Embedded micromachined fiber-optic Fabry-Perot pressure sensors in aerodynamics applications

Small size, high bandwidth pressure sensors are required for instrumentation of probes and test models in aerodynamic studies of complex unsteady flows. Optical-fiber pressure sensors promise potential advantages of small size and low cost in comparison with their electrical counterparts. We describe miniature Fabry-Perot cavity pressure sensors constructed by micromachining techniques in a turbine test application. The sensor bodies are 500 /spl mu/m squared, 300 /spl mu/m deep with a /spl sim/2 /spl mu/m-thick copper diaphragm electroplated on one face. The sensor cavity is formed between the diaphragm and the cleaved end of a single mode fiber sealed to the sensor by epoxy. Each sensor is addressed interferometrically in reflection by three wavelengths simultaneously, giving an unambiguous phase determination; a pressure sensitivity of 1.6 radbar/sup -1/ was measured, with a typical range of vacuum to 600 kPa. Five sensors were embedded in the trailing edge of a nozzle guide vane installed upstream of a rotor in a full-scale turbine stage transient test facility. Pressure signals in the trailing edge flow show marked structure at the 8 kHz blade passing frequency. To our knowledge, this is the first report of sensors located at the trailing edge of a normal-sized turbine blade.     

Real-time contactless measurement of robot pose in six degrees of freedom

For dynamically measuring position in three degrees of freedom laser tracking systems are well known. Up to now no possibility to measure also orientation using the same laser beam has been known. We present a technique to incorporate orientation measurement into a laser tracking system that requires only minor changes in the existing hardware. The method is based on the analysis of an image of the reflected laser beam intensity distribution. In this image the edges of a slightly modified retroreflector represent a function of the orientation of the end-effector holding the retroreflector. It is shown that from this image the orientation can be determined uniquely and in real time.

A laser tracking system including position and orientation measurement constitutes an instrument to accurately determine robot performance as well as to acquire hints on how to improve robot models and control algorithms.     

Margarine oils,shortenings, and vanaspati

The technology of processes aimed at the production of margarine has, on the whole, not changed dramatically during the past 20 years. However, a great number of technological modifications for quality improvement and adaption to market requirements have been achieved. These include tailor-made refining procedures for more flexible blend formulations, careful exclusion of oxygen in closed systems (for refining, dosing, emulsification, and cooling), and development of soft margarine, rich in linoleic acid and mostly packed in tubs. The processing of margarine is fully mechanized today and might be partly automated in the future. As for vanaspati, there have been hardly any changes on the processing side, which includes a slow crystallization phase that hardly lends itself to mechanization and automation. Like margarine, more flexible blend formulations have been made available, and improvements in flavor technology have been achieved. Shortening development has run completely parallel to margarine development.     

Utilization of phosphocholine from extracellular complex polysaccharide as a source of cytoplasmic choline derivatives in Penicillium fellutanum

Penicillium fellutanum produces a phosphorylated, choline-containing extracellular polysaccharide, peptidophosphogalactomannan (pP(x)GM) [where x is the number of phosphodiester residues]). The 13C-methyl-labeled pP(x)GM ([methyl-13C]pP(x)GM) was prepared from the cultures supplemented with L-[methyl-13C]methionine and was used as a probe to monitor the fate of phosphocholine in this polymer. The addition of [methyl-13C]pP(x)GM to growing cultures in low-phosphate medium resulted in the disappearance within 5 days of [methyl-13C]phosphocholine and N,N'-dimethylphosphoethanolamine from the added [methyl-13C]pP(x)GM. Two 13C-methyl-enriched cytoplasmic solutes, choline-O-sulfate and glycine betaine, were found in mycelial extracts, suggesting that phosphocholine-containing extracellular pP(x)GM of P. fellutanum is a precursor of intracellular choline-O-sulfate and glycine betaine. The mycelia cultured in low-phosphate (2 mM) medium contained glycine betaine and 1.5-fold more choline-O-sulfate than those grown in high-phosphate (20 mM) medium. The high levels of extracellular nonspecific phosphocholine:phosphocholine hydrolase and acid phosphomonoesterase observed in the low-phosphate culture medium are likely related to the release of phosphocholine from pP(x)GM and hydrolysis of phosphocholine, respectively. These results suggest that extracellular pP(x)GM of P. fellutanum provides phosphate needed as the environment becomes depleted of this nutrient. Choline, in excess of that needed immediately, is stored in the cytoplasm in forms that can be reutilized.     

Improving stability and release kinetics of microencapsulated tetanus toxoid by co-encapsulation of additives

PURPOSE: Tetanus toxoid (Ttxd) encapsulated in polyester microspheres (MS) for single injection immunization have so far given pulsatile in vitro release and strong immune response in animals, but no boosting effect. This has been ascribed to insufficient toxoid stability within the MS exposed to in vivo conditions over a prolonged time period. This study examined the effect of co-encapsulated putative stabilizing additives. METHODS: Two different Ttxd were encapsulated in poly(D,L-lactic-co-glycolic acid) (PLGA 50:50) and poly(D,L-lactic acid) (PLA) MS by spray-drying. The influence of co-encapsulated additives on toxoid stability, loading in and release from the MS, was studied by fluorimetry and ELISA. RESULTS: Co-encapsulated albumin, trehalose and gamma-hydroxypropyl cyclodextrin all improved the toxoid encapsulation efficiency in PLGA 50:50 MS. Albumin increased the encapsulation efficiency of antigenic Ttxd by one to two orders of magnitude. Further, with albumin or a mixture of albumin and trehalose ELISA responsive Ttxd was released over 1-2 months following a pulsatile pattern. CONCLUSIONS: Optimized Ttxd containing MS may be valuable for a single-dose vaccine delivery system.     

Flaring dies to suppress die drool

Die lip build‐up is the unwanted material accumulation on extrusion die lips. Here, flared dies are shown experimentally to suppress die lip build‐up. A semiempirical method for flared die design is also provided. Nonlinear viscoelastic constitutive equations are used to calculate the wall shear stress and first normal stress difference in flared dies. By incorporating melt memory, a promising design method for die flaring is presented. The stress history upstream of the die exit governs the die design. The upstream gap is selected to maximize undershoot of the first normal stress difference N₁ at the die wall caused by flaring. The flare length, on the other hand, is selected to ensure a steady N₁ at the die lips.     

Solving nonlinear eigenvalue problems by algorithmic differentiation

The eigenvalues of a matrixA(λ), the elements of which are complex functions of a complex variable λ, can be found with a zero finding method applied to the determinant function detA(λ). It is proposed to evaluate the derivatives of det (λ) used in the zero finding method by algorithmic differentiation. This leads to a simple and lucid algorithm. Program listings and numerical examples are given.