A fundamental group for greyscale digital images

One of the concepts from topology that has found use in image processing is the so called Fundamental Group of an image. A definition for the digital fundamental group of a binary picture was introduced by Kong in A digital fundamental group [4]. This paper introduces a fundamental group for greyscale images. We also describe Poincaré's classical method for computing a representation of the fundamental group and extend this to work with our greyscale version.     

Demonstration of GaN MIS diodes by using AlN and Ga2O3(Gd2O3) as dielectrics

GaN MIS diodes were demonstrated utilizing AlN and Ga₂O₃(Gd₂O₃) as insulators. A 345 Å of AlN was grown on the MOCVD grown n-GaN in a MOMBE system using trimethylamine alane as Al precursor and nitrogen generated from a SVT RF N₂ plasma. For the Ga₂O₃(Gd₂O₃) growth, a multi-MBE chamber was used and a 195 Å oxide was E-beam evaporated from a single crystal source of Ga₅Gd₃O₁₂. The forward breakdown voltage of AlN and Ga₂O₃(Gd₂O₃) diodes are 5 and 6 V, respectively, which are significantly improved over 1.2 V from that of a Schottky contact. From the C–V measurements, both kinds of diodes showed good charge modulation from accumulation to depletion at different frequencies. The insulator/GaN interface roughness and the thickness of the insulator were measured with X-ray reflectivity.     

Evidence of limited capacity and noise reduction with single-element displays in the location-cuing paradigm.

Precuing a location facilitates accuracy of identification of a target at that location and reduces noise from other nontarget characters in a multicharacter field. In 5 experiments, evidence for facilitation included higher accuracy with long precue–target intervals than with short intervals and higher accuracy when a precue indicated the correct location than when it indicated the wrong location. These results were found for each target–mask condition used (1 target with 1 mask, 1 target with 4 masks, or 1 target and 3 nontargets with 4 masks) in experienced and inexperienced observers. Evidence for noise reduction was found because accuracy was higher in the 1 target–1 mask condition than in the other conditions on correctly cued trials with short cue–target intervals and on incorrectly cued trials. Data are related to methodological factors that are important to obtaining these effects and to capacity and noise reduction models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The thermal effect in the photomechanical conversion of a photochromic polymer

Summary The effect of radiation on the mechanical behaviour of the crosslinked copolymer of maleic anhydride and styrene containing photochromic azo groups was investigated. The analysis of results of the observed photomechanical conversion proved a considerable influence of the thermal effect in addition to the effect of photoisomerization of the photochrome. The interpretation of some photomechanical experiments described earlier may be obscured by a rise in temperature caused by the absorption of radiation.     

Silicon fabricated submicrometer stepper motor for microsurgicalprocedures

A linear stepper motor has been constructed with submicrometer step size and centimeter travel range. Silicon wafers with conventional dielectrics provide a basic electrostatic clamping mechanism, while a piezoelectric material serves as an electrical-to-mechanical power transducer. Movement is generated by using the inertial properties of an attached mass coupled with fast and slow expansions and contractions of the piezoelectric material. The fast transitions use the inertia of the mass to move the clamp, while the slow transitions move the mass while keeping the clamp fixed. Five prototype hand-held stepper motors have been successfully built and tested. The components of the motor fit within a pen-sized cylindrical stainless steel shell (15 cm × 1.2 cm) and deliver a displacement of 38 mm. For the given operating conditions, the tested handpieces had 1.2 mm/s advancement speeds against a 3 N load. The electrostatic clamp generates an attraction force of about 2 N using a clamp with an area of 3.75 cm² and 150 V across the faces. Maximum step sizes for the piezoelectric transducer (PZT) used here are slightly less than 10 μm, and steps less than 100 nm can be obtained with sufficiently low PZT voltages. Motor speed can be controlled by adjusting the operating frequency