This paper introduces a novel probabilistic method for robot based object segmentation. The method integrates knowledge of the robot's motion to determine the shape and location of objects. This allows a robot with no prior knowledge of its workspace to isolate objects against their surroundings by moving them and observing their visual feedback. The main contribution of the paper is to improve upon current methods by allowing object segmentation in changing environments and moving backgrounds. The approach allows optimal values for the algorithm parameters to be estimated. Empirical studies against alternatives demonstrate clear improvements in both planar and three dimensional motion.
The Boltimann equation for electrons is analyzed for a low-pressure inductively coupled rf discharge in argon driven by a planar-coil. Spatially resolved probe measurements of the electron distribution function (EDF) indicate that the total energy of electrons is an argument of the EDF. Pressure dependence of the light emission distribution is explained on the basis of nonlocal electron kinetics. -Inductively coupled rf discharges are currently being investigated as plasma sources for material processing.' For the pressure range of interest, l-100 mTorr, the electron energy relaxation length exceeds the characteristic discharge dimensions (of the order of 10 cm) and the electron distribution function' (EDF) is not in equilibrium with the local electric field (see for example Ref. 3 and references therein). In such a nonlocal regime, a kinetic treatment of electrons is necessary to calculate the ionization rate, plasma density, electron current density, etc. In this letter we analyze the main consequences of nonlocal electron kinetics by examining the Boltzmann equation for a given spatial distribution of electric fields (both electrostatic and rf fields) to explain experimental data for a planar inductively coupled discharge in argon. The discharge's most distinguishing feature appears in the spatial separation of electron heating and ionization. Though the electron heating occurs in the region of a high rf field, a substantial portion of ionization is produced near the maximum of the electrostatic potential where the rf field is absent.The discharge is driven by the electric field from a spiral coil placed on the dielectric roof of a squat cylinder with metallic walls and bottom (Fig. 1). The azimuthal r-f field EB is localized in the vicinity of the antenna and peaks in an annular region at roughly half of the chamber radius. The electron heating mechanism depends on the relative magnitude of the three characteristic dimensions: field penetration depth S, electron mean-free path h, and the length V/W which electron passes during the field period." When X is the smallest of them, the ohmic heating take place, when the smallest is 6, the collisionless heating is expected to occur.5Since the electron energy relaxation length exceeds the spatial scale, the total energy E=W -e +(z,r) is the argument of the EDE6-* The observed profile of the electrostatic potential &,r) is shown schematically in Fig. 2. Curves 1 and 2 correspond to axial distribution of &z,r) at r =0 and at the point r-a, where the maximal amplitude of the rf field is reached. The potential of the metallic wall rl with respect to the plasma exceeds the excitation potential E*. The dashed area indicates the region in (~,z,r) space where inelastic collisions occur. The electrons with E>E* have a kinetic energy M, sufficient for excitation only in a region slightly above curve 3, where their potential energy is approximately zero.We will consider here the case of small anisotropy of the EDF when the conventional two-term approximation is applicable f=f...
Quadrics are a compact mathematical formulation for a range of primitive surfaces. A problem arises when there are not enough data points to compute the model but knowledge of the shape is available. This paper presents a method for fitting a quadric with a Bayesian prior. We use a matrix normal prior in order to favour ellipsoids when fitting to ambiguous data. The results show the algorithm copes well when there are few points in the point cloud, competing with contemporary techniques in the area.
Time-resolved measurements of ion energy distributions and optical emissions in pulsed radio-frequency discharges
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