CC-RANSAC: Fitting planes in the presence of multiple surfaces in range data

Range sensors, in particular time-of-flight and stereo cameras, are being increasingly used for applications such as robotics, automotive, human-machine interface and virtual reality. The ability to recover the geometrical structure of visible surfaces is critical for scene understanding. Typical structured indoor or urban scenes are often represented via compositional models comprising multiple planar surface patches. The RANSAC robust regression algorithm is the most popular technique to date for extracting individual planar patches from noisy data sets containing multiple surfaces. Unfortunately, RANSAC fails to produce reliable results in situations with two nearby patches of limited extent, where a single plane crossing through the two patches may contain more inliers than the “correct” models. This is the case of steps, curbs, or ramps, which represent the focus of our research for the impact they can have on cars’ safe parking systems or robot navigation. In an effort to improve the quality of regression in these cases, we propose a modification of the RANSAC algorithm, dubbed CC-RANSAC, that only considers the largest connected components of inliers to evaluate the fitness of a candidate plane. We provide experimental evidence that CC-RANSAC may recover the planar patches composing a typical step or ramp with substantially higher accuracy than the traditional RANSAC algorithm.     

Radiochemical study of the radical copolymerization of styrene and methyl methacrylate

The rates of initiation for the copolymerization of styrene and methyl methacrylate at 50°, in different reaction media (bulk, acetone, dimethylformamide and dioxane) have been determined by using the isotopic labelling technique (¹⁴C - azobisisobutyronitrile). For all mixtures, except dioxane, the experimental data do not support the linear interpolation of the initiation rates, which is usually adopted in literature. In the whole range of monomer feed compositions, any modification of the reaction medium causes a relevant change of the initiation rate, so that the overall pattern is markedly modified. The strongest solvent effect is given by dioxane, which reduces the initiation rates for all monomer mixtures.The radioactive tracer method also enables the determination of the modes of termination, which occur almost exclusively by combination for monomer feed compositions up to about 70 molar % of methyl methacrylate. The $\text{P}\text{?}{}_{\mathrm{w}}\text{P}\text{?}{}_{\mathrm{n}}$ ratios obtained by g.p.c. confirm the general trend of the termination mechanisms as a function of monomer mixture and reaction medium.     

Supported Rh catalysts for methane partial oxidation prepared by OM-CVD of Rh(acac)(CO)2

The organometallics chemical vapour deposition (OM-CVD) technique, using Rh(acac)(CO)₂ as a precursor, was employed for the preparation of heterogeneous Rh catalysts supported on low surface area refractory oxides (α-Al₂O₃, ZrO₂, MgO and La₂O₃). Prepared systems were tested in the methane catalytic partial oxidation (CH₄-CPO) reaction in a fixed bed reactor and compared to a reference catalyst prepared from impregnation of Rh₄(CO)₁₂.Catalysts supported on Al₂O₃, ZrO₂ and MgO show better or comparable performances with respect to the reference system.Complete decomposition of Rh precursor during formation of the metal phase under reductive conditions was investigated by TPRD and confirmed by infrared and mass spectrometry data.Supported Rh phase was characterized by CO and H₂ chemisorption, CO-DRIFT spectroscopy and HRTEM microscopy in fresh and aged selected samples. Rh(I) isolated sites and Rh(0) metal particles were found on fresh catalysts; after ageing an extensive reconstruction occurs mainly consisting in a sintering of Rh isolate sites to metal particles but without large increase in mean particles size.Catalytic performances and Rh species balance were found to be dependent on the support material.     

Experimental Evaluation of Conducted Emissions by Variable-Speed Drives Under Variable Operating Conditions

This paper presents an experimental study about the effects that various operating conditions have on conducted emissions by variable-speed drives. The objective of the research is to determine what quantities most significantly affect emissions so that electromagnetic compatibility test procedures can be carried out under the most appropriate conditions according to the specific destination of the equipment under test. The obtained measurements would so match the standard's requirement that they represent the worst case for the disturbance emission levels. A quantitative analysis has been made possible by introducing two indexes with values determined by emissions over the measurement band. The effects of voltage asymmetry and amplitude, motor operating frequency, and torque applied to it have been investigated. Results show a strong dependence on motor operating frequency and torque and that the fluctuations in the measured emissions largely depend on the measurement configuration adopted.     

The Muon Filter of the L3 detector

In this article we describe the outer part (Muon Filter) of the Hadron Calorimeter of the L3 detector. Construction and performance of the brass chambers, which form the sensitive part of the detector, are reviewed. We also report the results from data taken on two beam tests, at CERN.     

On the solution of a nonlinear matrix equation for MIMO symmetric realizations

A result concerning a particular solution of a nonlinear solution matrix equation reported in a previous paper [2] and interesting for studying SISO systems, is extended to MIMO symmetric realizations. For such a class of systems other important SISO results can be generalized.