Browsing by Author "Latifi Rostami, Seyyed Ali"

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    Design and promotion of cost-effective IOT-based heart rate monitoring
    (SPIE, 2022-07-28) Moshayedi, Ata jahangir; Kolahdooz, Amin; Roy, Atanu Shuvam; Latifi Rostami, Seyyed Ali; Xie, Xiaoyun
    The term telemedicine was first used in the 1920s, although used many years ago and has continued to evolve today. Medical diagnoses usually require visual information, but remote display systems have recently become a special place due to the constant unavailability of the treating physician or the remoteness of medical centers and the constant need of some patients for round-the-clock care. In this article, an Arduino-based heart rate information system is designed and implemented. Due to the reasonable price and easy accessibility of the created system in the fraction, it has many applications. The results of the designed system showed the system's capabilities to track and know the person's heart rate
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    Multi-Objective Parameter Optimization to Improve Machining Performance on Deep Drilling Process
    (Inderscience, 2022-02-22) Damavandi, Esmaeil; Kolahdooz, Amin; Shokoohi, Yousef; Latifi Rostami, Seyyed Ali; Tabatabaei, Sayed Mohamadbagher
    Cutting parameters and factors should be selected wisely to increase the quality of a product. Therefore, the optimisation of the deep drilling process was investigated by utilising the Taguchi method on three materials by three different tools. The influences of cutting speed and workpiece temperature are investigated on machining power, surface roughness and tool wear. The results revealed that the application of preheating could provide lower power consumption and a relatively good finished surface. In continuation, analysis of variance demonstrated that all factors are effective, but the workpiece material and speed are the most influential parameters on surface roughness and power consumption, respectively. Workpiece material influenced about 72.24% on machining performance, and its effect was more than tool material (3.64%). For machining power, the effect of speed (55.41%) was higher than others. The preheating and lower speeds reduced tool wear of titanium coated and cobalt coated drills.
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    Robust Topology Optimization of Continuum Structures under the Hybrid Uncertainties: A Comparative Study
    (Periodica Polytechnica Civil Engineering, 2023-03-28) Latifi Rostami, Seyyed Ali; Li, Muxi; Kolahdooz, Amin; Chung, Hayoung; Zhang, Jian
    Due to the inevitable involvement of multisource uncertainties related to the load, material property and geometry in practical engineering designs, robust topology optimization (RTO) has recently attracted increasing attention to account for these uncertain effects. However, the majority of the existing RTO works are concerned with single source uncertainty, and very few studies have considered the multisource (hybrid) uncertainties simultaneously. To this end, a comparative study on the hybrid uncertainties (HU), i.e., material-loading, geometric-loading, material-geometric, and material-geometric-loading uncertainties, for RTO of continuum structures is presented in this paper. A truncated Karhunen-Loeve expansion is adopted for uncertainty representation and a sparse grid collocation method for uncertainty propagation of the objective function and constraints. Effects of the various HU on the compliance and robust design are comprehensively investigated and compared with the RTO models under individual component uncertainty using two continuum benchmarks. An important observation from the results is that the hybrid uncertainty model is a conservative state, and the resulting RTO designs tend towards those with loading uncertainty only.
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    Robust topology optimization of continuum structures with smooth boundaries using moving morphable components
    (Springer, 2023-05-10) Latifi Rostami, Seyyed Ali; Kolahdooz, Amin; Chung, Hayoung; Shi, Maolin; Zhang, Jian
    Topology optimization has been increasingly used in various industrial designs as a numerical tool to optimize the material layout of a structure. However, conventional topology optimization approaches implicitly describe the structural design and require additional post-processing to generate a manufacturable topology with smooth boundaries. To this end, this paper proposes a novel robust topology optimization approach to produce an optimized topology with smooth boundaries directly. A truncated Karhunen–Loeve expansion and a sparse grid collocation method are integrated with the explicit moving morphable components method for uncertainty representation and propagation, respectively. The performance of the proposed method is assessed on three numerical examples of continuum structures under loading and material uncertainties through comparison with several robust topology optimization approaches. Results show that the proposed method is superior to the benchmark methods in terms of the balance among robustness of the objective function, boundary smoothness, and computational efficiency.
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    Robust topology optimization under material and loading uncertainties using an evolutionary structural extended finite element method
    (Elsevier, 2021-09-01) Latifi Rostami, Seyyed Ali; Kolahdooz, Amin; Zhang, Jian
    This research presents a novel algorithm for robust topology optimization of continuous structures under material and loading uncertainties by combining an evolutionary structural optimization (ESO) method with an extended finite element method (XFEM). Conventional topology optimization approaches (e.g. ESO) often require additional post-processing to generate a manufacturable topology with smooth boundaries. By adopting the XFEM for boundary representation in the finite element (FE) framework, the proposed method eliminates this time-consuming post-processing stage and produces more accurate evaluation of the elements along the design boundary for ESO-based topology optimization methods. A truncated Gaussian random field (without negative values) using a memory-less translation process is utilized for the random uncertainty analysis of the material property and load angle distribution. The superiority of the proposed method over Monte Carlo, solid isotropic material with penalization (SIMP) and polynomial chaos expansion (PCE) using classical finite element method (FEM) is demonstrated via two practical examples with compliances in material uncertainty and loading uncertainty improved by approximately 11% and 10%, respectively. The novelty of the present method lies in the following two aspects: (1) this paper is among the first to use the XFEM in studying the robust topology optimization under uncertainty; (2) due to the adopted XFEM for boundary elements in the FE framework, there is no need for any post-processing techniques. The effectiveness of this method is justified by the clear and smooth boundaries obtained.
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    Topology optimization of continuum structures under geometric uncertainty using a new extended finite element method
    (Taylor & Francis, 2021-08-31) Latifi Rostami, Seyyed Ali; Ghoddosian, Ali; Kolahdooz, Amin; Zhang, Jian
    In this article, robust topology optimization under geometric uncertainty is proposed. The design domain is discretized by an extended finite element method. A bi-directional evolutionary structural optimization carries out the optimization process. The performance of the proposed method is compared with the Monte Carlo, solid isotropic material with penalization, perturbation and non-intrusive polynomial chaos expansion methods. The novelty of the present method lies in the following three aspects: (1) this article is among the first to use the extended finite element method in studying the topology optimization under uncertainty; (2) by adopting the extended finite element method for boundary elements in the finite element framework, there is no need for any remeshing techniques; and (3) the numerical results show that the present method has a smoother boundary region and minimum value of the mean and standard deviation of compliance than the other methods, in particular mesh size.