Many distributed applications demand the underlying distributed systems to accommodate their needs. Matching requirements of distributed applications compels the prompt identification of momentary characteristics of an underlying distributed system. Thus, a method is needed to promptly derive a momentary state of a distributed system by identifying a set of events occurred across hosts and occu...

Event detection for context inconsistency is challenging in pervasive computing environments, where contexts are often noisy owing to fragile connectivity, node frequent movement and resource constraints. As a recent scheme, CEDA — Concurrent Event Detection for Asynchronous inconsistency checking (CEDA) — concurrently detects context inconsistency by exploring the happened-before relation amon...

Aims. An unbiased and detailed characterization of the galaxy luminosity function (LF) is a basic requirement in many astrophysical issues: it is of particular interest in assessing the role of the environment in the evolution of the LF of different galaxy types. Methods. We studied the evolution in the B band LF to redshift z ∼ 1 in the zCOSMOS 10k sample, for which both accurate galaxy classi...

Causal broadcasting has been introduced to reduce the asynchrony of communication channels inside groups of processes. It states that if two broadcast messages are causally related by the happened-before relation, these messages are delivered in their sending order to each process of the group. Even though protocols implementing causal broadcasting do not add control messages, they suuer from t...

The age of the Universe depends on both the present-day Hubble Constant and on the history of cosmic expansion. For decelerating cosmologies such as Ω m = 1, the dimensionless product H 0 t 0 < 1 and modestly high values of the Hubble constant H 0 > 70 would be inconsistent with a cosmic age t 0 larger than 12 Gyr. But if Ω Λ > 0, then H 0 t 0 can take on a range of values. Evidence from the Hu...

This paper presents a general framework for tracking the time differences of arrivals of multiple acoustic sources recorded by distributed microphone pairs. Tracking is based on a three-stage analysis. Complex-valued propagation models are extracted at different time instants and frequencies using either the independent component analysis or the phase of the cross-power spectrum evaluated at ea...

In detection and target tracking applications, low-observable targets are defined as those that deliver measurements for which the sensor responses have a value of SNR lower than 10dB. Tracking of low-observable targets is best performed employing the approaches known as trackbefore-detect (TBD). The proper TBD approaches combine signal processing and tracking so that detection and track confir...

We will be closely following the book ”Essentials of Stochastic Processes”, 2nd Edition, by Richard Durrett, for the topic ‘Finite Discrete time Markov Chains’ (FDTM). These preliminary notes are for giving an overview, and for providing some guidance on what to aim at while studying this topic. An FDTM has a finite number of states on which it can rest at discrete times 1, 2, · · · . Usually t...

Blind localization and tracking of mobile terminals in urban scenarios is an important requirement for offering new locationbased services, handling emergency cases of nonsubscribed users, public safety, countering IEDs, and so forth. In this context, we propose a track-before-detect scheme taking explicitly advantage of multipath propagation in an urban terrain by using a priori information ab...

In this paper, we address the problem of detecting and tracking targets with a low signal-to-noise ratio (SNR) by exploiting hybrid differential evolution (HDE) in the particle filter track-before-detect (PF-TBD) context. Firstly, we introduce the Bayesian PF-TBD method and its weaknesses. Secondly, the HDE algorithm is regarded as a novel particle updating strategy, which is proposed to optimi...