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71.
Kretowski M Rolland Y Bézy-Wendling J Coatrieux JL 《IEEE transactions on medical imaging》2003,22(2):248-257
In this paper, a model-based approach to medical image analysis is presented. It is aimed at understanding the influence of the physiological (related to tissue) and physical (related to image modality) processes underlying the image content. This methodology is exemplified by modeling first, the liver and its vascular network, and second, the standard computed tomography (CT) scan acquisition. After a brief survey on vascular modeling literature, a new method, aimed at the generation of growing three-dimensional vascular structures perfusing the tissue, is described. A solution is proposed in order to avoid intersections among vessels belonging to arterial and/or venous trees, which are physiologically connected. Then it is shown how the propagation of contrast material leads to simulate time-dependent sequences of enhanced liver CT slices. 相似文献
72.
In the classical framework of formal languages, a refinement operation is modeled by a substitution and an abstraction by
an inverse substitution. These mechanisms have been widely studied, because they describe a change in the specification level,
from an abstract view to a more concrete one, or conversely. For timed systems, there is up to now no uniform notion of substitution.
In this paper, we study timed substitutions in the general framework of signal-event languages, where both signals and events
are taken into account. We prove that regular signal-event languages are closed under substitution and inverse substitution.
To obtain these results, we use in a crucial way a “well known” result: regular signal-event languages are closed under intersection.
In fact, while this result is indeed easy for languages defined by Alur and Dill’s timed automata, it turns out that the construction
is much more tricky when considering the most involved model of signal-event automata. We give here a construction working
on finite and infinite signal-event words and taking into account signal stuttering, unobservability of zero-duration τ-signals and Zeno runs. Note that if several constructions have been proposed in particular cases, it is the first time that
a general construction is provided. 相似文献
73.
In this paper, we define the notion of approximate bisimulation relation between two continuous systems. While exact bisimulation requires that the observations of two systems are and remain identical, approximate bisimulation allows the observations to be different provided the distance between them remains bounded by some parameter called precision. Approximate bisimulation relations are conveniently defined as level sets of a so-called bisimulation function which can be characterized using Lyapunov-like differential inequalities. For a class of constrained linear systems, we develop computationally effective characterizations of bisimulation functions that can be interpreted in terms of linear matrix inequalities and optimal values of static games. We derive a method to evaluate the precision of the approximate bisimulation relation between a constrained linear system and its projection. This method has been implemented in a Matlab toolbox: MATISSE. An example of use of the toolbox in the context of safety verification is shown. 相似文献
74.
No?l Xavier; Bechara Antoine; Dan Bernard; Hanak Catherine; Verbanck Paul 《Canadian Metallurgical Quarterly》2007,21(6):778
Individuals with alcoholism exhibit poor decision making as reflected by their continued alcohol use despite encountering problems and by low performance in laboratory tasks of decision making. Here, the authors investigated the relative contribution of several distinct processes of executive functions in performance on the Iowa Gambling Task (IGT; A. Bechara, A. R. Damasio, H. Damasio, & S. W. Anderson, 1994) in recently detoxified individuals with alcoholism. Compared to matched healthy participants, individuals with alcoholism showed below-normal scores in the last 20 trials of the IGT as well as on other tasks of executive functions, specifically those assessing the capacity to manipulate information stored in working memory, detect abstract rules, or inhibit prepotent responses. Prepotent response inhibition best predicted performance in the late trials of the IGT, that is, when participants have likely acquired knowledge about the reward/punishment contingencies of the task. These results underline the important role that response inhibition plays in decision making, especially in risky situations, when knowledge of the probability of a given outcome becomes available (i.e. decisions under risk). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
Antoine Le Mortellec Joffrey Clarhaut Yves Sallez Thierry Berger Damien Trentesaux 《Engineering Applications of Artificial Intelligence》2013,26(1):227-240
The use of electronic equipment and embedded computing technologies in modern complex transportation systems continues to grow in a highly competitive market, in which product maintainability and availability is vital. These technological advances also make fault diagnosis and maintenance interventions much more challenging, since these operations require a deep understanding of the entire system. This paper proposes a holonic cooperative fault diagnosis approach, along with a generic architecture, to increase the embedded diagnosis capabilities of complex transportation systems. This concept is applied to the fault diagnosis of door systems of a railway transportation system. 相似文献
76.
77.
We propose a variant of the recently introduced strategy for stabilisation with limited information by D. Liberzon and J.P. Hespanha and analyse its robustness properties. We show that, if the nominal plant can be made input-to-state stable with respect to measurement errors, parameter uncertainty and exogenous disturbances, then this robustness is preserved with this quantised feedback. More precisely, if a sufficient bandwidth is available on the communication network, then the resulting closed loop is shown to be semiglobally input-to-state practically stable. 相似文献
78.
K. Servat S. Tingry L. Brunel S. Querelle M. Cretin C. Innocent C. Jolivalt M. Rolland 《Journal of Applied Electrochemistry》2007,37(1):121-127
Enzyme biocatalyst assemblies on electrode surfaces can be used to construct efficient membrane-less biofuel cells. The present
study reports on the construction of biocatalytic oxygen electrodes based on the modification of porous carbon tubes with
laccase and 2,2′-azinobis-(3-ethylbenzothiazoline−6-sulfonate) (ABTS2−) as mediator, co-immobilized within electrochemically polymerized films. Porous carbon tubes are used as original conducting
support for enzyme incorporation and for the transport of dissolved dioxygen solution via diffusive flow through the porosity.
The activity of the laccase immobilized on the porous carbon support is determined. Performance of the biocathodes towards
the reduction of dioxygen to water is demonstrated by chronoamperometry at +0.4 V vs. Ag/AgCl in citrate/phosphate buffer
pH 3. Moreover, the current–voltage behaviour of the biocathodes show high current densities at pH 3 (a current peak equal
to 280 μA cm−2 for the biocathode based on both entrapped laccase and mediator) and a low oxygen reduction overvoltage compared to platinum
electrode. 相似文献
79.
Daniel B. Reeves Morgane Rolland Bethany L. Dearlove Yifan Li Merlin L. Robb Joshua T. Schiffer Peter Gilbert E. Fabian Cardozo-Ojeda Bryan T. Mayer 《Journal of the Royal Society Interface》2021,18(179)
Clinical trials for HIV prevention can require knowledge of infection times to subsequently determine protective drug levels. Yet, infection timing is difficult when study visits are sparse. Using population nonlinear mixed-effects (pNLME) statistical inference and viral loads from 46 RV217 study participants, we developed a relatively simple HIV primary infection model that achieved an excellent fit to all data. We also discovered that Aptima assay values from the study strongly correlated with viral loads, enabling imputation of very early viral loads for 28/46 participants. Estimated times between infecting exposures and first positives were generally longer than prior estimates (average of two weeks) and were robust to missing viral upslope data. On simulated data, we found that tighter sampling before diagnosis improved estimation more than tighter sampling after diagnosis. Sampling weekly before and monthly after diagnosis was a pragmatic design for good timing accuracy. Our pNLME timing approach is widely applicable to other infections with existing mathematical models. The present model could be used to simulate future HIV trials and may help estimate protective thresholds from the recently completed antibody-mediated prevention trials. 相似文献
80.
The initial fretting damage in a glass/PMMA contact was investigated by means of experiments and numerical (F.E.M.) simulations. Both micro-crack nucleation at the contact edges and particle detachment were identified on the PMMA's surface. Micro-crack initiation was related to the combination of high tensile stresses and positive hydrostatic pressures which are known to enhance crazing. During the early stages of the fretting tests, the distribution of the detached particles within the contact was correlated to the spatial distribution of the cumulative interfacial energy dissipated by friction. As the number of cycles was increased, it was observed that detached particles moved toward the middle of the contact. On the basis of FEM simulations, this particle displacement within the contact was attributed to the existence of differential micro-displacements during the fretting cycle. 相似文献