scholarly journals An Analysis of Excavation Support Safety Based on Experimental Studies

2015 ◽  
Vol 37 (3) ◽  
pp. 19-29 ◽  
Author(s):  
Karolina Gorska ◽  
Marek Wyjadłowski
Keyword(s):  
Experimental Studies ◽  
Stability Loss ◽  
Numerical Analyses ◽  
Structural Safety ◽  
3D Fem ◽  
Steady Growth ◽  
Excavation Support ◽  
Safety Estimation ◽  
Soldier Pile ◽  
Made In

Abstract The article presents the results of inclinometric measurements and numerical analyses of soldier-pile wall displacements. The excavation under investigation was made in cohesive soils. The measurements were conducted at points located at the edge of the cantilever excavation support system. The displacements of the excavation support observed over the period of three years demonstrated the pattern of steady growth over the first two months, followed by a gradual levelling out to a final plateau. The numerical analyses were conducted based on 3D FEM models. The numerical analysis of the problem comprise calculations of the global structural safety factor depending on the displacement of the chosen points in the lagging and conducted by means of the φ/c reduction procedure. The adopted graphical method of safety estimation is very conservative in the sense that it recognizes stability loss quite early, when one could further load the medium or weaken it by further strength reduction. The values of the Msf factor are relatively high. This is caused by the fact that the structure was designed for excavation twice as deep. Nevertheless, the structure is treated as a temporary one.

scholarly journals Impeller Optimization in Crossflow Hydraulic Turbines

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 313
Author(s):  
Marco Sinagra ◽  
Calogero Picone ◽  
Costanza Aricò ◽  
Antonio Pantano ◽  
Tullio Tucciarelli ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Structural Safety ◽  
3D Fem ◽  
Good Efficiency ◽  
Standard Material ◽  
Variable Head ◽  
Hydraulic Turbines ◽  
Constructive Simplicity ◽  
Mechanical Optimization

Crossflow turbines represent a valuable choice for energy recovery in aqueducts, due to their constructive simplicity and good efficiency under variable head jump conditions. Several experimental and numerical studies concerning the optimal design of crossflow hydraulic turbines have already been proposed, but all of them assume that structural safety is fully compatible with the sought after geometry. We show first, with reference to a specific study case, that the geometry of the most efficient impeller would lead shortly, using blades with a traditional circular profile made with standard material, to their mechanical failure. A methodology for fully coupled fluid dynamic and mechanical optimization of the blade cross-section is then proposed. The methodology assumes a linear variation of the curvature of the blade external surface, along with an iterative use of two-dimensional (2D) computational fluid dynamic (CFD) and 3D structural finite element method (FEM) simulations. The proposed methodology was applied to the design of a power recovery system (PRS) turbine already installed in an operating water transport network and was finally validated with a fully 3D CFD simulation coupled with a 3D FEM structural analysis of the entire impeller.

FURTHER STUDIES ON NATURAL SELECTION AMONG HYBRIDS OF CARDUUS ACANTHOIDES AND CARDUUS NUTANS

1964 ◽  
Vol 42 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
R. J. Moore ◽  
G. A. Mulligan
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Parental Species ◽  
Experimental Studies ◽  
Great Decrease ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Experimental Plots ◽  
Better Than ◽  
Made In

A third 5-year survey made in 1962 of Carduus acanthoides, C. nutans, and their hybrids in Grey Co., Ontario, revealed that a great decrease in these populations had occurred. C. acanthoides and hybrids similar to this species had survived better than C. nutans but very little spread of either species seemed to have occurred in 1957–1962. In experimental plots the hybrid has been made and backcrossed to the parental species. The species differ in chromosome number (C. acanthoides, 2n = 22; C. nutans, 2n = 16) and hybrids have intermediate numbers. Evidence was found from field and experimental studies that the progeny of the F1 hybrid included a greater proportion of seedlings with the higher chromosome numbers than with the lower and intermediate numbers. It is suggested that this selection may operate through the rejection of the longer chromosomes received from C. nutans, which, in certain zygotic combinations may constitute an excess of chromatin lethal to the zygote.

scholarly journals Optimization of plastic foam composition for insulation systems

2019 ◽  
Vol 91 ◽  
pp. 02017 ◽  
Author(s):  
Anton Pilipenko ◽  
Ekaterina Bobrova ◽  
Alexey Zhukov
Keyword(s):  
Heat Loss ◽  
Experimental Studies ◽  
Point Of View ◽  
Structural Safety ◽  
Vapor Permeability ◽  
Building Structures ◽  
Polystyrene Foam ◽  
Building Systems ◽  
Insulation Systems ◽  
Extruded Polystyrene Foam

Construction insulation systems should provide solutions to the problems of creation of suitable conditions of load-bearing construction elements and whole construction, reduction of heat loss through thermal insulation layer, and creation of living comfort in buildings. The article presents the results of experimental studies, the purpose of which is to optimize the composition of extruded polystyrene foam, the formation of methods for selecting its composition and the development of systems for the use of products based on extruded polystyrene foam. Main provisions of the method of analytical optimization, which allows significantly reducing the material and time costs for processing the experimental results, are also provided. Aspects of the implementation of building systems using extruded polystyrene foam both from the point of view of minimizing heat loss through contact areas and the degree of influence of vapor permeability of building structures on the temperature and humidity conditions of premises are studied. Mandatory criteria for construction with the use of building systems are safety conditions, including both structural safety (including maintenance-free cycle) and fire safety.

Validation of Finite Element Lower Extremity Model Using Drop Tower Testing

2013 ◽  
Author(s):  
Robbin Bertucci ◽  
R. Prabhu ◽  
M. F. Horstemeyer ◽  
James Sheng ◽  
Jun Liao ◽  
...  
Keyword(s):  
Finite Element ◽  
Shock Waves ◽  
Lower Extremity ◽  
Cause Of Death ◽  
Direct Contact ◽  
Computational Analysis ◽  
Experimental Studies ◽  
Lower Extremities ◽  
Drop Tower ◽  
Made In

Explosions are the leading cause of death on the battlefield [1]. These explosives, such as bombs and mines, generate shock waves which stimulate large accelerations and deformations. The resulting loads pose serious threats to military and civilians if not sufficiently evaluated and protected. The use of anti-vehicle landmines has become extremely common. Due to lower extremities being in direct contact with the floor of vehicles, the lower extremities are commonly injured during explosions [2]. These injuries can be seriously fatal. Although experimental studies have been performed to advance these understandings [2], limited progress has been made in computational analysis of shock waves on the lower extremity.

scholarly journals Flow structure around an actual willow patch under different depth conditions

2018 ◽  
Vol 40 ◽  
pp. 02049
Author(s):  
Chanjoo Lee ◽  
Donggu Kim ◽  
Sungjung Kim ◽  
Un Ji ◽  
Jihyun Kim ◽  
...  
Keyword(s):  
Flow Measurement ◽  
Flash Flood ◽  
Experimental Studies ◽  
Hydrodynamic Modelling ◽  
Snow Melt ◽  
Key Factors ◽  
Environmental Aspects ◽  
Real Scale ◽  
Natural Channel ◽  
Made In

Vegetation is one of the key factors in river management where environmental aspects as well as flood protection should be taken into consideration. Because of this, numerous studies have been done including experiments and hydrodynamic modelling. Because most of experimental studies were made in indoor laboratory flumes with artificial trees, there are still limitations in transfer of their result to actual channels. REC (River Experiment Center) of Korea has been operating three real-scale, nature-like outdoor experimental channels. In a straight channel, several 4x2 m actual willow patches were planted and have been grown last three years for studies on flow vegetation interaction. A set of intensive flow measurement was made around the first upstream willow patch using ADVs together with measurement of vegetation properties. The experiments were made under several different depth conditions simulating snow-melt and flash-flood. Distribution of flow around and through the patch was characterized along with vertical profiles. The results of the experiment enhance understanding on interaction of flow and actual vegetation in a natural channel and may also provide information on flow resistance used for hydrodynamic modelling and validation.

PRESENT STATUS AND FUTURE PROSPECTS OF HYPERNUCLEAR PHYSICS

2009 ◽  
Vol 24 (11) ◽  
pp. 2101-2109 ◽  
Author(s):  
H. TAMURA
Keyword(s):  
Fine Structure ◽  
Present Status ◽  
Experimental Studies ◽  
Theoretical Development ◽  
Future Prospects ◽  
Great Progress ◽  
Nuclear Systems ◽  
Γ Ray ◽  
Hypernuclear Physics ◽  
Made In

In recent years, great progress has been made in hypernuclear physics through new experimental techniques as well as theoretical development. Precision γ-ray spectroscopy of hypernuclei has revealed fine structure of various light Λ hypernuclei. Introduction of the (π-, K+) reaction has opened a possibility of studying neutron-rich Λ hypernuclei. The J-PARC facility will allow us to accelerate these experimental studies of Λ hypernuclei and extend hypernuclear physics to double strangess nuclear systems.

Development of a Lower Extremity Model for Finite Element Analysis at Blast Condition

2011 ◽  
Author(s):  
Robbin Bertucci ◽  
Jun Liao ◽  
Lakiesha Williams
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shock Waves ◽  
Lower Extremity ◽  
Direct Contact ◽  
Computational Analysis ◽  
Experimental Studies ◽  
Lower Extremities ◽  
Element Analysis ◽  
Made In

Explosions are the leading cause of death on the battlefield [1]. These explosives generate shock waves which stimulate large accelerations and deformations. The resulting loads pose serious threats to military and civilians. Since lower extremities are in direct contact with the ground, the lower extremities are commonly injured during explosions [2]. These injuries could be seriously fatal. Although experimental studies have been performed to advance these understandings [2], limited progress has been made in computational analysis of shock waves on the lower extremity.

EFFETS DE L'ACIDE ASCORBIQUE SUR PLUSIEURS VARIABLES BIOLOGIQUES NORMALEMENT AFFECTÉES PAR LE FROID

1949 ◽  
Vol 27e (6) ◽  
pp. 349-363 ◽  
Author(s):  
M. Thérien ◽  
J. Leblanc ◽  
O. Héroux ◽  
L. P. Dugal
Keyword(s):  
Blood Pressure ◽  
Ascorbic Acid ◽  
Room Temperature ◽  
Experimental Studies ◽  
The Other ◽  
Histamine Content ◽  
Exposure To Cold ◽  
Thymus Atrophy ◽  
Subsequent Administration ◽  
Made In

It has been shown recently by Dugal and Thérien that during a short or long exposure to cold, the normal hypertrophy of the adrenals is completely prevented by large doses of ascorbic acid, and that, nevertheless, at the same time, resistance is increased towards the same damaging agent. So, the most universally accepted criterion of damage caused by stress is abolished when the animals exposed to cold receive large doses of ascorbic acid. Starting from that observation, it was natural to wonder what would be the effects of the ascorbic acid on the biological changes normally associated with the hypertrophy of the adrenals during exposure to cold. The present paper describes the experimental studies made in that connection; the results obtained show that: (1) ascorbic acid (a) partly inhibits the thymus atrophy normally encountered upon exposure to any stress including cold, (b) accelerates in a very significant way the enlargement of the thyroid, (c) is responsible for an increase in weight of the spleen, whereas the control animals, on the contrary, show a decrease in weight of the same organ; (2) the histamine content of the adrenals, which increases at room temperature under the influence of ascorbic acid, is significantly decreased during exposure to cold under the influence of the same substance; (3) the activity of the adrenals, far from being inhibited by ascorbic acid is even increased if the cholesterol changes are taken as an index of that activity; (4) the initial hypotension—due to cold—found in our controls, is prevented by large doses of ascorbic acid; on the other hand, if hypertension develops after long exposure to cold, the subsequent administration of large doses of ascorbic acid restores the blood pressure to normal. Confirmation has also been obtained for the previously reported observation that ascorbic acid prevents the hypertrophy of the adrenals during exposure to cold.

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