scholarly journals HYDRAULICS AND SEDIMENTARY STABILITY OF COASTAL INLETS

1972 ◽  
Vol 1 (13) ◽  
pp. 38 ◽  
Author(s):  
M.P. O'Brien ◽  
R.G. Dean
Keyword(s):  
Cross Section ◽  
Stability Index ◽  
Hydraulic Loss ◽  
Cross Sectional ◽  
Equilibrium Relationship ◽  
Depositional Patterns ◽  
Storage Area ◽  
Loss Coefficients ◽  
The Stability ◽  
Coastal Inlets

A method is presented for investigating the stability of coastal inlets against closure due to transport and deposition of sand in the inlet cross-section. The method utilizes earlier contributions by: (1) Keulegan representing the hydraulics of inlets, (2) O'Brien which describes an equilibrium relationship between the cross-sectional area of an inlet and the bay tidal prism, and (3) Escoffier which relates to the stability of an inlet under changes in conditions which tend to close or enlarge an inlet. A "stability index" is defined which incorporates the buffer storage area available in the inlet cross-section, prior to the onset of closure and also includes the capability of the inlet to transport excess sand from its cross-section. In order to apply the method, geometric and hydraulic data representing the inlet are necessary; the minimum data required include a survey of the inlet throat cross-section and the lag between high (or low) water in the ocean and the following slack water in the inlet. In addition, it is necessary to conduct measurements or make assumptions concerning the minor and gradual hydraulic loss coefficients. Based on assumed depositional patterns in the inlet, the method is applied to five real inlets and the stability indices are presented.

scholarly journals Numerical simulation of cutting layer in internal corners milling

Mechanik ◽  
2019 ◽  
Vol 92 (7) ◽  
pp. 412-414
Author(s):  
Jan Burek ◽  
Rafał Flejszar ◽  
Barbara Jamuła
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Cross Section ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Cross Section Area ◽  
Section Area ◽  
The Cross ◽  
The Stability

The analytical and numerical model of the cross-section of the machined layer in the process of milling of concave rounding is presented. Simulation tests were carried out to determine the cross-sectional area of the cutting layer. A strategy has been developed that allows to increase the stability of the cross-section area of the cutting layer when the mill enters the inner corner area.

On the stability of flow in an elliptic pipe which is nearly circular

1994 ◽  
Vol 281 ◽  
pp. 357-369 ◽  
Author(s):  
A. Davey ◽  
H. Salwen
Keyword(s):  
Cross Section ◽  
Specific Problem ◽  
Sectional Area ◽  
Leading Order ◽  
Straight Pipe ◽  
Cross Sectional ◽  
Double Eigenvalue ◽  
Circular Problem ◽  
Qualitative Structure ◽  
The Stability

In an earlier paper (Davey 1978) the first author investigated the linear stability of flow in a straight pipe whose cross-section was an ellipse, of small ellipticity e, by regarding the flow as a perturbation of Poiseuille flow in a circular pipe. That paper contained some serious errors which we correct herein. We show analytically that for the most important mode n = 1, for which the circular problem has a double eigenvalue c0 as the ‘swirl’ can be in either direction, the ellipticity splits the double eigenvalue into two separate eigenvalues c0 ± e2c12, to leading order, when the cross-sectional area of the pipe is kept fixed. The imaginary part of c12 is non-zero and so the ellipticity always makes the flow less stable. This specific problem is generic to a much wider class of fluid dynamical problems which are made less stable when the symmetry group of the dynamical system is reduced from S1 to Z2.In the Appendix, P. G. Drazin describes simply the qualitative structure of this problem, and other problems with the same symmetries, without technical detail.

On the stability of liquid ridges

1999 ◽  
Vol 391 ◽  
pp. 293-318 ◽  
Author(s):  
R. VALÉRY ROY ◽  
LEONARD W. SCHWARTZ
Keyword(s):  
Contact Angle ◽  
Cross Section ◽  
Energy Functional ◽  
Liquid Region ◽  
Contact Lines ◽  
Property A ◽  
Cross Sectional ◽  
Elliptical Cross ◽  
Special Cases ◽  
The Stability

We consider the stability of a rectilinear liquid region whose boundary is composed of a solid cylindrical substrate of arbitrary shape and a free surface whose cross-section, in the absence of gravity, is a circular arc. The liquid–solid contact angle is a prescribed material property. A variational technique, using an energy functional, is developed that predicts the minimum wavelength for transverse instability under the action of capillarity. Conversely, certain configurations are absolutely stable and a simple stability criterion is derived. Stability is guaranteed if, for given substrate geometry and given contact angle, the unperturbed meniscus pressure is an increasing function of the liquid cross-sectional area. The analysis is applied to a variety of liquid/substrate configurations including (i) a liquid ridge with contact lines pinned to the sharp edges of a slot or groove, (ii) liquid ridges with free contact lines on flat and wedge-shaped substrates as well as substrates of circular or elliptical cross-section. Results are consistent with special cases previously treated including those that employ a slope-small-slope approximation.

Optimization of High Concrete Retaining Wall Structure

2013 ◽  
Vol 357-360 ◽  
pp. 597-603
Author(s):  
Su Yang Gao ◽  
Yan Chen ◽  
Yao Feng Xie ◽  
Wen Dong Lei ◽  
Kai Yin
Keyword(s):  
Cross Section ◽  
Optimization Design ◽  
Retaining Wall ◽  
Cross Sectional Area ◽  
Wall Structure ◽  
Sectional Area ◽  
Cross Sectional ◽  
Structure Selection ◽  
Great Height ◽  
The Stability

The height of vertical pier retaining wall is relatively larger in regions with great height of water. As the retaining wall becomes higher, the cross-sectional area of ordinary gravity pier structure becomes larger and foundation strength needs to be larger, thus there are some restrictions for traditional structure form. This research focuses on new structure forms of high concrete retaining wall and its optimization design for piers in regions with great height of water. This study establishes a nonlinear constrained mathematical model of pier high retaining wall structures. The objective function is cross-sectional area of the pier retaining wall which is restricted by the stability, bearing capacity of foundation and strength of cross-section of retaining wall. This model is solved by fmincon function from Matlab and the results present an economically reasonable cross-section form. This new selection is greatly significant to improve the stability of high concrete retaining wall and reduce the project cost. The new structure is successfully used in a port of Huaihe River and it can be a solution to pier structure selection problem in regions with great height of water in the future.

The Finite Element Analysis of Ultimate Bearing Capacity of Initial Bending on the T-Axis Compression Component

2013 ◽  
Vol 690-693 ◽  
pp. 1914-1918
Author(s):  
Yang Yang Han ◽  
Cai Xia Zhang ◽  
Ya Qin Li ◽  
Si Yu Chen ◽  
Chun Shan Liu
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Cross Section ◽  
Element Calculation ◽  
Element Analysis ◽  
Cross Sectional ◽  
Buckling Behavior ◽  
The Finite Element Analysis ◽  
Axis Compression ◽  
The Stability

There is little research about the stability of T-stub steel axial compression component at home and abroad, and it remains to further investigation. On the basis of taking initial bending and other factors into consideration, through theoretical analysis and finite element calculation, this paper studies the T-stub steel axial compression buckling behavior and carrying capacity mainly using three different cross-section and different lengths ZC cross-sectional specimens.

Flow Structures and Their Relevance to Passive Scalar Transport in Fume Cupboards

1993 ◽  
Vol 207 (2) ◽  
pp. 103-115 ◽  
Author(s):  
İB Özdemir ◽  
J H Whitelaw ◽  
A F Biçen
Keyword(s):  
Cross Section ◽  
Passive Scalar ◽  
Scalar Transport ◽  
External Disturbances ◽  
Cross Sectional ◽  
Passive Scalar Transport ◽  
Air Stream ◽  
Cross Sectional Dimension ◽  
Spanwise Vortex ◽  
The Stability

This paper describes an experimental investigation of air flow patterns and related passive scalar transport inside an open-fronted containment facility, with emphasis on the interaction with the laboratory environment. Time-averaged and instantaneous structures of the turbulent flow were examined by visualization and local measurements inside the enclosure and at the front aperture of 1200 mm × 500 mm cross-section. The cabinet was scavenged at an extract flowrate of 0.310 m3/s with 95 per cent of the air passing through the front aperture at a spatially averaged air velocity of 0.5 m/s and 5 per cent supplied through an auxiliary aperture of 1200 mm × 15 mm cross-section located at the front edge of the ceiling of the enclosure. Sulphur hexafluoride was used to mark the flow and the distributions of its time-averaged concentration over the front aperture and inside the cabinet were used to deduce the degree of mixing and passive scalar transport. The geometrical features of the cabinet provided a flow field with a spanwise vortex at the upper frontal part of the enclosure, whose cross-sectional dimension was larger close to the side walls where the velocity of the inflowing air was lower than in the central region. The spanwise vortex implemented to improve capture efficiency at low inflowing air velocities can be detrimental to the stability of the inflowing air stream along the sash handle, leading to severe leakage of the passive scalar encapsulated within the vortex itself. Without external disturbances, the leakage from the vortex occurs with the periodic bursts generated by the oscillations at the periphery of the spanwise vortex, but these oscillations become more random with the cross-draught. The structure and the orientation of the vortex were vulnerable to external disturbances in that the vortex was tilted and pushed below the sash level on one side, resulting in asymmetrical leakage.

Explicit Solutions for the Stability of No-Tension Beam-Columns

2003 ◽  
Vol 03 (02) ◽  
pp. 195-213 ◽  
Author(s):  
A. de Falco ◽  
M. Lucchesi
Keyword(s):  
Differential Equations ◽  
Cross Section ◽  
Axial Load ◽  
Explicit Solutions ◽  
Cross Sectional ◽  
Beam Columns ◽  
The Cross ◽  
The Stability ◽  
No Tension Material ◽  
Explicit Relation

This work concerns the stability of rectangular cross-sectional piles made of a no-tension material and subjected to an axial load acting at the extremities within the middle third of the cross section. The resulting differential equations are solved, and an explicit relation between the load and a suitable deformability parameter obtained.

Mass Determination by Direct Measurement of Electron Scattering

1975 ◽  
Vol 33 ◽  
pp. 240-241
Author(s):  
M. K. Lamvik ◽  
A. V. Crewe
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Mass Density ◽  
Variable Mass ◽  
Scattering Cross Section ◽  
Mass Determination ◽  
Number Density ◽  
Cross Sectional ◽  
Thin Slice ◽  
Scattering Cross

If a molecule or atom of material has molecular weight A, the number density of such units is given by n=Nρ/A, where N is Avogadro's number and ρ is the mass density of the material. The amount of scattering from each unit can be written by assigning an imaginary cross-sectional area σ to each unit. If the current I0 is incident on a thin slice of material of thickness z and the current I remains unscattered, then the scattering cross-section σ is defined by I=IOnσz. For a specimen that is not thin, the definition must be applied to each imaginary thin slice and the result I/I0 =exp(-nσz) is obtained by integrating over the whole thickness. It is useful to separate the variable mass-thickness w=ρz from the other factors to yield I/I0 =exp(-sw), where s=Nσ/A is the scattering cross-section per unit mass.

A tilting high temperature gas reaction chamber for the JEM 7A T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 70-71
Author(s):  
Brian L. Rhoades
Keyword(s):  
Cross Section ◽  
Reaction Chamber ◽  
Objective Lens ◽  
Reduced Cross Section ◽  
Cross Sectional ◽  
Structural Investigations ◽  
Transmission Electron ◽  
Dynamic Experiments ◽  
Successful Design ◽  
Thermocouple Junction

A gas reaction chamber has been designed and constructed for the JEM 7A transmission electron microscope which is based on a notably successful design by Hashimoto et. al. but which provides specimen tilting facilities of ± 15° aboutany axis in the plane of the specimen.It has been difficult to provide tilting facilities on environmental chambers for 100 kV microscopes owing to the fundamental lack of available space within the objective lens and the scope of structural investigations possible during dynamic experiments has been limited with previous specimen chambers not possessing this facility.A cross sectional diagram of the specimen chamber is shown in figure 1. The specimen is placed on a platinum ribbon which is mounted on a mica ring of the type shown in figure 2. The ribbon is heated by direct current, and a thermocouple junction spot welded to the section of the ribbon of reduced cross section enables temperature measurement at the point where localised heating occurs.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

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