6,319 research outputs found
Interacting Multiple Model-Feedback Particle Filter for Stochastic Hybrid Systems
In this paper, a novel feedback control-based particle filter algorithm for
the continuous-time stochastic hybrid system estimation problem is presented.
This particle filter is referred to as the interacting multiple model-feedback
particle filter (IMM-FPF), and is based on the recently developed feedback
particle filter. The IMM-FPF is comprised of a series of parallel FPFs, one for
each discrete mode, and an exact filter recursion for the mode association
probability. The proposed IMM-FPF represents a generalization of the
Kalmanfilter based IMM algorithm to the general nonlinear filtering problem.
The remarkable conclusion of this paper is that the IMM-FPF algorithm retains
the innovation error-based feedback structure even for the nonlinear problem.
The interaction/merging process is also handled via a control-based approach.
The theoretical results are illustrated with the aid of a numerical example
problem for a maneuvering target tracking application
Viscous vortical flow calculations over delta wings
Two approaches to calculate turbulent vortical flows over delta wing configurations are illustrated. The first is for a simple delta wing at low speeds using the boundary layer approximation to treat the effects of the secondary separation. The second is for the supersonic case of a generic fighter using the NASA Ames parabolized Navier/Stokes method. Test/theory comparisons are given in both cases
R.F. planar magnetron sputtered ZnO films II: Electrical properties
The electrical properties of r.f. planar magnetron sputtered ZnO films are studied by means of current-voltage, capacitance-voltage and Van der Pauw measurements.\ud
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These films are applied as piezoelectric transducers in micromechanical sensors and actuators. Their piezoelectric behaviour strongly depends on the electric properties.\ud
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A conduction model for the polycrystalline ZnO layers is presented. This model gives a good description of the electrical behaviour, and is useful in understanding the piezoelectric properties of the films studied
Transmission Power Measurements for Wireless Sensor Nodes and their Relationship to the Battery Level
In this work we focus on the new generation EYESIFXv2 [1] wireless sensor nodes by carrying out experimental measurements on power related quantities. In particular, our aim is to characterize the relationship between the level of the battery and the transmission power radiated by the node. The present results point out the non linear and non trivial effects due to the output potentiometer which can be used to tune the transmission power. It shall be observed that a thorough study of how battery and/or potentiometer settings translate to actual transmitted power levels is crucial to e.g. design correct power control algorithms, which can effectively operate under any operational condition of the wireless sensor device
Interviewer Effects on Nonresponse
In face-to-face surveys interviewers play a crucial role in making contact with and gaining cooperation from sample units. While some analyses investigate the influence of interviewers on nonresponse, they are typically restricted to single-country studies. However, interviewer training, contacting and cooperation strategies as well as survey climates may differ across countries. Combining call-record data from the European Social Survey (ESS) with data from a detailed interviewer questionnaire on attitudes and doorstep behavior we find systematic country differences in nonresponse processes, which can in part be explained by differences in interviewer characteristics, such as contacting strategies and avowed doorstep behavior.
Gene loss and lineage specific restriction-modification systems associated with niche differentiation in the Campylobacter jejuni Sequence Type 403 clonal complex
Campylobacter jejuni is a highly diverse species of bacteria commonly associated with infectious intestinal disease of humans and zoonotic carriage in poultry, cattle, pigs, and other animals. The species contains a large number of distinct clonal complexes that vary from host generalist lineages commonly found in poultry, livestock, and human disease cases to host-adapted specialized lineages primarily associated with livestock or poultry. Here, we present novel data on the ST403 clonal complex of C. jejuni, a lineage that has not been reported in avian hosts. Our data show that the lineage exhibits a distinctive pattern of intralineage recombination that is accompanied by the presence of lineage-specific restriction-modification systems. Furthermore, we show that the ST403 complex has undergone gene decay at a number of loci. Our data provide a putative link between the lack of association with avian hosts of C. jejuni ST403 and both gene gain and gene loss through nonsense mutations in coding sequences of genes, resulting in pseudogene formation
On the Nature of MeV-blazars
Broad-band spectra of the FSRQ (flat-spectrum-radio quasars) detected in the
high energy gamma-ray band imply that there may be two types of such objects:
those with steep gamma-ray spectra, hereafter called MeV-blazars, and those
with flat gamma-ray spectra, GeV-blazars. We demonstrate that this difference
can be explained in the context of the ERC (external-radiation-Compton) model
using the same electron injection function. A satisfactory unification is
reachable, provided that: (a) spectra of GeV-blazars are produced by internal
shocks formed at the distances where cooling of relativistic electrons in a jet
is dominated by Comptonization of broad emission lines, whereas spectra of
MeV-blazars are produced at the distances where cooling of relativistic
electrons is dominated by Comptonization of near-IR radiation from hot dust;
(b) electrons are accelerated via a two step process and their injection
function takes the form of a double power-law, with the break corresponding to
the threshold energy for the diffusive shock acceleration. Direct predictions
of our model are that, on average, variability time scales of the MeV-blazars
should be longer than variability time scales of the GeV-blazars, and that both
types of the blazar phenomenon can appear in the same object.Comment: Accepted for publication in the Astrophysical Journa
Measuring Interviewer Characteristics Pertinent to Social Surveys: A Conceptual Framework
Interviewer effects are found across all types of interviewer-mediated surveys crossing disciplines and countries. While studies describing interviewer effects are manifold, identifying characteristics explaining these effects has proven difficult due to a lack of data on the interviewers. This paper proposes a conceptual framework of interviewer characteristics for explaining interviewer effects and its operationalization in an interviewer questionnaire. The framework encompasses four dimensions of interviewer characteristics: interviewer attitudes, interviewers’ own behaviour, interviewers’ experience with measurements, and interviewers’ expectations. Our analyses of the data collected from interviewers working on the fourth wave of SHARE Germany show that the above measures distinguish well between interviewers
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