Efecto de la presión de confinamiento y el método de deposición sobre la respuesta de corte no drenada de arena de densidad media

This study examines the effects of the confining pressure and sample preparation method on the shearing behavior shown by sand from the Chlef River (Algeria). Undrained monotonic triaxial compression tests were performed on samples with an initial relative density of 50% at initial confining pressures of 50 to 200 kPa. Samples were prepared using two depositional methods: dry funnel pluviation and wet deposition. Our results reveal marked differences in the undrained shearing responses produced under identical conditions of density and stress and therefore determined by the soil fabric. Thus, at low confining pressures, samples prepared by the wet deposition method showed complete static liquefaction (zero effective confining pressure and zero stress difference). For both sample types, as confining pressures increased, effective stress paths exhibited increasing resistance to liquefaction indicated by increasing dilatant tendencies.En este trabajo se han estudiado los efectos de la presión de confinamiento y los métodos de preparación de muestras sobre el comportamiento de rotura de arena Chlef. Los resultados de las pruebas sin escurrir monótona de compresión triaxial realizadas en muestras con una densidad relativa inicial del 50% y presiones de confinamiento inicial variaron desde 50 hasta 200 kPa. Las muestras fueron preparadas por dos métodos de deposición seca con embudo de pluviacion y deposición húmeda. Se encontró que existía una marcada diferencia en el comportamiento sin escurrir a pesar de que las condiciones de la densidad y el estrés eran idénticas. La conclusión fue que la estructura del suelo fue la responsable de este resultado. Los resultados también indicaron que a baja presión de confinamiento, las muestras preparadas mediante un método de deposición húmedo, completan la licuefacción estática (ninguna presión de confinamiento efectiva y ninguna diferencia de estress). Los resultados indicaron también que a bajas presiones de confinamiento, los especímenes reconstituida por el método de deposición húmeda expuesto licuefacción estática completa (cero de la presión efectiva de confinamiento y cero diferencia de estrés). Como las presiones de confinamiento se incrementaron, las trayectorias de tensiones efectivas aumentaron la resistencia a la licuefacción, mostrando aumento de la tendencia dilatante

Vision-based techniques for gait recognition

Global security concerns have raised a proliferation of video surveillance devices. Intelligent surveillance systems seek to discover possible threats automatically and raise alerts. Being able to identify the surveyed object can help determine its threat level. The current generation of devices provide digital video data to be analysed for time varying features to assist in the identification process. Commonly, people queue up to access a facility and approach a video camera in full frontal view. In this environment, a variety of biometrics are available - for example, gait which includes temporal features like stride period. Gait can be measured unobtrusively at a distance. The video data will also include face features, which are short-range biometrics. In this way, one can combine biometrics naturally using one set of data. In this paper we survey current techniques of gait recognition and modelling with the environment in which the research was conducted. We also discuss in detail the issues arising from deriving gait data, such as perspective and occlusion effects, together with the associated computer vision challenges of reliable tracking of human movement. Then, after highlighting these issues and challenges related to gait processing, we proceed to discuss the frameworks combining gait with other biometrics. We then provide motivations for a novel paradigm in biometrics-based human recognition, i.e. the use of the fronto-normal view of gait as a far-range biometrics combined with biometrics operating at a near distance

On the Compensation for the Effects of Occlusion in Fronto-normal Gait Signal Processing

In surveillance applications, human gait data obtained from video contains idiosyncratic tendencies which allows it to be used as a biometric. This gait data has both time and image information. Expertise in the domain of time series analysis can be fruitfully employed in the image processing domain. In this paper, we consider the monocular frontal view of gait. En this view we track body parts to obtain time information and in doing so, complete occlusion of body parts may occur. To compensate for this, we present a novel standpoint where occluded images of objects may be considered as data missing from a time series. Thus we can consider this as a new application of the "missing data" problem studied in other fields dealing with time series data applied to the classic computer vision problem of occlusion. Using this approach, we consider three ways of compensating for occlusion - namely polynomial interpolation, autoregressive prediction and coupled time/frequency domain interpolation. We propose an experimental instantiation using a gait dataset and analyzing the motion of colored markers attached to body parts. The actual and predicted positions are compared which show our approach holds promise for complete occlusion compensation

Stochastic Norton-Simon-Massagu\ue9 Tumor Growth Modeling: Controlled and Mixed-Effects Uncontrolled Analysis

Tumorigenesis is a complex process that is heterogeneous and affected by numerous sources of variability. This study presents a stochastic extension of a biologically grounded tumor growth model, referred to as the Norton-Simon-Massagu\ue9 (NSM) tumor growth model. We first study the uncontrolled version of the model where the effect of chemotherapeutic drug agent is absent. Conditions on the model\u2019s parameters are derived to guarantee the positivity of the tumor volume and hence the validity of the proposed stochastic NSM model. To calibrate the proposed model we utilize a maximum likelihood- based estimation algorithm and population mixed-effect modeling formulation. The algorithm is tested by fitting previously published tumor volume mice data. Then, we study the controlled version of the model which includes the effect of chemotherapy treatment. Analysis of the influence of adding the control drug agent into the model and how sensitive it is to the stochastic parameters is performed both in open-loop and closed-loop viewpoints through different numerical simulations

Fig. 2. FP vs FN gait -physical dimensions needed for video capture Fig. 1. Left, view of typical security camera monitoring access point. Right, tracking multiple subjects On the Compensation for the Effects of Occlusion in Fronto-Normal Gait Signal Proc

Abstract -In surveillance applications, human gait data obtained from video contains idiosyncratic tendencies which allows it to be used as a biometric. This gait data has both time and image information. Expertise in the domain of time series analysis can be fruitfully employed in the image processing domain. In this paper, we consider the monocular frontal view of gait. In this view we track body parts to obtain time information and in doing so, complete occlusion of body parts may occur. To compensate for this, we present a novel standpoint where occluded images of objects may be considered as data missing from a time series. Thus we can consider this as a new application of the "missing data" problem studied in other fields dealing with time series data applied to the classic computer vision problem of occlusion. Using this approach, we consider three ways of compensating for occlusion -namely polynomial interpolation, autoregressive prediction and coupled time/frequency domain interpolation. We propose an experimental instantiation using a gait dataset and analyzing the motion of colored markers attached to body parts. The actual and predicted positions are compared which show our approach holds promise for complete occlusion compensation