scholarly journals Aeronautical and Aerospace Material and Structural Damages to Failures: Theoretical Concepts

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Andriy Viktorovich Goncharenko
Keyword(s):  
Optimal Solution ◽  
Good Choice ◽  
Material Behavior ◽  
Problem Solution ◽  
Theoretical Concepts ◽  
Aerospace Material ◽  
Failure State ◽  
Hybrid Function ◽  
Optional Function ◽  
Conditional Optimization

The goal of this paper is to investigate the possible directions of some specified methods for aeronautical and aerospace material and structure effectiveness modeling and optimization. Multioptionality hybrid function uncertainty conditional optimization doctrine application is supposed to be implemented for a degrading failure problem optimal solution determination. The optimal solution is assumed to deliver the maximum value to the probability of damage but not the failure state of the studied material behavior. The principal supposition is that there should be some certain objectively existing value extremized in the conditions of the hybrid optional function uncertainty. There is a scientific proof for the choice of a good maintenance optimal periodicity method that fits the customer’s needs, taking into account the effectiveness functions pertaining to the options. The described doctrine allows obtaining the objectively existing optimal values not with the help of a probabilistic but rather with a multioptimal concept. The subjective entropy maximum principle is the other paradigm concept involved in the considered problem solution, which is an equivalent for the uncertainty conditional optimization at the optimal hybrid function distribution determination. By applying simplified, however possible, models and expressions for effectiveness, plausible results are obtained and illustrated in diagrams visualizing the situation and allowing for the selection of a good choice. The ideas of the required material method choice optimization with respect to only two simple parameters, nevertheless, develop numerous particular combinations. Moreover, an increase in the number of parameters and further complication of the problem setting will not change the principle of the problem solution.

scholarly journals Family constellation as a treatment for overcoming the consequences of violence on victims

Temida ◽  
2017 ◽  
Vol 20 (2) ◽  
pp. 219-240
Author(s):  
Jasna Hrncic
Keyword(s):  
Sexual Violence ◽  
Social Relations ◽  
Physical Violence ◽  
Optimal Solution ◽  
Phenomenological Approach ◽  
Problem Solution ◽  
Theoretical Concepts ◽  
Positive Effects ◽  
Victims Of Violence ◽  
Consequences Of Violence

The subject of this paper is the implementation of family constellations by Bert Hellinger in work with clients with special emphasis on victims of physical and sexual violence. Although extremely popular in Europe and the world it has not been presented in Serbian scientific literature. As the approach has been developed in Germany as an answer to the situation where a significant part of population was a victim or perpetrator of violence during the Second World War causing suffering not only to them, but also to their offsprings, it offers a special contribution to the work with victims of violence. The aims of the paper are the presentation and analysis of the implementation of family constellations by Bert Hellinger and their effects generally in work with clients as well as with victims of physical and sexual violence. The technique of family constellations based on systemic and phenomenological approach is presented and discussed. Work is in the group, where participants form the circle and person who seeks problem resolution invites representatives - persons who are crucial for problem solution previously agreed with constellation facilitator - constellator. The constellator communicate with the representatives, encouraging them to express feelings, sensations and movement that will facilitate progress towards finding the optimal solution. The basic theoretical concepts are also analysed, including two types of conscience (individual and family), three basic principles of orders of love (principle of equal right to belong, principle of balance between giving and taking and principle of order) and three levels of the soul (individual, family and great soul). The approach to overcoming consequences of violence on victims of physical violence and incest through symbolic interconnecting with the perpetrator is analysed. When it is applied to violence the victim has an opportunity to get a more comprehensive understanding and to experience an alternative solution that could generate impulse for overcoming the violence. A frequent solution is that the perpetrator takes responsibility and expresses guilt for the deed and suffers together with the victim. That enables the victim to accept and overcome the effects of the violence. This solution is also useful in overcoming consequences of incest because it enables the victim to accept the perpetrator as a member of family. The victim could also have an insight into the role of other family members and significant others, accept it and find a better place in the family for himself/herself. This approach causes different reaction with public with its focus on reparation instead on retribution even in such a difficult issue as incest. Qualitative and quantitative evaluations have documented the positive effects of family constellations on problem solving and social relations of both active and observing participants. Further systematic researches of constellations? effects on victims of violence and comparative studies with other therapeutic approaches are needed.

Computer Aided Design of an Effective Fixture for FSW Processes of Titanium Alloys

2011 ◽  
Vol 473 ◽  
pp. 304-309
Author(s):  
Gianluca Buffa ◽  
Livan Fratini
Keyword(s):  
Titanium Alloys ◽  
Computer Aided Design ◽  
Welding Process ◽  
Optimal Solution ◽  
Fusion Welding ◽  
Material Behavior ◽  
Viscoplastic Material ◽  
3D Fem ◽  
Friction Stir ◽  
Aluminum And Magnesium Alloys

During the last years welded titanium components have been extensively applied in aeronautical and aerospace industries because of their high specific strength and corrosion resistance properties. Friction Stir Welding (FSW) is a solid state welding process, currently industrially utilized for difficult to be welded or “unweldable” aluminum and magnesium alloys, able to overcome the drawbacks of traditional fusion welding techniques. When titanium alloys are concerned, additional problems arise as the need for very high strength and high temperature resistant tools, gas shield protection and high stiffness machines. Additionally, the process is characterized by an elevated sensitivity to temperature variations, which, in turn, depends on the main operative parameters. Numerical simulation represents the optimal solution in order to perform an effective process optimization with affordable costs. In this paper, a fully 3D FEM model for the FSW process is proposed, that is thermo-mechanically coupled and with rigid-viscoplastic material behavior. Experimental clamping parts are modeled and the thermal loads are calculated at the varying of the cooling strategy. Finally, the effectiveness of the cooling systems is evaluated through experimental tests.

scholarly journals Policy Iterations Without Selection Property

10.29007/9rn9 ◽  
2018 ◽  
Author(s):  
Assale Adje
Keyword(s):  
Fixed Point ◽  
Minimization Problem ◽  
Optimal Solution ◽  
Good Choice ◽  
Selection Property ◽  
Perturbation Parameters

In this paper, we propose a modified policy iterations algorithm which does not rely on the selection property. The selection property is the key argument to make improvements during policy iterations. Indeed, a new policy is computed as an optimal solution of a minimization problem. However, in some cases, it might be difficult to prove that an optimal solution exists. To overcome this issue, the new policy is computed as a guaranteed sub-optimal solution of the minimization problem. The good choice of the perturbation parameters preserves the advantages of the original policy iterations algorithm such as the computation of a post-fixed point at each step and the convergence to a fixed point.

Unambiguous Goal Seeking Through Mathematical Modeling

2011 ◽  
pp. 892-900
Author(s):  
Giusseppi Forgionne ◽  
Stephen Russell
Keyword(s):  
Mathematical Modeling ◽  
Output Feedback ◽  
Decision Problem ◽  
Optimal Solution ◽  
Decision Makers ◽  
Problem Solution ◽  
Input And Output ◽  
Decision Variables ◽  
Important Form ◽  
Future Reference

All decision-making support systems (DMSS) provide both input and output feedback for the user. This feedback helps the user find a problem solution and captures any created knowledge for future reference. Goal seeking is an important form of DMSS feedback that guides the user toward the problem solution. Often in the decision support literature there is a concentration on providing forward-oriented decision assistance. From this perspective, the decision problem is viewed from the problem forward, towards a solution and advice is given with that orientation. In the literature, this is most often seen in “what-if” analysis. Goal seeking takes an inverted view where a preferred or optimal solution is known and the advice provided identifies values for the decision problem variables so that the optimal or preferred solution is obtained. Goal seeking approaches can be useful not only in identifying a solution, but also examining and explaining the relationships between decision variables. Unlike what-if analysis, which is forward oriented, goal seeking starts with a preferred outcome and decision makers do not have to manipulate decision variables in a recursive manner to examine different decision scenarios.

Effect of Blade Geometry and Foreign Object Kinetic Energy on Blades Damage

2010 ◽  
Author(s):  
Mickhail S. Nikhamkin ◽  
Leonid V. Voronov ◽  
Irina V. Semenova
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Leading Edge ◽  
Material Behavior ◽  
Plastic Strain Rate ◽  
Problem Solution ◽  
Foreign Object ◽  
The Impact ◽  
Blade Leading Edge

One of the main reasons of engine failure is foreign object damage (FOD) of compressor blades. Engine manufactures are constantly searching for blade endurance increasing methods. The problem solution requires investigation in the field of the structural factor effects on the blade damageability. The paper describes numerical analysis method of the damage process. Based on “the typical damage case” concept, this method can simulate typical blade damages: dents, tears, notches. The numerical analysis is performed by the finite element method (FEM). Material behavior is described with an elastic-plastic strain rate dependent model. Blade damage numerical model is thoroughly verified by the results of special experiments. To implement the experimental modeling, actual blades were damaged, a special experimental setup based on a pneumatic gun being used. The foreign object kinematic parameters before and after the impact, a blade leading edge displacements and residual deformation fields registered in the experiment are used as verification criteria for the numerical model. The blade leading edge thickness and a foreign object energy effect on the blade damageability is investigated. The research showed there are some foreign object kinetic energy critical values at which the damage mechanism and type are changed.

scholarly journals Redundant Representations in Evolutionary Computation

2003 ◽  
Vol 11 (4) ◽  
pp. 381-415 ◽  
Author(s):  
Franz Rothlauf ◽  
David E. Goldberg
Keyword(s):  
A Priori ◽  
Optimal Solution ◽  
Theoretical Models ◽  
Building Blocks ◽  
Evolutionary Search ◽  
A Priori Information ◽  
Genetic Operators ◽  
Theoretical Concepts ◽  
Redundant Representations ◽  
Priori Information

This paper discusses how the use of redundant representations influences the performance of genetic and evolutionary algorithms. Representations are redundant if the number of genotypes exceeds the number of phenotypes. A distinction is made between synonymously and non-synonymously redundant representations. Representations are synonymously redundant if the genotypes that represent the same phenotype are very similar to each other. Non-synonymously redundant representations do not allow genetic operators to work properly and result in a lower performance of evolutionary search. When using synonymously redundant representations, the performance of selectorecombinative genetic algorithms (GAs) depends on the modification of the initial supply. We have developed theoretical models for synonymously redundant representations that show the necessary population size to solve a problem and the number of generations goes with O(2kr/r), where kr is the order of redundancy and r is the number of genotypic building blocks (BB) that represent the optimal phenotypic BB. As a result, uniformly redundant representations do not change the behavior of GAs. Only by increasing r, which means overrepresenting the optimal solution, does GA performance increase. Therefore, non-uniformly redundant representations can only be used advantageously if a-priori information exists regarding the optimal solution. The validity of the proposed theoretical concepts is illustrated for the binary trivial voting mapping and the real-valued link-biased encoding. Our empirical investigations show that the developed population sizing and time to convergence models allow an accurate prediction of the empirical results.

scholarly journals The User-Preferred Optimal Flight Parameters in an Active Navigational System in a Multi-Alternative Situation

2020 ◽  
Vol 2020 (2) ◽  
pp. 1-12
Author(s):  
Andriy Viktorovich Goncharenko
Keyword(s):  
Control System ◽  
Good Choice ◽  
Problem Solution ◽  
Aircraft Control ◽  
Active System ◽  
Managerial Decision ◽  
Subjective Analysis ◽  
Navigational System ◽  
And Control ◽  
Aircraft Control System

AbstractThe goal of this paper is to investigate the influence of the objectively existing effectiveness functions of an aircraft control system upon the control and managerial decision making process in the framework of the subjective entropy maximum princi-ple. The subjective analysis theory entropy paradigm makes it possible to consider the aircraft control system based upon personal preferences as an active system governed by an individual (active element of the control system) with the help of her/his individual subjective preferences optimal distributions obtained in conditions of operational multi-alternativeness and those operational alternatives the active system active element’s individual subjective preferences uncertainty. The described ap-proach takes into account the simple two-alternative operational situation in regards with the objectively existing effectiveness functions, related to the aircraft control system, in the view of a controlled parameter and a combination of it with its rate as the ratio. The obtained expressions for the objective functional extremal functions of the effectiveness and preferences, as well as the subjective entropy of the alternatives preferences, illustrated in diagrams visualize the situation and allow taking a good choice. The ideas of the required proper governing, managing, and control methods choice optimization with respect to only 2 alternative objective effectiveness functions arguments might be simple; nevertheless, increasing the number of parameters and further complication of the problem setting will not change the principle of the problem solution.

scholarly journals Benefit of Unsaturated Soil Mechanics Approach on the Modeling of Early-Age Behavior of Rammed Earth Building

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 362
Author(s):  
Parul Chauhan ◽  
Noémie Prime ◽  
Olivier Plé
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Material Behavior ◽  
Rammed Earth ◽  
Safety Criterion ◽  
Practical Guide ◽  
Earth Construction ◽  
Failure State ◽  
Unsaturated Soil Mechanics

Rammed earth has the potential to reduce the carbon footprint and limit the energy consumption in the building sector due to its sustainable characteristics. Still, its use is not generalized due to a lack of understanding of the material behavior, notably its sensitivity to water. The coupled hydro-mechanical behavior has been recently studied in the framework of unsaturated soil mechanics, using suction as the parameter to represent the hydric state. This dependency of the mechanical behavior on the hydric state leads to uncertainty of the drying period required to progress in the construction process. Notably, the drying period before building the next floor is unknown. To determine the drying period, thermo-hydro-mechanical coupled finite element method simulations were carried out on a single wall by using the unsaturated soil mechanics approach and safety criterion recommendations from the practical guide for rammed earth construction in France. It was determined that it takes significant time for the construction of additional floor both in ‘summer-like’ and ‘winter-like’ environmental conditions, whereas the walls were far away from the ultimate failure state. Thus the drying periods were overestimated. It was concluded that the safety criterion from the practical guide is very conservative and drying periods can be reduced without significantly compromising the safety factor.

scholarly journals An Improved Hybrid Genetic Algorithm with a New Local Search Procedure

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Wen Wan ◽  
Jeffrey B. Birch
Keyword(s):  
Genetic Algorithm ◽  
Local Search ◽  
Hybrid Genetic Algorithm ◽  
Optimal Solution ◽  
Global Optimum ◽  
Good Choice ◽  
Fine Tuning ◽  
Learning Procedure ◽  
Local Search Procedure ◽  
Important Challenge

One important challenge of a hybrid genetic algorithm (HGA) (also called memetic algorithm) is the tradeoff between global and local searching (LS) as it is the case that the cost of an LS can be rather high. This paper proposes a novel, simplified, and efficient HGA with a new individual learning procedure that performs a LS only when the best offspring (solution) in the offspring population is also the best in the current parent population. Additionally, a new LS method is developed based on a three-directional search (TD), which is derivative-free and self-adaptive. The new HGA with two different LS methods (the TD and Neld-Mead simplex) is compared with a traditional HGA. Four benchmark functions are employed to illustrate the improvement of the proposed method with the new learning procedure. The results show that the new HGA greatly reduces the number of function evaluations and converges much faster to the global optimum than a traditional HGA. The TD local search method is a good choice in helping to locate a global “mountain” (or “valley”) but may not perform the Nelder-Mead method in the final fine tuning toward the optimal solution.

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