ÐDetecting faces in images with complex backgrounds is a difficult task. Our approach, which obtains state of the art results, is based on a new neural network model: the Constrained Generative Model (CGM). Generative, since the goal of the learning process is to evaluate the probability that the model has generated the input data, and constrained since some counterexamples are used to increase the quality of the estimation performed by the model. To detect side view faces and to decrease the number of false alarms, a conditional mixture of networks is used. To decrease the computational time cost, a fast search algorithm is proposed. The level of performance reached, in terms of detection accuracy and processing time, allows to apply this detector to a real world application: the indexation of images and videos.
Electrical and optical nonuniformity of Siimplanted and rapid thermal annealed InP:FeThe behavior of semi-insulating InP:Fe under high electric field is investigated. The current-voltage (1-V) characteristics are studied on both long liquid-encapsulated Czochralski-grown samples and short epitaxial-grown layers. These characteristics show a linear regime at low voltages followed, for higher voltages, by a nonlinear behavior and a current breakdown. The critical electric field at which the nonlinearity begins is found to be independent of the sample thickness, the material compensation, and the nature of the contacts, and is equal to 10 kV/cm. This fact rules out the usual explanation in terms of Lampert's injection theory. In the nonlinear regime, a slow transient response ( =: 1 s at room temperature) is observed only for long samples. The time constant of this effect exhibits a thermal activation energy ( ~0.64 eV) close to that of the iron-related deep level. Field-dependent effects on the thermal emission rate and the capture cross section are discussed. Considering a field enhancement of the capture cross section, we propose a model to explain both the nonlinear characteristics and the slow dynamic behavior of long samples. The current breakdown observed at higher fields is attributed to an impact ionization of the deep levels and not to a trap-filled-limit voltage as previously reported.8340
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