Matched direction detectors

In this paper, we address the problem of detecting a signal whose associated spatial signature is subject to uncertainties, in the presence of subspace interference and broadband noise, and using multiple snapshots from an array of sensors. To account for steering vector uncertainties, we assume that the spatial signature of interest lies in a given linear subspace H while its coordinates in this subspace are unknown. The generalized likelihood ratio test (GLRT) for the problem at hand is formulated. We show that the GLRT amounts to searching for the best direction in the subspace H after projecting out the interferences. The distribution of the GRLT under both hypotheses is derived and numerical simulations illustrate its performance

Matched direction detectors and estimators for array processing with subspace steering vector uncertainties

In this paper, we consider the problem of estimating and detecting a signal whose associated spatial signature is known to lie in a given linear subspace but whose coordinates in this subspace are otherwise unknown, in the presence of subspace interference and broad-band noise. This situation arises when, on one hand, there exist uncertainties about the steering vector but, on the other hand, some knowledge about the steering vector errors is available. First, we derive the maximum-likelihood estimator (MLE) for the problem and compute the corresponding Cramer-Rao bound. Next, the maximum-likelihood estimates are used to derive a generalized likelihood ratio test (GLRT). The GLRT is compared and contrasted with the standard matched subspace detectors. The performances of the estimators and detectors are illustrated by means of numerical simulations

Critical Care's move to fund open access

SCOPUS: ed.jinfo:eu-repo/semantics/publishe

Inter-sensor propagation delay estimation using sources of opportunity

Propagation delays are intensively used for Structural Health Monitoring or Sensor Network Localization. In this paper, we study the performances of acoustic propagation delay estimation between two sensors, using sources of opportunity only. Such sources are defined as being uncontrolled by the user (activation time, location, spectral content in time and space), thus preventing the direct estimation with classical active approaches, such as TDOA, RSSI and AOA. Observation models are extended from the literature to account for the spectral characteristics of the sources in this passive context and we show how time-filtered sources of opportunity impact the retrieval of the propagation delay between two sensors. A geometrical analogy is then proposed that leads to a lower bound on the variance of the propagation delay estimation that accounts for both the temporal and the spatial properties of the sources field

Effects of category management on producer-retailer relationships

The relationships between retailers and producers are considered for understanding the determinants of quality, variety and prices. In the food sector, some issues have been extensively studied: impacts of private labels, supply contracts, price transmission. Despite an increasing role, the implementation of “Category management” (CM) has been less studied. CM belongs to a set of methods based on the concepts of Efficient Consumer Response and Supply Chain Management which have been widely implemented by large retailers and thus have changed the relationships among actors in the food chain. As a part of this evolution, Category Captain’s concept (CC) involves a commitment between a retailer and one of the suppliers who receives decision-making power over the product category. Usually, the major of the food suppliers plays the CC’s role in partnership with the retailers. In practices, CC raises many questions. What effects on the sales and prices? Is it beneficial for all the stakeholders, including the consumers? What are their consequences on the non captain suppliers? We propose a vertical relationship model considering that the retailer is the chain’s leader (Stackelberg game). We compare a non-cooperative game (no CC) to a cooperative game (one supplier as CC). We analyse under which conditions CC improves the profit of each stakeholder, as well as the consumers’ surplus. We show that the cooperative game is always a “win, win, win” game for stakeholders (but not necessary for consumers) if the two suppliers offer similar products. If products are different, we define the parameters relationships under which CC is beneficial for stakeholders and consumers.Category captain, shelf space allocation, game theory, Stackelberg equilibrium., Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety,

Steroids in sepsis: another swing of the pendulum in our clinical trials

Many studies have been conducted to try and find interventions to treat patients with severe sepsis, but with little success. In several cases, initial apparent beneficial effects have not been confirmed in later trials. The story of steroids in sepsis is one example of this pendulum effect, with initial success in the study by Annane et al. tempered by the more recent negative results of the Corticus study. The reasons for this pendulum effect are likely related, at least in part, to issues of clinical trial design and the way in which clinical trials in intensive care unit patients are developed, conducted and assessed needs to be critically reassessed