Visualization of Scouring Behavior around Bottom Edge of Discharging Plates in a Channel with Discharging Plates

2021 ◽  
Vol 2021.74 (0) ◽  
pp. A12
Author(s):  
Yu NAKAMURA ◽  
Minoru FUKUHARA ◽  
Mitsuhiro NAKAO
Keyword(s):  
Bottom Edge

scholarly journals Stent technique for endoscopic dacryocystorhinostomy – Our expertise

2016 ◽  
Vol 6 (21) ◽  
pp. 23-27
Author(s):  
Vlad Budu ◽  
Tatiana Decuseara ◽  
Bogdan Mocanu ◽  
Raluca Baican ◽  
Mihai Tusaliu ◽  
...  
Keyword(s):  
Success Rate ◽  
Lacrimal Sac ◽  
Lacrimal Duct ◽  
Bottom Edge ◽  
Duct Obstruction ◽  
Endoscopic Dacryocystorhinostomy ◽  
Lacrimal Apparatus ◽  
The Mean ◽  
Surgery Department ◽  
The Ideal

Abstract BACKGROUND. Endoscopic dacryocystorhinostomy is known to be the ideal treatment for saccal and postsaccal stenosis of the lacrimal apparatus. Following this surgery, an important inconvenient would be the stenosis of the created ostium with consecutive epiphora. MATERIAL AND METHODS. 20 patients with chronic unilateral lacrimal duct obstruction were operated in “Prof. Dr. D. Hociota” Institute of Phono-Audiology and Functional ENT Surgery, Department I, between January 2015 and July 2015. After creating the dacryocystorhinostoma, a stent was inserted transnasally to the bottom edge of the lacrimal sac and positioned to the bony margin of the ostium. Stents used varied in size from 1 to 3 mm in diameter. We followed-up our patients at 2 weeks and 1, 3, 6 months, assessing the symptoms of the lacrimal apparatus, especially the epiphora. RESULTS. The mean age of patients varied between 31 and 65. Most of our patients were women (n=14). In a total number of 16 patients epiphora disappeared, it decreased in 2 patients, and persisted in 2 patients. There were two patients with no changes who have spontaneously eliminated the stent 2 or 3 days after the surgery. The most widely used stent size was 3 mm diameter, with a success rate of 90%. CONCLUSION. The endoscopic approach may be an effective procedure in patients with pathologies of the lacrimal apparatus. In order to achieve an efficient result, both a preoperative rigorous preparation and also postoperative medical care are necessary. In conclusion, ostium stenting represents a better way to ensure a longer period of maintaining the permeability of the lacrimal apparatus.

Hydrodynamic Optimization of a Wedge Hull

2015 ◽  
Author(s):  
Lijue Wang ◽  
Fuxin Huang ◽  
Chi Yang ◽  
Raju Datla
Keyword(s):  
Hydrodynamic Performance ◽  
Surface Mesh ◽  
Nurbs Surface ◽  
Bottom Edge ◽  
Hull Form ◽  
Entrance Angle ◽  
Total Drag ◽  
Rounded Corner ◽  
Bulbous Bow ◽  
Hydrodynamic Optimization

A novel wedge-shaped hull form is optimized for reduced drag using a further developed practical hydrodynamic optimization tool. The hull features a sharp entrance angle, rectilinear sides, sharp bottom edges, a triangular waterplane and a linear aftward taper from a deep bow to a shallow transom. The optimization involves two modifications of the hull form, one is to smooth out the sharp bottom edge with a rounded corner and the other is to generate a bulbous bow. In order to perform the hydrodynamic optimization of the hull, a Non-Uniform Rational BSpline (NURBS)-based hull surface modification tool, a NURBS surface mesh generator, a surrogate model and an evolutionary optimization solver are developed and integrated into the practical hydrodynamic optimization tool. The hydrodynamic performances, i.e., the total drag and the flow field near the obtained hull bodies are assessed and compared with the original wedge hull using numerical simulations. Results showed that rounding the sharp edge of the wedge hull can reduce the total drag by alleviating the flow separations around the hull body. The wedge hull with rounded bottom edge and optimized bulbous bow can achieve larger drag reduction and the flow separations are almost eliminated. The total drag of the optimal hull is compared with an earlier-optimized wedge hull that has a different type of bulbous bow, whose hydrodynamic performance has been validated by model tests.

Mechanistic Modeling of Five-Axis Machining With a Flat End Mill Considering Bottom Edge Cutting Effect

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Zhou-Long Li ◽  
Li-Min Zhu
Keyword(s):  
Cutting Forces ◽  
Mechanistic Model ◽  
Mechanistic Modeling ◽  
End Mill ◽  
Bottom Edge ◽  
Radial Line ◽  
Bottom Part ◽  
Lead Angle ◽  
Cutting Effect ◽  
Five Axis

In five-axis milling, the bottom edge of a flat end mill is probably involved in cutting when the lead angle of tool axis changes to negative. The mechanistic model will lose accuracy if the bottom edge cutting effect is neglected. In this paper, an improved mechanistic model of five-axis machining with a flat end mill is presented to accurately predict cutting forces by combining the cutting effects of both side and bottom edges. Based on the kinematic analysis of the radial line located at the tool bottom part, the feasible contact radial line (FCRL) is analytically extracted. Then, boundaries of the bottom cutter-workpiece engagements (CWEs) are obtained by intersecting the FCRL with workpiece surfaces and identifying the inclusion relation of its endpoints with the workpiece volume. Next, an analytical method is proposed to calculate the cutting width and the chip area by considering five-axis motions of the tool. Finally, the method of calibrating bottom-cutting force coefficients by conducting a series of plunge milling tests at various feedrates is proposed, and the improved mechanistic model is then applied to predict cutting forces. The five-axis milling with a negative lead angle and the rough machining of an aircraft engine blisk are carried out to test the effectiveness and practicability of the proposed model. The results indicate that it is essential to take into account the bottom edge cutting effect for accurate prediction of cutting forces at tool path zones where the tool bottom part engages with the workpiece.

scholarly journals The influence of midwater hypoxia on nekton vertical migration

2009 ◽  
Vol 66 (6) ◽  
pp. 1296-1302 ◽  
Author(s):  
Sandra L. Parker-Stetter ◽  
John K. Horne ◽  
Mariko M. Langness
Keyword(s):  
Vertical Migration ◽  
Bottom Edge ◽  
Prey Refuge ◽  
Upward Migration ◽  
Hood Canal ◽  
Vertical Distributions ◽  
Water Ecosystems ◽  
Bottom Hypoxia ◽  
Pelagic Nekton ◽  
Oxygen Minimum

Abstract Parker-Stetter, S. L., Horne, J. K., and Langness, M. M. 2009. The influence of midwater hypoxia on nekton vertical migration. – ICES Journal of Marine Science, 66: 1296–1302. Hypoxia affects pelagic nekton, fish and large zooplankton, distributions in marine and fresh-water ecosystems. Bottom hypoxia is common, but midwater oxygen minimum layers (OMLs) may also affect nekton that undergo diel vertical migration (DVM). This study examined the response of pelagic nekton to an OML in a temperate fjord (Hood Canal, WA, USA). A 2006 study suggested that the OML created a prey refuge for zooplankton. Using acoustics (38 and 120 kHz), the 2007 night DVM patterns of nekton were quantified before (June, August) and during (September) an OML. All months had similar precrepuscular distributions (>50-m depth) of fish and invertebrates. During the September evening crepuscular period, a zooplankton layer migrated upwards (>1.5 m min−1), but the layer's rate of ascent slowed to <0.5 m min−1 when it reached the lower edge of the OML. The bottom edge of the layer then moved below the OML and remained there for 13 minutes before moving through the OML at >1.0 m min−1. As in June and August, fish in September followed the upward migration of the zooplankton layer to the surface, crossing through the OML. Our results suggest that the 2007 OML did not affect zooplankton or fish vertical distributions.

BUCKLING OF STANDING VERTICAL PLATES UNDER BODY FORCES

2002 ◽  
Vol 02 (02) ◽  
pp. 151-161 ◽  
Author(s):  
C. M. WANG ◽  
Y. XIANG ◽  
C. Y. WANG
Keyword(s):  
Boundary Conditions ◽  
Vertical Plate ◽  
Ritz Method ◽  
Elastic Buckling ◽  
Bottom Edge ◽  
Simply Supported ◽  
Body Forces ◽  
Two Sides

This paper is concerned with the elastic buckling problem of vertical plates under body forces/selfweight. The vertical plate is either clamped or simply supported at its bottom edge while its top edge is free. The two sides of the plate may either be free, simply supported or clamped. For plates with simply supported sides, exact critical buckling solutions are derived using the Levy approach. For other boundary conditions, accurate buckling solutions are obtained for very wide plates to very tall plates using the Ritz method.

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