Structural Optimization Program Research Articles

Custom software development of structural dimension optimization software for the buckling of stiffened plates

<abstract> <p>Existing structural optimization software tools only integrate the Euler buckling function of rods and plates and do not consider the buckling strength constraint of stiffened plates, thus failing to meet the optimization design requirements of thin-walled structures such as ship hulls. In this study, according to the buckling strength specifications for stiffened plates of ships, the custom software development of a structural optimization program with "buckling constraints of stiffened plates" was performed using the HyperMesh optimization design software. The finite-element grid of the stiffened plate was divided; the average stress, stress gradient and other parameters associated with the buckling of stiffened plates were determined; the DRESP3 card was set; the external OML function file was linked and the buckling strength of the stiffened plates was introduced into the dimensional optimization design model as a constraint. The proposed method was used to optimize the structure scantlings of a platform, achieving a reduction of 8.96% compared with the original scheme, while also meeting the requirements of structural strength, deformation and buckling strength. The results demonstrated that the dimensional optimization software with buckling constraints is operable and can aid in the rapid structural optimization design of stiffened plates.</p> </abstract>

Design, Synthesis, and Physicochemical and Pharmacological Profiling of 7-Hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamide Derivatives with Antiosteoarthritic Activity In Vivo.

The hallmark of joint diseases, such as osteoarthritis (OA), is pain, originating from both inflammatory and neuropathic components, and compounds able to modulate the signal transduction pathways of the cannabinoid type-2 receptor (CB2R) can represent a helpful option in the treatment of OA. In this perspective, a set of 18 cannabinoid type-2 receptor (CB2R) ligands was developed based on an unprecedented structure. With the aim of improving the physicochemical properties of previously reported 4-hydroxy-2-quinolone-3-carboxamides, a structural optimization program led to the discovery of isosteric 7-hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamide derivatives. These new compounds are endowed with high affinity for the CB2R and moderate to good selectivity over the cannabinoid type-1 receptor (CB1R), associated with good physicochemical characteristics. As to the functional activity at the CB2R, compounds able to act either as agonists or as inverse agonists/antagonists were discovered. Among them, compound 51 emerged as a potent CB2R agonist able to reduce pain in rats carrying OA induced by injection of monoiodoacetic acid (MIA).

Identification of dual Sigma1 receptor modulators/acetylcholinesterase inhibitors with antioxidant and neurotrophic properties, as neuroprotective agents

In this manuscript we report on the design, synthesis and evaluation of dual Sigma 1 Receptor (S1R) modulators/Acetylcholinesterase (AChE) inhibitors endowed with antioxidant and neurotrophic properties, potentially able to counteract neurodegeneration. The compounds based on arylalkylaminoketone scaffold integrate the pharmacophoric elements of RRC-33, a S1R modulator developed by us, donepezil, a well-known AChE inhibitor, and curcumin, a natural antioxidant compound with neuroprotective properties. A small library of compounds was synthesized and preliminary in vitro screening performed. Some compounds showed good S1R binding affinity, selectivity towards S2R and N-Methyl-d-Aspartate (NMDA) receptor, AChE relevant inhibiting activity and are potentially able to bypass the BBB, as predicted by the in silico study. For the hits 10 and 20, the antioxidant profile was assessed in SH-SY5Y human neuroblastoma cell lines by evaluating their protective effect against H2O2 cytotoxicity and reactive oxygen species (ROS) production. Tested compounds resulted effective in decreasing ROS production, thus ameliorating the cellular survival. Moreover, compounds 10 and 20 showed to be effective in promoting the neurite elongation of Dorsal Root Ganglia (DRG), thus demonstrating a promising neurotrophic activity. Of note, the tested compounds did not show any cytotoxic effect at the concentration assayed. Relying on these encouraging results, both compounds will undergo a structure optimization program for the development of therapeutic candidates for neurodegenerative diseases treatment.

Structure Optimization Model of Comprehensive Transport Corridor Based on Resource Constraints

From the manager and the traveler’s point of view, a bi-level programming model of structure optimization considering multi factors is proposed for comprehensive transportation corridor with parallel structure. In the higher level model, land resource consumption, upper model energy consumption and environmental emissions as indicators are selected as indexes to minimize the social resource cost. In the lower level model, the Mode-Path User Equilibrium model is selected for traffic distribution. To minimize the total travel cost of travelers, the supply and demand balance coefficient is selected as the channel response function and a model solution algorithm is designed based on genetic algorithm. At last, the proposed model is applied to Zhejiang Province Hangzhou Ningbo transportation corridor. The channel traffic demand is calculated for the planning year and the reasonable channel structure optimization program is given, which proves that the model is scientific and effective.

Multi-objective sizing and topology optimization of truss structures using genetic programming based on a new adaptive mutant operator

Most real-world engineering problems deal with multiple conflicting objectives simultaneously. In order to address this issue in truss optimization, this paper presents a multi-objective genetic programming approach for sizing and topology optimization of trusses. It aims to find the optimal cross-sectional areas and connectivities between the nodes to achieve a set of trade-off solutions to satisfy all the optimization objective functions subjected to some constraints such as kinematic stability, maximum allowable stress in members and nodal deflections. It also uses the variable-length representation of potential solutions in the shape of computer programs and evolves to the potential final set of solutions. This approach also employs an adaptive mutant factor besides the classical genetic operators to improve the exploring capabilities of Genetic Programming in structural optimization. The intrinsic features of genetic programming help to identify redundant truss members and nodes in the design space, while no violation of constraints occurs. Our approach applied to some numerical examples and found a better non-dominated solution set in the most cases in comparison with the competent methods available in the literature.

EVALUATION OF A BONE REINFORCEMENT TECHNIQUE USING FINITE ELEMENT ANALYSIS.

ABSTRACTObjectives:To compare the results of a simulated fall on the greater trochanter in the proximal portion of a synthetic femur before and after femoral reinforcement with tricalcium phosphate bone cement (TP) and polymethyl methacrylate (PMMA), using finite element analysis (FEA). Methods:Using two synthetic proximal femurs, a FEA simulating a fall on the greater trochanter was performed, using the Bi-directional Evolutionary Structural Optimization (BESO) program. For this analysis, the femurs were filled with TP and PMMA after perforations were created in the trochanteric region and neck. The results were compared with the strength values obtained from testing the control specimen, a synthetic bone without reinforcement. Results:FEA showed a value of 600 N prior to reinforcement. After cementing with PMMA, the load increased by 57.5% (945 N), and by 53% (920 N) after cementing with TP. Conclusion:Synthetic femurs gained resistance to fracture-causing forces in a simulated fall on the trochanter after bone reinforcement with PMMA and TP. Level of Evidence III; Experimental study.

Multi-stage optimization method for air-intake system of hovercraft based on autonomous optimization

In this study, an optimal structural design program was designed and developed for Computational Fluid Dynamics based on self-optimization, effectively reducing the time required for structural optimization. Through experimental design using this program, the effects of various design variables on the optimization objectives were evaluated, and an adaptive simulated annealing algorithm was used for global optimization. Furthermore, response surface methodology and a nonlinear quadratic programming algorithm were utilized to obtain a global optimum solution after repeated iterations. Moreover, using a hovercraft air-intake system as the optimized object, the total pressure loss of the system was completely optimized by using a porous medium model and Matlab analysis program, and the accuracy of the structural design optimization program was validated. After the global optimization, the total pressure loss of the air-intake system was reduced by 20.5% compared to the original model. An average nonuniformity of 4.36% of engine inlet speed and 5% local nonuniformity of 11.19% satisfy the design requirements of the hovercraft engine. This method can be directly applied to engineering optimization problems as well as multiobjective optimization tasks after improving the relevant methodologies.

312 座屈を考慮したパネル構造物の構造最適化プログラムの開発とその有効性の検討(OS1-2 最適設計と解析)

312 座屈を考慮したパネル構造物の構造最適化プログラムの開発とその有効性の検討(OS1-2 最適設計と解析)

Research on current situation of cultural development and future development trend of “South Lion”

This paper obtains the influence factors of cultural development of South Lion through the construction of a multi-index fixed-weight hierarchical structure model, analysis of cultural development issues of South Lion in China, and the relevant survey. This paper subsequently proposes a more effective structure optimization program through fixed-weight analysis and combined with the limitations of cultural development. That is, the future development strategies of South Lion in China should be as follows: to construct the public cultural development system of South Lion, regulate the cultural education of South Lion, and increase the courses offered, develop the public interest and cultivate the talents and strengthen the culture commercial development of South Lion.

Genetic algorithm optimization of defect clusters in crystalline materials

A real-space genetic algorithm for the optimization of defect structures embedded in bulk crystalline materials is developed. The purpose of this method is to enable automated prediction of stable structures for a range of embedded clusters, including radiation induced defect clusters, dopant clusters, and small precipitates. The method is applied to the prediction of small interstitial clusters in cubic SiC, BCC Fe, and BCC Fe–Cr random alloys for radiation damage applications. The performance of the method is analyzed and compared to alternative techniques such as basin hopping. The technique is able to reproduce small-size defects that had been previously identified as stable or metastable structures as well as predict new mid-size defects. The structure optimization program (StructOpt) developed in this study is available under open source licensing as part of the MAterials Simulation Toolkit (MAST) and can be obtained from https://pypi.python.org/pypi/MAST.

AN INTRODUCTION TO THE TECHNIQUES OF STRUCTURAL OPTIMISATION

In the past consideration has been given to applying structural optimization programs to design, but performance has been disappointing. This paper demonstrates how the situation has improved due to the ready availability of cheap computing power, the existence of efficient finite element analysis systems and recent developments in optimisation algorithms. Examples are given of using specific algorithms in carbon fibre composite wings and fuselage. The paper concludes with the author's ideas on how the techniques will be applied in the future.

Rational Land Planning Utilization Structure Optimization Based on Multi-Objective Linear Programming Model of Foshan

Regional land use/cover change is one of the hot issues of the global research. Since the proposal of “land use/cover change” research program by the International Geosphere-Biosphere Program（IGBP）and International Human Dimensions Programme on Global Environmental Change（IHDP）in 1995, the research on the land use structure optimization has been increasingly important as the core issue of regional land use/cover change. The structural optimization of land use refers to the use of certain techniques and methods to make the regional future land use structure achieve the best economic, ecological and social benefits. Base on the multi-objective linear programming model and through the setting of 14 variables, this paper has proposed the land use structural optimization program for the rational land planning of Foshan, thus providing reference for the rational land planning of economically developed area.

Optimal Design of a Scroll Case with Natural Frequency Constraints

In this paper, sensitivity formula with analytical method is derived for calculating structural natural frequency, and the partial derivative of plate element stiffness matrix and mass matrix with respect to design variables are gained respectively. Computer programs for computing frequency sensitivity with analytical method are developed. And combining it with large finite element structural analysis software ADINA, the optimal design software based on genetic algorithms, a structural dynamic optimization program system is constituted for computing structural natural frequency sensitivity with analytical method. Finally, the program system is applied to the optimal design of a turbine scroll case of a hydropower station (taking into account the natural frequency constraints). Calculation results show that analytical method presented in the paper is of higher computational precision, good stability, convenient to use, and can be popularized. Calculation results obtained the approval of client and used in real engineering.

Study on Searching the Best Rise of Truss String Structure by Using Fibonacci Method

In order to discuss the relationship between truss string structure weight and the rise, so as to find out the optimal rise of different spans, Fibonacci search method is used to write truss string structure optimization program which takes the rise as variable. To effectively improve search efficiency and ensure the accuracy, the dynamic search interval is introduced when writing the Fibonacci search program. This paper use Fibonacci to search the optimal rise in span of 100m of truss string structure, meanwhile analysis the dynamic search interval, the analysis results show that the approximate solutions of this method is very approximate to exact solutions, and search efficiency is improved.

RESTRUCTURING THE STATE-OWNED ENTERPRISE SECTOR IN CHINA: EFFORTS, EFFECTS AND REMAINING CHALLENGES

This paper provides an analytical account of the restructuring of China's state-owned enterprise (SOE) sector during the period of 1994–2002 with the intention to obtain an understanding of how China's SOE sector has been restructured, how effective it has been, and what challenges remain. In particular, it documents the design and implementation of three key programs, namely, the Capital Structure Optimization Program, the establishment and operation of assets management corporations, and ownership transformation of small and large SOEs. This is put in perspective by a historical backdrop on how the SOE sector has been financed and what this has meant to SOE sector restructuring in terms of necessity and constraints. In assessing the effectiveness of restructuring with sector and province level data, this paper found strong evidence indicating that passive restructuring characterized by labor downsizing has taken place extensively, and labor productivity has been improved significantly. However, the data lend no support to any significant impact of restructuring on overall efficiency of the SOE sector when sector-wide factors are controlled for, suggesting that innovative operational restructuring may have been either very limited or unsuccessful. Major challenges remain for the Chinese government to cope with. In particular, financial resources are urgently needed to fund labor settlement and recognize and write off the loss associated with non-performing loans; qualified new owners have to be put in place to launch and lead operational restructuring; and institutions such as bankruptcy regime need to be developed urgently.

An ab initio study on the atomic geometry of reconstructed Ge( [formula omitted])16×2 surface

In order to understand the atomic geometry of 16 × 2 superstructure reconstructed on clean Ge(1 1 0) surfaces, a 16 × 2 structural model was proposed, based on scanning tunneling microscopic (STM) observations, and relaxed by using an ab initio structure optimization program. STM images calculated from the relaxed model could well explain features of experimental STM images, which indicates that five-membered clusters of Ge adatoms are entities of pentagons observed in the STM images.

1403 3 次元オートメッシュジェネレータ 「CLAY DIVIDER」, 「CLAY MESH」 および構造最適化ソフトウェア 「CLAY OPERA」

We develop the CLAY DIVIDER, the CLAY and the CLAY OPERA. The CLAY DIVIDER is There Dimension Shell Element Auto Mesh Generator. A feature is No-Healing of CAD using "Virtual Zone". The CLAY MESH is Three Dimension Solid Element Auto Mesh Generator. A feature is Voxel Mesh Generator mixed tetra, penta and hexa element for possible structure analysis. The CLAY OPERA is the structure optimization program using Basis Vector Method. The Basis Vector Model is created using a morphing technique on CLAY OPERA. These papers report a summary of The CLAY Series using some example of CAD Shape.

A method for selecting optimal sections for members of skeletal structures

This paper presents a simple method for selecting optimal sections for members of skeletal structures from an initially given set of sections. This is an extension of evolutionary structural optimization (ESO) to the sizing optimization problem with discrete design variables. Member sensitivity index for section sizing is derived from the optimality criterion. Optimization process is an iterative process of analysis, sensitivity calculation and section selection until optimality criterion is satisfied or constraints are violated. The proposed optimization procedure has been implemented into a structural analysis and optimization program called FEMOPT written on MATLAB programming language. Illustrative examples demonstrate the effectiveness of the proposed method.

Crash analyses and design of a belt integrated seat for occupant safety

The performance of a belt integrated seat (BIS) is evaluated by using a sled test and occupant analysis software. The seat belt is attached to the seat back in the BIS to improve occupant safety. A simulation model of a BIS is established by using an occupant analysis program, SAFE. The model is constructed on the basis of data obtained from the structural investigation and a frontal sled test of a BIS. The numerical result from the simulation model is validated for consistency by comparison with high speed photographs taken during the sled test. Characteristics of both the conventional seat and the BIS are discussed. It is shown that occupant safety can be improved considerably with the BIS. A parametric study is conducted for various seat belts and a recommendation for an appropriate one is proposed. Structural analysis and optimization of the BIS are performed to establish the preliminary design trend considering occupant safety. A finite element model of the BIS is created, and the structure is optimized by the structural analysis and optimization program GENESIS. The seat components are reinforced on the basis of the shape of the existing BIS product. The results are discussed and a design recommendation for a BIS is made.

Stochastic bilevel programming in structural optimization

We consider the mathematical modelling and solution of robust and cost-optimizing structural (topology) design problems. The setting is the optimal design of a linear-elastic structure, for example a truss topology, under unilateral frictionless contact, and under uncertainty in the data describing the load conditions, the material properties, and the rigid foundation. The resulting stochastic bilevel optimization model finds a structural design that responds the best to the given probability distribution in the data. This model is of special interest when a structural failure will lead to a reconstruction cost, rather than loss of life. For the mathematical model, we provide results on the existence of optimal solutions which allow for zero lower design bounds. We establish that the optimal solution is continuous in the lower design bounds, a result which validates the use of small but positive values of them, and for such bounds we also establish the locally Lipschitz continuity and directional differentiability of the implicit upper-level objective function. We also provide a heuristic algorithm for the solution of the problem, which makes use of its differentiability properties and parallelization strategies across the scenarios. A small set of numerical experiments illustrates the behaviour of the stochastic solution compared to an average-case deterministic one, establishing an increased robustness.