Hasil untuk "Mechanics of engineering. Applied mechanics"

Šimon Berta, Vladimír Goga, Kristián Ondrejička et al.

This paper outlines the design, development, and practical implementation of a rubber belt-driven dual cone continuously variable transmission (CVT) model. This model enables a demonstration of stepless changes in the transmission ratio between input and output shafts. Although the model can be operated manually via a control panel, enhanced functionality, such as automated measurement, proportional-integral-derivative (PID) speed control, and data measurement and storage, is achieved through a control application created within the LabVIEW virtual instrument environment. This work also includes a partial comparison between the practical implementation and its simulation model created in MATLAB-Simulink.

Cláudio Lúcio do Val Lopes, João Marcus Pitta, Fabiano Belém et al.

The integration of Artificial Intelligence (AI) into clinical settings presents a software engineering challenge, demanding a shift from isolated models to robust, governable, and reliable systems. However, brittle, prototype-derived architectures often plague industrial applications and a lack of systemic oversight, creating a ``responsibility vacuum'' where safety and accountability are compromised. This paper presents an industry case study of the ``Maria'' platform, a production-grade AI system in primary healthcare that addresses this gap. Our central hypothesis is that trustworthy clinical AI is achieved through the holistic integration of four foundational engineering pillars. We present a synergistic architecture that combines Clean Architecture for maintainability with an Event-driven architecture for resilience and auditability. We introduce the Agent as the primary unit of modularity, each possessing its own autonomous MLOps lifecycle. Finally, we show how a Human-in-the-Loop governance model is technically integrated not merely as a safety check, but as a critical, event-driven data source for continuous improvement. We present the platform as a reference architecture, offering practical lessons for engineers building maintainable, scalable, and accountable AI-enabled systems in high-stakes domains.

Jinlong Zhang, Weijian Liu, Yuhong Dong

Abstract Accurate prediction of air‐sea fluxes hinges on a deep understanding of wind‐wave interactions, yet feedback mechanisms involving surface waves and wind are not fully understood. This paper investigates the effect of two‐way coupling between wind and waves on wind turbulence through direct numerical simulation of air‐water two‐phase flows, with simulations of non‐coupling cases for wind sea and swell. Compared to the uncoupled model, the dissipation of surface waves absorbs momentum from the wind for a wind sea, reducing turbulence intensity, which decreases momentum and heat transfer coefficients (CD and CH). In a swell scenario, a wave‐driven wind jet produces strong shear and changes interfacial dynamics under coupled conditions, enhancing turbulence intensity within the wave boundary layer. Air‐water interaction fosters a positive feedback loop between wind and swells, leading to a consequent increase in CD and CH. Parameterizations of CD and CH need to account for the wind‐wave coupling.

Saifudden Saif, Hossein Hosseinzadeh, Zeinab Sedaghatjoo

The purpose of this note is to address an error in the paper titled “A Radial Basis Function Collocation Method for Space-dependent Inverse Heat Problems,” published in the Journal of Applied and Computational Mechanics, 6, 2020, 1187-1199, which affects the numerical results presented therein. Consequently, we propose a numerical scheme to solve the inverse heat problem using the Radial Basis Functions Collocation Method. Then the paper is modified by this note.

James R. Jowsey, G. Gregory Haff, Paul Comfort et al.

Background: CrossFit^® aims to be equitable between both males and female athletes, supporting equal representation and equal prize money at international events. However, to date, limited information is known on CrossFit^® athletes’ performance in the countermovement jump (CMJ), countermovement rebound jump (CMR-J), and isometric mid-thigh pull (IMTP) when assessed using force plates, and if there are any differences between sexes. Therefore, the purpose of the present study was to observe whether any sex-based differences and relationships exist between performance within these assessments. Methods: A total of CrossFit athletes (43 male = 32.8 ± 9.0 years; height 1.78 ± 0.06 m; mass = 92.4 ± 10.6 kg; and 31 female = 31.0 ± 7.6 years, height = 1.64 ± 0.05 m; mass = 68.8 ± 6.0 kg) completed three trials of CMJ, CMR-J and IMTP using portable dual-system force-plate sampling at 1000 Hz. Results: Moderate–large relationships were observed between CMJ, CMR-J and IMTP outcome measures (<i>r</i> = 0.396–0.809, <i>p</i> < 0.001). Males demonstrated small to moderately greater performance outcomes than females for CMJ height (males = 0.35 ± 0.08 m; females 0.30 ± 0.06 m, <i>d</i> = 0.73), CMR-J height (males = 0.32 ± 0.08 m; females = 0.30 ± 0.06 m, <i>d</i> = 0.39) and IMTP peak net force (males = 30.62 ± 10.01 N·kg⁻¹; females = 27.49 ± 6.44 N·kg⁻¹, <i>d</i> = 0.29). Conclusions: Maximal relative strength in CrossFit^® athletes should be seen as imperative in both male and female athletes due to the meaningful relationship in ballistic and plyometric ability. Moreover, previous relationships with CrossFit^® performance and the injury risk reduction benefits of improving strength provide further support. The descriptive data presented could be used by CrossFit^® coaches to assess and compare the current performance of their own athletes in a battery of tests examining CMJ, CMR-J and IMTP, while also facilitating decisions upon prescription within training and competition.

Marina Araújo, Júlia Araújo, Romeu Oliveira et al.

[Context] Domain knowledge is recognized as a key component for the success of Requirements Engineering (RE), as it provides the conceptual support needed to understand the system context, ensure alignment with stakeholder needs, and reduce ambiguity in requirements specification. Despite its relevance, the scientific literature still lacks a systematic consolidation of how domain knowledge can be effectively used and operationalized in RE. [Goal] This paper addresses this gap by offering a comprehensive overview of existing contributions, including methods, techniques, and tools to incorporate domain knowledge into RE practices. [Method] We conducted a systematic mapping study using a hybrid search strategy that combines database searches with iterative backward and forward snowballing. [Results] In total, we found 75 papers that met our inclusion criteria. The analysis highlights the main types of requirements addressed, the most frequently considered quality attributes, and recurring challenges in the formalization, acquisition, and long-term maintenance of domain knowledge. The results provide support for researchers and practitioners in identifying established approaches and unresolved issues. The study also outlines promising directions for future research, emphasizing the development of scalable, automated, and sustainable solutions to integrate domain knowledge into RE processes. [Conclusion] The study contributes by providing a comprehensive overview that helps to build a conceptual and methodological foundation for knowledge-driven requirements engineering.

Nupoor Thakur, Navinder Singh

Quantum mechanics broadly classifies the particles into two categories: $(1)$ fermions and $(2)$ bosons. Fermions are half-integer spin particles, obeying Pauli's exclusion principle and Fermi-Dirac statistics. Whereas bosons are integer spin particles, not obeying Pauli's exclusion principle, and obeying Bose-Einstein statistics. However, there are two exceptions to this standard case: first, anyons, which exist in 2-dimensional systems, and secondly, paraparticles, which can exist in any dimension. Paraparticles follow their non-trivial parastatistics, obeying their generalised exclusion principle. In this paper, we provide a detailed review of the foundations of paraparticle statistics established in \cite{wang2025particle}. We extend this work further and then derive an important expression for the heat capacity of paraparticles for a specific case, which would provide a handle for the experimental detection of paraparticles in appropriate systems.

K. Uddin, Hai Anh Nguyen, T. Nguyen et al.

Midsoles are important components in footwear as they provide shock absorption and stability, thereby improving comfort and effectively preventing certain foot and ankle injuries. A rationally tailored midsole can potentially mitigate plantar pressure, improving performance and comfort levels. Despite the importance of midsole design, the potential of using in-plane density gradation in midsole has been rarely explored in earlier studies. The present work investigates the effectiveness of in-plane density gradation in shoe midsoles using a new class of polyurea foams as the material candidate. Their excellent cushioning properties justify the use of polyurea foams. Different polyurea foam densities, ranging from 95 to 350 kg/m3 are examined and tested to construct density-dependent correlative mathematical relations required for the optimization process. An optimization framework is then created to allocate foam densities at certain plantar zones based on the required cushioning performance constrained by the local pressures. The interior-point algorithm was used to solve the constrained optimization problem. The optimization algorithm introduces a novel approach, utilizing the maximum specific energy absorption as the objective function. The optimization process identifies specific foam densities at various plantar regions for maximum biomechanical energy dissipation without incurring additional weight penalties. Our results suggest midsole design can benefit from horizontal (in-plane) density gradation, leading to potential weight reduction and localized cushioning improvements. With local plantar peak pressure data analysis, the optimization results indicate low-density polyurea foams (140 kg/m3) for central and lateral phalanges, whereas stiffer foams (185-230 kg/m3) are identified as suitable candidates for metatarsal and arch regions in an in-plane density graded midsole design.

Safril Safril, Wan Hamzah Azmi, Nurul Nadia Mohd Zawawi et al.

Tribological properties are crucial for air-conditioning system performance. The properties can be improved using nanolubricant. However, the effect of the binary ratio of hybrid nanolubricants on the tribological performance of automotive systems is limited in the literature. Therefore, the present study investigates the tribology performance of TiO2-SiO2 nanolubricants for application in automotive air-conditioning (AAC) systems. The dispersion of TiO2 and SiO2 into PVE lubricant was carried out using a two-step method. Subsequently, the dispersion stability was assessed qualitatively and quantitatively. The samples were characterised by a volume concentration of 0.010%, with variations in the mixture ratio of 20:80, 40:60, 50:50, 60:40, and 80:20. Coefficient of friction (COF) and wear scar diameter (WSD) values were determined using the Koehler Four-ball Tribo Tester and Light Compound Microscopy. The investigation revealed that each sample experienced a reduction in COF, with the 40:60 ratio demonstrating the best ratio with the most significant decrease of 37.09%. At the same time, the COF decreased by 8.34%, 2.12%, 7.37%, and 15.11% for the nanolubricant samples at 20:80, 50:50, 60:40, and 80:20, respectively. The WSD evaluation showed that the 40:60 ratio has the lowest scar diameter of 0.0344 mm and a 37.09% wear rate decrease compared to pure lubricant. Each sample exhibits superior performance when evaluated for tribological characteristics and performance, particularly in the case of nanolubricants with the 40:60 ratio. The TiO2-SiO2/PVE, characterised by a volume concentration of 0.010%, has remarkable efficacy across different binary ratios, making it highly recommended with a 40:60 ratio for lubricating AAC compressor systems.

Damian Mazur

The results of computations of forces and moments in induction motor made with OPERA 2D program and possibilities of application of FEA methods to consider the failure states during the calculations of induction machine dynamics are discussed in this paper. A mathematics model of an induction motor makes it possible to perform the calculations and analysis of stator currents and electromagnetic torque when the rotor rotates eccentrically, as well as when a bar or rotor ring is broken. A tool has been created which enables to predict preliminarily the results of the defects, which might be introduced at the motor manufacturing stage. To calculate 3D free vibration frequencies of the rotor system of the motor under consideration the PATRAN package has been used. It allowed us to examine the resonance frequencies of the rotor. For the diagnostic measurements the MotorMonitor™ program has been applied. It was possible to attain high computational effectiveness due to parallel programming on CONVEX computers of ACC "CYFRONET".

Shujun Wu, Yujiao Yang, Yao Cheng et al.

Abstract A “turn‐on” fluorescent sensing strategy was developed for ultrasensitive detection of heavy metal mercury ion (Hg2+) directly in water. It utilized an aqueous soluble aggregation‐induced emission (AIE)‐active probe, named 1,1,2,2‐tetrakis(4‐(1H‐tetrazol‐5‐yl)phenyl)ethene (TPE‐4TA), composing of a luminescent tetraphenylene core and multiple anionic tetrazolate spawns. The probe retained dark when molecularly dissolved in water. However, mercury ions can ligate with multiple tetrazolate groups to form infinite coordination polymer particles spontaneously, thus inducing a fluorogenic AIE response for in situ analysis. Moreover, by embedding this AIE sensing molecules in a hydrophilic polyvinyl alcohol substrate, the resulting hydrogel film allowed in situ detection of Hg2+ on a laser‐induced fluorescence analysis setup in aqueous environment. This strategy worked effectively in common aqueous environments with pH from 4 to 7.5 and showed high sensitivity (limit of detection down to 0.38 ppb/1.9 nM), good selectivity and a wide linearity range for quantification. This work may lead to a reliable and promising platform for on‐site environmental water analysis.

Nathan Justus, Rodrigo Krugner, Ross L. Hatton

From courtship rituals, to prey identification, to displays of rivalry, a spider’s web vibrates with a symphony of information. Examining the modality of information being transmitted and how spiders interact with this information could lead to new understanding how spiders perceive the world around them through their webs, and new biological and engineering techniques that leverage this understanding. Spiders interact with their webs through a variety of body motions, including abdominal tremors, bounces, and limb jerks along threads of the web. These signals often create a large enough visual signature that the web vibrations can be analyzed using video vibrometry on high-speed video of the communication exchange. Using video vibrometry to examine these signals has numerous benefits over the conventional method of laser vibrometry, such as the ability to analyze three-dimensional vibrations and the ability to take measurements from anywhere in the web, including directly from the body of the spider itself. In this study, we developed a method of three-dimensional vibration analysis that combines video vibrometry with stereo vision, and verified this method against laser vibrometry on a black widow spiderweb that was experiencing rivalry signals from two female spiders.

Prashant Pandey, Sachin Kumar, J.F. Gómez-Aguilar

In this work, we obtained the numerical solution for the system of nonlinear time-fractional order advection-reaction-diffusion equation using the homotopy perturbation method using Laplace transform method with fractional order derivatives in Liouville-Caputo sense. The solution obtained is very useful and significant to analyze many physical phenomenons. The present technique demonstrates the coupling of homotopy perturbation method and the Laplace transform technique using He’s polynomials, which can be applied to numerous coupled systems of nonlinear fractional models to find the approximate numerical solutions. The salient features of the present work is the graphical presentations of the numerical solution of the concerned nonlinear coupled equation for several particular cases and showcasing the effect of reaction terms on the nature of solute concentration of the considered mathematical model for different particular cases. To validate the reliability, efficiency and accuracy of the proposed efficient scheme, a comparison of numerical solutions and exact solution are reported for Burgers’ coupled equations and other particular cases of concerned nonlinear coupled systems. Here we find high consistency and compatibility between exact and numerical solution to a high accuracy. Presentation of absolute errors for given examples are reported in tabulated and graphical forms that ensure the convergence rate of the numerical scheme.

Thomas Janvier Matongo, Jean Gaston Tamba, Léopold Mba et al.

Data presented on this paper are from the collection on the experimental site during a 12 months period, corresponding to the two seasons of the year. The site is located in the city of Douala in Cameroon, in a hot and humid zone. The experimental premises are located above the ground floor of a storey-building. They are built of 20 cm thick hollow breezeblocks with interior and exterior cement plastering, and they consist of the following: an open uninhabited room; a closed uninhabited room; and an inhabited room. The data acquisition system was achieved by the thermo-hygrometers and the anemometer placed in the rooms in accordance with the ASHRAE 55 standard [1], on instruments for measuring thermal comfort parameters in buildings. Collected data consists of the following: temperature, relative humidity and air velocity outside the site; the temperature and relative humidity inside the different rooms. These parameters are collected with a one-hour time step. The matlab software is used to calculate the maximum, minimum, average and standard deviation for each measured parameter. several areas are used for data processing: the search for causal links between the climatic parameters of the site, and those of the indoor environments of the buildings; data prediction on a one year's history basis; the impact of each experimental scenario on the thermal behaviour of the room; the assessment of the heat transfer in the room; the evaluation of the potential for energy savings in the room.

Hironori Washizaki

It is essential to discuss the role, difficulties, and opportunities concerning people of different gender in the field of software engineering research, education, and industry. Although some literature reviews address software engineering and gender, it is still unclear how research and practices in Asia exist for handling gender aspects in software development and engineering. We conducted a systematic literature review to grasp the comprehensive view of gender research and practices in Asia. We analyzed the 32 identified papers concerning countries and publication years among 463 publications. Researchers and practitioners from various organizations actively work on gender research and practices in some countries, including China, India, and Turkey. We identified topics and classified them into seven categories varying from personal mental health and team building to organization. Future research directions include investigating the synergy between (regional) gender aspects and cultural concerns and considering possible contributions and dependency among different topics to have a solid foundation for accelerating further research and getting actionable practices.

Margarita Chasapi, Pablo Antolin, Annalisa Buffa

This work introduces a reduced order modeling (ROM) framework for the solution of parameterized second-order linear elliptic partial differential equations formulated on unfitted geometries. The goal is to construct efficient projection-based ROMs, which rely on techniques such as the reduced basis method and discrete empirical interpolation. The presence of geometrical parameters in unfitted domain discretizations entails challenges for the application of standard ROMs. Therefore, in this work we propose a methodology based on i) extension of snapshots on the background mesh and ii) localization strategies to decrease the number of reduced basis functions. The method we obtain is computationally efficient and accurate, while it is agnostic with respect to the underlying discretization choice. We test the applicability of the proposed framework with numerical experiments on two model problems, namely the Poisson and linear elasticity problems. In particular, we study several benchmarks formulated on two-dimensional, trimmed domains discretized with splines and we observe a significant reduction of the online computational cost compared to standard ROMs for the same level of accuracy. Moreover, we show the applicability of our methodology to a three-dimensional geometry of a linear elastic problem.

Marcelo Raschi, Oriol Lloberas-Valls, Alfredo Huespe et al.

The authors have shown in previous contributions that reduced order modeling with optimal cubature applied to finite element square (FE2) techniques results in a reliable and affordable multiscale approach, the HPR-FE2 technique. Such technique is assessed here for an industrial case study of a generic 3D reinforced composite whose microstructure is represented by two general microcells accounting for different deformation mechanisms, microstrucural phases and geometry arrangement. Specifically, in this approach the microstrain modes used for building the reduced order model (ROM) are obtained through standard proper orthogonal decomposition (POD) techniques applied over snapshots of a representative sampling strain space. Additionally, a reduced number of integration points is obtained by exactly integrating the main free energy modes resulting from the sampling energy snapshots. The outcome consists of a number of dominant strain modes integrated over a remarkably reduced number of integration points which provide the support to evaluate the constitutive behavior of the microstructural phases. It is emphasized that stresses are computed according to the selected constitutive law at the reduced integration points and, therefore, the strategy inherits advantageous properties such as model completeness and customization of material properties. Overall results are discussed in terms of the consistency of the multiscale analysis, customization of the microscopic material parameters and speedup ratios compared to high-fidelity finite element (HF) simulations.

Mohammed A. Almomani, Mohamad I. Al-Widyan, Sulaiman M. Mohaidat

The high strength-to- weight ratio of titanium alloys allows their use in jet engines. However, their use is restricted by susceptibility to oxidation at high temperatures. In this study, the possibility of increasing the operating temperature of titanium alloys through using Yttrium Aluminum Oxide (YAG) as a thermal barrier coating material for Ti-6Al-4V substrate is studied. The study concludes that YAG can be utilized to increase the operating temperature of Ti-6Al-4V titanium alloy from around 350 °C to 800 °C due to its low thermal conductivity and phase stability up to its melting point. In addition, its lower oxygen diffusivity in comparison with the standard YSZ material will provide a better protection of the titanium substrate from oxidation. In this work, coating was created using atmospheric plasma spray. X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) were used to examine coatings' composition and structure. The coating was characterized by thermal shock test, Vickers hardness test and adhesion strength test. X-ray diffraction indicated that the coating was of a partially crystalline Y3Al5O12 composition. The coating was porous with excellent thermal shock resistance at 800 oC, with a Vickers micro-hardness of 331.35 HV and adhesion strength of 17.6 MPa.

Supriyanto Supriyanto, Ismanto Ismanto, Nuryo Suwito

Penelitian ini bertujuan untuk memanfaatkan energi yang terkandung di dalam ban bekas menjadi bahan bakar cair. Sebuah metode experimental nyata dengan temperatur pyrolisis sebagai variabel bebas dan viskositas, densitas, dan flash point sebagai variabel terikat. Sementara itu, suhu kondensor dan tekanan dijadikan sebagai variabel kontrol. Data menunjukkan adanya pengaruh temperatur terhadap hasil yang didapat, semakin tinggi temperatur, semakin banyak minyak yang diperoleh. Bahan baku juga sangat mempengaruhi jumlah dan kualitas bahan bakar cair yang dihasilkan. Terakhir, penggunaan katalis pada proses pyrolisis ban bekas mengurangi fraksi cairan namun meningkatkan kualitas produk.

Yeye Wen, Enlai Gao, Zhenxing Hu et al.

Negative Poisson’s ratio, offering unusual properties, is displayed by several materials and predicted for graphene. This work demonstrates such behaviors in monolithic films with interconnected networks of close-packed graphene laminates, and tunability through the chemistry and microstructures.