Active control of time-varying broadband noise and vibrations using a sliding-window Kalman filter

Recently, a multiple-input/multiple-output Kalman filter technique was presented to control time-varying broadband noise and vibrations. By describing the feed-forward broadband active noise control problem in terms of a state estimation problem it was possible to achieve a faster rate of convergence than instantaneousgradient least-mean-squares algorithms and possibly also a better tracking performance. A multiple input/ multiple output Kalman algorithm was derived to perform this state estimation. To make the algorithm more suitable for real-time applications, the Kalman filter was written in a fast array form and the secondary path state matrices were implemented in output normal form. The resulting filter implementation was verified in simulations and in real-time experiments. It was found that for a constant primary path the filter had a fast rate of convergence and was able to track time-varying spectra. For a forgetting factor equal to unity the system was robust but the filter was unable to track rapid changes in the primary path. A forgetting factor lower than unity gave a significantly improved tracking performance but led to a numerical instability for the fast array form of the algorithm. To improve the numerical behavior, while enabling fast tracking and convergence, several variants are described in this paper. Results will be shown for a sliding window Recursive Least Squares filter in fast array form, which will later be extended to a full Kalman filter implementation by taking into account the uncertainty of the secondary path between the control sources and the error sensors. Multiple variants will be discussed in this paper. The first variant is the standard sliding window technique, which applies both updates and downdates to the filter coefficients. The second variant is an algorithm which only applies an update step to the filter coefficients and interprets the downdate step as an addition of a covariance matrix to the Riccati equation. The third variant uses an implicit forgetting factor. These implementations use a factorized form of the hyperbolic orthogonal transformation matrix. The different techniques will be applied to measured data of noise in houses near the runway of an airport. Results are given of the performance regarding tracking, convergence and numerical stability of the algorithms

Tracking and convergence of multi-channel Kalman filters for active noise control

The feed-forward broadband active noise control problem can be formulated as a state estimation problem to achieve a faster rate of convergence than the filtered reference least mean squares algorithm and possibly also a better tracking performance. A multiple input/multiple output Kalman algorithm is used to perform this state estimation. To make the algorithm more suitable for real-time applications the Kalman filter is written in a fast array form and the secondary path state matrices are implemented in output normal form. The implementation was tested in simulations and in real-time experiments. It was found that for a constant primary path the Kalman filter has a fast rate of convergence and is able to track changes in the spectrum. For a forgetting factor equal to unity the system is robust, but the filter is unable to track rapid changes in the primary path. It is shown that a forgetting factor lower than unity gives a significantly improved tracking performance. Numerical issues of the fast array form of the algorithm for such forgetting factors are discussed and possible solutions are presented

Real-time Kalman filter implementation for active feedforward control of time-varying broadband noise and vibrations

Tracking behavior and the rate of convergence are critical properties in active noise control applications with time-varying disturbance spectra. As compared to the standard filtered-reference Least Mean Square (LMS) algorithm, improved convergence can be obtained with schemes based on preconditioning, affine projections, Recursive Least Squares (RLS), and other methods. The RLS method potentially leads to very fast convergence but straightforward implementations may suffer from round-off errors and suboptimal tracking behavior. In this paper a Kalman filter approach is used which, as compared to RLS, includes a covariance weighting for model output errors in order to improve tracking behavior and robustness. An orthogonal transformation scheme was used to reduce the influence for round-off errors of the Kalman recursions. In this paper an extension is given for multiple input multiple output systems, and results of a real-time implementation are presented. Conclusions are given regarding the suitability for real-time implementation of previous formulations. Different parameterizations of the secondary path model between the active control source and the error sensor are compared. Real-time results demonstrate the rapid convergence for reduction of noise in a duct, as well as numerical stability during extended operation intervals.status: publishe

Application of virtual sensors in three-dimensional broadband active noise control and the effects on the quiet zones

This paper presents various experimental results of a real-time, multiple-channel, broadband Active Noise Control (ANC) system, employing the Remote Microphone Technique (RMT) as virtual sensing algorithm in different settings. The effects of virtual sensing on the shape and size of the quiet zone are experimentally investigated. To enhance the quiet zone, an acoustic energy density probe can be used as error sensor. Such a sensor not only measures sound pressure, but also the particle velocity in three directions, providing four signals to be minimized by the ANC system. The RMT is used to construct a virtual three dimensional, acoustic energy density probe, which is validated in real-time ANC. In conclusion, advantages, drawbacks and practical considerations of using RMT virtual sensing in active noise control are discussed

Advances and visions in large-scale hydrological modelling: findings from the 11th Workshop on Large-Scale Hydrological Modelling

Large-scale hydrological modelling has become increasingly wide-spread during the last decade. An annual workshop series on large-scale hydrological modelling has provided, since 1997, a forum to the German-speaking community for discussing recent developments and achievements in this research area. In this paper we present the findings from the 2007 workshop which focused on advances and visions in large-scale hydrological modelling. We identify the state of the art, difficulties and research perspectives with respect to the themes "sensitivity of model results", "integrated modelling" and "coupling of processes in hydrosphere, atmosphere and biosphere". Some achievements in large-scale hydrological modelling during the last ten years are presented together with a selection of remaining challenges for the future

Molecular epidemiologic investigations of Mycoplasma gallisepticum conjunctivitis in songbirds by random amplified polymorphic DNA analyses.

An ongoing outbreak of conjunctivitis in free-ranging house finches (Carpodacus mexicanus) began in 1994 in the eastern United States. Bacterial organisms identified as Mycoplasma gallisepticum (MG) were isolated from lesions of infected birds. MG was also isolated from a blue jay (Cyanocitta cristata) that contracted conjunctivitis after being housed in a cage previously occupied by house finches with conjunctivitis, and from free-ranging American goldfinches (Carduelis tristis) in North Carolina in 1996. To investigate the molecular epidemiology of this outbreak, we produced DNA fingerprints of MG isolates by random amplification of polymorphic DNA (RAPD). We compared MG isolates from songbirds examined from 1994 through 1996 in 11 states, representing three host species, with vaccine and reference strains and with contemporary MG isolates from commercial poultry. All MG isolates from songbirds had RAPD banding patterns identical to each other but different from other strains and isolates tested. These results indicate that the outbreak of MG in songbirds is caused by the same strain, which suggests a single source; the outbreak is not caused by the vaccine or reference strains analyzed; and MG infection has not been shared between songbirds and commercial poultry

Building an integrated modeling framework for assessing land-use change and its consequences for areal water balance in mountainous Southwest China

The opening up of China's industry towards market orientation has a distinct impact on natural resources as well as on social structures. The example of rubber introduction in Yunnan province (SW China) shows the mutual interdependencies between economy, natural resources, and social structures. We assess the impacts of rubber introduction and possible development paths in the study area. An integrated modeling framework (NabanFrame) is developed for the catchment of the Naban River (size 270 km2), a tributary to the Mekong River. NabanFrame comprises an agro-economic, ecological, and social model. Altogether they interact with a land-use change model via defined interfaces. Effects on the water cycle are considered by additionally integrating the spatially distributed rainfall-runoff and water balance model AKWA-M® in the model framework. Therefore, a reasonable parameterization is needed to assess the land-use changes on areal water fluxes. The authors conclude that the chosen hydrological model is able to assess the impacts of land conversion (from forest to rubber plantations) on catchment hydrology and address further adaptations to be implemented in the hydrological model.BMBF/LILA

Effect of Neoadjuvant Chemotherapy Followed by Surgical Resection on Survival in Patients With Limited Metastatic Gastric or Gastroesophageal Junction Cancer: The AIO-FLOT3 Trial

IMPORTANCE: Surgical resection has a potential benefit for patients with metastatic adenocarcinoma of the stomach and gastroesophageal junction. OBJECTIVE: To evaluate outcome in patients with limited metastatic disease who receive chemotherapy first and proceed to surgical resection. DESIGN, SETTING, AND PARTICIPANTS: The AIO-FLOT3 (Arbeitsgemeinschaft Internistische Onkologie-fluorouracil, leucovorin, oxaliplatin, and docetaxel) trial is a prospective, phase 2 trial of 252 patients with resectable or metastatic gastric or gastroesophageal junction adenocarcinoma. Patients were enrolled from 52 cancer care centers in Germany between February 1, 2009, and January 31, 2010, and stratified to 1 of 3 groups: resectable (arm A), limited metastatic (arm B), or extensive metastatic (arm C). Data cutoff was January 2012, and the analysis was performed in March 2013. INTERVENTIONS: Patients in arm A received 4 preoperative cycles of fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT) followed by surgery and 4 postoperative cycles. Patients in arm B received at least 4 cycles of neoadjuvant FLOT and proceeded to surgical resection if restaging (using computed tomography and magnetic resonance imaging) showed a chance of margin-free (R0) resection of the primary tumor and at least a macroscopic complete resection of the metastatic lesions. Patients in arm C were offered FLOT chemotherapy and surgery only if required for palliation. Patients received a median (range) of 8 (1-15) cycles of FLOT. MAIN OUTCOMES AND MEASURES: The primary end point was overall survival. RESULTS: In total, 238 of 252 patients (94.4%) were eligible to participate. The median (range) age of participants was 66 (36-79) years in arm A (n = 51), 63 (28-79) years in arm B (n = 60), and 65 (23-83) years in arm C (n = 127). Patients in arm B (n = 60) had only retroperitoneal lymph node involvement (27 patients [45%]), liver involvement (11 [18.3%]), lung involvement (10 [16.7%]), localized peritoneal involvement (4 [6.7%]), or other (8 [13.3%]) incurable sites. Median overall survival was 22.9 months (95% CI, 16.5 to upper level not achieved) for arm B, compared with 10.7 months (95% CI, 9.1-12.8) for arm C (hazard ratio, 0.37; 95% CI, 0.25-0.55) (P < .001). The response rate for arm B was 60% (complete, 10%; partial, 50%), which is higher than the 43.3% for arm C. In arm B, 36 of 60 patients (60%) proceeded to surgery. The median overall survival was 31.3 months (95% CI, 18.9-upper level not achieved) for patients who proceeded to surgery and 15.9 months (95% CI, 7.1-22.9) for the other patients. CONCLUSIONS AND RELEVANCE: Patients with limited metastatic disease who received neoadjuvant chemotherapy and proceeded to surgery showed a favorable survival. The AIO-FLOT3 trial provides a rationale for further randomized clinical trials. TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT00849615.info:eu-repo/semantics/publishedVersio

HLA Class I Binding 9mer Peptides from Influenza A Virus Induce CD4+ T Cell Responses

BACKGROUND: Identification of human leukocyte antigen class I (HLA-I) restricted cytotoxic T cell (CTL) epitopes from influenza virus is of importance for the development of new effective peptide-based vaccines. METHODOLOGY/PRINCIPAL FINDINGS: In the present work, bioinformatics was used to predict 9mer peptides derived from available influenza A viral proteins with binding affinity for at least one of the 12 HLA-I supertypes. The predicted peptides were then selected in a way that ensured maximal coverage of the available influenza A strains. One hundred and thirty one peptides were synthesized and their binding affinities for the HLA-I supertypes were measured in a biochemical assay. Influenza-specific T cell responses towards the peptides were quantified using IFNgamma ELISPOT assays with peripheral blood mononuclear cells (PBMC) from adult healthy HLA-I typed donors as responder cells. Of the 131 peptides, 21 were found to induce T cell responses in 19 donors. In the ELISPOT assay, five peptides induced responses that could be totally blocked by the pan-specific anti-HLA-I antibody W6/32, whereas 15 peptides induced responses that could be completely blocked in the presence of the pan-specific anti-HLA class II (HLA-II) antibody IVA12. Blocking of HLA-II subtype reactivity revealed that 8 and 6 peptide responses were blocked by anti-HLA-DR and -DP antibodies, respectively. Peptide reactivity of PBMC depleted of CD4(+) or CD8(+) T cells prior to the ELISPOT culture revealed that effectors are either CD4(+) (the majority of reactivities) or CD8(+) T cells, never a mixture of these subsets. Three of the peptides, recognized by CD4(+) T cells showed binding to recombinant DRA1*0101/DRB1*0401 or DRA1*0101/DRB5*0101 molecules in a recently developed biochemical assay. CONCLUSIONS/SIGNIFICANCE: HLA-I binding 9mer influenza virus-derived peptides induce in many cases CD4(+) T cell responses restricted by HLA-II molecules

Fatal Cases of Influenza A(H3N2) in Children: Insights from Whole Genome Sequence Analysis

During the Northern Hemisphere winter of 2003–2004 the emergence of a novel influenza antigenic variant, A/Fujian/411/2002-like(H3N2), was associated with an unusually high number of fatalities in children. Seventeen fatal cases in the UK were laboratory confirmed for Fujian/411-like viruses. To look for phylogenetic patterns and genetic markers that might be associated with increased virulence, sequencing and phylogenetic analysis of the whole genomes of 63 viruses isolated from fatal cases and non fatal “control” cases was undertaken. The analysis revealed the circulation of two main genetic groups, I and II, both of which contained viruses from fatal cases. No associated amino acid substitutions could be linked with an exclusive or higher occurrence in fatal cases. The Fujian/411-like viruses in genetic groups I and II completely displaced other A(H3N2) viruses, but they disappeared after 2004. This study shows that two A(H3N2) virus genotypes circulated exclusively during the winter of 2003–2004 in the UK and caused an unusually high number of deaths in children. Host factors related to immune state and differences in genetic background between patients may also play important roles in determining the outcome of an influenza infection