R. Bruce Floersheim, Gene Hou and Kent Firestone
The purpose of this paper is to characterize the material properties of carbon fiber polyamide composite (CFPC) used in a 3D rapid prototyping process based upon selective laser…
Abstract
Purpose
The purpose of this paper is to characterize the material properties of carbon fiber polyamide composite (CFPC) used in a 3D rapid prototyping process based upon selective laser sintering (SLS) and demonstrate that the SLS process introduces a bias in the micro‐fiber orientation such that the CFPC solid is an orthotropic structural material.
Design/methodology/approach
Material coupons for tensile tests from each of the orthogonal planes are created using the SLS process. After tensile testing, the coupons are examined under scanning electron microscopy to verify the micro‐fiber orientation bias. A complex 3D structure developed utilizing the CFPC material is subjected to modal testing to extract the natural frequencies. These frequencies are compared to predictive numerical analysis results from computer‐aided engineering (CAE) software to validate the coupon test results.
Findings
This paper proves that the CFPC solid material is orthotropic after the SLS process and that the process itself creates bias in the micro‐fiber orientation. Predictions of natural frequencies from CAE software for a complex 3D structure created from CFPC are within 2 percent of the actual natural frequencies determined during modal testing.
Practical implications
The paper has determined the tensile material characteristics of solid CFPC correcting the original material data sheet information which lists the solid CFPC as isotropic with much stronger tensile characteristics. It has also provided evidence of the bias that SLS introduces to embedded micro‐fibers during the rapid‐prototyping process.
Originality/value
The paper deals with experimental work on determining the material characteristics of a relatively new composite material for which very little test data exists in literature. In particular, an original contribution is demonstration of the micro‐fiber orientation bias introduced by the SLS process.
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Zhimin Hou, Markus Philipp, Kuangen Zhang, Yong Guan, Ken Chen and Jing Xu
This paper aims to present an optimization algorithm combined with the impedance control strategy to optimize the robotic dual peg-in-hole assembly task, and to reduce the…
Abstract
Purpose
This paper aims to present an optimization algorithm combined with the impedance control strategy to optimize the robotic dual peg-in-hole assembly task, and to reduce the assembly time and smooth the contact forces during assembly process with a small number of experiments.
Design/methodology/approach
Support vector regression is used to predict the fitness of genes in evolutionary algorithm, which can reduce the number of real-world experiments. The control parameters of the impedance control strategy are defined as genes, and the assembly time is defined as the fitness of genes to evaluate the performance of the selected parameters.
Findings
The learning-based evolutionary algorithm is proposed to optimize the dual peg-in-hole assembly process only requiring little prior knowledge instead of modeling for the complex contact states. A virtual simulation and real-world experiments are implemented to demonstrate the effectiveness of the proposed algorithm.
Practical implications
The proposed algorithm is quite useful for the real-world industrial applications, especially the scenarios only allowing a small number of trials.
Originality/value
The paper provides a new solution for applying optimization techniques in real-world tasks. The learning component can solve the data efficiency of the model-free optimization algorithms.
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Damian Tago, Henrik Andersson and Nicolas Treich
This study contributes to the understanding of the health effects of pesticides exposure and of how pesticides have been and should be regulated.
Abstract
Purpose
This study contributes to the understanding of the health effects of pesticides exposure and of how pesticides have been and should be regulated.
Design/methodology/approach
This study presents literature reviews for the period 2000–2013 on (i) the health effects of pesticides and on (ii) preference valuation of health risks related to pesticides, as well as a discussion of the role of benefit-cost analysis applied to pesticide regulatory measures.
Findings
This study indicates that the health literature has focused on individuals with direct exposure to pesticides, i.e. farmers, while the literature on preference valuation has focused on those with indirect exposure, i.e. consumers. The discussion highlights the need to clarify the rationale for regulating pesticides, the role of risk perceptions in benefit-cost analysis, and the importance of inter-disciplinary research in this area.
Originality/value
This study relates findings of different disciplines (health, economics, public policy) regarding pesticides, and identifies gaps for future research.
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Adil Baykasoglu and Cengiz Baykasoglu
The purpose of this paper is to develop a new multi-objective optimization procedure for crashworthiness optimization of thin-walled structures especially circular tubes with…
Abstract
Purpose
The purpose of this paper is to develop a new multi-objective optimization procedure for crashworthiness optimization of thin-walled structures especially circular tubes with functionally graded thickness.
Design/methodology/approach
The proposed optimization approach is based on finite element analyses for construction of sample design space and verification; gene-expression programming (GEP) for generating algebraic equations (meta-models) to compute objective functions values (peak crash force and specific energy absorption) for design parameters; multi-objective genetic algorithms for generating design parameters alternatives and determining optimal combination of them. The authors have also utilized linear and non-linear least square regression meta-models as a benchmark for GEP.
Findings
It is shown that the proposed approach is able to generate Pareto optimal designs which are in a very good agreement with the actual results.
Originality/value
The paper presents the application of a genetic programming-based method, namely, GEP first time in the literature. The proposed approach can be used to all kinds of related crashworthiness problems.
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Niloufar Azhdari, Seyed Shaker Hashemi, Saber Ezzi, Kabir Sadeghi and Abdoreza Fazeli
Ongoing research indicates that structures with infill panels manifest distinct seismic responses, necessitating further investigation. This study aims to introduce a novel…
Abstract
Purpose
Ongoing research indicates that structures with infill panels manifest distinct seismic responses, necessitating further investigation. This study aims to introduce a novel methodology for determining the response modification factor (RMF) of reinforced concrete (RC) moment-resisting frames and investigate the impact of infill sandwich panels on these structures.
Design/methodology/approach
Using SAP2000 software, 84 RC frames were meticulously designed and analyzed, followed by the development of a predictive model using genetic programming and GeneXpro Tools software to calculate the RMF values. The results underscore the efficacy of gene expression programming (GEP) in determining the RMF of RC moment-resisting frames.
Findings
The study’s results reveal that the variations in the yield stress of longitudinal reinforcements within the range of 340 to 400 MPa and changes in the design base acceleration have a minimal impact on the RMF value. For RC moment-resisting frames with infill sandwich panels, the RMF value decreases as the span length to storey height ratio (L/H) increases, while it increases with a higher number of storeys. Conversely, for RC frames without infill sandwich panels, the RMF decreases with an increase in the number of storeys. However, no consistent pattern emerges for the RMF with changes in the L/H ratio, highlighting the nonuniform effect of altering this ratio on RMF.
Originality/value
The proposed formula in this study is very effective in predicting the RMF and can assist engineers in the seismic design of RC structures.
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Yuemin Hou and Linhong Ji
The aim is to map function into structure step‐by‐step.
Abstract
Purpose
The aim is to map function into structure step‐by‐step.
Design/methodology/approach
Using bio‐inspired approach to investigate generic principle governing the formation of systems or artifacts by analogy with embryogenesis and using matrices and graphs to formalize design information.
Findings
A six‐stage design framework is proposed and represented as six models: the function model which interprets design requirements, the surrogate model which transforms the subjective intention into the objective property, the property model which illustrates basic constituents of property, the specification model which specifies abstract properties by concrete property values or equations, the feature model which transforms properties into the feature of topology and materials of the structure, and the parameter model which parameterizes the detail description of structure. The transformations between stages are achieved mainly by means of induction, duality, decision making and nonlinear programming.
Research limitations/implications
Bio‐inspired approach provides mechanisms to map function into structure.
Practical implications
A normative framework for engineering design and system design.
Originality/value
The framework distinguishes itself by biological approach, developmental process simulating to the development of embryo, induction and duality strategies to map stages, as well as mathematical representation.
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This study aims to solve the problem of job scheduling and multi automated guided vehicle (AGV) cooperation in intelligent manufacturing workshops.
Abstract
Purpose
This study aims to solve the problem of job scheduling and multi automated guided vehicle (AGV) cooperation in intelligent manufacturing workshops.
Design/methodology/approach
In this study, an algorithm for job scheduling and cooperative work of multiple AGVs is designed. In the first part, with the goal of minimizing the total processing time and the total power consumption, the niche multi-objective evolutionary algorithm is used to determine the processing task arrangement on different machines. In the second part, AGV is called to transport workpieces, and an improved ant colony algorithm is used to generate the initial path of AGV. In the third part, to avoid path conflicts between running AGVs, the authors propose a simple priority-based waiting strategy to avoid collisions.
Findings
The experiment shows that the solution can effectively deal with job scheduling and multiple AGV operation problems in the workshop.
Originality/value
In this paper, a collaborative work algorithm is proposed, which combines the job scheduling and AGV running problem to make the research results adapt to the real job environment in the workshop.
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Amir H. Hashemian, Mohammad H. Kargarnovin and Jafar E. Jam
The purpose of this paper is to analyze a squared lattice cylindrical shell under compressive axial load and to optimize the geometric parameters to achieve the maximum buckling…
Abstract
Purpose
The purpose of this paper is to analyze a squared lattice cylindrical shell under compressive axial load and to optimize the geometric parameters to achieve the maximum buckling load. Also a comparison between buckling loads of a squared lattice cylinder and a solid hollow cylinder with equal weight, length and outer diameter is performed to reveal the superior performance of the squared lattice cylindrical shells.
Design/methodology/approach
A cylindrical lattice shell includes circumferential and longitudinal rods with geometric parameters such as cross‐section areas of the rods, distances and angles between them. In this study, the governing differential equation for buckling load which can be presumed as a criterion for designing lattice structures with a specific weight is derived and is used as an objective function in genetic algorithm (GA) method to calculate the optimum geometric parameters of the shell. The optimum parameters were modelled in finite element method (FEM) in order to verify the buckling loads obtained from GA. In another effort, the FEM was applied to analyze the solid hollow cylinders.
Findings
The results demonstrate relatively close agreement between the buckling loads obtained from GA and FEM for such shells. It was also shown that latticed cylinders have better performance to carry compressive axial loads than the equivalent solid hollow cylinders with equal weights, lengths and outer diameters.
Research limitations/implications
The studies reported in this paper have been carried out for a single squared lattice shell without using two‐side skins. However, using skins can give better performance in carrying compressive axial loads.
Practical implications
The results in this paper show that this type of effective, economical lightweight and functional structures could be applied as inter‐stages, inter‐tanks, aircraft fuselage, rocket motor cases, pressure vessels and other elements of civil engineering structures in order to have greater strength and lower weight.
Originality/value
Squared lattice cylindrical shell with optimum geometric design could provide the chance for eliminating the stiffeners of shells in aerospace structures in order to decrease the weight and increase the load‐bearing capacity.
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Salim Ahmed, Khushboo Kumari and Durgeshwer Singh
Petroleum hydrocarbons are naturally occurring flammable fossil fuels used as conventional energy sources. It has carcinogenic, mutagenic properties and is considered a hazardous…
Abstract
Purpose
Petroleum hydrocarbons are naturally occurring flammable fossil fuels used as conventional energy sources. It has carcinogenic, mutagenic properties and is considered a hazardous pollutant. Soil contaminated with petroleum hydrocarbons adversely affects the properties of soil. This paper aim to remove pollutants from the environment is an urgent need of the hour to maintain the proper functioning of soil ecosystems.
Design/methodology/approach
The ability of micro-organisms to degrade petroleum hydrocarbons makes it possible to use these microorganisms to clean the environment from petroleum pollution. For preparing this review, research papers and review articles related to petroleum hydrocarbons degradation by micro-organisms were collected from journals and various search engines.
Findings
Various physical and chemical methods are used for remediation of petroleum hydrocarbons contaminants. However, these methods have several disadvantages. This paper will discuss a novel understanding of petroleum hydrocarbons degradation and how micro-organisms help in petroleum-contaminated soil restoration. Bioremediation is recognized as the most environment-friendly technique for remediation. The research studies demonstrated that bacterial consortium have high biodegradation rate of petroleum hydrocarbons ranging from 83% to 89%.
Social implications
Proper management of petroleum hydrocarbons pollutants from the environment is necessary because of their toxicity effects on human and environmental health.
Originality/value
This paper discussed novel mechanisms adopted by bacteria for biodegradation of petroleum hydrocarbons, aerobic and anaerobic biodegradation pathways, genes and enzymes involved in petroleum hydrocarbons biodegradation.