A bin picking system based on depth from defocus

It is generally accepted that to develop versatile bin-picking systems capable of grasping and manipulation operations, accurate 3-D information is required. To accomplish this goal, we have developed a fast and precise range sensor based on active depth from defocus (DFD). This sensor is used in conjunction with a three-component vision system, which is able to recognize and evaluate the attitude of 3-D objects. The first component performs scene segmentation using an edge-based approach. Since edges are used to detect the object boundaries, a key issue consists of improving the quality of edge detection. The second component attempts to recognize the object placed on the top of the object pile using a model-driven approach in which the segmented surfaces are compared with those stored in the model database. Finally, the attitude of the recognized object is evaluated using an eigenimage approach augmented with range data analysis. The full bin-picking system will be outlined, and a number of experimental results will be examined. Received: 2 December 2000 / Accepted: 9 September 2001 Correspondence to: O. Ghita     

Monitoring the effects of selective laser sintering (SLS) build parameters on polyamide using near infrared spectroscopy

Near infrared spectroscopy has been used to monitor the effects of changing build parameters on the sintering process of selective laser sintering components. The surface roughness of the parts produced has been studied whilst modifying laser scan speed and laser power build parameters. Near infrared spectroscopy is shown to be a powerful tool in detecting subtle variations in the coalescence of particles that form the surface topology of the component. Principal component analysis (PCA) performed on the diffuse reflectance spectra obtained from the surface of the components shows a strong correlation between near infrared (NIR) spectra and build parameters. Using the chemometric model produced from the PCA analysis it is possible to calculate build parameters for unknown components, making NIR a useful aid for quality control of additive manufacturing technologies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Successful closed-loop recycling of thermoset composites

This study investigates closed-loop thermoset composite recycling through grinding and reincorporation. Contrary to many other studies, it is shown that by careful attention to the separation and reformulation procedure, the mechanical integrity of recycled composites can be improved, and the use of substantially larger volumes of recyclate is possible. Both factors are important aspects affecting the economic viability of regrinding as a possible future solution to the composites recycling problem.     

Electrochemically modulated liquid-liquid extraction of ions

The development of ion extraction methods under electrochemical control via electrochemistry at the interface between two immiscible electrolyte solutions is discussed. A hydrodynamic flow injection system was used for the potentiostatic extraction of non-redox-active species from a flowing aqueous phase into a stationary organogel phase. The ions tetraethylammonium, 4-octylbenzenesulfonate (4-OBSA-), and p-toluenesulfonate (p-TSA-) were studied as model analytes. The extraction study comprised examination of the influence of extraction potentials, aqueous-phase flow rate, and target species concentration. The extraction process can be monitored in situ by means of the ion-transfer current, which has opposing signs for anions and cations. Hydrodynamic voltammograms were obtained from these experiments. The selective extraction of 4-OBSA-, from its mixture with p-TSA-, as well as coextraction of both anions is shown. The results demonstrate the utility of electrochemical modulation for the controlled extraction of ions from an aqueous phase into an organogel electrolyte phase. This offers potential benefits for various analytical processes including sample preparation and cleanup.     

A method for analysis and profiling of boron,carbon and oxygen impurities in semiconductor wafers by recoil atoms in heavy ion beams

A method based on identification of recoil atoms in heavy ion beams, by using a (ΔE, E) measuring system, is described. The two parameter (ΔE, E) spectra, obtained with the aid of a computer, shows a good separation between carbon and oxygen recoils originating from a 300 μ;m thick silicon wafer bombarded with a 70 MeV sulphur beam. Profiling depths 10–20 μm and sensitivities close to 10¹⁶ atoms/cm are estimated.