scholarly journals Spatial interference between infectious hotspots: epidemic condensation and optimal windspeed

2021 ◽  
pp. 2150044
Author(s):  
Johannes Dieplinger ◽  
Sauro Succi
Keyword(s):  
Wind Speed ◽  
Equation Of State ◽  
Beneficial Effect ◽  
Spatial Correlation ◽  
Local Minimum ◽  
Local Maximum ◽  
Peak Intensity ◽  
Spatial Interference ◽  
Relative Infectivity ◽  
Inverse Distance

We discuss the effects of spatial interference between two infectious hotspots as a function of the mobility of individuals (wind speed) between the two and their relative degree of infectivity. As long as the upstream hotspot is less contagious than the downstream one, increasing the wind speed leads to a monotonic decrease of the infection peak in the downstream hotspot. Once the upstream hotspot becomes about between twice and five times more infectious than the downstream one, an optimal wind speed emerges, whereby a local minimum peak intensity is attained in the downstream hotspot, along with a local maximum beyond which the beneficial effect of the wind is restored. Since this nonmonotonic trend is reminiscent of the equation of state of nonideal fluids, we dub the above phenomena “epidemic condensation”. When the relative infectivity of the upstream hotspot exceeds about a factor five, the beneficial effect of the wind above the optimal speed is completely lost: any wind speed above the optimal one leads to a higher infection peak. It is also found that spatial correlation between the two hotspots decay much more slowly than their inverse distance. It is hoped that the above findings may offer a qualitative clue for optimal confinement policies between different cities and urban agglomerates.

Multi-step real-time wind speed prediction based on convolution memory network

2021 ◽  
pp. 0309524X2199826
Author(s):  
Guowei Cai ◽  
Yuqing Yang ◽  
Chao Pan ◽  
Dian Wang ◽  
Fengjiao Yu ◽  
...  
Keyword(s):  
Feature Extraction ◽  
Wind Speed ◽  
Real Time ◽  
Wind Power ◽  
Spatial Correlation ◽  
Prediction Accuracy ◽  
Spatial Information ◽  
Spatial Association ◽  
Spatial Feature ◽  
Time Prediction

Multi-step real-time prediction based on the spatial correlation of wind speed is a research hotspot for large-scale wind power grid integration, and this paper proposes a multi-location multi-step wind speed combination prediction method based on the spatial correlation of wind speed. The correlation coefficients were determined by gray relational analysis for each turbine in the wind farm. Based on this, timing-control spatial association optimization is used for optimization and scheduling, obtaining spatial information on the typical turbine and its neighborhood information. This spatial information is reconstructed to improve the efficiency of spatial feature extraction. The reconstructed spatio-temporal information is input into a convolutional neural network with memory cells. Spatial feature extraction and multi-step real-time prediction are carried out, avoiding the problem of missing information affecting prediction accuracy. The method is innovative in terms of both efficiency and accuracy, and the prediction accuracy and generalization ability of the proposed method is verified by predicting wind speed and wind power for different wind farms.

Carrier Concentrations and Drift Currents in the Depletion Region of a p–n Junction

2003 ◽  
Vol 10 (04) ◽  
pp. 649-660
Author(s):  
D. K. Mak
Keyword(s):  
Solid State ◽  
Applied Voltage ◽  
Local Minimum ◽  
Local Maximum ◽  
Depletion Region ◽  
Electron Drift ◽  
Electron Carrier ◽  
Quantitative Explanation ◽  
State Device ◽  
Solid State Device

It has always been stated in electronics, semiconductor and solid state device textbooks that the hole drift and electron drift currents in the depletion region of a p–n junction are constant and independent of applied voltage (biasing). However, the explanations given are qualitative and unclear. We extrapolate the existing analytic theory of a p–n junction to give a quantitative explanation of why the currents are constant. We have also shown that the carrier concentrations in the depletion region, as depicted in some of the textbooks, are incorrect, and need to be revised. Our calculations further demonstrate that in reverse biasing, both hole and electron carrier concentrations each experience a local maximum and a local minimum, indicating that their diffusion currents change directions twice within the depletion region.

Diffusivity dependence of multiple-breath washouts of lung periphery

1990 ◽  
Vol 68 (1) ◽  
pp. 76-83 ◽  
Author(s):  
G. G. Berdine ◽  
D. Dale ◽  
J. E. Johnson ◽  
J. L. Lehr
Keyword(s):  
Tidal Volume ◽  
Exponential Decay ◽  
Local Minimum ◽  
Local Maximum ◽  
Inspiratory Flow ◽  
Normal Range ◽  
Lung Periphery ◽  
Kinetics Of ◽  
And Diffusion ◽  
Single Exponential

Subpleural concentrations of He and SF6 were measured during multiple-breath washouts from isolated dog lungs. Tidal volume, inspiratory flow, and frequency were in the normal range of canine ventilation. For each gas, there was a local minimum in concentration during inspiration (Cinsp) and a local maximum in concentration during exhalation (Cexp). SF6 exhibited a deeper inspiratory trough than He for each breath of every washout. For large tidal volumes (10-20 ml/kg), Cexp approximated a single exponential decay and He was cleared more rapidly than SF6. For small tidal volumes (2.5 ml/kg), Cexp was multiexponential and SF6 was cleared more rapidly than He. Cinsp/Cexp (a measure of the depth of the inspiratory trough) and the kinetics of Cexp decay were determined for washouts using a tidal volume of 10 and 20 ml/kg and different inspiratory flows. Under all conditions, an increase of inspiratory flow resulted in a deeper inspiratory trough for both He and SF6. For washouts using 10 ml/kg and 60 breaths/min, an increase of inspiratory flow increased the clearance of both gases. In washouts using lower ventilatory frequencies, gas clearance was independent of inspiratory flow. These findings are contrary to predictions of contemporary models of convection and diffusion in the lung. This study suggests that convective axial mixing and radial diffusion in the airways are important determinants of pulmonary gas transport.

scholarly journals σ-Holes vs. Buildups of Electronic Density on the Extensions of Bonds to Halogen Atoms

Inorganics ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 71 ◽  
Author(s):  
Peter Politzer ◽  
Jane S. Murray
Keyword(s):  
Electrostatic Potential ◽  
Local Minimum ◽  
Halogen Atom ◽  
Local Maximum ◽  
Outer Side ◽  
Electronic Density ◽  
Halogen Atoms ◽  
Positive Electrostatic Potential

Our discussion focuses upon three possible features that a bonded halogen atom may exhibit on its outer side, on the extension of the bond. These are (1) a region of lower electronic density (a σ-hole) accompanied by a positive electrostatic potential with a local maximum, (2) a region of lower electronic density (a σ-hole) accompanied by a negative electrostatic potential that also has a local maximum, and (3) a buildup of electronic density accompanied by a negative electrostatic potential that has a local minimum. In the last case, there is no σ-hole. We show that for diatomic halides and halogen-substituted hydrides, the signs and magnitudes of these maxima and minima can be expressed quite well in terms of the differences in the electronegativities of the halogen atoms and their bonding partners, and the polarizabilities of both. We suggest that the buildup of electronic density and absence of a σ-hole on the extension of the bond to the halogen may be an operational indication of ionicity.

scholarly journals OSCILLATING INSTANTONS AS HOMOGENEOUS TUNNELING CHANNELS

2013 ◽  
Vol 28 (18) ◽  
pp. 1350082 ◽  
Author(s):  
BUM-HOON LEE ◽  
WONWOO LEE ◽  
DONG-HAN YEOM
Keyword(s):  
Scalar Field ◽  
Local Minimum ◽  
Local Maximum ◽  
Einstein Gravity ◽  
Scale Factor ◽  
The Other ◽  
Vacuum Decay ◽  
General Vacuum

In this paper, we study Einstein gravity with a minimally coupled scalar field accompanied with a potential, assuming an O(4) symmetric metric ansatz. We call an Euclidean instanton is to be an oscillating instanton, if there exists a point where the derivative of the scale factor and the scalar field vanish at the same time. Then, we can prove that the oscillating instanton can be analytically continued, both as inhomogeneous and homogeneous tunneling channels. Here, we especially focus on the possibility of a homogeneous tunneling channel. For the existence of such an instanton, we have to assume three things: (1) there should be a local maximum and the curvature of the maximum should be sufficiently large, (2) there should be a local minimum and (3) the other side of the potential should have a sufficiently deeper vacuum. Then, we can show that there exists a number of oscillating instanton solutions and their probabilities are higher compared to the Hawking–Moss instantons. We also check the possibility when the oscillating instantons are comparable with the Coleman–de Luccia channels. Thus, for a general vacuum decay problem, we should not ignore the oscillating instanton channels.

scholarly journals Spatial correlation of marine wind‐speed observations

1988 ◽  
Vol 26 (4) ◽  
pp. 524-540 ◽  
Author(s):  
R.D. Brown ◽  
V.R. Swail
Keyword(s):  
Wind Speed ◽  
Spatial Correlation

scholarly journals Observation and Simulation of Wind Speed and Wind Power Density over Bac Lieu Region

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Hiep Van Nguyen ◽  
Pham Xuan Thanh ◽  
Nguyen Duc Nam ◽  
Nguyen Xuan Anh ◽  
Pham Le Khuong ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Power Density ◽  
Bias Correction ◽  
Local Maximum ◽  
Observation Data ◽  
Wind Power Density ◽  
Wind Speeds ◽  
Diurnal Cycles ◽  
Southern Vietnam

In this study, the WRF (Weather Research and Forecasting) model was used to simulate and investigate diurnal and annual variations of wind speed and wind power density over Southern Vietnam at 2‐km horizontal resolution for two years (2016 and 2017). The model initial and boundary conditions are from the National Centers for Environmental Prediction (NCEP) Final Analyses (FNL). Observation data for two years at 20 m height at Bac Lieu station were used for model bias correction and investigating diurnal and annual variation of wind speeds. The results show that the WRF model overestimates wind speeds. After bias correction, the model reasonably well simulates wind speeds over the research area. Wind speed and wind power density show much higher values at levels of 50–200 m above ground levels than near ground (20 m) level and significantly higher near the coastal regions than inland. Wind speed has significant annual and diurnal cycles. Both annual and diurnal cycles of wind speeds were well simulated by the model. Wind speed is much stronger during daytime than at nighttime. Low-level wind speed reaches the maximum at about 14 LT to 15 LT when the vertical momentum mixing is highly active. Wind speeds over the eastern coastal region of Southern Vietnam are much stronger in winter than in summer due to two main reasons, including (1) stronger large-scale wind speed in winter than in summer and (2) funnel effect creating a local maximum wind speed over the nearshore ocean which then transports high-momentum air inland in winter.

A more conclusive and more inclusive second derivative test

2020 ◽  
Vol 104 (560) ◽  
pp. 247-254
Author(s):  
Ronald Skurnick ◽  
Christopher Roethel
Keyword(s):  
Critical Point ◽  
Critical Points ◽  
Local Minimum ◽  
Local Maximum ◽  
Number Line ◽  
Second Derivative ◽  
First Derivative ◽  
Line Test ◽  
First Derivative Test ◽  
Derivative Test

Given a differentiable function f with argument x, its critical points are those values of x, if any, in its domain for which either f′ (x) = 0 or f′ (x) is undefined. The first derivative test is a number line test that tells us, definitively, whether a given critical point, x = c, of f(x) is a local maximum, a local minimum, or neither. The second derivative test is not a number line test, but can also be applied to classify the critical points of f(x). Unfortunately, the second derivative test is, under certain conditions, inconclusive.

On the Optimal Control Problem With Unrestricted Final Time

1969 ◽  
Vol 91 (2) ◽  
pp. 155-160 ◽  
Author(s):  
C. T. Leondes ◽  
R. A. Niemann
Keyword(s):  
Optimal Control ◽  
Local Minimum ◽  
Computational Algorithm ◽  
Local Maximum ◽  
Fixed Time ◽  
Performance Criterion ◽  
Necessary Condition ◽  
Sufficient Condition ◽  
Final Time ◽  
Numerical Examples

In problems of optimal control, the final time T may be fixed or it may be unrestricted. For the unrestricted final time case, an additional necessary condition that the Hamiltonian be zero is added to the conditions for optimality used for the fixed time case. In this paper, it will be shown that this necessary condition may lead to a local maximum of the performance criterion with respect to final times as well as a local minimum. This paper first develops a computational algorithm using only the H = 0 condition, and then develops a sufficient condition for a local minimum with respect to final time and a computational algorithm employing this condition. Numerical examples are given to illustrate all results.

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