scholarly journals Reliability-Based Topology Optimization Using Two Alternative Inverse Optimum Safety Factor Approaches: Application to Bridge Structures

2020 ◽  
Vol 30 (3) ◽  
pp. 498-511
Author(s):  
Ghias Kharmanda ◽  
Imad R. Antypas ◽  
Alexey G. Dyachenko
Keyword(s):  
Topology Optimization ◽  
Safety Factor ◽  
Optimization Model ◽  
High Performance ◽  
Bridge Structure ◽  
Objective Performance ◽  
Bridge Structures ◽  
Alternative Approaches ◽  
Alternative Choice

Introduction. The Deterministic Topology Optimization model provides a single solution for a given design space, while the Reliability-Based Topology Optimization model provides several reliability-based topology layouts with high-performance levels. The objective of this work is to develop two strategies that can provide the designer with two categories of resulting topologies. Materials and Methods. Two alternative approaches based on the Inverse Optimum Safety Factor are developed: the first one is called the Objective-Based IOSF Approach and the second one is called Performance-Based IOSF Approach. When dealing with bridge structures, the uncertainty on the input parameters (boundary conditions, material properties, geometry, etc.) and also output parameters (compliance, etc.) should not be ignored. The sensitivity analysis is the fundamental idea of both developed approaches, identifies the role of each parameter on the structural performance. In addition, the optimization domain choice is important when eliminating material that should not affect the structure functioning. Results. Two numerical examples on a 2D bridge structure are presented to demonstrate the efficiency of the developed approaches. When considering a certain reliability level, the Reliability-Based Topology Optimization leads to two different configurations relative to the Deterministic Topology Optimization one. When increasing the reliability levels, the quantity of materials decreases that leads to an increase in the number of holes in the structures. Discussion and Conclusion. In addition to their simplified implementation, the developed alternative approaches can be considered as two generative tools to produce two different categories (families) of solutions where an alternative choice between two functions (objective/performance) is presented.

scholarly journals Inverse Optimum Safety Factor Method for Reliability-Based Topology Optimization Applied to Free Vibrated Structures

2019 ◽  
pp. 8-19 ◽  
Author(s):  
Ghias Kharmanda ◽  
Imad R. Antypas ◽  
Alexey G. Dyachenko
Keyword(s):  
Topology Optimization ◽  
Structure Function ◽  
Modal Analysis ◽  
Safety Factor ◽  
Optimization Model ◽  
High Performance ◽  
Structural Type ◽  
Efficient Tool ◽  
Performance Levels ◽  
Reliability Level

Introduction. The classical topology optimization leads to a prediction of the structural type and overall layout, and gives a rough description of the shape of the outer as well as inner boundaries of the structure. However, the probabilistic topology optimization (or reliability-based topology optimization) model leads to several reliability-based topologies with high performance levels. The objective of this work is to provide an efficient tool to integrate the reliability-based topology optimization model into free vibrated structure. Materials and Methods. The developed tool is called inverse optimum safety method. When dealing with modal analysis, the choice of optimization domain is highly important in order to be able to eliminate material taking account of the constraints of fabrication and without affecting the structure function. This way the randomness can be applied on certain boundary parameters. Results. Numerical applications on free vibrated structures are presented to show the efficiency of the developed strategy. When considering a required reliability level, the resulting topology represents a different topology relative to the deterministic resulting one. Discussion and Conclusion. In addition to its simplified implementation, the developed inverse optimum safety factor strategy can be considered as a generative tool to provide the designer with several solutions for free vibrated structures with different performance levels.

scholarly journals Linear versus nonlinear reliability-based topology optimization with application to bridge structures

2021 ◽  
Vol 273 ◽  
pp. 04009
Author(s):  
Ghais Kharmanda ◽  
Hasan Mulki ◽  
Antypas Imad
Keyword(s):  
Topology Optimization ◽  
Lognormal Distribution ◽  
Design Space ◽  
Bridge Structure ◽  
Distribution Law ◽  
Numerical Application ◽  
Linear Distribution ◽  
Bridge Structures ◽  
Distribution Laws ◽  
Nonlinear Normal

In general, two types of topology optimization models can be found in literature. The first type is called Deterministic Topology Optimization (DTO) leading to a single layout when considering a given design space. The second type is called Reliability-Based Topology Optimization (RBTO) leading to various solutions. In our previous work, two strategies based on the Inverse Optimum Safety Factors (IOSF) were established and applied simply to the normal (Gaussian or linear) distribution law. In this work, linear and nonlinear (normal and lognormal) distribution RBTO cases are compared. A bridge structure is considered a numerical application to perform this comparison where different layouts at the same level of reliability can be found. The numerical results show that regarding the distribution laws, certain output parameters and safety factor values are affected. This change can affect the resulting topology layouts as well as the output parameter such as the compliance. When rising the values of the reliability index, the values of the compliance become larger and the volume values become lesser for the lognormal distribution when comparing to the normal one.

scholarly journals Integration of reliability-based topology optimization into biomechanics: Application on hollow stems used in cementless total hip arthroplasty

2020 ◽  
Vol 210 ◽  
pp. 06003
Author(s):  
Ghais Kharmanda ◽  
Imad Antypas ◽  
Alexey Dyachenko
Keyword(s):  
Topology Optimization ◽  
Hip Replacement ◽  
High Performance ◽  
Design Space ◽  
Design Stage ◽  
Manufacturing Constraints ◽  
Element Discretization ◽  
Performance Levels ◽  
Total Hip ◽  
Alternative Approaches

The integration of topology optimization into biomechanical applications possesses an important key to increase the performance levels. In literature, two models can be found: Deterministic Topology Optimization (DTO) and Reliability-Based Topology Optimization (RBTO). The DTO leads to a single layout for a given design space. However, the RBTO generates several reliability-based topologies with high performance levels. Topology optimization has been already integrated into biomechanical applications such as prosthesis design. The filter-based approaches being tied to the element discretization, are previously used to control the resulting topologies or to prevent undesirable designs. These are expensive operations for fine meshes or complex domains and numerous numerical difficulties can be met. In this work, the RBTO is integrated at the conceptual design stage of the total hip replacement to control the resulting topologies to meet different constraints such as manufacturing constraints. This can provide several types of hollow stems considering the daily loading cases. Two alternative approaches based on the Optimum Safety Factors (OSF) are developed to provide two categories of solutions. The RBTO model can be integrated into the additive manufacturing technology as a topology generator satisfying several manufacturing constraints. The resulting different configurations can then be provided for various patients.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

Two Short Tests Fail to Detect Vigilance Decrements

2001 ◽  
Vol 17 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Juan Botella ◽  
María José Contreras ◽  
Pei-Chun Shih ◽  
Víctor Rubio
Keyword(s):  
Individual Differences ◽  
High Performance ◽  
Selection Process ◽  
Vigilance Task ◽  
Air Traffic Controllers ◽  
Job Selection ◽  
Performance Deterioration ◽  
Short Test ◽  
Psychological Dimensions

Summary: Deterioration in performance associated with decreased ability to sustain attention may be found in long and tedious task sessions. The necessity for assessing a number of psychological dimensions in a single session often demands “short” tests capable of assessing individual differences in abilities such as vigilance and maintenance of high performance levels. In the present paper two tasks were selected as candidates for playing this role, the Abbreviated Vigilance Task (AVT) by Temple, Warm, Dember, LaGrange and Matthews (1996) and the Continuous Attention Test (CAT) by Tiplady (1992) . However, when applied to a sample of 829 candidates in a job-selection process for air-traffic controllers, neither of them showed discriminative capacity. In a second study, an extended version of the CAT was applied to a similar sample of 667 subjects, but also proved incapable of properly detecting individual differences. In short, at least in a selection context such as that studied here, neither of the tasks appeared appropriate for playing the role of a “short” test for discriminating individual differences in performance deterioration in sustained attention.

scholarly journals Review of annual progress of bridge engineering in 2019

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Renda Zhao ◽  
Yuan Yuan ◽  
Xing Wei ◽  
Ruili Shen ◽  
Kaifeng Zheng ◽  
...  
Keyword(s):  
High Performance ◽  
Concrete Bridges ◽  
Bridge Engineering ◽  
Research Progress ◽  
Steel Bridge ◽  
Wind Resistance ◽  
Main Research ◽  
Bridge Model ◽  
Bridge Evaluation ◽  
Bridge Structures

AbstractBridge construction is one of the cores of traffic infrastructure construction. To better develop relevant bridge science, this paper introduces the main research progress in China and abroad in 2019 from 13 aspects, including concrete bridges and the high-performance materials, the latest research on steel-concrete composite girders, advances in box girder and cable-supported bridge analysis theories, advance in steel bridges, the theory of bridge evaluation and reinforcement, bridge model tests and new testing techniques, steel bridge fatigue, wind resistance of bridges, vehicle-bridge interactions, progress in seismic design of bridges, bridge hydrodynamics, bridge informatization and intelligent bridge and prefabricated concrete bridge structures.

scholarly journals Functional response of Harmonia axyridis preying on Acyrthosiphon pisum nymphs: the effect of temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yasir Islam ◽  
Farhan Mahmood Shah ◽  
Xu Rubing ◽  
Muhammad Razaq ◽  
Miao Yabo ◽  
...  
Keyword(s):  
Functional Response ◽  
High Performance ◽  
Acyrthosiphon Pisum ◽  
Harmonia Axyridis ◽  
Effect Of Temperature ◽  
Functional Responses ◽  
Aphid Control ◽  
Host Aphid ◽  
Predator Foraging

AbstractIn the current study, we investigated the functional response of Harmonia axyridis adults and larvae foraging on Acyrthosiphon pisum nymphs at temperatures between 15 and 35 °C. Logistic regression and Roger’s random predator models were employed to determine the type and parameters of the functional response. Harmonia axyridis larvae and adults exhibited Type II functional responses to A. pisum, and warming increased both the predation activity and host aphid control mortality. Female and 4th instar H. axyridis consumed the most aphids. For fourth instar larvae and female H. axyridis adults, the successful attack rates were 0.23 ± 0.014 h−1 and 0.25 ± 0.015 h−1; the handling times were 0.13 ± 0.005 h and 0.16 ± 0.004 h; and the estimated maximum predation rates were 181.28 ± 14.54 and 153.85 ± 4.06, respectively. These findings accentuate the high performance of 4th instar and female H. axyridis and the role of temperature in their efficiency. Further, we discussed such temperature-driven shifts in predation and prey mortality concerning prey-predator foraging interactions towards biological control.

Revealing the role of dopants in mitigating degradation phenomena in sodium-ion layered cathodes

2021 ◽  
Vol 23 (3) ◽  
pp. 2038-2045
Author(s):  
Kyoungmin Min ◽  
Young-Han Shin
Keyword(s):  
Cathode Materials ◽  
High Performance ◽  
High Stability ◽  
Sodium Ion ◽  
Sodium Ion Batteries ◽  
Layered Cathode Materials ◽  
Layered Cathodes

Prevention of the degradation of sodium-based layered cathode materials is the key to developing high-performance and high-stability sodium-ion batteries.

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