Embedded Vision Systems: A Review of the Literature

Over the past two decades, the use of low power Field Programmable Gate Arrays (FPGA) for the acceleration of various vision systems mainly on embedded devices have become widespread. The reconfigurable and parallel nature of the FPGA opens up new opportunities to speed-up computationally intensive vision and neural algorithms on embedded and portable devices. This paper presents a comprehensive review of embedded vision algorithms and applications over the past decade. The review will discuss vision based systems and approaches, and how they have been implemented on embedded devices. Topics covered include image acquisition, preprocessing, object detection and tracking, recognition as well as high-level classification. This is followed by an outline of the advantages and disadvantages of the various embedded implementations. Finally, an overview of the challenges in the field and future research trends are presented. This review is expected to serve as a tutorial and reference source for embedded computer vision systems

GROWTH OF IV-VI, II-VI AND III-V SEMICONDUCTOR COMPOUNDS BY HOT WALL EPITAXY

Dans cet article sont présentés les derniers résultats obtenus sur des couches minces épitaxiées de CdS, CdTe, de sels de plomb, de matériau semimagnétique Pb1-xMnx Te et de GaAs. Ces couches minces sont préparées en utilisant la nouvelle technique nommée "Hot Wall Epitaxy" (HWE). Les principales caractéristiques de cette technique sont sa simplicité d'emploi et la possibilité de réaliser les couches minces pour des conditions plus proches de l'équilibre thermodynamique que celles des autres méthodes d'évaporation. Les couches minces épitaxiées ont été caractérisées par SEM, effet-Hall et diffraction des rayons X. Il a été ainsi prouvé que les couches minces obtenues par HWE ont des caractéristiques aussi bonnes que les cristaux massifs. Par exemple, les mobilités des couches monocristallines de PbTe préparées sur BaF2 étaient 3xl04cm2/Vs (77K ) pour les échantillons de type n et 104cm2/ Vs pour les échantillons de type p. Il a été possible d'obtenir des couches épitaxiées de Pb1-xMnxTe (x=1-2%) ayant une grande mobilité et une faible concentration de porteurs. Les couches minces de CdS et CdTe déposées sur BaF2, SrF2 et CdTe massif ont une croissance épitaxiale et une structure granulaire. Des couches type n ont été obtenues en prenant l'Indium comme dopant. La concentration typique en porteurs était 2x1017cm-3 pour les couches de CdTe et 5x1017cm-3 pour CdS, les valeurs maximales de mobilité (300K) 230 cm2 /Vs pour CdS et 600cm2/Vs pour CdTe.In this work we present a summary of the latest results obtained in our labs on epitaxial layers of CdS, CdTe, Pb-salts, the semimagnetic compound Pbl-xMnxTe and GaAs. These layers have been prepared using a relatively new evaporation method called Hot wall Epitaxy (HWE). The main characteristic of this technic is its simplicity and the possibility to grow epitaxial layers under conditions closer to thermodynamic equilibrium than most other evaporation methods. The layers have been characterized using procedures like SEM. Hall-Effect and X-ray diffraction. The results prove that the properties of the layers obtained by HWE are nearly as good as those of bulk-material. Monocrystalline PbTe samples were grown on BaF2 with mpbilities at 3x104cm2/Vs at 77K for n-type and 1x104cm2/Vs for p-type samples. We were able to grow Pb1-xMnxTe (x=1-2%) samples with high mobility and low carrier concentration. Thin films of CdS and CdTe deposited on BaF2, SrF2 and bulk CdTe grew epitaxial on these substrates and had a grained structure. We obtained n-type films using Indium as a dopant. Electron concentration was typically 2x1017cm-3 in CdTe and 5x1017cm-3 in CdS. Room temperature values of electron mobility of up to 230cm2/Vs for CdS and 600cm2/Vs for CdTe were obtained

Electron tunneling in heavily In-doped polycrystalline CdS films

The electrical properties of heavily In‐doped polycrystalline CdS films have been studied as a function of the doping level. The films were prepared by vacuum coevaporation of CdS and In. Conductivity and Hall measurements were performed over the temperature range 77-400 K. The conductivity decreases weakly with the temperature and shows a tendency towards saturation at low temperatures. A simple relationship σ=σ0(1+βT2) is found in the low‐temperature range. The temperature dependence of the mobility is similar to that of the conductivity since the Hall coefficient is found to be a constant in the whole temperature range. We interpret the experimental results in terms of a modified version of grain‐boundary trapping Seto"s model, taking into account thermionic emission and tunneling of carriers through the potential barriers. The barriers are found to be high and narrow, and tunneling becomes the predominating transport mechanism

Internationalizing sales research : current status, opportunities, and challenges

With economic activity in emerging markets growing at 40 percent, and with 10 percent and more of the firms in the Global Fortune 500 now headquartered in emerging economies, intense interest lies in the globalization of business activities, including the sales function. This systematic review of the international sales literature in a selection of the most influential journals explains, consolidates, and analyzes current knowledge. This paper also explores the challenges inherent in conducting international sales research, including conceptualization, research management, and data collection issues. Finally, we suggest ways to move forward for researchers in this field, including pertinent topics and how methodological and practical constraints might be addressed