scholarly journals Parameterization of lateral drag in flowline models of glacier dynamics

2012 ◽  
Vol 58 (212) ◽  
pp. 1119-1132 ◽  
Author(s):  
Surendra Adhikari ◽  
Shawn J. Marshall
Keyword(s):  
Rocky Mountains ◽  
Three Dimensional ◽  
Correction Factors ◽  
Canadian Rocky Mountains ◽  
Horizontal Shear ◽  
Cross Sectional ◽  
Shape Factors ◽  
Bed Topography ◽  
Valley Glacier ◽  
Basal Flow

Given the cross-sectional geometry of a valley glacier, effects of lateral drag can be parameterized in flowline models through the introduction of Nye shape factors. Lateral drag also arises due to lateral variability in bed topography and basal flow, which induce horizontal shear stress and differential ice motion. For glaciers with various geometric and basal conditions, we compare three-dimensional Stokes solutions to flowline model solutions to examine both sources of lateral drag. We calculate associated correction factors that help flowline models to capture the effects of lateraldrag. Such parameterizations provide improved simulations of the dynamics of narrow, channelized, fast-flowing glacial systems. We present an example application for Athabasca Glacier in the Canadian Rocky Mountains.

I.—Notes On Specimens Collected By Professor Collie, F.R.S., in the Canadian Rocky Mountains

1903 ◽  
Vol 10 (7) ◽  
pp. 289-298
Author(s):  
T. G. Bonnet
Keyword(s):  
Rocky Mountains ◽  
Canadian Rocky Mountains ◽  
Fine Grained ◽  
Valley Glacier ◽  
Southern Side ◽  
Canadian Pacific Railway

The most interesting series of specimens in this collection comes from Desolation Valley glacier, on the southern side of the Canadian Pacific Railway, and east of the watershed. These are: (1) A roughly pentagonal slab, about 9½″ by 7″ and from ¾″ to 1″ thick, of a rather fine-grained quartzite, with some minute glittering crystals, but giving little or no effervescence with cold HCl. The surface is crowded with wavy cylinders, generally slightly flattened, varying in diameter from about ·55″ to ·15″ (but commonly about ·55″).

Process and discharge estimation in ephemeral channels, Canadian Rocky Mountains

1984 ◽  
Vol 21 (9) ◽  
pp. 1050-1060 ◽  
Author(s):  
Joseph R. Desloges ◽  
James S. Gardner
Keyword(s):  
Debris Flow ◽  
Rocky Mountains ◽  
Canadian Rocky Mountains ◽  
Alluvial Channels ◽  
Channel Processes ◽  
Cross Sectional ◽  
Ephemeral Channels ◽  
Multiple Process ◽  
Instantaneous Discharge ◽  
Discharge Estimation

Process determinations and discharge estimates are made for 10 steep alpine channels in the Front and Main ranges of the southern Canadian Rocky Mountains. The catchments, which range in size from 0.17 to 1.13 km2, are sufficiently small that their runoff patterns are dominantly ephemeral and are characterized by processes that include water floods, debris flows, and snow avalanches.Longitudinal and cross-sectional channel profiles demonstrate the importance of bedrock control and the influence of one or more dominant processes. Debris flow channels have been partially scoured by water floods, and avalanche and debris flow sediments are noted in modified alluvial channels. The distribution and sorting of sediments support the multiple-process origin of specific channels or channel reaches.The discrimination of channel processes is essential for estimates of channel discharge. Slope/area and competence methods employed in fluvially dominated reaches of the 10 channels yield maximum instantaneous discharge estimates of between 1.1 and 12.2 m3 s−1. These discharges are generally not representative of the potential volumes of water and sediment released from the channels because of augmentation by both debris flow and avalanche processes. The design of roads and railways traversing these channels requires consideration of a range of processes of varying magnitudes.

scholarly journals Dendroglaciological investigations at Hilda Creek rock glacier, Banff National Park, Canadian Rocky Mountains

2002 ◽  
Vol 53 (3) ◽  
pp. 365-371 ◽  
Author(s):  
Rae Carter ◽  
Sean LeRoy ◽  
Trisalyn Nelson ◽  
Colin P. Laroque ◽  
Dan J. Smith
Keyword(s):  
Tree Ring ◽  
Rocky Mountains ◽  
National Park ◽  
Ground Surface ◽  
Canadian Rocky Mountains ◽  
Rock Glacier ◽  
Tree Ring Chronology ◽  
Cross Sectional ◽  
Engelmann Spruce ◽  
Banff National Park

Abstract Dendroglaciological techniques are used to provide evidence of historical rock glacier activity at Hilda Creek rock glacier in the Canadian Rockies. The research focuses on the sedimentary apron of the outermost morainal deposit, where excavations in 1997 uncovered six buried tree boles that had been pushed over and entombed by distally spilled debris. Cross-sectional samples cross- dated with a local Engelmann spruce tree-ring chronology were shown to have been killed sometime after 1856. Based on the extent of the excavation, the data indicate that Hilda Creek rock glacier has continued to advance along the present ground surface at a rate exceeding 1 cm/year.

Conductive structures under the Canadian Rocky Mountains

1985 ◽  
Vol 22 (3) ◽  
pp. 384-398 ◽  
Author(s):  
D. K. Bingham ◽  
D. I. Gough ◽  
M. R. Ingham
Keyword(s):  
Rocky Mountains ◽  
Transfer Functions ◽  
Three Dimensional ◽  
Vertical Component ◽  
Rocky Mountain ◽  
Auroral Zone ◽  
Event Analysis ◽  
Canadian Rocky Mountains ◽  
Period Range ◽  
Single Station

The paper reports results from an array of 33 three-component magnetometers that recorded time-varying fields in 1981 over an area of some 56 000 km2 in the Canadian Cordillera. The array was centred at Tête Jaune Cache in the Rocky Mountain Trench, where a large magnetovariation anomaly had been located in an earlier array study. It was bisected by the trench and extended to the northeast across the Rocky Mountains to the Alberta Foothills and to the southwest across the Cariboo and Monashee mountains. Magnetograms and Fourier transform maps covering the period range 10–91 min show strong attenuation of the vertical component, Z, southwest of the Rocky Mountain Trench, with very large Z amplitudes in the Main Ranges of the Rockies. The horizontal components show an elongated anomaly along the Rocky Mountains Main Ranges and Trench, with three-dimensional features superimposed. The conductive structures include a highly conductive layer, probably in the lower crust, southwest of the trench and a conductive ridge rising into the upper crust near the edge of that layer. Current models have been fitted to observed vertical -and horizontal-component anomalies and show that both layer and ridge are necessary for a fit and that the ridge is 50–80 km wide. Single-station transfer functions at periods of 10 and 22 min have been calculated from a number of variation events of various polarizations, to reduce any displacement of the anomalies by auroral-zone source currents. Artificial-event analysis, with these transfer functions, shows that the conductive ridge lies under the Main Ranges of the Rockies and not under the trench. Its great width indicates a structure of major tectonic significance, which will be considered in another paper.

scholarly journals Nonlinear water waves in channels of arbitrary shape

1992 ◽  
Vol 242 ◽  
pp. 211-233 ◽  
Author(s):  
Michelle H. Teng ◽  
Theodore Y. Wu
Keyword(s):  
Water Waves ◽  
Arbitrary Shape ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Order Effect ◽  
Equation Model ◽  
Nonlinear Water Waves ◽  
Cross Sectional ◽  
Shape Factors ◽  
Weakly Nonlinear

The generalized channel Boussinesq (gcB) two-equation model and the forced channel Korteweg–de Vries (cKdV) one-equation model previously derived by the authors are further analysed and discussed in the present study. The gcB model describes the propagation and generation of weakly nonlinear, weakly dispersive and weakly forced long water waves in channels of arbitrary shape that may vary both in space and time, and the cKdV model is applicable to unidirectional motions of such waves, which may be sustained under forcing at resonance of the system. These two models are long-wave approximations of a hierarchy set of section-mean conservation equations of mass, momentum and energy, which are exact for inviscid fluids. Results of these models are demonstrated with four specific channel shapes, namely variable rectangular, triangular, parabolic and semicircular sections, in which case solutions are obtained in closed form. In particular, for uniform channels of equal mean water depth, different cross-sectional shapes have a leading-order effect only on the variations of a k-factor of the coefficient of the term bearing the dispersive effects in the model equations. For this case, the uniform-channel analogy theorem enunciated here shows that long waves of equal (mean) height in different uniform channels of equal mean depth but distinct k-shape factors will propagate with equal velocity and with their effective wavelengths appearing k times of that in the rectangular channel, for which k = 1. It also shows that the further channel shape departs from the rectangular, the greater the value of k. Based on this observation, the solitary and cnoidal waves in a k-shaped channel are compared with experiments on wave profiles and wave velocities. Finally, some three-dimensional features of these solitary waves are presented for a triangular channel.

scholarly journals Accuracy and Reproducibility of Facial Measurements of Digital Photographs and Wrapped Cone Beam Computed Tomography (CBCT) Photographs

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 757
Author(s):  
Maged Sultan Alhammadi ◽  
Abeer Abdulkareem Al-mashraqi ◽  
Rayid Hussain Alnami ◽  
Nawaf Mohammad Ashqar ◽  
Omar Hassan Alamir ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Cone Beam Computed Tomography ◽  
High Reliability ◽  
Three Dimensional ◽  
Cone Beam ◽  
Cross Sectional ◽  
Facial Profile ◽  
Digital Photographs ◽  
Gonial Angle

The study sought to assess whether the soft tissue facial profile measurements of direct Cone Beam Computed Tomography (CBCT) and wrapped CBCT images of non-standardized facial photographs are accurate compared to the standardized digital photographs. In this cross-sectional study, 60 patients with an age range of 18–30 years, who were indicated for CBCT, were enrolled. Two facial photographs were taken per patient: standardized and random (non-standardized). The non-standardized ones were wrapped with the CBCT images. The most used soft tissue facial profile landmarks/parameters (linear and angular) were measured on direct soft tissue three-dimensional (3D) images and on the photographs wrapped over the 3D-CBCT images, and then compared to the standardized photographs. The reliability analysis was performed using concordance correlation coefficients (CCC) and depicted graphically using Bland–Altman plots. Most of the linear and angular measurements showed high reliability (0.91 to 0.998). Nevertheless, four soft tissue measurements were unreliable; namely, posterior gonial angle (0.085 and 0.11 for wrapped and direct CBCT soft tissue, respectively), mandibular plane angle (0.006 and 0.0016 for wrapped and direct CBCT soft tissue, respectively), posterior facial height (0.63 and 0.62 for wrapped and direct CBCT soft tissue, respectively) and total soft tissue facial convexity (0.52 for both wrapped and direct CBCT soft tissue, respectively). The soft tissue facial profile measurements from either the direct 3D-CBCT images or the wrapped CBCT images of non-standardized frontal photographs were accurate, and can be used to analyze most of the soft tissue facial profile measurements.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

scholarly journals The patellofemoral morphology and the normal predicted value of tibial tuberosity-trochlear groove distance in the Chinese population

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhe Li ◽  
Guanzhi Liu ◽  
Run Tian ◽  
Ning Kong ◽  
Yue Li ◽  
...  
Keyword(s):  
Individual Differences ◽  
Chinese Population ◽  
Pearson Correlation ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Tibial Tuberosity ◽  
Trochlear Groove ◽  
Lasso Regression ◽  
Cross Sectional ◽  
Anterior Posterior

Abstract Background Our objective was to obtain normal patellofemoral measurements to analyse sex and individual differences. In addition, the absolute values and indices of tibial tuberosity-trochlear groove (TT-TG) distances are still controversial in clinical application. A better method to enable precise prediction is still needed. Methods Seventy-eight knees of 78 participants without knee pathologies were included in this cross-sectional study. A CT scan was conducted for all participants and three-dimensional knee models were constructed using Mimics and SolidWorks software. We measured and analysed 19 parameters including the TT-TG distance and dimensions and shapes of the patella, femur, tibia, and trochlea. LASSO regression was used to predict the normal TT-TG distances. Results The dimensional parameters, TT-TG distance, and femoral aspect ratio of the men were significantly larger than those of women (all p values < 0.05). However, after controlling for the bias from age, height, and weight, there were no significant differences in TT-TG distances and anterior-posterior dimensions between the sexes (all p values > 0.05). The Pearson correlation coefficients between the anterior femoral offset and other indexes were consistently below 0.3, indicating no relationship or a weak relationship. Similar results were observed for the sulcus angle and the Wiberg index. Using LASSO regression, we obtained four parameters to predict the TT-TG distance (R2 = 0.5612, p < 0.01) to achieve the optimal accuracy and convenience. Conclusions Normative data of patellofemoral morphology were provided for the Chinese population. The anterior-posterior dimensions of the women were thicker than those of men for the same medial-lateral dimensions. More attention should be paid to not only sex differences but also individual differences, especially the anterior condyle and trochlea. In addition, this study provided a new method to predict TT-TG distances accurately.

scholarly journals 3D-Volume Rendering of the Pelvis with Emphasis on Paraurethral Structures Based on MRI Scans and Comparisons between 3D Slicer and OsiriX®

2021 ◽  
Vol 45 (3) ◽  
Author(s):  
C. M. Durnea ◽  
S. Siddiqi ◽  
D. Nazarian ◽  
G. Munneke ◽  
P. M. Sedgwick ◽  
...  
Keyword(s):  
Image Processing ◽  
Secondary Analysis ◽  
Three Dimensional ◽  
3D Models ◽  
Clinical Role ◽  
Cross Sectional ◽  
3D Slicer ◽  
Mri Scans ◽  
3D Volume ◽  
Good Agreement

AbstractThe feasibility of rendering three dimensional (3D) pelvic models of vaginal, urethral and paraurethral lesions from 2D MRI has been demonstrated previously. To quantitatively compare 3D models using two different image processing applications: 3D Slicer and OsiriX. Secondary analysis and processing of five MRI scan based image sets from female patients aged 29–43 years old with vaginal or paraurethral lesions. Cross sectional image sets were used to create 3D models of the pelvic structures with 3D Slicer and OsiriX image processing applications. The linear dimensions of the models created using the two different methods were compared using Bland-Altman plots. The comparisons demonstrated good agreement between measurements from the two applications. The two data sets obtained from different image processing methods demonstrated good agreement. Both 3D Slicer and OsiriX can be used interchangeably and produce almost similar results. The clinical role of this investigation modality remains to be further evaluated.

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