Impulse TDR and its application to measurement of antennas

The traditional stimulus signal used in a time-domain reflectometer (TDR) is a voltage step. We propose an alternative technique, whereby an impulse generator is employed in place of the step generator in a TDR. The advantage conferred by “impulse TDR” is that more energy is available at higher frequencies than with conventional step TDR, and so a higher bandwidth and signal-to-noise ratio (SNR) is achieved. The theoretical result is compared with measurement

Measurement of antennas and microwave components using time-domain reflectometry of a voltage impulse

Band-pass microwave systems such as ultra-wideband antennas are traditionally characterized in the frequency-domain through a vector network analyzer in an anechoic chamber. A recent study proved antennas could be accurately measured in the time-domain using a step-function time-domain reflectometer (TDR), without the need for an anechoic chamber. We propose a new advance in the TDR characterization method. An impulse generator is employed in place of the step generator in a TDR set-up. The advantage conferred by this change is that more energy is available beyond a given frequency than with a step, and so a higher signal-to-noise ratio is achieved. The theoretical result is compared with measurement

Cause and Amelioration of MRI-Induced Heating Through Medical Implant Lead Wires

The RF fields present in magnetic resonance imaging (MRI) scanners can induce hazardous heating in patients wearing medical implants. The inherent design and locale of deep brain stimulators (DBS) and spinal cord stimulators (SCS) make them particularly susceptible. We apply antenna concepts and use electromagnetic (EM) simulation to explain the phenomenon and anticipate its sensitivity to lead wire length. We anticipate that a DC resistance of less than 50 Ω/m and an RF impedance of more than 1:23kΩ/m would be required for a safe electrode for SCS use. We investigate the possibility of manipulating wire conductivity and diameter in order to use the skin depth effect to achieve a safe electrode. The effect of the thickness and permittivity of insulation surrounding the wires is explored

A coevolutionary framework for engaging trading partners in interorganisational e-commerce

University of Technology, Sydney. Faculty of Information Technology.The objective of this research was to produce a better understanding of the way trading partners engage in interorganisational e-commerce systems in order to help practitioners. An interpretive philosophical approach was taken via an empirical study of ten e- commerce interorganisational systems, spanning a variety of technological approaches, trading scenarios and industry settings. Using semi-structured interviews, qualitative data were collected and a thematic analysis undertaken. The results suggested coevolutionary theory as a useful perspective for understanding the context. An in-depth case study was then used to build a detailed coevolutionary interpretation for the history of change, technological development and engagement in a single system. The resulting framework incorporates social and technological components in a three level coevolutionary hierarchy. The e-commerce system is reconceptualised as a socio- technical trading system, and the move to Internet based trading operations as part of the ongoing evolution of that system. Under this interpretation interdependencies and coevolutionary effects, both between components and between levels, lie at the heart of understanding why trading partners are successfully or unsuccessfully engaged in e- commerce. Successful engagement is characterised by positive feedback loops, and failure is characterised by negative feedback loops and whole-part coevolutionary competition

The relaxation of OH (v = 1) and OD (v = 1) by H2O and D2O at temperatures from 251 to 390 K

We report rate coefficients for the relaxation of OH(v = 1) and OD(v = 1) by H2O and D2O as a function of temperature between 251 and 390 K. All four rate coefficients exhibit a negative dependence on temperature. In Arrhenius form, the rate coefficients for relaxation (in units of 10–12 cm3 molecule–1 s–1) can be expressed as: for OH(v = 1) + H2O between 263 and 390 K: k = (2.4 ± 0.9) exp((460 ± 115)/T); for OH(v = 1) + D2O between 256 and 371 K: k = (0.49 ± 0.16) exp((610 ± 90)/T); for OD(v = 1) + H2O between 251 and 371 K: k = (0.92 ± 0.16) exp((485 ± 48)/T); for OD(v = 1) + D2O between 253 and 366 K: k = (2.57 ± 0.09) exp((342 ± 10)/T). Rate coefficients at (297 ± 1 K) are also reported for the relaxation of OH(v = 2) by D2O and the relaxation of OD(v = 2) by H2O and D2O. The results are discussed in terms of a mechanism involving the formation of hydrogen-bonded complexes in which intramolecular vibrational energy redistribution can occur at rates competitive with re-dissociation to the initial collision partners in their original vibrational states. New ab initio calculations on the H2O–HO system have been performed which, inter alia, yield vibrational frequencies for all four complexes: H2O–HO, D2O–HO, H2O–DO and D2O–DO. These data are then employed, adapting a formalism due to Troe (J. Troe, J. Chem. Phys., 1977, 66, 4758), in order to estimate the rates of intramolecular energy transfer from the OH (OD) vibration to other modes in the complexes in order to explain the measured relaxation rates—assuming that relaxation proceeds via the hydrogen-bonded complexes

The Politics of Innovation: Realising the Value of Intrapreneurs

This paper offers three cases, from very different industries, where an organisation failed to realise the value of the talent that was recruited at significant cost to lead an attempt at innovation. In each case, the recruited talent was forced into an intrapreneurial role - one in which they had to operate below the management radar - in order to attempt to progress the project for which they were employed. Furthermore, in each case, senior management at the company failed to scrutinise its management practices with respect to the constraints they unwittingly imposed upon the newly recruited person. Through its analysis of the reasons for each of these failures, the paper highlights the dynamics of effective talent management in the knowledge era, and points to alternative leadership practices through which to realise the value offered by talented staff recruited specifically to lead an organisation's strategic intent to innovate

ENROLLING ACTORS IN THE CO-EVOLUTON OF INTER-ORGANISATIONAL INFORMATION SYSTEMS

This paper describes interpretive case-study research into the development on some e-commerce inter-organisational information systems (EIOS) implemented in Australia. The research was undertaken in two phases, firstly a thematic analysis in ten organisations, and secondly an in-depth case study of one of these organisations using co-evolutionary theory. A framework of EIOS evolution is developed and offered as a tool for practitioners working as initiators of EIOS