scholarly journals Swath-altimetry measurements of the main stem Amazon River: measurement errors and hydraulic implications

2015 ◽  
Vol 19 (4) ◽  
pp. 1943-1959 ◽  
Author(s):  
M. D. Wilson ◽  
M. Durand ◽  
H. C. Jung ◽  
D. Alsdorf
Keyword(s):  
Surface Water ◽  
Water Surface ◽  
Hydraulic Model ◽  
Two Dimensions ◽  
Main Stem ◽  
Two Dimensional ◽  
Cross Sectional ◽  
Temporal Sampling ◽  
Spatio Temporal ◽  
The Impact

Abstract. The Surface Water and Ocean Topography (SWOT) mission, scheduled for launch in 2020, will provide a step-change improvement in the measurement of terrestrial surface-water storage and dynamics. In particular, it will provide the first, routine two-dimensional measurements of water-surface elevations. In this paper, we aimed to (i) characterise and illustrate in two dimensions the errors which may be found in SWOT swath measurements of terrestrial surface water, (ii) simulate the spatio-temporal sampling scheme of SWOT for the Amazon, and (iii) assess the impact of each of these on estimates of water-surface slope and river discharge which may be obtained from SWOT imagery. We based our analysis on a virtual mission for a ~260 km reach of the central Amazon (Solimões) River, using a hydraulic model to provide water-surface elevations according to SWOT spatio-temporal sampling to which errors were added based on a two-dimensional height error spectrum derived from the SWOT design requirements. We thereby obtained water-surface elevation measurements for the Amazon main stem as may be observed by SWOT. Using these measurements, we derived estimates of river slope and discharge and compared them to those obtained directly from the hydraulic model. We found that cross-channel and along-reach averaging of SWOT measurements using reach lengths greater than 4 km for the Solimões and 7.5 km for Purus reduced the effect of systematic height errors, enabling discharge to be reproduced accurately from the water height, assuming known bathymetry and friction. Using cross-sectional averaging and 20 km reach lengths, results show Nash–Sutcliffe model efficiency values of 0.99 for the Solimões and 0.88 for the Purus, with 2.6 and 19.1 % average overall error in discharge, respectively. We extend the results to other rivers worldwide and infer that SWOT-derived discharge estimates may be more accurate for rivers with larger channel widths (permitting a greater level of cross-sectional averaging and the use of shorter reach lengths) and higher water-surface slopes (reducing the proportional impact of slope errors on discharge calculation).

scholarly journals Swath altimetry measurements of the mainstem Amazon River: measurement errors and hydraulic implications

2014 ◽  
Vol 11 (8) ◽  
pp. 9399-9434
Author(s):  
M. D. Wilson ◽  
M. Durand ◽  
H. C. Jung ◽  
D. Alsdorf
Keyword(s):  
Surface Water ◽  
Measurement Errors ◽  
Water Surface ◽  
Hydraulic Model ◽  
Two Dimensions ◽  
Temporal Sampling ◽  
Dimensional Measurements ◽  
Spatio Temporal ◽  
Ocean Topography ◽  
The Impact

Abstract. The Surface Water and Ocean Topography (SWOT) mission, scheduled for launch in 2020, will provide a step-change improvement in the measurement of terrestrial surface water storage and dynamics. In particular, it will provide the first, routine two-dimensional measurements of water surface elevations. In this paper, we aimed to (i) characterize and illustrate in two-dimensions the errors which may be found in SWOT swath measurements of terrestrial surface water, (ii) simulate the spatio-temporal sampling scheme of SWOT for the Amazon, and (iii) assess the impact of each of these on estimates of water surface slope and river discharge which may be obtained from SWOT imagery. We based our analysis on a "virtual mission" for a 300 km reach of the central Amazon (Solimões) River at its confluence with the Purus River, using a hydraulic model to provide water surface elevations according to SWOT spatio-temporal sampling to which errors were added based on a two-dimension height error spectrum derived from the SWOT design requirements. We thereby obtained water surface elevation measurements for the Amazon mainstem as may be observed by SWOT. Using these measurements, we derived estimates of river slope and discharge and compared them to those obtained directly from the hydraulic model. We found that cross-channel and along-reach averaging of SWOT measurements using reach lengths of greater than 4 km for the Solimões and 7.5 km for Purus reduced the effect of systematic height errors, enabling discharge to be reproduced accurately from the water height, assuming known bathymetry and friction. Using cross-section averaging and 20 km reach lengths, results show Nash–Sutcliffe model efficiency values of 0.99 for the Solimões and 0.88 for the Purus, with 2.6 and 19.1% average overall error in discharge, respectively.

scholarly journals Two Dimensional Model for Backwater Geomorphology: Darby Creek, PA

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2204 ◽  
Author(s):  
Hosseiny ◽  
Smith
Keyword(s):  
Urban Areas ◽  
Water Surface ◽  
Integrated Model ◽  
Shear Stresses ◽  
Two Dimensional ◽  
Morphological Alterations ◽  
Digital Elevation ◽  
Starting Point ◽  
Spatio Temporal ◽  
Elevation Model

Predicting morphological alterations in backwater zones has substantial merit as it potentially influences the life of millions of people by the change in flood dynamics and land topography. While there is no two-dimensional river model available for predicting morphological alterations in backwater zones, there is an absolute need for such models. This study presents an integrated iterative two-dimensional fluvial morphological model to quantify spatio-temporal fluvial morphological alterations in normal flow to backwater conditions. The integrated model works through the following steps iteratively to derive geomorphic change: (1) iRIC model is used to generate a 2D normal water surface; (2) a 1D water surface is developed for the backwater; (3) the normal and backwater surfaces are integrated; (4) an analytical 2D model is established to estimate shear stresses and morphological alterations in the normal, transitional, and backwater zones. The integrated model generates a new digital elevation model based on the estimated erosion and deposition. The resultant topography then serves as the starting point for the next iteration of flow, ultimately modeling geomorphic changes through time. This model was tested on Darby Creek in Metro-Philadelphia, one of the most flood-prone urban areas in the US and the largest freshwater marsh in Pennsylvania.

Organisational empowerment and assertive communication behaviours: a survey of Jordanian newly qualified nurses

2020 ◽  
Vol 29 (7) ◽  
pp. 419-425 ◽  
Author(s):  
Muhammad W Darawad ◽  
Mansour Mansour ◽  
Tahany Al-Niarat
Keyword(s):  
Two Dimensions ◽  
Early Years ◽  
Cross Sectional Survey ◽  
Speaking Up ◽  
Structural Empowerment ◽  
Cross Sectional ◽  
Clinical Scenarios ◽  
Communication Behaviours ◽  
Speak Up ◽  
The Impact

Background: Newly qualified nurses (NQNs) face several challenges in their early years of practice. Being empowered and able to speak up against unsafe practice are two important pillars for practising nursing safely and competently. Little research has examined the potential correlation between those two dimensions in the context of NQNs in Jordan. Aims: To investigate the correlation between NQNs' perceived structural empowerment in their work setting and their willingness to challenge unsafe practice in some hypothetical clinical scenarios. Methods: A cross-sectional survey involved 233 NQNs, who completed a self-administered questionnaire between January and March 2016. Findings: Participants reported moderate levels of both perceived structural empowerment and willingness to speak up against unsafe practice. There was a statistically significant positive correlation between the total structural empowerment score and the mean score for speaking up against unsafe practice. Conclusion: The findings highlight the impact of peer, managerial and overall organisational support on enabling NQNs to become more empowered and assertive. Concrete, collaborative and organisation-wide efforts must be considered to foster greater empowerment of NQNs, but also revisiting work priorities to include supporting and advocating assertive communication skills among the more vulnerable of the newly qualified cohort.

scholarly journals Continuous Monitoring of the Spatio-Temporal Patterns of Surface Water in Response to Land Use and Land Cover Types in a Mediterranean Lagoon Complex

2019 ◽  
Vol 11 (12) ◽  
pp. 1425 ◽  
Author(s):  
Zhichao Li ◽  
Yujie Feng ◽  
Nadine Dessay ◽  
Eric Delaitre ◽  
Helen Gurgel ◽  
...  
Keyword(s):  
Surface Water ◽  
Human Activities ◽  
Coastal Wetlands ◽  
Annual Variation ◽  
Coastal Lagoons ◽  
Sand Beach ◽  
Mediterranean Lagoon ◽  
Potential Link ◽  
Spatio Temporal ◽  
The Impact

Mediterranean coastal lagoons and their peripheral areas often provide a collection of habitats for many species, and they often face significant threats from anthropogenic activities. Diverse human activities in such areas directly affect the spatio-temporal dynamic of surface water and its ecological characteristics. Monitoring the surface water dynamic, and understanding the impact of human activities are of great significance for coastal lagoon conservation. The Regional Natural Park of Narbonne includes a typical Mediterranean lagoon complex where surface water dynamic and its potential link with local diverse human activities has not yet been studied. In this context, based on all the available Landsat images covering the study area during 2002–2016, this study identified the water and non-water classes for each satellite observation by comparing three widely used spectral indices (i.e., NDVI, NDWI and MNDWI) and using the Otsu method. The yearly water frequency index was then computed to present the spatio-temporal dynamic of surface water for each year, and three water dynamic scenarios were also identified for each year: permanent water (PW), non-permanent water (NPW) and non-water (NW). The spatial and inter-annual variation in the patterns of the three water scenarios were characterized by computing the landscape metrics at scenario-level quantifying area/edge, shape, aggregation and fragmentation. Finally, the quantitative link between different land use and land cover (LULC) types derived from the LULC maps of 2003, 2012 and 2015 and the surface water dynamic scenarios was established in each of the 300 m × 300 m grid cells covering the study area to determine the potential impact of human activities on the surface water dynamic. In terms of the inter-annual variation during 2002–2016, PW presented an overall stability, and NPW occupied only a small part of the water surface in each year and presented an inter-annual fluctuation. NPW had a smaller patch size, with lower connectivity degree and higher fragmentation degree. In terms of spatial variation during 2002–2016, NPW often occurred around PW, and its configurational features varied from place to place. Moreover, PW mostly corresponded to the natural lagoon, and salt marsh (as a part of lagoons), and NPW had a strong link with arable land (agricultural irrigation) and salt marsh (salt production), sand beach/dune, coastal wetlands and lagoon for the LULC maps of 2003, 2012 and 2015. However, more in-depth analysis is required for understanding the impact of sand beach/dune, coastal wetlands and lagoon on surface water dynamics. This study covers the long-term variations of surface water patterns in a Mediterranean lagoon complex having intense and diverse human activities, and the potential link between LULC types and the water dynamic scenarios was investigated on different dates. The results of the study should be useful for environmental management and protection of coastal lagoons.

scholarly journals Compensation Management and Employee Wellbeing of Academic Staff in Ugandan Private Universities during COVID-19 Lockdown

2021 ◽  
Vol 3 (1) ◽  
pp. 1-12
Author(s):  
Mugizi Wilson ◽  
Joseph Rwothumio ◽  
Christopher Mwujuka Amwine
Keyword(s):  
Multiple Regression ◽  
Academic Staff ◽  
Private Universities ◽  
Well Being ◽  
Two Dimensions ◽  
Subjective Well Being ◽  
Cross Sectional ◽  
Compensation Management ◽  
Cross Sectional Design ◽  
The Impact

This study examined the impact of compensation management on academic staff's employee well-being in private universities in Uganda during the COVID-19 lockdown. Two dimensions of compensation management considered were compensation determination and compensation administration. Employee well-being was studied in terms of psychological well-being, social well-being, workplace well-being and subjective well-being. This study used a cross-sectional design on a sample of academic staff from five private universities.  Factor analysis was used to identify key items of compensation management and employee well-being, followed by descriptive, correlation and multiple regression analyses. Multiple regression analysis assessed the magnitude and strength of the impact of compensation management on employee well-being. The results supported the hypotheses on the influence of compensation determination and administration on employee well-being. Therefore, compensation determination and administration are important in enhancing the academic staff's well-being in private universities in contingent situations such as COVID-19 lockdown. In managing compensation issues in contingent situations, managers of private universities should determine and administer compensation considering employees' interests. This study adds to the scanty literature on compensation management and employee well-being. It identifies compensation management factors that organisations should consider to promote employee well-being in contingent situations.

Hydroelastic Modeling of Wet Deck Slamming on Multihull Vessels

2021 ◽  
Vol 39 (03) ◽  
pp. 225-239
Author(s):  
Jan Kvalsvold ◽  
Odd M. Faltinsen
Keyword(s):  
Water Surface ◽  
Normal Modes ◽  
Two Dimensional ◽  
Sea Waves ◽  
Rotatory Inertia ◽  
Shear Deformations ◽  
Inertia Effects ◽  
Elastic Stresses ◽  
The Impact ◽  
Impact Region

Slamming against the wet deck of a multihull vessel in head sea waves is studied analytically and numerically. The theoretical slamming model is a two-dimensional, asymptotic method valid for small local angles between the undisturbed water surface and the wet deck in the impact region. The disturbance of the water surface as well as the local hydroelastic effects in the slamming area are accounted for. The elastic deflections of the wet deck are expressed in terms of "dry" normal modes. The structural formu­lation accounts for the shear deformations and the rotatory inertia effects in the wet deck. The findings show that the slamming loads on the wet deck and the resulting elastic stresses in the wet deck are strongly influenced by the elasticity of the wet deck structure.

Observation of the Full Interface of Multi-level Interconnects for Sub-Half-Micron Devices

1996 ◽  
Vol 446 ◽  
Author(s):  
Y. Hirose ◽  
T. Katayama ◽  
N. Fujiki ◽  
T. Ohno ◽  
M. Sekine ◽  
...  
Keyword(s):  
Cross Section ◽  
Electrical Resistance ◽  
Interface Layer ◽  
Two Dimensions ◽  
Two Dimensional ◽  
Cross Sectional ◽  
Present Technique ◽  
Multi Level ◽  
Observation Method ◽  
Sectional Analysis

1. AbstractIn recent years, the problem of electrical resistance of vias and contact holes has become greater because a thin insulated layer formed at the interface of the hole has become a serious difficulty in the manufacture of ULSIs. In using conventional techniques of cross sectional analysis to examine the cause, only one cross section of the hole can be analyzed, therefore there is the problem that the two-dimensional interface layer formed cannot be analyzed exactly.In this paper, we have developed a new observation method to inspect two dimensions of the layer formed locally at the interface of the holes. This new observation method gives the configuration, coverage, and element map of the interface layer because the full interface of holes can be inspected; therefore, the process margin can be discussed. The present technique is demonstrated in failure analysis of sub-half-micron vias filled with tungsten.

Shopping value and patronage: when satisfaction and crowding count

2019 ◽  
Vol 38 (2) ◽  
pp. 137-150
Author(s):  
Tapas Ranjan Moharana ◽  
Debasis Pradhan
Keyword(s):  
Structural Equation ◽  
Group Analysis ◽  
Theoretical Models ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Cross Sectional ◽  
Content Type ◽  
Patronage Intention ◽  
Hedonic Utilitarian ◽  
The Impact

Purpose The purpose of this paper is to compare two competing models denoting two dimensions (hedonic and utilitarian) and three dimensions (hedonic, utilitarian and social) of the construct “value” and investigates their relative influence on satisfaction, future patronage intention (FPI) and word-of-mouth (WoM) in a hypermarket context. Additionally, the study examines if these relationships are contingent upon gender and shoppers’ perception of retail crowding. Design/methodology/approach The proposed models and the hypotheses were tested using structural equation modelling, across two cross-sectional studies (n1=268, n2=259). The multi-group analysis was used to test moderated relationships. Findings The study demonstrates that satisfaction mediates the impact of shopping value on FPI and WoM. The model that includes utilitarian, hedonic and social value explains higher variance in satisfaction and WoM than that is evidenced in the alternate model comprising utilitarian and hedonic values. Shoppers’ gender and perceived retail crowding moderate the influence of shopping value on satisfaction. Practical implications Retail managers should understand that enjoyable and social shopping experience of the consumers lead to satisfaction, which in turn plays a pivotal role in the formation of FPI and WoM. Managers discern that a moderate level of crowding is better than the extremely low or high level of density. Originality/value Amidst a lack of unanimity on the dimensionality of shopping value, this is one of the first studies to evaluate the two theoretical models of shopping value having two dimensions and three dimensions, respectively. An understanding of gender and retail crowding perceptions is crucial in shopping value judgments.

scholarly journals Examining the Impact of Two Dimensions of Precarious Employment, Vulnerability and Insecurity on the Self-Reported Health of Men, Women and Migrants in Australia

2020 ◽  
Vol 17 (20) ◽  
pp. 7540
Author(s):  
Alison Daly ◽  
Marc B. Schenker ◽  
Elena Ronda-Perez ◽  
Alison Reid
Keyword(s):  
Migrant Workers ◽  
The Philippines ◽  
Two Dimensions ◽  
P Value ◽  
Cross Sectional ◽  
Precarious Employment ◽  
Employment Conditions ◽  
Negative Effect ◽  
Reported Health ◽  
The Impact

Precarious employment is increasing and adversely affects health. We aimed to investigate how perception of precariousness in current employment impacts gender and migrant workers in Australia. Using cross-sectional interviews of 1292 workers born in Australia, New Zealand, India and the Philippines, data were collected on self-reported health, employment conditions and sociodemographics. Factor analysis of nine questions about perceptions of current employment revealed two dimensions, vulnerability and insecurity. Women had higher vulnerability scores (µ = 6.5 vs. µ = 5.5, t = 5.40, p-value (p) < 0.000) but lower insecurity scores (µ = 8.6 vs. µ = 9.3 t = −4.160 p < 0.0003) than men. Filipino-born workers had higher vulnerability compared with other migrant workers (µ = 6.5 vs. µ = 5.8 t = −3.47 p < 0.0003), and workers born in India had higher insecurity compared with other migrant workers (µ = 9.8 vs. µ = 8.9, t = −6.1 p < 0.0001). While the prevalence of insecurity varied by migrant status, the negative effect on health was higher for Australian-born workers than migrants. Increasing levels of vulnerability and insecurity impacted self-reported health negatively (Coefficient (Coef).0.34 p < 0.0001; Coef.0.25 p < 0.0001, respectively). The combination of high vulnerability and high insecurity had the greatest impact on health (Coef. 2.37 p = 0.002), followed by high vulnerability and moderate insecurity (Coef. 2.0 p = 0.007). Our study suggests that understanding both changes in employment conditions over time as well as knowledge of cultural patterns may offer the best chance of understanding the impact of precarious employment experiences.

scholarly journals Dominant role of two-photon vertex in nonlinear response in two-dimensional Dirac systems

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Habib Rostami ◽  
Emmanuele Cappelluti
Keyword(s):  
Nonlinear Response ◽  
Dominant Role ◽  
Two Dimensions ◽  
Two Dimensional ◽  
Nonlinear Transport ◽  
Many Body Theory ◽  
Clean Limit ◽  
Two Photon ◽  
Dirac Systems ◽  
The Impact

AbstractWe show that the standard concepts of nonlinear response to electromagnetic fields break down in two-dimensional Dirac systems, like graphene, in the quantum regime close to the Dirac point. We present a compelling many-body theory for nonlinear transport focusing on disorder scattering as a benchmark example. We show that, although the diamagnetic two-photon vertex is absent at the non-interacting level, disorder effects give rise to a self-generation of such two-photon vertex surviving even in the clean limit. We predict that the two-photon vertex self-generation is present only in two dimensions. The impact of such a striking scenario on the nonlinear quantum transport is discussed, predicting a huge enhancement of third-order dc conductivity comparing to the common models.

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