scholarly journals On the Procedure of Draught Rate Assessment in Indoor Spaces

2020 ◽  
Vol 10 (15) ◽  
pp. 5036
Author(s):  
Detelin Markov ◽  
Nikolay Ivanov ◽  
George Pichurov ◽  
Marina Zasimova ◽  
Peter Stankov ◽  
...  
Keyword(s):  
Thermal Environment ◽  
Low Frequency ◽  
High Amplitude ◽  
Time Interval ◽  
Cfd Simulations ◽  
Reliable Assessment ◽  
Unsteady Rans ◽  
Computational Fluid Dynamics Cfd ◽  
Indoor Spaces

The objective of the paper is to demonstrate the importance of the unsteady Computational Fluid Dynamics (CFD) simulations and long-term measurements for the reliable assessment of thermal comfort indoors, for proper categorization of the indoor thermal environment and for identifying the reasons for complaints due to draught discomfort. Numerical simulations and experimental measurements were applied in combination to study ventilation in a field laboratory, a university classroom with a controlled indoor environment. Strong unsteadiness of the airflow was registered both in the unsteady RANS results and the real-scale long-term velocity data measured with thermo anemometer. Low-frequency high-amplitude velocity fluctuations observed lead to substantial time variation of the draught rate. In case of categorization of a thermal environment, the point measurements or steady-state RANS computations would lead to wrong conclusions as well as they cannot be used for identification of the reasons for people’s complaints due to draught discomfort if strong unsteadiness of the airflow exists. It is demonstrated that the length of the time interval for draught rate (DR) assessment may not be universal if low-frequency high-amplitude pulsations are present in the room airflow.

Electrical Resistive Spiking of Fungi

2021 ◽  
pp. 1-7 ◽  
Author(s):  
Andrew Adamatzky ◽  
Alessandro Chiolerio ◽  
Georgios Sirakoulis
Keyword(s):  
Electrical Resistance ◽  
Electronic Devices ◽  
Low Frequency ◽  
High Amplitude ◽  
Average Amplitude ◽  
Average Width ◽  
C 23 ◽  
C 30 ◽  
Low Amplitude

We study long-term electrical resistance dynamics in mycelium and fruit bodies of oyster fungi P. ostreatus. A nearly homogeneous sheet of mycelium on the surface of a growth substrate exhibits trains of resistance spikes. The average width of spikes is c. 23[Formula: see text]min and the average amplitude is c. 1[Formula: see text]k[Formula: see text]. The distance between neighboring spikes in a train of spikes is c. 30[Formula: see text]min. Typically, there are 4–6 spikes in a train of spikes. Two types of electrical resistance spikes trains are found in fruit bodies: low frequency and high amplitude (28[Formula: see text]min spike width, 1.6[Formula: see text]k[Formula: see text] amplitude, 57[Formula: see text]min distance between spikes) and high frequency and low amplitude (10[Formula: see text]min width, 0.6[Formula: see text]k[Formula: see text] amplitude, 44[Formula: see text]min distance between spikes). The findings could be applied in monitoring of physiological states of fungi and future development of living electronic devices and sensors.

Managing Nonrandomly Varying Fisheries

1989 ◽  
Vol 46 (8) ◽  
pp. 1302-1308 ◽  
Author(s):  
J. Anthony Koslow
Keyword(s):  
Environmental Variability ◽  
Low Frequency ◽  
High Amplitude ◽  
Fish Population ◽  
Environmental Forcing ◽  
Fish Yield ◽  
Recruitment Variability ◽  
Age Structured ◽  
Constant Escapement

Theoretical studies indicate that constant effort or constant escapement harvest strategies are viable long-term management policies for fisheries influenced by random environmental variability. But the marine environment and fishery recruitment do not characteristically vary randomly: their time series tend to be autocorrelated. I examined the response of a model of an age-structured fish population to these harvest strategies, if recruitment is influenced by periodic variability. Variance in fish yield and the incidence of low stock size increased with both increasing amplitude and period length of environmental forcing. Sensitivity to environmental fluctuations increased sharply at periodicities between one and several times the generation length. Low-risk fisheries, which are subject to little nonrandom recruitment variability, may be satisfactorily managed by either management strategy, although constant effort harvesting provided greater stability to industry with little risk to the fish population. Neither strategy maintained stability in high-risk fisheries with high-amplitude, low-frequency recruitment variability, but a constant escapement policy minimized risk of stock collapse.

scholarly journals 2411

2017 ◽  
Vol 1 (S1) ◽  
pp. 65-65 ◽  
Author(s):  
Nakesha King ◽  
Victoria Pepper ◽  
Cameron Best ◽  
Ekene Onwuka ◽  
Chengyu Li ◽  
...  
Keyword(s):  
Respiratory Symptoms ◽  
Three Dimensional ◽  
Large Animal Model ◽  
Large Animal ◽  
Promising Technique ◽  
Cfd Simulations ◽  
Life Saving ◽  
Study Population ◽  
Computational Fluid Dynamics Cfd

OBJECTIVES/SPECIFIC AIMS: Tissue engineered tracheal grafts (TETG) could provide a life-saving cure for children with long segment airway defects. Computational fluid dynamics (CFD) is a novel and promising technique used to evaluate TETG performance. This pilot study examines the correlation of objective CFD simulations with subjective respiratory symptoms in a TETG large animal model. METHODS/STUDY POPULATION: Three-dimensional geometries of 1 TETG implanted sheep trachea were reconstructed from serial fluoroscopic images, allowing analysis with CFD simulations. Peak flow velocity (PFV) and peak wall shear stress (PWSS) across the graft as well as changes secondary to stenting were determined. CFD metrics were compared with respiratory symptoms seen on exam. RESULTS/ANTICIPATED RESULTS: Two weeks after implantation, the animal developed respiratory distress, which correlated with PFV and PWSS elevations. Although the intraluminal graft appearance changed minimally after dilation, PFV and PWSS decreased across the graft (4.5–0.8 m/s and 0.9–0.1 Pa, respectively). Long-term TETG stenting with dilation returned PFV and PWSS to baseline (0.8–0.3 m/s and 0.1–0.01 Pa, respectively), which correlated with immediate symptom resolution. DISCUSSION/SIGNIFICANCE OF IMPACT: CFD is a noninvasive modality, which allows the evaluation of airflow metrics of symptomatic TETG recipients. This diagnostic tool will permit planned interventions and graft design optimization.

scholarly journals A 2-decade (1988–2009) record of diatom fluxes in the Mauritanian coastal upwelling: impact of low-frequency forcing and a two-step shift in the species composition

2021 ◽  
Vol 18 (5) ◽  
pp. 1873-1891
Author(s):  
Oscar E. Romero ◽  
Simon Ramondenc ◽  
Gerhard Fischer
Keyword(s):  
Coastal Waters ◽  
Temporal Dynamics ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Meridional Overturning Circulation ◽  
Benthic Diatoms ◽  
Time Interval ◽  
Data Set ◽  
The Impact

Abstract. Eastern boundary upwelling ecosystems (EBUEs) are among the most productive marine regions in the world's oceans. Understanding the degree of interannual to decadal variability in the Mauritania upwelling system is crucial for the prediction of future changes of primary productivity and carbon sequestration in the Canary Current EBUE as well as in similar environments. A multiyear sediment trap experiment was conducted at the mooring site CBmeso (“Cape Blanc mesotrophic”, ca. 20∘ N, ca. 20∘40′ W) in the highly productive coastal waters off Mauritania. Here, we present results on fluxes of diatoms and the species-specific composition of the assemblage for the time interval between March 1988 and June 2009. The temporal dynamics of diatom populations allows the proposal of three main intervals: (i) early 1988–late 1996, (ii) 1997–1999, and (iii) early 2002–mid 2009. The Atlantic Multidecadal Oscillation (AMO) appears to be an important driver of the long-term dynamics of diatom population. The long-term AMO-driven trend is interrupted by the occurrence of the strong 1997 El Niño–Southern Oscillation (ENSO). The extraordinary shift in the relative abundance of benthic diatoms in May 2002 suggests the strengthening of offshore advective transport within the uppermost layer of filament waters and in the subsurface and in deeper and bottom-near layers. It is hypothesized that the dominance of benthic diatoms was the response of the diatom community to the intensification of the slope and shelf poleward undercurrents. This dominance followed the intensification of the warm phase of AMO and the associated changes of the Atlantic Meridional Overturning Circulation. Transported valves (siliceous remains) from shallow Mauritanian coastal waters into the bathypelagic should be considered for the calculation and model experiments of bathy- and pelagic nutrients budgets (especially Si), the burial of diatoms, and the paleoenvironmental signal preserved in downcore sediments. Additionally, our 1988–2009 data set contributes to the characterization of the impact of low-frequency climate forcings in the northeastern Atlantic and will be especially helpful for establishing the scientific basis for forecasting and modeling future states of the Canary Current EBUE and its decadal changes.

scholarly journals Low-frequency lower E-region wind and reflection height measurements as sensor for climate variability

2008 ◽  
Vol 6 ◽  
pp. 331-335 ◽  
Author(s):  
C. Jacobi
Keyword(s):  
Oblique Incidence ◽  
Lower Thermosphere ◽  
Low Frequency ◽  
Time Interval ◽  
Radio Waves ◽  
Reflection Height ◽  
E Region ◽  
Long Term Trends ◽  
Mlt Region

Abstract. Measurements of reflection heights of low-frequency (LF) radio waves at oblique incidence and estimates of mesosphere/lower thermosphere (MLT) region horizontal winds applying the D1 spaced receiver method on LF field strength registrations are analyzed with respect to possible long-term trends and interdecadal variability in the time interval from ~1980 to date. While no clear signal of mesospheric height trend is registered during the last two decades, significant trends of MLT horizontal winds are found. These trends are non-linear, in particular a change of trends around 1990 is found, which is probably connected with changes in tropospheric and stratospheric conditions at that time.

scholarly journals Study on Cross-Ventilation Performance of Residences in the Passive Town Kurobe Model Based on Measurements and CFD

2019 ◽  
Vol 111 ◽  
pp. 06055
Author(s):  
Yoju Homma ◽  
Takashi Kurabuchi
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Thermal Environment ◽  
Sufficient Accuracy ◽  
Cfd Simulations ◽  
Downstream Side ◽  
Indoor Thermal Environment ◽  
Computational Fluid Dynamics Cfd ◽  
Housing Complex ◽  
Ventilation Performance

The housing complex in the Passive Town Kurobe model was designed for residents to enjoy an environmentally-friendly lifestyle, and cross-ventilation was used to improve indoor thermal environment in hot seasons. To understand and maximize environmental improvements through cross-ventilation, computational fluid dynamics (CFD) simulations and measurements were carried out. It was confirmed that CFD simulation using the modified k-å model reproduced the observations with sufficient accuracy. The turbulence model used in the CFD simulations in this study was the standard k-å model, which incorporates the Durbin limiter. This model had the most accurate correspondence with the measured values. The wind catcher (WC) used to increase the cross-ventilation flow rate was found to be ineffective in the dominant wind direction. Further, it was found that if the room targeted for environmental improvement was on the upstream/downstream side, the flow rate was maximized if all windows in the room were opened.

scholarly journals Long-Term Effect of Low-Frequency Electromagnetic Irradiation in Water and Isotonic Aqueous Solutions as Studied by Photoluminescence from Polymer Membrane

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1443
Author(s):  
Nikolai F. Bunkin ◽  
Polina N. Bolotskova ◽  
Elena V. Bondarchuk ◽  
Valery G. Gryaznov ◽  
Sergey V. Gudkov ◽  
...  
Keyword(s):  
Low Frequency ◽  
Polymer Membrane ◽  
Deionized Water ◽  
Time Interval ◽  
Platinum Electrodes ◽  
Electromagnetic Treatment ◽  
Long Term Effect ◽  
Surface Liquid ◽  
Reference Samples

The swelling of a polymer membrane NafionTM in deionized water and isotonic NaCl and Ringer’s solutions was studied by photoluminescent spectroscopy. According to our previous studies, the surface of this membrane could be considered as a model for a cellular surface. Liquid samples, in which the membrane was soaked, were subjected to preliminary electromagnetic treatment, which consisted of irradiating these samples with electric rectangular pulses of 1 µs duration using platinum electrodes immersed in the liquid. We used a series of pulses with a repetition rate of 11–125 Hz; the pulse amplitudes were equal to 100 and 500 mV. It turned out that at certain pulse repetition rates and their amplitudes, the characteristic swelling time of the polymer membrane significantly differs from the swelling time in untreated (reference) samples. At the same time, there is no effect for certain frequencies/pulse amplitudes. The time interval between electromagnetic treatment and measurements was about 20 min. Thus, in our experiments the effects associated with the long-term relaxation of liquids on the electromagnetic processing are manifested. The effect of long-term relaxation could be associated with a slight change in the geometric characteristics of bubston clusters during electromagnetic treatment.

APPLICATION OF THE EMPIRICAL MODE DECOMPOSITION METHOD TO GROUND-ROLL NOISE ATTENUATION IN SEISMIC DATA

2013 ◽  
Vol 31 (4) ◽  
pp. 619 ◽  
Author(s):  
Luiz Eduardo Soares Ferreira ◽  
Milton José Porsani ◽  
Michelângelo G. Da Silva ◽  
Giovani Lopes Vasconcelos
Keyword(s):  
Empirical Mode Decomposition ◽  
Seismic Data ◽  
Low Frequency ◽  
High Amplitude ◽  
Seismic Line ◽  
Seismic Processing ◽  
Mode Decomposition ◽  
Ground Roll ◽  
Fortran 90 ◽  
Emd Method

ABSTRACT. Seismic processing aims to provide an adequate image of the subsurface geology. During seismic processing, the filtering of signals considered noise is of utmost importance. Among these signals is the surface rolling noise, better known as ground-roll. Ground-roll occurs mainly in land seismic data, masking reflections, and this roll has the following main features: high amplitude, low frequency and low speed. The attenuation of this noise is generally performed through so-called conventional methods using 1-D or 2-D frequency filters in the fk domain. This study uses the empirical mode decomposition (EMD) method for ground-roll attenuation. The EMD method was implemented in the programming language FORTRAN 90 and applied in the time and frequency domains. The application of this method to the processing of land seismic line 204-RL-247 in Tacutu Basin resulted in stacked seismic sections that were of similar or sometimes better quality compared with those obtained using the fk and high-pass filtering methods.Keywords: seismic processing, empirical mode decomposition, seismic data filtering, ground-roll. RESUMO. O processamento sísmico tem como principal objetivo fornecer uma imagem adequada da geologia da subsuperfície. Nas etapas do processamento sísmico a filtragem de sinais considerados como ruídos é de fundamental importância. Dentre esses ruídos encontramos o ruído de rolamento superficial, mais conhecido como ground-roll . O ground-roll ocorre principalmente em dados sísmicos terrestres, mascarando as reflexões e possui como principais características: alta amplitude, baixa frequência e baixa velocidade. A atenuação desse ruído é geralmente realizada através de métodos de filtragem ditos convencionais, que utilizam filtros de frequência 1D ou filtro 2D no domínio fk. Este trabalho utiliza o método de Decomposição em Modos Empíricos (DME) para a atenuação do ground-roll. O método DME foi implementado em linguagem de programação FORTRAN 90, e foi aplicado no domínio do tempo e da frequência. Sua aplicação no processamento da linha sísmica terrestre 204-RL-247 da Bacia do Tacutu gerou como resultados, seções sísmicas empilhadas de qualidade semelhante e por vezes melhor, quando comparadas as obtidas com os métodos de filtragem fk e passa-alta.Palavras-chave: processamento sísmico, decomposição em modos empíricos, filtragem dados sísmicos, atenuação do ground-roll.

Long Term Effects of Low Frequency (10 Hz) Vagus Nerve Stimulation on EEG and Heart Rate Variability in Crohn's Disease: A Case Report

2014 ◽  
Vol 7 (6) ◽  
pp. 914-916 ◽  
Author(s):  
Didier Clarençon ◽  
Sonia Pellissier ◽  
Valérie Sinniger ◽  
Astrid Kibleur ◽  
Dominique Hoffman ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Crohn’S Disease ◽  
Case Report ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Vagus Nerve Stimulation ◽  
Low Frequency ◽  
Long Term Effects
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