scholarly journals Graph based discrete optimization in structural dynamics

2014 ◽  
Vol 62 (1) ◽  
pp. 91-102
Author(s):  
B. Blachowski ◽  
W. Gutkowski
Keyword(s):  
Structural Optimization ◽  
Minimum Weight ◽  
Continuous Optimization ◽  
Graph Representation ◽  
Wind Loading ◽  
Transmission Tower ◽  
Simple Method ◽  
Deterministic Dynamic ◽  
Starting Point ◽  
Discrete Values

Abstract In this study, a relatively simple method of discrete structural optimization with dynamic loads is presented. It is based on a tree graph, representing discrete values of the structural weight. In practical design, the number of such values may be very large. This is because they are equal to the combination numbers, arising from numbers of structural members and prefabricated elements. The starting point of the method is the weight obtained from continuous optimization, which is assumed to be the lower bound of all possible discrete weights. Applying the graph, it is possible to find a set of weights close to the continuous solution. The smallest of these values, fulfilling constraints, is assumed to be the discrete minimum weight solution. Constraints can be imposed on stresses, displacements and accelerations. The short outline of the method is presented in Sec. 2. The idea of discrete structural optimization by means of graphs. The knowledge needed to apply the method is limited to the FEM and graph representation. The paper is illustrated with two examples. The first one deals with a transmission tower subjected to stochastic wind loading. The second one with a composite floor subjected to deterministic dynamic forces, coming from the synchronized crowd activities, like dance or aerobic.

ANN-Based Structure Optimization with Fatigue Reliability Constrains

2012 ◽  
Vol 204-208 ◽  
pp. 3128-3131
Author(s):  
Li Rong Sha ◽  
Yue Yang
Keyword(s):  
Structural Optimization ◽  
Objective Function ◽  
Reliability Analysis ◽  
Response Surface ◽  
Minimum Weight ◽  
Structure Optimization ◽  
Fatigue Reliability ◽  
Ann Model ◽  
Surface Method ◽  
The Relationship

The ANN-based optimization for considering fatigue reliability requirements in structural optimization was proposed. The ANN-based response surface method was employed for performing fatigue reliability analysis. The fatigue reliability requirements were considered as constraints while the weight as the objective function, the ANN model was adopted to establish the relationship between the fatigue reliability and geometry dimension of the structure, the optimal results of the structure with a minimum weight was reached.

Beyond the heuristic approach to Kolmogorov-Smirnov theorems

1982 ◽  
Vol 19 (A) ◽  
pp. 359-365 ◽  
Author(s):  
David Pollard
Keyword(s):  
Weak Convergence ◽  
Goodness Of Fit ◽  
Empirical Distribution ◽  
Distribution Functions ◽  
Heuristic Approach ◽  
Convergence Theory ◽  
Simple Method ◽  
Starting Point ◽  
Kolmogorov Smirnov ◽  
The Subject

The theory of weak convergence has developed into an extensive and useful, but technical, subject. One of its most important applications is in the study of empirical distribution functions: the explication of the asymptotic behavior of the Kolmogorov goodness-of-fit statistic is one of its greatest successes. In this article a simple method for understanding this aspect of the subject is sketched. The starting point is Doob's heuristic approach to the Kolmogorov-Smirnov theorems, and the rigorous justification of that approach offered by Donsker. The ideas can be carried over to other applications of weak convergence theory.

Solar UAV design framework for a HALE flight

2019 ◽  
Vol 91 (7) ◽  
pp. 927-937
Author(s):  
Hoyon Hwang ◽  
Jaeyoung Cha ◽  
Jon Ahn
Keyword(s):  
User Interfaces ◽  
Minimum Weight ◽  
Lift Coefficient ◽  
Aircraft Design ◽  
Design Framework ◽  
Night Time ◽  
Simple Method ◽  
Content Type ◽  
Aerial Vehicle ◽  
Long Endurance

Purpose The purpose of this paper is to present the development of an optimal design framework for high altitude long endurance solar unmanned aerial vehicle. The proposed solar aircraft design framework provides a simple method to design solar aircraft for users of all levels of experience. Design/methodology/approach This design framework consists of algorithms and user interfaces for the design of experiments, optimization and mission analysis that includes aerodynamics, performance, solar energy, weight and flight distances. Findings The proposed sizing method produces the optimal solar aircraft that yields the minimum weight and satisfies the constraints such as the power balance, the night time energy balance and the lift coefficient limit. Research limitations/implications The design conditions for the sizing process are given in terms of mission altitudes, flight dates, flight latitudes/longitudes and design factors for the aircraft configuration. Practical implications The framework environment is light and easily accessible as it is implemented using open programs without the use of any expensive commercial tools or in-house programs. In addition, this study presents a sizing method for solar aircraft as traditional sizing methods fail to reflect their unique features. Social implications Solar aircraft can be used in place of a satellite and introduce many advantages. The solar aircraft is much cheaper than the conventional satellite, which costs approximately $200-300m. It operates at a closer altitude to the ground and allows for a better visual inspection. It also provides greater flexibility of missions and covers a wider range of applications. Originality/value This study presents the implementation of a function that yields optimized flight performance under the given mission conditions, such as climb, cruise and descent for a solar aircraft.

Damage Inspection and Assessment on a Transmission Angle Tower in Coastal Areas

2013 ◽  
Vol 671-674 ◽  
pp. 650-654
Author(s):  
Peng Yun Li ◽  
Bo Chen ◽  
Yu Zhou Sun
Keyword(s):  
Structural Model ◽  
Wind Loading ◽  
Transmission Tower ◽  
Line System ◽  
Steel Material ◽  
Transmission Angle ◽  
Commercial Package ◽  
Loading Effects ◽  
Structural Responses ◽  
Element Approach

The field inspection and safety assessment of a transmission angle tower are actively carried out in this study. The field measurement and inspection are firstly introduced and then the structural model is constructed based on finite element approach with the aiding of commercial package ANSYS. The equation of motion of the transmission tower-line system is established for numerical analysis. The gravity, base settlement and dynamic wind loading are applied on the tower to examine the structural responses. The deformation and stresses distribution of the transmission angle tower are computed to explore the damage reasons. The made observations indicate that the peak stresses of some members are large than the permitted yielding stresses of steel material. The damage event is induced by coupling loading effects

Simultaneous detection of Dopamine and Serotonin in real complex matrices

2020 ◽  
Vol 16 ◽  
Author(s):  
Florina Truţă ◽  
Mihaela Tertisa ◽  
Cecilia Cristea ◽  
Florin Graur
Keyword(s):  
Carbon Nanotubes ◽  
Gold Nanoparticles ◽  
Simultaneous Detection ◽  
Multiwall Carbon Nanotubes ◽  
Differential Pulse ◽  
Sensitive Detection ◽  
Complex Matrices ◽  
Simple Method ◽  
Starting Point ◽  
Highly Sensitive Detection

Background: Neurotransmitters are chemical messengers with crucial implication in human body. Perturbations in concentration of neurotransmitters can affect a multitude of mental and physical functions, such as heart rate, sleep, appetite and mood. Thus, the sensitive detection of these compounds is a real need for a new generation of treatments. Method: Two important neurotransmitters namely dopamine and serotonin were investigated in this study for simultaneous detection using differential pulse voltammetry. The optimization of several surface parameters were performed in order to choose the best electrode material for electrochemical oxidation of targets. Screen printed electrodes based on carbon, gold and platinum and modified with different nanomaterials (carbon nanotubes, gold nanoparticles and carbon nanotubes decorated with gold nanoparticles) were tested. Results: Carbon-based electrodes modified with multiwall carbon nanotubes and gold nanoparticles were chosen after the optimization protocol. Linear correlations between the analytic signals obtained and the concentration of dopamine and serotonin respectively were obtained with good sensitivity and the detection limits were 0.3 µM for dopamine and 0.8 µM for serotonin with no significant reciprocal influences. Selectivity studies were also performed, as well as tests in real samples (e.g. human serum, tears and saliva) complex matrices for which acceptable recoveries were obtained. Conclusion: The results obtained within this study can be considered as an important starting point for the development of a fast and simple method for selective and highly sensitive detection of neurotransmitters, with possible applications in the diagnosis of different pathologies and for monitoring the effectiveness of the applied drug treatment.

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