scholarly journals AN ANALYSIS OF SCALING METHODS FOR STRUCTURAL COMPONENTS IN THE CONTEXT OF SIZE EFFECTS AND NONLINEAR PHENOMENA

2020 ◽  
Vol 1 ◽  
pp. 797-806
Author(s):  
O. Altun ◽  
P. Wolniak ◽  
I. Mozgova ◽  
R. Lachmayer
Keyword(s):  
Size Effects ◽  
Scale Model ◽  
Nonlinear Phenomena ◽  
Component Size ◽  
Scaling Methods ◽  
System Properties ◽  
The Impact ◽  
Reduced Scale ◽  
Selection Of ◽  
Similitude Theory

AbstractSimilitude theory helps engineers to investigate system properties and behaviour with scaling methods. The application of such methods reduces the time for product development and production of prototypes. With increasing component size, the impact of size effects and nonlinear phenomena becomes more important in reduced scale model testing. The aim of this paper is to provide an overview of the scaling methods and their applicability with regard to size effects and nonlinear phenomena as well as a procedure to support the selection of a suitable method for the scaling task of structures.

Experimental Program of Indoor Model Research about Single Pile Negative Friction

2014 ◽  
Vol 501-504 ◽  
pp. 160-165
Author(s):  
Chang Liu Chen ◽  
Song Qi Wei ◽  
Shuai Hua Ye ◽  
Yan Liu
Keyword(s):  
Skin Friction ◽  
Pile Foundation ◽  
Scale Model ◽  
Experimental Program ◽  
Engineering Practice ◽  
Negative Skin Friction ◽  
Friction Resistance ◽  
Model Research ◽  
Reduced Scale ◽  
Selection Of

This article aims to study the influence of negative skin friction resistance of waterishlogged pile foundation, through indoor scale model test of pile foundation in the loess areas. The program involved in the model similar than design, the model groove design, the selection of test materials, the design of the ground soil, the layout of measuring points and the research of load method in the test. Through the experimental study on the reduced scale model, we can deepen the understanding of the action mechanism of negative skin friction resistance of the pile, which could guide the engineering practice and design.

Hot Radial Upset-Extruding Process for Tube Structure with a Nozzle of 316LN Stainless Steel

2014 ◽  
Vol 1004-1005 ◽  
pp. 1245-1255
Author(s):  
Xin Wang ◽  
Xiao Feng ◽  
Lei Zhang ◽  
Feng Lin ◽  
Ji Luan Pan
Keyword(s):  
Metal Flow ◽  
Scale Model ◽  
Pure Lead ◽  
Main Pipe ◽  
Tube Billet ◽  
Plastic Forming ◽  
Radial Outflow ◽  
The Impact ◽  
Reduced Scale ◽  
Tube Structure

AP1000 nuclear power main pipe, a type of complicated thick-walled tube structure with both high and thick-walled nozzles, is one of the key parts in nuclear island. It is required to be manufactured by integral plastic forming technique. Up to now, no economical and efficient plastic forming process for AP1000 main pipe has been reported. To aim for forming the tube structure with a nozzle such as AP1000 main pipe, a radial upset-extruding (RUE) process was developed, in which the initial billet is an extruded tube with a hole. RUE process is an extrusion method which realizes radial outflow of the metal around the hole of tube billet through an axial upsetting force and restriction of dies. Thick-walled tube structure with a nozzle derived from AP1000 main pipe was simplified to be a thick-walled three-way pipe, on which RUE process was analyzed based. Combined with reduced scale model experiments, thermomechanical coupled finite element analysis integrated with recrystallization models of 316LN was performed to investigate RUE process. Metal flow, deformation distribution, recrystallization distribution, and extrusion load and clamping load in RUE process was analyzed. The experimental workpiece of pure lead based on reduced scale model validate metal flow behavior predicted by using numerical simulation. The results indicate that the essence of RUE process is to deflect the flow of the material around the orifice of the tube billet. The loads of dies are significantly sensitive to the initial forming temperature and the friction coefficient, while the impact of the extrusion velocity is negligible. RUE process could be used to form thick-walled tube structure with a nozzle, and it has a potential for solving the manufacture of AP1000 main pipe.

Reduced-Scale Model Design for a High-Speed Rotor System Based on Similitude Theory

2019 ◽  
Author(s):  
Biao Zhou ◽  
Haotian Liang ◽  
Hui Miao ◽  
Chaoping Zang
Keyword(s):  
High Speed ◽  
Structural Engineering ◽  
Rotor System ◽  
Scale Model ◽  
Mode Shapes ◽  
Design Parameters ◽  
Critical Speeds ◽  
Operation Speed ◽  
Reduced Scale ◽  
Similitude Theory

Abstract Reduced-scale models are often established based on similitude theory as an alternative to the direct experimental observation on the prototype, which is usually oversized or requires unacceptable expenses. Much insight into the similitude theory applied to various fields in structural engineering, vibration and impact problems has been gained to date. However, the efficient dynamic similarity design of complex rotors remains elusive. This paper is devoted to developing a reduced-scale model based on similitude theory from a high-speed rotor system prototype. Three critical speeds within the range of operating speeds characterize this flexible rotor. A reduced scaling design strategy for the complex rotor system is proposed as a two-step scheme. Similarity conditions relating the critical design parameters (such as rotor geometry, support stiffness, etc.) between the reduced-scale model and the prototype are derived. The scaling factors are accordingly determined by a dimensional analysis in combination with the governing equation of rotordynamics. This leads to a downsized rotor model with distorted geometric configuration whose operation speed is efficiently narrowed down. Dynamic similitude is assured by proportionally scaling down the three critical speeds while the rotor mode shapes still maintain high correlation between the prototype and downscaled model. The resultant reduced-scale model of the rotor system will practically guide the construction of the essential part of a whole engine dynamics test rig for laboratory use.

Research of Indoor Reduced Scale Model Test for Negative Friction of Pile Group

2014 ◽  
Vol 501-504 ◽  
pp. 155-159
Author(s):  
Chang Liu Chen ◽  
Yan Liu ◽  
Shuai Hua Ye ◽  
Song Qi Wei
Keyword(s):  
Model Test ◽  
Pile Group ◽  
Scale Model ◽  
Measuring Point ◽  
Loess Area ◽  
Similarity Ratio ◽  
Negative Friction ◽  
Design And Practice ◽  
Reduced Scale ◽  
Selection Of

The target of this paper is to research the change law of the negative friction for after soaking. The negative friction of pile group is measured through the indoor reduced scale model test in loess area. The similarity ratio design, the groove design of the model, the selection of test materials, the design of the ground soil, the layout of measuring point and the research of load method are involved in this test. Through the study on the reduced scale model, it will have a deeper understanding to the mechanism of pile side negative frictional resistance.It also can guide the design and practice of other engineering.

scholarly journals Uplift Bearing Capacity of Cone-Cylinder Foundation for Transmission Line in Frozen Soil Regions, Using Reduced-Scale Model Tests and Numerical Simulations

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2066
Author(s):  
Yangchun Han ◽  
Jiulong Cheng ◽  
Qiang Cui ◽  
Qianyun Dong ◽  
Wanting Song
Keyword(s):  
Transmission Line ◽  
Numerical Simulations ◽  
Bearing Capacity ◽  
Frozen Soil ◽  
Scale Model ◽  
Three Dimension ◽  
Scale Modeling ◽  
Bottom Width ◽  
The Impact ◽  
Reduced Scale

In order to analyze the uplift bearing capacity of cone-cylinder foundation for transmission line in frozen soil regions, a series of reduced-scale modeling tests and numerical simulations are carried out. First, three reduced-scale cone-cylinder foundations with the same sizes, that are five times smaller than the prototype, are made and then loaded under uplift load at −5 °C, −10 °C, and −15 °C, respectively. On this basis, the foundations of nine sizes are modeled and loaded by numerical simulation. The impact of three dimension factors, including the ratio of depth to bottom width ( λ = h t / D t ), the top diameter of the cone-cylinder (d), and the bottom diameter of the cone-cylinder (D), on the uplift bearing capacity of foundations have been investigated. The results reveal that, for cone-cylinder foundation, the uplift bearing capacity is obviously affected by the freezing temperatures and the foundation sizes. The capacity is negatively correlated with the former. Whereas the order of correlation with the latter is as follows: λ, D, and d based on the comprehensive results of range and variance analysis, but none of them are the significant factors, according to the F-test. Furthermore, three failure mechanisms of frozen soil are distinguished and named T-mode, V-mode, and U-mode, respectively. Based on the above results, the bearing mechanism of cone-cylinder foundation in frozen soil is elaborated in detail.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

Structural Analysis for a Reduced Scale Model of a Hydropower Plant Debris Containment Grid

2017 ◽  
Author(s):  
Felipe Santos de Castro ◽  
Eduardo Tadashi Katsuno ◽  
Andre Mitsuo Kogishi ◽  
José Marcos Paz de Souza ◽  
Joao Lucas Dozzi Dantas Dantas
Keyword(s):  
Structural Analysis ◽  
Hydropower Plant ◽  
Scale Model ◽  
Plant Debris ◽  
Reduced Scale

Impact of removing ESBL designation from culture reports on the selection of antibiotics for the treatment of infections associated with ESBL-producing organisms

2020 ◽  
Vol 41 (5) ◽  
pp. 604-607 ◽  
Author(s):  
Mark D. Lesher ◽  
Cory M. Hale ◽  
Dona S. S. Wijetunge ◽  
Matt R. England ◽  
Debra S. Myers ◽  
...  
Keyword(s):  
Antimicrobial Stewardship ◽  
Antibiotic Prescribing ◽  
The Impact ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor ◽  
Selection Of

AbstractWe characterized the impact of removal of the ESBL designation from microbiology reports on inpatient antibiotic prescribing. Definitive prescribing of carbapenems decreased from 48.4% to 16.1% (P = .01) and β-lactam–β-lactamase inhibitor combination increased from 19.4% to 61.3% (P = .002). Our findings confirm the importance of collaboration between microbiology and antimicrobial stewardship programs.

scholarly journals The Impact of Alkaloid-Producing Epichloë Endophyte on Forage Ryegrass Breeding: A New Zealand Perspective

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 158
Author(s):  
Colin Eady
Keyword(s):  
Seed Production ◽  
Health Issues ◽  
Abiotic Stressors ◽  
Livestock Health ◽  
The Right ◽  
The Impact ◽  
The Relationship ◽  
And Storage ◽  
Selection Of ◽  
Epichloë Endophyte

For 30 years, forage ryegrass breeding has known that the germplasm may contain a maternally inherited symbiotic Epichloë endophyte. These endophytes produce a suite of secondary alkaloid compounds, dependent upon strain. Many produce ergot and other alkaloids, which are associated with both insect deterrence and livestock health issues. The levels of alkaloids and other endophyte characteristics are influenced by strain, host germplasm, and environmental conditions. Some strains in the right host germplasm can confer an advantage over biotic and abiotic stressors, thus acting as a maternally inherited desirable ‘trait’. Through seed production, these mutualistic endophytes do not transmit into 100% of the crop seed and are less vigorous than the grass seed itself. This causes stability and longevity issues for seed production and storage should the ‘trait’ be desired in the germplasm. This makes understanding the precise nature of the relationship vitally important to the plant breeder. These Epichloë endophytes cannot be ‘bred’ in the conventional sense, as they are asexual. Instead, the breeder may modulate endophyte characteristics through selection of host germplasm, a sort of breeding by proxy. This article explores, from a forage seed company perspective, the issues that endophyte characteristics and breeding them by proxy have on ryegrass breeding, and outlines the methods used to assess the ‘trait’, and the application of these through the breeding, production, and deployment processes. Finally, this article investigates opportunities for enhancing the utilisation of alkaloid-producing endophytes within pastures, with a focus on balancing alkaloid levels to further enhance pest deterrence and improving livestock outcomes.

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