Oxidation and diffusion study on AlCrVN hard coatings using oxygen isotopes O and O

The present work aims to investigate the oxidation behaviour of AlCrVN hard coatings of equal composition but of different crystal structure. In order to gain more information about the mechanisms that are active during oxidation, a two-stage oxidation procedure has been applied where different isotopes, ¹⁶O and ¹⁸O, were introduced in each step. The analysis by means of secondary ion mass spectrometry depth profiling with its inherent isotope selectivity provided information on the general oxidation behaviour as well as the oxygen diffusion during the oxidation process. The single-phase coating with its face-centred cubic (fcc) structure presents a higher oxidation resistance as compared to the dual-phase coating containing a wurtzite and an fcc phase. After the annealing treatment the surface of the latter is entirely covered by VO₂ and V₂O₅ as evidenced by Raman spectroscopy. The single-phase coating, on the other hand, reveals unoxidised coating material and AlVO₄ crystals. However, even though exhibiting a significantly different oxidation resistance, the oxygen diffusion is similar. In both cases the peak values of ¹⁸O, which was introduced in the second stage, were found near the oxide-nitride interface indicating that O atoms diffused through the already formed oxides. Additional experiments using a gas mixture comprising natural water vapour H₂¹⁶O and ¹⁸O₂ revealed that mainly the presence of molecular oxygen causes oxidation as with increasing water vapour partial pressure the oxide layer thickness was significantly reduced.     

X-ray photoelectron spectroscopy and thermal desorption spectroscopy comparative studies of L-CVD SnO2 ultra thin films

In this paper we present the results of comparative studies of the chemical stability of L-CVD SnO₂ ultra thin films (20 nm) deposited on the atomically clean Si(100) substrate after their subsequent in situ hydrogenation and oxidation, and then after air exposure. For the control of surface chemistry of these films we used in a comparative way the X-ray Photoemission Spectroscopy (XPS) combined with ion depth profiling (DP XPS) and Thermal Desorption Spectroscopy (TDS). Our XPS experiments showed that the L-CVD SnO₂ ultrathin films after subsequent in situ hydrogenation and oxidation consist of strongly nonstoichiometric layer at the top of Si dioxide substrate. After subsequent air exposure they were covered with undesired 3 monolayers of C contamination and various forms of oxygen. During the TDS procedure a two-step desorption of molecular hydrogen (H₂), water vapor (H₂O), carbon dioxide (CO₂) and atomic oxygen (O) at the temperatures of ~ 530 K and 600 K was observed, respectively. The TDS results were in a good correlation with evident decreasing of the relative concentration of C contaminations, as well as variation of nonstoichiometry of the L-CVD SnO₂ ultra thin films as determined by XPS combined with ion depth profiling.     

A flexible architecture for multi-view 3DTV based on uncalibrated cameras

This paper presents a novel flexible architecture for 3DTV based on multiple uncalibrated cameras. The proposed signal representation improves the interactivity of dense point-based methods, making them appropriate for modeling the scene semantics and free-viewpoint 3DTV applications. The main concern is to address the shortcomings of depth image-based 3D video systems for free-viewpoint visualization, and to provide an efficient implementation of the rendering part which is computationally intensive as well potentially determine the view quality. Novel rendering algorithms are added that specifically aim at solving the rendering artifacts, and sampling issues encountered in wide baseline extensions and arbitrary camera movements. To optimize the process, a “selective” warping technique is proposed that takes the advantage of temporal coherence to reduce the computational overhead. Performance is illustrated on challenging videos to prove the suitability and flexibility of the architecture for advanced 3DTV systems.     

Automatic,fast, online calibration between depth and color cameras

Automatic camera calibration has remained a hard topic in computer vision since its inception due to its reliance on the image correspondence problem. This problem becomes even more pronounced when calibrating a depth image with a color image due to a lack of simple correspondences between the two modalities. In this work, we develop a completely automatic, very fast, online algorithm that demonstrates how a consumer-grade depth camera can be calibrated with a color camera with minimal user interaction.     

沧州地裂缝分布特征及影响因素分析

近年来,沧州地裂缝呈快速发展趋势,给人民的生产和生活造成很大的威胁。在分析了本地区地裂缝的分布规律及发育特征后,从应力来源、基础条件和诱发因素3个方面,对地裂缝的影响因素进行了分析,认为本地区地裂缝的产生多为复合成因,在致裂应力的作用下,浅层水位埋深大、古河道带发育的地区、地层结构条件差异较大的部位最易形成裂缝。     

A simplified correctness proof for a well-known algorithm computing strongly connected components

The computation of the strongly connected components of a directed graph is one of the fundamental algorithmic graph problems. Linear-time algorithms with simple implementations are known. Here a simplified correctness proof for one of these algorithms is presented.     

The development of a time of flight spectrometer for LARN

An elastic recoil detection time of flight system to depth profile light elements has been developed on ALTAÏS, the new Tandetron accelerator at LARN. The detector mounted at 45° from the beam axis consists of two isochronous electron detectors for the timing signal (START and STOP) and a 450 mm² heavy ion PIPS detector that detects the energy of the recoil atoms. The 2MV Tandem accelerator provides heavy ion beams with a maximum energy of 16 MeV depending on the charge transfer efficiency of the gas exchange canal located in the middle of the machine. A large variety of primary ion beams like ²⁸Si, ³⁵Cl, ⁶³Cu, ¹²⁷I or ¹⁹⁷Au can be produced with the SINIX heavy ion source and accelerated on the target. Typical current around 1 nA can be obtained. The energy transfer to the recoil atoms is typically in the MeV range and depends on the mass and the energy of the projectile. Some secondary effects like the energy loss in the carbon foils of the timing detector but also in the entrance window of the energy detector should not be neglected if we try to depth profile light elements with this technique. Time resolution of about 1 ns for the electrons detectors is suitable to obtain 1 amu mass resolution. Some examples of applications will be developed in this paper.     

Detection system for depth profiling of radiotracers

A reliable and efficient detection system essentially needed in the depth profiling of radiotracers consisting of two large PIN-diode arrays has been constructed. The requirements put forward to the detector system and the ability of the PIN-diode array to meet these demands are discussed. A comparison to a conventionally used liquid scintillation detector is presented by measuring an as-implanted ³¹Si profile in amorphous T21 ceramic by both apparatuses.     

Depth extraction using a single moving camera: an integration of depth from motion and depth from stereo

An integrated approach to extract depth, efficiently and accurately, from a sequence of images is presented in this paper. The method combines the ability of the stereo processing to acquire highly accurate depth measurements and the efficiency of spatial and temporal gradient analysis. As a result of this integration, depth measurements of high quality are obtained at a speed approximately ten times greater than that of stereo processing. Without any a priori information of the locations of the points in the scene, the correspondence problem in stereo processing is computationally expensive. In our approach, we use spatial and temporal gradient (STG) analysis, which has been shown to provide depth with great efficiency, but limited accuracy, to guide the matching process of stereo. The camera motion used in the approach can be either lateral or axial. Extensive experiments on real scenes have shown the ability of the integrated approach to acquire depth with a mean error of less than 3%.