Highly efficient frequency triplers in the millimeter wave region incorporating a back-to-back configuration of two varactor diodes

This paper reports on the recent development of monolithic frequency tripler array employing a back-to-back configuration of varactor diodes. Even harmonic idler circuits are unnecessary in this design. Furthermore, no external dc bias is required. The arrangement results in highly efficient, easily-fabricated and inexpensive frequency triplers

Quasi-optical watt-level millimeter-wave monolithic solid-state diode-grid frequency multipliers

A monolithic planar array containing thousands of GaAs Barrier-Intrinsic-N^+ diodes have produced one watt output power at 100 GHz in a tripler configuration. Tripling efficiency of 8.5% has been obtained from approximately 4-mW incident power on each diode, in excellent agreement with the predictions of large-signal nonlinear circuit analysis of frequency multiplication. The device performance is limited by the parameters of the fabricated diodes. Significant improvement is expected with realizable diode parameters and optimized pumping condition

Response characteristics in the apex of the gerbil cochlea studied through auditory nerve recordings

In this study, we analyze the processing of low-frequency sounds in the cochlear apex through responses of auditory nerve fibers (ANFs) that innervate the apex. Single tones and irregularly spaced tone complexes were used to evoke ANF responses in Mongolian gerbil. The spike arrival times were analyzed in terms of phase locking, peripheral frequency selectivity, group delays, and the nonlinear effects of sound pressure level (SPL). Phase locking to single tones was similar to that in cat. Vector strength was maximal for stimulus frequencies around 500 Hz, decreased above 1 kHz, and became insignificant above 4 to 5 kHz. We used the responses to tone complexes to determine amplitude and phase curves of ANFs having a characteristic frequency (CF) below 5 kHz. With increasing CF, amplitude curves gradually changed from broadly tuned and asymmetric with a steep low-frequency flank to more sharply tuned and asymmetric with a steep high-frequency flank. Over the same CF range, phase curves gradually changed from a concave-upward shape to a concave-downward shape. Phase curves consisted of two or three approximately straight segments. Group delay was analyzed separately for these segments. Generally, the largest group delay was observed near CF. With increasing SPL, most amplitude curves broadened, sometimes accompanied by a downward shift of best frequency, and group delay changed along the entire range of stimulus frequencies. We observed considerable across-ANF variation in the effects of SPL on both amplitude and phase. Overall, our data suggest that mechanical responses in the apex of the cochlea are considerably nonlinear and that these nonlinearities are of a different character than those known from the base of the cochlea

Utilising a safety culture approach in the Australian construction industry

New innovations in health and safety management are required to further reduce injuries and fatalities in the Australian construction industry. Current approaches to safety management emphasise hazard identification and reduction, but fail to fully account for a worker’s motivation to behave safely. In order to understand and improve safety motivation, many researchers and practitioners are utilising the construct of safety culture. Unfortunately, the transitory nature of work within the industry frequently hinders an organisation’s attempts to develop and maintain a good safety culture. Hence, a framework is needed to facilitate the formation of a good safety culture across the construction industry as a whole. A methodology is advanced as to how culture change can be facilitated by using a system of competencies developed and applied to the key safety roles within the industry. This set of nationally standardised and accepted competencies would specifically state what is required by those who have safety critical roles, to positively influence construction site safety culture. By encouraging organisations to integrate these competencies into their existing HRM processes such as selection, training and performance management, it should be possible to (1) educate the industry as to best practice in safety culture management, (2) provide a safety culture management system that allows a good safety culture to be built quickly on new projects, (3) ensure a standard level of competency within the workforce to allow for ease of movement of workers between sites and contractors, and (4) improve safety culture and in turn potentially improve safety on-site

Safety leadership and the project manager : competencies required to positively affect site safety culture

An arguable means to address injury and fatality rates in the Australian construction industry is the improvement of site safety culture. When understanding how safety culture is influenced, it is important to note the significant role that both management and leadership have in determining the quality of a safety culture. Focus groups were conducted with eleven of Australia's largest construction contractors with the purpose of identifying safety critical positions and the characteristics, competencies and attitudes required by people who hold these roles, to be successful safety leaders. Analysis of the results revealed the important position that Project Managers are in to effectively lead safety behaviours, as well as the strong role that safety knowledge, communication and interpersonal style have in determining the quality of their safety leadership