scholarly journals Quantifying multifrequency acoustic characterization accuracy for ice model development applications

2020 ◽  
Author(s):  
David R. Topham ◽  
John R. Marko
Keyword(s):  
Cross Sections ◽  
Field Data ◽  
Growth Models ◽  
Model Development ◽  
Particle Number Density ◽  
Frazil Ice ◽  
Ice Volume ◽  
Acoustic Characterization ◽  
Key Factor ◽  
Transducer Calibration

Abstract. Multi-frequency acoustic profiling is critically examined to estimate accuracies currently attainable in characterizing frazil suspensions: with primary interests focused on measuring fractional ice volume, a key factor in river ice growth models. The central issue is the adequacy of representations of backscatter cross sections of disk shaped frazil particles in a well-established theory of elastic spherical targets. An initial investigation established criteria for the existence of three-frequency solutions capable of providing lognormal statistical descriptions in terms of effective radii. These criteria restricted analyses of available field data with such models to inputs at two-frequencies limiting outputs to: a common effective radius, particle number density and frazil volume. Additional frazil cross section information is shown to be required to more fully exploit the full capability of multi-frequency profiling. An approximate relationship between cross sections and the product of acoustic wavenumbers and particle effective radii (k1ae) is developed from laboratory polystyrene disk and sphere data and transformed into the natural ice environment. Field data within the transformed range is transposed to higher frequencies in order to allow testing at still larger field values of k1ae. Two-frequency analyses utilizing the resulting “pseudo-frazil” relationship confirmed a close match with the field data and increased compatibility with existence criteria for three-frequency solutions. The results showed that, within transducer calibration limits, the originally tested spherical backscattering extractions consistently under-estimate frazil ice volume concentrations by 25 % confirming its continued use for accurate estimates in conjunction with a constant scaling factor of about 1.25.

Three-dimensional depth-to-basement modelling based on seismic and potential field data – basement configuration in the westernmost Polish Outer Carpathians

2020 ◽  
Author(s):  
Mateusz Mikołajczak ◽  
Jan Barmuta ◽  
Małgorzata Ponikowska ◽  
Stanislaw Mazur ◽  
Krzysztof Starzec
Keyword(s):  
Qualitative Analysis ◽  
Cross Sections ◽  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Three Dimensional ◽  
Magnetic Data ◽  
Gravity Inversion ◽  
Potential Field Data ◽  
Outer Carpathians

<p>The Silesian Nappe in the westernmost part of the Polish Outer Carpathians Fold and Thrust Belt exhibits simple, almost homoclinal character. Based on the field observations, a total stratigraphic thickness of this sequence equals to at least 5400 m. On the other hand, the published maps of the sub-Carpathian basement show its top at depths no greater than 3000 m b.s.l. or even 2000 m b.s.l. in the southern part of the Silesian Nappe. Assuming no drastic thickness variations within the sedimentary sequence of the Silesian Nappe, such estimates of the basement depth are inconsistent with the known thickness of the Silesian sedimentary succession. The rationale behind our work was to resolve this inconsistency and verify the actual depth and structure of the sub-Carpathian crystalline basement along two regional cross-sections. In order to achieve this goal, a joint 2D quantitative interpretation of gravity and magnetic data was performed along these regional cross-sections. The interpretation was supported by the qualitative analysis of magnetic and gravity maps and their derivatives to recognize structural features in the sub-Carpathian basement. The study was concluded with the 3D residual gravity inversion for the top of basement. The cross-sections along with the borehole data available from the area were applied to calibrate the inversion.</p><p>In the westernmost part of the Polish Outer Carpathians, the sub-Carpathian basement comprises part of the Brunovistulian Terrane. Because of great depths, the basement structure was investigated mainly by geophysical, usually non-seismic, methods. However, some deep boreholes managed to penetrate the basement that is composed of Neoproterozoic metamorphic and igneous rocks. The study area is located within the Upper Silesian block along the border between Poland and Czechia. There is a basement uplift as known mainly from boreholes, but the boundaries and architecture of this uplift are poorly recognized. Farther to the south, the top of the Neoproterozoic is buried under a thick cover of lower Palaeozoic sediments and Carpathian nappes.</p><p>Our integrative study allowed to construct a three-dimensional map for the top of basement the depth of which increases from about 1000 m to over 7000 m b.s.l. in the north and south of the study area, respectively. Qualitative analysis of magnetic and gravity data revealed the presence of some  basement-rooted faults delimiting the extent of the uplifted basement. The interpreted faults are oriented mainly towards NW-SE and NE-SW. Potential field data also document the correlation between the main basement steps and important thrust faults.</p><p> </p><p>This work has been funded by the Polish National Science Centre grant no UMO-2017/25/B/ST10/01348</p>

scholarly journals Analysis of ice phenomena hazard on the middle Odra river

2017 ◽  
Vol 49 (4) ◽  
pp. 301-314 ◽  
Author(s):  
Krzysztof Wolski ◽  
Tomasz Tymiński ◽  
Beata Głuchowska
Keyword(s):  
Water Management ◽  
Cross Sections ◽  
Reference Data ◽  
Life Sciences ◽  
Ice Cover ◽  
Frazil Ice ◽  
Ice Jam ◽  
Odra River ◽  
Regional Water ◽  
Ice Phenomena

Abstract The paper contains analysis of ice phenomena occurrence in the light of recent observations conducted on middle Odra river from Krapkowice (ca. km 125+000) to Krosno Odrzańskie (ca. km 530+000). In detail the research embraced time of occurrence and intensity of individual ice phenomena in years 2006–2017 together with reference and comparison of data to previous data from period 1957–2005. In characteristic cross-sections there is a reference to occurrence of all observed forms of ice phenomena (frazil ice, border ice, ice cover, floe and ice-jam). In the study a reference data of Regional Water Management Authority in Wrocław were used together with results of previous research conducted at the Wrocław University of Environmental and Life Sciences. The results legitimized, that the occurrence of ice phenomena on middle Odra river has time of its appearance, duration and intensity and is not stable in every year. Occurrence of ice phenomena on middle Odra river varies in time, being observed as manifold forms of icing – most frequently border ice and frazil ice. During the last 12 years greater than the average number of days with ice phenomena occurrence can be observed, but these phenomena have definitely “milder” character (border ice).

Numerical Finger Kinematic Models Derived From Virtual Grasping of Various Cylindrical Objects With the Family of Conic Sections

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Jong-Seob Won ◽  
Reza Langari ◽  
Nina Robson
Keyword(s):  
Cross Sections ◽  
Numerical Models ◽  
Model Development ◽  
Human Hand ◽  
Conic Sections ◽  
Joint Rotation ◽  
Flexion Extension ◽  
The Family ◽  
Specific Contact ◽  
The Individual

Abstract In this study, a numerical framework for joint rotation configuration models of a finger is proposed. The basic idea is to replicate the finger’s geometric posture observed when the human hand grasps a cylindrical object with various cross sections. In the model development, objects with the cross section adopted from the curves of order two (the family of conic sections) are taken into consideration to realize various finger postures. In addition, four different grasp styles, which simulate the individual-specific contact pattern between the surfaces of object and finger, are modeled and applied for the formulation of numerical models. An idea on how to change flexion/extension patterns in the middle of excursion of movement is proposed and discussed. Series of numerical studies have been conducted and analyzed to evaluate the proposed models. From the results, one can see the models’ feasibility and viability as a solution to describing finger’s flexion/extension movements (FEMs) for grasping patterns.

Statistical Initiation and Crack Growth Models for Stress Corrosion Cracking

2007 ◽  
Author(s):  
W. J. Shack ◽  
O. K. Chopra
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Field Data ◽  
Growth Models ◽  
Statistical Distributions ◽  
Parametric Dependencies ◽  
Component Failure Rates ◽  
The Times ◽  
Crack Growth Rates

Statistical distributions of initiation times and crack growth rates are needed for probabilistic fracture mechanics models. Times to failure in laboratory tests on small specimens are about a factor of 1000 shorter than the times to failure of comparably sized “specimens” in the field would have to be in order to get realistic component failure rates. Thus while specimen tests are useful in identifying parametric dependencies, it is unlikely that they can be used directly to develop initiation models for field components without using field data. A scaling approach is proposed to provide a method for pooling data from different size components and for extrapolating experience from one set of components to another set. Estimates of statistical distributions for initiation of stress corrosion cracks are developed from field data for BWR pipe cracking and CRDM cracking. Estimates of statistical distributions of crack growth rates are developed by combining phenomenological models for crack growth rates with expert judgment on the range of input parameters to those models.

scholarly journals ESTABLISHING ENGINEERING S-CURVES TO EVALUATE SUPERVISION ENGINEER ALLOCATIONS FOR HIGHWAY CONSTRUCTION PROJECTS

2016 ◽  
Vol 22 (7) ◽  
pp. 890-902
Author(s):  
Shih-Hsu WANG ◽  
Wei-Chih WANG ◽  
Pei-Yuan HSU ◽  
Ci-Hao CHEN ◽  
Kun-Chi WANG
Keyword(s):  
Cluster Analysis ◽  
Quality Assurance ◽  
Construction Projects ◽  
Model Development ◽  
Highway Construction ◽  
Stage Model ◽  
Planning Stage ◽  
Curve Model ◽  
Key Factor

An engineering consultant firm needs to allocate engineers to supervise a highway construction project in each month during the construction phase. Properly assigning the supervision engineers under a cost-plus-fixed-fee contract has been a key factor affecting the profitability of the firm and the quality assurance of the project. Assigning too many engineers will be a waste, while allocating too few engineers may harm the supervision quality. This work proposes a two-stage model to develop engineering S-curves (called ES-curves) for planning and controlling the engineering super­vision schedule. In the planning stage, a predictive ES-curve model is established based on historical ES-curves. In the controlling stage, an ES-curve is built according to the relationships between the engineering progress and construction progress. A cluster analysis and regression analysis are applied to the model development. A case study demonstrates that the produced ES-curves can help management in planning and evaluating when to increase or decrease the number of supervision engineers assigned to a project.

scholarly journals Volumetric variations of Glacier de Sarennes, French Alps, during the last two centuries

1997 ◽  
Vol 24 ◽  
pp. 361-366
Author(s):  
François Valla ◽  
Christian Piedallu
Keyword(s):  
Computer Program ◽  
Mass Balance ◽  
Cross Sections ◽  
Little Ice Age ◽  
Snow Accumulation ◽  
Ice Age ◽  
Ice Thickness ◽  
Reasonable Accuracy ◽  
French Alps ◽  
Ice Volume

Glacier de Sarennes, located in the heart of the French Alps, has been observed closely since 1906 and regularly measured (snow accumulation, ablation and mass balance) since 1948. Several publications have stemmed from this research, such as the 1906 and 1958 glaciological maps and the 1981 and 1991 photogrammetric analyses. In 1992, a field radar campaign determined the ice thickness and allowed the drawing of the bedrock map with reasonable accuracy. The Little Ice Age stage was reconstructed with the bedrock tracks, in 1995.The above-mentioned documents were digitized, and the computer program Arc-Info permitted the calculation of the successive volume stages occupied by the glacier from 1850 to 1991. Cross-sections and slope profiles illustrate the evolution of the thickness of Glacier de Sarennes during the last 150 years. All of these results, consistent with the variation of the mass balance observed or estimated, show the main conclusion: compared with today, the glacier was about four times more voluminous 90 years ago (i.e. it has lost three-quarters of its ice volume) and five times bigger one and a half centuries ago.

Digital inclusion in later life: cohort changes in internet use over a ten-year period in England

2018 ◽  
Vol 39 (9) ◽  
pp. 1914-1932 ◽  
Author(s):  
KATEY MATTHEWS ◽  
JAMES NAZROO ◽  
ALAN MARSHALL
Keyword(s):  
Older People ◽  
Internet Use ◽  
Growth Models ◽  
Later Life ◽  
The Internet ◽  
Digital Inclusion ◽  
Age Cohort ◽  
Key Factor ◽  
Digital Exclusion ◽  
English Longitudinal Study

ABSTRACTThe ability to use the internet frequently is likely to provide a useful means of engaging with society and using services in later life, yet older people are the most likely to suffer digital exclusion, with those of the oldest ages at the greatest risk. Using six waves (2002–2012) of the English Longitudinal Study of Ageing, we model cohort-specific patterns of frequent internet use for people aged 50 and over. Multi-level growth models are used to observe trajectories of internet use over the ten-year period. Firstly, analyses are stratified by gender and wealth, and secondly we additionally test for health effects. The study finds cohort-specific differences in patterns of internet use. Rates of internet use increase faster among younger cohorts yet, despite initially increasing, begin to decline among older cohorts. Poor health is shown to be a key factor in shaping the trajectory of internet use over time. Rates of internet use are consistently lower for women than men and for those in poorer financial circumstances, independently of age cohort. The findings demonstrate the importance of ensuring older people can remain digitally included throughout later life, including after the onset of poorer health, especially as some of these individuals might benefit the most from some of the services the internet can provide.

scholarly journals Structures of the Kirkuk Embayment, northern Iraq: Foreland structures or Zagros Fold Belt structures?

GeoArabia ◽  
2010 ◽  
Vol 15 (4) ◽  
pp. 147-188 ◽  
Author(s):  
W. Norman Kent
Keyword(s):  
Cross Sections ◽  
Seismic Data ◽  
Field Data ◽  
Fault System ◽  
Normal Faults ◽  
Fold Belt ◽  
Potential Field Data ◽  
Northern Iraq ◽  
Fault Propagation Fold ◽  
Zagros Orogen

ABSTRACT Several anticlines in northern Iraq and Syria have been studied through the construction of balanced and restored cross sections. Based upon structural analysis, each of the studied anticlines is a fault-propagation fold that developed due to Zagros-related, recent inversion of much older normal faults. Studies on the Iranian part of the Zagros Fold Belt have suggested that the regional variation in the character of the fold belt is related to weak detachment surfaces in the stratigraphic section, primarily the decollement developed near the top of the Hormuz Salt where the salt is present. No evidence for Hormuz Salt has been found within the Kirkuk Embayment, and although detachment surfaces contribute the area’s structural character, the prominent folds seem to originate mainly from basement involved faults. Two distinct inversion structural trends exist: E-W system and a NW system of inverted grabens. In Syria, several of the faults associated with the EW-trending system cut the basement on seismic data and have stratigraphic relationships indicating that their displacement originated in the Neoproterozoic. In Iraq, the thicker sedimentary section did not allow the deep parts of the fault systems to be imaged on the available seismic. While the NW fault system of inverted normal faults could be linked to the Zagros Orogen by a decollement surface in the sedimentary section, regional relationships and potential-field data suggest that this trend also is basement involved and has a Neoproterozoic origin.

Model development and validation of electrospun jet formation

2018 ◽  
Vol 89 (11) ◽  
pp. 2177-2186 ◽  
Author(s):  
Yuansheng Zheng ◽  
Binjie Xin ◽  
Masha Li
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Model Development ◽  
Electrospinning Process ◽  
Taylor Cone ◽  
Jet Formation ◽  
Velocity Magnitude ◽  
Key Factor ◽  
Simulation Results ◽  
Development And Validation

The Taylor cone formed at the tip of the syringe used for delivering the solution plays an important role in jet formation. This study presents a novel multiphysics model to simulate the dynamic processes occurring within the cone jet from a flat spinneret and a single needle spinneret. The electric field, volume fraction and velocity magnitude of the polymer jet ejecting from two different kinds of spinnerets are calculated by the multiphysics simulation model. A high-speed camera is employed to capture the jet formed by the Taylor cone. The simulation results are validated by comparison with experimental results. It is found that the spinneret configuration could be the key factor in determining cone morphology in the electrospinning process.

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