Intelligent wheeled mobile robots for blind navigation applicationWu, Ter-Feng; Tsai, Pu-Sheng; Hu, Nien-Tsu; Chen, Jen-Yang
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-08-2015-0256
PurposeVisually impaired people have long been living in the dark. They cannot realize the colorful world with their vision, so they rely on hearing, touch and smell to feel the space they live in. Lacking image information, they face challenges in the external environment and barrier spaces. They face danger that is hundreds of times higher than that faced by normal people. Especially during outdoor activities, they can only explore the surrounding environment aided by their hearing and crutches and then based on a vague impression speculate where they are located. To let the blind confidently take each step, this paper proposes sticking the electronic tag of the radio-frequency identification (RFID) system on the back of guide bricks.Design/methodology/approachThus, the RFID reader, ultrasonic sensor and voice chip on a wheeled mobile robot link the front end to the crutch. Once the blind person nears a guide brick, the RFID will read the message on the tag through the voice broadcast system, and a voice will inform the visually impaired person of the direction to walk and information of the surrounding environment. In addition, the CMOS image sensor set up in the wheeled mobile robot is used to detect the black marking on the guide brick and to guide the blind to walk forward or turn around between the two markings. Finally, the lithium battery charging control unit was installed on the wheeled mobile robot. The ATtiny25 microcontroller conducts the battery charge and discharge control and monitoring of the current battery capacity.FindingsThe development of this system will let visually impaired people acquire environmental information, road guidance function and nearby traffic information.Originality/valueThrough rich spatial environment messages, the blind can have the confidence and courage to go outside.
Automatic tunable deployment for real-time strategy gamesYang, Cheng-Ta; Yeh, Her-Tyan; Chen, Bing-Chang; Jian, Guo-Xiang
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-08-2015-0251
PurposeExtensive efforts have been conducted on the real-time strategy (RTS) games. The purpose of this paper is the specific artificial intelligence (AI) challenges posed by RTS games; non-player character (NPC) is started out by collecting game-map resources to build up defenses and attack forces, to upgrade combat deployment.Design/methodology/approachThe authors used weak AI fuzzy theory as the foundation for tunable development. With the fuzzy theory, the AI was more humanistic in its judgment process.FindingsWell-developed AIs have been used brilliantly in various aspects in RTS games, especially in those developed by large production teams. For small production teams, how to develop an AI system in less time and at a lower cost is extremely important.Research limitations/implicationThis study aimed to develop a system using player unit threat levels for NPC deployment and arrangement so that the further strategy would be adopted for NPCs in response to player actions.Originality/valueThe RTS games would become more challenging for players to play.
Low-order mixed finite element analysis of progressive failure in pressure-dependent materials within the framework of the Cosserat continuumTang, Hongxiang; Guan, Yuhui; Zhang, Xue; Zou, Degao
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-11-2015-0370
PurposeThis paper aims to develop a finite element analysis strategy, which is suitable for the analysis of progressive failure that occurs in pressure-dependent materials in practical engineering problems.Design/methodology/approachThe numerical difficulties stemming from the strain-softening behaviour of the frictional material, which is represented by a non-associated Drucker–Prager material model, is tackled using the Cosserat continuum theory, while the mixed finite element formulation based on Hu–Washizu variational principle is adopted to allow the utilization of low-order finite elements.FindingsThe effectiveness and robustness of the low-order finite element are verified, and the simulation for a real-world landslide which occurred at the upstream side of Carsington embankment in Derbyshire reconfirms the advantages of the developed elastoplastic Cosserat continuum scheme in capturing the entire progressive failure process when the strain-softening and the non-associated plastic law are involved.Originality/valueThe permit of using low-order finite elements is of great importance to enhance computational efficiency for analysing large-scale engineering problems. The case study reconfirms the advantages of the developed elastoplastic Cosserat continuum scheme in capturing the entire progressive failure process when the strain-softening and the non-associated plastic law are involved.
Using the buck-interleaved buck–boost converter to implement a step-up/down inverterChang, Chien-Hsuan; Cheng, Hung-Liang; Chang, En-Chih
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-08-2015-0241
PurposeA typical photovoltaic grid-connection power system usually consists of multi-stage converters to perform multiple functions simultaneously. To simplify system configuration, reduce cost and improve conversion efficiency, this paper aims to develop a buck–boost-type inverter. The proposed inverter has both step-up and step-down functions, so that it is suitable for applications with wide voltage variation. As only one power switch operates with high frequency at one time, switching losses can significantly be reduced.Design/methodology/approachA step-up/down inverter is developed by adopting a buck-interleaved buck–boost (BuIBB) DC-DC converter and connecting with an H-bridge unfolding circuit with line-commutated operation.FindingThe proposed circuit can work functionally as either a buck-type or boost-type inverter, so that partial energy can be directly delivered to output to improve efficiency. The input current is shared by two inductors, leading to the reduction of current stresses.Research limitations/implicationsTo apply the proposed inverter to micro-inverter applications in the future, developing a step-up/down inverter with a higher conversion ratio will be considered.Practical implicationsA laboratory prototype is built accordingly to verify the feasibility of the proposed inverter. The experimental results are presented to show the effectiveness.Originality/valueThis paper proposes a step-up/down inverter by using the BuIBB converter, which is innovatively studied.
A Krylov enhanced proper orthogonal decomposition method for frequency domain model reductionBinion, David; Chen, Xiaolin
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-11-2015-0344
PurposeThis paper aims to describe a method for efficient frequency domain model order reduction. The method attempts to combine the desirable attributes of Krylov reduction and proper orthogonal decomposition (POD) and is entitled Krylov enhanced POD (KPOD).Design/methodology/approachThe KPOD method couples Krylov’s moment-matching property with POD’s data generalization ability to construct reduced models capable of maintaining accuracy over wide frequency ranges. The method is based on generating a sequence of state- and frequency-dependent Krylov subspaces and then applying POD to extract a single basis that generalizes the sequence of Krylov bases.FindingsThe frequency response of a pre-stressed microelectromechanical system resonator is used as an example to demonstrate KPOD’s ability in frequency domain model reduction, with KPOD exhibiting a 44 per cent efficiency improvement over POD.Originality/valueThe results indicate that KPOD greatly outperforms POD in accuracy and efficiency, making the proposed method a potential asset in the design of frequency-selective applications.
Efficient numerical simulation of injection mold filling with the lattice Boltzmann methodDeng, Lin; Liang, Junjie; Zhang, Yun; Zhou, Huamin; Huang, Zhigao
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-01-2016-0023
PurposeLattice Boltzmann method (LBM) has made great success in computational fluid dynamics, and this paper aims to establish an efficient simulation model for the polymer injection molding process using the LBM. The study aims to validate the capacity of the model for accurately predicting the injection molding process, to demonstrate the superior numerical efficiency in comparison with the current model based on the finite volume method (FVM).Design/methodology/approachThe study adopts the stable multi-relaxation-time scheme of LBM to model the non-Newtonian polymer flow during the filling process. The volume of fluid method is naturally integrated to track the movement of the melt front. Additionally, a novel fractional-step thermal LBM is used to solve the convection-diffusion equation of the temperature field evolution, which is of high Peclet number. Through various simulation cases, the accuracy and stability of the present model are validated, and the higher numerical efficiency verified in comparison with the current FVM-based model.FindingsThe paper provides an efficient alternative to the current models in the simulation of polymer injection molding. Through the test cases, the model presented in this paper accurately predicts the filling process and successfully reproduces several characteristic phenomena of injection molding. Moreover, compared with the popular FVM-based models, the present model shows superior numerical efficiency, more fit for the future trend of parallel computing.Research limitations/implicationsLimited by the authors’ hardware resources, the programs of the present model and the FVM-based model are run on parallel up to 12 threads, which is adequate for most simulations of polymer injection molding. Through the tests, the present model has demonstrated the better numerical efficiency, and it is recommended for the researcher to investigate the parallel performance on even larger-scale parallel computing, with more threads.Originality/valueTo the authors’ knowledge, it is for the first time that the lattice Boltzmann method is applied in the simulation of injection molding, and the proposed model does obviously better in numerical efficiency than the current popular FVM-based models.
Compressive strength analysis of soil reinforced with fiber extracted from water hyacinthVardhan, Harsha; Bordoloi, Sanandam; Garg, Akhil; Garg, Ankit; S., Sreedeep
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-09-2015-0267
PurposeThe purpose of this study is to measure the effects of density, moisture, fiber content on unconfined compressive strength (UCS) of soil by formulating the models based on evolutionary approach and artificial neural networks (ANN).Design/methodology/approachThe present work proposes evolutionary approach of multi-gene genetic programming (MGGP) to formulate the functional relationships between UCS of reinforced soil and four inputs (soil moisture, soil density, fiber content and unreinforced soil strength) of the silty sand. The hidden non-linear relationships between UCS of reinforced soil and the four inputs are determined by sensitivity and parametric analysis of the MGGP model.FindingsThe performance of MGGP is compared to those of ANN and the statistical analysis indicates that the MGGP model is the best and is able to generalize the UCS of reinforced soil satisfactorily beyond the given input range.Research limitations/implicationsThe explicit MGGP model will be useful to provide optimum input values for design and analysis of various geotechnical infrastructures. In addition, utilization of Water hyacinth reinforced fiber reinforced soil will minimize negative impact of this species on environment and may generate rural employment.Originality/valueThis work is first of its kind in application and development of explicit holistic model for evaluating the compressive strength of heterogeneous soil blinded with fiber content. This includes the experimental and cross-validation for testing robustness of the model.
Analysis of repetitive and near-repetitive structures by transformation to equivalent circulant structuresKaveh, A.; Rahami, H.; Jodaki, A.
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-01-2016-0032
PurposeThere are many structures that have a repetitive pattern. If a relationship can be established between a repetitive structure and a circulant structure, then the repetitive structure can be analyzed by using the properties of the corresponding circulant structure. The purpose of this paper is to develop such a transformation.Design/methodology/approachA circulant matrix has certain properties that can be used to reduce the complexity of the analysis. In this paper, repetitive and near-repetitive structures are transformed to circulant structures by adding and/or eliminating some elements of the structure. Numerical examples are provided to show the efficiency of the present method.FindingsA transformation is established between a repetitive structure and a circulant structure, and the analysis of the repetitive structure is performed by using the properties of the corresponding circulant structure.Originality/valueRepetitive and near-repetitive structures are transformed to circulant structures, and the complexity of the analysis of the former structures is reduced by analyzing the latter structures.
Numerical simulation of the blade channel vortices in a Francis turbine runnerZhou, Lingjiu; Liu, Meng; Wang, Zhengwei; Liu, Demin; Zhao, Yongzhi
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-10-2015-0302
PurposeThis study analyzes the blade channel vortices inside Francis runner with a particular focus on the identification of different types of vortices and their causes.Design/methodology/approachA single-flow passage of the Francis runner with refined mesh and periodic boundary conditions was used for the numerical simulation to reduce the computational resource. The steady-state Reynolds-averaged Navier–Stokes equations closed with the k-ω shear–stress transport (SST) turbulence model were solved by ANSYS CFX to determine the flow field. The vortices were identified by the second largest eigenvalue of velocity.FindingsFour types of vortices were identified inside the runner. Three types were related to the inlet flow. The last one (Type 4) was caused by the reversed flow near the runner crown and had the lowest pressure inside the core near the runner outlet. Thus, in the blade channel vortex inception line, Type 4 vortex would appear earlier than the other three ones. Besides, the Type 4 vortex emerged from the crown and shed toward the blade-trailing edge. And its location moved from near the crown down to near the band when the unit speed increased or unit discharge decreased.Research limitations/implicationsAlthough the refined mesh was used and the main vortices in the Francis runner were well predicted, the current mesh is not enough to accurately predict the lowest pressure in the channel vortex core.Practical/implicationsThis knowledge is instructive in the runner blade design and troubleshooting related to the channel vortex.Originality/valueThis study gives an overview of the main observed blade channel vortices and their causes, and points out the important role the reversed flow plays in the formation of blade channel vortices. This knowledge is instructive in the runner blade design and troubleshooting related to blade channel vortices.
Isogeometric analysis of free vibration of framed structures: comparative problemsRauen, Mateus; Machado, Roberto Dalledone; Arndt, Marcos
2017 Engineering Computations: International Journal for Computer-Aided Engineering and Software
doi: 10.1108/EC-08-2015-0227
PurposeThe purpose of this paper is to check the efficiency of isogeometric analysis (IGA) by comparing its results with classical finite element method (FEM), generalized finite element method (GFEM) and other enriched versions of FEM through numerical examples of free vibration problems.Design/methodology/approachSince its conception, IGA was widely applied in several problems. In this paper, IGA is applied for free vibration of elastic rods, beams and trusses. The results are compared with FEM, GFEM and the enriched methods, concerning frequency spectra and convergence rates.FindingsThe results show advantages of IGA over FEM and GFEM in the frequency error spectra, mostly in the higher frequencies.Originality/valueIsogeometric analysis shows a feasible tool in structural analysis, with emphasis for problems that requires a high amount of vibration modes.