A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Digital processing of speech signals

Computer and Robot Vision Vol. 1, by R.M. Haralick and Linda G. Shapiro, Addison-Wesley, 1992, ISBN 0-201-10887-1.

Computer and Robot Vision

Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)

An electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated. The advantage of the power control system is that thermal spread and charring are reduced. In addition, the power control system offers improved performance for electrosurgical vessel sealing and tissue welding. The output power is applied cyclically by a control system with tissue impedance feedback. The impedance of the tissue follows the cyclic pattern of the output power several times, depending on the state of the tissue, until the tissue becomes fully desiccated. High power is applied to cause the tissue to reach a high impedance, and then the power is reduced to allow the impedance to fall. Thermal energy is allowed to dissipate during the low power cycle. The control system is adaptive to tissue in the sense that output power is modulated in response to the impedance of the tissue.

Electrosurgical generator with adaptive power control

With an Optical feedback interferometry (OFI), a self-mixing signal (SMS) can be observed and employed to determine parameters of the semiconductor laser and metrological quantities of an object. In the cases of the measurement of the movement trace of an external target, phase unwrapping of the SMS must be performed, which remains a challenging issue. We report a technique for achieving phase unwrapping of the SMS signals as follows. Firstly, the behaviour of the phase equation of the OFI is studied, based on which general laws for laser phase change with respect to external target movement is extracted. Secondly, the correlation between the laser phase change and SMS signal is studied. Finally phase unwrapping algorithm is developed based on the relationship. In order to make sure that the proposed approach works well in the cases of noisy SMS data, pre-processing algorithms are also discussed. The proposed techniques have been tested by both computer simulation and experimental data which show that excellent agreement can be achieved and the movement trace of the external target can be retrieved.

/pdf/phase-unwrapping-of-self-mixing-signals-observed-in-optical-1o0xrofuox.pdf

Phase Unwrapping of Self-mixing Signals Observed in Optical Feedback Interferometry for Displacement Measurement

The paper presents a new approach for measuring the linewidth enhancement factor (LEF) of semiconductor lasers (SL) and the optical feedback level factor C in SLs. The proposed approach is based on the analysis of self-mixing signals observed in self-mixing optical feedback interferometry. Unlike existing approaches, the approach tries to estimate the parameters LEF and C by a gradient-based optimization algorithm that achieves best data-to-theoretical model fitting. The effectiveness and accuracy of the method have been confirmed and tested by theoretical analysis and computer simulations

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=10206&context=infopapers

Estimating the Parameters of Semiconductor Lasers Based on Weak Optical Feedback Interferometry

Multi-wire steel strands have been widely used in various prestressed concrete structures. In this study, experimental evaluation of fiber Bragg grating (FBG) sensors for strain measurements in a seven-wire prestressed steel strand has been carried out. An installation technique of FBG sensors has been developed to fulfill the special requirements of the prestressed steel strand. The experiment results show that fiber Bragg gratings can represent the overall stress of the prestressed steel strand without being affected by the specific structure of the strand when it is only fixed on one wire. It is also demonstrated that the maximum strain that the FBG sensor can measure is 6260 μe, while the prestressed steel strand usually endures the strain greater than 10000 μe. This means that an offset of about 4000 μe is necessary to measure the maximum strain that the strand could experience in its applications.

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=10165&context=infopapers

The experimental evaluation of FBG sensor for strain measurement of prestressed steel strand

Topology control in an ad-hoc network can provide better spatial reuse of the wireless channel and conserve power. Topology construction and maintenance is a challenging issue. A number of distributed topology control algorithms have been proposed to remove the need of a centralised controller. Distributed algorithms such as location information no topology (LINT), location information link state topology (LILT) and mobile-grid (MG), aim to achieve overall network connectivity and low transmission range by maintaining a minimum node degree value. In the case of a non-uniform node distribution, maintaining a minimum node degree can unnecessarily partition a network. In this paper, we propose a distributed algorithm that utilises one hop neighbours and their location information to maintain a number of critical links required to keep a connected network. Such critical links are included along with the links required to meet the node degree criterion. A distributed mechanism to construct and maintain a network topology is proposed, which can be integrated as part of the neighbour discovery protocol. Furthermore, nodes collaborate to remove unidirectional links. A simulation based analysts of the proposed algorithm is provided for a number of node degree values. Simulations indicate that the proposed algorithm is able to achieve higher connectivity for different node distributions.

/pdf/topology-control-in-heterogeneous-ad-hoc-networks-1h6vs7tyx0.pdf

Topology control in heterogeneous ad-hoc networks

This paper presents a new routing strategy for heterogeneous mobile ad hoc networks. We refer to this strategy as on-demand utility-based routing protocol (OUBRP). This protocol introduces a utility-based route discovery strategy, which aims to minimise the number of control packets disseminated into the network during route discovery by efficiently using available resources at each node. Furthermore, we propose a new strategy to eliminate uni-directional links during the route discovery phase. We refer to this strategy as uni-directional link elimination (ULE). We performed a simulation study to compare the performance of OUBRP with a number of different routing protocols proposed for MANETs. Our results show that OUBRP compared to other routing strategies produces significantly fewer control packets and achieves higher levels of successful packet delivery with increasing number of nodes. Furthermore, we propose a number of alternative uni-directional link elimination strategies.

/pdf/a-routing-strategy-for-heterogeneous-mobile-ad-hoc-networks-4n88a4ggw5.pdf

Joe F. Chicharo

Papers

Phase Unwrapping of Self-mixing Signals Observed in Optical Feedback Interferometry for Displacement Measurement

Estimating the Parameters of Semiconductor Lasers Based on Weak Optical Feedback Interferometry

The experimental evaluation of FBG sensor for strain measurement of prestressed steel strand

Topology control in heterogeneous ad-hoc networks

A routing strategy for heterogeneous mobile ad hoc networks