The Experts below are selected from a list of 3327 Experts worldwide ranked by ideXlab platform
Michael G Apte - One of the best experts on this subject based on the ideXlab platform.
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air Filter materials outdoor ozone and building related symptoms in the base study
Indoor Air, 2008Co-Authors: I S H Buchanan, Mark J Mendell, Anna G Mirer, Michael G ApteAbstract:UNLABELLED Used ventilation air Filters have been shown to reduce indoor environmental quality and worker performance and increase symptoms, with effects stronger after reaction of Filters with ozone. We analyzed data from the US EPA Building Assessment Survey and Evaluation (BASE) study to determine if ozone and specific Filter media have interactive effects on building-related symptoms (BRS). We analyzed a subset of 34 buildings from the BASE study of 100 US office buildings to determine the separate and joint associations of Filter medium [polyester/synthetic (PS) or fiberglass (FG)] and outdoor ozone concentration (above/below the median, 67.6 microg/m(3)) with BRS. Using logistic regression models and general estimating equations, we estimated odds ratios (ORs) and 95% confidence intervals for the association of Filter medium, ozone, and Filter medium x ozone with BRS. Relative to FG + low ozone, PS alone or high ozone alone, were each significantly (P < 0.05) associated only with fatigue/difficulty concentrating (ORs = 1.93 and 1.54, respectively). However, joint exposure to both PS + high ozone, relative to FG + low ozone, had significant associations with lower and upper respiratory, cough, eye, fatigue, and headache BRS (ORs ranged from 2.26 to 5.90). Joint ORs for PS + high ozone for lower and upper respiratory and headache BRS were much greater than multiplicative, with interaction P-values <0.10. Attributable risk proportion (ARP) estimates indicate that removing both risk factors might, given certain assumptions, reduce BRS by 26-62%. These findings suggest possible adverse health consequences from chemical interactions between outdoor ozone and PS Filters in buildings. Results need confirmation before recommending changes in building operation. However, if additional research confirms Causal relationships, ARP estimates indicate that appropriate Filter selection may substantially reduce BRS in buildings, especially in high-ozone areas. PRACTICAL IMPLICATIONS The results indicate that a better understanding of how Filters interact with their environment is needed. While the mechanism is unknown and these findings need to be replicated, they indicate that the joint risk of BRS from polyester/synthetic Filters and outdoor ozone above 67.6 microg/m(3) is much greater than the risk from each alone. These findings suggest potential reductions in BRS from appropriate selection of ventilation Filter media or implementing strategies to reduce ozone entrained in building ventilation systems. If the relationships were found to be Causal, Filter replacement and ozone abatement should be undertaken.
Kochi Kieko - One of the best experts on this subject based on the ideXlab platform.
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Linear Causal Filtering: definition and theory
'Cold Spring Harbor Laboratory', 2021Co-Authors: Pascual-marqui, Roberto D, Biscay, Rolando J, Bosch-bayard Jorge, Achermann Peter, Faber Pascal, Kinoshita Toshihiko, Kochi KiekoAbstract:This work provides a framework based on multivariate autoregressive modeling for linear Causal Filtering in the sense of Granger. In its bivariate form, the linear Causal Filter defined here takes as input signals A and B, and it Filters out the Causal effect of B on A, thus yielding two new signals only containing the Granger-Causal effect of A on B. In its general multivariate form for more than two signals, the effect of all indirect Causal connections between A and B, mediated by all other signals, are accounted for, partialled out, and Filtered out also. The importance of this Filter is that it enables the estimation of directional measures of Causal information flow from any non-Causal, non-directional measure of association. For instance, based on the classic coherence, a directional measure of strength of information flow from A to B is obtained when applied to the linear Causal Filtered pair containing only A to B connectivity information. This particular case is equivalent to the isolated effective coherence (doi.org/10.3389/fnhum.2014.00448). Of more recent interest are the large family of phase-phase, phase-amplitude, and amplitude-amplitude cross-frequency coupling measures which are non-directional. The linear Causal Filter makes it now possible to estimate the directional Causal versions these measures of association. One important field of application is in brain connectivity analysis based on cortical signals of electric neuronal activity (e.g. estimated sources of EEG and MEG, and invasive intracranial ECoG recordings). The linear Causal Filter introduced here provides a novel solution to the problem of estimating the direction of information flow from any non-directional measure of association. This work provides definitions, non-ambiguous equations, and clear prescriptions for implementing the linear Causal Filter in diverse settings
Yuan Xiuhua - One of the best experts on this subject based on the ideXlab platform.
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performance analysis of the reception based on least mean square adaptive algorithm in optical wireless communication system
Chinese Journal of Lasers, 2006Co-Authors: Yuan XiuhuaAbstract:Optical wireless communication(OWC) systems use the atmosphere as a propagation medium,so the atmospheric turbulence effects lead to multiplicative noise related with signal intensity.In order to suppress the signal fading induced by multiplicative noise,the decision threshold-updating algorithm based on least-mean-square(LMS) adaptive Filter is introduced and investigated.An accurate expression for the steady-state tap-weight covariance matrix is derived for the real LMS algorithm.The effect of the parameters in LMS algorithm on OWC system performance was introduced through theoretical analysis and computer simulation.It is shown that in the OWC system with non-Causal Filter the turbulence effect has been apparently abated.The bit error ratio(BER) of the system over weak turbulence based on adaptive Filter is below 10~(-8),which can satisfy the communication requirement.The 255 order non-Causal structure of LMS Filter is the optimal structure.
I. Suresh - One of the best experts on this subject based on the ideXlab platform.
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A simple estimation of equatorial Pacific response from windstress to untangle Indian Ocean Dipole and Basin influences on El Niño
Climate Dynamics, 2016Co-Authors: T. Izumo, J. Vialard, H. Dayan, M. Lengaigne, I. SureshAbstract:Sea Surface Temperature (SST) anomalies that develop in spring in the central Pacific are crucial to the El Niño Southern Oscillation (ENSO) development. Here we use a linear, continuously stratified, ocean model, and its impulse response to a typical ENSO wind pattern, to derive a simple equation that relates those SST anomalies to the low frequency evolution of zonal wind stress anomalies τ _ x over the preceding months. We show that SST anomalies can be approximated as a “Causal” Filter of τ _ x , τ _ x ( t − t _1) − c τ _ x ( t − t _2), where t_1 is ~1–2 months, t_2 − t_1 is ~6 months and c ranges between 0 and 1 depending on τ _ x location (i.e. SST anomalies are approximately proportional to the wind stress anomalies 1–2 months earlier minus a fraction of the wind stress anomalies 7–8 months earlier). The first term represents the fast oceanic response, while the second one represents the delayed negative feedback associated with wave reflection at both boundaries. This simple approach is then applied to assess the relative influence of the Indian Ocean Dipole (IOD) and of the Indian Ocean Basin-wide warming/cooling (IOB) in favouring the phase transition of ENSO. In agreement with previous studies, Atmospheric General Circulation Model experiments indicate that the equatorial Pacific wind responses to the IOD eastern and (IOB-related) western poles tend to cancel out during autumn. The abrupt demise of the IOD eastern pole thus favours an abrupt development of the IOB-cooling-forced westerly wind anomalies in the western Pacific in winter–spring (vice versa for an IOB warming). As expected from the simple SST equation above, the faster wind change fostered by the IOD enhances the central Pacific SST response as compared to the sole IOB influence. The IOD thereby enhances the IOB tendency to favour ENSO phase transition. As the IOD is more independent of ENSO than the IOB, this external influence could contribute to enhanced ENSO predictability.
Ruan Huai-lin - One of the best experts on this subject based on the ideXlab platform.
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Non-Causal Digital Cancellation in Simultaneous Transmission and Reception Technology
MATEC Web of Conferences, 2018Co-Authors: Sun Bing, Ruan Huai-linAbstract:The electronic system occasionally requires the simultaneous transmission and reception of signals in the same platform. In the circumstance of simultaneous transmission and reception, the strong coupling interference signal cancellation requires shorter data and better cancellation effectiveness, but the cancellation performance of general Causal canceller is relatively poor. Motivated by this, adopting non-Causal Filter to realize digital cancellation is then proposed in the paper. The model of non-Causal Filter digital cancellation is built at first, and the digital cancellation is simulated and analysed. The simulation results demonstrate that the digital cancellation has outstanding characteristics, and at the same time, the results also indicate that in the circumstance of the same Filter order, the non-Causal Filter digital cancellation has better cancellation effectiveness.