Hasil untuk "Mechanics of engineering. Applied mechanics"

Mansoor Ahmad, Mohamad Sawan

Microelectromechanical systems (MEMS) micromirrors have become vital components in biomedical applications, driving advances in minimally invasive diagnostics and targeted therapies. We provide in this review of MEMS micromirrors focusing on their performance, utility, and adaptability in key imaging and therapeutic modalities. MEMS micromirrors, known for precise and high-speed beam control, are integral to devices such as optical coherence tomography (OCT), photoacoustic imaging, confocal and multiphoton endomicroscopy, and optogenetics. In OCT and photoacoustic imaging, they enhance resolution for early disease detection. In confocal and multiphoton endomicroscopy, they enable real-time, high-resolution cellular imaging. Optogenetics benefits from their targeted light delivery for neural modulation and therapy. While briefly outlining primary actuation mechanisms, the review emphasizes biomedical applications. By focusing on key performance aspects and real-world use cases, this article offers insights into how MEMS micromirrors are shaping next-generation biomedical devices and advancing diagnostic and therapeutic technologies.

Eduard Enoiu, Jean Malm, Gregory Gay

We explore the concept of folklore within software engineering, drawing from folklore studies to define and characterize narratives, myths, rituals, humor, and informal knowledge that circulate within software development communities. Using a literature review and thematic analysis, we curated exemplar folklore items (e.g., beliefs about where defects occur, the 10x developer legend, and technical debt). We analyzed their narrative form, symbolic meaning, occupational relevance, and links to knowledge areas in software engineering. To ground these concepts in practice, we conducted semi-structured interviews with 12 industrial practitioners in Sweden to explore how such narratives are recognized or transmitted within their daily work and how they affect it. Synthesizing these results, we propose a working definition of software engineering folklore as informally transmitted, traditional, and emergent narratives and heuristics enacted within occupational folk groups that shape identity, values, and collective knowledge. We argue that making the concept of software engineering folklore explicit provides a foundation for subsequent ethnography and folklore studies and for reflective practice that can preserve context-effective heuristics while challenging unhelpful folklore.

Fumiya KIDENA, Kenya KITADA, Yuichiro ISHII et al.

This study investigates the puffing-induced secondary atomization and evaporation behavior of a bi-component droplet composed of miscible species (n-heptane and n-hexadecane) using three-dimensional numerical simulations. The gas–liquid interface is captured using the coupled level-set and volume of fluid (CLSVOF) method, and evaporation of two components is modeled based on a non-ideal vapor–liquid equilibrium (VLE) formulation. The simulation consists of two stages: a stationary stage to establish initial thermal and concentration fields assuming a quiescent droplet, and a puffing stage where a vapor bubble of n-heptane is initially embedded within the droplet. The results qualitatively reproduce the fundamental dynamics of puffing droplets, including bubble growth, burst, vapor ejection, ligament formation, and its fragmentation as reported in previous experimental and numerical studies. The analysis reveals a strong dependence of the evaporation behavior on the embedded bubble positioning. While n-heptane shows a sharp decline in evaporation rate after bubble bursts, evaporation rate of n-hexadecane exhibits a transient enhancement owing to rapid redistribution over the droplet surface. Furthermore, placing the bubble deeper inside the droplet leads to stronger puffing and sustains fuel, especially n-heptane, evaporation, highlighting the critical role of internal distribution of species and bubble positioning in bi-component droplet evaporation under puffing conditions.

Qi-Yu Hu, Ze-Qi Lu, Jian-hua Zhang et al.

Abstract Magnetic levitation planar motors (MLPMs) exhibit significant potential in high-precision positioning applications, however the 6-degree-of-freedom (6-DOF) control performance is inherently limited by complex nonlinear dynamics. This paper proposes a 6-DOF dynamic modeling methodology for maglev planar motors based on reference trajectory tracking. The proposed approach synergistically combines magnetic flux analytical linearization with electromagnetic coupling field decoupling, establishing a unified control framework that comprehensively addresses kinematic nonlinearities and full-DOF coupling effects. By employing harmonic spectral analysis and a dual-reference coordinate transformation architecture, the method enables precise analytical derivation of electromagnetic force/torque distributions within the operational workspace. Numerical simulations validate the improved modeling accuracy, demonstrating a 5.3-fold reduction in wrench prediction errors under large yaw rotations compared to conventional methods. Finally, an experimental rig of the planar motor is manufactured to validate the theoretical trajectory tracking method. The experimental results confirm the robustness of the methodology in achieving high-precision motion control and long-stroke trajectory tracking, offering valuable insights for bridging theoretical modeling and industrial implementation of maglev planar motor systems.

Kim Sharp

In statistical mechanics the zeroth law of thermodynamics is taken as a postulate which, as its name indicates, logically precedes the first and second laws. Treating it as a postulate has consequences for how temperature is introduced into statistical mechanics and for the molecular interpretation of temperature. One can, however, derive the zeroth law from first principles starting from a classical Hamiltonian using basic mechanics and a geometric representation of the phase space of kinetic energy configurations - the velocity hypersphere. In this approach there is no difficulty in providing a molecular interpretation of temperature, nor in deriving equality of temperature as the condition of thermal equilibrium. The approach to the macroscopic limit as a function of the number of atoms is easily determined. One also obtains with little difficulty the Boltzmann probability distribution, the statistical mechanical definition of entropy and the configuration partition function. These relations, along with the zeroth law, emerge as straightforward consequences of atoms in random motion.

Cesar Patino, Sevketcan Sarikaya, Prithvijit Mukherjee et al.

Efficient and nontoxic delivery of foreign cargo into cells is a critical step in many biological studies and cell engineering workflows with applications in areas such as biomanufacturing and cell-based therapeutics. However, effective molecular delivery into cells involves optimizing several experimental parameters. In the case of electroporation-based intracellular delivery, there is a need to optimize parameters like pulse voltage, duration, buffer type, and cargo concentration for each unique application. Here, we present the protocol for fabricating and utilizing a high-throughput multi-well localized electroporation device (LEPD) assisted by deep learning–based image analysis to enable rapid optimization of experimental parameters for efficient and nontoxic molecular delivery into cells. The LEPD and the optimization workflow presented herein are relevant to both adherent and suspended cell types and different molecular cargo (DNA, RNA, and proteins). The workflow enables multiplexed combinatorial experiments and can be adapted to cell engineering applications requiring in vitro delivery.

Zhicheng He, Zhifu Chen, Guilin Liu et al.

Galactic-wide outflows driven by active galactic nuclei (AGNs) is a routinely invoked feedback mechanism in galaxy evolution models. Hitherto, the interplay among the interstellar gas on galactic scales, the propagation of AGN outflows and the fundamental AGN parameters during evolution remains elusive. Powerful nuclear outflows are found to favorably exist at early AGN stages usually associated with high accretion rates and weak narrow emission lines. In a sample of quasars emitting Mg II narrow absorption lines (NALs) from the Sloan Digital Sky Survey, we discover an unprecedented phenomenon where galaxy-scale inflow-dominated transforming into outflow-dominated gas accompanied by an increasing strength of the narrow [O III] line, at a confidence level of 6.7σ. The fact that nuclear outflows diminish while galaxy-wide outflows intensifies as AGNs evolve implies that early-stage outflows interact with interstellar medium on galactic scales and trigger the gradual transformation into galaxy-wide outflows, providing observational links to the hypothetical multi-stage propagation of AGN outflows that globally regulates galaxy evolution.

E. Becker, U . Brosa, T. A. Kowalewski

We look directly into the phase space of experimental or numerical data to derive nonlinear equations of motion. Our example is the dynamics of viscous droplets. While the smallest useful dimension of phase space turns out to be three, we apply methods to visualize four, five, six dimensions and more. These methods are Poincare sections and condensation of variables. The resulting equations of motion are extremely simple but nevertheless realistic.  

M. Sundar Raj, G. Nagarajan, V. P. Murugan et al.

An accurate parameterization of an irregular surge across a continuously propelled circulation through an endless isothermal inclined plate has been investigated in the presence of a first-degree uniform chemical reaction. Both the plate’s temperature and the proximal intensity are increased systematically. To evaluate non-dimensional equations, the Laplace transform is utilized. The effect of velocity components on a range of physical parameters is investigated which include Sc, Pr, Gr, Gc, α, K and t. A proportionate increase of velocity with Gr and Gc was prominent. τ and Sh were mathematically determined.

Jacek Bauer, Jarosław Latalski

In most cases a safety of optimal construction may be limited by the violation of stress, buckling or displacement constraints. An unexpected exceed of these constraints may be caused by manufacturing tolerances of structural elements (differences between assumed and obtained dimensions). This requires an incorporation of tolerance problem in optimum design. One may deal with two different tolerances – the first case is when it's related to the members' cross-section variations, whereas the second notion represents the variation of elements' lengths. Considering operation conditions and manufacturing techniques the second case of tolerance seems to be more important. This approach states the problem of minimum weight design of a structure with initial distortions. A standard solution algorithm with the Kuhn-Tucker theorem was used with the adjoint variable method. Necessary optimality conditions have the form of equations and inequalities. The equality constraints were put forward for the average values of design variables l, while tolerances tj were introduced into inequality equations i.e. the limit values of stresses and displacements were diminished by the positive products of appropriate sensitivities and tolerances. The method was next illustrated by an example of a ten bar bench-mark problem - a typical one for testing algorithms in structural optimization. The idea presented in this paper may be used not only for truss structures but it can be easily extended to other kinds of structures like frames, composites etc.

Manish Srivastava, Jeeoot Singh

Radial basis functions (RBFs) with modified radial distance are proposed for vibration analysis of functionally graded materials (FGM) rectangular plates. The displacement field with five variables higher-order shear deformation theory (HSDT) is considered. The governing differential equations (GDEs) and boundary conditions are obtained using Hamilton's principle. The governing differential equations formulations are solved via strong-form solutions. The rectangular plates are analyzed in the framework of the RBF-based meshfree method. The novelty of the present modified method is to analyze the square and rectangular plates without changing the shape parameters. Here, the seventeen different RBFs are available in various literature to demonstrate the accuracy and efficiency of the present method in terms of the number of nodes and computational time. The results of several numerical examples have shown that the present modified RBF-based mesh-free method can lead to much more accurate solutions. Computational times of different RBFs are also analyzed.

Midas Segers, Aderik Voorspoels, Takahiro Sakaue et al.

Proteins often regulate their activities via allostery - or action at a distance - in which the binding of a ligand at one binding site influences the affinity for another ligand at a distal site. Although less studied than in proteins, allosteric effects have been observed in experiments with DNA as well. In these experiments two or more proteins bind at distinct DNA sites and interact indirectly with each other, via a mechanism mediated by the linker DNA molecule. We develop a mechanical model of DNA/protein interactions which predicts three distinct mechanisms of allostery. Two of these involve an enthalpy-mediated allostery, while a third mechanism is entropy driven. We analyze experiments of DNA allostery and highlight the distinctive signatures allowing one to identify which of the proposed mechanisms best fits the data.

Huajie Dai, Huajie Dai, Xueting Zhang et al.

Acoustic metamaterials, artificial composite structures with exotic material properties used to control elastic waves, have become a new frontier in physics, materials science, engineering and chemistry. In this paper, the research progress and development prospect of acoustic metamaterials are reviewed. Related studies on passive acoustic metamaterials and active acoustic metamaterials are introduced and compared. Additionally, we discuss approaches to material structure design, including topology optimization approaches, as well as bio-inspired and fractal geometry-based approaches to structure design. Finally, we summarize and look forward to the prospects and directions of acoustic metamaterial research. With the development of additive manufacturing technology, the research potential of acoustic metamaterials is huge.

Rehman Shafiqur, Sahin Ahmet Z., Al-Sulaiman Fahad A.

In the present work, solar water heating systems having nominal water usage of 24 cubic meters per day are considered. To identify the better option, both technologically and economically, a typical geographical location in Saudi Arabia, namely Abha, is considered. Internal rate of return (IRR) values for the solar collectors with glazing are found to be higher as compared with that of the unglazed type. The glazed type collectors are found to be more efficient, provide greater savings in fuel consumption, and result in the reduction of greenhouse gas (GHG) emissions. The findings of this study can be used for locations with similar types of climatic conditions in any part of the world.

S. Arulmozhi, K. Sukkiramathi, S.S. Santra et al.

A comparative study of nanofluid (Cu–H2O) and pure fluid (water) is investigated over a moving upright plate surrounded by a porous surface. The novelty of the study includes the unsteady laminar MHD natural transmission flow of an incompressible fluid, to get thermal conductivity of nanofluid is more than pure fluid. The chemical reaction of this nanofluid with respect to radiation absorption is observed by considering the nanoparticles to attain thermal equilibrium. The present work is validated with the previously published work. The upright plate travels with a constant velocity u0, and the temperature and concentration are considered to be period harmonically independent with a constant mean at the plate. The most excellent appropriate solution to the oscillatory pattern of boundary layer equations for the governing flow is computed utilizing the Perturbation Technique. The impacts of factors on velocity, temperature, and concentration are visually depicted and thoroughly elucidated. The fluid features in the boundary layer regime are explored visually and qualitatively. This enhancement is notably significant for copper nanoparticles.

Elhefnawy Ahmed, Elmaihy Ali, Elweteedy Ahmed

This work includes the thermal control analysis of a small spacecraft in the post-mission phase. The satellite internal component distribution has been modified to fulfill all thermal requirements when using a passive thermal control system. In the post-mission phase, the satellite will be used by the radio Amateur Satellite Corporation (AMSAT) community as a transponder, fully using the AMSAT payload that will maintain active and shall last at least 2 years. Thermal Desktop software is introduced for the mentioned spacecraft. The final analysis predictions show that the passive thermal control system maintains all satellite element's temperatures within their temperature limits. The temperature variation of +X solar panel is 75 °C which is less than experienced by +Z and -Z panels, which are 100 °C. The temperature change on equipment agrees with their panels. Compared with a specialized thermal analysis, software package (ESATAN-TMSs) verified the integrity of the results.

Pham Van Vinh

In this paper, the static bending behavior of the functionally graded sandwich beams is investigated using a novel mixed beam element based on the first-order shear deformation theory. The proposed beam element consists of two nodes and three degrees of freedom per node as the traditional Timoshenko beam element. By introducing a special process, selective or reduced integration are not required to calculate the element stiffness matrix and nodal force vector. The efficiency and accuracy of the proposed element are verified via some comparison studies. Then the proposed element is applied to study the bending behavior of the functionally graded sandwich beams with various boundary conditions. The influences of some parameters such as the power-law index, the slender ratio and the boundary conditions are studied carefully. The comparison studies and numerical results present that the new beam element is compatible with the static bending analysis of the functionally graded sandwich beams with a very coarse mesh. Besides, the numerical results show that the stress concentration may occur on the separated surface of the core layer and two face sheets, which should be noticed in practical applications of the FG sandwich beams.

R. M. Jena, S. Chakraverty, D. Baleanu

Abstract Nonlinear fractional differential equations (NFDEs) offer an effective model of numerous phenomena in applied sciences such as ocean engineering, fluid mechanics, quantum mechanics, plasma physics, nonlinear optics. Some studies in control theory, biology, economy, and electrodynamics, etc. demonstrate that NFDEs play the primary role in explaining various phenomena arising in real-life. Now-a-day NFDEs in various scientific fields in particular optical fibers, chemical physics, solid-state physics, and so forth have the most important subjects for study. Finding exact responses to these equations will help us to a better understanding of our environmental nonlinear physical phenomena. In this regard, in the present study, we have applied fractional reduced differential transform method (FRDTM) to obtain the solution of nonlinear time-fractional Hirota-Satsuma coupled KdV and MKdV equations. The novelty of the FRDTM is that it does not require any discretization, transformation, perturbation, or any restrictive conditions. Moreover, this method requires less computation compared to other methods. Computed results are compared with the existing results for the special cases of integer order. The present results are in good agreement with the existing solutions. Here, the fractional derivatives are considered in the Caputo sense. The presented method is a semi-analytical method based on the generalized Taylor series expansion and yields an analytical solution in the form of a polynomial.

N. Elgazery

Tobias Gulden, Alex Kamenev

We study dynamics and thermodynamics of ion channels, considered as effective 1D Coulomb systems. The long range nature of the inter-ion interactions comes about due to the dielectric constants mismatch between the water and lipids, confining the electric filed to stay mostly within the water-filled channel. Statistical mechanics of such Coulomb systems is dominated by entropic effects which may be accurately accounted for by mapping onto an effective quantum mechanics. In presence of multivalent ions the corresponding quantum mechanics appears to be non-Hermitian. In this review we discuss a framework for semiclassical calculations for corresponding non-Hermitian Hamiltonians. Non-Hermiticity elevates WKB action integrals from the real line to closed cycles on a complex Riemann surfaces where direct calculations are not attainable. We circumvent this issue by applying tools from algebraic topology, such as the Picard-Fuchs equation. We discuss how its solutions relate to the thermodynamics and correlation functions of multivalent solutions within long water-filled channels.