Although coordinate metrology has reached a very high state of development concerning versatility and accuracy for
common engineering parts, a high precision capability with nano scale resolution and accuracy is often hard to achieve
when it is required to measure very small parts and features. The limiting component is the bulky probing system of
traditional coordinate measuring machines (CMMs). In order to satisfy increasing demand for highly accurate
geometrical measurements on small parts and small structures, a new measuring probe of high sensitivity and small
geometrical dimension with low contact forces needs to be developed. In this paper, a probing system, which combines a
Fibre Bragg grating (FBG) embedded optical fibre tactile probe with an optical sensing technique, has been used. A
novel simple wavelength shift demodulation system is tested which incorporates using the single mode light launched
from a laser diode (LD) forming an external cavity between the LD and the FBG sensor to detect the Bragg wavelength
shift induced by the strain on the FBG sensor. This demodulation method can be used to detect the strain-induced
wavelength shift of the FBG. A strain resolution of 0.6 με is achieved. With the sensor elements integrated into the probe
tip directly, the system sensitivity can be increased significantly.
The first continuous flow micro PCR introduced in 1998 has attracted considerable attention for the past several years
because of its ability to amplify DNA at much faster rate than the conventional PCR and micro chamber PCR method.
The amplification is obtained by moving the sample through 3 different fixed temperature zones. In this paper, the
thermal behavior of a continuous flow PCR chip is studied using commercially available finite element software. We
study the temperature uniformity and temperature gradient on the chip's top surface, the cover plate and the interface of
the two layers. The material for the chip body and cover plate is glass. The duration for the PCR chip to achieve
equilibrium temperature is also studied.
With the reduction in dimensions of products in the last decade, the need for highly accurate dimensional inspection and measurement increases, which requires down scaled measuring tools. The key element for a powerful down scaled dimensional measuring tool coordinate measuring machine is the downscaled probe. In order to satisfy the ongoing increasing demand for highly accurate geometrical measurements on small parts and small structures, a new measuring probe having high sensitivity and small geometrical dimension with low contact forces needs to be developed. In this paper, a novel probing system, which combines a FBG (Fibre Bragg Grating) embedded optical fibre tactile probe with an optical sensing technique, is proposed for down scaled 3D micro-CMMs. The Bragg wavelength shifts with the strain developed along the fibre once the fibre touches the surface of the part. With high-resolution interferometric wavelength demodulation technology, a resolution of 5nm could be achieved by the FBG integrated system. With the sensor elements integrated into the probe tip directly, the system sensitivity can be increased significantly for 3 dimensional measurements.
The wide utilisation of micro-systems has brought increasing attention into micro-fluidics in recent years. When the size and mass of a device are scaled down, forces which used to be ignored may become dominant in the performance of a micro system. This paper studies the behaviour of fluid responding to travelling sinusoidal waves imposed by a micro actuator. The thickness of the fluid between the wave surface and the substrate is 20 microns, and the wavelength is 50 microns. The model is developed and implemented in ANSYS. The nonlinearities of the flow exist in both <i>X</i> and <i>Y</i> directions. A stable thrust force can be generated by the moving waves. The direction of the thrust force is opposite to the direction of the travelling wave. The magnitude of the thrust force is related to fluid viscosity, wave amplitude, and wave frequency. As this force is highly predictable and controllable, it can be used to propel a micro device working in thin tubes filled with fluid. The principle could also be applied to non-Newtonian fluid, although the flow will be more complicate.
This paper presents a novel ultrasonic transducer which can be used as a liquid ejector to release drug. The ultrasonic transducer is based on the design of a flextensional transducer, which is composed of interdigital piezoelectric rings and a vibration membrane. The device works at an axisymmetric resonant mode to produce maximum amplitude at the center of the vibration membrane in axial direction. For the usage of multi piezoelectric rings, the flexural plate waves can be generated by applying two out-of-phase signals. The power consumption is of primary importance in the design of this device and the usage of single-ring or multi-ring piezoelectric material instead of bulk piezo material can therefore reduce the power consumption. An optimum working frequency, at which least power is required by the device, can be found by the piezoelectric, coupled field capability of the ANSYS/Multiphysics product.
In the last decade the general miniaturisation of complex products has lead to an increased importance of high precision machining and assembly. Together with increasing precision of products, the need for highly accurate dimensional inspection increases. CMMs (Coordinate Measuring Machines), as a versatile and widespread dimensional metrology tool, can efficiently perform complex measurement with a resolution of about 0.1μm and a repeatability of about 0.3μm. The existing probes for CMMs tend to be very bulky and result in high probing forces for geometrical measurements of high accuracy on small parts. In this paper, an economical flexible method, which is based on optical fibre splicer, is proposed to fabricate an integrated micro scale silicon probe with spherical tip for micron CMMs. Based on Taguchi method, a combination of optimised process parameters has been obtained to control the fabrication conditions that will ensure the manufacturing of tips of a high and consistent quality. With proper control of the process parameters, an optic fibre probe tip with the diameter dimension in the range of 200 to 400μm is achieved and there is a great potential to fabricate a smaller tip with a diameter of 50-100μm in the future.
Although coordinate metrology has reached a very high state of development concerning versatility and accuracy for common engineering parts, a high precision capability with nano scale resolution and accuracy is often hard to achieve when it is required to measure very small parts and features. The limiting component is the bulky probing system of traditional CMMs (coordinate measuring machines). In order to satisfy increasing demand for highly accurate geometrical measurements on small parts and small structures, a new measuring probe of high sensitivity and small geometrical dimension with low contact forces needs to be developed. In this paper, a novel probing system, which combines a FBG (Fibre Bragg Grating) embedded optical fibre tactile probe with an optical sensing technique, has been proposed. With the sensor elements integrated into the probe tip directly, the system sensitivity can be increased significantly. A preliminary theoretical analysis of the sensitivity of the FBG fibre sensor under axial and lateral end point loading has been presented and the results show that this micro scale probe has great potential to realize a resolution of 1nanometer on geometrical measurement of small parts.
Fiber identification has been a very important task in many industries such as wool growing, textile processing, archaeology, histochernical engineering, and zoology. Over the years, animal fibers have been identified using physical and chemical approaches. Recently, objective identification of animal fibers has been developed based on the cuticular information of fibers. Effective and accurate extraction of representative features is essential to animal fiber identification and classification. In the current work, two different strategies are developed for this purpose. In the first method, explicit features are extracted using image processing. However, only implicit features are used in the second method with an unsupervised artificial neural network. It is found that the use of explicit features increases the accuracy of fiber identification but requires more effort on processing images and solid knowledge of what features are representative ones.
Image processing and pattern recognition have been successfully applied in many textile related areas. For example, they have been used in defect detection of cotton fibers and various fabrics. In this work, the application of image processing into animal fiber classification is discussed. Integrated into/with artificial neural networks, the image processing technique has provided a useful tool to solve complex problems in textile technology. Three different approaches are used in this work for fiber classification and pattern recognition: feature extraction with image process, pattern recognition and classification with artificial neural networks, and feature recognition and classification with artificial neural network. All of them yields satisfactory results by giving a high level of accuracy in classification.
Industrial application of infrared thermography is virtually boundless as it can be used in any situations where there are temperature differences. This technology has particularly been widely used in automotive industry for process evaluation and system design. In this work, thermal image processing technique will be introduced to quantitatively calculate the heat stored in a warm/hot object and consequently, a thermal control system will be proposed to accurately and actively manage the thermal distribution within the object in accordance with the heat calculated from the thermal images.
In this article, the basic principle and the key technique of an optoelectronic type of electric current transducer system are discussed. The system is used to measure the primary current in a high-voltage and large-capacity power system.It has many advantages such as wide current range, high precision, simple insulation structure and high price- performance ratio. The signals of electric current at the high-voltage side are converted to digital signals, which are coded according to a special mode and transmitted with a special baud rate. In order to ensure the measuring accuracy, a fast quasi-synchronous weighting algorithm is adopted to do data processing at the low-voltage side.