− The lock-in amplifier, working at acoustic frequency range, can be cheaply realized by applying a sound card or a board kit with a digital signal processor, together with a low noise amplifier. Such realization can automatically retune frequency and can perform fast measurements at various frequencies to establish frequency characteristic of the investigated, and often time-varying, object. Q...

Volterra series have been in the engineering literature for some time now, and yet there have been few attempts to measure Volterra kernels. This paper discusses techniques for measuring the Volterra kernels of weakly nonlinear systems. We introduce a new quick method for measuring the second Volterra kernel which is analogous to pseudo-noise testing of a linear device. To illustrate the discus...

This paper presents a new control structure to reduce torque ripple in switched reluctance motor. Although SRM possesses many advantages in motor structure, it suers from large torque ripple that causes some problems such as vibration and acoustic noise. In this paper another control loop is added and torque ripple is de ned as an objective function. By using fuzzy sliding mode strategy, the DC...

Recently, the population of Yangtze finless porpoise has been declining. Dredging in Poyang Lake might possibly influence the acoustic environment of the porpoise which relies on echolocation for communication and detection of their prey. A better insight in the spatial distribution of dredging related noise would be useful to assess possible impacts. Traditional in situ measurements of hydro a...

This paper presents a hands-free speech recognition method based on HMM composition and separation for speech contaminated not only by additive noise but also by an acoustic transfer function. The method realizes an improved user interface such that a user is not encumbered by microphone equipment in noisy and reverberant environments. The use of HMM composition has already been proposed for co...

Understanding combustion noise source mechanisms, designing efficient acoustic liners and optimising active control algorithms for noise reduction requires the identification of the frequency and modal content of the combustion noise contribution. Coherence-based noise source identification techniques have been developed which can be used to identify the contribution of combustion noise to near...

Cooling fans are used to solve the thermal problems of most critical electronic parts in systems. Therefore, it is very important to monitor the fans condition periodically dealing with the detection, location and analysis of the possible faults. The fault diagnosis of rotating systems is increasingly paying attention. The main purpose of this study is to investigate the possible faults in a ro...