An active vibration control system has been developed based upon analogue feedback and optical vibration sensing. ZnO thin films have been deposited using r.f. magnetron sputtering onto silicon substrates and cantilevers fabricated using photolithography. These cantilevers provide a means of actuation and micro-positioning. The system operates such that unwanted vibrations in the cantilever are removed and yet it remains possible to deflect the cantilever statically or dynamically as required. Results are presented for such a system.

Piezoelectric elements as actuators have been extensively used to control struictures with a wide range of sizes. The effect of piezo-actuator thickness on the magnitude of deflection of a cantilever beam has been investigated experimentally and the results compared with a theoretical model. Results indicate that there exists a piezo-actuator thickness which maximises the cantilever deflection, and this optimal thickness is a function of the ratio of the Young's modulus of the actuator and the cantilever. The significance for actuator design is discussed.

House dust mites are found in almost all dwellings in New Zealand and are a major risk factor in the development of asthma and perennial allergic rhinitis. We studied the longevity, life stage length, and fecundity of a New Zealand strain of European house dust mite, Dermatophagoides pteronyssinus (Trouessart), at constant (23 degrees C, 75% RH) and the fluctuating conditions typically found in dry (18-25 degrees C, 60-38% RH) and damp (18-23 degrees C, 70-55% RH) New Zealand dust mite microhabitats in carpets. All the adult mites placed in the "dry" conditions died within 18 d. Mites in the "da conditions had developmental times, oviposition, and death rates that were not significantly different from constant conditions. These mites are tolerant of fluctuating temperatures, but they are more susceptible to environments that strongly fluctuate in humidity.

When dealing with thousands of genes, all potentially interesting, it is desirable to rank the genes according to their degree of participation in a physiological process. Therefore, genes with the highest Shannon entropy and ERL can be selected as the best toxicity target candidates, permitting preclinical scientists to focus their research and resources on those genes.

A major challenge in the field of functional genomics is the development of computational techniques for organizing and interpreting large amounts of gene expression data. These methods will be critical for the discovery of new therapeutic drug targets. Here, we present a simple method for determining the most likely drug target candidates from temporal gene expression patterns assayed with reverse-transcription polymerase chain reaction (RT-PCR) and DNA microarrays.

Piezoelectric elements may be used as actuators to control a wide range of structures. The magnitude of deflection which is possible for a cantilever is a direct function of the ratio of the thickness of the piezoelectric element to that of the cantilever. An experimental investigation has been carried out to determine the exact nature of this phenomenon for two materials and the results compared with current theoretical models. The significance for actuator design is discussed.

There is currently considerable interest in the development of piezoelectric materials with properties that cannot at present be attained with single-phase materials. Composite piezoelectric thick films have been prepared and characterized. These films, deposited directly onto metallized glass cantilevers, have been shown to be effective as micro-actuators.

Piezoelectric thin films of PZT have been deposited using r.f. magnetron sputtering onto silicon substrates and cantilevers fabricated using chemical etching and photolithography. These micro-actuators are unobtrusive and are able to work over a wide bandwidth at low voltage. Results are presented for such a system.

Vibration noise reduction has been achieved in non-contact magnetic imaging using magnetic force microscopy by feeding back the inverted noise signal as an electrostatic force between the cantilever and the sample. This simple and low-cost method has been shown to be very effective at improving the imaging performance.

An actuation system is described which utilizes a single active ZnO piezoelectric thin film deposited onto a silicon cantilever. The method for obtaining films for effective actuation by r.f. magnetron sputtering is discussed. The actuator has been incorporated into a system which enables unwanted vibrations of the cantilever to be cancelled, whilst maintaining the ability simultaneously to deflect the cantilever as required.

AbstractAn active vibration control system has been developed based upon analogue feedback and optical vibration sensing. Composite piezoelectric films have been deposited directly onto the cantilever to provide a means of actuation and micro‐positioning. The system operates such that unwanted vibrations in the cantilever are removed and yet it remains possible to deflect the cantilever statically or dynamically as required. Results are presented for such a system.

The study of free vibrations of systems such as simple cantilevers has been mainly concerned with the determination of the eigenvalues (frequencies) and eigenfunctions (modal shapes). A technique has been developed, using optical beam deflection, to measure the modal shape of a cantilever non-invasively at each modal frequency. A knowledge of the modal shapes of very small cantilevers incorporating suitable actuators is important in the application of active vibration control to micromechanical structures.

This paper describes the design of an involute spur gear inspection system in which measurements are made using a video camera and image analysis software. The measurement accuracy possible using low-cost CCTV cameras is investigated, and the possible sources of error identified. It is concluded that the measurement accuracy is comparable to that of current methods for tolerance inspection of spur gears and the low cost and ease of use make image analysis measurement systems an attractive alternative.

A control and actuation system is described which utilises a single active piezoelectric composite thick film and optical vibration sensing. This system enables unwanted vibrations of the cantilever to be cancelled, whilst maintaining the ability to deflect the cantilever statically or dynamically as required. The use of such piezoelectric elements in scanning probe microscopes is duscussed.

The deflection control of a small cantilever is described, which operates using a single active piezoelectric element and optical vibration sensing, so that unwanted vibrations in the cantilever are removed, and yet it remains possible to deflect the cantilever statically or dynamically as required. Such a control system is directly applicable to the very small cantilevers found in scanning probe microscopes, such as atomic force and magnetic force microscopes, the resolution of which is limited by unwanted vibration.

A magnetic force instrument is described which makes use of a differential interferometer which can be used with a very short length cantilever in the force detection assembly. Conventional methods work with cantilevers of a few millimetres in length, but are not suitable for the very much smaller commercial cantilevers which are now available. The instrument described contains novel features which enable it to be used with such cantilevers. Topographical images of calibration specimens and magnetic images of hard disk samples obtained using this instrument are presented.

The design and application of scanning probe microscope primarily intended for topographic, magnetic force and magneto-optical investigations of magnetic thin films is described. A microfabricated silicon tip is scanned across the sample of interest, and the tip deflection detected using a modified form of the den Boef twin beam interferometric system. Initial studies of the recorded bit structure in magnetic and magneto-optic storage media, and the magnetic field from a thin film recording head are reported.

Using multiple endonuclease restriction enzymes it was possible to distinguish 31 patterns among 33 epidemiologically independent Candida albicans from the oral cavity. This degree of discrimination required the use of three restriction enzymes.