A STUDY OF TRANSATLANTIC RADIO PROPAGATION MODES AT 41.5 MC/S

1963 ◽  
Vol 41 (2) ◽  
pp. 220-233 ◽  
Author(s):  
E. L. Hagg ◽  
W. Rolfe
Keyword(s):  
Control Point ◽  
Signal Strength ◽  
Ground Level ◽  
Auroral Zone ◽  
Great Circle ◽  
Radio Propagation ◽  
Transmitted Power ◽  
Sound Channel ◽  
The North ◽  
Great Circle Path

Both great-circle and off-path propagation modes have been investigated on a transatlantic path. Measurements of signal strength and azimuthal bearing were made at Ottawa, Canada, on the 41.5-Mc/s BBC TV sound channel transmissions during the winter months of 1957–58. The predominant signal was found to be a ground (land or sea) sidescatter signal arriving about 35° to the south of the great circle path. The presence of this signal can be explained qualitatively by ground-level focusing near the intersection of the receiver and transmitter skip distances.A secondary off-path signal, arriving about 7° to the north of the great circle path, was observed. This signal may be ionospheric sidescatter from irregularities in the auroral zone. It is suggested that the ionospheric sidescatter is analogous to ground sidescatter since focusing is not restricted to ground level.It is shown that the method using the two-hop geometric great circle path is superior to the 2000-km control-point method for predicting monthly median transatlantic maximum usable frequencies during winter daytime when low to moderate transmitted power is used.

scholarly journals Spatial–Temporal Distribution Variation of Ground-Level Ozone in China’s Pearl River Delta Metropolitan Region

2021 ◽  
Vol 18 (3) ◽  
pp. 872
Author(s):  
An Zhang ◽  
Jinhuang Lin ◽  
Wenhui Chen ◽  
Mingshui Lin ◽  
Chengcheng Lei
Keyword(s):  
Ozone Concentration ◽  
Pearl River Delta ◽  
Temporal Distribution ◽  
Ground Level ◽  
Metropolitan Region ◽  
Pearl River ◽  
Ozone Pollution ◽  
Ground Level Ozone ◽  
Ozone Concentrations ◽  
The North

Long-term exposure to ozone pollution will cause severe threats to residents’ physical and mental health. Ground-level ozone is the most severe air pollutant in China’s Pearl River Delta Metropolitan Region (PRD). It is of great significance to accurately reveal the spatial–temporal distribution characteristics of ozone pollution exposure patterns. We used the daily maximum 8-h ozone concentration data from PRD’s 55 air quality monitoring stations in 2015 as input data. We used six models of STK and ordinary kriging (OK) for the simulation of ozone concentration. Then we chose a better ozone pollution prediction model to reveal the ozone exposure characteristics of the PRD in 2015. The results show that the Bilonick model (BM) model had the highest simulation precision for ozone in the six models for spatial–temporal kriging (STK) interpolation, and the STK model’s simulation prediction results are significantly better than the OK model. The annual average ozone concentrations in the PRD during 2015 showed a high spatial variation in the north and east and low in the south and west. Ozone concentrations were relatively high in summer and autumn and low in winter and spring. The center of gravity of ozone concentrations tended to migrate to the north and west before moving to the south and then finally migrating to the east. The ozone’s spatial autocorrelation was significant and showed a significant positive correlation, mainly showing high-high clustering and low-low clustering. The type of clustering undergoes temporal migration and conversion over the four seasons, with spatial autocorrelation during winter the most significant.

scholarly journals Atmospheric Circulation Effects on Wind Speed Variability at Turbine Height

2007 ◽  
Vol 46 (4) ◽  
pp. 445-456 ◽  
Author(s):  
Katherine Klink
Keyword(s):  
Wind Speed ◽  
Pressure Gradient ◽  
Large Scale ◽  
Ground Level ◽  
The Arctic ◽  
Circulation Index ◽  
Regression Equations ◽  
Change Models ◽  
Wind Speeds ◽  
The North

Abstract Mean monthly wind speed at 70 m above ground level is investigated for 11 sites in Minnesota for the period 1995–2003. Wind speeds at these sites show significant spatial and temporal coherence, with prolonged periods of above- and below-normal values that can persist for as long as 12 months. Monthly variation in wind speed primarily is determined by the north–south pressure gradient, which captures between 22% and 47% of the variability (depending on the site). Regression on wind speed residuals (pressure gradient effects removed) shows that an additional 6%–15% of the variation can be related to the Arctic Oscillation (AO) and Niño-3.4 sea surface temperature (SST) anomalies. Wind speeds showed little correspondence with variation in the Pacific–North American (PNA) circulation index. The effect of the strong El Niño of 1997/98 on the wind speed time series was investigated by recomputing the regression equations with this period excluded. The north–south pressure gradient remains the primary determinant of mean monthly 70-m wind speeds, but with 1997/98 removed the influence of the AO increases at nearly all stations while the importance of the Niño-3.4 SSTs generally decreases. Relationships with the PNA remain small. These results suggest that long-term patterns of low-frequency wind speed (and thus wind power) variability can be estimated using large-scale circulation features as represented by large-scale climatic datasets and by climate-change models.

scholarly journals Assessment of Resource and Forecast Modeling of Wind Speed through An Evolutionary Programming Approach for the North of Tehuantepec Isthmus (Cuauhtemotzin, Mexico)

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3197 ◽  
Author(s):  
Luis López-Manrique ◽  
E. Macias-Melo ◽  
O. May Tzuc ◽  
A. Bassam ◽  
K. Aguilar-Castro ◽  
...  
Keyword(s):  
Wind Speed ◽  
Computation Time ◽  
Ground Level ◽  
Bimodal Distribution ◽  
Programming Approach ◽  
Climatic Data ◽  
Wind Speeds ◽  
Availability Analysis ◽  
The North ◽  
Wind Resource

This work studies the characteristics of the wind resource for a location in the north zone of Tehuantepec isthmus. The study was conducted using climatic data from Cuauhtemotzin, Mexico, measured at different altitudes above the ground level. The measured data allowed establishing the profile of wind speeds as well as the analysis of its availability. Analysis results conclude that the behavior of the wind speed presents a bimodal distribution with dominant northeast wind direction (wind flow of sea–land). In addition, the area was identified as feasible for the use of low speed power wind turbines. On the other hand, the application of a new approach for very short-term wind speed forecast (10 min) applying multi-gene genetic programming and global sensitivity analysis is also presented. Using a computational methodology, an exogenous time series with fast computation time and good accuracy was developed for the forecast of the wind speed. The results presented in this work complement the panorama for the evaluation of the resource in an area recognized worldwide for its vast potential for wind power.

scholarly journals Spatial Management Measures Alter Vessel Behavior in the Aleutian Archipelago

2021 ◽  
Vol 7 ◽  
Author(s):  
Benjamin K. Sullender ◽  
Kelly Kapsar ◽  
Aaron Poe ◽  
Martin Robards
Keyword(s):  
North Pacific ◽  
Risk Mitigation ◽  
Spatial Scales ◽  
Great Circle ◽  
Ecological Impacts ◽  
Study Region ◽  
The North ◽  
Management Measures ◽  
Before And After ◽  
The North Pacific

The Aleutian Archipelago and surrounding waters have enormous ecological, cultural, and commercial significance. As one of the shortest routes between North American and Asian ports, the North Pacific Great Circle Route, which crosses through the Aleutian Archipelago, is traveled by thousands of large cargo ships and tanker vessels every year. To reduce maritime risks and enhance navigational safety, the International Maritime Organization built upon earlier offshore routing efforts by designating five Areas To Be Avoided (ATBAs) in the Aleutian Islands in 2016. The ATBAs are designed to keep large vessels at least 50 nautical miles (93 km) from shore unless calling at a local port or transiting an authorized pass between islands. However, very few studies have examined the effectiveness of ATBAs as a mechanism for changing vessel behavior and thereby reducing the ecological impacts of maritime commerce. In this study, we use 4 years of satellite-based vessel tracking data to assess the effectiveness of the Aleutian ATBAs since their implementation in 2016. We determined whether vessels transiting the North Pacific Great Circle Route changed behavior after ATBA implementation, both in terms of overall route selection and in terms of compliance with each ATBA boundary. We found a total of 2,252 unique tankers and cargo vessels >400 gross tons transited the study region, completing a total of 8,794 voyages. To quantify routing changes of individual vessels, we analyzed the 767 vessels that transited the study region both before and after implementation. The percentage of voyages transiting through the boundaries of what would become ATBAs decreased from 76.3% in 2014–2015 (prior to ATBA designation) to 11.8% in 2016–2017 (after implementation). All five Aleutian ATBAs had significant increases in compliance, with the West ATBA showing the most dramatic increase, from 32.1% to 95.0%. We discuss the framework for ATBA enforcement and highlight the value of local institutional capacity for real-time monitoring. Overall, our results indicate that ATBAs represent a viable strategy for risk mitigation in sensitive ecological areas and that through monitoring, spatial protections influence vessel route decisions on multiple spatial scales.

scholarly journals Spatiotemporal variability of NO<sub>2</sub> and PM<sub>2.5</sub> over Eastern China: observational and model analyses with a novel statistical method

2018 ◽  
Vol 18 (17) ◽  
pp. 12933-12952 ◽  
Author(s):  
Mengyao Liu ◽  
Jintai Lin ◽  
Yuchen Wang ◽  
Yang Sun ◽  
Bo Zheng ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Eastern China ◽  
Ground Level ◽  
Vertical Gradient ◽  
Spatiotemporal Variability ◽  
Model Errors ◽  
Diurnal Variability ◽  
Near Surface ◽  
Synchronous Mode ◽  
The North

Abstract. Eastern China (27–41∘ N, 110–123∘ E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 µm (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF–EEMD analysis visualization package to evaluate the spatiotemporal variability of ground-level NO2, PM2.5, and their associations with meteorological processes over Eastern China in fall–winter 2013. Applying the package to observed hourly pollutant data reveals a primary spatial pattern representing Eastern China synchronous variation in time, which is dominated by diurnal variability with a much weaker day-to-day signal. A secondary spatial mode, representing north–south opposing changes in time with no constant period, is characterized by wind-related dilution or a buildup of pollutants from one day to another. We further evaluate simulations of nested GEOS-Chem v9-02 and WRF/CMAQ v5.0.1 in capturing the spatiotemporal variability of pollutants. GEOS-Chem underestimates NO2 by about 17 µg m−3 and PM2.5 by 35 µg m−3 on average over fall–winter 2013. It reproduces the diurnal variability for both pollutants. For the day-to-day variation, GEOS-Chem reproduces the observed north–south contrasting mode for both pollutants but not the Eastern China synchronous mode (especially for NO2). The model errors are due to a first model layer too thick (about 130 m) to capture the near-surface vertical gradient, deficiencies in the nighttime nitrogen chemistry in the first layer, and missing secondary organic aerosols and anthropogenic dust. CMAQ overestimates the diurnal cycle of pollutants due to too-weak boundary layer mixing, especially in the nighttime, and overestimates NO2 by about 30 µg m−3 and PM2.5 by 60 µg m−3. For the day-to-day variability, CMAQ reproduces the observed Eastern China synchronous mode but not the north–south opposing mode of NO2. Both models capture the day-to-day variability of PM2.5 better than that of NO2. These results shed light on model improvement. The EOF–EEMD package is freely available for noncommercial uses.

House I 10,8

2007 ◽  
Author(s):  
Penelope M. Allison
Keyword(s):  
Ground Level ◽  
The West ◽  
Comparable Group ◽  
North West ◽  
North East ◽  
The North ◽  
South Wall ◽  
Domestic Use ◽  
Small Shell ◽  
Lead Weights

The surviving plaster on the walls of this entranceway consisted of a high pink socle, delineated in red, with a white zone above. Ling observed that this overlay an earlier First-Style decoration on the east wall and that it had been patched in antiquity. Breaches are found in both the east and west walls. Outside the entrance, to either side, is a masonry bench (east bench: l.: 2.1 m, d.: 380 mm; west bench: l.: 2.4 m, d.: 460 mm), both much damaged. Finds within the entranceway consisted of bronze and iron studs, undoubtedly from the house door. Remains of plastered decoration survive on the south wall. Elia recorded a yellow dado, surmounted by a red band, with white plaster above. There is a breach in the north-west corner through to Unit no. 9, above a blocked doorway. At the centre of this front hall is a tufa impluvium (2.4 m × 2.1 m). In the north-west corner, 1 m above the pavement, were found: a small bronze ring; a bronze stud, similar to those in the entranceway and probably also from the front door; a fragment of a stone mortar or hand-mill; some glass beads; a small shell; and two bronze quadrantes, one of Nero dated ad 64. The fragmentary or loseable nature of these items suggests that they were disturbed from the ground level. Other small loseable items were found in the north-east corner: a small glass bottle, probably a toilet item; and possibly five more coins. One metre from the west side of the impluvium were found: another part of a hand-mill; two large stone weights; at least fifty-three lead weights, probably from a loom; and two other spherical stones, possibly also weights. The large number of lead weights is comparable with the quantity found under the stairway in room i of the Casa del Principe di Napoli. Another comparable group of forty loom weights was found together in a pit at Zugmantel. As Jongman noted, this amount would be equivalent to that required for one or perhaps two warp-weighted looms. It is therefore commensurate with the existence of such a loom, or looms, in this area, or of replacement loom weights, for domestic use.

Pure Curd Supply Chain

2016 ◽  
pp. 97-110
Author(s):  
Rajneesh Mahajan ◽  
Suresh Garg ◽  
P. B. Sharma
Keyword(s):  
Supply Chain ◽  
Food Safety ◽  
Safety Management ◽  
Manufacturing Sector ◽  
Hazard Analysis ◽  
Control Point ◽  
Ground Level ◽  
Critical Control Point ◽  
Shed Light

The modern food safety management comprises of ISO 22000:2005. It has modified the hazard analysis critical control point (HACCP) by embedding food safety management. It has created a standardized management system. The objective of current chapter is to endow a systematic approach for the ground level implementation of ISO 22000 in Indian pure curd supply chain management. The chapter is prepared utilizing combination of qualitative research and case study method. A case of Milsh Dairy Ltd. (MDL, organisation's name is disguised) was discussed to shed light on ISO 22000 features, comparative analysis between HACCP and ISO 22000. The research is limited to professional pure curd manufacturing sector. Authors have adopted the research methodology which can be applied to other sectors also.

Challenges in Channel Measurement and Modeling for RF Localization Inside the Human Body

2012 ◽  
Vol 3 (3) ◽  
pp. 18-37 ◽  
Author(s):  
Kaveh Pahlavan ◽  
Yunxing Ye ◽  
Ruijun Fu ◽  
Umair Khan
Keyword(s):  
Human Body ◽  
Path Loss ◽  
Signal Strength ◽  
Radio Propagation ◽  
Time Of Arrival ◽  
Precise Localization ◽  
Channel Measurement ◽  
Modeling Techniques ◽  
Endoscopy Capsule ◽  
Loss Models

In this invited paper, the authors introduce an overview of the fundamentals of radio frequency (RF) channel measurement and modeling techniques needed for localization inside the human body. To address these fundamentals, the authors use capsule endoscopy as an example application. The authors first provide the results of the Cramer Rao Lower Bound (CRLB) for received signal strength (RSS) based endoscopy capsule localization, inside the human body, using existing path-loss models for radio propagation. Then challenges demanding further research are highlighted for attaining more precise localization using the time-of-arrival (TOA) based ranging techniques.

2019 Ridgecrest Earthquake Reveals Areas of Los Angeles That Amplify Shaking of High-Rises

2020 ◽  
Vol 91 (6) ◽  
pp. 3370-3380
Author(s):  
Monica D. Kohler ◽  
Filippos Filippitzis ◽  
Thomas Heaton ◽  
Robert W. Clayton ◽  
Richard Guy ◽  
...  
Keyword(s):  
Los Angeles ◽  
Strong Motion ◽  
Ground Level ◽  
Site Amplification ◽  
Seismic Network ◽  
Los Angeles Basin ◽  
High Rise ◽  
The North ◽  
South Central ◽  
San Fernando

Abstract The populace of Los Angeles, California, was startled by shaking from the M 7.1 earthquake that struck the city of Ridgecrest located 200 km to the north on 6 July 2019. Although the earthquake did not cause damage in Los Angeles, the experience in high-rise buildings was frightening in contrast to the shaking felt in short buildings. Observations from 560 ground-level accelerometers reveal large variations in shaking in the Los Angeles basin that occurred for more than 2 min. The observations come from the spatially dense Community Seismic Network (CSN), combined with the sparser Southern California Seismic Network and California Strong Motion Instrumentation Program networks. Site amplification factors for periods of 1, 3, 6, and 8 s are computed as the ratio of each station’s response spectral values combined for the two horizontal directions, relative to the average of three bedrock sites. Spatially coherent behavior in site amplification emerges for periods ≥3  s, and the maximum calculated site amplifications are the largest, by factors of 7, 10, and 8, respectively, for 3, 6, and 8 s periods. The dense CSN observations show that the long-period amplification is clearly, but only partially, correlated with the depth to basement. Sites with the largest amplifications for the long periods (≥3  s) are not close to the deepest portion of the basin. At 6 and 8 s periods, the maximum amplifications occur in the western part of the Los Angeles basin and in the south-central San Fernando Valley sedimentary basin. The observations suggest that the excitation of a hypothetical high-rise located in an area characterized by the largest site amplifications could be four times larger than in a downtown Los Angeles location.

scholarly journals Long-time resistivity monitoring of a freshwater/saltwater transition zone using the vertical electrode system SAMOS

2018 ◽  
Vol 54 ◽  
pp. 00009 ◽  
Author(s):  
Michael Grinat ◽  
Dieter Epping ◽  
Robert Meyer
Keyword(s):  
Transition Zone ◽  
Ground Level ◽  
Temporal Changes ◽  
Electrode System ◽  
The North ◽  
Vertical Electrode ◽  
Catchment Areas ◽  
Long Time ◽  
Pumping Rates ◽  
Electrode Systems

In September 2009 two newly developed vertical electrode systems were installed in boreholes in the water catchment areas Waterdelle and Ostland at the North Sea island Borkum to monitor possible changes of the transition zone between the freshwater lens and the underlying saltwater. The vertical electrode systems, which were both installed between 44 m and 65 m below ground level, are used for geoelectrical multi-electrode measurements carried out automatically several times per day; the measurements are still ongoing. The whole system consisting of a vertical electrode system in a borehole and the measuring unit at ground level is called SAMOS (Saltwater Monitoring System). At both locations the data show a clear resistivity decrease that indicates the transition zone between freshwater and saltwater. The depth of the transition zone as well as the kind of resistivity decrease is very stable since 2010. Temporal changes are visible if single depths are considered. In 2015 Miriam Ibenthal used a vertical 2D density-dependent groundwater flow model to explain the long-term resistivity measurements and showed that the temporal changes at CLIWAT 2 (Ostland) could be explained by variations of the groundwater level, changing groundwater recharge rates and changing pumping rates of the nearby located drinking water supply wells.

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