PubMed · 15977951
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Paul Robbins. 2005. Managing risk in device engineering.. https://pubmed.ncbi.nlm.nih.gov/15977951/
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The present paper addresses the numerical optimization of geometrical parameters of non-Newtonian micro-scale viscous pumps for biomedical devices. The objective is to maximize the mass flow rate per unit of shaft power consumed by the rotor when an external pressure load is applied along the channel that houses the rotor. Two geometric parameters are considered in the optimization process: (i) the height of the channel that houses the rotor (H) and (ii), the eccentricity (epsilon) of the rotor. Three different micro-scale viscous pump configurations were tested: a straight-housed pump (I-shaped housing) and two curved housed pumps (L- and U-shaped housings). The stress-strain constitutive law is modeled by a power-law relation. The results show that the geometric optimization of micro-scale viscous pumps is critical since the mass flow rate propelled by the rotor is highly dependent on epsilon and H. Numerical simulations indicate that mass flow rate is maximized when epsilon approximately 0, namely when the rotor is placed at a distance of 0.05 radii from the lower wall. The results also show that micro-scale viscous pumps with curved housing provide higher mass flow rate per unit of shaft power consumed when compared with straight-housed pumps. The results are presented in terms optimized dimensions of all three configurations (i.e., H(opt) and epsilon(opt)) and for values of the power-law index varying between 0.5 (shear thinning fluids) and 1.5 (shear-thickening fluids).
A pulsed laser diode system operating at 905 nm has been developed for the generation of photoacoustic signals in tissue. It was evaluated by measuring the photoacoustic waveforms generated in a blood vessel phantom comprising three dye-filled (mu(a)=1 mm(-1)) tubes of diameters 120-580 microm immersed to a maximum depth of 9 mm in a turbid liquid (mu'(s)=1 mm(-1)). The system was then combined with a cylindrical scanning system to obtain two-dimensional images of a tissue phantom. The signal-to-noise ratio of the detected signals in both cases and the image contrast in the latter suggest that such a system could provide a compact and inexpensive alternative to current excitation sources for superficial imaging applications.
The combination of web technology, knowledge of bioprocess engineering, and theories on learning and instruction might yield innovative learning material for bioprocess engineering. In this article, an overview of the characteristics of web-based learning material is given, as well as guidelines for the design of learning material from theories of learning and instruction and from the bioprocess engineering domain. A diverse body of learning material is presented, which illustrates the application of these guidelines; this material has been developed during the past six years for different courses, mostly at undergraduate level, and it illustrates how web-based learning material can enable various different approaches to learning objectives that might improve overall learning. Such learning material has been used for several years in education, it has been evaluated with positive results, and is now part of the regular learning material for bioprocess engineering at Wageningen University.