12 research outputs found
Modeling the effect of 1 MeV electron irradiation on the performance of n(+)-p-p(+) silicon space solar cells
Get PDFEnergetic particles such as electrons and protons induce severe degradation on the performance of solar cells used to power satellites and space vehicles. This degradation is usually attributed to lattice damage in the active region of the solar cell. One of the phenomena observed in silicon solar cells exposed to 1 MeV electron irradiation is the anomalous degradation of the short circuit current. It initially decreases followed by a recovery before falling again with increasing electron fluence. This behavior is usually attributed to type conversion of the solar cell active region. The other figures of merit, on the other hand, decrease monotonically. In this work numerical simulator SCAPS (Solar Cell Capacitance Simulator) is used to elucidate this phenomenon. The current-voltage characteristics of a Si n+–p–p+ structure are calculated under air mass zero spectrum with the fluence of 1 MeV electrons as a variable parameter. The effect of irradiation on the solar cell is simulated by a set of defects of which the energy levels lie deep in energy gap of silicon (much larger than the characteristic thermal energy kT far from either the conduction or valence band). Although several types of deep levels are induced by irradiation including deep donors (exchange electrons mainly with the conduction band), deep acceptors (exchange electrons mainly with the valence band) and/or generation recombination centers (exchange electrons with both the conduction and valence bands), it was found that, only one of them (the shallowest donor) is responsible for the anomalous degradation of the short circuit current. It will be also shown, by calculating the free charge carrier profile in the active region, that this behavior is not related to type conversion but to a lateral widening of the space charge region
Physical Operations of a Self-Powered IZTO/β-Ga2O3 Schottky Barrier Diode Photodetector
No full textIn this work, a self-powered, solar-blind photodetector, based on InZnSnO (IZTO) as a Schottky contact, was deposited on the top of Si-doped β-Ga2O3 by the sputtering of two-faced targets with InSnO (ITO) as an ohmic contact. A detailed numerical simulation was performed by using the measured J–V characteristics of IZTO/β-Ga2O3 Schottky barrier diodes (SBDs) in the dark. Good agreement between the simulation and the measurement was achieved by studying the effect of the IZTO workfunction, β-Ga2O3 interfacial layer (IL) electron affinity, and the concentrations of interfacial traps. The IZTO/β-Ga2O3 (SBDs) was tested at a wavelength of 255 nm with the photo power density of 1 mW/cm2. A high photo-to-dark current ratio of 3.70×105 and a photoresponsivity of 0.64 mA/W were obtained at 0 V as self-powered operation. Finally, with increasing power density the photocurrent increased, and a 17.80 mA/W responsivity under 10 mW/cm2 was obtained
The Tuareg mythical universe in the work of Ibrahim Al Koni
No full textCe travail tente de répondre à la problématique suivante : de quelle façon un écrivain, en l’occurrence Ibrahim Al Koni, peut-il témoigner de l’histoire et de la culture de son peuple, les Touaregs (en danger d’extinction), sans verser dans le discours ethnographique ou le manifeste politique ? La réponse qui vient immédiatement à l’esprit c’est : par l’écriture.Or l’oralité étant le mode d’expression et de transmission principal de la société touarègue, l’auteur va se trouver dans la nécessité d’user d’une langue « étrangère » (l’arabe), et d’une forme exogène (le roman) pour accomplir cette œuvre. Mais la gageure ne s’arrête pas là : Al Koni se propose de restituer à son peuple des valeurs et un mode de vie menacés par l’oubli et la dislocation de l’espace traditionnel nomade. Il lui faut alors inventer une matrice originale capable de véhiculer ces valeurs et de retrouver l’oasis perdue « Waw » baignant dans la parole première du livre des Ancêtres « Anhi ». C’est par l’investissement des mythes fondateurs touaregs dans la trame des intrigues romanesques qu’il réussira cette alchimie et parviendra à fonder un genre nouveau dans la littérature arabe et mondiale contemporaines : Le Roman du désert.This work aims at answering the following question : how can a writer, in this case Ibrahim Al Koni, testify to the history and culture of his people, the Touaregs (endangered), without producing neither an ethnographic speech nor a political manifest ? The answer just immediately to mind is : by writing. However, the main mode of expression and transmission in the touareg society is orality. That is why the author will need to use a “foreign” language (arabic) and an exogenous form (the novel) to accomplish this mission. But the challenge does not stop here : Al Koni intends to give back to his people many values and a way of life threatened by oblivion and by the collapse of the traditional nomadic space. He than needs to invent an original matrix able to convey these values and find “Waw”, the lost oasis, bathing in the prime speech of the ancestors book, “Anhi”. By investing touaregs founding myths in the frame of romanesques intrigues, Al Koni manages to succeed this alchemy and builds a new genre in the arab and contemporary world literature : The Novel of the desert
Crack growth optimization using eddy current testing and genetic algorithm for estimating the stress intensity factors
No full textThis study developed a procedure for rapidly reconstructing a crack profile for calculating the parameters of fracture mechanics such as stress intensity factor with energy release rate (J) and displacement opening crack tip using data from the eddy current sensor. The inverse problem focused on adopting genetic algorithms to solve the direct problem iteratively. The use of the differential probe allows a rapid and precise resolution of the direct problem. The incident field produced by the two coils is determined using the 3D finite element results and the variation of impedance in each coil due to the crack. For the inverse problem, the crack’s surface is considered regular shape in terms of dimensions, and the sensor’s impedance expresses the objective function in terms of the width and length of the crack. The evaluation of the shape function and mesh matrix is made dependent on the iterative process, which makes the reversal procedure computationally lightweight when using genetic algorithms. © The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2024.</p
Analysis of the VUV emission spectrum of the Er3+ ion (Er IV)
No full textInternational audienceThis paper reports a summary of results obtained on the spectrum of the Er3+ ion (Er IV). The analysis of high resolution VUV emission spectrum led to the identification of about 590 spectral lines in the wavelength region of (851Å- 2277Å) and the determination of 120 energy levels belonging to the 4f11, 4f105d, 4f106s and 4f106p configurations, above the ground level 4f11 4I15/2. Parametric studies of the configurations including configuration interactions provided level compositions in intermediate coupling scheme
Tryptophan and serotonin levels as potent biomarkers in diabetes mellitus complications: a new approach of diagnostic role
No full textObjective: Alterations in the serotonergic system were verified to act a role in the pathogenesis of altered neurological and psychiatric diseases. In recent years, Tryptophan (Trp) and serotonin (5-HT) levels have been considered potent biomarkers of diabetes mellitus (DM). Method: The different Trp metabolism may also play roles in the pathogenesis of DM and mounting risk of complications. The whole blood (WB) 5-HT level was mainly lower among diabetic patients compared to others. That is mostly derived from a lower platelet concentration of 5-HT in these patients. Results: Indeed, 5-HT level can be considered a potent biomarker for early detection of DM complications. Besides, it was proved that outside the digestive and central nervous systems, 5-HT was discovered in beta cells, and scientists have been attempting to realize its mechanism of action ever since. Towards to end, the determination methods, biomarker�s role, and approaches of 5-HT and Trp levels were thoroughly investigated in both healthy and diabetic patients with or without complications. Moreover, the association between insulin and 5-HT has been specifically discussed. Conclusions: Our study concluded that Trp and 5-HT levels could be exclusively applied for early diagnosis of DM complications as well as many other complications. Graphical abstract: Figure not available: see fulltext. © 2022, The Author(s), under exclusive licence to Tehran University of Medical Sciences
Civil society and political change in Morocco
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Privacy preserving linkage and sharing of sensitive data
Get PDF2018 Summer.Includes bibliographical references.Sensitive data, such as personal and business information, is collected by many service providers nowadays. This data is considered as a rich source of information for research purposes that could benet individuals, researchers and service providers. However, because of the sensitivity of such data, privacy concerns, legislations, and con ict of interests, data holders are reluctant to share their data with others. Data holders typically lter out or obliterate privacy related sensitive information from their data before sharing it, which limits the utility of this data and aects the accuracy of research. Such practice will protect individuals' privacy; however it prevents researchers from linking records belonging to the same individual across dierent sources. This is commonly referred to as record linkage problem by the healthcare industry. In this dissertation, our main focus is on designing and implementing ecient privacy preserving methods that will encourage sensitive information sources to share their data with researchers without compromising the privacy of the clients or aecting the quality of the research data. The proposed solution should be scalable and ecient for real-world deploy- ments and provide good privacy assurance. While this problem has been investigated before, most of the proposed solutions were either considered as partial solutions, not accurate, or impractical, and therefore subject to further improvements. We have identied several issues and limitations in the state of the art solutions and provided a number of contributions that improve upon existing solutions. Our rst contribution is the design of privacy preserving record linkage protocol using semi-trusted third party. The protocol allows a set of data publishers (data holders) who compete with each other, to share sensitive information with subscribers (researchers) while preserving the privacy of their clients and without sharing encryption keys. Our second contribution is the design and implementation of a probabilistic privacy preserving record linkage protocol, that accommodates discrepancies and errors in the data such as typos. This work builds upon the previous work by linking the records that are similar, where the similarity range is formally dened. Our third contribution is a protocol that performs information integration and sharing without third party services. We use garbled circuits secure computation to design and build a system to perform the record linkages between two parties without sharing their data. Our design uses Bloom lters as inputs to the garbled circuits and performs a probabilistic record linkage using the Dice coecient similarity measure. As garbled circuits are known for their expensive computations, we propose new approaches that reduce the computation overhead needed, to achieve a given level of privacy. We built a scalable record linkage system using garbled circuits, that could be deployed in a distributed computation environment like the cloud, and evaluated its security and performance. One of the performance issues for linking large datasets is the amount of secure computation to compare every pair of records across the linked datasets to nd all possible record matches. To reduce the amount of computations a method, known as blocking, is used to lter out as much as possible of the record pairs that will not match, and limit the comparison to a subset of the record pairs (called can- didate pairs) that possibly match. Most of the current blocking methods either require the parties to share blocking keys (called blocks identiers), extracted from the domain of some record attributes (termed blocking variables), or share reference data points to group their records around these points using some similarity measures. Though these methods reduce the computation substantially, they leak too much information about the records within each block. Toward this end, we proposed a novel privacy preserving approximate blocking scheme that allows parties to generate the list of candidate pairs with high accuracy, while protecting the privacy of the records in each block. Our scheme is congurable such that the level of performance and accuracy could be achieved according to the required level of privacy. We analyzed the accuracy and privacy of our scheme, implemented a prototype of the scheme, and experimentally evaluated its accuracy and performance against dierent levels of privacy
Non-destructive inspection in industrial equipment using robotic mobile manipulation
No full textPublisher Copyright: © 2016 Author(s).MAINBOT project has developed service robots based applications to autonomously execute inspection tasks in extensive industrial plants in equipment that is arranged horizontally (using ground robots) or vertically (climbing robots). The industrial objective has been to provide a means to help measuring several physical parameters in multiple points by autonomous robots, able to navigate and climb structures, handling non-destructive testing sensors. MAINBOT has validated the solutions in two solar thermal plants (cylindrical-parabolic collectors and central tower), that are very demanding from mobile manipulation point of view mainly due to the extension (e.g. a thermal solar plant of 50Mw, with 400 hectares, 400.000 mirrors, 180 km of absorber tubes, 140m height tower), the variability of conditions (outdoor, day-night), safety requirements, etc. Once the technology was validated in simulation, the system was deployed in real setups and different validation tests carried out. In this paper two of the achievements related with the ground mobile inspection system are presented: (1) Autonomous navigation localization and planning algorithms to manage navigation in huge extensions and (2) Non-Destructive Inspection operations: thermography based detection algorithms to provide automatic inspection abilities to the robots.Peer reviewe
HiRISE - High-Resolution Imaging and Spectroscopy Explorer - Ultrahigh resolution, interferometric and external occulting coronagraphic science
No full textRecent solar physics missions have shown the definite role of waves and magnetic fields deep in the inner corona, at the chromosphere-corona interface, where dramatic and physically dominant changes occur. HiRISE (High Resolution Imaging and Spectroscopy Explorer), the ambitious new generation ultra-high resolution, interferometric, and coronagraphic, solar physics mission, proposed in response to the ESA Voyage 2050 Call, would address these issues and provide the best-ever and most complete solar observatory, capable of ultra-high spatial, spectral, and temporal resolution observations of the solar atmosphere, from the photosphere to the corona, and of new insights of the solar interior from the core to the photosphere. HiRISE, at the L1 Lagrangian point, would provide meter class FUV imaging and spectro-imaging, EUV and XUV imaging and spectroscopy, magnetic fields measurements, and ambitious and comprehensive coronagraphy by a remote external occulter (two satellites formation flying 375 m apart, with a coronagraph on a chaser satellite). This major and state-of-the-art payload would allow us to characterize temperatures, densities, and velocities in the solar upper chromosphere, transition zone, and inner corona with, in particular, 2D very high resolution multi-spectral imaging-spectroscopy, and, direct coronal magnetic field measurement, thus providing a unique set of tools to understand the structure and onset of coronal heating. HiRISE’s objectives are natural complements to the Parker Solar Probe and Solar Orbiter-type missions. We present the science case for HiRISE which will address: i) the fine structure of the chromosphere-corona interface by 2D spectroscopy in FUV at very high resolution; ii) coronal heating roots in the inner corona by ambitious externally-occulted coronagraphy; iii) resolved and global helioseismology thanks to continuity and stability of observing at the L1 Lagrange point; and iv) solar variability and space climate with, in addition, a global comprehensive view of UV variability. © 2022, The Author(s)
