The accumulation mechanisms and spatial distribution of debonding damage in fiber-reinforced polymer composites under combined tension and shear loading are not well understood. To tackle this research gap, X-ray computed tomography has been utilized to observe the debonding damage between epoxy and CFPR rods in cruciform specimens. An in-situ loading rig was used to perform tension tests, with different combined stresses applied by varying the orientation of the embedded reinforcements. After loading, the damage volumes have been extracted and visualized in 3D to comprehensively examine the spatial distribution of debonding. The in-situ and ex-situ experimental results confirm that the distribution and propagation of interface cracks are largely dependent on the ratio of tension to shear and the position of adjacent reinforcements. Additionally, critical parameters such as debonding angles, crack opening displacements, and deflecting angles have been quantitatively analyzed. Based on the results, the authors proposed three representative models to describe the dimensional properties of interface cracks, and an empirical formula that reveals the positional correlation between interface cracks on adjacent reinforcements. Considering the universality of combined loading in engineering applications, a full understanding of the resulting debonding damage can significantly contribute to the optimization of composite design methodologies.
Materials of engineering and construction. Mechanics of materials
Monisha Yuvaraj, At Prabhakar, Varadhan Skm
et al.
In severely impaired stroke subjects without visible movements, implementing robot-assisted therapy based on movement intention decoded from electromyogram (EMG) requires both sufficient residual EMG to drive robotic assistance and a subject-specific detector to ensure accurate, low-latency detection. However, identifying such a detector is challenging, particularly when the presence of residual EMG in a given subject is unknown. This paper proposes a systematic approach to distinguish between EMG data when the subject is relaxed versus attempting a movement. We investigated six different detector types and separation measures using retrospective EMG data from a previous randomized controlled trial. The results indicate that the approximate generalized likelihood ratio (AGLR) detector, along with the modified Hodges and modified Lidierth detectors, achieved the best separation between the data when a subject is relaxed compared to when he/she attempts movements. Using a subset of clinician-annotated data to evaluate detection performance, the modified Hodges detector combined with probability difference-sum ratio measure (MH-PDSR) showed good performance in terms of both accuracy and latency. Based on the EMG data from 30 severe stroke, we propose a PDSR threshold of 0.7 with the modified Hodges detector to identify stroke subjects with sufficient residual EMG. These findings suggest that the MH-PDSR approach can be used to learn a maximally separating detector for a given subject which can be used both to screen stroke subjects for residual EMG and to provide a detector to drive robotic assistance if residual EMG is present. Further validation using larger datasets and evaluation of the resulting human machine interaction is warranted.
Abstract Different artificial intelligence (AI) methods have been applied to various aspects of rock mechanics, but the fact that none of these methods have been used as a standard implies that doubt as to their generality and validity still exists. For this, a literature review of application of AI to the field of rock mechanics is presented. Comprehensive studies of the researches published in the top journals relative to the fields of rock mechanics, computer applications in engineering, and the textbooks were conducted. The performances of the AI methods that have been used in rock mechanics applications were evaluated. The literature review shows that AI methods have successfully been used to solve various problems in the rock mechanics field and they performed better than the traditional empirical, mathematical or statistical methods. However, their practical applicability is still an issue of concern as many of the existing AI models require some level of expertise before they can be used, because they are not in the form of tractable mathematical equations. Thus some advanced AI methods are still yet to be explored. The limited availability of dataset for the AI simulations is also identified as a major problem. The solutions to the identified problems and the possible future research focus were proposed in the study subsequently.
Ionic conductive hydrogel has recently garnered significant research attention due to its potential applications in the field of wearable and flexible electronics. Nonetheless, the integration of multifunctional and synergistic advantages, including reliable electronic properties, high swelling capacity, exceptional mechanical characteristics, and self-adhesive properties, presents an ongoing challenge. In this study, we have developed an ionic conductive hydrogel through the co-polymerization of 4-Acryloylmorpholine (ACMO) and sodium acrylate using UV curing technology. The hydrogel exhibits excellent mechanical properties, high conductivity, superior swelling capacity, and remarkable self-adhesive attributes. The hydrogel serves as a highly sensitive strain sensor, enabling precise monitoring of both substantial and subtle human motions. Furthermore, the hydrogel demonstrates the capability to adhere to human skin, functioning as a human-machine interface for the detection of physiological signals, including electromyogram (EMG) signals, with low interfacial impedance. This work is anticipated to yield a new class of stretchable and conductive materials with diverse potential applications, ranging from flexible sensors and wearable bio-electronics to contributions in the field of artificial intelligence.
Milos Petrovic, Dimitrije Cabarkapa, Jelena Aleksic
et al.
Objective: The purpose of this study was to investigate differences in countermovement jump (CMJ) force–time metrics between male and female youth basketball players. Methods: Twenty-two female and seventeen male basketball players (ages 12–16) performed CMJs on a portable force plate system (VALD Performance). The data collected were analyzed for differences in force–time characteristics, specifically during the concentric and eccentric phases of the CMJ. Results: The results showed no statistically significant differences in anthropometric characteristics between the sexes. However, male athletes demonstrated better performance in several force–time metrics during the concentric phase of the CMJ, including concentric impulse, peak velocity, and mean power, ultimately leading to higher vertical jump heights. Sex-specific differences in the eccentric phase were less pronounced, though males exhibited greater relative eccentric mean power. Conclusions: The findings suggest that male players tend to display greater force and power-producing capabilities during the propulsive (concentric) phase of the CMJ. These differences highlight the importance of tailoring training programs to address specific needs, particularly focusing on enhancing concentric force and power production in female basketball players.
Mechanics of engineering. Applied mechanics, Descriptive and experimental mechanics
Dilara Börte Emiroglu, Aleksandar Bekčić, Dalia Dranseikiene
et al.
Granular hydrogels have been increasingly exploited in biomedical applications, including wound healing and cardiac repair. Despite their utility, design guidelines for engineering their macroscale properties remain limited, as we do not understand how the properties of granular hydrogels emerge from collective interactions of their microgel building blocks. In this work, we related building block features (stiffness and size) to the macroscale properties of granular hydrogels using contact mechanics. We investigated the mechanics of the microgel packings through dynamic oscillatory rheology. In addition, we modeled the system as a collection of two-body interactions and applied the Zwanzig and Mountain formula to calculate the plateau modulus and viscosity of the granular hydrogels. The calculations agreed with the dynamic mechanical measurements and described how microgel properties and contact deformations define the rheology of granular hydrogels. These results support a rational design framework for improved engineering of this fascinating class of materials.
The formulation used by the most of studies on elastic torus are either Reissner mixed formulation or Novozhilov's complex-form one, however, for vibration and some displacement boundary related problem of torus, those formulations face a great challenge. It is highly demanded to have a displacement-type formulation for torus. In this paper, we will carry on author's previous work [B.H. Sun, Closed-form solution of axisymmetric slender elastic toroidal shells. J. of Engineering Mechanics, 136 (2010) 1281-1288.], and with the help of our own maple code, we are able to simulate some typical problems of torus. The numerical results are verified by both finite element analysis and H. Reissner's formulation. Our investigations show that both deformation and stress response of an elastic torus are sensitive to the radius ratio, and suggest that the analysis of a torus should be done by using the bending theory of a shell, and also reveal that the inner torus is stronger than outer torus due to the property of their Gaussian curvature. One of the most interesting discovery is that the crowns of a torus are the turning point of the Gaussion curvature at ϕ = 0, π, where the mechanics response of inner and outer torus is almost separated.
P. Migdal, Klementyna Jankiewicz, Pawel Grabarz
et al.
Abstract. Virtual Lab by Quantum Flytrap is a no-code online laboratory of an optical table, presenting quantum phenomena interactively and intuitively. It supports a real-time simulation of up to three entangled photons. Users can place typical optical elements (such as beam splitters, polarizers, Faraday rotators, and detectors) with a drag-and-drop graphical interface. Virtual Lab operates in two modes. The sandbox mode allows users to compose arbitrary setups. Quantum Game serves as an introduction to Virtual Lab features, approachable for users with no prior exposure to quantum mechanics. We introduce visual representation of entangled states and entanglement measures. It includes interactive visualizations of the ket notation and a heatmap-like visualization of quantum operators. These quantum visualizations can be applied to any discrete quantum system, including quantum circuits with qubits and spin chains. These tools are available as open-source TypeScript packages – Quantum Tensors and BraKetVue. Virtual Lab makes it possible to explore the nature of quantum physics (state evolution, entanglement, and measurement), to simulate quantum computing (e.g., the Deutsch-Jozsa algorithm), to use quantum cryptography (e.g., the Ekert protocol), to explore counterintuitive quantum phenomena (e.g., quantum teleportation and the Bell inequality violation), and to recreate historical experiments (e.g., the Michelson–Morley interferometer).
This paper presents a mechanical model of the partitioned-pipe mixer (PPM) in case where pipe of the static mixer rotates with angular periodic velocity. Mixing becomes more efficient if the forcing of fluid mixing process is time periodic. Chaos in duct flows can be achieved by time modulation or by spatial changes along the duct axis. The values of Lyapunov exponents for flow in PPM are calculated.
Computer engineering. Computer hardware, Mechanics of engineering. Applied mechanics
Abstract Accurate and real-time short-term traffic flow prediction is the core technology of an intelligent transportation system. In this paper, the vehicle conservation principle of traffic flow mechanics is applied to study the differential equation of traffic flow is established by analysing traffic flow parameters. Using the principle of grey difference information, and a grey model of traffic flow in a road section is proposed. This model obtains traffic flow information about traffic flow inflow and congestion via matrix least squares technology and obtains the time response function and modelling steps of the model using a mathematical analysis method, which is applied to short-term traffic flow prediction. The results of three short-term traffic flow cases show that the simulation and prediction results of the new model are better than those of other grey models and two machine learning methods. Relevant information about the traffic flow parameters obtained by the new model is consistent with an actual situation of traffic flow.
Aborobaa Abdelfatah N., Ghamry Khaled A., Saleh Amr
et al.
High-speed on/off solenoid valves (HSVs) are digital vales commonly used in hydraulic power systems. These valves are usually used in pressure and flow control which requires high dynamic and energy performance to improve the control accuracy. This paper aims to propose a new control method used to improve the dynamic and energy performance of HSVs. The proposed method is based on the pulse width modulation (PWM) technique implemented by LabVIEW software and NI myRIO. Based on that, NI myRIO has a real-time module; no feedback is needed. A mathematical model of the HSV is introduced, describing each subsystem of the vale and its interactions with each other. The proposed method is validated under different operating conditions. The results show that applying the proposed control method on the HSV will reduce the valve spool closing time by 72% and reduce energy consumption by 94% compared to the traditional on/off control method.
Engineering (General). Civil engineering (General), Mechanics of engineering. Applied mechanics
Nguyen Thi Nhat Hang, Yong Yang, Nguyen Quang Thanh Nam
et al.
In our review, we have presented a summary of the research accomplishments of nanostructured multimetal-based electrocatalysts synthesized by modified polyol methods, especially the special case of Pt-based nanoparticles associated with increasing potential applications for batteries, capacitors, and fuel cells. To address the problems raised in serious environmental pollution, disease, health, and energy shortages, we discuss and present an improved polyol process used to synthesize nanoparticles from Pt metal to Pt-based bimetal, and Pt-based multimetal catalysts in the various forms of alloy and shell core nanostructures by practical experience, experimental skills, and the evidences from the designed polyol processes. In their prospects, there are the micro/nanostructured variants of hybrid Pt/nanomaterials, typically such as Pt/ABO<sub>3</sub>-type perovskite, Pt/AB<sub>2</sub>O<sub>4</sub>-type ferrite, Pt/CoFe<sub>2</sub>O<sub>4</sub>, Pt/oxide, or Pt/ceramic by modified polyol processes for the development of electrocatalysis and energy technology. In the future, we suggest that both the polyol and the sol-gel processes of diversity and originality, and with the use of various kinds of water, alcohols, polyols, other solvents, reducing agents, long-term capping and stabilizing agents, and structure- and property-controlling agents, are very effectively used in the controlled synthesis of micro/nanoparticles and micro/nanomaterials. It is understood that at the levels of controlling and modifying molecules, ions, atoms, and nano/microscales, the polyol or sol-gel processes, and their technologies are effectively combined in bottom-up and top-down approaches, as are the simplest synthetic methods of physics, chemistry, and biology from the most common aqueous solutions as well as possible experimental conditions.
In the present paper, we develop a novel method for structural health monitoring of multi-storey frame structures with the capability to detect and localise local damage. The method uses so-called spatial incompatibility filters, which are continuously distributed strain-type sensors only sensitive to incompatibilities. In the first part of the paper the concept of incompatibility filters is introduced for multi-storey frame structures and it is shown how these filters can be used to detect and localise local cracks in frame structures. In the second part of the paper we study the use of incompatibility filters put into practice by piezoelectric sensor networks for structural health monitoring of a three-storey frame structure. The design of the piezoelectric sensor network is based on an analytical analysis of the frame structure within the framework of the method developed in the first part of the paper and a numerical verification using three-dimensional Finite Elements completes the paper
ABSTRACT: Curvature is one of the most important features of lipid membranes in living cells, which significantly influences the structure of lipid membranes and their interaction with proteins. Taken the human islet amyloid polypeptide (hIAPP), an important protein related to the pathogenesis of type II diabetes, as an example, we performed molecular dynamics (MD) simulations to study the interaction between the protein and the lipid structures with varied curvatures. We found that the lipids in the high curvature membrane pack loosely with high mobility. The hIAPP initially forms H-bonds with the membrane surface that anchored the protein, and then inserts into the membrane through the hydrophobic interactions between the residues and the hydrophobic tails of the lipids. hIAPP can insert into the membrane more deeply with a larger curvature and with a stronger binding strength. Our result provided important insights into the mechanism of the membrane curvature-dependent property of proteins with molecular details.
In this work we have discussed the impact of thermal radiation on heat transfer to nanofluid flow over an unsteady permeable stretching sheet using various types of arbitrary shape nanoparticles of Copper (Cu), Silver (Ag), Alumina (Al 2 O 3 ), and Titania Oxide (TiO 2 ) in the base fluid. Suitable transformations have been employed to build ODEs from the partial differential equations. Numerical results are therefore obtained particularly for cylindrical shape and spherical shape nanoparticles. Our analysis substantiates that the velocity and temperature profiles increases with enhanced thermal radiation parameter. Further, Nusselt number is more advanced for the nanofluid that contains cylindrical shape nanoparticles as compared to spherical shape nanoparticles.
Artikel ini menyajikan studi kasus untuk mengetahui efektivitas problem based learning untuk peningkatan kompetensi sistem starter siswa Sekolah Menengah Kejuruan. Jenis penelitian adalah quasi experimental. Subyek penelitian adalah siswa Sekolah Menengah Kejuruan di Yogyakarta. Penelitian menggunakan desain non-equivalent control group. Teknik pengumpulan data menggunakan observasi dan tes. Teknik analisis data menggunakan nonparametrik uji mann-whitney dan wilconox. Hasil penelitian menunjukan bahwa problem based learning efektif untuk peningkatan kompetensi sistem starter siswa Sekolah Menengah Kejuruan.
Mechanical engineering and machinery, Mechanics of engineering. Applied mechanics