of a possib…
Wideband modeling of cascaded H-plane waveguide junctions using the generalised impedance matrix representation
2009
A strong interest in H-plane waveguide components composed of a large number of cascaded planar junctions is recently renewed. Therefore, the more efficient development of full-wave analysis tools of such devices is again receiving consideration, specially for its potential use within modern design tools. A novel technique for providing the wideband generalised impedance matrix representation of the inductive devices in the form of pole expansions, thus extracting the most expensive computations from the frequency loop is proposed. For such purpose, the whole device is first decomposed into simpler building blocks, i.e. planar junctions and uniform waveguides, which are modelled in terms of…
The Scatter Search Methodology
2011
Scatter search (SS) is an evolutionary approach for optimization. It has been applied to problems with continuous and discrete variables and with a single or multiple objectives. The success of SS as an optimization technique is well documented in a constantly growing number of journal articles and book chapters. This article first focuses on the basic SS framework, which is responsible for most of the outcomes reported in the literature, and then covers advanced elements that have been introduced in a few selected papers, such as the hybridization with tabu search, a well-known memory-based metaheuristic. We consider the maximum diversity problem to illustrate the search elements, methods …
CiceRobot: a cognitive robot for interactive museum tours
2007
PurposeThe aim of this paper is to integrate perception, action and symbolic knowledge to allow an autonomous robot to operate in unstructured environments and to interact with non‐expert users.Design/methodology/approachTo achieve such goals, a cognitive robot architecture is proposed based on the integration between subsymbolic and linguistic computations through the introduction of an intermediate level of representation based on conceptual spaces.FindingsThe architecture has been tested in the CiceRobot project on tasks related to guided tours in the Archaeological Museum of Agrigento. Experimental results show that robot cognitive behaviors allow one to achieve a full functional roboti…
New distributed model for synthesis of classical dual mode filters
2010
Up to now, distributed models for classical dual mode filters have not been developed. In this paper, the whole procedure to derive such distributed models is shown step by step. The resulting formulas are very similar to those standard ones used for in-line filters since the 1960s. Model limitations, very similar to those related to classical formulas, in terms of precision and bandwidth, are pointed out. Finally, two practical examples of distributed models of dual mode filters for satellite transponders with different orders have been extracted.
Fast automated design of waveguide filters using aggressive space mapping with a new segmentation strategy and a hybrid optimization algorithm
2005
Waveguide filters are key elements present in many microwave and millimeter-wave communication systems. In recent times, ever-increasing efforts are being devoted to the development of automated computer-aided design (CAD) tools of such devices. In this paper, a novel CAD tool based on modal analysis methods, which improves the efficiency and robustness of the classical aggressive space-mapping technique, is presented for those purposes. The use of a new segmentation strategy and the hybridization of a specific combination of several well-known optimization algorithms is proposed. The CAD tool has been successfully validated with the practical design of several H-plane coupled cavity filter…
Waveguide filters for satellites
2007
This article describes the historical evolution, and its theoretical and technological features of waveguide filters. All-metal waveguide filters have been widely used in satellite payloads since the advent of the first space communication systems four decades ago. In this period, such technology has been continuously evolving due to the increasing requirements demanded to these components. Special attention has also been paid to present the most recent advances in the development of CAD tools for satellite filters, which are based on full-wave electromagnetic analysis methods. Finally, the compact solutions for the input and output stages of satellite payloads are focused on, thus consider…