Optimal design of tapered composite structures with a dynamic boundary subset blending model

2021 ◽  
pp. 095441002198912
Author(s):  
Zijian Zhang ◽  
Xiaoping Ma ◽  
Peng Jin
Keyword(s):  
Genetic Algorithm ◽  
Optimal Design ◽  
Composite Structures ◽  
Upper Bounds ◽  
Stacking Sequence ◽  
Lower And Upper Bounds ◽  
Dynamic Boundary ◽  
Boundary Subset ◽  
Configuration Problem

Based on the classical bending rule that the plies composing the thinner region should be a subset of the ones of the thicker region for two adjacent laminates, a genetic algorithm–based dynamic boundary subset blending model is proposed to optimize the global stacking sequence of composite structures with ply-drops. Besides the stacking sequence chromosome of the guide laminate and ply number chromosome of each panel, a chromosome of a dynamic boundary subset factor is introduced for each panel to obtain a fully blended design. The lower and upper bounds of the dynamic boundary subset factor chromosome for each panel is determined by the ply number chromosomes of the panel and its adjacent panels. The stacking sequence of each panel can be determined by selection from combinations of various stacking sequences. The proposed blending model can solve the problem that laminates with identical thicknesses have the completely same layups even when they are not adjacent to each other. The optimal feasible designs outperform other published solutions for the 18-panel horseshoe configuration problem based on the classical bending rule.

Simple Bounds and Monotnicity the Call Congestion of Finite Multiserver Delay Systems

1988 ◽  
Vol 2 (1) ◽  
pp. 129-138 ◽  
Author(s):  
Nico M van Dijk ◽  
Pantelis Tsoucas ◽  
Jean Walrand
Keyword(s):  
Optimal Design ◽  
Sample Path ◽  
Upper Bounds ◽  
Monotonicity Property ◽  
Delay Systems ◽  
Asymptotic Result ◽  
Lower And Upper Bounds ◽  
Waiting Room ◽  
Numerical Evidence ◽  
Simple Bounds

Simple and insensitive lower and upper bounds are proposed for the call congestion of M/GI/c/n queues. To prove them we establish the general monotonicity property that increasing the waiting room and/or the number of servers in a /GI/c/n queue increases the throughput. An asymptotic result on the number of busy servers is obtained as a consequence of the bounds. Numerical evidence as well as an application to optimal design illustrates the potential usefulness for engineering purposes. The proof is based on a sample path argument.

OPTIMAL DESIGN PARAMETERS OF RECONFIGURABLE ROBOTS WITH LOCKABLE JOINTS

2017 ◽  
Vol 41 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Gabriel Zeinoun ◽  
Ramin Sedaghati ◽  
Farhad Aghili
Keyword(s):  
Genetic Algorithm ◽  
Sequential Quadratic Programming ◽  
Maximum Velocity ◽  
Upper Bounds ◽  
Design Parameters ◽  
Lower And Upper Bounds ◽  
End Effector ◽  
Reconfigurable Robots ◽  
Manipulability Measure ◽  
Optimization Methodology

This paper presents a global optimization methodology to find the optimal Denavit–Hartenberg parameters of a serial reconfigurable manipulator minimizing a cost function over a pre-specified workspace volume and given lower and upper bounds on the design parameters. Different cost functions such as the manipulability measure, maximum force capability of the manipulator’s end-effector, and maximum velocity capability of the manipulator within the operating workspace of the manipulator are considered to optimize the kinematic design. Based on a combination of genetic algorithm (GA) and sequential quadratic programming (SQP), a modified global and posture-independent parameter of singularity (MPIPS) is presented. Finally, a weighted objective function is proposed to balance between the conflicting requirements for manipulator’s force and velocity capabilities.

Behaviors of Composite Circular Struts in Space Environment: Analyses and Experiments

2004 ◽  
Vol 261-263 ◽  
pp. 797-802
Author(s):  
Chul Kim ◽  
Jong Heun Lee ◽  
J.H. Kim ◽  
Hoon Sang Choi
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Composite Materials ◽  
Optimal Design ◽  
Thermal Analyses ◽  
Space Environment ◽  
Stacking Sequence ◽  
Finite Element Analyses ◽  
Axial Deformation ◽  
Generic Algorithms

The optimal stacking sequence and wall thickness of the composite strut tubes were determined to minimize thermal strains during orbital operation using generic algorithms and finite element analyses. From the results of previous thermal analyses of composite struts with various stacking sequences, the axial deformation is a matter of prime importance. For this reason, the optimization focuses to minimize the axial strains. The balanced and symmetric stacking sequences are used to minimize the radial and the twisting deformations. The genetic algorithm is known to be very effective for the discrete optimization such as stacking sequences of composite materials. As a result, the thermal deformations of the strut with an optimal stacking sequence are almost zero. The optimal strut tube consists of 6 plies and the weight of a composite strut is 22.4% that of aluminum strut. Finite element analyses showed that the optimal design of composite strut tubes withstood combined launch loads without buckling and failure. To validate the analyses, four composite struts were fabricated and their thermal strains were measured under the temperature increase of 100°C. The thermal and vibration experiments showed excellent correlations with analytical results.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

Energy of spherical fuzzy graphs

2020 ◽  
pp. 321-332
Author(s):  
S. Yahya Mohamed ◽  
A. Mohamed Ali
Keyword(s):  
Adjacency Matrix ◽  
Upper Bounds ◽  
Fuzzy Graph ◽  
Lower And Upper Bounds ◽  
Fuzzy Graphs

In this paper, the notion of energy extended to spherical fuzzy graph. The adjacency matrix of a spherical fuzzy graph is defined and we compute the energy of a spherical fuzzy graph as the sum of absolute values of eigenvalues of the adjacency matrix of the spherical fuzzy graph. Also, the lower and upper bounds for the energy of spherical fuzzy graphs are obtained.

scholarly journals Relationship between Age and Value of Information for a Noisy Ornstein–Uhlenbeck Process

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 940
Author(s):  
Zijing Wang ◽  
Mihai-Alin Badiu ◽  
Justin P. Coon
Keyword(s):  
Value Of Information ◽  
Markov Models ◽  
Upper Bounds ◽  
Distribution Functions ◽  
Lower And Upper Bounds ◽  
Uhlenbeck Process ◽  
Source Data ◽  
Non Linear ◽  
Queue Model ◽  
Selection Of

The age of information (AoI) has been widely used to quantify the information freshness in real-time status update systems. As the AoI is independent of the inherent property of the source data and the context, we introduce a mutual information-based value of information (VoI) framework for hidden Markov models. In this paper, we investigate the VoI and its relationship to the AoI for a noisy Ornstein–Uhlenbeck (OU) process. We explore the effects of correlation and noise on their relationship, and find logarithmic, exponential and linear dependencies between the two in three different regimes. This gives the formal justification for the selection of non-linear AoI functions previously reported in other works. Moreover, we study the statistical properties of the VoI in the example of a queue model, deriving its distribution functions and moments. The lower and upper bounds of the average VoI are also analysed, which can be used for the design and optimisation of freshness-aware networks. Numerical results are presented and further show that, compared with the traditional linear age and some basic non-linear age functions, the proposed VoI framework is more general and suitable for various contexts.

Sign in / Sign up

Export Citation Format

Share Document