Transnational Corporations - Key Enablers Globalization

Romania, Romanian economic agents have become in recent years present ever more active in world trade. Association agreements agreed with the European Union and beyond, opening Romania and Romanian participants in international trade relations, prospects of major deep involvement in the world flow of values and knowledge. But it also means aligning our trade laws to European legislation profile, with priority to Community law and assimilation regulatory provisions of international conventions ratified across Romania as part of national law rules. Transnational corporations, which operate in more than one country or nation at a time, have become some of the most powerful economic and political entities in the world today. The United Nations has justly described these corporations as “the productive core of the globalizing world economy.globalization, transnational corporations, global village, ecommerce

Blind Source Separation in Polarimetric SAR Interferometry

International audiencePolarimetric incoherent target decomposition aims in access-ing physical parameters of illuminated scatters through the analysis of target coherence or covariance matrix. In this framework, Independent Component Analysis (ICA) was recently proposed as an alternative method to Eigenvector decomposition to better interpret non-Gaussian heterogeneous clutter (inherent to high resolution SAR systems). Until now, the two main drawbacks reported of the aforementioned method are the greater number of samples required for an unbiased estimation, when compared to classical Eigenvector decomposition and the inability to be employed in scenarios under Gaussian clutter assumption. First, a Monte Carlo approach is performed in order to investigate the bias in estimating the Touzi Target Scattering Vector Model (TSVM) parameters when ICA is employed. A RAMSES X-band image acquired over Brétigny, France is taken into consideration to investigate the bias estimation under different scenarios. Finally, some results in terms of POLinSAR coherence optimization [1] in the context of ICA are proposed

Messung und Modellierung der Dynamik der optisch und elektrisch induzierten Dissipation in Quanten-Hall-Systemen

The subjects of this work are the experimental investigations of optically and electrically induced dissipation in two-dimensional electron systems under Quantum Hall (QH) conditions and the numerical investigations of the dynamic conductivity and the equilibrium properties of the electron system subjected to a terahertz (THz) radiation. The experiments are interesting due to the possibility to investigate the single pulse shape of the electron system response in the real-time domain. The numerical investigations could give a picture of the physics behind the THz interaction with the electron system. The electrically induced dissipation is realized by applying supercritical electrical rectangular pulses to the QH systems with Corbino geometry. The optically induced dissipation is realized by applying subcritical electrical rectangular pulses to the QH systems and at the same time subjecting the sample to a THz radiation. The sample response is measured by a serial resistor and displayed on an digital oscilloscope. As a THz source, a p-Ge laser system was used. It emits radiation of frequency of 2THz corresponding to photon energies of 10meV. The measurements were performed on GaAs/AlGaAs heterostructures at low temperatures T<4K and high magnetic fields B<6T. We investigated the excitation and relaxation times as functions of the source-drain voltage, electron mobility, magnetic field and temperature. These dependences were explained on the basis of quasi-classical drift, quasi-elastic-inter-Landau-level-scattering and quasi-local transport models. The photoresponse is given by the cyclotron resonance (CR) and the bolometric (BO) contributions. Especially, the BO contribution shows an interesting double-peak structure. By the numerical investigations we have found that the elevated electron temperature by THz radiation shows a double-peak structure at even filling factors at certain lattice temperatures and photon energies as observed in the experiments.Diese Arbeit untersucht sowohl experimentell die optisch und elektrisch induzierte Dissipation in zweidimensionalen Elektronensystemen unter Quanten-Hall- (QH-) Bedingungen als auch numerisch die dynamische Leitfähigkeit und die Gleichgewichtseigenschaften von Elektronensystemen, wenn diese einer Terahertz- (THz-) Strahlung ausgesetzt werden. Die Experimente sind interessant wegen der Möglichkeit, den Zeitverlauf von einzelnen Impulsen zu messen. Die numerischen Untersuchungen konnten ein Bild der physikalischen Prozesse, die der Wechselwirkung der Elektronensysteme mit der THz-Strahlung zugrunde liegen, liefern. Die elektrisch induzierte Dissipation wurde ausgelöst durch die Anwendung überkritischer Rechteckimpulse auf QH-Systeme mit Corbino-Geometrie. Die optisch induzierte Dissipation dagegen wurde ausgelöst durch die gleichzeitige Anwendung unterkritischer elektrischer Rechteckimpulse und einer THz-Strahlung auf die QH-Systeme. Das Antwortsignal der Probe wird über einen seriellen Widerstand gemessen und auf einem Digital-Oszilloskop dargestellt. Als THz-Quelle wurde ein p-Ge-Laser verwendet. Dieser Laser emittiert eine Strahlung mit Frequenzen um 2 THz (entsprechend einer Photonenenergie von etwa 10meV). Die Messungen wurden an GaAs/GaAlAs-Heterostrukturen bei tiefen Temperaturen von T<4K und bei hohen Magnetfeldern von B<6T durchgeführt. Wir untersuchten die Anregungs- und Abklingzeiten als Funktion der Source-Drain-Spannung, der Elektronenbeweglichkeit, des magnetischen Feldes und der Temperatur. Diese Abhängigkeiten wurden erklärt auf der Basis verschiedener Modelle: des quasi-klassischen Driftmodells, des Modells der quasi-elastischen Inter-Landau-Niveau-Streuung und des quasi-lokalen Transportmodells. Die Photoresponse setzt sich aus zyklotronresonanten (ZR) und bolometrischen (BO) Anteilen zusammen. Der BO-Anteil zeigt eine interessante Doppel-Maximum-Struktur. Durch die numerischen Untersuchungen fanden wir eine Doppel-Maximum-Struktur für die Elektronentemperatur bei bestimmten Gittertemperaturen und Photonenenergien, die infolge der THz-Strahlung erhöht ist. Dieses Ergebnis steht in Übereinstimmung mit unseren experimentellen Befunden

Hierarchical Segmentation of Polarimetric SAR Images Using Heterogeneous Clutter Models

International audienceIn this paper, heterogeneous clutter models are used to describe polarimetric synthetic aperture radar (PolSAR) data. The KummerU distribution is introduced to model the PolSAR clutter. Then, a detailed analysis is carried out to evaluate the potential of this new multivariate distribution. It is implemented in a hierarchical maximum likelihood segmentation algorithm. The segmentation results are shown on both synthetic and high-resolution PolSAR data at the X- and L-bands. Finally, some methods are examined to determine automatically the "optimal" number of segments in the final partition

Enhancing Hyperspectral Image Quality using Nonlinear PCA

International audienceIn this paper, we propose a new method aiming at reducing the noise in hyperspectral images. It is based on the nonlinear generalization of Principal Component Analysis (NLPCA). The NLPCA is performed by an auto associative neural network that have the hyperspectral image as input and is trained to reconstruct the same image at the output. Thanks to its bottleneck structure, the AANN forces the hyper spectral image to be projected in a lower dimensionality feature space where noise as well as both linear and nonlinear correlations between spectral bands are removed. This process permits to obtain enhancements in terms of hyperspectral image quality. Experiments are conducted on different real hyper spectral images, with different contexts and resolutions. The results are qualitatively and quantitatively discussed and demonstrate the interest of the proposed method as compared to traditional approaches

Multi-Lag Phase Space Representations for Transient Signals Characterization

International audienceTransient signals are very difficult to characterize due to their short duration and their wide frequency content. Various methods such as spectrogram and wavelet decomposition have already been extensively used in the literature to detect them, but show limits when it comes to near similar transients discrimination. In this paper, we propose the multi-lag phase space analysis as a way to characterize them. This data-driven method enables the comparison between features extracted from two different signals. In an example, we compare the multi-lag phase space representations of three similar transients and show that common features can be found to discriminate them. Finally the results are compared with a wavelet decomposition

Adaptive Waveforms for Flow Velocity Estimation Using Acoustic Signals

International audienceIn this paper, we introduce a general framework for waveform design and signal processing, dedicated to the study of turbulent flow phenomena. In a bi-static configuration, by transmitting a specific waveform with a predefined instantaneous frequency law (IFL), within the bounds of the Kolmogorov spectrum, the turbulent media will modify the IFL at the receiving side. We propose a new methodology to estimate this change and to exploit it for velocity estimation using acoustic signals. In this way, the amplitude based velocity estimation techniques can be substituted by non stationary time - frequency signal processing. This technique proves to be more robust in terms of interferences and can provide a more detailed representation of any turbulent environment

Polarimetric Incoherent Target Decomposition by Means of Independent Component Analysis

International audienceThis paper presents an alternative approach for polarimetric incoherent target decomposition dedicated to the analysis of very-high resolution POLSAR images. Given the non-Gaussian nature of the heterogeneous POLSAR clutter due to the increase of spatial resolution, the conventional methods based on the eigenvector target decomposition can ensure uncorrelation of the derived backscattering components at most. By introducing the Independent Component Analysis (ICA) in lieu of the eigenvector decomposition, our method is rather deriving statistically independent components. The adopted algorithm - FastICA, uses the non-Gaussianity of the components as the criterion for their independence. Considering the eigenvector decomposition as being analogues to the Principal Component Analysis (PCA), we propose the generalization of the ICTD methods to the level of the Blind Source Separation (BSS) techniques (comprising both PCA and ICA). The proposed method preserves the invariance properties of the conventional ones, appearing to be robust both with respect to the rotation around the line of sight and to the change of the polarization basis. The efficiency of the method is demonstrated comparatively, using POLSAR Ramses X-band and ALOS L-band data sets. The main differences with respect to the conventional methods are mostly found in the behaviour of the second most dominant component, which is not necessarily orthogonal to the first one. The potential of retrieving non-orthogonal mechanisms is moreover demonstrated using synthetic data. On expense of a negligible entropy increase, the proposed method is capable of retrieving the edge diffraction of an elementary trihedral by recognizing dipole as the second component