ME Research Publications

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    The Importance of Safety for Manufacturing Nanomaterials
    (De Gruyter, 2024) Khan, Waseem Sabir; Asmatulu, Ramazan
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    The World of Engineering Nanomaterials
    (De Gruyter, 2024) Asmatulu, Eylem
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    Synthesis, crystal and electronic structures, linear and nonlinear optical properties, and photocurrent response of oxyhalides CeHaVIO$_4$ (Ha = Cl, Br; VI = Mo, W)
    (Royal Society of Chemistry, 2023-12) Jiao, Zixian; Quah, Jasmine; Syed, Tajamul Hussain; Wei, Wei; Zhang, Bingbing; Wang, Fei; Wang, Jian
    Four heteroanionic oxyhalides, CeClMoO$_4$, CeBrMoO$_4$, CeClWO$_4$, and CeBrWO$_4$, have been studied as multifunctional materials, which show a combination of good second harmonic generation (SHG) response and photocurrent signals. Millimeter-sized CeHaVIO$_4$ (Ha = Cl, Br; VI = Mo, W) crystals were grown by halide salt flux. The crystal structure of CeHaVIO$_4$ crystals was accurately determined by single-crystal X-ray diffraction. CeClMoO$_4$, CeBrMoO$_4$, and CeBrWO$_4$ are isostructural to each other, and crystallize in the acentric LaBrMoO4 structure type. CeClWO$_4$ crystallizes in a new structure type with unit cell parameters of $a$ = 19.6059(2) Å, $b$ = 5.89450(10) Å, $c$ = 7.80090(10) Å, and β = 101.4746(8)°. The bandgaps of CeHaVIO$_4$ fall into the range of 2.8(1)-3.1(1) eV, which are much smaller than those of isotypic LaHaVIO$_4$ (Ha = Cl, Br; VI = Mo, W) in the range of 3.9(1)-4.3(1) eV. The narrowing of bandgaps in CeHaVIO$_4$ originates from the presence of partially filled 4f orbitals of cerium atoms, which was confirmed by density functional theory (DFT) calculations. The moderate bandgaps make CeHaVIO$_4$ suitable for infrared nonlinear optical (IR NLO) applications. CeBrMoO$_4$ and CeBrWO$_4$ exhibit moderate SHG responses of 0.58x AGS and 0.46x AGS, respectively, and are both type-I phase-matching materials. Moderate SHG response, easy growth of crystals, high ambient stability, and type-I phase-matching behavior make CeBrMoO$_4$ and CeBrWO$_4$ great materials for IR NLO applications. CeHaVIO$_4$ films also exhibited good photocurrent response upon light radiation. This work demonstrates the rich structural chemistry of the REHaVIO$_4$ (RE = Y, La-Lu; Ha = Cl, Br; VI = Mo, W) family and the potential presence of more multifunctional materials.
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    Analytical Modeling of A 3-Phase Nanocomposite Cylindrical Unit Cell with Orthotropic Constituents
    (SAMPE, 2023-10-30) Sritharan, Ramanan; Askari, Davood
    In this study, closed-form analytical solutions were developed to predict the effective transverse Young’s modulus, Poisson’s ratios, and mechanical responses of a 3-phase nanocomposite cylindrical model, representing a nanocomposite unit cell, subjected to uniform external pressure. The model is composed of three concentric tubes with distinct generally cylindrical orthotropic properties, representing a carbon nanotube (CNT) surrounded by a matrix and a distinct interphase region in between them. To verify the analytically derived solutions, the unit check was performed at every stage of the formula development and the units for the final solutions were all consistent and verified. For further verification, three different sets of orthotropic materials properties and dimensions were assigned to the constituents and numerical values were obtained for the effective material properties that agreed with our expectations. Furthermore, a uniform external pressure was applied to the outside boundary of the three-phase nanocomposite tube to investigate and verify the mechanical responses (e.g., radial displacements and axial stresses) of the nanocomposite unit cell model. To demonstrate the applicability of the analytical solutions for parametric studies, design analysis, and optimization, one can investigate the variation of the effective transverse Young’s modulus as a function of the constituents’ volume contents and study the stress and strain distributions.
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    Chaotic Motion Planning for Mobile Robots: Progress, Challenges, and Opportunities
    (Institute of Electrical and Electronics Engineers Inc., 2023-11) Ahuraka, Farida; McNamee, Patrick; Wang, Qixu; Ahmadabadi, Zahra N.; Hudack, Jeffrey
    Chaotic path planners are a subset of path planning algorithms that use chaotic dynamical systems to generate trajectories throughout an environment. These path planners are imperative in surveillance tasks in the presence of adversarial agents which require the paths to be unpredictable while at the same time guaranteeing complete coverage of the environments. In the online coverage of unknown terrain, the chaotic path planning algorithms can work without the need of the environment map and the designer has additional control over the generated paths relative to other heuristic coverage path planners such as random-walk algorithms. Although chaotic path planners have been studied over the past two decades, there has not been an updated survey on the advances. This paper presents an up-to-date review by providing: an introduction of commonly used chaotic systems and methods for their manipulation; an overview of obstacle avoidance methods used by chaotic path planners; and a discussion on other applications, challenges, and research gaps.