Panoramic Depth Imaging: Single Standard Camera Approach

In this paper we present a panoramic depth imaging system. The system is mosaic-based which means that we use a single rotating camera and assemble the captured images in a mosaic. Due to a setoff of the camera's optical center from the rotational center of the system we are able to capture the motion parallax effect which enables stereo reconstruction. The camera is rotating on a circular path with a step defined by the angle, equivalent to one pixel column of the captured image. The equation for depth estimation can be easily extracted from the system geometry. To find the corresponding points on a stereo pair of panoramic images the epipolar geometry needs to be determined. It can be shown that the epipolar geometry is very simple if we are doing the reconstruction based on a symmetric pair of stereo panoramic images. We get a symmetric pair of stereo panoramic images when we take symmetric pixel columns on the left and on the right side from the captured image center column. Epipolar lines of the symmetrical pair of panoramic images are image rows. The search space on the epipolar line can be additionaly constrained. The focus of the paper is mainly on the system analysis. Results of the stereo reconstruction procedure and quality evaluation of generated depth images are quite promissing. The system performs well for reconstruction of small indoor spaces. Our finall goal is to develop a system for automatic navigation of a mobile robot in a room.     

Automatic reconstruction of 3D human arm motion from a monocular image sequence

A model-based approach to reconstruction of 3D human arm motion from a monocular image sequence taken under orthographic projection is presented. The reconstruction is divided into two stages. First, a 2D shape model is used to track the arm silhouettes and second-order curves are used to model the arm based on an iteratively reweighted least square method. As a result, 2D stick figures are extracted. In the second stage, the stick figures are backprojected into the scene. 3D postures are reconstructed using the constraints of a 3D kinematic model of the human arm. The motion of the arm is then derived as a transition between the arm postures. Applications of these results are foreseen in the analysis of human motion patterns. Received: 26 January 1996 / Accepted: 17 July 1997     

Development of GPON upstream physical-media-dependent prototypes

This paper presents three new gigabit-capable passive optical network (GPON) physical-media-dependent (PMD) prototypes: a burst-mode optical transmitter, an avalanche photodiode/transimpedance amplifier (APD-TIA), and a burst-mode optical receiver. With these, point-to-multipoint (P2MP) upstream transmission can be realized in a high-performance GPON at 1.25 Gb/s. Performance measurements on the new burst-mode upstream PMD modules comply with GPON uplink simulations. The laser transmitter can quickly set and stabilize the launched optical power level over a wide temperature range with better than 1-dB accuracy. A burst-mode receiver sensitivity of -32.8 dBm (BER=10/sup -10/) is measured, combined with a dynamic range of 23 dB at a fixed APD avalanche gain of 6. Full compliance is achieved with the recently approved ITU-T Recommendation G.984.2 supporting an innovative overall power-leveling mechanism.     

Effects of glucose and acid-hydrolysed vegetable protein on the volatile components of extruded wheat starch

The volatile components produced in wheat starch, and wheat starch combined with 1% glucose, 1% acid-hydrolysed vegetable protein (aHVP) or 1% glucose and 1% aHVP, extruded under different processing conditions (temperatures of 150 or 180 °C and moisture content of 16% or 20%) were identified by gas chromatography-mass spectrometry (GC-MS). Gas chromatography olfactometry (GCO) was used to assess the odour intensity of volatile components present in the starch and starch/glucose/aHVP extrudates obtained at 180 °C. In total, 70 compounds were identified in the eight extrudates. The smallest number (24) was found in the extrudate of the starch/glucose mixture and the largest number (67) in the extrudate of the starch/glucose/aHVP mixture, both processed at 180 °C. Lipid degradation products, such as alkanals, 2-alkanones, 2-alkenals and 2,4-alkadienals, were present in all extrudates in significant quantities. However, in those extrudates containing aHVP, Strecker aldehydes were quantitatively the dominant components. Maillard reaction products, such as pyrroles and pyrazines, were only found in extrudates containing both glucose and aHVP whereas sulphur-containing aliphatic compounds were found in all extrudates containing aHVP. The production of the Maillard reaction products and sulphur-containing compounds were favoured by extrusion at 180 °C. Sensory analyses showed that each of the eight extrudates had different odours, and that the extrudates containing both glucose and aHVP possessed the highest overall odour intensity.     

Volatile aroma components of soy protein isolate and acid-hydrolysed vegetable protein

The volatile aroma components of soy protein isolate (SPI) and acid-hydrolysed vegetable protein (aHVP) were compared by gas chromatography–mass spectrometry (GC–MS) and gas chromatography olfactometry (GCO). Major differences were found between the two soy-based products. Aliphatic aldehydes and ketones were mainly found in SPI, whereas pyrazines and sulphur-containing compounds were dominant in aHVP. Analyses of the non-volatile components showed that SPI was mainly protein (82.5%) with some lipid (3.5%), whereas aHVP contained no protein, only free amino acids (18.4%) and a trace quantity of lipid (0.4%). Polyunsaturates (47.8%), followed by saturates (24.9%) and monounsaturates (14.8%) dominated the fatty acid profile of the SPI lipid fraction. Both SPI and aHVP had a free fatty acid content <0.1%. Sensory analyses of aqueous suspensions of SPI and aHVP demonstrated significant differences in the odours of the two products. Compounds responsible for some of these differences were identified by GCO and GC–MS analyses of aqueous suspensions. The possible role of SPI and aHVP in the development of aroma in extrudates containing these soy products is discussed.     

Strain Hardening Behavior of Dual-Phase Steels

A detailed qualitative and quantitative examination of the microstructure and mechanical properties of three different classes of DP600 and DP450 dual-phase (DP) steels was carried out. The tested DP steels are characterized by different alloying elements: aluminum, boron, and phosphorus. Among them, aluminum DP steels showed the lowest percentages of hard phases, while phosphorus DP steels exhibited the highest resistance values. The Hollomon, Pickering, Crussard–Jaoul (CJ), and Bergstrom models were used to reproduce the strain hardening behavior of DP steels. Relationships that correlate the fitting parameters with the chemical composition and the thermal cycle parameters were found, and the predictive abilities of different models were evaluated. The Pickering equation, among the tested models, is the best one in the reproduction of the experimental stress-strain data.     

Recovery of parametric models from range images: the case forsuperquadrics with global deformations

A method for recovery of compact volumetric models for shape representation of single-part objects in computer vision is introduced. The models are superquadrics with parametric deformations (bending, tapering, and cavity deformation). The input for the model recovery is three-dimensional range points. Model recovery is formulated as a least-squares minimization of a cost function for all range points belonging to a single part. During an iterative gradient descent minimization process, all model parameters are adjusted simultaneously, recovery position, orientation, size, and shape of the model, such that most of the given range points lie close to the model's surface. A specific solution among several acceptable solutions, where are all minima in the parameter space, can be reached by constraining the search to a part of the parameter space. The many shallow local minima in the parameter space are avoided as a solution by using a stochastic technique during minimization. Results using real range data show that the recovered models are stable and that the recovery procedure is fast     

Model of hydrogen behaviour in enamelling grade steels

A model has been developed of the behaviour of hydrogen in enamelling-grade steels in relation to the delayed defect of blow-off of enamelled surface (fishscaling). The model is based on current theories concerning reversible and irreversible trapping of hydrogen in metallic materials. It leads to the establishment of a free hydrogen parameterC _L which can be used to assess the susceptibility of a steel to fishscaling following the usual enamelling processess. The model can also be used to study the effect of both thermomechanical steelmaking cycles and enamelling processes on resistance to the defect.Nomenclature E _aD Activation energy of hydrogen diffusion through normal lattice - E _s Saddle-point energy - E _B Trap binding energy - E _aT Trap activation energy=E_s+E_B - A Trapping site - B Normal lattice site - v ₀ Vibration frequency of hydrogen at a normal lattice site - v ₁ Vibration frequency of hydrogen at a trapping site - N _L Density of normal lattice sites for hydrogen - N _T Density of trapping sites for hydrogen - C _L Concentration of hydrogen on lattice sites - C _T Concentration of hydrogen captured on traps - k Probability of trapping=v₀ exp(–E _s/R T) - p Probability of detrapping =v ₁ N _L exp (–E _aT/R T) - n Fraction of trapping sites occupied with hydrogen atoms among the total trapping sites=C _T/N _T - t Time - T Temperature - R Gas constant     

Elastic and anelastic properties of Marval 18 steel

Marval 18 is a precipitation hardened steel with particularly high hardness and low creep, presently used for constructing parts of the interferometers for the detection of gravitational waves in the experiments VIRGO and LIGO. The elastic moduli have been measured in samples subjected to the same treatments as the parts of the interferometer VIRGO. In addition, the anelastic spectra of samples subjected to different thermal treatments have been measured between 50 and 350 K. It is found that, in the absence of plastic deformation, the elastic energy loss coefficient under flexural vibrations around 1 kHz can vary by more than one order of magnitude depending on the thermal treatments, and is dominated by the thermoelastic effect. The main reason for such strong variations is supposed to be the dependence of the thermal conductivity on the average sizes and distances between the precipitate particles.