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As technology improves human vision, some procedures currently performed may be causing a decrease of the natural UV protection of the cornea. A portable dual beam system prototype was assembled for physicians for clinical studies of these effects on the corneas endowing two types of 300-400 nm evaluations: 1, regularly donated corneas and 2, simulating refractive keratectomy by corneal lamellae removal. The system performs 500 measurements/s, providing [+ or -] 0.25% precision for the transmittance. The measurements performed on the prototype are 95% in agreement with Cary 17 and HR4000CG-UVNIR Ocean Optics spectrophotometers. Preliminary studies on cadaveric corneas demonstrate that, as the stromal layer is reduced (~ 150 [micro]m depth), there is significant loss--an average of 7.1%.--of the cornea's natural UV protection. The prototype is being tested in an eye bank for routine evaluation of donor corneas. OCIS codes: 170.0170, 330.5380, 300.6540.

Problem statement: A successful operation of rapid prototyping process depends on software and hardware which are used in RP machines. About software, an efficient technique is required to slice the CAD model. Several slicing methods are used for slicing from Standard Triangulation Language (STL) files, such as direct slicing and adaptive slicing. Using these methods reduce accuracy of physical part or increase process time. About hardware, in Stereolithography (SLA) apparatus, two mirrors have been used to reflect laser beam. Approach: In this study new algorithms were developed for part slicing from STL file and modifying the laser beam path such as: Derivation of contours in each layer, generate contour family tree, detective arcs and modifying laser beam path. A modified mechanism was designed and developed based on only one mirror to reflect laser beam. Results: These algorithms were used in a visual basic interface and the developed mechanism was implemented in a prototype apparatus. Conclusion: Developed algorithms decreased CAD model slicing time and generated more accurate laser beam path than usual methods and fabricated apparatus decreased scanning mechanism complexity and volume of the scanning system. Key words: Rapid prototyping, STL format, contour, INTRODUCTION Rapid Prototyping (RP) produces a physical prototype from a CAD model by building a part layer by layer in shorter time than more traditional prototyping methods. Unlike the traditional [...]

Paraffin wax is a promising material in microactuators not only because of its ability of producing large displacements and high forces at the same time but also because of the variety of manufacturing techniques available. In this paper, a simple actuator based on paraffin wax as the active material is fabricated and tested. Ultraviolet-curable epoxy is used in a technique combining simultaneous moulding and liquid-phase photopolymerization in a single-process step to build the stiff part of the actuator body. A heater is integrated in the paraffin reservoir, and a polyimide tape is used as the deflecting membrane. Thermomechanlcal analysis of the paraffin wax shows that it exhibits a volume expansion of 10%, including phase transitions and linear expansion. As for the actuator, a stroke of 90 pm is obtained for the unloaded device, whereas 37/[micro]m is recorded with a 0.5-N contact load at a driving voltage of 0.71 V and a frequency of 1/32 Hz. The actuator can be used in microsystems, where both large strokes and forces are needed. The low-cost materials and low driving voltage also makes it suitable for disposable systems. [2008-0024] Index Terms--Actuator, paraffin wax, rapid prototyping.

The studies reported here examined differences in user behaviour when presented with a low-fidelity paper prototype compared to fully operational product, and evaluated the effectiveness of different types of enhanced labelling of controls. In the first study with a paper prototype, 30 users of high-pressure washers were asked to choose the settings of the temperature control for different cleaning objects, comparing standard with information-enriched control labelling. In the second study, 34 users operated a real high-pressure washer with different forms of control labelling. The results of both studies provided evidence for some benefits of an information-enriched control labelling over traditional temperature-centred controls labelling. Furthermore, a comparative analysis of the data of the two studies suggested that low-fidelity paper prototypes may have to be used with caution. Therefore, designers need to be aware that the behavioural effects induced by different design modifications may be overestimated when using paper prototypes. The implications of the findings are discussed within the framework of an enlarged concept of fidelity. Keywords: Paper prototype; Simulation fidelity; Consumer product

The filter prototype of side-coupled coaxial filters, which we recently proposed, has been modified to suit an arrangement in which the coupling apertures are placed on the side opposite the coaxial end gaps. In this situation, the modified prototype fits the physical counterpart better, resulting in a further design simplification. In addition, the feeds have also been modeled and included into the prototype, thus enhancing the correspondence between the prototype and physical structure. A practical design, concerning a WIMAX application, shows the reliability of this solution. Index Terms--Coaxial filters, prototype.

This article will give a brief review of the start-of-the-art in commercial practice and advanced research in the field of Rapid Prototyping with special attention to the additive methods of Solid Free Form Fabrication. Recent applications of this technology in computer integrated manufacturing environments will be outlined. Future applications and research in new materials will also be addressed.

Laser machining has been shown to offer an increasingly attractive alternative to net shape forming processes and/or diamond grinding for producing components of advanced ceramic and ceramic composite materials. The control of machine parameters (incident power, feed, beam polarization, position of the focal plane and orientation of the beam relative to the surface) necessary for the optimization of process parameters (material removal rate and arithmetic average surface roughness) and of mechanical properties will be discussed. It will then be shown how these parameters can be incorporated into the operation of a prototype, fully automated, five axis, closed loop controlled laser shaping system (comprising a beam conditioner, high power laser scanner and noncontacting position sensor) to accurately and cost effectively produce complex shapes in advanced ceramic materials.

A general review of Computational Fluid Dynamics (CFD) applications in the automotive industry is presented. CFD has come a long way in influencing the design of automotive components due to continuing advances in computer hardware and software as well as advances in the numerical techniques to solve the equations of fluid flow. The automotive industry's interest in CFD applications stems from its ability to improve automotive design and to reduce product cost and cycle time. We are able to utilize CFD more and more in day-to-day automotive design, and we can expect better conditions for CFD applications in the coming years. CFD applications in the automotive industry are as numerous as are the codes available for the purpose. Applications range from system level (e.g., exterior aerodynamics) to component level (e.g., disk brake cooling). The physics involved cover a wide range of flow regimes (i.e., incompressible, compressible, laminar, turbulent, unsteady, steady, subsonic and transonic flows). Most of the applications fall in the incompressible range and most are turbulent flows. Although most of the flows encountered are unsteady in nature, a majority of them can be approximated as steady cases. The challenge today is to be able to simulate accurately some very complex thermo-fluids phenomena, and to be able to get CFD results fast, in order to effectively apply them in the 'dynamic' design environment of frequent design changes. The key is to utilize CFD in the early design phases so that design changes and fix-ups later are minimized. Proper use of CFD early, helps to significantly reduce prototyping needs and consequently, reduce cost and cycle time.

This paper presents a new digitizing technique which integrates computer vision methods, such as the photometric stereo approach, with the laser displacement sensors (LDS). The curvature at each point of the surface can be measured cost-effectively by the photometric stereo approach. Once the information of curvature of the surface is provided, the measuring speed of LDS can be improved by digitizing at the selected points of the surface and meanwhile the accuracy of digitization is still maintained. By means of the integration, the merits of both approaches can be achieved simultaneously and the efficiency of the digitization can be improved. Experimental results are provided to verify the proposed method.

Trends show that rapid prototyping has led to new fabrication processes that are on the threshold of revolutionizing airframe and component building. Rapid manufacturing allows aerospace companies to eliminate costly tooling and to skip the process of creating metal castings. The use of laser sintering is also discussed.

Rapid prototyping technology is being used by different sectors such as automotive, medical, aerospace, architectural and even by the Federal Bureau of Investigation. The prototypes in this process are created from three dimenional computer aided designs. Rapid prototyping by Objet Geometries, Morris Technologies and Z Corporation are presented.

A new design of high-quality prototype filters for M-band pseudo quadrature mirror filter (QMF) banks uses a method that optimizes a single parameter on a convex error surface. The method provides a good equiripple filter over a long time and minimizes the overlapped passband distortion. Traditional nonlinear optimization cannot be used in designing this method. The filter length does not affect the quality of the solution.

Current plans for space exploration are calling for more information about materials--at ever lower temperatures. The University of Arizona is making a 2-m prototype mirror for the Next Generation Space Telescope (NGST) to operate at 35 K.[1] Previous low temperature measurements of thermal expansion have been limited to temperatures down to 77 K, except for the very low temperature studies of White et al.[2,3,4]

In this paper we propose a new face recognition system based on a biologically inspired filtering method. Our work differs from previous proposals in: 1) the multistage filtering method employed; 2) the pyramid structure used, and most importantly; 3) the prototype construction scheme to determine the models stored in memory. The method is much simpler than previous proposals and relatively inexpensive computationally, while attaining error rates as low as 5%, very close to the best reported results. Index Terms--Adaptative resonance theory, face recognition, image pyramid.