We examined the seasonal and solar flux dependence of the occurrence of freshly generated intermediate scale (100 m to few km) equatorial spread F (ESF) irregularities during magnetically quiet (Q) ...and disturbed (D) periods. We utilized long‐term (1992–2006 and 2013–2015) amplitude scintillation data on a 251 MHz signal recorded at Tirunelveli (dip lat. 1.5°N ). Also, ionosonde data (1990–2003) recorded at Trivandrum (dip lat. 0.5°N) are used. The presence of fresh ESF (F‐ESF) is identified using the maximum cross‐correlation between intensity variations recorded by two spaced receivers on a magnetic east‐west baseline. We find distinct differences in the seasonal and solar flux dependence of the usual postsunset (<22 LT) generation of F‐ESF on both Q‐ and D‐days. Interesting feature is that F‐ESF linked moderate–strong scintillations are more prevalent on D‐days as compared to Q‐days in both early (18–22 LT) and later (>22 LT) phase of evolution of the irregularities. It directly hints toward the difference in the spatial structuring (spatial scales) of F‐ESF on D‐days as compared to Q‐days. On D‐days, the occurrence of F‐ESF is more likely around midnight and early‐morning hours in all seasons. Whereas on Q‐days, the postmidnight F‐ESF is found to occur mainly during solstices of low solar activity. The possible sources for the generation of F‐ESF around midnight on Q‐days of solstices during low solar activity are examined. We also find that perturbation electric field linked with F‐ESF on D‐days sustains for longer time, which results in longer durations of the active phase of equatorial plasma bubbles.
Key Points
Perturbation electric field linked with fresh ESF is sustained for longer duration on disturbed days
Disturbed time fresh ESF irregularities produce stronger scintillations as compared to quiet time fresh ESF
Theoretical model indicates a smaller altitudinal extent for postmidnight fresh ESF on quiet days as compared to disturbed days
A series of numerical simulations were completed to investigate the behavior of intact, fire-damaged, and Carbon Fiber-Reinforced Polymers (CFRP) retrofitted reinforced concrete (RC) bridge columns ...of varying sizes subjected to vehicle collisions. Three-dimensional finite element models of isolated RC columns and their foundation systems surrounded by soil volumes were developed using LS-DYNA. A comprehensive parametric study was carried out to investigate the effects of nine demand and design parameters on the performance of bridge columns. Studied parameters included: column diameter, column height, unconfined compressive strength, steel reinforcement ratio, fire duration, CFRP wrap thickness, wrapping configuration, vehicle’s mass, and vehicle’s speed. For each studied scenario, Peak Twenty-five Milli-second Moving Average (PTMSA) was employed to estimate the Equivalent Static Force (ESF) corresponding to each vehicle collision scenario. Resulting ESFs were then utilized to assess effectiveness of the current ESF approach available in the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO-LRFD) Bridge Design Specification for analyzing and helping design bridge columns under vehicle collision. Multivariate nonlinear regression analyses were used to derive an empirically based, simplified equation to predict the ESF that corresponds to a vehicle collision. Rather than constant design force, this equation established a correlation between ESF and kinetic energy, column axial capacity, and column height. Results indicated that the proposed equation is reliable and can accurately predict ESFs over a diverse range of collision scenarios that included intact, fire damaged, and CFRP retrofitted columns. To facilitate realistic implementation of the derived equation, an ESF assessment framework was also devised.
•Performance assessment and insights on intact, fire-damaged, and CFRP retrofitted bridge pier columns under vehicle impact.•Developed 3D finite element models of isolated bridge column, foundation system, and surrounding soil domain using LS-DYNA.•Conducted a comprehensive parametric study including nine demand and design variables.•Derived an empirically based, simplified equation that predicts ESF over a wide range of vehicle collision scenarios.•Proposed an assessment framework to facilitate the implementation of the proposed equation.
Using the ground-based multi instruments observations in Hainan and Southeast Asia, as well as space-based observations, the long lasting events of ionospheric irregularities occurred in the ...equatorial region of East Asia on the night of March 31, 2014 are studied. Concurrent observations at Hainan station indicate that ionospheric irregularities measured with different instruments showed distinct spatial structures and temporal variation, mainly from sunset to midnight (19-23LT) and even to post midnight. The 3-m-scale irregularities detected by VHF radar first attenuated and disappeared at 01LT, then the 400-meter-scale irregularities (GPS scintillations) vanished at 03LT, and finally the larger-scale irregularities (spread F) ended at 05LT. It provides a directly observational evidence that the larger the scale is, the latter the irregularities decay after midnight. Ionospheric irregularities near the magnetic equator (ME) and the equatorial abnormal peaks (EAPs) mainly occurred from after sunset to midnight (19-01LT), but there were distinct morphological differences after midnight. The irregularities near ME were attenuated and disappeared rapidly, while irregularities near EAPs weakened obviously, but lasted until dawn. The plasma depletions observed by the SWARM satellite in the latter half of the night were clearly related to the TEC fluctuations at JOG2 site, the ionospheric scintillations and spread F at Hainan station. The quasiperiodic structures of plasma bubbles observed by C/NOFS satellite were clearly related to the occurrence of ionospheric irregularities in Hainan and Southeast Asia, which indicated that the seeding of atmospheric gravity waves may play an important role in the generation of ESF/EPB irregularities, even in the latter half of the night.
•Equinoctial asymmetry in Satellite traces (ST), low latitude Esb layers and PRE.•Wave amplification is seen during ESF days than other days around PRE times.•Phase propagation suggests upward ...propagating GWs during ESF days than non-ESF days.
We investigate the ionogram signatures of LSWS (satellite traces) and low latitude Esb layers as a basis for causing variabilities of ESF irregularities in addition to post sunset vertical drift using ground based ionosondes located at Tirunelveli (8.71°N, 77.75°E, Geomag. Lat 0.21°N) and Hyderabad (17.38°N, 78.48°E, Geomag. Lat 8.74°N) for the year 2015. Results show, statistically, that the presence/absence of STs are higher/lower than the absence/presence of Esb prior to occurrence/non-occurrence of ESF during all the seasons. This implies the importance of ST/LSWS in the ESF occurrence. Results of weak correlation of low latitude Esb layers with ESF possibly indicate its coupling to higher apex altitude than base of the F-layer. Significant equinoctial asymmetry is also observed in both the ESF and ST occurrences wherein vernal is dominant than autumn equinox. Band-pass filtered h’F oscillations of 1–1.5 h reveal significant wave amplification during the PRE on ESF than non-ESF days and also during vernal than autumn equinox. Further investigations suggest that the height oscillations of early ESF and delayed ESF are amplified according to their onset time of ESF. The study suggests that post-sunset height rise of F-layer together with the presence of LSWS provide suitable conditions for the ESF development. Further, the presence of downward phase propagation on ESF days than other days indicate the presence of upward propagating Gravity Waves in the initiation of these wave structures.
Analyzing urban scaling relations can help predict the future development of cities and derive scale adjusted metropolitan indicators (SAMIs) to characterize the city's performance. However, existing ...studies treat cities as individual systems but ignore the spatial autocorrelation between them. Here, we propose a framework that incorporates the influence of spatial autocorrelation into urban scaling analysis. We use an eigenvector spatial filtering (ESF) model to capture the spatial effect when modeling the scaling relations of cities. Based on the residuals of the ESF model, we propose a new set of urban indicators—spatial and scale adjusted metropolitan indicators (SSAMIs)—to address the effect of spatial autocorrelation on SAMIs. The results of our experiments in China and the United States show that compared with non-spatial models, the ESF model could generate better-fitted results when estimating the scaling relations. The results also reveal that using SSAMIs could avoid overestimations of cities in developed regions and underestimations of cities in less developed regions. This study proposes a novel attempt to deal with the spatial autocorrelation effect in urban scaling analysis. It provides insights for understanding the urban scaling law and enhanced indicators for the evaluation of cities.
•The presence of spatial autocorrelation between cities could lead to misspecification of the urban scaling law.•A framework is proposed to capture the spatial effect in urban scaling analysis.•SSAMIs are proposed to give spatial and scale independent evaluations of cities.
The objective of sustaining smart, sustainable and cohesive inclusive growth, framed by the European strategy, is in line with the global commitments of the Sustainable Development Goals. Thus, an ...analysis of people’s attitudes towards social policy and perceptions of professional development in Poland against European development policy is crucial. The nationwide representative sample included 1000 respondents aged 18–64. The study used principal component analysis (PCA), an approach for the multi-response optimisation. The results indicate that respondents’ evaluations are in line with the direction of EU labour policy, where their decisions correspond to the planned priorities oriented towards inclusion and cohesion. The PCA analysis showed that employee competencies and priorities for individual standing can be considered strongly correlated. Competencies were also found to be important for the platform to support systemic development. However, the items included in the analysis that are beyond the scope of the ESF+ , although even correlated, are of lesser importance. The research results allow to expand knowledge on the perception of the development policy facets promoted by the EU, supplemented by themes of leadership or immigrants. The study may become a starting point for inclusive and cohesive working climate research.
•Assessment of perceptions regarding professional development in EU development policy.•Key components: leadership styles, entry training criteria, competencies, beneficiaries, and priorities.•Respondents exhibit greater support for policy objectives than previously assumed.•Utilization of PCA to enhance efficiency in evaluating multi-response data.•PCA to transform complex information into clear and actionable insights.
Spain is at the bottom in the absorption of European funds, and there is a need to research why. This paper starts from the idea that the problem could, among other issues, be related to the ...ineffectiveness of administrative communication, both in terms of transparency and dissemination. These dimensions are key for the innovation and open government principles endorsed by the better regulation initiative of the EU and have hardly been studied in this respect by academics. For the period 2021–2027, Spain will receive more than 34,692 million euros from the ERDF and ESF+ funds. The autonomous communities and cities must report on this aid based on communication plans and strategies for the operational programs. After compiling them, assessing their ease of access and analyzing some of their characteristics, such as the levels of execution of their budgets, this research analyzes how the 19 official websites inform about the ERDF and ESF. In several cases, the results point to inefficient institutional management of budgets for communication, as well as obstacles to accessing online content, which is key to transparency. The extent to which these shortcomings may be related to the lack of demand for European funding could be analyzed in future studies.
Lunar observations have been used for sensor performance assessments for a number of Earth-observing instruments, including the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and ...Aqua, and the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP (SNPP) and NOAA-20 (N20). While the primary purpose of lunar observations in MODIS and VIIRS is radiometric calibration, these observations have been leveraged for other sensor performance assessments, such as spatial registration and deriving the modulation transfer function (MTF). In this work, we will derive the lunar MTF using a knife-edge approach similar to the previous work. However, to further isolate the edge of the lunar disk when deriving the edge spread function (ESF), we will apply a lunar surface variation correction using a model based on data obtained by the spectral profiler (SP) onboard the SELENE spacecraft. This model was provided to us by the National Institute of Advanced Industrial Science and Technology (AIST) in Japan. To align the measured and modeled data, we developed techniques for projecting the measured lunar surface pixels onto the radiance maps produced by the SP model. We correct the lunar surface variation while preserving the signal of the lunar disk edge in the ESF and then calculate the MTF results using standard techniques. These results are in good agreement with previously published results from both Moon-based observations in MODIS and VIIRS and from the spectroradiometric calibration assembly (SRCA) on MODIS. With the exception of MODIS bands 1 and 2, the MTF is stable on orbit for the reflective bands in both instruments.
Incoherent scatter radars near magnetic equator regularly measured a vertical shear in zonal drifts of the evening background plasma, with westward drifts below the equatorial F region peak and ...eastward drifts above. We report here observations of a clear shear structure in the zonal drifts of 3 m irregularities inside spread F (SF) backscatter plumes measured with a 47.5 MHz coherent scatter radar operated at a low‐latitude site Sanya (18.4°N, 109.6°E; dip latitude 12.8°N). The radar interferometry analysis on the zonal drifts of the 3 m irregularities yields results consistent with that estimated from the irregularity echo Doppler velocity measurements with multiple beams. It is shown that the SF 3 m irregularities move westward at the lowest altitudes, while at higher altitudes in the same SF plume structure, the 3 m irregularities drift eastward. One interesting point is that the vertical shear of zonal drifts was centered at ~300 km altitude over Sanya, which maps to an apex altitude of ~650 km at magnetic equator and is thus apparently higher than the apex altitudes 250–450 km where the zonal velocity shear has usually been observed. Analysis of the observations suggests that while the possibility of local generation of the shear flow of the irregularities can exist, the possibility of a plasma vortex appearing at relative high altitudes causing the zonal drift shear of F region 3 m irregularities measured over Sanya cannot be totally ruled out.
Key Points
A vertical shear in zonal drifts of ESF 3 m irregularities is detected at low latitude
The shear centers at an apex altitude of 650 km over dip equator
Better knowledge of plasma zonal drift shear at low latitude are needed
Climate change is a result of the environmental degradation due to human activities and has the potential to become a climate disaster that threatens human life and causes social problems. Through ...the ESF, World Bank expect that infrastructure development can go hand in hand with environmental and social safeguards. To obtain information about the level of satisfaction of the performance of this ESF indicator, this study was conducted using the Importance Performance Analysis method to compare the expectations and the realities of the performance of the critical ESF indicators in Indonesia. The study involved 80 respondents of infrastructure project actors in Indonesia and found that 40% of the ESF indicators had performed well and met their expectations. Meanwhile, three indicators were inefficient or the performance exceeded the expectations, namely ESS6.3, ESS2.3 and ESS6.1. ESS7.2 and ESS8.1. This study is expected to contribute to developing a standardized and integrated ESF in Indonesia. Furthermore, the results of this study can be used as a consideration in further research, especially the use of the ESF variables as a moderator in modeling project social conflict.
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