Search results for "Parametric"
showing 10 items of 980 documents
Adaptive Stochastic Airline Seat Inventory Control under Parametric Uncertainty
2013
Airline seat inventory control is a very profitable tool in the airline industry. The problem of adaptive stochastic airline seat inventory control lies at the heart of airline revenue management. This problem concerns the allocation of the finite seat inventory to the stochastic customer demand that occurs over time before the flight is scheduled to depart. The objective is to find the right combination of customers of various fare classes on the flight such that revenue is maximized. In this paper, the static and dynamic policies of stochastic airline seat inventory control (airline booking) are developed under parametric uncertainty of underlying models, which are not necessarily alterna…
Improvement of Inventory Control under Parametric Uncertainty and Constraints
2011
The aim of the present paper is to show how the statistical inference equivalence principle (SIEP), the idea of which belongs to the authors, may be employed in the particular case of finding the effective statistical decisions for the multi-product inventory problems with constraints. To our knowledge, no analytical or efficient numerical method for finding the optimal policies under parametric uncertainty for the multi-product inventory problems with constraints has been reported in the literature. Using the (equivalent) predictive distributions, this paper represents an extension of analytical results obtained for unconstrained optimization under parametric uncertainty to the case of con…
A non-parametric segmentation methodology for oral videocapillaroscopic images
2014
We aim to describe a new non-parametric methodology to support the clinician during the diagnostic process of oral videocapillaroscopy to evaluate peripheral microcirculation. Our methodology, mainly based on wavelet analysis and mathematical morphology to preprocess the images, segments them by minimizing the within-class luminosity variance of both capillaries and background. Experiments were carried out on a set of real microphotographs to validate this approach versus handmade segmentations provided by physicians. By using a leave-one-patient-out approach, we pointed out that our methodology is robust, according to precision-recall criteria (average precision and recall are equal to 0.9…
Interspecific associations among larval helminths in fish
2001
Various processes can generate associations between the larvae of different helminth species in their fish intermediate or paratenic host. We investigated the pairwise associations among larval helminth species in eight different fish populations, using two different coefficients of associations, in order to determine in what situations they are strongest. All helminth species included use the fish studied as either their second intermediate host or their paratenic host, and are acquired by the fish when it ingests an infected first intermediate host. The intensity of infection correlated positively with fish length for most helminth species. Pairs of species which both exhibited positive c…
Minimum Leading Edge Protection Application Length to Combat Rain-Induced Erosion of Wind Turbine Blades
2021
Leading edge erosion (LEE) repairs of wind turbine blades (WTBs) involve infield application of leading edge protection (LEP) solutions. The industry is currently aiming to use factory based LEP coatings that can applied to the WTBs before they are shipped out for installation. However, one of the main challenges related to these solutions is the choice of a minimum LEP application length to be applied in the spanwise direction of the WTBs. Generally, coating suppliers apply 10–20 m of LEP onto the blades starting from the tip of the blade using the “rule of thumb”, and no studies in the literature exist that stipulate how these LEP lengths can be calculated. In this study, we extend the sc…
Monte Carlo simulation in phylogenies: an application to test the constancy of evolutionary rates.
1994
Monte Carlo simulation has commonly been used in phylogenetic studies to test different tree-reconstruction methods, and consequently, its application for testing evolutionary models can be considered as a natural extension of this usage. Repetitive simulation of a given evolutionary process, under the restrictions imposed by the model to be tested, along a determinate tree topology allow the estimate of probability distributions for the desired parameters. Next, the phylogenetic tree can be reconstructed again without the constraints of the model, and the parameter of interest, derived from this tree, can be compared to the corresponding probability distribution derived from the restricted…
Response Correlations of Linear Systems with White Noise Linearly Parametric Inputs
1996
Relationships between moments and correlations of the response of linear systems subjected to linearly parametric normal white noise inputs are here reported. They are obtained by extensively using the properties of the stochastic integral calculus.
Therapeutic management and evolution of chronic hepatitis B: does HIV still have an impact? The EPIB 2012 study
2015
EA Pôle MERS Hors CT hors EJ; International audience; Background & Aims: To compare the management of chronic hepatitis B (CHB) and its evolution over time in currently followed HIV-positive and HIV-negative patients. Methods: A total of 709 consecutive patients with past or present positive HBs antigenemia seen in October 2012 in 19 French participating centres were included. The data were retrospectively collected from the first visit onwards through standardized questionnaires. Results: Chronic hepatitis B was less often assessed in the 299 HIV-positive patients, who were older, more likely to be male, excessive alcohol drinkers and HBe antigen-, HCV- and HDV-positive. They were also fol…
Hepatocellular Carcinoma Presenting at Contrast-Enhanced Multi–Detector-Row Computed Tomography or Gadolinium-Enhanced Magnetic Resonance Imaging as …
2012
OBJECTIVE: The objective of the study was to measure growth rate and to determine the optimal interval time for imaging follow-up of hepatocellular carcinomas (HCCs) presenting at multi-detector-row computed tomography (MDCT) or magnetic resonance imaging (MRI) as small, indeterminate lesions. METHODS: We included patients with cirrhosis with HCC initially presenting as indeterminate lesion of 2 cm or less at MDCT or MRI August 2005 to August 2009 and with available imaging follow-up. Measures of tumor growth included tumor volume doubling time (TVDT), tumor percentual diameter increase, and tumor percentual volume increase. RESULTS: We examined 48 patients (mean age, 64 years) with 69 HCCs…
Prognostic indicators of successful endoscopic sclerotherapy for prevention of rebleeding from oesophageal varices in cirrhosis: a long-term cohort s…
2000
Abstract Background. Although band ligation is now recommended for prevention of rebleeding from oesophageal varices in cirrhosis, sclerotherapy is still widely used. Patients submitted to chronic sclerotherapy undergo several endoscopies and experience a large number of serious complications. However, long-term outcome is poorly defined. Aims. To assess the clinical course and prognostic indicators of patients undergoing chronic sclerotherapy for prevention of variceal rebleeding as a basis for future evaluation of long-term band ligation outcome. Methods. Prospective cohort study prognostic analysis by the Cox proportional hazards model. Results. A total of 218 consecutive cirrhotic patie…